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Therien, Michael J.

Overview:

Our research involves the synthesis of compounds, supramolecular assemblies, nano-scale objects, and electronic materials with unusual ground-and excited-state characteristics, and interrogating these structures using state-of-the-art transient optical, spectroscopic, photophysical, and electrochemical methods. Over chemical dimensions that span molecules to materials, we probe experimental and theoretical aspects of charge migration reactions and ultrafast electron transfer processes. Insights into the structure-property relationships of molecular, nanoscale, and macroscopic materials allow us to fabricate polarizable and hyperpolarizable chromophores, structures for molecular electronics applications, optical limiters, and a wide range of other electrooptic and photonic materials that include novel conducting polymers, structures for solar energy conversion, and new platforms for in vivo optical imaging. Other efforts in our laboratory involve the elaborating de novo electron- and energy-transfer proteins, interrogating catalytic redox reactions, designing catalysts for small molecule activation, and developing new tools to manipulate nanoscale structures.

Positions:

William R. Kenan, Jr. Professor of Chemistry in Trinity College of Arts and Sciences

Chemistry
Trinity College of Arts & Sciences

Professor of Chemistry

Chemistry
Trinity College of Arts & Sciences

Professor of Biomedical Engineering

Biomedical Engineering
Pratt School of Engineering

Faculty Network Member of The Energy Initiative

Duke University Energy Initiative
Institutes and Provost's Academic Units

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1982

B.S. — University of St. Andrews (Scotland)

Ph.D. 1987

Ph.D. — University of California at San Diego

Nih Postdoctoral Research Fellow, Chemistry

California Institute of Technology

News:

Grants:

Training in Medical Imaging

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 15, 2003
End Date
August 31, 2019

NSF/DMR-BSF: Collaborative Research: Spin Selective Electron Transmission through Highly Conjugated Multi[(porphinato)metal] Oligomers

Administered By
Chemistry
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
August 15, 2016
End Date
July 31, 2019

GAANN - Department of Chemistry

Administered By
Chemistry
AwardedBy
Department of Education
Role
Mentor
Start Date
September 01, 2015
End Date
August 31, 2018

Organic, Nanoscale, and Self-Assembled Structures Relevant to Solar Energy Conversion

Administered By
Chemistry
AwardedBy
Department of Energy
Role
Principal Investigator
Start Date
September 01, 2009
End Date
February 28, 2018

Nuclear Data Measurements Using Gamma Rays and Radiation Detector Development

Administered By
Physics
AwardedBy
US Department of Homeland Security
Role
Co-Principal Investigator
Start Date
September 15, 2011
End Date
August 31, 2017

Collaborative Research: De novo Protein Constructs for Photosynthetic Energy Transduction

Administered By
Chemistry
AwardedBy
National Science Foundation
Role
Principal Investigator
Start Date
August 15, 2014
End Date
July 31, 2017

Circumventing Therapeutic Resistance and the Emergence of Disseminated Breast Cancer Cells

Administered By
Chemistry
AwardedBy
United States Army Medical Research Acquisition Activity
Role
Principal Investigator
Start Date
July 01, 2013
End Date
June 30, 2017

University Training Program in Biomolecular and Tissue Engineering

Administered By
Biomedical Engineering
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
July 01, 1994
End Date
June 30, 2017

Charge-Transfer Dynamics Relevant to Protein-Mediated Energy Transduction

Administered By
Chemistry
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 2006
End Date
July 31, 2016

NSEC on Molecular Function at the Nano/Bio Interface

Administered By
Chemistry
AwardedBy
University of Pennsylvania
Role
Principal Investigator
Start Date
September 01, 2008
End Date
August 31, 2014

Purchase of a Q-TOF LC/MS System

Administered By
Chemistry
AwardedBy
National Institutes of Health
Role
Major User
Start Date
August 09, 2010
End Date
August 08, 2011

Novel Compositions of Matter for Capacitor Applications

Administered By
Chemistry
AwardedBy
Office of Naval Research
Role
Principal Investigator
Start Date
August 15, 2008
End Date
September 30, 2010

NIR- Emissive Polymersomal Markers for Molecular-Level Detection of Metastasis

Administered By
Chemistry
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
September 01, 2006
End Date
July 31, 2010
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Awards:

Fellow. Flemish Academy of Arts and Sciences .

Type
National
Awarded By
Flemish Academy of Arts and Sciences
Date
January 01, 2009

International Francqui Chair. Belgium .

Type
International
Awarded By
Belgium
Date
January 01, 2008

Fellow. American Association for the Advancement of Science .

Type
National
Awarded By
American Association for the Advancement of Science
Date
January 01, 2005

American Chemical Society Philadelphia Section Award . American Chemical Society .

Type
National
Awarded By
American Chemical Society
Date
January 01, 2004

Porphyrins and Phthalocyanines Young Investigator Award . Society of Porphyrins & Phthalocyanines .

Type
National
Awarded By
Society of Porphyrins & Phthalocyanines
Date
January 01, 2002

Camille Dreyfus Teacher-Scholar . Camille and Henry Dreyfus Foundation, Inc..

Type
National
Awarded By
Camille and Henry Dreyfus Foundation, Inc.
Date
January 01, 1997

E. I. duPont de Nemours Young Faculty Award . DuPont.

Type
National
Awarded By
DuPont
Date
January 01, 1995

Sloan Research Fellowship-Chemistry. Alfred P. Sloan Foundation.

Type
National
Awarded By
Alfred P. Sloan Foundation
Date
January 01, 1995

National Science Foundation Young Investigator . National Science Foundation .

Type
National
Awarded By
National Science Foundation
Date
January 01, 1993

Beckman Young Investigators (BYI). Arnold and Mabel Beckman Foundation.

Type
National
Awarded By
Arnold and Mabel Beckman Foundation
Date
January 01, 1992

Scholars. Searle Scholars.

Type
National
Awarded By
Searle Scholars
Date
January 01, 1991

Publications:

Synthesis and characterization of Na(Gd0.5Lu0.5)F4: Nd3+,a core-shell free multifunctional contrast agent

© 2016 Elsevier B.V.Compared to conventional core-shell structures, core-shell free nanoparticles with multiple functionalities offer several advantages such as minimal synthetic complexity and low production cost. In this paper, we present the synthesis and characterization of Nd3+ doped Na(Gd0.5Lu0.5)F4 as a core-shell free nanoparticle system with three functionalities. Nanocrystals with 20 nm diameter, high crystallinity and a narrow particle size distributions were synthesized by the solvothermal method and characterized by various analytical techniques to understand their phase and morphology. Fluorescence characteristics under near infrared (NIR) excitation at 808 nm as well as X-ray excitation were studied to explore their potential in NIR optical and X-ray imaging. At 1.0 mol% Nd concentration, we observed a quantum yield of 25% at 1064 nm emission with 13 W/cm2 excitation power density which is sufficiently enough for imaging applications. Under 130 kVp (5 mA) power of X-ray excitation, Nd3+ doped Na(Gd0.5Lu0.5)F4 shows the characteristic emission bands of Gd3+ and Nd3+ with the strongest emission peak at 1064 nm due to Nd3+. Furthermore, magnetization measurements show that the nanocrystals are paramagnetic in nature with a calculated magnetic moment per particle of ∼570 μB at 2T. These preliminary results support the suitability of the present nanophosphor as a multimodal contrast agent with three imaging features viz. optical, magnetic and X-ray.

Authors
Mimun, LC; Ajithkumar, G; Rightsell, C; Langloss, BW; Therien, MJ; Sardar, DK
MLA Citation
Mimun, LC, Ajithkumar, G, Rightsell, C, Langloss, BW, Therien, MJ, and Sardar, DK. "Synthesis and characterization of Na(Gd0.5Lu0.5)F4: Nd3+,a core-shell free multifunctional contrast agent." Journal of Alloys and Compounds 695 (February 25, 2017): 280-285.
Source
scopus
Published In
Journal of Alloys and Compounds
Volume
695
Publish Date
2017
Start Page
280
End Page
285
DOI
10.1016/j.jallcom.2016.10.202

Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor-Acceptor-Donor Nonlinear Optical Chromophores.

Octopolar D2-symmetric chromophores, based on the MPZnM supermolecular motif in which (porphinato)zinc(II) (PZn) and ruthenium(II) polypyridyl (M) structural units are connected via ethyne linkages, were synthesized. These structures take advantage of electron-rich meso-arylporphyrin or electron-poor meso-(perfluoroalkyl)porphyrin macrocycles, unsubstituted terpyridyl and 4'-pyrrolidinyl-2,2';6',2″-terpyridyl ligands, and modulation of metal(II) polypyridyl-to-(porphinato)zinc connectivity, to probe how electronic and geometric factors impact the measured hyperpolarizability. Transient absorption spectra obtained at early time delays (tdelay < 400 fs) demonstrate fast excited-state relaxation, and formation of a highly polarized T1 excited state; the T1 states of these chromophores display expansive, intense T1 → T n absorption manifolds that dominate the 800-1200 nm region of the NIR, long (μs) triplet-state lifetimes, and unusually large NIR excited absorptive extinction coefficients [ε(T1 → T n ) ∼ 105 M-1 cm-1]. Dynamic hyperpolarizability (βλ) values were determined from hyper-Rayleigh light scattering (HRS) measurements, carried out at multiple incident irradiation wavelengths spanning the 800-1500 nm spectral domain. The measured βHRS value (4600 ± 1200 × 10-30 esu) for one of these complexes, RuPZnRu, is the largest yet reported for any chromophore at a 1500 nm irradiation wavelength, highlighting that appropriate engineering of strong electronic coupling between multiple charge-transfer oscillators provides a critical design strategy to realize octopolar NLO chromophores exhibiting large βHRS values at telecom-relevant wavelengths. Generalized Thomas-Kuhn sum (TKS) rules were utilized to compute the effective excited-state-to-excited-state transition dipole moments from experimental linear-absorption spectra; these data were then utilized to compute hyperpolarizabilities as a function of frequency, that include two- and three-state contributions for both β zzz and β xzx tensor components to the RuPZnRu hyperpolarizability spectrum. This analysis predicts that the β zzz and β xzx tensor contributions to the RuPZnRu hyperpolarizability spectrum maximize near 1550 nm, in agreement with experimental data. The TKS analysis suggests that relative to analogous dipolar chromophores, octopolar supermolecules will be likely characterized by more intricate dependences of the measured hyperpolarizability upon irradiation wavelength due to the interactions among multiple different β tensor components.

Authors
Nayak, A; Park, J; De Mey, K; Hu, X; Duncan, TV; Beratan, DN; Clays, K; Therien, MJ
MLA Citation
Nayak, A, Park, J, De Mey, K, Hu, X, Duncan, TV, Beratan, DN, Clays, K, and Therien, MJ. "Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor-Acceptor-Donor Nonlinear Optical Chromophores." ACS central science 2.12 (December 16, 2016): 954-966.
Website
http://hdl.handle.net/10161/13733
PMID
28058285
Source
epmc
Published In
ACS Central Science
Volume
2
Issue
12
Publish Date
2016
Start Page
954
End Page
966
DOI
10.1021/acscentsci.6b00291

Mean First-Passage Times in Biology

Authors
Polizzi, NF; Therien, MJ; Beratan, DN
MLA Citation
Polizzi, NF, Therien, MJ, and Beratan, DN. "Mean First-Passage Times in Biology." Israel Journal of Chemistry 56.9-10 (October 2016): 816-824.
Source
crossref
Published In
Israel Journal of Chemistry
Volume
56
Issue
9-10
Publish Date
2016
Start Page
816
End Page
824
DOI
10.1002/ijch.201600040

First-order hyperpolarizabilities of chiral, polymer-wrapped single-walled carbon nanotubes.

We report the first-order hyperpolarizabilities (βHRS values) of individualized, length-sorted (700 ± 50 nm long) (6,5) SWNTs and corresponding polymer-wrapped (6,5) SWNT superstructures. These SWNT-based nanohybrids feature semiconducting polymers that wrap the SWNT surface in an exclusive left-handed helical fashion. Manipulation of the polymer electronic structures in these well-defined nanoscale objects provides a new avenue to modulate the magnitude of βHRS at long wavelength (1280 nm).

Authors
Depotter, G; Olivier, J-H; Glesner, MG; Deria, P; Bai, Y; Bullard, G; Kumbhar, AS; Therien, MJ; Clays, K
MLA Citation
Depotter, G, Olivier, J-H, Glesner, MG, Deria, P, Bai, Y, Bullard, G, Kumbhar, AS, Therien, MJ, and Clays, K. "First-order hyperpolarizabilities of chiral, polymer-wrapped single-walled carbon nanotubes." Chemical communications (Cambridge, England) 52.82 (October 2016): 12206-12209.
PMID
27722425
Source
epmc
Published In
Chemical Communications
Volume
52
Issue
82
Publish Date
2016
Start Page
12206
End Page
12209
DOI
10.1039/c6cc06190g

Real Time Dosimetry for Gynecologic Brachytherapy: Initial Results of a Prospective Clinical Trial (vol 93, pg S203, 2015)

Authors
Chino, JP; Belley, MD; Chang, Z; Langloss, B; Yoshizumi, TT; Therien, MJ; Craciunescu, OI
MLA Citation
Chino, JP, Belley, MD, Chang, Z, Langloss, B, Yoshizumi, TT, Therien, MJ, and Craciunescu, OI. "Real Time Dosimetry for Gynecologic Brachytherapy: Initial Results of a Prospective Clinical Trial (vol 93, pg S203, 2015)." INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 95.2 (June 1, 2016): 858-859.
Source
wos-lite
Published In
International Journal of Radiation Oncology, Biology, Physics
Volume
95
Issue
2
Publish Date
2016
Start Page
858
End Page
859

WE-DE-201-07: Measurement of Real-Time Dose for Tandem and Ovoid Brachytherapy Procedures Using a High Precision Optical Fiber Radiation Detector.

Development of a novel on-line dosimetry tool is needed to move toward patient-specific quality assurance measurements for Ir-192 HDR brachytherapy to verify accurate dose delivery to the intended location. This work describes the development and use of a nano-crystalline yttrium oxide inorganic scintillator based optical-fiber detector capable of acquiring real-time high-precision dose measurements during tandem and ovoid (T&O) gynecological (GYN) applicator Ir-192 HDR brachytherapy procedures.An optical-fiber detector was calibrated by acquiring light output measurements in liquid water at 3, 5, 7, and 9cm radial source-detector-distances from an Ir-192 HDR source. A regression model was fit to the data to describe the relative light output per unit dose (TG-43 derived) as a function of source-detector-distance. Next, the optical-fiber detector was attached to a vaginal balloon fixed to a Varian Fletcher-Suit-Delclos-style applicator (to mimic clinical setup), and localized by acquiring high-resolution computed tomography (CT) images. To compare the physical point dose to the TPS calculated values (TG-43 and Acuros-BV), a phantom measurement was performed, by submerging the T&O applicator in a liquid water bath and delivering a treatment template representative of a clinical T&O procedure. The fiber detector collected scintillation signal as a function of time, and the calibration data was applied to calculate both real-time dose rate, and cumulative dose.Fiber cumulative dose values were 100.0cGy, 94.3cGy, and 348.9cGy from the tandem, left ovoid, and right ovoid dwells, respectively (total of 443.2cGy). A plot of real time dose rate during the treatment was also acquired. The TPS values at the fiber location were 458.4cGy using TG-43, and 437.6cGy using Acuros-BV calculated as Dm,m (per TG-186).The fiber measured dose value agreement was 3% vs TG-43 and -1% vs Acuros-BV. This fiber detector opens up new possibilities for performing patient-specific quality assurance for Ir-192 HDR GYN procedures. Funding from Coulter Foundation, Duke Bio-medical Engineering. Company is being created around the detector technology. Duke holds patents on the technology.

Authors
Belley, MD; Faught, A; Moore, B; Subashi, E; Langloss, B; Therien, MJ; Yoshizumi, TT; Chino, JP; Craciunescu, O
MLA Citation
Belley, MD, Faught, A, Moore, B, Subashi, E, Langloss, B, Therien, MJ, Yoshizumi, TT, Chino, JP, and Craciunescu, O. "WE-DE-201-07: Measurement of Real-Time Dose for Tandem and Ovoid Brachytherapy Procedures Using a High Precision Optical Fiber Radiation Detector." Medical physics 43.6 (June 2016): 3809-3810.
PMID
28048361
Source
epmc
Published In
Medical physics
Volume
43
Issue
6
Publish Date
2016
Start Page
3809
End Page
3810
DOI
10.1118/1.4957812

Photoinduced Electron Transfer Elicits a Change in the Static Dielectric Constant of a de Novo Designed Protein.

We provide a direct measure of the change in effective dielectric constant (ε(S)) within a protein matrix after a photoinduced electron transfer (ET) reaction. A linked donor-bridge-acceptor molecule, PZn-Ph-NDI, consisting of a (porphinato)Zn donor (PZn), a phenyl bridge (Ph), and a naphthalene diimide acceptor (NDI), is shown to be a "meter" to indicate protein dielectric environment. We calibrated PZn-Ph-NDI ET dynamics as a function of solvent dielectric, and computationally de novo designed a protein SCPZnI3 to bind PZn-Ph-NDI in its interior. Mapping the protein ET dynamics onto the calibrated ET catalogue shows that SCPZnI3 undergoes a switch in the effective dielectric constant following photoinduced ET, from ε(S) ≈ 8 to ε(S) ≈ 3.

Authors
Polizzi, NF; Eibling, MJ; Perez-Aguilar, JM; Rawson, J; Lanci, CJ; Fry, HC; Beratan, DN; Saven, JG; Therien, MJ
MLA Citation
Polizzi, NF, Eibling, MJ, Perez-Aguilar, JM, Rawson, J, Lanci, CJ, Fry, HC, Beratan, DN, Saven, JG, and Therien, MJ. "Photoinduced Electron Transfer Elicits a Change in the Static Dielectric Constant of a de Novo Designed Protein." Journal of the American Chemical Society 138.7 (February 3, 2016): 2130-2133.
PMID
26840013
Source
epmc
Published In
Journal of the American Chemical Society
Volume
138
Issue
7
Publish Date
2016
Start Page
2130
End Page
2133
DOI
10.1021/jacs.5b13180

Valence Band Dependent Charge Transport in Bulk Molecular Electronic Devices Incorporating Highly Conjugated Multi-[(Porphinato)Metal] Oligomers.

Molecular electronics offers the potential to control device functions through the fundamental electronic properties of individual molecules, but realization of such possibilities is typically frustrated when such specialized molecules are integrated into a larger area device. Here we utilize highly conjugated (porphinato)metal-based oligomers (PM(n) structures) as molecular wire components of nanotransfer printed (nTP) molecular junctions; electrical characterization of these "bulk" nTP devices highlights device resistances that depend on PM(n) wire length. Device resistance measurements, determined as a function of PM(n) molecular length, were utilized to evaluate the magnitude of a phenomenological β corresponding to the resistance decay parameter across the barrier; these data show that the magnitude of this β value is modulated via porphyrin macrocycle central metal atom substitution [β(PZn(n); 0.065 Å(-1)) < β(PCu(n); 0.132 Å(-1)) < β(PNi(n); 0.176 Å(-1))]. Cyclic voltammetric data, and ultraviolet photoelectron spectroscopic studies carried out at gold surfaces, demonstrate that these nTP device resistances track with the valence band energy levels of the PM(n) wire, which were modulated via porphyrin macrocycle central metal atom substitution. This study demonstrates the ability to fabricate "bulk" and scalable electronic devices in which function derives from the electronic properties of discrete single molecules, and underscores how a critical device function--wire resistance--may be straightforwardly engineered by PM(n) molecular composition.

Authors
Bruce, RC; Wang, R; Rawson, J; Therien, MJ; You, W
MLA Citation
Bruce, RC, Wang, R, Rawson, J, Therien, MJ, and You, W. "Valence Band Dependent Charge Transport in Bulk Molecular Electronic Devices Incorporating Highly Conjugated Multi-[(Porphinato)Metal] Oligomers." Journal of the American Chemical Society 138.7 (February 2016): 2078-2081.
PMID
26829704
Source
epmc
Published In
Journal of the American Chemical Society
Volume
138
Issue
7
Publish Date
2016
Start Page
2078
End Page
2081
DOI
10.1021/jacs.5b10772

Extreme electron polaron spatial delocalization in π-conjugated materials.

The electron polaron, a spin-1/2 excitation, is the fundamental negative charge carrier in π-conjugated organic materials. Large polaron spatial dimensions result from weak electron-lattice coupling and thus identify materials with unusually low barriers for the charge transfer reactions that are central to electronic device applications. Here we demonstrate electron polarons in π-conjugated multiporphyrin arrays that feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. Because the electron polaron dimension can be linked to key performance metrics in organic photovoltaics, light-emitting diodes, and a host of other devices, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties.

Authors
Rawson, J; Angiolillo, PJ; Therien, MJ
MLA Citation
Rawson, J, Angiolillo, PJ, and Therien, MJ. "Extreme electron polaron spatial delocalization in π-conjugated materials." Proceedings of the National Academy of Sciences of the United States of America 112.45 (November 2015): 13779-13783.
PMID
26512097
Source
epmc
Published In
Proceedings of the National Academy of Sciences of USA
Volume
112
Issue
45
Publish Date
2015
Start Page
13779
End Page
13783
DOI
10.1073/pnas.1512318112

Defusing redox bombs?

Authors
Polizzi, NF; Migliore, A; Therien, MJ; Beratan, DN
MLA Citation
Polizzi, NF, Migliore, A, Therien, MJ, and Beratan, DN. "Defusing redox bombs?." Proceedings of the National Academy of Sciences of the United States of America 112.35 (September 2015): 10821-10822.
PMID
26290579
Source
epmc
Published In
Proceedings of the National Academy of Sciences of USA
Volume
112
Issue
35
Publish Date
2015
Start Page
10821
End Page
10822
DOI
10.1073/pnas.1513520112

Unambiguous Diagnosis of Photoinduced Charge Carrier Signatures in a Stoichiometrically Controlled Semiconducting Polymer-Wrapped Carbon Nanotube Assembly.

Single-walled carbon nanotube (SWNT)-based nanohybrid compositions based on (6,5) chirality-enriched SWNTs ([(6,5) SWNTs]) and a chiral n-type polymer (S-PBN(b)-Ph4 PDI) that exploits a perylenediimide (PDI)-containing repeat unit are reported; S-PBN(b)-Ph4 PDI-[(6,5) SWNT] superstructures feature a PDI electron acceptor unit positioned at 3 nm intervals along the nanotube surface, thus controlling rigorously SWNT-electron acceptor stoichiometry and organization. Potentiometric studies and redox-titration experiments determine driving forces for photoinduced charge separation (CS) and thermal charge recombination (CR) reactions, as well as spectroscopic signatures of SWNT hole polaron and PDI radical anion (PDI(-.) ) states. Time-resolved pump-probe spectroscopic studies demonstrate that S-PBN(b)-Ph4 PDI-[(6,5) SWNT] electronic excitation generates PDI(-.) via a photoinduced CS reaction (τCS ≈0.4 ps, ΦCS ≈0.97). These experiments highlight the concomitant rise and decay of transient absorption spectroscopic signatures characteristic of the SWNT hole polaron and PDI(-.) states. Multiwavelength global analysis of these data provide two charge-recombination time constants (τCR ≈31.8 and 250 ps) that likely reflect CR dynamics involving both an intimately associated SWNT hole polaron and PDI(-.) charge-separated state, and a related charge-separated state involving PDI(-.) and a hole polaron site produced via hole migration along the SWNT backbone that occurs over this timescale.

Authors
Olivier, J-H; Park, J; Deria, P; Rawson, J; Bai, Y; Kumbhar, AS; Therien, MJ
MLA Citation
Olivier, J-H, Park, J, Deria, P, Rawson, J, Bai, Y, Kumbhar, AS, and Therien, MJ. "Unambiguous Diagnosis of Photoinduced Charge Carrier Signatures in a Stoichiometrically Controlled Semiconducting Polymer-Wrapped Carbon Nanotube Assembly." Angewandte Chemie (International ed. in English) 54.28 (July 2015): 8133-8138.
PMID
26014277
Source
epmc
Published In
Angewandte Chemie International Edition
Volume
54
Issue
28
Publish Date
2015
Start Page
8133
End Page
8138
DOI
10.1002/anie.201501364

Near-Infrared-to-Visible Photon Upconversion Enabled by Conjugated Porphyrinic Sensitizers under Low-Power Noncoherent Illumination

Authors
Olivier, J-H; Bai, Y; Uh, H; Yoo, H; Therien, MJ; Castellano, FN
MLA Citation
Olivier, J-H, Bai, Y, Uh, H, Yoo, H, Therien, MJ, and Castellano, FN. "Near-Infrared-to-Visible Photon Upconversion Enabled by Conjugated Porphyrinic Sensitizers under Low-Power Noncoherent Illumination." JOURNAL OF PHYSICAL CHEMISTRY A 119.22 (June 4, 2015): 5642-5649.
Source
wos-lite
Published In
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume
119
Issue
22
Publish Date
2015
Start Page
5642
End Page
5649
DOI
10.1021/acs.jpca.5b03199

Electron Spin Relaxation of Hole and Electron Polarons in π-Conjugated Porphyrin Arrays: Spintronic Implications.

Electron spin resonance (ESR) spectroscopic line shape analysis and continuous-wave (CW) progressive microwave power saturation experiments are used to probe the relaxation behavior and the relaxation times of charged excitations (hole and electron polarons) in meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZnn compounds), which can serve as models for the relevant states generated upon spin injection. The observed ESR line shapes for the PZnn hole polaron ([PZnn](+•)) and electron polaron ([PZnn](-•)) states evolve from Gaussian to more Lorentzian as the oligomer length increases from 1.9 to 7.5 nm, with solution-phase [PZnn](+•) and [PZnn](-•) spin-spin (T2) and spin-lattice (T1) relaxation times at 298 K ranging, respectively, from 40 to 230 ns and 0.2 to 2.3 μs. Notably, these very long relaxation times are preserved in thick films of these species. Because the magnitudes of spin-spin and spin-lattice relaxation times are vital metrics for spin dephasing in quantum computing or for spin-polarized transport in magnetoresistive structures, these results, coupled with the established wire-like transport behavior across metal-dithiol-PZnn-metal junctions, present meso-to-meso ethyne-bridged multiporphyrin systems as leading candidates for ambient-temperature organic spintronic applications.

Authors
Rawson, J; Angiolillo, PJ; Frail, PR; Goodenough, I; Therien, MJ
MLA Citation
Rawson, J, Angiolillo, PJ, Frail, PR, Goodenough, I, and Therien, MJ. "Electron Spin Relaxation of Hole and Electron Polarons in π-Conjugated Porphyrin Arrays: Spintronic Implications." The journal of physical chemistry. B 119.24 (June 2015): 7681-7689.
PMID
25697578
Source
epmc
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
119
Issue
24
Publish Date
2015
Start Page
7681
End Page
7689
DOI
10.1021/jp5122728

Near-Infrared-to-Visible Photon Upconversion Enabled by Conjugated Porphyrinic Sensitizers under Low-Power Noncoherent Illumination.

We report four supermolecular chromophores based on (porphinato)zinc(II) (PZn) and (polypyridyl)metal units bridged via ethyne connectivity (Pyr1RuPZn2, Pyr1RuPZnRuPyr1, Pyr1RuPZn2RuPyr1, and OsPZn2Os) that fulfill critical sensitizer requirements for NIR-to-vis triplet-triplet annihilation upconversion (TTA-UC) photochemistry. These NIR sensitizers feature: (i) broad, high oscillator strength NIR absorptivity (700 nm < λ(max(NIR)) < 770 nm; 6 × 10(4) M(-1) cm(-1) < extinction coefficient (λ(max(NIR))) < 1.6 × 10(5) M(-1) cm(-1); 820 cm(-1) < fwhm < 1700 cm(-1)); (ii) substantial intersystem crossing quantum yields; (iii) long, microsecond time scale T1 state lifetimes; and (iv) triplet states that are energetically poised for exergonic energy transfer to the molecular annihilator (rubrene). Using low-power noncoherent illumination at power densities (1-10 mW cm(-2)) similar to that of terrestrial solar photon illumination conditions, we demonstrate that Pyr1RuPZn2, Pyr1RuPZn2RuPyr1, and Pyr1RuPZnRuPyr1 sensitizers can be used in combination with the rubrene acceptor/annihilator to achieve TTA-UC: these studies represent the first examples whereby a low-power noncoherent NIR light source drives NIR-to-visible upconverted fluorescence centered in a spectral window within the bandgap of amorphous silicon.

Authors
Olivier, J-H; Bai, Y; Uh, H; Yoo, H; Therien, MJ; Castellano, FN
MLA Citation
Olivier, J-H, Bai, Y, Uh, H, Yoo, H, Therien, MJ, and Castellano, FN. "Near-Infrared-to-Visible Photon Upconversion Enabled by Conjugated Porphyrinic Sensitizers under Low-Power Noncoherent Illumination." June 2015.
PMID
25961428
Source
epmc
Published In
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume
119
Issue
22
Publish Date
2015
Start Page
5642
End Page
5649
DOI
10.1021/acs.jpca.5b03199

Single-Step Assembly of Multimodal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging.

Magnetic resonance imaging (MRI)- and near-infrared (NIR)-active, multimodal composite nanocarriers (CNCs) are prepared using a simple one-step process, flash nanoprecipitation (FNP). The FNP process allows for the independent control of the hydrodynamic diameter, co-core excipient and NIR dye loading, and iron oxide-based nanocrystal (IONC) content of the CNCs. In the controlled precipitation process, 10 nm IONCs are encapsulated into poly(ethylene glycol) (PEG) stabilized CNCs to make biocompatible T2 contrast agents. By adjusting the formulation, CNC size is tuned between 80 and 360 nm. Holding the CNC size constant at an intensity weighted average diameter of 99 ± 3 nm (PDI width 28 nm), the particle relaxivity varies linearly with encapsulated IONC content ranging from 66 to 533 × 10(-3) m(-1) s(-1) for CNCs formulated with 4-16 wt% IONC. To demonstrate the use of CNCs as in vivo MRI contrast agents, CNCs are surface functionalized with liver-targeting hydroxyl groups. The CNCs enable the detection of 0.8 mm(3) non-small cell lung cancer metastases in mice livers via MRI. Incorporating the hydrophobic, NIR dye tris-(porphyrinato)zinc(II) into CNCs enables complementary visualization with long-wavelength fluorescence at 800 nm. In vivo imaging demonstrates the ability of CNCs to act both as MRI and fluorescent imaging agents.

Authors
Pinkerton, NM; Gindy, ME; Calero-DdelC, VL; Wolfson, T; Pagels, RF; Adler, D; Gao, D; Li, S; Wang, R; Zevon, M; Yao, N; Pacheco, C; Therien, MJ; Rinaldi, C; Sinko, PJ; Prud'homme, RK
MLA Citation
Pinkerton, NM, Gindy, ME, Calero-DdelC, VL, Wolfson, T, Pagels, RF, Adler, D, Gao, D, Li, S, Wang, R, Zevon, M, Yao, N, Pacheco, C, Therien, MJ, Rinaldi, C, Sinko, PJ, and Prud'homme, RK. "Single-Step Assembly of Multimodal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging." Advanced healthcare materials 4.9 (June 2015): 1376-1385.
PMID
25925128
Source
epmc
Published In
Advanced healthcare materials
Volume
4
Issue
9
Publish Date
2015
Start Page
1376
End Page
1385
DOI
10.1002/adhm.201400766

Fiber-optic detector for real time dosimetry of a micro-planar x-ray beam.

Here, the authors describe a dosimetry measurement technique for microbeam radiation therapy using a nanoparticle-terminated fiber-optic dosimeter (nano-FOD).The nano-FOD was placed in the center of a 2 cm diameter mouse phantom to measure the deep tissue dose and lateral beam profile of a planar x-ray microbeam.The continuous dose rate at the x-ray microbeam peak measured with the nano-FOD was 1.91 ± 0.06 cGy s(-1), a value 2.7% higher than that determined via radiochromic film measurements (1.86 ± 0.15 cGy s(-1)). The nano-FOD-determined lateral beam full-width half max value of 420 μm exceeded that measured using radiochromic film (320 μm). Due to the 8° angle of the collimated microbeam and resulting volumetric effects within the scintillator, the profile measurements reported here are estimated to achieve a resolution of ∼0.1 mm; however, for a beam angle of 0°, the theoretical resolution would approach the thickness of the scintillator (∼0.01 mm).This work provides proof-of-concept data and demonstrates that the novel nano-FOD device can be used to perform real-time dosimetry in microbeam radiation therapy to measure the continuous dose rate at the x-ray microbeam peak as well as the lateral beam shape.

Authors
Belley, MD; Stanton, IN; Hadsell, M; Ger, R; Langloss, BW; Lu, J; Zhou, O; Chang, SX; Therien, MJ; Yoshizumi, TT
MLA Citation
Belley, MD, Stanton, IN, Hadsell, M, Ger, R, Langloss, BW, Lu, J, Zhou, O, Chang, SX, Therien, MJ, and Yoshizumi, TT. "Fiber-optic detector for real time dosimetry of a micro-planar x-ray beam." Medical physics 42.4 (April 2015): 1966-1972.
PMID
25832087
Source
epmc
Published In
Medical physics
Volume
42
Issue
4
Publish Date
2015
Start Page
1966
End Page
1972
DOI
10.1118/1.4915078

Caging metal ions with visible light-responsive nanopolymersomes.

Polymersomes are bilayer vesicles that self-assemble from amphiphilic diblock copolymers, and provide an attractive system for the delivery of biological and nonbiological molecules due to their environmental compatibility, mechanical stability, synthetic tunability, large aqueous core, and hyperthick hydrophobic membrane. Herein, we report a nanoscale photoresponsive polymersome system featuring a meso-to-meso ethyne-bridged bis[(porphinato)zinc] (PZn2) fluorophore hydrophobic membrane solute and dextran in the aqueous core. Upon 488 nm irradiation in solution or in microinjected zebrafish embryos, the polymersomes underwent deformation, as monitored by a characteristic red-shifted PZn2 emission spectrum and confirmed by cryo-TEM. The versatility of this system was demonstrated through the encapsulation and photorelease of a fluorophore (FITC), as well as two different metal ions, Zn(2+) and Ca(2+).

Authors
Griepenburg, JC; Sood, N; Vargo, KB; Williams, D; Rawson, J; Therien, MJ; Hammer, DA; Dmochowski, IJ
MLA Citation
Griepenburg, JC, Sood, N, Vargo, KB, Williams, D, Rawson, J, Therien, MJ, Hammer, DA, and Dmochowski, IJ. "Caging metal ions with visible light-responsive nanopolymersomes." Langmuir : the ACS journal of surfaces and colloids 31.2 (January 7, 2015): 799-807.
PMID
25518002
Source
epmc
Published In
Langmuir
Volume
31
Issue
2
Publish Date
2015
Start Page
799
End Page
807
DOI
10.1021/la5036689

Design of diethynyl porphyrin derivatives with high near infrared fluorescence quantum yields

Authors
Susumu, K; Therien, MJ
MLA Citation
Susumu, K, and Therien, MJ. "Design of diethynyl porphyrin derivatives with high near infrared fluorescence quantum yields." Journal of Porphyrins and Phthalocyanines 19.01-03 (January 2015): 205-218.
Source
crossref
Published In
Journal of Porphyrins and Phthalocyanines (Wiley)
Volume
19
Issue
01-03
Publish Date
2015
Start Page
205
End Page
218
DOI
10.1142/S1088424614501107

Unambiguous Diagnosis of Photoinduced Charge Carrier Signatures in a Stoichiometrically Controlled Semiconducting Polymer-Wrapped Carbon Nanotube Assembly

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Single-walled carbon nanotube (SWNT)-based nanohybrid compositions based on (6,5) chirality-enriched SWNTs ([(6,5) SWNTs]) and a chiral n-type polymer (S-PBN(b)-Ph<inf>4</inf>PDI) that exploits a perylenediimide (PDI)-containing repeat unit are reported; S-PBN(b)-Ph<inf>4</inf>PDI-[(6,5) SWNT] superstructures feature a PDI electron acceptor unit positioned at 3 nm intervals along the nanotube surface, thus controlling rigorously SWNT-electron acceptor stoichiometry and organization. Potentiometric studies and redox-titration experiments determine driving forces for photoinduced charge separation (CS) and thermal charge recombination (CR) reactions, as well as spectroscopic signatures of SWNT hole polaron and PDI radical anion (PDI<sup>-.</sup>) states. Time-resolved pump-probe spectroscopic studies demonstrate that S-PBN(b)-Ph<inf>4</inf>PDI-[(6,5) SWNT] electronic excitation generates PDI<sup>-.</sup> via a photoinduced CS reaction (τ<inf>CS</inf>≈0.4 ps, Φ<inf>CS</inf>≈0.97). These experiments highlight the concomitant rise and decay of transient absorption spectroscopic signatures characteristic of the SWNT hole polaron and PDI<sup>-.</sup> states. Multiwavelength global analysis of these data provide two charge-recombination time constants (τ<inf>CR</inf>≈31.8 and 250 ps) that likely reflect CR dynamics involving both an intimately associated SWNT hole polaron and PDI<sup>-.</sup> charge-separated state, and a related charge-separated state involving PDI<sup>-.</sup> and a hole polaron site produced via hole migration along the SWNT backbone that occurs over this timescale.

Authors
Olivier, J-H; Park, J; Deria, P; Rawson, J; Bai, Y; Kumbhar, AS; Therien, MJ
MLA Citation
Olivier, J-H, Park, J, Deria, P, Rawson, J, Bai, Y, Kumbhar, AS, and Therien, MJ. "Unambiguous Diagnosis of Photoinduced Charge Carrier Signatures in a Stoichiometrically Controlled Semiconducting Polymer-Wrapped Carbon Nanotube Assembly." Angewandte Chemie - International Edition 54.28 (2015): 8133-8138.
Source
scival
Published In
Angewandte Chemie International Edition
Volume
54
Issue
28
Publish Date
2015
Start Page
8133
End Page
8138
DOI
10.1002/anie.201501364

Electronic and optical properties of Er-doped Y 2 O 2 S phosphors

Authors
Pokhrel, M; Kumar, GA; Ma, C-G; Brik, MG; Langloss, BW; Stanton, IN; Therien, MJ; Sardar, DK; Mao, Y
MLA Citation
Pokhrel, M, Kumar, GA, Ma, C-G, Brik, MG, Langloss, BW, Stanton, IN, Therien, MJ, Sardar, DK, and Mao, Y. "Electronic and optical properties of Er-doped Y 2 O 2 S phosphors." J. Mater. Chem. C 3.43 (2015): 11486-11496.
Source
crossref
Published In
Journal of Materials Chemistry C
Volume
3
Issue
43
Publish Date
2015
Start Page
11486
End Page
11496
DOI
10.1039/C5TC02665B

Tailoring Porphyrin-Based Electron Accepting Materials for Organic Photovoltaics

Authors
Rawson, J; Stuart, AC; You, W; Therien, MJ
MLA Citation
Rawson, J, Stuart, AC, You, W, and Therien, MJ. "Tailoring Porphyrin-Based Electron Accepting Materials for Organic Photovoltaics." JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 136.50 (December 17, 2014): 17561-17569.
Source
wos-lite
Published In
Journal of the American Chemical Society
Volume
136
Issue
50
Publish Date
2014
Start Page
17561
End Page
17569
DOI
10.1021/ja5097418

Potentiometric, electronic, and transient absorptive spectroscopic properties of oxidized single-walled carbon nanotubes helically wrapped by ionic, semiconducting polymers in aqueous and organic media.

We report the first direct cyclic voltammetric determination of the valence and conduction band energy levels for noncovalently modified (6,5) chirality enriched SWNTs [(6,5) SWNTs] in which an aryleneethynylene polymer monolayer helically wraps the nanotube surface at periodic and constant morphology. Potentiometric properties as well as the steady-state and transient absorption spectroscopic signatures of oxidized (6,5) SWNTs were probed as a function of the electronic structure of the aryleneethynylene polymer that helically wraps the nanotube surface, the solvent dielectric, and nanotube hole polaron concentration. These data: (i) highlight the utility of these polymer-SWNT superstructures in experiments that establish the potentiometric valence and conduction band energy levels of semiconducting carbon nanotubes; (ii) provide a direct measure of the (6,5) SWNT hole polaron delocalization length (2.75 nm); (iii) determine steady-state and transient electronic absorptive spectroscopic signatures that are uniquely associated with the (6,5) SWNT hole polaron state; and (iv) demonstrate that modulation of semiconducting polymer frontier orbital energy levels can drive spectral shifts of SWNT hole polaron transitions as well as regulate SWNT valence and conduction band energies.

Authors
Deria, P; Olivier, J-H; Park, J; Therien, MJ
MLA Citation
Deria, P, Olivier, J-H, Park, J, and Therien, MJ. "Potentiometric, electronic, and transient absorptive spectroscopic properties of oxidized single-walled carbon nanotubes helically wrapped by ionic, semiconducting polymers in aqueous and organic media." Journal of the American Chemical Society 136.40 (October 2014): 14193-14199.
PMID
25211354
Source
epmc
Published In
Journal of the American Chemical Society
Volume
136
Issue
40
Publish Date
2014
Start Page
14193
End Page
14199
DOI
10.1021/ja507457z

Hapticity-dependent charge transport through carbodithioate-terminated [5,15-bis(phenylethynyl)porphinato]zinc(II) complexes in metal-molecule-metal junctions.

Single molecule break junction experiments and nonequilibrium Green's function calculations using density functional theory (NEGF-DFT) of carbodithioate- and thiol-terminated [5,15-bis(phenylethynyl)-10,20-diarylporphinato]zinc(II) complexes reveal the impact of the electrode-linker coordination mode on charge transport at the single-molecule level. Replacement of thiolate (-S(-)) by the carbodithioate (-CS2(-)) anchoring motif leads to an order of magnitude increase of single molecule conductance. In contrast to thiolate-terminated structures, metal-molecule-metal junctions that exploit the carbodithioate linker manifest three distinct conductance values. We hypothesize that the magnitudes of these conductances depend upon carbodithoate linker hapticity with measured conductances across Au-[5,15-bis(4'-(dithiocarboxylate)phenylethynyl)-10,20-diarylporphinato]zinc(II)-Au junctions the greatest when both anchoring groups attach to the metal surface in a bidentate fashion. We support this hypothesis with NEGF-DFT calculations, which consider the electron transport properties for specific binding geometries. These results provide new insights into the origin of molecule-to-molecule conductance heterogeneity in molecular charge transport measurements and the factors that optimize electrode-molecule-electrode electronic coupling and maximize the conductance for charge transport.

Authors
Li, Z; Smeu, M; Park, T-H; Rawson, J; Xing, Y; Therien, MJ; Ratner, MA; Borguet, E
MLA Citation
Li, Z, Smeu, M, Park, T-H, Rawson, J, Xing, Y, Therien, MJ, Ratner, MA, and Borguet, E. "Hapticity-dependent charge transport through carbodithioate-terminated [5,15-bis(phenylethynyl)porphinato]zinc(II) complexes in metal-molecule-metal junctions." Nano letters 14.10 (October 2014): 5493-5499.
PMID
25255444
Source
epmc
Published In
Nano Letters
Volume
14
Issue
10
Publish Date
2014
Start Page
5493
End Page
5499
DOI
10.1021/nl502466a

Femtosecond pulse train shaping improves two-photon excited fluorescence measurements.

Measurements of two-photon absorption (TPA) cross sections are greatly confounded by even very weak linear absorption, for example from hot bands. In this case, the experimental power dependence of fluorescence from amplified and mode-locked laser systems can differ drastically, even if the peak intensity is adjusted to be the same in both cases. A simple pulse train shaping method suppresses linear contributions and extracts the nonlinear absorption cross section, demonstrated here for a meso-to-meso ethyne-bridged bis[(porphinato)zinc(II)] fluorophore (DD) at 800 nm. This approach permits reliable TPA cross-section measurement, even with standard modelocked lasers under conditions identical to that used for multiphoton microscopy.

Authors
Park, JK; Fischer, MC; Susumu, K; Therien, MJ; Warren, WS
MLA Citation
Park, JK, Fischer, MC, Susumu, K, Therien, MJ, and Warren, WS. "Femtosecond pulse train shaping improves two-photon excited fluorescence measurements." Optics letters 39.19 (October 2014): 5606-5609.
PMID
25360939
Source
epmc
Published In
Optics Letters
Volume
39
Issue
19
Publish Date
2014
Start Page
5606
End Page
5609
DOI
10.1364/ol.39.005606

Europium- and lithium-doped yttrium oxide nanocrystals that provide a linear emissive response with X-ray radiation exposure.

Eu- and Li-doped yttrium oxide nanocrystals [Y2-xO3; Eux, Liy], in which Eu and Li dopant ion concentrations were systematically varied, were developed and characterized (TEM, XRD, Raman spectroscopic, UV-excited lifetime, and ICP-AES data) in order to define the most emissive compositions under specific X-ray excitation conditions. These optimized [Y2-xO3; Eux, Liy] compositions display scintillation responses that: (i) correlate linearly with incident radiation exposure at X-ray energies spanning from 40-220 kVp, and (ii) manifest no evidence of scintillation intensity saturation at the highest evaluated radiation exposures [up to 4 Roentgen per second]. For the most emissive nanoscale scintillator composition, [Y1.9O3; Eu0.1, Li0.16], excitation energies of 40, 120, and 220 kVp were chosen to probe the dependence of the integrated emission intensity upon X-ray exposure-rate in energy regimes having different mass-attenuation coefficients and where either the photoelectric or the Compton effect governs the scintillation mechanism. These experiments demonstrate for the first time for that for comparable radiation exposures, when the scintillation mechanism is governed by the photoelectric effect and a comparably larger mass-attenuation coefficient (120 kVp excitation), greater integrated emission intensities are recorded relative to excitation energies where the Compton effect regulates scintillation (220 kVp) in nanoscale [Y2-xO3; Eux] crystals. Nanoscale [Y1.9O3; Eu0.1, Li0.16] (70 ± 20 nm) was further exploited as a detector material in a prototype fiber-optic radiation sensor. The scintillation intensity from the [Y1.9O3; Eu0.1, Li0.16]-modified, 400 μm sized optical fiber tip, recorded using a CCD-photodetector and integrated over the 605-617 nm wavelength domain, was correlated with radiation exposure using a Precision XRAD 225Cx small-animal image guided radiation therapy (IGRT) system. For both 80 and 225 kVp energies, this radiotransparent device recorded scintillation intensities that tracked linearly with total radiation exposure, highlighting its capability to provide alternately accurate dosimetry measurements for both diagnostic imaging (80 kVp) and radiation therapy treatment (225 kVp).

Authors
Stanton, IN; Belley, MD; Nguyen, G; Rodrigues, A; Li, Y; Kirsch, DG; Yoshizumi, TT; Therien, MJ
MLA Citation
Stanton, IN, Belley, MD, Nguyen, G, Rodrigues, A, Li, Y, Kirsch, DG, Yoshizumi, TT, and Therien, MJ. "Europium- and lithium-doped yttrium oxide nanocrystals that provide a linear emissive response with X-ray radiation exposure." Nanoscale 6.10 (May 2014): 5284-5288.
PMID
24696056
Source
epmc
Published In
Nanoscale
Volume
6
Issue
10
Publish Date
2014
Start Page
5284
End Page
5288
DOI
10.1039/c4nr00497c

Biochemistry and theory of proton-coupled electron transfer.

Authors
Migliore, A; Polizzi, NF; Therien, MJ; Beratan, DN
MLA Citation
Migliore, A, Polizzi, NF, Therien, MJ, and Beratan, DN. "Biochemistry and theory of proton-coupled electron transfer." Chemical reviews 114.7 (April 2014): 3381-3465. (Review)
PMID
24684625
Source
epmc
Published In
Chemical Reviews
Volume
114
Issue
7
Publish Date
2014
Start Page
3381
End Page
3465
DOI
10.1021/cr4006654

Single-walled carbon nanotubes wrapped by helically chiral, ionic, semiconducting polymers: New nanoscale compositions for energy capture, conversion and storage

Authors
Olivier, J-H; Park, J; Deria, P; Kumbhar, AS; Andrian-Albescu, M; Therien, MJ
MLA Citation
Olivier, J-H, Park, J, Deria, P, Kumbhar, AS, Andrian-Albescu, M, and Therien, MJ. "Single-walled carbon nanotubes wrapped by helically chiral, ionic, semiconducting polymers: New nanoscale compositions for energy capture, conversion and storage." March 16, 2014.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
247
Publish Date
2014

Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers: New opportunities for the design of electro-optically functional nanoscopic materials

Authors
Deria, P; Olivier, J-H; Christopher, VBD; Park, J; Kumbhar, AS; Andrian-Albescu, M; Saven, JG; Therien, MJ
MLA Citation
Deria, P, Olivier, J-H, Christopher, VBD, Park, J, Kumbhar, AS, Andrian-Albescu, M, Saven, JG, and Therien, MJ. "Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers: New opportunities for the design of electro-optically functional nanoscopic materials." March 16, 2014.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
247
Publish Date
2014

One-Pot Solvothermal Synthesis of Highly Emissive, Sodium-Codoped, LaF3 and BaLaF5 Core-Shell Upconverting Nanocrystals

Authors
Stecher, J; Rohlfing, A; Therien, M
MLA Citation
Stecher, J, Rohlfing, A, and Therien, M. "One-Pot Solvothermal Synthesis of Highly Emissive, Sodium-Codoped, LaF3 and BaLaF5 Core-Shell Upconverting Nanocrystals." Nanomaterials 4.1 (March 2014): 69-86.
Source
crossref
Published In
Nanomaterials
Volume
4
Issue
1
Publish Date
2014
Start Page
69
End Page
86
DOI
10.3390/nano4010069

Fluence-dependent singlet exciton dynamics in length-sorted chirality-enriched single-walled carbon nanotubes.

We utilize individualized, length-sorted (6,5)-chirality enriched single-walled carbon nanotubes (SWNTs) having dimensions of 200 and 800 nm, femtosecond transient absorption spectroscopy, and variable excitation fluences that modulate the exciton density per nanotube unit length, to interrogate nanotube exciton/biexciton dynamics. For pump fluences below 30 μJ/cm(2), transient absorption (TA) spectra of (6,5) SWNTs reveal the instantaneous emergence of the exciton to biexciton transition (E11 → E11,BX) at 1100 nm; in contrast, under excitation fluences exceeding 100 μJ/cm(2), this TA signal manifests a rise time (τ rise ∼ 250 fs), indicating that E11 state repopulation is required to produce this signal. Femtosecond transient absorption spectroscopic data acquired over the 900-1400 nm spectral region of the near-infrared (NIR) region for (6,5) SWNTs, as a function of nanotube length and exciton density, reveal that over time delays that exceed 200 fs exciton-exciton interactions do not occur over spatial domains larger than 200 nm. Furthermore, the excitation fluence dependence of the E11 → E11,BX transient absorption signal demonstrates that relaxation of the E11 biexciton state (E11,BX) gives rise to a substantial E11 state population, as increasing delay times result in a concomitant increase of E11 → E11,BX transition oscillator strength. Numerical simulations based on a three-state model are consistent with a mechanism whereby biexcitons are generated at high excitation fluences via sequential SWNT ground- and E11-state excitation that occurs within the 980 nm excitation pulse duration. These studies that investigate fluence-dependent TA spectral evolution show that SWNT ground → E11 and E11 → E11,BX excitations are coresonant and provide evidence that E11,BX → E11 relaxation constitutes a significant decay channel for the SWNT biexciton state over delay times that exceed 200 fs, a finding that runs counter to assumptions made in previous analyses of SWNT biexciton dynamical data where exciton-exciton annihilation has been assumed to play a dominant role.

Authors
Park, J; Deria, P; Olivier, J-H; Therien, MJ
MLA Citation
Park, J, Deria, P, Olivier, J-H, and Therien, MJ. "Fluence-dependent singlet exciton dynamics in length-sorted chirality-enriched single-walled carbon nanotubes." Nano Lett 14.2 (February 12, 2014): 504-511.
PMID
24329134
Source
pubmed
Published In
Nano Letters
Volume
14
Issue
2
Publish Date
2014
Start Page
504
End Page
511
DOI
10.1021/nl403511s

Femtosecond pulse train shaping for accurate two-photon excited fluorescence measurements

We report a simple measurement method that exploits pulse train shaping to suppress linear contributions to the fluorescence, and allows for extraction of the two-photon absorption cross sections. © 2014 OSA.

Authors
Park, JK; Fischer, MC; Susumu, K; Therien, MJ; Warren, WS
MLA Citation
Park, JK, Fischer, MC, Susumu, K, Therien, MJ, and Warren, WS. "Femtosecond pulse train shaping for accurate two-photon excited fluorescence measurements." January 1, 2014.
Source
scopus
Published In
Laser Science, LS 2014
Publish Date
2014

Ionic self-assembly provides dense arrays of individualized, aligned single-walled carbon nanotubes.

Wrap and stack: Polyanionic [arylene]ethynylene polymers that helically wrap single-walled carbon nanotubes (SWNTs) enable the production of functionalized SWNTs that are soluble in organic solvents. These SWNTs can assemble into structures featuring aligned nanotubes that maintain the optoelectronic properties of individual SWNTs.

Authors
Olivier, J-H; Deria, P; Park, J; Kumbhar, A; Andrian-Albescu, M; Therien, MJ
MLA Citation
Olivier, J-H, Deria, P, Park, J, Kumbhar, A, Andrian-Albescu, M, and Therien, MJ. "Ionic self-assembly provides dense arrays of individualized, aligned single-walled carbon nanotubes." Angew Chem Int Ed Engl 52.49 (December 2, 2013): 13080-13085.
PMID
24130000
Source
pubmed
Published In
Angewandte Chemie International Edition
Volume
52
Issue
49
Publish Date
2013
Start Page
13080
End Page
13085
DOI
10.1002/anie.201307256

Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles.

Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant release based on the intended in vivo application.

Authors
Qi, W; Ghoroghchian, PP; Li, G; Hammer, DA; Therien, MJ
MLA Citation
Qi, W, Ghoroghchian, PP, Li, G, Hammer, DA, and Therien, MJ. "Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles." Nanoscale 5.22 (November 21, 2013): 10908-10915.
PMID
24056924
Source
pubmed
Published In
Nanoscale
Volume
5
Issue
22
Publish Date
2013
Start Page
10908
End Page
10915
DOI
10.1039/c3nr03250g

Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers.

We establish the requisite design for aryleneethynylene polymers that give rise to single-handed helical wrapping of single-walled carbon nanotubes (SWNTs). Highly charged semiconducting polymers that utilize either an (R)- or (S)-1,1'-bi-2-naphthol component in their respective conjugated backbones manifest HRTEM and AFM images of single-chain-wrapped SWNTs that reveal significant preferences for the anticipated helical wrapping handedness; statistical analysis of these images, however, indicates that ∼20% of the helical structures are formed with the "unexpected" handedness. CD spectroscopic data, coupled with TDDFT-based computational studies that correlate the spectral signatures of semiconducting polymer-wrapped SWNT assemblies with the structural properties of the chiral 1,1'-binaphthyl unit, suggest strongly that two distinct binaphthalene SWNT binding modes, cisoid-facial and cisoid-side, are possible for these polymers, with the latter mode responsible for inversion of helical chirality and the population of polymer-SWNT superstructures that feature the unexpected polymer helical wrapping chirality at the nanotube surface. Analogous aryleneethynylene polymers were synthesized that feature a 2,2'-(1,3-benzyloxy)-bridged (b)-1,1'-bi-2-naphthol unit: this 1,1'-bi-2-naphthol derivative is characterized by a bridging 2,2'-1,3 benzyloxy tether that restricts the torsional angle between the two naphthalene subunits along its C1-C1' chirality axis to larger, oblique angles that facilitate more extensive van der Waals contact of the naphthyl subunits with the nanotube. Similar microscopic, spectroscopic, and computational studies determine that chiral polymers based on conformationally restricted transoid binaphthyl units direct preferential facial binding of the polymer with the SWNT and thereby guarantee helically wrapped polymer-nanotube superstructures of fixed helical chirality. Molecular dynamics simulations provide an integrated picture tying together the global helical superstructure and conformational properties of the binaphthyl units: a robust, persistent helical handedness is preferred for the conformationally restricted transoid binaphthalene polymer. Further examples of similar semiconducting polymer-SWNT superstructures are reported that demonstrate that the combination of single-handed helical wrapping and electronic structural modification of the conjugated polymer motif opens up new opportunities for engineering the electro-optic functionality of nanoscale objects.

Authors
Deria, P; Von Bargen, CD; Olivier, J-H; Kumbhar, AS; Saven, JG; Therien, MJ
MLA Citation
Deria, P, Von Bargen, CD, Olivier, J-H, Kumbhar, AS, Saven, JG, and Therien, MJ. "Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers." J Am Chem Soc 135.43 (October 30, 2013): 16220-16234.
PMID
24070370
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
135
Issue
43
Publish Date
2013
Start Page
16220
End Page
16234
DOI
10.1021/ja408430v

The evolution of spin distribution in the photoexcited triplet state of ethyne-elaborated porphyrins.

Ethyne elaboration of a (porphinato)Zn(II) (PZn) chromophoric core renders fine control over the zero-field splitting (ZFS) parameters of the lowest energy photoexcited triplet state (T1), resulting in the ability to manipulate the spin distribution and establish highly symmetrical coincident optical and magnetic principal axes.

Authors
Angiolillo, PJ; Rawson, J; Frail, PR; Therien, MJ
MLA Citation
Angiolillo, PJ, Rawson, J, Frail, PR, and Therien, MJ. "The evolution of spin distribution in the photoexcited triplet state of ethyne-elaborated porphyrins." Chem Commun (Camb) 49.84 (October 28, 2013): 9722-9724.
PMID
23982224
Source
pubmed
Published In
Chemical Communications
Volume
49
Issue
84
Publish Date
2013
Start Page
9722
End Page
9724
DOI
10.1039/c3cc44903c

Origins of the helical wrapping of phenyleneethynylene polymers about single-walled carbon nanotubes.

The highly charged, conjugated polymer poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) has been shown to wrap single-wall carbon nanotubes (SWNTs), adopting a robust helical superstructure. Surprisingly, PPES adopts a helical rather than a linear conformation when adhered to SWNTs. The complexes formed by PPES and related polymers upon helical wrapping of a SWNT are investigated using atomistic molecular dynamics (MD) simulations in the presence and absence of aqueous solvent. In simulations of the PPES/SWNT system in an aqueous environment, PPES spontaneously takes on a helical conformation. A potential of mean force, ΔA(ξ), is calculated as a function of ξ, the component of the end-to-end vector of the polymer chain projected on the SWNT axis; ξ is a monotonic function of the polymer's helical pitch. ΔA(ξ) provides a means to quantify the relative free energies of helical conformations of the polymer when wrapped about the SWNT. The aqueous system possesses a global minimum in ΔA(ξ) at the experimentally observed value of the helical pitch. The presence of this minimum is associated with preferred side chain conformations, where the side chains adopt conformations that provide van der Waals contact between the tubes and the aliphatic components of the side chains, while exposing the anionic sulfonates for aqueous solvation. The simulations provide a free energy estimate of a 0.2 kcal/mol/monomer preference for the helical over the linear conformation of the PPES/SWNT system in an aqueous environment.

Authors
Von Bargen, CD; MacDermaid, CM; Lee, O-S; Deria, P; Therien, MJ; Saven, JG
MLA Citation
Von Bargen, CD, MacDermaid, CM, Lee, O-S, Deria, P, Therien, MJ, and Saven, JG. "Origins of the helical wrapping of phenyleneethynylene polymers about single-walled carbon nanotubes." J Phys Chem B 117.42 (October 24, 2013): 12953-12965.
PMID
23941695
Source
pubmed
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
117
Issue
42
Publish Date
2013
Start Page
12953
End Page
12965
DOI
10.1021/jp402140t

Computational de novo design and characterization of a protein that selectively binds a highly hyperpolarizable abiological chromophore.

This work reports the first example of a single-chain protein computationally designed to contain four α-helical segments and fold to form a four-helix bundle encapsulating a supramolecular abiological chromophore that possesses exceptional nonlinear optical properties. The 109-residue protein, designated SCRPZ-1, binds and disperses an insoluble hyperpolarizable chromophore, ruthenium(II) [5-(4'-ethynyl-(2,2';6',2″-terpyridinyl))-10,20-bis(phenyl)porphinato]zinc(II)-(2,2';6',2″-terpyridine)(2+) (RuPZn) in aqueous buffer solution at a 1:1 stoichiometry. A 1:1 binding stoichiometry of the holoprotein is supported by electronic absorption and circular dichroism spectra, as well as equilibrium analytical ultracentrifugation and size exclusion chromatography. SCRPZ-1 readily dimerizes at micromolar concentrations, and an empirical redesign of the protein exterior produced a stable monomeric protein, SCRPZ-2, that also displayed a 1:1 protein:cofactor stoichiometry. For both proteins in aqueous buffer, the encapsulated cofactor displays photophysical properties resembling those exhibited by the dilute RuPZn cofactor in organic solvent: femtosecond, nanosecond, and microsecond time scale pump-probe transient absorption spectroscopic data evince intensely absorbing holoprotein excited states having large spectral bandwidth that penetrate deep in the near-infrared energy regime; the holoprotein electronically excited triplet state exhibits a microsecond time scale lifetime characteristic of the RuPZn chromophore. Hyper-Rayleigh light scattering measurements carried out at an incident irradiation wavelength of 1340 nm for these holoproteins demonstrate an exceptional dynamic hyperpolarizabilty (β1340 = 3100 × 10(-30) esu). X-ray reflectivity measurements establish that this de novo-designed hyperpolarizable protein can be covalently attached with high surface density to a silicon surface without loss of the cofactor, indicating that these assemblies provide a new approach to bioinspired materials that have unique electro-optic functionality.

Authors
Fry, HC; Lehmann, A; Sinks, LE; Asselberghs, I; Tronin, A; Krishnan, V; Blasie, JK; Clays, K; DeGrado, WF; Saven, JG; Therien, MJ
MLA Citation
Fry, HC, Lehmann, A, Sinks, LE, Asselberghs, I, Tronin, A, Krishnan, V, Blasie, JK, Clays, K, DeGrado, WF, Saven, JG, and Therien, MJ. "Computational de novo design and characterization of a protein that selectively binds a highly hyperpolarizable abiological chromophore." J Am Chem Soc 135.37 (September 18, 2013): 13914-13926.
PMID
23931685
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
135
Issue
37
Publish Date
2013
Start Page
13914
End Page
13926
DOI
10.1021/ja4067404

Enhancement of dominant UV emission in 10 nm gallium-codoped, upconverting nanocrystals

Authors
Stecher, JT; Stanton, IN; Therien, MJ
MLA Citation
Stecher, JT, Stanton, IN, and Therien, MJ. "Enhancement of dominant UV emission in 10 nm gallium-codoped, upconverting nanocrystals." September 8, 2013.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
246
Publish Date
2013

Exploiting plasmon-induced hot electrons in molecular electronic devices.

Plasmonic nanostructures can induce a number of interesting responses in devices. Here we show that hot electrons can be extracted from plasmonic particles and directed into a molecular electronic device, which represents a new mechanism of transfer from light to electronic transport. To isolate this phenomenon from alternative and sometimes simultaneous mechanisms of plasmon-exciton interactions, we designed a family of hybrid nanostructure devices consisting of Au nanoparticles and optoelectronically functional porphyin molecules that enable precise control of electronic and optical properties. Temperature- and wavelength-dependent transport measurements are analyzed in the context of optical absorption spectra of the molecules, the Au particle arrays, and the devices. Enhanced photocurrent associated with exciton generation in the molecule is distinguished from enhancements due to plasmon interactions. Mechanisms of plasmon-induced current are examined, and it is found that hot electron generation can be distinguished from other possibilities.

Authors
Conklin, D; Nanayakkara, S; Park, T-H; Lagadec, MF; Stecher, JT; Chen, X; Therien, MJ; Bonnell, DA
MLA Citation
Conklin, D, Nanayakkara, S, Park, T-H, Lagadec, MF, Stecher, JT, Chen, X, Therien, MJ, and Bonnell, DA. "Exploiting plasmon-induced hot electrons in molecular electronic devices." ACS Nano 7.5 (May 28, 2013): 4479-4486.
PMID
23550717
Source
pubmed
Published In
ACS Nano
Volume
7
Issue
5
Publish Date
2013
Start Page
4479
End Page
4486
DOI
10.1021/nn401071d

Coupled-oscillator photophysics and the elaboration of chromophores having exceptional nonlinear optical properties

Authors
Therien, MJ
MLA Citation
Therien, MJ. "Coupled-oscillator photophysics and the elaboration of chromophores having exceptional nonlinear optical properties." April 7, 2013.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
245
Publish Date
2013

Biodegradable Polymersomes for the Delivery of Gemcitabine to Panc-1 Cells.

Traditional anticancer chemotherapy often displays toxic side effects, poor bioavailability, and a low therapeutic index. Targeting and controlled release of a chemotherapeutic agent can increase drug bioavailability, mitigate undesirable side effects, and increase the therapeutic index. Here we report a polymersome-based system to deliver gemcitabine to Panc-1 cells in vitro. The polymersomes were self-assembled from a biocompatible and completely biodegradable polymer, poly(ethylene oxide)-poly(caprolactone), PEO-PCL. We showed that we can encapsulate gemcitabine within stable 200 nm vesicles with a 10% loading efficiency. These vesicles displayed a controlled release of gemcitabine with 60% release after 2 days at physiological pH. Upon treatment of Panc-1 cells in vitro, vesicles were internalized as verified with fluorescently labeled polymersomes. Clonogenic assays to determine cell survival were performed by treating Panc-1 cells with varying concentrations of unencapsulated gemcitabine (FreeGem) and polymersome-encapsulated gemcitabine (PolyGem) for 48 hours. 1 μM PolyGem was equivalent in tumor cell toxicity to 1 μM FreeGem, with a one log cell kill observed. These studies suggest that further investigation on polymersome-based drug formulations is warranted for chemotherapy of pancreatic cancer.

Authors
Sood, N; Jenkins, WT; Yang, X-Y; Shah, NN; Katz, JS; Koch, CJ; Frail, PR; Therien, MJ; Hammer, DA; Evans, SM
MLA Citation
Sood, N, Jenkins, WT, Yang, X-Y, Shah, NN, Katz, JS, Koch, CJ, Frail, PR, Therien, MJ, Hammer, DA, and Evans, SM. "Biodegradable Polymersomes for the Delivery of Gemcitabine to Panc-1 Cells." Journal of pharmaceutics 2013 (January 2013).
Website
http://hdl.handle.net/10161/13734
PMID
26167335
Source
epmc
Published In
Journal of Pharmaceutics
Volume
2013
Publish Date
2013

Raman spectroscopic investigation of individual single-walled carbon nanotubes helically wrapped by Ionic, semiconducting polymers

Raman-active vibrational modes of (6,5) chirality-enriched single-walled carbon nanotubes (SWNTs), helically wrapped by semiconducting poly[2,6-{1,5-bis(3-propoxysulfonic acid sodium salt)}naphthylene]ethynylene (PNES), are described in great detail. At an irradiation wavelength of 568.2 nm, the extent to which the environment impacts the nanotube vibrational signature can be probed; in particular, the absence of a G band shift for PNES-[(6,5) SWNT] samples relative to benchmark surfactant-coated nanotubes indicates the lack of any significant charge transfer between the PNES strand and the SWNT skeleton, but electronic spectra provide compelling evidence for polymer-to-SWNT energy transfer. At an irradiation wavelength of 457.9 nm, vibrational modes associated with PNES chains that wrap (6,5) SWNTs are conspicuously enhanced. Under 514.5 nm irradiation, PNES-[(6,5) SWNTs] are not excited in resonance but G and G′ bands associated with these nanohybrids are strongly enhanced, reflecting the excitation of a multiphonon-mediated vibronic transition of the (6,5) SWNT backbone. At a 488.0 nm irradiation wavelength, Raman spectral signatures of both the PNES polymer and the vibronically excited (6,5) SWNT skeleton through one-phonon-assisted processes are pronounced, demonstrating that a specific SWNT chirality and the corresponding semiconducting polymer helically wrapped about its surface can be probed using an excitation wavelength that does not resonantly excite the SWNT structure. © 2013 American Chemical Society.

Authors
Bonhommeau, S; Deria, P; Glesner, MG; Talaga, D; Najjar, S; Belin, C; Auneau, L; Trainini, S; Therien, MJ; Rodriguez, V
MLA Citation
Bonhommeau, S, Deria, P, Glesner, MG, Talaga, D, Najjar, S, Belin, C, Auneau, L, Trainini, S, Therien, MJ, and Rodriguez, V. "Raman spectroscopic investigation of individual single-walled carbon nanotubes helically wrapped by Ionic, semiconducting polymers." Journal of Physical Chemistry C 117.28 (2013): 14840-14849.
Source
scival
Published In
The Journal of Physical Chemistry C
Volume
117
Issue
28
Publish Date
2013
Start Page
14840
End Page
14849
DOI
10.1021/jp4037606

Dual energy converting nano-phosphors: upconversion luminescence and X-ray excited scintillation from a single composition of lanthanide-doped yttrium oxide.

We report an upconverting nanomaterial composition, [Y(2)O(3); Yb (2%), Er (1%)], that converts both X-ray and high-fluence NIR irradiation to visible light. This composition is compared to a higher Yb(3+) doped composition, [Y(2)O(3); Yb (10%), Er (1%)], that displays diminished visible X-ray scintillation, but shows enhanced red wavelength centered upconversion emission. These nanocrystals have been characterized by TEM, X-ray diffraction, power-dependent upconversion luminescence, and X-ray scintillation spectroscopy. We further demonstrate that lithium ion doping of the [Y(2)O(3); Yb (2%), Er (1%)] nanoscale composition leads to enhanced X-ray and NIR excited emission intensities through the production of nanoparticles that feature slightly enhanced sizes and increased crystallinity.

Authors
Stanton, IN; Ayres, JA; Therien, MJ
MLA Citation
Stanton, IN, Ayres, JA, and Therien, MJ. "Dual energy converting nano-phosphors: upconversion luminescence and X-ray excited scintillation from a single composition of lanthanide-doped yttrium oxide." Dalton Trans 41.38 (October 14, 2012): 11576-11578.
PMID
22940914
Source
pubmed
Published In
Dalton Transactions
Volume
41
Issue
38
Publish Date
2012
Start Page
11576
End Page
11578
DOI
10.1039/c2dt31616a

Tailoring porphyrin-based electron acceptors for organic photovoltaics

Authors
Rawson, J; Stuart, AC; You, W; Therien, MJ
MLA Citation
Rawson, J, Stuart, AC, You, W, and Therien, MJ. "Tailoring porphyrin-based electron acceptors for organic photovoltaics." August 19, 2012.
PMID
25415459
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
244
Publish Date
2012

Exceptional delocalization of electrons in conjugated porphyrin arrays

Authors
Rawson, J; Angiolillo, PJ; Therien, MJ
MLA Citation
Rawson, J, Angiolillo, PJ, and Therien, MJ. "Exceptional delocalization of electrons in conjugated porphyrin arrays." August 19, 2012.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
244
Publish Date
2012

Understanding the helical wrapping of poly(phenylene-ethynylene) polymers about single-walled carbon nanotubes using molecular simulations

Authors
Von Bargen, CD; MacDermaid, CM; Murrett, CS; Lee, O-S; Therien, MJ; Saven, JG
MLA Citation
Von Bargen, CD, MacDermaid, CM, Murrett, CS, Lee, O-S, Therien, MJ, and Saven, JG. "Understanding the helical wrapping of poly(phenylene-ethynylene) polymers about single-walled carbon nanotubes using molecular simulations." August 19, 2012.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
244
Publish Date
2012

Effect of solvent polarity and electrophilicity on quantum yields and solvatochromic shifts of single-walled carbon nanotube photoluminescence.

In this work, we investigate the impact of the solvation environment on single-walled carbon nanotube (SWCNT) photoluminescence quantum yield and optical transition energies (E(ii)) using a highly charged aryleneethynylene polymer. This novel surfactant produces dispersions in a variety of polar solvents having a wide range of dielectric constants (methanol, dimethyl sulfoxide, aqueous dimethylformamide, and deuterium oxide). Because a common surfactant can be used while maintaining a constant SWCNT-surfactant morphology, we are able to straightforwardly evaluate the impact of the solvation environment upon SWCNT optical properties. We find that (i) the SWCNT quantum yield is strongly dependent on both the polarity and electrophilicity of the solvent and (ii) solvatochromic shifts correlate with the extent of SWCNT solvation. These findings provide a deeper understanding of the environmental dependence of SWCNT excitonic properties and underscore that the solvent provides a tool with which to modulate SWCNT electronic and optical properties.

Authors
Larsen, BA; Deria, P; Holt, JM; Stanton, IN; Heben, MJ; Therien, MJ; Blackburn, JL
MLA Citation
Larsen, BA, Deria, P, Holt, JM, Stanton, IN, Heben, MJ, Therien, MJ, and Blackburn, JL. "Effect of solvent polarity and electrophilicity on quantum yields and solvatochromic shifts of single-walled carbon nanotube photoluminescence." J Am Chem Soc 134.30 (August 1, 2012): 12485-12491.
PMID
22746552
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
134
Issue
30
Publish Date
2012
Start Page
12485
End Page
12491
DOI
10.1021/ja2114618

Quasi-ohmic single molecule charge transport through highly conjugated meso-to-meso ethyne-bridged porphyrin wires.

Understanding and controlling electron transport through functional molecules are of primary importance to the development of molecular scale devices. In this work, the single molecule resistances of meso-to-meso ethyne-bridged (porphinato)zinc(II) structures (PZn(n) compounds), connected to gold electrodes via (4'-thiophenyl)ethynyl termini, are determined using scanning tunneling microscopy-based break junction methods. These experiments show that each α,ω-di[(4'-thiophenyl)ethynyl]-terminated PZn(n) compound (dithiol-PZn(n)) manifests a dual molecular conductance. In both the high and low conductance regimes, the measured resistance across these metal-dithiol-PZn(n)-metal junctions increases in a near linear fashion with molecule length. These results signal that meso-to-meso ethyne-bridged porphyrin wires afford the lowest β value (β = 0.034 Å(-1)) yet determined for thiol-terminated single molecules that manifest a quasi-ohmic resistance dependence across metal-dithiol-PZn(n)-metal junctions.

Authors
Li, Z; Park, T-H; Rawson, J; Therien, MJ; Borguet, E
MLA Citation
Li, Z, Park, T-H, Rawson, J, Therien, MJ, and Borguet, E. "Quasi-ohmic single molecule charge transport through highly conjugated meso-to-meso ethyne-bridged porphyrin wires." Nano Lett 12.6 (June 13, 2012): 2722-2727.
PMID
22500812
Source
pubmed
Published In
Nano Letters
Volume
12
Issue
6
Publish Date
2012
Start Page
2722
End Page
2727
DOI
10.1021/nl2043216

Electronic transport in porphyrin supermolecule-gold nanoparticle assemblies.

Temperature-dependent transport of hybrid structures consisting of gold nanoparticle arrays functionalized by conjugated organic molecules [(4'-thiophenyl)ethynyl-terminated meso-to-meso ethyne-bridged (porphinato)zinc(II) complexes] that possess exceptional optical and electronic properties was characterized. Differential conductance analysis distinguished the functional forms of the temperature and voltage dependences for a range of sample particles and molecular attachments. Thermally assisted tunneling describes transport for all cases and the associated mechanistic parameters can be used to determine the relative roles of activation energy, work function, and so forth. These results provide the basis on which to examine plasmon-influenced conduction in hybrid systems.

Authors
Conklin, D; Nanayakkara, S; Park, T-H; Lagadec, MF; Stecher, JT; Therien, MJ; Bonnell, DA
MLA Citation
Conklin, D, Nanayakkara, S, Park, T-H, Lagadec, MF, Stecher, JT, Therien, MJ, and Bonnell, DA. "Electronic transport in porphyrin supermolecule-gold nanoparticle assemblies." Nano Lett 12.5 (May 9, 2012): 2414-2419.
PMID
22545580
Source
pubmed
Published In
Nano Letters
Volume
12
Issue
5
Publish Date
2012
Start Page
2414
End Page
2419
DOI
10.1021/nl300400a

Photo-responsive polymersomes and oligonucleotide assemblies

Authors
Kamat, NP; Liao, Z; Ruble, BK; Griepenburg, J; Moses, LE; Rawson, J; Robbins, GP; Therien, MJ; Hammer, DA; Dmochowski, IJ
MLA Citation
Kamat, NP, Liao, Z, Ruble, BK, Griepenburg, J, Moses, LE, Rawson, J, Robbins, GP, Therien, MJ, Hammer, DA, and Dmochowski, IJ. "Photo-responsive polymersomes and oligonucleotide assemblies." March 25, 2012.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
243
Publish Date
2012

Acentric 2-D ensembles of D-br-A electron-transfer chromophores via vectorial orientation within amphiphilic n-helix bundle peptides for photovoltaic device applications.

We show that simply designed amphiphilic 4-helix bundle peptides can be utilized to vectorially orient a linearly extended donor-bridge-acceptor (D-br-A) electron transfer (ET) chromophore within its core. The bundle's interior is shown to provide a unique solvation environment for the D-br-A assembly not accessible in conventional solvents and thereby control the magnitudes of both light-induced ET and thermal charge recombination rate constants. The amphiphilicity of the bundle's exterior was employed to vectorially orient the peptide-chromophore complex at a liquid-gas interface, and its ends were tailored for subsequent covalent attachment to an inorganic surface, via a "directed assembly" approach. Structural data, combined with evaluation of the excited state dynamics exhibited by these peptide-chromophore complexes, demonstrate that densely packed, acentrically ordered 2-D monolayer ensembles of such complexes at high in-plane chromophore densities approaching 1/200 Å(2) offer unique potential as active layers in binary heterojunction photovoltaic devices.

Authors
Koo, J; Park, J; Tronin, A; Zhang, R; Krishnan, V; Strzalka, J; Kuzmenko, I; Fry, HC; Therien, MJ; Blasie, JK
MLA Citation
Koo, J, Park, J, Tronin, A, Zhang, R, Krishnan, V, Strzalka, J, Kuzmenko, I, Fry, HC, Therien, MJ, and Blasie, JK. "Acentric 2-D ensembles of D-br-A electron-transfer chromophores via vectorial orientation within amphiphilic n-helix bundle peptides for photovoltaic device applications." Langmuir 28.6 (February 14, 2012): 3227-3238.
PMID
22242787
Source
pubmed
Published In
Langmuir
Volume
28
Issue
6
Publish Date
2012
Start Page
3227
End Page
3238
DOI
10.1021/la205002f

Sensing Membrane Stress with Near IR-Emissive Porphyrins

Authors
Kamat, NP; Liao, Z; Therien, MJ; Dmochowski, IJ; Hammer, DA
MLA Citation
Kamat, NP, Liao, Z, Therien, MJ, Dmochowski, IJ, and Hammer, DA. "Sensing Membrane Stress with Near IR-Emissive Porphyrins." January 31, 2012.
Source
wos-lite
Published In
Biophysical Journal
Volume
102
Issue
3
Publish Date
2012
Start Page
299A
End Page
299A

Composite electronic materials based on poly(3,4-propylenedioxythiophene) and highly charged poly(aryleneethynylene)-wrapped carbon nanotubes for supercapacitors.

Supercapacitor charge storage media were fabricated using the semiconducting polymer poly(3,4-propylenedioxythiophene) (PProDOT) and single-walled carbon nanotubes (SWNTs) that were helically wrapped with ionic, conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES). These PNES-wrapped SWNTs (PNES-SWNTs) enable efficient dispersion of individualized nanotubes in a wide range of organic solvents. PNES-SWNT film-modified Pt electrodes were prepared by drop casting PNES-SWNT suspensions in MeOH; high stability, first-generation PProDOT/PNES/SWNT composites were realized via electropolymerization of the ProDOT parent monomer (3,4-propylenedioxythiophene) in a 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/propylene carbonate solution at the PNES-SWNT-modified electrode. The electrochemical properties of PProDOT and PProDOT/PNES/SWNT single electrodes and devices were examined using cyclic voltammetric methods. The hybrid composites were found to enhance key supercapacitor figures of merit (charge capacity and capacitance) by approximately a factor of 2 relative to those determined for benchmark Type I devices that exploited a classic PProDOT-based electrode material. The charge/discharge stability of the supercapacitors was probed by repeated rounds of cyclic voltammetric evaluation at a minimum depth of discharge of 73%; these experiments demonstrated that the hybrid PProDOT/PNES/SWNT composites retained ~90% of their initial charge capacity after 21,000 charge/discharge cycles, contrasting analogous data obtained for PProDOT-based devices, which showed only 84% retention of their initial charge capacity.

Authors
Rosario-Canales, MR; Deria, P; Therien, MJ; Santiago-Avilés, JJ
MLA Citation
Rosario-Canales, MR, Deria, P, Therien, MJ, and Santiago-Avilés, JJ. "Composite electronic materials based on poly(3,4-propylenedioxythiophene) and highly charged poly(aryleneethynylene)-wrapped carbon nanotubes for supercapacitors." ACS Appl Mater Interfaces 4.1 (January 2012): 102-109.
PMID
22136160
Source
pubmed
Published In
ACS Applied Materials and Interfaces
Volume
4
Issue
1
Publish Date
2012
Start Page
102
End Page
109
DOI
10.1021/am201041p

Investigations on X-ray luminescence CT for small animal imaging.

X-ray Luminescence CT (XLCT) is a hybrid imaging modality combining x-ray and optical imaging in which x-ray luminescent nanophosphors (NPs) are used as emissive imaging probes. NPs are easily excited using common CT energy x-ray beams, and the NP luminescence is efficiently collected using sensitive light based detection systems. XLCT can be recognized as a close analog to fluorescence diffuse optical tomography (FDOT). However, XLCT has remarkable advantages over FDOT due to the substantial excitation penetration depths provided by x-rays relative to laser light sources, long term photo-stability of NPs, and the ability to tune NP emission within the NIR spectral window. Since XCLT uses an x-ray pencil beam excitation, the emitted light can be measured and back-projected along the x-ray path during reconstruction, where the size of the X-ray pencil beam determines the resolution for XLCT. In addition, no background signal competes with NP luminescence (i.e., no auto fluorescence) in XLCT. Currently, no small animal XLCT system has been proposed or tested. This paper investigates an XLCT system built and integrated with a dual source micro-CT system. Two novel sampling paradigms that result in more efficient scanning are proposed and tested via simulations. Our preliminary experimental results in phantoms indicate that a basic CT-like reconstruction is able to recover a map of the NP locations and differences in NP concentrations. With the proposed dual source system and faster scanning approaches, XLCT has the potential to revolutionize molecular imaging in preclinical studies.

Authors
Badea, CT; Stanton, IN; Johnston, SM; Johnson, GA; Therien, MJ
MLA Citation
Badea, CT, Stanton, IN, Johnston, SM, Johnson, GA, and Therien, MJ. "Investigations on X-ray luminescence CT for small animal imaging." United States. 2012.
PMID
23227300
Source
pubmed
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
8313
Publish Date
2012
Start Page
83130T

Design of coupled porphyrin chromophores with unusually large hyperpolarizabilities

Figure Persented: A new series of push-pull porphyrin-based chromophores with unusually large static first hyperpolarizabilities are designed on the basis of coupled-perturbed Hartree-Fock and density functional calculations. The proper combination of critical building blocks, including a ruthenium(II) bisterpyridine complex, proquinoidal thiadiazoloquinoxaline, and (porphinato)zinc(II) units, gives rise to considerable predicted enhancements of the static nonlinear optical (NLO) response, computed to be as large as 11 300 × 10 -30 esu, 2 orders of magnitude larger than the benchmark [5-((4′-(dimethylamino)phenyl)ethynyl)-15-((4″-nitrophenyl)ethynyl) porphinato]zinc(II) chromophore. A two-state model was found to be useful for the qualitative description of the first hyperpolarizabilities in this class of NLO chromophores, which are predicted to have hyperpolarizabilities approaching the fundamental limit predicted to be attainable by empirical theoretical models. © 2012 American Chemical Society.

Authors
Jiang, N; Zuber, G; Keinan, S; Nayak, A; Yang, W; Therien, MJ; Beratan, DN
MLA Citation
Jiang, N, Zuber, G, Keinan, S, Nayak, A, Yang, W, Therien, MJ, and Beratan, DN. "Design of coupled porphyrin chromophores with unusually large hyperpolarizabilities." Journal of Physical Chemistry C 116.17 (2012): 9724-9733.
Source
scival
Published In
The Journal of Physical Chemistry C
Volume
116
Issue
17
Publish Date
2012
Start Page
9724
End Page
9733
DOI
10.1021/jp2115065

Enhanced dispersion of CdSe/MEH-CN-PPV hybrid nanocomposites by in situ polymerization using AEM as photopolymerizable precursor

Colloidal quantum dots (CQDs) can easily become aggregated when blended in a polymer matrix. Although several techniques have been reported to prepare dispersed CQDs in a polymer matrix, the novel approach of this work is to obtain well-dispersed CQD-polymer nanocomposites through the in situ photopolymerization of a third source, thereby broadening the material selection available for such nanocomposites. Therefore, dispersed CQD-polymer nanocomposites were prepared by the photopolymerization of 2-aminoethyl methacrylate hydrochloride (AEM) precursor in a blend of trioctyl phosphine oxidecapped CdSe CQDs and poly(2-methoxy-5-(2'-ethylhexyloxy)- α,α'dicyano-p-xylylidene-alt-2,5-dihexyoxy-p-xylylidene) (MEH-CN-PPV). The photopolymerization of AEM was developed for this work in order to prevent possible decomposition of CQDs induced by introducing metallic catalysts or heat and to eliminate the need for further functionalization of CQDs or polymers. The morphology of the photopolymerized CdSe CQD/MEH-CN-PPV/AEM was corroborated by direct observation of the quantum dot dispersion in the resultant sphere-shaped structures via transmission electron microscopy. Photoluminescence quenching and shorter photoluminescence decay lifetime of the MEHCN- PPV in the photopolymerized nanocomposite were observed, indicating that the photopolymerized CdSe CQD/ MEH-CN-PPV/AEM nanocomposite has an enhanced energy transfer efficiency in comparison to typical aggregated CdSe quantum dot/MEH-CN-PPV nanocomposites as a result of better dispersion. © Springer-Verlag 2012.

Authors
Park, Y; Park, J; Therien, MJ; Stiff-Roberts, AD
MLA Citation
Park, Y, Park, J, Therien, MJ, and Stiff-Roberts, AD. "Enhanced dispersion of CdSe/MEH-CN-PPV hybrid nanocomposites by in situ polymerization using AEM as photopolymerizable precursor." Colloid and Polymer Science 290.15 (2012): 1501-1509.
Source
scival
Published In
Colloid and Polymer Science
Volume
290
Issue
15
Publish Date
2012
Start Page
1501
End Page
1509
DOI
10.1007/s00396-012-2672-4

Soft biodegradable polymersomes from caprolactone-derived polymers

Polymersomes have promise for advanced theranostic delivery. We report here the design and characterization of a series of block copolymers that assemble into soft, bioresorbable, and non-toxic vesicles. The polymers are based on poly(ethylene glycol)-poly(caprolactone), but the caprolactone (CL) is copolymerized with a second monomer, 1,4,8-trioxaspiro-[4,6]-9-undecanone (TOSUO). Because TOSUO polymers have no crystalline character, copolymerizing TOSUO with CL should reduce the crystallinity of the polymersomes. After synthesizing polymers with different ratios of CL to TOSUO, we found that all copolymers assemble into both micron and nano-metric vesicles. Increasing the TOSUO content of the copolymer reduces the polymer crystalline melting temperature and the area expansion modulus of vesicle membranes. Membranes with partial crystalline structure exhibit hysteresis in the tension versus strain curve during aspiration. Vesicles are not cytotoxic and exhibit first-order release of encapsulated gemcitabine. These materials are promising for the development of deformable, biodegradable polymersomes for biomedical applications. This journal is © 2012 The Royal Society of Chemistry.

Authors
Katz, JS; Eisenbrown, KA; Johnston, ED; Kamat, NP; Rawson, J; Therien, MJ; Burdick, JA; Hammer, DA
MLA Citation
Katz, JS, Eisenbrown, KA, Johnston, ED, Kamat, NP, Rawson, J, Therien, MJ, Burdick, JA, and Hammer, DA. "Soft biodegradable polymersomes from caprolactone-derived polymers." Soft Matter 8.42 (2012): 10853-10862.
Source
scival
Published In
Soft Matter
Volume
8
Issue
42
Publish Date
2012
Start Page
10853
End Page
10862
DOI
10.1039/c2sm26275d

Two-photon accessed excited state absorption in bis(terpyridyl osmium)-(porphinato)zinc

Two-photon absorption properties of a (terpyridyl)osmium-(porphinato)zinc (OsPZnOs) are studied in bulk and waveguides. Integration of OsPZnOs (d>1300GM) in waveguides showed enhanced nonlinear performance and potential for photonic applications. © OSA/ CLEO 2011.

Authors
Chi, SH; Rosenberg, A; Nayak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Flom, SR; Shirk, JS
MLA Citation
Chi, SH, Rosenberg, A, Nayak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, Flom, SR, and Shirk, JS. "Two-photon accessed excited state absorption in bis(terpyridyl osmium)-(porphinato)zinc." Optics InfoBase Conference Papers (December 1, 2011).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2011

Photophysics of a near IR nonlinear absorber for waveguide applications

Photophysics of a zinc porphyrin-based NIR nonlinear absorber are reported. Welloverlapped two-photon absorption and broad triplet excited state absorption result in a strong nonlinear optical response especially useful in waveguide applications. © 2011 OSA.

Authors
Chi, SH; Rosenberg, A; Nayak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Flom, SR; Shirk, JS
MLA Citation
Chi, SH, Rosenberg, A, Nayak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, Flom, SR, and Shirk, JS. "Photophysics of a near IR nonlinear absorber for waveguide applications." Optics InfoBase Conference Papers (December 1, 2011).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2011

Near IR nonlinear optics of an organic supermolecule

Two-photon accessed excited state absorption is shown to be an important mechanism in the near-IR nonlinear response of an organic supermolecule. This mechanism also provides an enhanced nonlinear absorption in an optical waveguide configuration. © 2011 OSA.

Authors
Flom, SR; Chi, SH; Rosenberg, A; Nayak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Shirk, JS
MLA Citation
Flom, SR, Chi, SH, Rosenberg, A, Nayak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, and Shirk, JS. "Near IR nonlinear optics of an organic supermolecule." Optics InfoBase Conference Papers (December 1, 2011).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2011

Dynamics and transient absorption spectral signatures of the single-wall carbon nanotube electronically excited triplet state.

We utilize femtosecond-to-microsecond time domain pump-probe transient absorption spectroscopy to interrogate for the first time the electronically excited triplet state of individualized single-wall carbon nanotubes (SWNTs). These studies exploit (6,5) chirality-enriched SWNT samples and poly[2,6-{1,5-bis(3-propoxysulfonic acid sodium salt)}naphthylene]ethynylene (PNES), which helically wraps the nanotube surface with periodic and constant morphology (pitch length = 10 ± 2 nm), providing a self-assembled superstructure that maintains structural homogeneity in multiple solvents. Spectroscopic interrogation of such PNES-SWNT samples in aqueous and DMSO solvents using E(22) excitation and a white-light continuum probe enables E(11) and E(22) spectral evolution to be monitored concomitantly. Such experiments not only reveal classic SWNT singlet exciton relaxation dynamics and transient absorption signatures but also demonstrate spectral evolution consistent with formation of a triplet exciton state. Transient dynamical studies evince that (6,5) SWNTs exhibit rapid S(1)→T(1) intersystem crossing (ISC) (τ(ISC) ~20 ps), a sharp T(1)→T(n) transient absorption signal (λ(max)(T(1)→T(n)) = 1150 nm; full width at half-maximum ≈ 350 cm(-1)), and a substantial T(1) excited-state lifetime (τ(es) ≈ 15 μs). Consistent with expectations for a triplet exciton state, T(1)-state spectral signatures and T(1)-state formation and decay dynamics for PNES-SWNTs in aqueous and DMSO solvents, as well as those determined for benchmark sodium cholate suspensions of (6,5) SWNTs, are similar; likewise, studies that probe the (3)[(6,5) SWNT]* state in air-saturated solutions demonstrate (3)O(2) quenching dynamics reminiscent of those determined for conjugated aromatic hydrocarbon excited triplet states.

Authors
Park, J; Deria, P; Therien, MJ
MLA Citation
Park, J, Deria, P, and Therien, MJ. "Dynamics and transient absorption spectral signatures of the single-wall carbon nanotube electronically excited triplet state." J Am Chem Soc 133.43 (November 2, 2011): 17156-17159.
PMID
21970339
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
133
Issue
43
Publish Date
2011
Start Page
17156
End Page
17159
DOI
10.1021/ja2079477

Excited state contributions to near infrared nonliner optical response

Authors
Flom, SR; Chi, S-H; Rosenberg, A; Nyak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Shirk, JS
MLA Citation
Flom, SR, Chi, S-H, Rosenberg, A, Nyak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, and Shirk, JS. "Excited state contributions to near infrared nonliner optical response." August 28, 2011.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
242
Publish Date
2011

Sensing membrane stress with near IR-emissive porphyrins.

Probes embedded within a structure can enable prediction of material behavior or failure. Carefully assembled composites that respond intelligently to physical changes within a material could be useful as intrinsic sensors. Molecular rotors are one such tool that can respond optically to physical environmental changes. Here, we propose to use molecular rotors within a polymersome membrane to report membrane stress. Using supermolecular porphyrin-based fluorophores as rotors, we characterize changes in the optical emission of these near-infrared (NIR) emissive probes embedded within the hydrophobic core of the polymersome membrane. The configuration of entrapped fluorophore depends on the available space within the membrane; in response to increased volume, emission is blue shifted. We used this feature to study how shifts in fluorescence correlate to membrane integrity, imparted by membrane stress. We monitored changes in emission of these porphyrin-based fluorophores resulting from membrane stress produced through a range of physical and chemical perturbations, including surfactant-induced lysis, hydrolytic lysis, thermal degradation, and applied stress by micropipette aspiration. This paper comprehensively illustrates the potential for supermolecular porphyrin-based fluorophores to detect intrinsic physical changes in a wide variety of environments, and suggests how molecular rotors may be used in soft materials science and biology as sensors.

Authors
Kamat, NP; Liao, Z; Moses, LE; Rawson, J; Therien, MJ; Dmochowski, IJ; Hammer, DA
MLA Citation
Kamat, NP, Liao, Z, Moses, LE, Rawson, J, Therien, MJ, Dmochowski, IJ, and Hammer, DA. "Sensing membrane stress with near IR-emissive porphyrins." Proc Natl Acad Sci U S A 108.34 (August 23, 2011): 13984-13989.
PMID
21844376
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
108
Issue
34
Publish Date
2011
Start Page
13984
End Page
13989
DOI
10.1073/pnas.1102125108

Two-photon absorption properties of proquinoidal D-A-D and A-D-A quadrupolar chromophores.

We report the synthesis, one- and two-photon absorption spectroscopy, fluorescence, and electrochemical properties of a series of quadrupolar molecules that feature proquinoidal π-aromatic acceptors. These quadrupolar molecules possess either donor-acceptor-donor (D-A-D) or acceptor-donor-acceptor (A-D-A) electronic motifs, and feature 4-N,N-dihexylaminophenyl, 4-dodecyloxyphenyl, 4-(N,N-dihexylamino)benzo[c][1,2,5]thiadiazolyl or 2,5-dioctyloxyphenyl electron donor moieties and benzo[c][1,2,5]thiadiazole (BTD) or 6,7-bis(3',7'-dimethyloctyl)[1,2,5]thiadiazolo[3,4-g]quinoxaline (TDQ) electron acceptor units. These conjugated structures are highly emissive in nonpolar solvents and exhibit large spectral red-shifts of their respective lowest energy absorption bands relative to analogous reference compounds that incorporate phenylene components in place of BTD and TDQ moieties. BTD-based D-A-D and A-D-A chromophores exhibit increasing fluorescence emission red-shifts, and a concomitant decrease of the fluorescence quantum yield (Φ(f)) with increasing solvent polarity; these data indicate that electronic excitation augments benzothiadiazole electron density via an internal charge transfer mechanism. The BTD- and TDQ-containing structures exhibit blue-shifted two-photon absorption (TPA) spectra relative to their corresponding one-photon absorption (OPA) spectra, and display high TPA cross sections (>100 GM) within these spectral windows. D-A-D and A-D-A structures that feature more extensive conjugation within this series of compounds exhibit larger TPA cross sections consistent with computational simulation. Factors governing TPA properties of these quadrupolar chromophores are discussed within the context of a three-state model.

Authors
Susumu, K; Fisher, JAN; Zheng, J; Beratan, DN; Yodh, AG; Therien, MJ
MLA Citation
Susumu, K, Fisher, JAN, Zheng, J, Beratan, DN, Yodh, AG, and Therien, MJ. "Two-photon absorption properties of proquinoidal D-A-D and A-D-A quadrupolar chromophores." J Phys Chem A 115.22 (June 9, 2011): 5525-5539.
PMID
21568299
Source
pubmed
Published In
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume
115
Issue
22
Publish Date
2011
Start Page
5525
End Page
5539
DOI
10.1021/jp2000738

Structural and pH dependence of excited state PCET reactions involving reductive quenching of the MLCT excited state of [RuII(bpy)2(bpz)]2+ by hydroquinones.

The proton-coupled electron transfer (PCET) reaction between the bpz-based photoexcited (3)MLCT state of [Ru(II)(bpy)(2)(bpz)](2+) (bpy = 2,2'-bipyridine, bpz = 2,2'-bipyrazine) and a series of substituted hydroquinones (H(2)Q) has been studied by transient absorption (TA) and time-resolved electron paramagnetic resonance (TREPR) spectroscopy at X-band. When the reaction is carried out in a CH(3)CN/H(2)O mixed solvent system with unsubstituted hydroquinone, the neutral semiquinone radical (4a) and its conjugate base, the semiquinone radical anion (4b), are both observed. Variation of the acid strength in the solvent mixture allows the acid/base dependence of the PCET reaction to be investigated. In solutions with very low acid concentrations, TREPR spectra exclusively derived from radical anion 4b are observed, while at very high acid concentrations, the spectrum is assigned to the protonated structure 4a. At intermediate acid concentrations, either a superposition of spectra is observed (slow exchange between 4a and 4b) or substantial broadening in the TREPR spectrum is observed (fast exchange between 4a and 4b). Variation of substituents on the H(2)Q ring substantially alter this acid/base dependence and provide a means to investigate electronic effects on both the ET and PT components of the PCET process. The TA results suggest a change in mechanism from PCET to direct ET quenching in strongly basic solutions and with electron withdrawing groups on the H(2)Q ring system. Changing the ligand on the Ru complex also alters the acid/base dependence of the TREPR spectra through a series of complex equilibria between protonated and deprotonated hydroquinone radicals and anions. The relative intensities of the signals from radical 4a versus 4b can be rationalized quantitatively in terms of these equilibria and the relevant pK(a) values. An observed equilibrium deuterium isotope effect supports the conclusion that the post-PCET HQ(•)/Q(•-) equilibrium is the most important in determining the 4a/4b ratio at early delay times.

Authors
Lebedeva, NV; Schmidt, RD; Concepcion, JJ; Brennaman, MK; Stanton, IN; Therien, MJ; Meyer, TJ; Forbes, MDE
MLA Citation
Lebedeva, NV, Schmidt, RD, Concepcion, JJ, Brennaman, MK, Stanton, IN, Therien, MJ, Meyer, TJ, and Forbes, MDE. "Structural and pH dependence of excited state PCET reactions involving reductive quenching of the MLCT excited state of [RuII(bpy)2(bpz)]2+ by hydroquinones." J Phys Chem A 115.15 (April 21, 2011): 3346-3356.
PMID
21434655
Source
pubmed
Published In
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume
115
Issue
15
Publish Date
2011
Start Page
3346
End Page
3356
DOI
10.1021/jp200381n

The roles of molecular structure and effective optical symmetry in evolving dipolar chromophoric building blocks to potent octopolar nonlinear optical chromophores.

A series of mono-, bis-, tris-, and tetrakis(porphinato)zinc(II) (PZn)-elaborated ruthenium(II) bis(terpyridine) (Ru) complexes have been synthesized in which an ethyne unit connects the macrocycle meso carbon atom to terpyridyl (tpy) 4-, 4'-, and 4''-positions. These supermolecular chromophores, based on the ruthenium(II) [5-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2''-terpyridine)(2+) bis-hexafluorophosphate (RuPZn) archetype, evince strong mixing of the PZn-based oscillator strength with ruthenium terpyridyl charge resonance bands. Potentiometric and linear absorption spectroscopic data indicate that for structures in which multiple PZn moieties are linked via ethynes to a [Ru(tpy)(2)](2+) core, little electronic coupling is manifest between PZn units, regardless of whether they are located on the same or opposite tpy ligand. Congruent with these experiments, pump-probe transient absorption studies suggest that the individual RuPZn fragments of these structures exhibit, at best, only modest excited-state electronic interactions that derive from factors other than the dipole-dipole interactions of these strong oscillators; this approximate independent character of the component RuPZn oscillators enables fabrication of nonlinear optical (NLO) multipoles with extraordinary hyperpolarizabilities. Dynamic hyperpolarizability (β(λ)) values and depolarization ratios (ρ) were determined from hyper-Rayleigh light scattering (HRS) measurements carried out at an incident irradiation wavelength (λ(inc)) of 1300 nm. The depolarization ratio data provide an experimental measure of chromophore optical symmetry; appropriate coupling of multiple charge-transfer oscillators produces structures having enormous averaged hyperpolarizabilities (β(HRS) values), while evolving the effective chromophore symmetry from purely dipolar (e.g., Ru(tpy)[4-(Zn-porphyrin)ethynyl-tpy](PF(6))(2), β(HRS) = 1280 × 10(-30) esu, ρ = 3.8; Ru(tpy)[4'-(Zn-porphyrin)ethynyl-tpy](PF(6))(2), β(HRS) = 2100 × 10(-30) esu, ρ = 3.8) to octopolar (e.g., Ru[4,4''-bis(Zn-porphyrin)ethynyl-tpy](2)(PF(6))(2), β(HRS) = 1040 × 10(-30) esu, ρ = 1.46) via structural motifs that possess intermediate values of the depolarization ratio. The chromophore design roadmap provided herein gives rise to octopolar supermolecules that feature by far the largest off-diagonal octopolar first hyperpolarizability tensor components ever reported, with the effectively octopolar Ru[4,4''-bis(Zn-porphyrin)ethynyl-tpy](2)(PF(6))(2) possessing a β(HRS) value at 1300 nm more than a factor of 3 larger than that determined for any chromophore having octopolar symmetry examined to date. Because NLO octopoles possess omnidirectional NLO responses while circumventing the electrostatic interactions that drive bulk-phase centrosymmetry for NLO dipoles at high chromophore concentrations, the advent of octopolar NLO chromophores having vastly superior β(HRS) values at technologically important wavelengths will motivate new experimental approaches to achieve acentric order in both bulk-phase and thin film structures.

Authors
Ishizuka, T; Sinks, LE; Song, K; Hung, S-T; Nayak, A; Clays, K; Therien, MJ
MLA Citation
Ishizuka, T, Sinks, LE, Song, K, Hung, S-T, Nayak, A, Clays, K, and Therien, MJ. "The roles of molecular structure and effective optical symmetry in evolving dipolar chromophoric building blocks to potent octopolar nonlinear optical chromophores." J Am Chem Soc 133.9 (March 9, 2011): 2884-2896.
PMID
21322603
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
133
Issue
9
Publish Date
2011
Start Page
2884
End Page
2896
DOI
10.1021/ja105004k

Effects of Membrane Rheology on Leuko-polymersome Adhesion to Inflammatory Ligands.

A strategy for treating inflammatory disease is to create micro-particles with the adhesive properties of leukocytes. The underlying rheology of deformable adhesive microspheres would be an important factor in the adhesive performance of such particles. In this work the effect of particle deformability on the selectin-mediated rolling of polymer vesicles (polymersomes) is evaluated. The rheology of the polymersome membrane was modulated by cross-linking unsaturated side-chains within the hydrophobic core of the membrane. Increased membrane rigidity resulted in decreased rates of particle recruitment rather than decreased average rolling velocities. Reflective interference contrast microscopy of rolling vesicles confirmed that neither flaccid nor rigid vesicles sustained close contacts with the substrate during rolling adhesion. A variable-shear rate parallel-plate flow chamber was employed to evaluate individual vesicles rolling on substrates under different flow conditions. Analysis of the trajectories of single flaccid vesicles revealed several distinct populations of rolling vesicles; however, some of these populations disappear when the vesicle membranes are made rigid. This work shows that membrane mechanics affects the capture, but not the rolling dynamics, of adherent leuko-polymersomes.

Authors
Robbins, GP; Lee, D; Katz, JS; Frail, PR; Therien, MJ; Crocker, JC; Hammer, DA
MLA Citation
Robbins, GP, Lee, D, Katz, JS, Frail, PR, Therien, MJ, Crocker, JC, and Hammer, DA. "Effects of Membrane Rheology on Leuko-polymersome Adhesion to Inflammatory Ligands." Soft Matter 7.2 (January 1, 2011): 769-779.
PMID
23139698
Source
pubmed
Published In
Soft Matter
Volume
7
Issue
2
Publish Date
2011
Start Page
769
End Page
779
DOI
10.1039/C0SM00554A

Controlling polarization dependent reactions to fabricate multi-component functional nanostructures

In spite of novel lithographic processes that enable new approaches to fabricating materials, directed assembly of multi-component hybrid devices remains a challenge. Ferroelectric nanolithography exploits polarization dependent surface interactions to pattern nanoparticles, but the factors that control the particle size and distribution are not sufficiently well understood to produce hybrid nanostructures. Here the effects of photon energy, photon flux, and polarization vector orientation on ferroelectric domain specific photoreactions are quantified, leading to an understanding of the nanoparticle deposition mechanism. Patterned nanoparticle arrays functionalized with optically active porphyrin complexes are configured into optoelectronic devices. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Authors
Conklin, D; Park, T-H; Nanayakkara, S; Therien, MJ; Bonnell, DA
MLA Citation
Conklin, D, Park, T-H, Nanayakkara, S, Therien, MJ, and Bonnell, DA. "Controlling polarization dependent reactions to fabricate multi-component functional nanostructures." Advanced Functional Materials 21.24 (2011): 4712-4718.
Source
scival
Published In
Advanced Functional Materials
Volume
21
Issue
24
Publish Date
2011
Start Page
4712
End Page
4718
DOI
10.1002/adfm.201101673

Near IR nonlinear absorption of an organic supermolecule [Invited]

The photophysics of bis(terpyridyl)osmium-(porphinato)zinc-bis(terpyridyl)osmium (OsPZnOs), a D-π-A-π-D symmetric supermolecule, were investigated in the femtosecond and nanosecond regimes. The supermolecule exhibits a two-photon absorption (δpeak ~900 GM) in the near IR (900-1300 nm) and optical pumping by two-photon absorption leads to a broad excited state absorption (σpeak ~1.1 × 10-16 cm2) in the same near IR region. Since the excited state has a long lifetime, OsPZnOs exhibits a strong nanosecond nonlinear absorption in this region. That nonlinear absorption is substantially enhanced when OsPZnOs is incorporated into a multimode waveguide. When two-photon pumping is the dominant mechanism, an additional enhancement of up to ~100 × in the nonlinear absorption is observed in a microchannel waveguide. OsPZnOs is a promising material for photonic applications such as optical noise suppression and optical limiting in the near IR. © 2011 Optical Society of America.

Authors
Chi, S-H; Rosenberg, A; Nayak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Pong, RGS; Shirk, JS; Flom, SR
MLA Citation
Chi, S-H, Rosenberg, A, Nayak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, Pong, RGS, Shirk, JS, and Flom, SR. "Near IR nonlinear absorption of an organic supermolecule [Invited]." Optical Materials Express 1.7 (2011): 1383-1392.
Source
scival
Published In
Optical Materials Express
Volume
1
Issue
7
Publish Date
2011
Start Page
1383
End Page
1392
DOI
10.1364/OME.1.001383

Electron transfer reactions of rigid, cofacially compressed, π-stacked porphyrin-bridge-quinone systems

A 1,8-naphthyl pillaring motif can be utilized to enforce sub van der Waals interplanar separations between juxtaposed porphyryl, aromatic bridge, and quinonyl components of donor-spacer-acceptor (D-Sp-A) compounds. Such structures, synthesized via metal-mediated cross-coupling of appropriately functionalized (porphinato)zinc(II), arene, and quinone precursors, manifest unusual conformational rigidity in the condensed phase, and significant electronic communication between the cofacially aligned D, Sp, and A components. NMR experiments provide rigorous determination of the ambient temperature structures of these species in solution, while computational methods offer insight into the fragment molecular orbital interactions that give rise to the strong D-A coupling evident in these assemblies. The distance-, temperature-, and solvent-dependences of photoinduced charge separation (CS) and thermal charge recombination (CR) rate constants in these systems have been evaluated using femtosecond visible pump/vis-NIR probe and visible pump/mid-IR probe transient dynamical methods. These experiments: (i) demonstrate that simple aromatic building blocks like benzene, which are characterized by highly stabilized filled molecular orbitals and large HOMO-LUMO gaps, provide substantial D-A electronic coupling when organized within a π-stacked structural motif that features a modest degree of arene-arene interplanar compression; (ii) assess directly the degree of ground and excited state charge transfer (CT) in these donor-spacer-acceptor (D-Sp-A) structures, (iii) reveal unusual CS dynamics from vibrationally relaxed and unrelaxed S1 states, and (iv) show a photoinduced CS mechanistic transition from the nonadiabatic to the solvent-controlled adiabatic regime, to one where CS becomes decoupled from solvent dynamics and is determined by the extent to which the vibrationally unrelaxed S1 state is populated. © 2011 Elsevier B.V.

Authors
Kang, YK; Iovine, PM; Therien, MJ
MLA Citation
Kang, YK, Iovine, PM, and Therien, MJ. "Electron transfer reactions of rigid, cofacially compressed, π-stacked porphyrin-bridge-quinone systems." Coordination Chemistry Reviews 255.7-8 (2011): 804-824.
Source
scival
Published In
Coordination Chemistry Reviews
Volume
255
Issue
7-8
Publish Date
2011
Start Page
804
End Page
824
DOI
10.1016/j.ccr.2010.12.011

Two-photon accessed excited state absorption in bis(terpyridyl osmium)-(porphinato)zinc

Two-photon absorption properties of a (terpyridyl)osmium-(porphinato)zinc (OsPZnOs) are studied in bulk and waveguides. Integration of OsPZnOs (δ>1300GM) in waveguides showed enhanced nonlinear performance and potential for photonic applications. © 2011 OSA.

Authors
Chi, S-H; Rosenberg, A; Nayak, A; Duncan, TV; Therien, MJ; Butler, JJ; Montgomery, SR; Beadie, G; Flom, SR; Shirk, JS
MLA Citation
Chi, S-H, Rosenberg, A, Nayak, A, Duncan, TV, Therien, MJ, Butler, JJ, Montgomery, SR, Beadie, G, Flom, SR, and Shirk, JS. "Two-photon accessed excited state absorption in bis(terpyridyl osmium)-(porphinato)zinc." 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011 (2011).
Source
scival
Published In
2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011
Publish Date
2011

Erratum: Supermolecular-chromophore-sensitized near-infrared-to-visible photon upconversion (Journal of the American Chemical Society (2010) 132 (14203-14211) DOI: 10.1021/ja105510k)

Authors
Singh-Rachford, TN; Nayak, A; Muro-Small, ML; Goeb, S; Therien, MJ; Castellano, FN
MLA Citation
Singh-Rachford, TN, Nayak, A, Muro-Small, ML, Goeb, S, Therien, MJ, and Castellano, FN. "Erratum: Supermolecular-chromophore-sensitized near-infrared-to-visible photon upconversion (Journal of the American Chemical Society (2010) 132 (14203-14211) DOI: 10.1021/ja105510k)." Journal of the American Chemical Society 133.8 (2011): 2791--.
Source
scival
Published In
Journal of the American Chemical Society
Volume
133
Issue
8
Publish Date
2011
Start Page
2791-
DOI
10.1021/ja200045y

Single-chain, helical wrapping of individualized, single-walled carbon nanotubes by ionic poly(aryleneethynylene)s: New compositions for photoinduced charge transfer reactions and photovoltaic applications

Amphiphilic, linear, semi-conducting aryleneethynylene polymers such as poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) and poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}napthylene]ethynylene (PNES) efficiently disperse single-walled carbon nanotubes (SWNTs) under ultra-sonication conditions into the aqueous phase. Vis-NIR absorption spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) demonstrate that these solubilized SWNTs are individualized. AFM and TEM data reveal that the interaction of PPES and PNES with SWNTs gives rise to a self-assembled superstructures in which a polymer monolayer helically wraps the nanotube surface; the observed PPES and PNES pitch lengths confirm structural predictions made via MD simulations. Following appropriate metatheses reactions, these self-assembled polymer-nanotube systems can be dissolved in organic solvents; electronic spectroscopy, transient absorption studies, as well as AFM and TEM data confirm that the PNES/PPES helical wrapping structure observed for individualized SWNTs in aqueous solution persists in nonaqueous media. These well-defined nanotube-semi-conducting polymer hybrid structures can be further engineered to serve as electron transport elements in excitonic solar cells and function as electron acceptors in electron transfer reactions involving photoactivatable redox centers anchored to the SWNT backbone.

Authors
Deria, P; Glesner, MG; Kang, YK; Lee, O-S; Sinks, L; Kim, SH; Park, T-H; Bonnell, DA; Saven, JG; Therien, MJ
MLA Citation
Deria, P, Glesner, MG, Kang, YK, Lee, O-S, Sinks, L, Kim, SH, Park, T-H, Bonnell, DA, Saven, JG, and Therien, MJ. "Single-chain, helical wrapping of individualized, single-walled carbon nanotubes by ionic poly(aryleneethynylene)s: New compositions for photoinduced charge transfer reactions and photovoltaic applications." ACS National Meeting Book of Abstracts (2011).
Source
scival
Published In
ACS National Meeting Book of Abstracts
Publish Date
2011

Excitation of highly conjugated (porphinato)palladium(II) and (porphinato)platinum(II) oligomers produces long-lived, triplet states at unit quantum yield that absorb strongly over broad spectral domains of the NIR.

Transient dynamical studies of bis[(5,5'-10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)palladium(II)]ethyne (PPd(2)), 5,15-bis{[(5'-10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)palladium(II)]ethynyl}(10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)palladium(II) (PPd(3)), bis[(5,5'-10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)platinum(II)]ethyne (PPt(2)), and 5,15-bis{[(5'-10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)platinum(II)]ethynyl}(10,20-bis(2,6-bis(3,3-dimethylbutoxy)phenyl)porphinato)platinum(II) (PPt(3)) show that the electronically excited triplet states of these highly conjugated supermolecular chromophores can be produced at unit quantum yield via fast S(1) → T(1) intersystem crossing dynamics (τ(isc): 5.2-49.4 ps). These species manifest high oscillator strength T(1) → T(n) transitions over broad NIR spectral windows. The facts that (i) the electronically excited triplet lifetimes of these PPd(n) and PPt(n) chromophores are long, ranging from 5 to 50 μs, and (ii) the ground and electronically excited absorptive manifolds of these multipigment ensembles can be extensively modulated over broad spectral domains indicate that these structures define a new precedent for conjugated materials featuring low-lying π-π* electronically excited states for NIR optical limiting and related long-wavelength nonlinear optical (NLO) applications.

Authors
Duncan, TV; Frail, PR; Miloradovic, IR; Therien, MJ
MLA Citation
Duncan, TV, Frail, PR, Miloradovic, IR, and Therien, MJ. "Excitation of highly conjugated (porphinato)palladium(II) and (porphinato)platinum(II) oligomers produces long-lived, triplet states at unit quantum yield that absorb strongly over broad spectral domains of the NIR." J Phys Chem B 114.45 (November 18, 2010): 14696-14702.
Website
http://hdl.handle.net/10161/4070
PMID
20527945
Source
pubmed
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
114
Issue
45
Publish Date
2010
Start Page
14696
End Page
14702
DOI
10.1021/jp102901u

De novo design and molecular assembly of a transmembrane diporphyrin-binding protein complex.

The de novo design of membrane proteins remains difficult despite recent advances in understanding the factors that drive membrane protein folding and association. We have designed a membrane protein PRIME (PoRphyrins In MEmbrane) that positions two non-natural iron diphenylporphyrins (Fe(III)DPP's) sufficiently close to provide a multicentered pathway for transmembrane electron transfer. Computational methods previously used for the design of multiporphyrin water-soluble helical proteins were extended to this membrane target. Four helices were arranged in a D(2)-symmetrical bundle to bind two Fe(II/III) diphenylporphyrins in a bis-His geometry further stabilized by second-shell hydrogen bonds. UV-vis absorbance, CD spectroscopy, analytical ultracentrifugation, redox potentiometry, and EPR demonstrate that PRIME binds the cofactor with high affinity and specificity in the expected geometry.

Authors
Korendovych, IV; Senes, A; Kim, YH; Lear, JD; Fry, HC; Therien, MJ; Blasie, JK; Walker, FA; Degrado, WF
MLA Citation
Korendovych, IV, Senes, A, Kim, YH, Lear, JD, Fry, HC, Therien, MJ, Blasie, JK, Walker, FA, and Degrado, WF. "De novo design and molecular assembly of a transmembrane diporphyrin-binding protein complex." J Am Chem Soc 132.44 (November 10, 2010): 15516-15518.
Website
http://hdl.handle.net/10161/4046
PMID
20945900
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
44
Publish Date
2010
Start Page
15516
End Page
15518
DOI
10.1021/ja107487b

Phase transfer catalysts drive diverse organic solvent solubility of single-walled carbon nanotubes helically wrapped by ionic, semiconducting polymers.

Use of phase transfer catalysts such as 18-crown-6 enables ionic, linear conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES) to efficiently disperse single-walled carbon nanotubes (SWNTs) in multiple organic solvents under standard ultrasonication methods. Steady-state electronic absorption spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) reveal that these SWNT suspensions are composed almost exclusively of individualized tubes. High-resolution TEM and AFM data show that the interaction of PNES with SWNTs in both protic and aprotic organic solvents provides a self-assembled superstructure in which a PNES monolayer helically wraps the nanotube surface with periodic and constant morphology (observed helical pitch length = 10 ± 2 nm); time-dependent examination of these suspensions indicates that these structures persist in solution over periods that span at least several months. Pump-probe transient absorption spectroscopy reveals that the excited state lifetimes and exciton binding energies of these well-defined nanotube-semiconducting polymer hybrid structures remain unchanged relative to analogous benchmark data acquired previously for standard sodium dodecylsulfate (SDS)-SWNT suspensions, regardless of solvent. These results demonstrate that the use of phase transfer catalysts with ionic semiconducting polymers that helically wrap SWNTs provide well-defined structures that solubulize SWNTs in a wide range of organic solvents while preserving critical nanotube semiconducting and conducting properties.

Authors
Deria, P; Sinks, LE; Park, T-H; Tomezsko, DM; Brukman, MJ; Bonnell, DA; Therien, MJ
MLA Citation
Deria, P, Sinks, LE, Park, T-H, Tomezsko, DM, Brukman, MJ, Bonnell, DA, and Therien, MJ. "Phase transfer catalysts drive diverse organic solvent solubility of single-walled carbon nanotubes helically wrapped by ionic, semiconducting polymers." Nano Lett 10.10 (October 13, 2010): 4192-4199.
Website
http://hdl.handle.net/10161/4096
PMID
20809609
Source
pubmed
Published In
Nano Letters
Volume
10
Issue
10
Publish Date
2010
Start Page
4192
End Page
4199
DOI
10.1021/nl102540c

Supermolecular-chromophore-sensitized near-infrared-to-visible photon upconversion.

Selective near-IR (NIR) excitation (780 nm) of the conjugated supermolecule ruthenium(II) [15-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-bis[(5,5',-10,20-di(2',6'-bis(3,3-dimethylbutoxy)phenyl)porphinato)zinc(II)]ethyne][4'-pyrrolidin-1-yl-2,2';6',2''-terpyridine] bis(hexafluorophosphate) (Pyr(1)RuPZn(2)) in solutions containing N,N-bis(ethylpropyl)perylene-3,4,9,10-tetracarboxylicdiimide (PDI) or tetracene gives rise to a substantial anti-Stokes energy gain (PDI, 0.70 eV; tetracene, 0.86 eV). Experimental data clearly demonstrate that this upconverted fluorescence signal is produced via Pyr(1)RuPZn(2)-sensitized triplet-triplet annihilation (TTA) photochemistry. The TTA process was confirmed by the quadratic dependence of the integrated (1)PDI* emission centered at 541 nm derived from 780 nm laser excitation. The T(1)→T(n) excited state absorption decay of Pyr(1)RuPZn(2), monitored at 900 nm as a function of PDI concentration, revealed Stern-Volmer and bimolecular quenching constants of 10 048 M(-1) and 5.9 × 10(8) M(-1) s(-1), respectively, for the PDI triplet sensitization process. The T(1)→T(n) PDI extinction coefficient at 560 nm (ε(T) = 6.6 × 10(4) M(-1) cm(-1)) was determined through the triplet energy transfer method utilizing anthracene as the donor chromophore. (3)PDI* transient triplet absorption dynamics observed as a function of 485 nm incident nanosecond pump laser fluence demonstrate a bimolecular (3)PDI*-(3)PDI* TTA rate constant (k(TT) = 1.0 ± 0.2 × 10(9) M(-1) s(-1)). The maximum quantum yield of the supermolecule-sensitized PDI upconverted emission (Φ(UC) = 0.0075 ± 0.0002) was determined relative to [Os(phen)(3)][PF(6)](2) at an incident laser power of 22 mW at 780 nm. This study successfully demonstrates NIR-to-visible photon upconversion and achieves a new record anti-Stokes shift of 0.86 eV for sensitized TTA, using the supermolecular Pyr(1)RuPZn(2)sensitizer. The stability of the Pyr(1)RuPZn(2)/PDI chromophore combination is readily apparent as continuous irradiation at 780 nm produces 541 nm centered fluorescence with no significant decrease in intensity measured over time domains exceeding several hours. The molecular components of these NIR-to-vis upconverting compositions illustrate that substantial anti-Stokes energy gains via a TTA process can be effortlessly realized.

Authors
Singh-Rachford, TN; Nayak, A; Muro-Small, ML; Goeb, S; Therien, MJ; Castellano, FN
MLA Citation
Singh-Rachford, TN, Nayak, A, Muro-Small, ML, Goeb, S, Therien, MJ, and Castellano, FN. "Supermolecular-chromophore-sensitized near-infrared-to-visible photon upconversion." J Am Chem Soc 132.40 (October 13, 2010): 14203-14211.
Website
http://hdl.handle.net/10161/4044
PMID
20828165
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
40
Publish Date
2010
Start Page
14203
End Page
14211
DOI
10.1021/ja105510k

Tunable leuko-polymersomes that adhere specifically to inflammatory markers.

The polymersome, a fully synthetic cell mimetic, is a tunable platform for drug delivery vehicles to detect and treat disease (theranostics). Here, we design a leuko-polymersome, a polymersome with the adhesive properties of leukocytes, which can effectively bind to inflammatory sites under flow. We hypothesize that optimal leukocyte adhesion can be recreated with ligands that mimic receptors of the two major leukocyte molecular adhesion pathways, the selectins and the integrins. Polymersomes functionalized with sialyl Lewis X and an antibody against ICAM-1 adhere avidly and selectively to surfaces coated with inflammatory adhesion molecules P-selectin and ICAM-1 under flow. We find that maximal adhesion occurs at intermediate densities of both sialyl Lewis X and anti-ICAM-1, owing to synergistic binding effects between the two ligands. Leuko-polymersomes bearing these two receptor mimetics adhere under physiological shear rates to inflamed endothelium in an in vitro flow chamber at a rate 7.5 times higher than those to uninflamed endothelium. This work clearly demonstrates that polymersomes bearing only a single ligand bind less avidly and with lower selectivity, thus suggesting proper mimicry of leukocyte adhesion requires contributions from both pathways. This work establishes a basis for the design of polymersomes for targeted drug delivery in inflammation.

Authors
Robbins, GP; Saunders, RL; Haun, JB; Rawson, J; Therien, MJ; Hammer, DA
MLA Citation
Robbins, GP, Saunders, RL, Haun, JB, Rawson, J, Therien, MJ, and Hammer, DA. "Tunable leuko-polymersomes that adhere specifically to inflammatory markers." Langmuir 26.17 (September 7, 2010): 14089-14096.
PMID
20704280
Source
pubmed
Published In
Langmuir
Volume
26
Issue
17
Publish Date
2010
Start Page
14089
End Page
14096
DOI
10.1021/la1017032

Tunable Leuko-polymersomes That Adhere Specifically to Inflammatory Markers

Authors
Robbins, GP; Saunders, RL; Haun, JB; Rawson, J; Therien, MJ; Hammer, DA
MLA Citation
Robbins, GP, Saunders, RL, Haun, JB, Rawson, J, Therien, MJ, and Hammer, DA. "Tunable Leuko-polymersomes That Adhere Specifically to Inflammatory Markers." LANGMUIR 26.17 (September 7, 2010): 14089-14096.
Website
http://hdl.handle.net/10161/3993
Source
wos-lite
Published In
Langmuir
Volume
26
Issue
17
Publish Date
2010
Start Page
14089
End Page
14096
DOI
10.1021/la1017032

A Generalized System for Photo-Responsive Membrane Rupture in Polymersomes.

Polymersomes are vesicles whose membranes are comprised of self-assembled block co-polymers. We recently showed that co-encapsulating conjugated multi-porphyrin dyes in a polymersome membrane with ferritin protein in the aqueous lumen confers photo-lability to the polymersome. In the present study, we illustrate that the photo-lability can be extended to vesicles containing dextran, an inert and inexpensive polysaccharide, as the luminal solute. Here we explore how structural features of the polymersome/porphyrin/dextran composite affect its photo-response. Increasing dextran molecular weight, decreasing block copolymer molecular weight, and altering fluorophore-membrane interactions results in increasing the photo-responsiveness of the polymersomes. Amphiphilic interactions of the luminal encapsulant with the membrane coupled with localized heat production in the hydrophobic bilayer likely cause differential thermal expansion in the membrane and the subsequent membrane rupture. This study suggests a general approach to impart photo-responsiveness to any biomimetic vesicle system without chemical modification, as well as a simple, bio-inert method for constructing photo-sensitive carriers for controlled release of encapsulants.

Authors
Kamat, NP; Robbins, GP; Rawson, JS; Therien, MJ; Dmochowski, IJ; Hammer, DA
MLA Citation
Kamat, NP, Robbins, GP, Rawson, JS, Therien, MJ, Dmochowski, IJ, and Hammer, DA. "A Generalized System for Photo-Responsive Membrane Rupture in Polymersomes." Adv Funct Mater 20.16 (August 23, 2010): 2588-2596.
PMID
21709747
Source
pubmed
Published In
Advanced Functional Materials
Volume
20
Issue
16
Publish Date
2010
Start Page
2588
End Page
2596
DOI
10.1002/adfm.201000659

Upconversion luminescence and X-ray-excited optical luminescence (XEOL) of lanthanide doped Yttrium oxide nanocrystals

Authors
Stanton, IN; Ayres, JA; Therien, MJ
MLA Citation
Stanton, IN, Ayres, JA, and Therien, MJ. "Upconversion luminescence and X-ray-excited optical luminescence (XEOL) of lanthanide doped Yttrium oxide nanocrystals." August 22, 2010.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
240
Publish Date
2010

Novel, lanthanide-based nanoparticles for NIR to UV energy conversion

Authors
Ayres, JA; Stanton, IN; Therien, MJ
MLA Citation
Ayres, JA, Stanton, IN, and Therien, MJ. "Novel, lanthanide-based nanoparticles for NIR to UV energy conversion." August 22, 2010.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
240
Publish Date
2010

Control of the orientational order and nonlinear optical response of the "push-pull" chromophore RuPZn via specific incorporation into densely packed monolayer ensembles of an amphiphilic four-helix bundle peptide: characterization of the peptide-chromophore complexes.

"Push-pull" chromophores based on extended pi-electron systems have been designed to exhibit exceptionally large molecular hyperpolarizabilities. We have engineered an amphiphilic four-helix bundle peptide to vectorially incorporate such hyperpolarizable chromophores having a metalloporphyrin moiety, with high specificity into the interior core of the bundle. The amphiphilic exterior of the bundle facilitates the formation of densely packed monolayer ensembles of the vectorially oriented peptide-chromophore complexes at the liquid-gas interface. Chemical specificity designed into the ends of the bundle facilitates the subsequent covalent attachment of these monolayer ensembles onto the surface of an inorganic substrate. In this article, we describe the structural characterization of these monolayer ensembles at each stage of their fabrication for one such peptide-chromophore complex designated as AP0-RuPZn. In the accompanying article, we describe the characterization of their macroscopic nonlinear optical properties.

Authors
Krishnan, V; Tronin, A; Strzalka, J; Fry, HC; Therien, MJ; Blasie, JK
MLA Citation
Krishnan, V, Tronin, A, Strzalka, J, Fry, HC, Therien, MJ, and Blasie, JK. "Control of the orientational order and nonlinear optical response of the "push-pull" chromophore RuPZn via specific incorporation into densely packed monolayer ensembles of an amphiphilic four-helix bundle peptide: characterization of the peptide-chromophore complexes." J Am Chem Soc 132.32 (August 18, 2010): 11083-11092.
Website
http://hdl.handle.net/10161/4040
PMID
20698674
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
32
Publish Date
2010
Start Page
11083
End Page
11092
DOI
10.1021/ja1010702

Control of the orientational order and nonlinear optical response of the "push-pull" chromophore RuPZn via specific incorporation into densely packed monolayer ensembles of an amphiphilic 4-helix bundle peptide: second harmonic generation at high chromophore densities.

The macroscopic nonlinear optical response of the "push-pull" chromophore RuPZn incorporated into a single monolayer of the amphiphilic 4-helix bundle peptide (AP0) covalently attached to a solid substrate at high in-plane density has been measured. The second-order susceptibility, chi(zzz), was found to be in the range of approximately 15 x 10(-9) esu, consistent with a coherent sum of the nonlinear contributions from the individual chromophores (beta) as previously measured in isotropic solution through hyper-Rayleigh scattering as well as estimated from theoretical calculations. The microscopic hyperpolarizability of the RuPZn chromophore is preserved upon incorporation into the peptide monolayer, suggesting that the chromophore-chromophore interactions in the densely packed ensemble do not substantially affect the first-order molecular hyperpolarizability. The polarization angle dependence of the second harmonic signal reveals that the chromophore is vectorially oriented in the two-dimensional ensemble. Analysis of the order parameter together with information obtained from grazing incidence X-ray diffraction help in determining the chromophore orientation within the AP0-RuPZn monolayer. Taking into account an average pitch angle of approximately 20 degrees characterizing the coiled-coil structure of the peptide bundle, the width of the bundle's tilt angle distribution should be sigma < or = 20 degrees, resulting in a mean value of the tilt angle 23 degrees < or = theta(0) < or = 37 degrees.

Authors
Gonella, G; Dai, H-L; Fry, HC; Therien, MJ; Krishnan, V; Tronin, A; Blasie, JK
MLA Citation
Gonella, G, Dai, H-L, Fry, HC, Therien, MJ, Krishnan, V, Tronin, A, and Blasie, JK. "Control of the orientational order and nonlinear optical response of the "push-pull" chromophore RuPZn via specific incorporation into densely packed monolayer ensembles of an amphiphilic 4-helix bundle peptide: second harmonic generation at high chromophore densities." J Am Chem Soc 132.28 (July 21, 2010): 9693-9700.
PMID
20578696
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
28
Publish Date
2010
Start Page
9693
End Page
9700
DOI
10.1021/ja1010724

Optimizing single-molecule conductivity of conjugated organic oligomers with carbodithioate linkers.

In molecular electronics, the linker group, which attaches the functional molecular core to the electrode, plays a crucial role in determining the overall conductivity of the molecular junction. While much focus has been placed on optimizing molecular core conductivity, there have been relatively few attempts at designing optimal linker groups to metallic or semiconducting electrodes. The vast majority of molecular electronic studies use thiol linker groups; work probing alternative amine linker systems has only recently been explored. Here, we probe single-molecule conductances in phenylene-ethynylene molecules terminated with thiol and carbodithioate linkers, experimentally using STM break-junction methods and theoretically using a nonequilibrium Green's function approach. Experimental studies demonstrate that the carbodithioate linker augments electronic coupling to the metal electrode and lowers the effective barrier for charge transport relative to the conventional thiol linker, thus enhancing the conductance of the linker-phenylene-ethynylene-linker unit; these data underscore that phenylene-ethynylene-based structures are more highly conductive than originally appreciated in molecular electronics applications. The theoretical analysis shows that the nature of sulfur hybridization in these species is responsible for the order-of-magnitude increased conductance in carbodithioate-terminated systems relative to identical conjugated structures that feature classic thiol linkers, independent of the mechanism of charge transport. Interestingly, in these systems, the tunneling current is not dominated by the frontier molecular orbitals. While barriers k(B)T to produce the low beta values seen in our experiments. Taken together, these experimental and theoretical studies indicate a promising role for carbodithioate-based connectivity in molecular-scale electronics applications involving metallic and semiconducting electrodes.

Authors
Xing, Y; Park, T-H; Venkatramani, R; Keinan, S; Beratan, DN; Therien, MJ; Borguet, E
MLA Citation
Xing, Y, Park, T-H, Venkatramani, R, Keinan, S, Beratan, DN, Therien, MJ, and Borguet, E. "Optimizing single-molecule conductivity of conjugated organic oligomers with carbodithioate linkers." J Am Chem Soc 132.23 (June 16, 2010): 7946-7956.
Website
http://hdl.handle.net/10161/4052
PMID
20433175
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
23
Publish Date
2010
Start Page
7946
End Page
7956
DOI
10.1021/ja909559m

Computational design and elaboration of a de novo heterotetrameric alpha-helical protein that selectively binds an emissive abiological (porphinato)zinc chromophore.

The first example of a computationally de novo designed protein that binds an emissive abiological chromophore is presented, in which a sophisticated level of cofactor discrimination is pre-engineered. This heterotetrameric, C(2)-symmetric bundle, A(His):B(Thr), uniquely binds (5,15-di[(4-carboxymethyleneoxy)phenyl]porphinato)zinc [(DPP)Zn] via histidine coordination and complementary noncovalent interactions. The A(2)B(2) heterotetrameric protein reflects ligand-directed elements of both positive and negative design, including hydrogen bonds to second-shell ligands. Experimental support for the appropriate formulation of [(DPP)Zn:A(His):B(Thr)](2) is provided by UV/visible and circular dichroism spectroscopies, size exclusion chromatography, and analytical ultracentrifugation. Time-resolved transient absorption and fluorescence spectroscopic data reveal classic excited-state singlet and triplet PZn photophysics for the A(His):B(Thr):(DPP)Zn protein (k(fluorescence) = 4 x 10(8) s(-1); tau(triplet) = 5 ms). The A(2)B(2) apoprotein has immeasurably low binding affinities for related [porphinato]metal chromophores that include a (DPP)Fe(III) cofactor and the zinc metal ion hemin derivative [(PPIX)Zn], underscoring the exquisite active-site binding discrimination realized in this computationally designed protein. Importantly, elements of design in the A(His):B(Thr) protein ensure that interactions within the tetra-alpha-helical bundle are such that only the heterotetramer is stable in solution; corresponding homomeric bundles present unfavorable ligand-binding environments and thus preclude protein structural rearrangements that could lead to binding of (porphinato)iron cofactors.

Authors
Fry, HC; Lehmann, A; Saven, JG; DeGrado, WF; Therien, MJ
MLA Citation
Fry, HC, Lehmann, A, Saven, JG, DeGrado, WF, and Therien, MJ. "Computational design and elaboration of a de novo heterotetrameric alpha-helical protein that selectively binds an emissive abiological (porphinato)zinc chromophore." J Am Chem Soc 132.11 (March 24, 2010): 3997-4005.
Website
http://hdl.handle.net/10161/4048
PMID
20192195
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
132
Issue
11
Publish Date
2010
Start Page
3997
End Page
4005
DOI
10.1021/ja907407m

Plasmon enhanced photoconduction in porphyrin-gold nanoparticle assemblies for photovoltaic applications

Authors
Nanayakkara, SU; Banerjee, P; Conklin, D; Park, T-H; Stecher, JT; Therien, MJ; Bonnell, DA
MLA Citation
Nanayakkara, SU, Banerjee, P, Conklin, D, Park, T-H, Stecher, JT, Therien, MJ, and Bonnell, DA. "Plasmon enhanced photoconduction in porphyrin-gold nanoparticle assemblies for photovoltaic applications." March 21, 2010.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
239
Publish Date
2010

Plasmon-induced electrical conduction in molecular devices.

Metal nanoparticles (NPs) respond to electromagnetic waves by creating surface plasmons (SPs), which are localized, collective oscillations of conduction electrons on the NP surface. When interparticle distances are small, SPs generated in neighboring NPs can couple to one another, creating intense fields. The coupled particles can then act as optical antennae capturing and refocusing light between them. Furthermore, a molecule linking such NPs can be affected by these interactions as well. Here, we show that by using an appropriate, highly conjugated multiporphyrin chromophoric wire to couple gold NP arrays, plasmons can be used to control electrical properties. In particular, we demonstrate that the magnitude of the observed photoconductivity of covalently interconnected plasmon-coupled NPs can be tuned independently of the optical characteristics of the molecule-a result that has significant implications for future nanoscale optoelectronic devices.

Authors
Banerjee, P; Conklin, D; Nanayakkara, S; Park, T-H; Therien, MJ; Bonnell, DA
MLA Citation
Banerjee, P, Conklin, D, Nanayakkara, S, Park, T-H, Therien, MJ, and Bonnell, DA. "Plasmon-induced electrical conduction in molecular devices." ACS Nano 4.2 (February 23, 2010): 1019-1025.
Website
http://hdl.handle.net/10161/4102
PMID
20095631
Source
pubmed
Published In
ACS Nano
Volume
4
Issue
2
Publish Date
2010
Start Page
1019
End Page
1025
DOI
10.1021/nn901148m

Predicting the frequency dispersion of electronic hyperpolarizabilities on the basis of absorption data and thomas-kuhn sum rules

Successfully predicting the frequency dispersion of electronic hyperpolarizabilities is an unresolved challenge in materials science and electronic structure theory. We show that the generalized Thomas-Kuhn sum rules, combined with linear absorption data and measured hyperpolarizability at one or two frequencies, may be used to predict the entire frequency-dependent electronic hyperpolarizability spectrum. This treatment includes two- and three-level contributions that arise from the lowest two or three excited electronic state manifolds, enabling us to describe the unusual observed frequency dispersion of the dynamic hyperpolarizability in high oscillator strength M-PZn chromophores, where (porphinato)zinc(II) (PZn) and metal(II)polypyridyl (M) units are connected via an ethyne unit that aligns the high oscillator strength transition dipoles of these components in a head-to-tail arrangement. We show that some of these structures can possess very similar linear absorption spectra yet manifest dramatically different frequency dependent hyperpolarizabilities, because of three-level contributions that result from excited state-to excited state transition dipoles among charge polarized states. Importantly, this approach provides a quantitative scheme to use linear optical absorption spectra and very limited individual hyperpolarizability measurements to predict the entire frequency-dependent nonlinear optical response. Copyright © 2010 American Chemical Society.

Authors
Hu, X; Xiao, D; Keinan, S; Asselberghs, I; Therien, MJ; Clays, K; Yang, W; Beratan, DN
MLA Citation
Hu, X, Xiao, D, Keinan, S, Asselberghs, I, Therien, MJ, Clays, K, Yang, W, and Beratan, DN. "Predicting the frequency dispersion of electronic hyperpolarizabilities on the basis of absorption data and thomas-kuhn sum rules." Journal of Physical Chemistry C 114.5 (2010): 2349-2359.
Website
http://hdl.handle.net/10161/4078
Source
scival
Published In
The Journal of Physical Chemistry C
Volume
114
Issue
5
Publish Date
2010
Start Page
2349
End Page
2359
DOI
10.1021/jp911556x

Analysis of the unusual wavelength dependence of the first hyperpolarizability of porphyrin derivatives

Successfully predicting the frequency dispersion of electronic hyperpolarizabilities is an unresolved challenge in materials science and electronic structure theory. It has been shown1 that the generalized Thomas-Kuhn sum rules combined with linear absorption data and measured hyperpolarizabilities at one or two frequencies, may be used to predict the entire frequency-dependent electronic hyperpolarizability spectrum. This treatment includes two- and three-level contributions that arise from the lowest two or three excited state manifolds, enabling us to describe the unusual observed frequency dispersion of the dynamic hyperpolarizability in high oscillator strength M-PZn chromophores, where (porphinato)zinc(II) (PZn) and metal(II)polypyridyl (M) units are connected via an ethyne unit that aligns the high oscillator strength transition dipoles of these components in a head-to-tail arrangement. Importantly, this approach provides a quantitative scheme to use linear optical absorption spectra and very few individual hyperpolarizability values to predict the entire frequency-dependent nonlinear optical response. In addition we provide here experimental dynamic hyperpolarizability values determined by hyper-Rayleigh scattering that underscore the validity of our approach. © 2010 SPIE.

Authors
Mey, KD; Clays, K; Therien, MJ; Beratan, DN; Asselberghs, I
MLA Citation
Mey, KD, Clays, K, Therien, MJ, Beratan, DN, and Asselberghs, I. "Analysis of the unusual wavelength dependence of the first hyperpolarizability of porphyrin derivatives." Proceedings of SPIE - The International Society for Optical Engineering 7774 (2010).
Source
scival
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
7774
Publish Date
2010
DOI
10.1117/12.859819

Single-chain, helical wrapping of individualized, single-walled carbon nanotubes by semiconducting polymers in both aqueous and nonaqueous solvents

Authors
Deria, P; Kang, YK; Lee, O-S; Sinks, LE; Kim, SH; Park, T-H; Bonnell, DA; Saven, JG; Therien, MJ
MLA Citation
Deria, P, Kang, YK, Lee, O-S, Sinks, LE, Kim, SH, Park, T-H, Bonnell, DA, Saven, JG, and Therien, MJ. "Single-chain, helical wrapping of individualized, single-walled carbon nanotubes by semiconducting polymers in both aqueous and nonaqueous solvents." August 16, 2009.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
238
Publish Date
2009

In vivo dendritic cell tracking using fluorescence lifetime imaging and near-infrared-emissive polymersomes.

PURPOSE: Noninvasive in vivo cell-tracking techniques are necessary to advance the field of cellular-based therapeutics as well as to elucidate mechanisms governing in vivo cell biology. Fluorescence is commonly used for in vitro and postmortem biomedical studies but has been limited by autofluorescence at the whole-animal level. PROCEDURES: In this report, we demonstrate the ability of in vivo fluorescent lifetime imaging to remove autofluorescence and thereby enable in vivo dendritic cell tracking in naïve mice. Specifically, we track mature dendritic cells (DCs) labeled internally with near-infrared-emissive polymersomes (NIR-DCs). RESULTS: We establish the ability to detect labeled cells in vivo and image NIR-DC trafficking after both intravenous and subcutaneous delivery. In addition, we demonstrate the longitudinal capacity of this method by characterizing NIR-DC migration kinetics in the popliteal lymph node. CONCLUSIONS: This work provides a tool to evaluate dendritic-cell-based immunotherapy and generates novel opportunities for in vivo fluorescence imaging.

Authors
Christian, NA; Benencia, F; Milone, MC; Li, G; Frail, PR; Therien, MJ; Coukos, G; Hammer, DA
MLA Citation
Christian, NA, Benencia, F, Milone, MC, Li, G, Frail, PR, Therien, MJ, Coukos, G, and Hammer, DA. "In vivo dendritic cell tracking using fluorescence lifetime imaging and near-infrared-emissive polymersomes." Mol Imaging Biol 11.3 (May 2009): 167-177.
PMID
19194761
Source
pubmed
Published In
Molecular Imaging and Biology
Volume
11
Issue
3
Publish Date
2009
Start Page
167
End Page
177
DOI
10.1007/s11307-008-0184-x

Physical chemistry: How to improve your image.

Authors
Therien, MJ
MLA Citation
Therien, MJ. "Physical chemistry: How to improve your image." Nature 458.7239 (April 9, 2009): 716-717.
PMID
19360076
Source
pubmed
Published In
Nature
Volume
458
Issue
7239
Publish Date
2009
Start Page
716
End Page
717
DOI
10.1038/458716b

One- and two-photon absorption of highly conjugated multiporphyrin systems in the two-photon Soret transition region.

This study presents a detailed investigation of near-infrared one- and two-photon absorption (TPA) in a series of highly conjugated (porphinato)zinc(II) compounds. The chromophores interrogated include meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZn(n) species), (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes, PZn(n) structures featuring terminal electron-releasing and -withdrawing substituents, related conjugated arrays in which electron-rich and -poor PZn units alternate, and benchmark PZn monomers. Broadband TPA cross-section measurements were performed ratiometrically using fluorescein as a reference. Superficially, the measurements indicate very large TPA cross-sections (up to approximately 10(4) GM; 1 GM = 1x10(-50) cm(4) s photon(-1)) in the two-photon Soret (or B-band) resonance region. However, a more careful analysis of fluorescence as a function of incident photon flux suggests that significant one-photon absorption is present in the same spectral region for all compounds in the series. TPA cross-sections are extracted for the first time for some of these compounds using a model that includes both one-photon absorption and TPA contributions. Resultant TPA cross-sections are approximately 10 GM. The findings suggest that large TPA cross-sections reported in the Soret resonance region of similar compounds might contain significant contributions from one-photon absorption processes.

Authors
Fisher, JAN; Susumu, K; Therien, MJ; Yodh, AG
MLA Citation
Fisher, JAN, Susumu, K, Therien, MJ, and Yodh, AG. "One- and two-photon absorption of highly conjugated multiporphyrin systems in the two-photon Soret transition region." J Chem Phys 130.13 (April 7, 2009): 134506-.
PMID
19355750
Source
pubmed
Published In
Journal of Chemical Physics
Volume
130
Issue
13
Publish Date
2009
Start Page
134506
DOI
10.1063/1.3089795

Helical wrapping of single-walled carbon nanotubes by water soluble poly(p-phenyleneethynylene).

Amphiphilic, linear conjugated poly[p-{2,5-bis(3-propoxysulfonicacidsodiumsalt)}phenylene]ethynylene (PPES) efficiently disperses single-walled carbon nanotubes (SWNTs) under ultrasonication conditions into the aqueous phase. Vis-NIR absorption spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) demonstrate that these solubilized SWNTs are highly individualized. AFM and TEM data reveal that the interaction of PPES with SWNTs gives rise to a self-assembled superstructure in which a polymer monolayer helically wraps the nanotube surface; the observed PPES pitch length (13 +/- 2 nm) confirms structural predictions made via molecular dynamics simulations. This work underscores design elements important for engineering well-defined nanotube-semiconducting polymer hybrid structures.

Authors
Kang, YK; Lee, O-S; Deria, P; Kim, SH; Park, T-H; Bonnell, DA; Saven, JG; Therien, MJ
MLA Citation
Kang, YK, Lee, O-S, Deria, P, Kim, SH, Park, T-H, Bonnell, DA, Saven, JG, and Therien, MJ. "Helical wrapping of single-walled carbon nanotubes by water soluble poly(p-phenyleneethynylene)." Nano Lett 9.4 (April 2009): 1414-1418.
PMID
19281229
Source
pubmed
Published In
Nano Letters
Volume
9
Issue
4
Publish Date
2009
Start Page
1414
End Page
1418
DOI
10.1021/nl8032334

Photoinitiated destruction of composite porphyrin-protein polymersomes.

Bilayer vesicles assembled from amphiphilic diblock copolymers (polymersomes) adopt asymmetric structures when loaded with moderate concentrations (>or=1.5 mg/mL) of horse spleen ferritin (HSF) or its iron-free variant (HSAF). Incorporation of both ferritin and a zinc porphyrin dimer (PZn(2)) generates photoresponsive vesicles: irradiation with focused light of near-UV to near-IR wavelengths induces polymersome deformation and destruction on the minute time scale. To investigate this phenomenon, polymersomes were loaded with dye-labeled ferritin and PZn(2). Confocal microscopy identified BODIPY-FL-labeled ferritin at the membrane, whereas Cy3-labeled ferritin was found both at the membrane and throughout the aqueous core. Fluorescence recovery after photobleaching (FRAP) experiments confirmed that Cy3- and BODIPY-FL-labeled ferritin and PZn(2) exhibited slow diffusion at the membrane, consistent with membrane association. Furthermore, micropipette aspiration experiments revealed increased elastic moduli and altered bending rigidity in vesicles incorporating HSAF. Finally, a small molecule (biocytin) was encapsulated within the ferritin-PZn(2) vesicles and released upon exposure to light. These data indicate synergy between ferritin, whose membrane association lowers the barrier to deformation, and PZn(2), which embeds in the membrane, harvests light energy and produces local heating that may lead to membrane budding. This appears to be a general protein-polymer membrane phenomenon, as replacement of ferritin with bovine serum albumin or equine skeletal myoglobin resulted in vesicles with similar asymmetric morphology and photosensitivity.

Authors
Robbins, GP; Jimbo, M; Swift, J; Therien, MJ; Hammer, DA; Dmochowski, IJ
MLA Citation
Robbins, GP, Jimbo, M, Swift, J, Therien, MJ, Hammer, DA, and Dmochowski, IJ. "Photoinitiated destruction of composite porphyrin-protein polymersomes." J Am Chem Soc 131.11 (March 25, 2009): 3872-3874.
PMID
19249827
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
131
Issue
11
Publish Date
2009
Start Page
3872
End Page
3874
DOI
10.1021/ja808586q

Incorporating abiological function in de novo designed proteins

Authors
Fry, HC; Lehmann, A; Tronin, A; Krishnan, V; Blasie, JK; Saven, JG; DeGrado, WF; Therien, MJ
MLA Citation
Fry, HC, Lehmann, A, Tronin, A, Krishnan, V, Blasie, JK, Saven, JG, DeGrado, WF, and Therien, MJ. "Incorporating abiological function in de novo designed proteins." March 22, 2009.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
237
Publish Date
2009

Light induced destruction of polymersome/porphyrin/ferritin composite membranes

Authors
Hammer, DA; Robbins, G; Jimbo, M; Swift, J; Therien, MJ; Dmochowski, IJ
MLA Citation
Hammer, DA, Robbins, G, Jimbo, M, Swift, J, Therien, MJ, and Dmochowski, IJ. "Light induced destruction of polymersome/porphyrin/ferritin composite membranes." March 22, 2009.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
237
Publish Date
2009

In vivo fluorescence imaging: a personal perspective.

In vivo fluorescence imaging with near-infrared (NIR) light holds enormous potential for a wide variety of molecular diagnostic and therapeutic applications. Because of its quantitative sensitivity, inherent biological safety, and relative ease of use (i.e., with respect to cost, time, mobility, and its familiarity to a diverse population of investigators), fluorescence-based imaging techniques are being increasingly utilized in small-animal research. Moreover, there is substantial interest in the translation of novel optical techniques into the clinic, where they will prospectively aid in noninvasive and quantitative screening, disease diagnosis, and post-treatment monitoring of patients. Effective deep-tissue fluorescence imaging requires the application of exogenous NIR-emissive contrast agents. Currently, available probes fall into two major categories: organic and inorganic NIR fluorophores (NIRFs). In the studies reviewed herein, we utilized polymersomes (50 nm to 50 microm diameter polymer vesicles) for the incorporation and delivery of large numbers of highly emissive oligo (porphyrin)-based, organic NIRFs.

Authors
Ghoroghchian, PP; Therien, MJ; Hammer, DA
MLA Citation
Ghoroghchian, PP, Therien, MJ, and Hammer, DA. "In vivo fluorescence imaging: a personal perspective." Wiley Interdiscip Rev Nanomed Nanobiotechnol 1.2 (March 2009): 156-167. (Review)
PMID
20049787
Source
pubmed
Published In
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology
Volume
1
Issue
2
Publish Date
2009
Start Page
156
End Page
167
DOI
10.1002/wnan.7

Composite electronic materials for supercapacitor applications

The polyanionic, poly(aryleneethynylene) polymer PNES that helically wraps single-walled carbon nanotubes (SWNTs) was used in a variety of novel electrically active composites, combined with the electroactive polymer poly(3,4-propylenedioxythiophene) PProDOT, to function as supercapacitor charge storage media. PNES provides solubility and dispersion characteristics for SWNTs in water and in organic solvents like methanol (MeOH). PNES/SWNT samples were prepared by drop casting PNES/SWNT/MeOH suspensions on Pt button electrodes; high stability PProDOT/PNES/SWNT composites were then prepared by electrochemical polymerization in ionic liquid/propylene carbonate electrolyte solution. These composites enhanced key redox capacitors rubrics compared to those of PProDOT-based terminals. The PNES-wrapped SWNTs were characterized by transmission electron microscopy and Vis-NIR absorption spectroscopy. PProDOT- and PProDOT/PNES/SWNT-based devices were interrogated by cyclic voltammetry (CV) to different cell voltages. Electronic transport properties of the PNES/SWNT composite samples were measured from 2K to room temperature. © The Electrochemical Society.

Authors
Rosario-Canales, MR; Deria, P; Gopu, P; Therien, MJ; Santiago-Avilés, JJ
MLA Citation
Rosario-Canales, MR, Deria, P, Gopu, P, Therien, MJ, and Santiago-Avilés, JJ. "Composite electronic materials for supercapacitor applications." ECS Transactions 23.1 (2009): 3-10.
Source
scival
Published In
ECS Transactions
Volume
23
Issue
1
Publish Date
2009
Start Page
3
End Page
10
DOI
10.1149/1.3183695

Probing polarization and dielectric function of molecules with higher order harmonics in scattering-near-field scanning optical microscopy

The idealized system of an atomically flat metallic surface [highly oriented pyrolytic graphite (HOPG)] and an organic monolayer (porphyrin) was used to determine whether the dielectric function and associated properties of thin films can be accessed with scanning-near-field scanning optical microscopy (s-NSOM). Here, we demonstrate the use of harmonics up to fourth order and the polarization dependence of incident light to probe dielectric properties on idealized samples of monolayers of organic molecules on atomically smooth substrates. An analytical treatment of light/sample interaction using the s-NSOM tip was developed in order to quantify the dielectric properties. The theoretical analysis and numerical modeling, as well as experimental data, demonstrate that higher order harmonic scattering can be used to extract the dielectric properties of materials with tens of nanometer spatial resolution. To date, the third harmonic provides the best lateral resolution (∼50 nm) and dielectric constant contrast for a porphyrin film on HOPG. © 2009 American Institute of Physics.

Authors
Nikiforov, MP; Kehr, SC; Park, T-H; Milde, P; Zerweck, U; Loppacher, C; Eng, LM; Therien, MJ; Engheta, N; Bonnell, D
MLA Citation
Nikiforov, MP, Kehr, SC, Park, T-H, Milde, P, Zerweck, U, Loppacher, C, Eng, LM, Therien, MJ, Engheta, N, and Bonnell, D. "Probing polarization and dielectric function of molecules with higher order harmonics in scattering-near-field scanning optical microscopy." Journal of Applied Physics 106.11 (2009).
Website
http://hdl.handle.net/10161/3353
Source
scival
Published In
Journal of Applied Physics
Volume
106
Issue
11
Publish Date
2009
DOI
10.1063/1.3245392

Portable UV-visible spectrometer for measuring absorbance and dichroism of Langmuir monolayers at air-water interfaces

An UV-visible spectrometer for measuring absorbance and dichroism of Langmuir monolayers under in situ conditions is described. The spectrometer utilizes a stand-alone multipass sensor, which is placed in a Langmuir trough and coupled with light source and spectrometer head via fiber optics. Implementation of the multipass scheme in the absorbance sensor makes it possible to obtain reliable quantitative spectroscopic data of the Langmuir monolayers with absorbance as low as 1 mOD. Such high sensitivity makes the developed sensor very useful for UV-visible spectral studies of a wide variety of chromophores. The new technique was applied to several model systems: fatty acid monolayers containing amphiphilic dyes DiI or BODIPY and also a monolayer of a synthetic amphiphilic porphyrin-binding peptide BBC16. Implementation of UV-visible absorbance spectroscopy measurements in situ together with x-ray scattering technique was used to confirm the bound state of the chromophore, and determine the exact position of the latter in the peptide matrix. Fiber optics design of the spectrometer provides portability and compatibility with other experimental techniques making it possible to study samples with a geometry unsuitable for conventional spectroscopic measurements and located in experimental environments with spatial limitations, such as synchrotron x-ray scattering stations. © 2009 American Institute of Physics.

Authors
Tronin, A; Strzalka, J; Krishnan, V; Kuzmenko, I; Fry, HC; Therien, M; Blasie, JK
MLA Citation
Tronin, A, Strzalka, J, Krishnan, V, Kuzmenko, I, Fry, HC, Therien, M, and Blasie, JK. "Portable UV-visible spectrometer for measuring absorbance and dichroism of Langmuir monolayers at air-water interfaces." Review of Scientific Instruments 80.3 (2009).
PMID
19334902
Source
scival
Published In
Review of Scientific Instruments
Volume
80
Issue
3
Publish Date
2009
DOI
10.1063/1.3089807

In vivo fluorescence imaging: a personal perspective

Authors
Ghoroghchian, PP; Therien, MJ; Hammer, DA
MLA Citation
Ghoroghchian, PP, Therien, MJ, and Hammer, DA. "In vivo fluorescence imaging: a personal perspective." WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 1.2 (2009): 156-167.
Source
wos-lite
Published In
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology
Volume
1
Issue
2
Publish Date
2009
Start Page
156
End Page
167
DOI
10.1002/wnan.007

Molecular design of porphyrin-based nonlinear optical materials.

Nonlinear optical chromophores containing (porphyrinato)Zn(II), proquinoid, and (terpyridyl)metal(II) building blocks were optimized in a library containing approximately 10(6) structures using the linear combination of atomic potentials (LCAP) methodology. We report here the library design and molecular property optimizations. Two basic structural types of large beta(0) chromophores were examined: linear and T-shaped motifs. These T-shaped geometries suggest a promising NLO chromophoric architecture for experimental investigation and further support the value of performing LCAP searches in large chemical spaces.

Authors
Keinan, S; Therien, MJ; Beratan, DN; Yang, W
MLA Citation
Keinan, S, Therien, MJ, Beratan, DN, and Yang, W. "Molecular design of porphyrin-based nonlinear optical materials." J Phys Chem A 112.47 (November 27, 2008): 12203-12207.
PMID
18973325
Source
pubmed
Published In
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
Volume
112
Issue
47
Publish Date
2008
Start Page
12203
End Page
12207
DOI
10.1021/jp806351d

Using alpha-helical coiled-coils to design nanostructured metalloporphyrin arrays.

We have developed a computational design strategy based on the alpha-helical coiled-coil to generate modular peptide motifs capable of assembling into metalloporphyrin arrays of varying lengths. The current study highlights the extension of a two-metalloporphyrin array to a four-metalloporphyrin array through the incorporation of a coiled-coil repeat unit. Molecular dynamics simulations demonstrate that the initial design evolves rapidly to a stable structure with a small rmsd compared to the original model. Biophysical characterization reveals elongated proteins of the desired length, correct cofactor stoichiometry, and cofactor specificity. The successful extension of the two-porphyrin array demonstrates how this methodology serves as a foundation to create linear assemblies of organized electrically and optically responsive cofactors.

Authors
McAllister, KA; Zou, H; Cochran, FV; Bender, GM; Senes, A; Fry, HC; Nanda, V; Keenan, PA; Lear, JD; Saven, JG; Therien, MJ; Blasie, JK; DeGrado, WF
MLA Citation
McAllister, KA, Zou, H, Cochran, FV, Bender, GM, Senes, A, Fry, HC, Nanda, V, Keenan, PA, Lear, JD, Saven, JG, Therien, MJ, Blasie, JK, and DeGrado, WF. "Using alpha-helical coiled-coils to design nanostructured metalloporphyrin arrays." J Am Chem Soc 130.36 (September 10, 2008): 11921-11927.
PMID
18710226
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
130
Issue
36
Publish Date
2008
Start Page
11921
End Page
11927
DOI
10.1021/ja800697g

Polymersomes: a new multi-functional tool for cancer diagnosis and therapy.

Nanoparticles are being developed as delivery vehicles for therapeutic pharmaceuticals and contrast imaging agents. Polymersomes (mesoscopic polymer vesicles) possess a number of attractive biomaterial properties that make them ideal for these applications. Synthetic control over block copolymer chemistry enables tunable design of polymersome material properties. The polymersome architecture, with its large hydrophilic reservoir and its thick hydrophobic lamellar membrane, provides significant storage capacity for both water soluble and insoluble substances (such as drugs and imaging probes). Further, the brush-like architecture of the polymersome outer shell can potentially increase biocompatibility and blood circulation times. A further recent advance is the development of multi-functional polymersomes that carry pharmaceuticals and imaging agents simultaneously. The ability to conjugate biologically active ligands to the brush surface provides a further means for targeted therapy and imaging. Hence, polymersomes hold enormous potential as nanostructured biomaterials for future in vivo drug delivery and diagnostic imaging applications.

Authors
Levine, DH; Ghoroghchian, PP; Freudenberg, J; Zhang, G; Therien, MJ; Greene, MI; Hammer, DA; Murali, R
MLA Citation
Levine, DH, Ghoroghchian, PP, Freudenberg, J, Zhang, G, Therien, MJ, Greene, MI, Hammer, DA, and Murali, R. "Polymersomes: a new multi-functional tool for cancer diagnosis and therapy." Methods 46.1 (September 2008): 25-32. (Review)
PMID
18572025
Source
pubmed
Published In
Methods
Volume
46
Issue
1
Publish Date
2008
Start Page
25
End Page
32
DOI
10.1016/j.ymeth.2008.05.006

POLY 512-Charge transport properties of solution processable (porphinato)zinc(II) ethynylenes

Authors
Frail, PR; Kikkawa, JM; Angiolillo, PJ; Therien, MJ; Kagan, CR
MLA Citation
Frail, PR, Kikkawa, JM, Angiolillo, PJ, Therien, MJ, and Kagan, CR. "POLY 512-Charge transport properties of solution processable (porphinato)zinc(II) ethynylenes." August 17, 2008.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
236
Publish Date
2008

Ultrafast excited-state dynamics of nanoscale near-infrared emissive polymersomes.

Formed through cooperative self-assembly of amphiphilic diblock copolymers and electronically conjugated porphyrinic near-infrared (NIR) fluorophores (NIRFs), NIR-emissive polymersomes (50 nm to 50 microm diameter polymer vesicles) define a family of organic-based, soft-matter structures that are ideally suited for deep-tissue optical imaging and sensitive diagnostic applications. Here, we describe magic angle and polarized pump-probe spectroscopic experiments that: (i) probe polymersome structure and NIRF organization and (ii) connect emitter structural properties and NIRF loading with vesicle emissive output at the nanoscale. Within polymersome membrane environments, long polymer chains constrain ethyne-bridged oligo(porphinato)zinc(II) based supermolecular fluorophore (PZn n ) conformeric populations and disperse these PZn n species within the hydrophobic bilayer. Ultrafast excited-state transient absorption and anisotropy dynamical studies of NIR-emissive polymersomes, in which the PZn n fluorophore loading per nanoscale vesicle is varied between 0.1-10 mol %, enable the exploration of concentration-dependent mechanisms for nonradiative excited-state decay. These experiments correlate fluorophore structure with its gross spatial arrangement within specific nanodomains of these nanoparticles and reveal how compartmentalization of fluorophores within reduced effective dispersion volumes impacts bulk photophysical properties. As these factors play key roles in determining the energy transfer dynamics between dispersed fluorophores, this work underscores that strategies that modulate fluorophore and polymer structure to optimize dispersion volume in bilayered nanoscale vesicular environments will further enhance the emissive properties of these sensitive nanoscale probes.

Authors
Duncan, TV; Ghoroghchian, PP; Rubtsov, IV; Hammer, DA; Therien, MJ
MLA Citation
Duncan, TV, Ghoroghchian, PP, Rubtsov, IV, Hammer, DA, and Therien, MJ. "Ultrafast excited-state dynamics of nanoscale near-infrared emissive polymersomes." J Am Chem Soc 130.30 (July 30, 2008): 9773-9784.
PMID
18611010
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
130
Issue
30
Publish Date
2008
Start Page
9773
End Page
9784
DOI
10.1021/ja711497w

INOR 570-Coupled-oscillator photophysics and the elaboration of chromophores with exceptional molecular hyperpolarizabilities and 2-photon absorptive cross-sections

Authors
Duncan, TV; Ishizuka, T; Sinks, LE; Nayak, A; Song, K; Hung, ST; Keinan, S; Yang, W; Beratan, DN; Clays, K; Therien, MJ
MLA Citation
Duncan, TV, Ishizuka, T, Sinks, LE, Nayak, A, Song, K, Hung, ST, Keinan, S, Yang, W, Beratan, DN, Clays, K, and Therien, MJ. "INOR 570-Coupled-oscillator photophysics and the elaboration of chromophores with exceptional molecular hyperpolarizabilities and 2-photon absorptive cross-sections." April 6, 2008.
Source
wos-lite
Published In
ACS National Meeting Book of Abstracts
Volume
235
Publish Date
2008

Synthesis of water-soluble poly(p-phenyleneethynylene) in neat water under aerobic conditions via Suzuki-Miyaura polycondensation using a diborylethyne synthon.

We report the synthesis, structure, and characterization of a novel ethyne synthon, 1,2-bis(4',4',5',5'-tetramethyl[1',3',2']dioxaborolan-2'-yl)ethyne (B2C2). We demonstrate the utility of B2C2 in the Suzuki-Miyaura polycondensation reaction, synthesizing a water-soluble poly(p-phenyleneethynylene) from [2,5-diiodo-1,4-bis(3-propoxy-sulfonicacid)benzene] sodium salt in neat water under an aerobic atmosphere.

Authors
Kang, YK; Deria, P; Carroll, PJ; Therien, MJ
MLA Citation
Kang, YK, Deria, P, Carroll, PJ, and Therien, MJ. "Synthesis of water-soluble poly(p-phenyleneethynylene) in neat water under aerobic conditions via Suzuki-Miyaura polycondensation using a diborylethyne synthon." Org Lett 10.7 (April 3, 2008): 1341-1344.
PMID
18335946
Source
pubmed
Published In
Organic Letters
Volume
10
Issue
7
Publish Date
2008
Start Page
1341
End Page
1344
DOI
10.1021/ol702758f

Structure and dynamics of an extended conjugated NLO chromophore within an amphiphilic 4-helix bundle peptide by molecular dynamics simulation.

Incorporation of extended conjugated chromophores into amphiphilic 4-helix bundle peptides has been shown experimentally to be an effective means to orient the chromphores vectorially in 2-D ensembles with high in-plane density. The designed microscopic hyperpolarizabilty of the chromophore is preserved in the macroscopic NLO response of the ensemble. We show via molecular dynamics simulation that the designed coiled-coil structure of the bundle controls the conformation and dynamics of the chromophore that are critical to optimizing its hyperpolarizability.

Authors
Zou, H; Therien, MJ; Blasie, JK
MLA Citation
Zou, H, Therien, MJ, and Blasie, JK. "Structure and dynamics of an extended conjugated NLO chromophore within an amphiphilic 4-helix bundle peptide by molecular dynamics simulation." J Phys Chem B 112.5 (February 7, 2008): 1350-1357.
PMID
18189381
Source
pubmed
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
112
Issue
5
Publish Date
2008
Start Page
1350
End Page
1357
DOI
10.1021/jp076643j

The effect of molecular orientation on the potential of porphyrin-metal contacts.

The effect of molecular orientation at metal contacts on interface properties was determined by examining the local work function of porphyrin on atomically smooth graphite. The orientation was varied by self-assembly from the vapor phase, and the local potential was quantified by Kelvin force microscopy (scanning surface potential microscopy). When the porphyrin ring is oriented parallel to the substrate, the surface work function is 50 mV less than that of the highly ordered pyrolytic graphite; in contrast, when the porphyrin molecular plane is oriented perpendicular to the substrate, the surface work function is unchanged. The orientation dependence of the surface work function is determined by the geometric relationships between the delocalized charge densities in the molecule and substrate and possible interface bonding. The differences in interface properties with molecular configuration have important design implications to molecular electronic and organic electronic devices.

Authors
Nikiforov, MP; Zerweck, U; Milde, P; Loppacher, C; Park, T-H; Uyeda, HT; Therien, MJ; Eng, L; Bonnell, D
MLA Citation
Nikiforov, MP, Zerweck, U, Milde, P, Loppacher, C, Park, T-H, Uyeda, HT, Therien, MJ, Eng, L, and Bonnell, D. "The effect of molecular orientation on the potential of porphyrin-metal contacts." Nano Lett 8.1 (January 2008): 110-113.
PMID
18095730
Source
pubmed
Published In
Nano Letters
Volume
8
Issue
1
Publish Date
2008
Start Page
110
End Page
113
DOI
10.1021/nl072175d

Molecular symmetry and solution-phase structure interrogated by hyper-Rayleigh depolarization measurements: elaborating highly hyperpolarizable D2-symmetric chromophores.

Authors
Duncan, TV; Song, K; Hung, S-T; Miloradovic, I; Nayak, A; Persoons, A; Verbiest, T; Therien, MJ; Clays, K
MLA Citation
Duncan, TV, Song, K, Hung, S-T, Miloradovic, I, Nayak, A, Persoons, A, Verbiest, T, Therien, MJ, and Clays, K. "Molecular symmetry and solution-phase structure interrogated by hyper-Rayleigh depolarization measurements: elaborating highly hyperpolarizable D2-symmetric chromophores." Angew Chem Int Ed Engl 47.16 (2008): 2978-2981.
PMID
18338413
Source
pubmed
Published In
Angewandte Chemie International Edition
Volume
47
Issue
16
Publish Date
2008
Start Page
2978
End Page
2981
DOI
10.1002/anie.200703187

Leuko-polymersomes.

Polymersomes are vesicles whose membranes are comprised of self-assembled amphiphilic block co-polymers. Synthetic control of block co-polymer chemistry provides an advantageous diversity of polymersome functions, ranging from tunable materials strength, superior encaspulation of hydrophobic and hydrophilic drugs and optical dyes, and facile functionalization. We have exploited polymersome tunability to make leuko-polymersomes: polymersomes with the adhesive properties of leukocytes. By functionalizing the terminal groups on the outer shell of the vesicle with biotin, we have used modular avidin-biotin chemistry to attach adhesion ligands that mimic the two critical adhesion pathways that leukocytes utilize to achieve adhesion in the fast fluid flow of blood vessels--selectins and integrins. We demonstrate that adhesion is specific and is supported at hydrodynamic flow rates at which leukocytes adhere. We envision the use of such particles for monitoring or treating inflammation, cancer and cardiovascular disease.

Authors
Hammer, DA; Robbins, GP; Haun, JB; Lin, JJ; Qi, W; Smith, LA; Ghoroghchian, PP; Therien, MJ; Bates, FS
MLA Citation
Hammer, DA, Robbins, GP, Haun, JB, Lin, JJ, Qi, W, Smith, LA, Ghoroghchian, PP, Therien, MJ, and Bates, FS. "Leuko-polymersomes." Faraday Discuss 139 (2008): 129-141. (Review)
PMID
19048993
Source
pubmed
Published In
Faraday Discussions
Volume
139
Publish Date
2008
Start Page
129
End Page
141

Orientational Dependence of Cofacial Porphyrin-Quinone Electronic Interactions within the Strong Coupling Regime

Authors
Kang, YK; Zheng, J; Rubtsov, IV; Beratan, DN; Therien, MJ
MLA Citation
Kang, YK, Zheng, J, Rubtsov, IV, Beratan, DN, and Therien, MJ. "Orientational Dependence of Cofacial Porphyrin-Quinone Electronic Interactions within the Strong Coupling Regime (Submitted)." J. Am. Chem. Soc. (2008). (Academic Article)
Source
manual
Published In
J. Am. Chem. Soc.
Publish Date
2008

Influence of Linear and Nonlinear Absorption in the Two-Photon Soret Transition Region of Highly Conjugated Multi-Porphyrin Systems

Authors
Fisher, JAN; Susumu, K; Therien, MJ; Yodh, AG
MLA Citation
Fisher, JAN, Susumu, K, Therien, MJ, and Yodh, AG. "Influence of Linear and Nonlinear Absorption in the Two-Photon Soret Transition Region of Highly Conjugated Multi-Porphyrin Systems (Submitted)." J. Chem. Phys (2008). (Academic Article)
Source
manual
Published In
J. Chem. Phys
Publish Date
2008

Fully bioresorbable polymeric vesicles for therapeutic applications

Authors
Levine, DH; Ghoroghchian, PP; Freudenberg, J; Zhang, G; Li, G; Davis, KP; Bates, F; Therien, MJ; Murali, R; Hammer, DA
MLA Citation
Levine, DH, Ghoroghchian, PP, Freudenberg, J, Zhang, G, Li, G, Davis, KP, Bates, F, Therien, MJ, Murali, R, and Hammer, DA. "Fully bioresorbable polymeric vesicles for therapeutic applications." AIChE Annual Meeting, Conference Proceedings (2008).
Source
scival
Published In
AIChE Annual Meeting, Conference Proceedings
Publish Date
2008

Evaluation of composite electronic materials based upon single-wall carbon nanotubes and highly charged poly(aryleneethynylene)s for supercapacitor applications

Although substantial improvement in capacitance, energy densities, and discharge times has been achieved for redox supercapacitors over the last several years, important challenges remain. These include high series resistance which limits the ability to quickly discharge these devices, excessive heat generation, and the coupled thermoelastic strain field which tends to deform the device materials. High stability composites based upon conjugated polymers that wrap single-wall carbon nanotubes (SWNTs) provide a platform to develop materials that can broadly impact these issues. This work compares the performance of a new class of hybrid materials, polymer-wrapped SWNTs to established electroactive polymer-based anode and cathode material benchmarks of poly(3,4-propylenedioxythiophene) for the construction of supercapacitors. These polymer-wrapped SWNT composites exploit rigid, polyanionic poly(aryleneethynylene)s which provide unusual solubility and dispersion characteristics for carbon nanotubes in several solvents. © The Electrochemical Society.

Authors
Rosario-Canales, MR; Deria, P; Kanga, Y; Therien, MJ; Santiago-Avilé, JJ
MLA Citation
Rosario-Canales, MR, Deria, P, Kanga, Y, Therien, MJ, and Santiago-Avilé, JJ. "Evaluation of composite electronic materials based upon single-wall carbon nanotubes and highly charged poly(aryleneethynylene)s for supercapacitor applications." ECS Transactions 16.1 (2008): 93-101.
Source
scival
Published In
ECS Transactions
Volume
16
Issue
1
Publish Date
2008
Start Page
93
End Page
101
DOI
10.1149/1.298563l

Hyper-Rayleigh scattering for solution phase structure determination

Hyper-Rayleigh scattering (HRS) is the only second-order nonlinear optical (NLO) technique allowed in an isotropic solution. Being an even-order technique, it is sensitive to (non-centro)symmetry. Therefore, HRS is a unique tool to determine solution-phase structure, both in a qualitative and a quantitative way. Examples are presented of the elucidation of the actual D2d octopolar structure of highly symmetric, yet non-centrosymmetric chromophores and of the determination of the value for the opening angle of a chromophore-functionalized alkynyl-calix[4]arene cavity.

Authors
Clays, K; Therien, MJ; Hennrich, G
MLA Citation
Clays, K, Therien, MJ, and Hennrich, G. "Hyper-Rayleigh scattering for solution phase structure determination." Proceedings of SPIE - The International Society for Optical Engineering 7049 (2008).
Source
scival
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
7049
Publish Date
2008
DOI
10.1117/12.793236

Synthesis and self-assembly of biodegradable polyethylene oxide-b-polycaprolactone (PEO-A-PCL) diblock copolymers

A series of amphiphilic poly(ethylene oxide)-b-polycaprolactone (PEO-b-PCL) diblock copolymers had been synthesized by ring-opening or sequential anionic living polymerization. Nuclear Magnetic Resonance (NMR) and gel permeation chromatography (GPC) were used to characterize these copolymers. All copolymers have polydispersity index (PDI) from 1.14 to 1.37 by GPC. Two self-assembly techniques, film rehydration and organic solvent extraction, had been employed to process polymersomes. The perfect nanostructured polymersomes were processed by freeze-thaw-sonication film rehydration technique. The polymersomes with sizes from a hundred nanometer to several microns were obtained from these copolymers. Polymersomes could only be made from the copolymers with PEO blocks (Mn: 2k-3.8k) and fPEO (11.8-18.8%). Film rehydration is a highly favorable self-assembly method for preparing biodegradable nanostructured polymersomes.

Authors
Li, G; Ghoroghchian, P; Qi, W; Christian, N; Frail, PR; Hammer, DA; Therien, MJ
MLA Citation
Li, G, Ghoroghchian, P, Qi, W, Christian, N, Frail, PR, Hammer, DA, and Therien, MJ. "Synthesis and self-assembly of biodegradable polyethylene oxide-b-polycaprolactone (PEO-A-PCL) diblock copolymers." Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, NSTI-Nanotech, Nanotechnology 2008 2 (2008): 661-664.
Source
scival
Published In
Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, NSTI-Nanotech, Nanotechnology 2008
Volume
2
Publish Date
2008
Start Page
661
End Page
664

De novo design of a single-chain diphenylporphyrin metalloprotein.

We describe the computational design of a single-chain four-helix bundle that noncovalently self-assembles with fully synthetic non-natural porphyrin cofactors. With this strategy, both the electronic structure of the cofactor as well as its protein environment may be varied to explore and modulate the functional and photophysical properties of the assembly. Solution characterization (NMR, UV-vis) of the protein showed that it bound with high specificity to the desired cofactors, suggesting that a uniquely structured protein and well-defined site had indeed been created. This provides a genetically expressed single-chain protein scaffold that will allow highly facile, flexible, and asymmetric variations to enable selective incorporation of different cofactors, surface-immobilization, and introduction of spectroscopic probes.

Authors
Bender, GM; Lehmann, A; Zou, H; Cheng, H; Fry, HC; Engel, D; Therien, MJ; Blasie, JK; Roder, H; Saven, JG; DeGrado, WF
MLA Citation
Bender, GM, Lehmann, A, Zou, H, Cheng, H, Fry, HC, Engel, D, Therien, MJ, Blasie, JK, Roder, H, Saven, JG, and DeGrado, WF. "De novo design of a single-chain diphenylporphyrin metalloprotein." J Am Chem Soc 129.35 (September 5, 2007): 10732-10740.
PMID
17691729
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
129
Issue
35
Publish Date
2007
Start Page
10732
End Page
10740
DOI
10.1021/ja071199j

Molecular engineering of intensely near-infrared absorbing excited states in highly conjugated oligo(porphinato)zinc-(polypyridyl)metal(II) supermolecules.

A new series of chromophores, MPZn(n), which combine ethyne-bridged bis(terpyridyl)metal(II)-(porphinato)zinc(II) (MPZ(n)) and oligomeric, ethyne-bridged (porphinato)zinc(II) (PZn(n)) architectures, have been synthesized and characterized, along with a series of derivatives bearing pyrrolidinyl electron-releasing groups on the ancillary terpyridine units (Pyr(m)MPZn(n)). Cyclic voltammetric studies, as well as NMR, electronic absorption, fluorescence, and femtosecond pump-probe transient absorption spectroscopies, have been employed to study the ground- and excited-state properties of these unusual chromophores. All of these species possess intensely absorbing excited states having large spectral bandwidth that penetrate deep in the near-infrared (NIR) energy regime. Electronic structural variation of the molecular framework shows that the excited-state absorption maximum can be extensively modulated [lambdamax(T(1) --> T(n))] (880 nm < lambdamax < 1126 nm), while concomitantly maintaining impressively large T(1) --> T(n) absorption manifold spectral bandwidth (full width at half-maximum, fwhm, approximately 2000-2500 cm(-1)). Furthermore, these studies enable correlation of supermolecular electronic structure with the magnitude of the excited-state lifetime (tau(es)) and demonstrate that this parameter can be modulated over 4 orders of magnitude ( approximately 1 ns < tau(es) < 45 micros). Terpyridyl pyrrolidinyl substituents can be utilized to destabilize terpyridyl ligand pi(*) energy levels and diminish the E1/2 (M3+/2+) value of the bis(terpyridyl)metal(II) center: such perturbations determine the relative energies of the PZn(n)-derived 1pi-pi(*) and bis(terpyridyl)metal(II) charge-transfer states and establish whether the T(1)-state wave functions of MPZn(n) and PyrmMPZn(n) species manifest the extensive electronic delocalization and charge-separated (CS) features characteristic of long-lived triplet states that absorb strongly in the NIR.

Authors
Duncan, TV; Ishizuka, T; Therien, MJ
MLA Citation
Duncan, TV, Ishizuka, T, and Therien, MJ. "Molecular engineering of intensely near-infrared absorbing excited states in highly conjugated oligo(porphinato)zinc-(polypyridyl)metal(II) supermolecules." J Am Chem Soc 129.31 (August 8, 2007): 9691-9703.
PMID
17629267
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
129
Issue
31
Publish Date
2007
Start Page
9691
End Page
9703
DOI
10.1021/ja0707512

Carbodithioate-terminated oligo(phenyleneethynylene)s: synthesis and surface functionalization of gold nanoparticles.

Carbodithioate-terminated bis(phenylene)ethynylenes and oligo(phenyleneethynylene)s have been synthesized from TMSE-protected 4-iododithiobenzoic acid ester (1) and 4-ethynyldithiobenzoic acid ester (3) via Pd-catalyzed cross-coupling reactions. TEM and spectroscopic studies demonstrate that the reaction of 4-(phenylethynyl)dithiobenzoate with alkylamine-protected gold nanoparticles (AuNPs) produces the corresponding organocarbodithioate-functionalized AuNPs.

Authors
Park, T-H; Therien, MJ
MLA Citation
Park, T-H, and Therien, MJ. "Carbodithioate-terminated oligo(phenyleneethynylene)s: synthesis and surface functionalization of gold nanoparticles." Org Lett 9.15 (July 19, 2007): 2779-2782.
PMID
17602486
Source
pubmed
Published In
Organic Letters
Volume
9
Issue
15
Publish Date
2007
Start Page
2779
End Page
2782
DOI
10.1021/ol070789j

Temperature-dependent mechanistic transition for photoinduced electron transfer modulated by excited-state vibrational relaxation dynamics.

The electron transfer (ET) dynamics of an unusually rigid pi-stacked (porphinato)zinc(II)-spacer-quinone (PZn-Q) system, [5-[8'-(4' '-[8' ''-(2' '' ',5' '' '-benzoquinonyl)-1' ''-naphthyl]-1' '-phenyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (2a-Zn), in which sub-van der Waals interplanar distances separate juxtaposed porphyryl, aromatic bridge, and quinonyl components of this assembly, have been measured by ultrafast pump-probe transient absorption spectroscopy over a 80-320 K temperature range in 2-methyl tetrahydrofuran (2-MTHF) solvent. Analyses of the photoinduced charge-separation (CS) rate data are presented within the context of several different theoretical frameworks. Experiments show that at higher temperatures the initially prepared 2a-Zn vibronically excited S1 state relaxes on an ultrafast time scale, and ET is observed exclusively from the equilibrated lowest-energy S1 state (CS1). As the temperature decreases, production of the photoinduced charge-separated state directly from the vibrationally unrelaxed S1 state (CS2) becomes competitive with the vibrational relaxation time scale. At the lowest experimentally interrogated temperature ( approximately 80 K), CS2 defines the dominant ET pathway. ET from the vibrationally unrelaxed S1 state is temperature-independent and manifests a subpicosecond time constant; in contrast, the CS1 rate constant is temperature-dependent, exhibiting time constants ranging from 4x10(10) s(-1) to 4x10(11) s(-1) and is correlated strongly with the temperature-dependent solvent dielectric relaxation time scale over a significant temperature domain. Respective electronic coupling matrix elements for each of these photoinduced CS1 and CS2 pathways were determined to be approximately 50 and approximately 100 cm-1. This work not only documents a rare, if not unique, example of a system where temperature-dependent photoinduced charge-separation (CS) dynamics from vibrationally relaxed and unrelaxed S1 states can be differentiated, but also demonstrates a temperature-dependent mechanistic transition of photoinduced CS from the nonadiabatic to the solvent-controlled adiabatic regime, followed by a second temperature-dependent mechanistic evolution where CS becomes decoupled from solvent dynamics and is determined by the extent to which the vibrationally unrelaxed S1 state is populated.

Authors
Kang, YK; Duncan, TV; Therien, MJ
MLA Citation
Kang, YK, Duncan, TV, and Therien, MJ. "Temperature-dependent mechanistic transition for photoinduced electron transfer modulated by excited-state vibrational relaxation dynamics." J Phys Chem B 111.24 (June 21, 2007): 6829-6838.
PMID
17489628
Source
pubmed
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
111
Issue
24
Publish Date
2007
Start Page
6829
End Page
6838
DOI
10.1021/jp070414f

Controlling Bulk Optical Properties of Emissive Polymersomes Through Intramembranous Polymer-Fluorophore Interactions.

Interdisciplinary investigation at the interface of chemistry, engineering, and medicine has enabled the development of self-assembled nanomaterials with novel biochemical and electro-optical properties. We have recently shown that emissive polymersomes, polymer vesicles incorporating porphyrin-based fluorophores, feature large integrated-emission oscillator strengths and narrow emission bands; these nanoscale assemblies can be further engineered to fluoresce at discrete wavelengths throughout the visible and near-infrared (NIR) spectral domains. As such, emissive polymersomes effectively define an organic-based family of soft-matter quantum-dot analogs that possess not only impressive optical properties, but also tunable physical and biomaterial characteristics relative to inorganic fluorescent nanoparticles.Here, we expand upon our initial studies on poly(ethyleneoxide)-block-poly(butadiene)-based vesicles to examine fluorophore membrane-loading in other polymersome systems. Through modulation of fluorophore ancilliary group substituents and choice of polymer chain chemistries, we are able to predictably control intramembranous polymer-fluorophore interactions; these phenomena, in turn, influence the nature of fluorophore solvation, local dielectric environment, and emission quantum yield within emissive polymersome assemblies. By utilizing different classes of vesicle-generating diblock copolymers, including bioresorbable poly(ethyleneoxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) and poly(ethyleneoxide)-block-poly(gamma-methyl-epsilon-caprolactone) (PEO-b-PMCL), we ascertain general principles important for engineering nanoscale optical vesicles. Further, this work heralds the first generation of fully-biodegradable fluorescent nanoparticles suitable for deep-tissue in vivo imaging.

Authors
Ghoroghchian, PP; Frail, PR; Li, G; Zupancich, JA; Bates, FS; Hammer, DA; Therien, MJ
MLA Citation
Ghoroghchian, PP, Frail, PR, Li, G, Zupancich, JA, Bates, FS, Hammer, DA, and Therien, MJ. "Controlling Bulk Optical Properties of Emissive Polymersomes Through Intramembranous Polymer-Fluorophore Interactions." Chem Mater 19.6 (March 20, 2007): 1309-1318.
PMID
19079789
Source
pubmed
Published In
Chemistry of Materials
Volume
19
Issue
6
Publish Date
2007
Start Page
1309
End Page
1318
DOI
10.1021/cm062427w

Tat-functionalized near-infrared emissive polymersomes for dendritic cell labeling.

Dendritic cells (DCs) play a pivotal role in both immune tolerance and the initiation of immunological responses. The ability to track DCs in vivo is imperative for the development of DC-based cellular therapies and to advance our understanding of DC function and pathophysiology. Here, we conjugate a cell permeable peptide, Tat, to near-infrared (NIR) emissive polymersomes in order to enable efficient intracellular delivery for future DC tracking with these optical probes. NIR imaging allows quantitative, repetitive, in vivo detection of fluorophore-laden cells, at centimeter tissue depths without disturbing cellular function. Flow cytometry and confocal microscopy results indicate that Tat-mediated polymersome delivery to DCs is concentration and time dependent, resulting in punctate intracellular localization. Further, loading cells with Tat NIR emissive polymersomes does not interfere with cytokine-induced DC maturation and has modest effects on DC viability, but has a significant effect on mature DC-induced activation of naive T cells. We observe significant uptake of NIR emissive polymersomes when conjugated to the peptide, with a lower detection limit of 5000 labeled DCs. The extent of polymersome delivery is estimated as 70 000 +/- 10 000 vesicles/cell, equivalent to 0.7 +/- 0.1 fmol of NIR fluorophore. Our studies will enable future in vivo tracking of ex vivo labeled DCs by NIR fluorescence based imaging.

Authors
Christian, NA; Milone, MC; Ranka, SS; Li, G; Frail, PR; Davis, KP; Bates, FS; Therien, MJ; Ghoroghchian, PP; June, CH; Hammer, DA
MLA Citation
Christian, NA, Milone, MC, Ranka, SS, Li, G, Frail, PR, Davis, KP, Bates, FS, Therien, MJ, Ghoroghchian, PP, June, CH, and Hammer, DA. "Tat-functionalized near-infrared emissive polymersomes for dendritic cell labeling." Bioconjug Chem 18.1 (January 2007): 31-40.
PMID
17226955
Source
pubmed
Published In
Bioconjugate Chemistry
Volume
18
Issue
1
Publish Date
2007
Start Page
31
End Page
40
DOI
10.1021/bc0601267

Modulation of dark conductivity over a 1 × 10-12 to 1 × 10-5 S/cm range through ancillary group modification in amorphous solids of ethyne-bridged (porphinato)zinc(II) oligomers

Modulation of dark conductivity (DC) over a 1 × 10-12 to 1 × 10-5 S/cm range through ancillary group modification in amorphous solids of ethylene-bridged (Prophinato)zinc (II) (PZn n)oligomers was analyzed. Results from atomic absorption spectroscopy show that the oligomers exhibit large intermolecular interactions in the solid state. The oligomer powder samples are amorphous with no discernible diffraction peaks while the oligomers are decomposed at 220°C. The results also show that PZnn species bearing stabilizing groups behave as insulators over the PZn1-PZn5 length scale. The substituents show augmentation of DC with increasing oligomer length, while the substituents enhance oligomeric interchain electronic coupling in the solid state.

Authors
Frail, PR; Susumu, K; Huynh, M; Fong, J; Kikkawa, JM; Therien, MJ
MLA Citation
Frail, PR, Susumu, K, Huynh, M, Fong, J, Kikkawa, JM, and Therien, MJ. "Modulation of dark conductivity over a 1 × 10-12 to 1 × 10-5 S/cm range through ancillary group modification in amorphous solids of ethyne-bridged (porphinato)zinc(II) oligomers." Chemistry of Materials 19.25 (2007): 6062-6064.
Source
scival
Published In
Chemistry of Materials
Volume
19
Issue
25
Publish Date
2007
Start Page
6062
End Page
6064
DOI
10.1021/cm701914a

Pharmacokinetic assessment of a polymersome-based molecular beacon by in vivo fluorescence monitoring

Authors
Sunar, U; Ghoroghchian, PP; Intes, X; Therien, MJ; Hammer, DA; Yodh, AG
MLA Citation
Sunar, U, Ghoroghchian, PP, Intes, X, Therien, MJ, Hammer, DA, and Yodh, AG. "Pharmacokinetic assessment of a polymersome-based molecular beacon by in vivo fluorescence monitoring." Progress in Biomedical Optics and Imaging - Proceedings of SPIE 6434 (2007).
Source
scival
Published In
Proceedings of SPIE
Volume
6434
Publish Date
2007
DOI
10.1117/12.700802

Electronic modulation of hyperpolarizable (porphinato)zinc(II) chromophores featuring ethynylphenyl-, ethynylthiophenyl-, ethynylthiazolyl-, and ethynylbenzothiazolyl-based electron-donating and -accepting moieties.

A series of conjugated (porphinato)zinc(II)-based chromophores structurally related to [5-(4-dimethylaminophenylethynyl)-15-(5-nitrothienyl-2-ethynyl)-10,20-bis(3,5-bis(3,3-dimethyl-1-butyloxy)phenyl)]zinc(II) were synthesized using metal-catalyzed cross-coupling reactions involving [5-bromo-15-triisopropylsilylethynyl-10,20-diarylporphinato]zinc(II), [5-bromo-15-(4-dimethylaminophenylethynyl)-10,20-diarylporphinato]zinc(II), [5-(4-dimethylaminophenylethynyl)-15-ethynyl-10,20-diarylporphinato]zinc(II), and [5-(4-nitrophenylethynyl)-15-ethynyl-10,20-diarylporphinato]zinc(II), along with appropriately functionalized aryl, thienyl (or thiophenyl), thiazolyl, benzothiazolyl, and carbazolyl precursors. The linear and nonlinear optical properties of these asymmetrically 5,15-substitued-(10,20-diarylporphinato)zinc(II) chromophores that bear either 2-(9H-carbazol-9-yl)-thiophen-5-yl-ethynyl, 4-dimethylaminophenylethynyl, or 2-(N,N-diphenylamino)thiophen-5-yl-ethynyl electron-releasing groups and an electron-withdrawing group selected from 2-formyl-thiophen-5-yl-ethynyl, 2-(2,2-dicyanovinyl)-thiophen-5-yl-ethynyl, 4-nitrophenylethynyl, 6-nitrobenzothiazol-2-yl-ethynyl, or 5-nitrothiazol-2-yl-ethynyl are reported. The dynamic hyperpolarizabilities of these compounds were determined from hyper-Rayleigh light scattering measurements carried out at a fundamental incident irradiation wavelength (lambda(inc)) of 1300 nm; these measured beta1300 values ranged from 690 --> 1400 x 10(-30) esu. These data (i) show that these neutral dipolar molecules express substantial beta1300 values, (ii) highlight that reductions in the magnitude of the aromatic stabilization energy of (porphinato)metal-pendant arylethynyl groups have a significant impact upon the magnitude of the molecular hyperpolarizability, and (iii) provide insights into advantageous design modifications for closely related structures having potential utility in long-wavelength electrooptic applications.

Authors
Zhang, T-G; Zhao, Y; Song, K; Asselberghs, I; Persoons, A; Clays, K; Therien, MJ
MLA Citation
Zhang, T-G, Zhao, Y, Song, K, Asselberghs, I, Persoons, A, Clays, K, and Therien, MJ. "Electronic modulation of hyperpolarizable (porphinato)zinc(II) chromophores featuring ethynylphenyl-, ethynylthiophenyl-, ethynylthiazolyl-, and ethynylbenzothiazolyl-based electron-donating and -accepting moieties." Inorg Chem 45.24 (November 27, 2006): 9703-9712.
PMID
17112266
Source
pubmed
Published In
Inorganic Chemistry
Volume
45
Issue
24
Publish Date
2006
Start Page
9703
End Page
9712
DOI
10.1021/ic060898e

Structural studies of amphiphilic 4-helix bundle peptides incorporating designed extended chromophores for nonlinear optical biomolecular materials.

Extended conjugated chromophores containing (porphinato)zinc components that exhibit large optical polarizabilities and hyperpolarizabiliites are incorporated into amphiphilic 4-helix bundle peptides via specific axial histidyl ligation of the metal. The bundle's designed amphiphilicity enables vectorial orientation of the chromophore/peptide complex in macroscopic monolayer ensembles. The 4-helix bundle structure is maintained upon incorporation of two different chromophores at stoichiometries of 1-2 per bundle. The axial ligation site appears to effectively control the position of the chromophore along the length of the bundle.

Authors
Strzalka, J; Xu, T; Tronin, A; Wu, SP; Miloradovic, I; Kuzmenko, I; Gog, T; Therien, MJ; Blasie, JK
MLA Citation
Strzalka, J, Xu, T, Tronin, A, Wu, SP, Miloradovic, I, Kuzmenko, I, Gog, T, Therien, MJ, and Blasie, JK. "Structural studies of amphiphilic 4-helix bundle peptides incorporating designed extended chromophores for nonlinear optical biomolecular materials." Nano Lett 6.11 (November 2006): 2395-2405.
PMID
17090064
Source
pubmed
Published In
Nano Letters
Volume
6
Issue
11
Publish Date
2006
Start Page
2395
End Page
2405
DOI
10.1021/nl062092h

Incorporation of designed extended chromophores into amphiphilic 4-helix bundle peptides for nonlinear optical biomolecular materials.

Multipigment ensembles that feature (porphinato)metal components and appropriate ethyne- and oligoyne-based chromophore-to-chromophore connectivity can manifest large optical polarizabilities and hyperpolarizabilities by design. Their vectorial orientation and local environment are controlled upon incorporation into designed amphiphilic 4-helix bundle peptides via axial histidyl ligation without disturbing the peptide's helical secondary structure. The chromophore/peptide stoichiometry can be tuned by varying the peptide's oligomeric state. The chromophore/peptide complexes are thermally stable, making them ideal candidates for the fabrication of nonlinear optical biomolecular materials.

Authors
Xu, T; Wu, SP; Miloradovic, I; Therien, MJ; Blasie, JK
MLA Citation
Xu, T, Wu, SP, Miloradovic, I, Therien, MJ, and Blasie, JK. "Incorporation of designed extended chromophores into amphiphilic 4-helix bundle peptides for nonlinear optical biomolecular materials." Nano Lett 6.11 (November 2006): 2387-2394.
PMID
17090063
Source
pubmed
Published In
Nano Letters
Volume
6
Issue
11
Publish Date
2006
Start Page
2387
End Page
2394
DOI
10.1021/nl062091p

Ethyne-bridged (porphinato)zinc(II)-(porphinato)iron(III) complexes: phenomenological dependence of excited-state dynamics upon (porphinato)iron electronic structure.

We report the synthesis, spectroscopy, potentiometric properties, and excited-state dynamical studies of 5-[(10,20-di-((4-ethyl ester)methylene-oxy)phenyl)porphinato]zinc(II)-[5'-[(10',20'- di-((4-ethyl ester)methylene-oxy)phenyl)porphinato]iron(III)-chloride]ethyne (PZn-PFe-Cl), along with a series of related supermolecules ([PZn-PFe-(L)1,2]+ species) that possess a range of metal axial ligation environments (L = pyridine, 4-cyanopyridine, 2,4,6-trimethylpyridine (collidine), and 2,6-dimethylpyridine (2,6-lutidine)). Relevant monomeric [(porphinato)iron-(ligand)1,2]+ ([PFe(L)1,2]+) benchmarks have also been synthesized and fully characterized. Ultrafast pump-probe transient absorption spectroscopic experiments that interrogate the initially prepared electronically excited states of [PFe(L)1,2]+ species bearing nonhindered axial ligands demonstrated subpicosecond-to-picosecond relaxation dynamics to the ground electronic state. Comparative pump-probe transient absorption experiments that interrogate the initially prepared excited states of PZn-PFe-Cl, [PZn-PFe-(py)2]+, [PZn-PFe-(4-CN-py)2]+, [PZn-PFe-(collidine)]+, and [PZn-PFe-(2,6-lutidine)]+ demonstrate that the spectra of all these species are dominated by a broad, intense NIR S1 --> Sn transient absorption manifold. While PZn-PFe-Cl, [PZn-PFe-(py)2]+, and [PZn-PFe-(4-CN-py)2]+ evince subpicosecond and picosecond time-scale relaxation of their respective initially prepared electronically excited states to the ground state, the excited-state dynamics observed for [PZn-PFe-(2,6-lutidine)]+ and [PZn-PFe-(collidine)]+ show fast relaxation to a [PZn+-PFe(II)] charge-separated state having a lifetime of nearly 1 ns. Potentiometric data indicate that while DeltaGCS for [PZn-PFe-(L)1,2]+ species is strongly influenced by the PFe+ ligation state [ligand (DeltaGCS): 4-cyanopyridine (-0.79 eV) < pyridine (-1.04 eV) < collidine (-1.35 eV) < chloride (-1.40 eV); solvent = CH2Cl2], the pump-probe transient absorption dynamical data demonstrate that the nature of the dominant excited-state decay pathway is not correlated with the thermodynamic driving force for photoinduced charge separation, but depends on the ferric ion ligation mode. These data indicate that sterically bulky axial ligands that drive a pentacoordinate PFe center and a weak metal axial ligand interaction serve to sufficiently suppress the normally large magnitude nonradiative decay rate constants characteristic of (porphinato)iron(III) complexes, and thus make electron transfer a competitive excited-state deactivation pathway.

Authors
Duncan, TV; Wu, SP; Therien, MJ
MLA Citation
Duncan, TV, Wu, SP, and Therien, MJ. "Ethyne-bridged (porphinato)zinc(II)-(porphinato)iron(III) complexes: phenomenological dependence of excited-state dynamics upon (porphinato)iron electronic structure." J Am Chem Soc 128.32 (August 16, 2006): 10423-10435.
PMID
16895407
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
128
Issue
32
Publish Date
2006
Start Page
10423
End Page
10435
DOI
10.1021/ja061388m

Exceptional near-infrared fluorescence quantum yields and excited-state absorptivity of highly conjugated porphyrin arrays.

We show that meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZnn structures) define exceptional low band gap organic materials that possess both large magnitude NIR S1 --> S0 fluorescence quantum yields and substantial S1 --> Sn absorptive cross-sections, tunable over a wide 850-1400 nm spectral window. These PZnn species possess fluorescence quantum yields (phif values) comparable to the highest reported for NIR laser dyes in the 750-900 nm regime; importantly, these emitters do not suffer from commonly cited tricarbocyanine dye drawbacks of poor photostability and substantial phif sensitivity to solvent polarity. Furthermore, tauo (kr-1) values determined using the Strickler-Berg method highlight the close correlation of fluorescence quantum yields with S0 --> S1 integrated oscillator strength and demonstrate a rare if not unique example of broad NIR spectral domain fluorescence energy modulation, where phif magnitudes follow a simple Strickler-Berg relationship.

Authors
Duncan, TV; Susumu, K; Sinks, LE; Therien, MJ
MLA Citation
Duncan, TV, Susumu, K, Sinks, LE, and Therien, MJ. "Exceptional near-infrared fluorescence quantum yields and excited-state absorptivity of highly conjugated porphyrin arrays." J Am Chem Soc 128.28 (July 19, 2006): 9000-9001.
PMID
16834350
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
128
Issue
28
Publish Date
2006
Start Page
9000
End Page
9001
DOI
10.1021/ja061897o

Conjugated chromophore arrays with unusually large hole polaron delocalization lengths.

We report variable temperature X-band EPR spectroscopic data for the cation radical states of meso-to-meso ethyne-bridged (porphinato)zinc(II) (PZnn) oligomers. These [PZn2-PZn7]+ species span an average 18-75 A length scale and display peak-to-peak EPR line widths (DeltaBp-p) that diminish with conjugation length. Analysis of these EPR data show that PZnn+ structures possess the largest hole polaron delocalization lengths yet measured; experiments carried out over a 4-298 K temperature domain demonstrate remarkably that the charge delocalization length remains invariant with temperature. These cation radical EPR data are well described by a stochastic, near barrierless, one-dimensional charge hopping model developed by Norris for N equivalent sites on a polymer chain, where the theoretical EPR line width is given by DeltaBp-p(N-mer) = (1/N1/2)DeltaBp-p(monomer); PZnn+ oligomers are the first such systems to verify a Norris-type hole delocalization mechanism over a substantial ( approximately 75 A) length scale. Given the time scale of the EPR measurement, these data show that either (i) Franck-Condon effects are incapable of driving charge localization in [PZn2-PZn7]+, resulting in cation radical wave functions which are globally delocalized over a spatial domain that is large with respect to established benchmarks for hole-doped conjugated materials, or (ii) polaron hopping rates in these oligomers exceed 107 s-1, even at 4 K. Finally, this study demonstrates that polymeric building blocks having low magnitude inner sphere reorganization energies enable the development of electronic materials having long polaron delocalization lengths.

Authors
Susumu, K; Frail, PR; Angiolillo, PJ; Therien, MJ
MLA Citation
Susumu, K, Frail, PR, Angiolillo, PJ, and Therien, MJ. "Conjugated chromophore arrays with unusually large hole polaron delocalization lengths." J Am Chem Soc 128.26 (July 5, 2006): 8380-8381.
PMID
16802786
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
128
Issue
26
Publish Date
2006
Start Page
8380
End Page
8381
DOI
10.1021/ja0614823

Bioresorbable Vesicles Formed through Spontaneous Self-Assembly of Amphiphilic Poly(ethylene oxide)-block-polycaprolactone.

Authors
Ghoroghchian, PP; Li, G; Levine, DH; Davis, KP; Bates, FS; Hammer, DA; Therien, MJ
MLA Citation
Ghoroghchian, PP, Li, G, Levine, DH, Davis, KP, Bates, FS, Hammer, DA, and Therien, MJ. "Bioresorbable Vesicles Formed through Spontaneous Self-Assembly of Amphiphilic Poly(ethylene oxide)-block-polycaprolactone." Macromolecules 39.5 (March 7, 2006): 1673-1675.
PMID
20975926
Source
pubmed
Published In
Macromolecules
Volume
39
Issue
5
Publish Date
2006
Start Page
1673
End Page
1675
DOI
10.1021/ma0519009

Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds

Several materials that have been demonstrated to have very large excited state NIR absorption coefficients have been examined by nanosecond Z-scan and nonlinear transmission experiments and demonstrate large decreases in transmission with increasing fluence. © 2005 OSA/CLEO 2005.

Authors
Pong, RGS; Flom, SR; Shirk, JS; Duncan, TV; Therien, MJ
MLA Citation
Pong, RGS, Flom, SR, Shirk, JS, Duncan, TV, and Therien, MJ. "Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds." Optics InfoBase Conference Papers (January 1, 2006).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2006

Erratum: Computational de novo design and characterization of a four-helix bundle protein that selectively binds a nonbiological cofactor (Journal of the American Chemical Society (2005) 127 (1346-1347))

Authors
Cochran, FV; Wu, SP; Wang, W; Nanda, V; Saven, JG; Therien, MJ; DeGrado, WF
MLA Citation
Cochran, FV, Wu, SP, Wang, W, Nanda, V, Saven, JG, Therien, MJ, and DeGrado, WF. "Erratum: Computational de novo design and characterization of a four-helix bundle protein that selectively binds a nonbiological cofactor (Journal of the American Chemical Society (2005) 127 (1346-1347))." Journal of the American Chemical Society 128.2 (2006): 663--.
Source
scival
Published In
Journal of the American Chemical Society
Volume
128
Issue
2
Publish Date
2006
Start Page
663-
DOI
10.1021/ja059923q

Coordination compounds for functional nonlinear optics: Enhancing and switching the second-order nonlinear optical responses

In this work, we describe the second-order nonlinear optical (NLO) properties of a number of chromophores that feature transition metal ions in classic coordination environments. We focused our attention on the advantages of diese species over standard hyperpolarizable chromophores based on conventional all-organic frameworks. For example, studies of Ruthenium(II)-based electron donor-acceptor (D-A) polyenes illustrate that transition metal-based compounds can show atypical conjugation-length dependences of the observed hyperpolarizability relative to closely related organic NLO chromophores. Likewise, the second-order NLO responses observed for highly conjugated (polypyridyl)metal(phorphinato)zinc(II) chromophores can be extraordinarily large, illustrating how coupled oscillator photophysics can be exploited to design materials with record hyperpolarizabilities at telecommunication-relevant wavelengths. Finally, our work demonstrates that the presence of a transition metal ion in NLO chromophores makes possible new strategies to switch and gate NLO responses voltammetrically. © 2006 American Chemical Society.

Authors
Asselberghs, I; Therien, MJ; Coe, BJ; Mccleverty, JA; Clays, K
MLA Citation
Asselberghs, I, Therien, MJ, Coe, BJ, Mccleverty, JA, and Clays, K. "Coordination compounds for functional nonlinear optics: Enhancing and switching the second-order nonlinear optical responses." ACS Symposium Series 928 (2006): 527-540.
Source
scival
Published In
ACS Symposium Series
Volume
928
Publish Date
2006
Start Page
527
End Page
540

One-dimensional diffusion-limited relaxation of photoexcitations in suspensions of single-walled carbon nanotubes

We report pump-probe transient absorption spectroscopy on carbon nanotubes with a high initial excitation density. We find that the recovery of the ground state optical absorption is well described by a 1 t relaxation, indicating that the long time population relaxation is controlled by one-dimensional diffusion limited two body recombination. © 2006 The American Physical Society.

Authors
Russo, RM; Mele, EJ; Kane, CL; Rubtsov, IV; Therien, MJ; Luzzi, DE
MLA Citation
Russo, RM, Mele, EJ, Kane, CL, Rubtsov, IV, Therien, MJ, and Luzzi, DE. "One-dimensional diffusion-limited relaxation of photoexcitations in suspensions of single-walled carbon nanotubes." Physical Review B - Condensed Matter and Materials Physics 74.4 (2006).
Source
scival
Published In
Physical Review B - Condensed Matter and Materials Physics
Volume
74
Issue
4
Publish Date
2006
DOI
10.1103/PhysRevB.74.041405

Quantitative membrane loading of polymer vesicles

We utilize a series of structurally homologous, multi-porphyrin-based, fluorophores (PBFs) in order to explore the capacity of polymer vesicles (polymersomes) to stably incorporate large hydrophobic molecules, non-covalently within their thick lamellar membranes. Through aqueous hydration of dry, uniform thin-films of amphiphilic polymer and PBF species deposited on Teflon, self-assembled polymersomes are readily generated incorporating the hydrophobic fluorophores in prescribed molar ratios within their membranes. The size-dependent spectral properties of the PBFs allow for ready optical verification (via steady-state absorption and emission spectroscopy) of the extent of vesicle membrane loading and enable delineation of intermembranous molecular interactions. The resultant effects of PBF membrane-loading on polymersome thermodynamic and mechanical stability are further assessed by cryogenic transmission electron microscopy (cryo-TEM) and micropipet aspiration, respectively. We demonstrate that polymersomes can be loaded at up to 10 mol/wt% concentrations, with hydrophobic molecules that possess sizes comparable to those of large pharmaceutical conjugates (e.g. ranging 1.4-5.4 nm in length and Mw = 0.7-5.4 kg mol-1), without significantly compromising the robust thermodynamic and mechanical stabilities of these synthetic vesicle assemblies. Due to membrane incorporation, hydrophobic encapsulants are effectively prevented from self-aggregation, able to be highly concentrated in aqueous solution, and successfully shielded from deleterious environmental interactions. Together, these studies present a generalized paradigm for the generation of complex multi-functional materials that combine both hydrophilic and hydrophobic agents, in mesoscopic dimensions, through cooperative self-assembly. © The Royal Society of Chemistry 2006.

Authors
Ghoroghchian, PP; Lin, JJ; Brannan, AK; Frail, PR; Bates, FS; Therien, MJ; Hammer, DA
MLA Citation
Ghoroghchian, PP, Lin, JJ, Brannan, AK, Frail, PR, Bates, FS, Therien, MJ, and Hammer, DA. "Quantitative membrane loading of polymer vesicles." Soft Matter 2.11 (2006): 973-980.
Source
scival
Published In
Soft Matter
Volume
2
Issue
11
Publish Date
2006
Start Page
973
End Page
980
DOI
10.1039/b604212k

Broad spectral domain fluorescence wavelength modulation of visible and near-infrared emissive polymersomes.

Incorporation of an extended family of multi[(porphinato)zinc(II)] (PZn)-based supermolecular fluorophores into the lamellar membranes of polymersomes (50 nm to 50 mum diameter polymer vesicles) gives rise to electrooptically diverse nano-to-micron (meso) scale soft materials. Studies that examine homogeneous suspensions of 100 nm diameter emissive polymersomes demonstrate fluorescence energy modulation over a broad spectral domain of the visible and near-infrared (600-900 nm). These polymersomal structures highlight that the nature of intermembranous polymer-to-fluorophore contacts depends on the position and identity of the porphyrins' phenyl ring substituents. Emissive polymersomes are shown to possess reduced spectral heterogeneity with respect to the established optical signatures of these PZn-based supermolecular fluorophores in solution; additionally, selection of fluorophore ancillary substituents predictably controls the nature of polymer-emitter noncovalent interactions to provide an important additional mechanism to further modulate the fluorescence band maxima of these meso-scale emissive vesicles.

Authors
Ghoroghchian, PP; Frail, PR; Susumu, K; Park, T-H; Wu, SP; Uyeda, HT; Hammer, DA; Therien, MJ
MLA Citation
Ghoroghchian, PP, Frail, PR, Susumu, K, Park, T-H, Wu, SP, Uyeda, HT, Hammer, DA, and Therien, MJ. "Broad spectral domain fluorescence wavelength modulation of visible and near-infrared emissive polymersomes." J Am Chem Soc 127.44 (November 9, 2005): 15388-15390.
PMID
16262400
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
127
Issue
44
Publish Date
2005
Start Page
15388
End Page
15390
DOI
10.1021/ja055571b

Amphiphilic four-helix bundle peptides designed for light-induced electron transfer across a soft interface.

A family of four-helix bundle peptides were designed to be amphiphilic, possessing distinct hydrophilic and hydrophobic domains along the length of the bundle's exterior. This facilitates their vectorial insertion across a soft interface between polar and nonpolar media. Their design also now provides for selective incorporation of electron donor and acceptor cofactors within each domain. This allows translation of the designed intramolecular electron transfer along the bundle axis into a macroscopic charge separation across the interface.

Authors
Ye, S; Discher, BM; Strzalka, J; Xu, T; Wu, SP; Noy, D; Kuzmenko, I; Gog, T; Therien, MJ; Dutton, PL; Blasie, JK
MLA Citation
Ye, S, Discher, BM, Strzalka, J, Xu, T, Wu, SP, Noy, D, Kuzmenko, I, Gog, T, Therien, MJ, Dutton, PL, and Blasie, JK. "Amphiphilic four-helix bundle peptides designed for light-induced electron transfer across a soft interface." Nano Lett 5.9 (September 2005): 1658-1667.
PMID
16159202
Source
pubmed
Published In
Nano Letters
Volume
5
Issue
9
Publish Date
2005
Start Page
1658
End Page
1667
DOI
10.1021/nl050542k

Generalized Mulliken-Hush analysis of electronic coupling interactions in compressed pi-stacked porphyrin-bridge-quinone systems.

Donor-acceptor interactions were investigated in a series of unusually rigid, cofacially compressed pi-stacked porphyrin-bridge-quinone systems. The two-state generalized Mulliken-Hush (GMH) approach was used to compute the coupling matrix elements. The theoretical coupling values evaluated with the GMH method were obtained from configuration interaction calculations using the INDO/S method. The results of this analysis are consistent with the comparatively soft distance dependences observed for both the charge separation and charge recombination reactions. Theoretical studies of model structures indicate that the phenyl units dominate the mediation of the donor-acceptor coupling and that the relatively weak exponential decay of rate with distance arises from the compression of this pi-electron stack.

Authors
Zheng, J; Kang, YK; Therien, MJ; Beratan, DN
MLA Citation
Zheng, J, Kang, YK, Therien, MJ, and Beratan, DN. "Generalized Mulliken-Hush analysis of electronic coupling interactions in compressed pi-stacked porphyrin-bridge-quinone systems." J Am Chem Soc 127.32 (August 17, 2005): 11303-11310.
PMID
16089459
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
127
Issue
32
Publish Date
2005
Start Page
11303
End Page
11310
DOI
10.1021/ja050984y

Design, synthesis, linear, and nonlinear optical properties of conjugated (porphinato)zinc(II)-based donor-acceptor chromophores featuring nitrothiophenyl and nitrooligothiophenyl electron-accepting moieties.

An extensive series of conjugated (porphinato)zinc(II)-based chromophores featuring nitrothiophenyl and nitrooligothiophenyl electron-accepting moieties has been synthesized using metal-catalyzed cross-coupling reactions involving [5-bromo-15-triisopropylsilylethynyl-10,20-diarylporphinato]zinc(II) and an unusual electron-rich Suzuki-porphyrin synthon, [5-(4-dimethylaminophenylethynyl)-15-(4',4',5',5'-tetramethyl[1',3',2']dioxaborolan-2'-yl)-10,20-diarylporphinato]zinc(II), with appropriately functionalized aryl and thienyl precursors. These donor-acceptor chromophores feature thiophenyl, [2,2']bithiophenyl, and [2,2';5',2' ']terthiophenyl units terminated with a 5-nitro group; one series of structures features these acceptor moieties appended directly to the porphyrin macrocycle meso-carbon position, while a second set utilizes an intervening meso-ethynyl moiety to modify porphyrin-to-thiophene conjugation. The dynamic hyperpolarizability of these compounds was determined from hyper-Rayleigh light scattering (HRS) measurements carried out at fundamental incident irradiation wavelengths (lambda(inc)) of 800 and 1300 nm; interestingly, measured beta(1300) values ranged from 650 --> 4350 x 10(-30) esu. The combined linear and nonlinear optical properties of these compounds challenge the classical concept of the nonlinearity/transparency tradeoff in charge-transfer chromophores: the magnitude of the molecular hyperpolarizability is observed to vary substantially despite approximately uniform ground-state absorptive signatures for a given porphyrin-to-thiophene linkage topology. These data show that these neutral dipolar molecules can express substantial beta(1300) values; such conjugated, electronically asymmetric porphyrin-thiophene chromophores may thus find utility for electrooptic applications at telecom-relevant wavelengths.

Authors
Zhang, T-G; Zhao, Y; Asselberghs, I; Persoons, A; Clays, K; Therien, MJ
MLA Citation
Zhang, T-G, Zhao, Y, Asselberghs, I, Persoons, A, Clays, K, and Therien, MJ. "Design, synthesis, linear, and nonlinear optical properties of conjugated (porphinato)zinc(II)-based donor-acceptor chromophores featuring nitrothiophenyl and nitrooligothiophenyl electron-accepting moieties." J Am Chem Soc 127.27 (July 13, 2005): 9710-9720.
PMID
15998075
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
127
Issue
27
Publish Date
2005
Start Page
9710
End Page
9720
DOI
10.1021/ja0402553

Near-infrared optical imaging of B16 melanoma cells via low-density lipoprotein-mediated uptake and delivery of high emission dipole strength tris[(porphinato)zinc(II)] fluorophores.

Meso-to-meso ethyne-bridged tris[(porphinato)zinc(II)] (PZn(3)) near-infrared (NIR) fluorophores (lambda(em)(max) approximately 800 nm) can be rendered sufficiently amphiphilic to enable their facile incorporation into the hydrophobic core of the apo form of low-density lipoprotein (apo-LDL). These NIR fluorophores are notable in that they manifest low energy excited states polarized exclusively along the long axis of the supermolecule, broad spectral coverage of the visible and high energy NIR spectral domains, intense S(0)-->S(1) transition moments, and comparably large S(1)-->S(0) emission dipole strengths. The reconstituted LDL(PZn(3)) proteins can be used to deliver rapidly hundreds of copies of PZn(3) to a given murine B16 melanoma cell via LDL receptor-mediated endocytosis. PZn(3)-based NIRFs and their corresponding LDL(PZn(3)) proteins have been shown to display minimal cytotoxicity. Confocal NIR fluorescence microscopy evinces that B16 cells can be imaged at very low doses (approximately nM) of NIRF. The highly attractive photophysical properties of PZn(3) and closely related chromophores, coupled with their lack of toxicity and compatibility with uptake into apo-LDL and subsequent rapid delivery to B16 cells via LDLr-mediated endocytosis, suggest the potential utility of this platform for NIR optical imaging of cancer cells in vivo.

Authors
Wu, SP; Lee, I; Ghoroghchian, PP; Frail, PR; Zheng, G; Glickson, JD; Therien, MJ
MLA Citation
Wu, SP, Lee, I, Ghoroghchian, PP, Frail, PR, Zheng, G, Glickson, JD, and Therien, MJ. "Near-infrared optical imaging of B16 melanoma cells via low-density lipoprotein-mediated uptake and delivery of high emission dipole strength tris[(porphinato)zinc(II)] fluorophores." Bioconjug Chem 16.3 (May 2005): 542-550.
PMID
15898720
Source
pubmed
Published In
Bioconjugate Chemistry
Volume
16
Issue
3
Publish Date
2005
Start Page
542
End Page
550
DOI
10.1021/bc0497416

Potentiometric, electronic structural, and ground- and excited-state optical properties of conjugated bis[(porphinato)zinc(II)] compounds featuring proquinoidal spacer units.

We report the synthesis, optical, electrochemical, electronic structural, and transient optical properties of conjugated (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes that possess intervening conjugated Sp structures having varying degrees of proquinoidal character. These supermolecular PZn-Sp-PZn compounds feature Sp moieties {(4,7-diethynylbenzo[c][1,2,5]thiadiazole (E-BTD-E), 6,13-diethynylpentacene (E-PC-E), 4,9-diethynyl-6,7-dimethyl[1,2,5]thiadiazolo[3,4-g]quinoxaline (E-TDQ-E), and 4,8-diethynylbenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (E-BBTD-E)} that regulate frontier orbital energy levels and progressively increase the extent of the quinoidal resonance contribution to the ground and electronically excited states, augmenting the magnitude of electronic communication between terminal (5,-10,20-di(aryl)porphinato)zinc(II) units, relative to that evinced for a bis[(5,5',-10,20-di(aryl)porphinato)zinc(II)]butadiyne benchmark (PZnE-EPZn). Electronic absorption spectra show significant red-shifts of the respective PZn-Sp-PZn x-polarized Q state (S0 --> S1) transition manifold maxima (240-4810 cm(-1)) relative to that observed for PZnE-EPZn. Likewise, the potentiometrically determined PZn-Sp-PZn HOMO-LUMO gaps (E1/2(0/+) - E1/2(-/0)) display correspondingly diminished energy separations that range from 1.88 to 1.11 eV relative to that determined for PZnE-EPZn (2.01 eV). Electronic structure calculations provide insight into the origin of the observed PZn-Sp-PZn electronic and optical properties. Pump-probe transient spectral data for these PZn-Sp-PZn supermolecules demonstrate that the S1 --> S(n) transition manifolds of these species span an unusually broad spectral domain of the NIR. Notably, the absorption maxima of these S1 --> S(n) manifolds can be tuned over a 1000-1600 nm spectral region, giving rise to intense excited-state transitions approximately 4000 cm(-1) lower in energy than that observed for the analogous excited-state absorption maximum of the PZnE-EPZn benchmark; these data highlight the unusually large quinoidal resonance contribution to the low-lying electronically excited singlet states of these PZn-Sp-PZn species. The fact that the length scales of the PZn-Sp-PZn species (approximately 25 angstrom) are small with respect to those of classic conducting polymers, yet possess NIR S1 --> S(n) manifold absorptions lower in energy, underscore the unusual electrooptic properties of these conjugated structures.

Authors
Susumu, K; Duncan, TV; Therien, MJ
MLA Citation
Susumu, K, Duncan, TV, and Therien, MJ. "Potentiometric, electronic structural, and ground- and excited-state optical properties of conjugated bis[(porphinato)zinc(II)] compounds featuring proquinoidal spacer units." J Am Chem Soc 127.14 (April 13, 2005): 5186-5195.
PMID
15810854
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
127
Issue
14
Publish Date
2005
Start Page
5186
End Page
5195
DOI
10.1021/ja040243h

Near-infrared-emissive polymersomes: self-assembled soft matter for in vivo optical imaging.

We demonstrate that synthetic soft materials can extend the utility of natural vesicles, from predominantly hydrophilic reservoirs to functional colloidal carriers that facilitate the biomedical application of large aqueous-insoluble compounds. Near-infrared (NIR)-emissive polymersomes (50-nm- to 50-microm-diameter polymer vesicles) were generated through cooperative self assembly of amphiphilic diblock copolymers and conjugated multi(porphyrin)-based NIR fluorophores (NIRFs). When compared with natural vesicles comprised of phospholipids, polymersomes were uniquely capable of incorporating and uniformly distributing numerous large hydrophobic NIRFs exclusively in their lamellar membranes. Within these sequestered compartments, long polymer chains regulate the mean fluorophore-fluorophore interspatial separation as well as the fluorophore-localized electronic environment. Porphyrin-based NIRFs manifest photophysical properties within the polymersomal matrix akin to those established for these high-emission dipole strength fluorophores in organic solvents, thereby yielding uniquely emissive vesicles. Furthermore, the total fluorescence emanating from the assemblies gives rise to a localized optical signal of sufficient intensity to penetrate through the dense tumor tissue of a live animal. Robust NIR-emissive polymersomes thus define a soft matter platform with exceptional potential to facilitate deep-tissue fluorescence-based imaging for in vivo diagnostic and drug-delivery applications.

Authors
Ghoroghchian, PP; Frail, PR; Susumu, K; Blessington, D; Brannan, AK; Bates, FS; Chance, B; Hammer, DA; Therien, MJ
MLA Citation
Ghoroghchian, PP, Frail, PR, Susumu, K, Blessington, D, Brannan, AK, Bates, FS, Chance, B, Hammer, DA, and Therien, MJ. "Near-infrared-emissive polymersomes: self-assembled soft matter for in vivo optical imaging." Proc Natl Acad Sci U S A 102.8 (February 22, 2005): 2922-2927.
PMID
15708979
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
102
Issue
8
Publish Date
2005
Start Page
2922
End Page
2927
DOI
10.1073/pnas.0409394102

Computational de novo design and characterization of a four-helix bundle protein that selectively binds a nonbiological cofactor.

We report the complete de novo design of a four-helix bundle protein that selectively binds the nonbiological DPP-Fe(III) metalloporphyrin cofactor (DPP-Fe(III) = 5, 15-Di[(4-carboxymethyleneoxy)phenyl]porphinato iron(III)). A tetrameric, D2-symmetric backbone scaffold was constructed to encapsulate two DPP-Fe(III) units through bis(His) coordination. The complete sequence was determined with the aid of the statistical computational design algorithm SCADS. The 34-residue peptide was chemically synthesized. UV-vis and CD spectroscopy, size-exclusion chromatography, and analytical ultracentrifugation indicated the peptide undergoes a transition from a predominantly random coil monomer to an alpha-helical tetramer upon binding DPP-Fe(III). EPR spectroscopy studies indicated the axial imidazole ligands were oriented in a perpendicular fashion, as defined by second-shell interactions that were included in the design. The 1-D 1H NMR spectrum of the assembled protein displayed features of a well-packed interior. The assembled protein possessed functional redox properties different from those of structurally similar systems containing the heme cofactor. The designed peptide demonstrated remarkable cofactor selectivity with a significantly weaker binding affinity for the natural heme cofactor. These findings open a path for the selective incorporation of more elaborate cofactors into designed scaffolds for constructing molecularly well-defined nanoscale materials.

Authors
Cochran, FV; Wu, SP; Wang, W; Nanda, V; Saven, JG; Therien, MJ; DeGrado, WF
MLA Citation
Cochran, FV, Wu, SP, Wang, W, Nanda, V, Saven, JG, Therien, MJ, and DeGrado, WF. "Computational de novo design and characterization of a four-helix bundle protein that selectively binds a nonbiological cofactor." J Am Chem Soc 127.5 (February 9, 2005): 1346-1347.
PMID
15686346
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
127
Issue
5
Publish Date
2005
Start Page
1346
End Page
1347
DOI
10.1021/ja044129a

Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds

Several materials that have been demonstrated to have very large excited state NIR absorption coefficients have been examined by nanosecond Z-scan and nonlinear transmission experiments and demonstrate large decreases in transmission with increasing fluence. © 2005 OSA/CLEO 2005.

Authors
Pong, RGS; Flom, SR; Shirk, JS; Duncan, TV; Therien, MJ
MLA Citation
Pong, RGS, Flom, SR, Shirk, JS, Duncan, TV, and Therien, MJ. "Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds." Optics InfoBase Conference Papers (January 1, 2005).
Source
scopus
Published In
Optics InfoBase Conference Papers
Publish Date
2005

Controlled fabrication of nanogaps in ambient environment for molecular electronics 043109

We have developed a controlled and highly reproducible method of making nanometer-spaced electrodes using electromigration in ambient lab conditions. This advance will make feasible single molecule measurements of macromolecules with tertiary and quaternary structures that do not survive the liquid-helium temperatures at which electromigration is typically performed. A second advance is that it yields gaps of desired tunneling resistance, as opposed to the random formation at liquid-helium temperatures. Nanogap formation occurs through three regimes: First it evolves through a bulk-neck regime where electromigration is triggered at constant temperature, then to a few-atom regime characterized by conductance quantum plateaus and jumps, and finally to a tunneling regime across the nanogap once the conductance falls below the conductance quantum. © 2005 American Institute of Physics.

Authors
Strachan, DR; Smith, DE; Johnston, DE; Park, T-H; Therien, MJ; Bonnell, DA; Johnson, AT
MLA Citation
Strachan, DR, Smith, DE, Johnston, DE, Park, T-H, Therien, MJ, Bonnell, DA, and Johnson, AT. "Controlled fabrication of nanogaps in ambient environment for molecular electronics 043109." Applied Physics Letters 86.4 (2005): 043109-1-043109-3-.
Source
scival
Published In
Applied Physics Letters
Volume
86
Issue
4
Publish Date
2005
Start Page
043109-1-043109-3
DOI
10.1063/1.1857095

Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds

Several materials that have been demonstrated to have very large excited state NIR absorption coefficients have been examined by nanosecond Z-scan and nonlinear transmission experiments and demonstrate large decreases in transmission with increasing fluence.

Authors
Pong, RGS; Flom, SR; Shirk, JS; Duncan, TV; Therien, MJ
MLA Citation
Pong, RGS, Flom, SR, Shirk, JS, Duncan, TV, and Therien, MJ. "Nonlinear transmission of highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds." 2005 Conference on Lasers and Electro-Optics, CLEO 3 (2005): 2004-2006.
Source
scival
Published In
2005 Conference on Lasers and Electro-Optics, CLEO
Volume
3
Publish Date
2005
Start Page
2004
End Page
2006

Highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds: long-lived, high oscillator strength, excited-state absorbers having exceptional spectral coverage of the near-infrared.

Transient dynamical studies of ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)2+ bis-hexafluorophosphate (Ru-PZn), osmium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)2+ bis-hexafluorophosphate (Os-PZn), ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-15-(4'-nitrophenyl)ethynyl-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)2+ bis-hexafluorophosphate (Ru-PZn-A), osmium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-15-(4'-nitrophenyl)ethynyl-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)2+ bis-hexafluorophosphate (Os-PZn-A), and ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-ruthenium(II)-15-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-bis(2,2';6',2' '-terpyridine)4+ tetrakis-hexafluorophosphate (Ru-PZn-Ru), and ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-osmium(II)-15-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-bis(2,2';6',2' '-terpyridine) tetrakis-hexafluorophosphate (Ru-PZn-Os) show that these highly conjugated supermolecular chromophores feature electronically excited states that absorb over broad NIR spectral windows with considerable oscillator strength and manifest lifetimes (1-50 mus) that are extraordinarily long relative to those of classic low band-gap organic materials. The excited-state absorptive domains of these strongly coupled multipigment ensembles can be extensively modulated. For sequential one-photon absorptive processes, these compounds evince large sigmae, sigmae/sigmag, and sigmae - sigmag values. As the combination of all these properties within single chromophoric entities have heretofore lacked precedent within the NIR, these and closely related structures may find particular utility in a variety of technologically important optical-limiting applications.

Authors
Duncan, TV; Rubtsov, IV; Uyeda, HT; Therien, MJ
MLA Citation
Duncan, TV, Rubtsov, IV, Uyeda, HT, and Therien, MJ. "Highly conjugated (polypyridyl)metal-(porphinato)zinc(II) compounds: long-lived, high oscillator strength, excited-state absorbers having exceptional spectral coverage of the near-infrared." J Am Chem Soc 126.31 (August 11, 2004): 9474-9475.
PMID
15291515
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
126
Issue
31
Publish Date
2004
Start Page
9474
End Page
9475
DOI
10.1021/ja0400638

The degree of charge transfer in ground and charge-separated states revealed by ultrafast visible pump/mid-IR probe spectroscopy.

We demonstrate a new femtosecond visible pump/mid-IR probe spectroscopic approach to assess directly the ground- and excited-state degrees of charge transfer (CT) in donor-spacer-acceptor (D-Sp-A) structures. Two classes of (porphinato)zinc(II) (PZn)-based D-Sp-A compounds with either quinonyl (Q) or N-(N'-octyl)pyromellitic diimide (PI) electron acceptors were interrogated. Carbonyl antisymmetric stretching mode frequency domain transient-IR spectra of these species were recorded and analyzed for the Q/PI moieties. These data show that the acceptor mode frequency shift, DeltanuA, determined by this method provides a more accurate measure of the degree of CT in ground and charge-separated states relative to other techniques which rely on the ground-state frequency shift alone. This approach enables determination of new experimental benchmarks to test the power of complimentary computational methods and provides a means to probe the degree of CT in transitions that either overlap strongly with other bands or possess low oscillator strength.

Authors
Rubtsov, IV; Kang, YK; Redmore, NP; Allen, RM; Zheng, J; Beratan, DN; Therien, MJ
MLA Citation
Rubtsov, IV, Kang, YK, Redmore, NP, Allen, RM, Zheng, J, Beratan, DN, and Therien, MJ. "The degree of charge transfer in ground and charge-separated states revealed by ultrafast visible pump/mid-IR probe spectroscopy." J Am Chem Soc 126.16 (April 28, 2004): 5022-5023.
PMID
15099057
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
126
Issue
16
Publish Date
2004
Start Page
5022
End Page
5023
DOI
10.1021/ja030674k

Interrogating conformationally dependent electron-transfer dynamics via ultrafast visible pump/IR probe spectroscopy.

We demonstrate for the first time the utility of time-resolved visible pump/mid-infrared (IR) probe spectroscopy to interrogate directly, and provide unique infomation regarding, conformationally dependent photoinduced ET dynamics and the subsequent structural evolution of the resulting charge-separated (CS) state. Exemplary polarized visible pump/IR probe experiments involving N-[5-(10,20-diphenylporphinato)zinc(II)]-N'(octyl)pyromellitic diimide (PZn-PI) and [5-[4'-(N-(N'-octyl)pyromellitic diimide)phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) (PZn()PI) show that it is possible to assess the mean PZn-to-PI interplanar torsional angle of electronically excited structural conformers that undergo ET within the sub-ps time domain for both of these donor-spacer-acceptor (D-Sp-A) systems. Further transient specroscopic experiments carried out on PZn()PI determine how this angle evolves with time. Because vibrational transition moments are often known and typically localized, this work underscores that polarized visible pump/IR probe spectroscopy defines a valuable tool to interrogate structrure in both electronically excited and CS states; this fact, coupled with the ultrafast time resolution and high senseitivity offered by this technique, make it ideally suited to probe a range of mechanistic issues relevant to charge-transfer reactions.

Authors
Rubtsov, IV; Redmore, NP; Hochstrasser, RM; Therien, MJ
MLA Citation
Rubtsov, IV, Redmore, NP, Hochstrasser, RM, and Therien, MJ. "Interrogating conformationally dependent electron-transfer dynamics via ultrafast visible pump/IR probe spectroscopy." J Am Chem Soc 126.9 (March 10, 2004): 2684-2685.
PMID
14995169
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
126
Issue
9
Publish Date
2004
Start Page
2684
End Page
2685
DOI
10.1021/ja0305499

Impact of electronic asymmetry on photoexcited triplet-state spin distributions in conjugated porphyrin oligomers probed via EPR spectroscopy

The photophysics of triplet excitons in a series of electronically asymmetric "push-pull" π-conjugated meso-to-meso ethyne-bridged (porphinato)metal oligomers, along with electronically symmetric analogues, were studied by X-band electron paramagnetic resonance (EPR) spectroscopy under continuous-wave (CW) optical pumping conditions in the 4-100 K temperature range. In all of the systems studied, the spatial extent of the triplet wave function, as inferred from the |D| zero-field splitting (ZFS) parameter, never exceeds the dimensions of a single porphyryl moiety and its meso-pendant ethynyl groups. The |D| values determined for an oligomeric series of these electronically asymmetric species that span one through four porphyryl units are respectively 0.0301, 0.0303, 0.0300, and 0.0301 cm -1, indicating a common triplet wave function spatial delocalization of approximately 0.4-0.45 nm. Electron spin-spin and spin-lattice relaxation times were determined over the 4-30 K temperature range using progressive microwave power saturation for benchmark, structurally related electronically symmetric conjugated porphyrin species which possessed either terminal electron-rich [4-dimethylammo(phenyl)] ethynyl or electron-poor [4-nitro(phenyl)]ethynyl substituents. The spin-lattice relaxation times obtained from these experiments reveal no significant scaling of this parameter with conjugation length, consistent with a S = 1 spin system that is confined to a single monomeric porphyrin unit and its pendent ethynyl substituents. These results are discussed within the global context of a broader body of experiments that have probed the extent of triplet exciton delocalization within a number of families of highly π-conjugated organic oligomers and polymers.

Authors
Angiolillo, PJ; Uyeda, HT; Duncan, TV; Therien, MJ
MLA Citation
Angiolillo, PJ, Uyeda, HT, Duncan, TV, and Therien, MJ. "Impact of electronic asymmetry on photoexcited triplet-state spin distributions in conjugated porphyrin oligomers probed via EPR spectroscopy." Journal of Physical Chemistry B 108.32 (2004): 11893-11903.
Source
scival
Published In
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical
Volume
108
Issue
32
Publish Date
2004
Start Page
11893
End Page
11903
DOI
10.1021/jp040032z

Visible and near-infrared excited-state dynamics of single-walled carbon nanotubes

Excited-state lifetimes of isolated single-walled semiconducting carbon nanotubes (SWNTs) have been measured for the first time; these excited states, observed over the 400- to 1800-nm spectral domain, possess lifetimes that range from several ps to more than 100 ps. Sub-ps to ps decay components are assigned to relaxation in SWNT bundles. Interrogation of the samples with different SWNT mean diameters further confirms the dependence of the excited-state lifetime on roll-up vector. The ratio of fast and slow decaying component contributions in the first van Hove band can be viewed as a measure of the bundle content.

Authors
Rubtsov, IV; Russo, RM; Albers, T; Deria, P; Luzzi, DE; Therien, MJ
MLA Citation
Rubtsov, IV, Russo, RM, Albers, T, Deria, P, Luzzi, DE, and Therien, MJ. "Visible and near-infrared excited-state dynamics of single-walled carbon nanotubes." Applied Physics A: Materials Science and Processing 79.7 (2004): 1747-1751.
Source
scival
Published In
Applied Physics A: Materials Science and Processing
Volume
79
Issue
7
Publish Date
2004
Start Page
1747
End Page
1751
DOI
10.1007/s00339-004-2894-5

Synthesis, electronic structure, and electron transfer dynamics of (Aryl)ethynyl-bridged donor-acceptor systems.

The ET dynamics of a series of donor-spacer-acceptor (D-Sp-A) systems featuring (porphinato)zinc(II), (aryl)ethynyl bridge, and arene diimide units were investigated by pump-probe transient absorption spectroscopy. Analysis of these data within the context of the Marcus-Levich-Jortner equation suggests that the pi-conjugated (aryl)ethynyl bridge plays an active role in the charge recombination (CR) reactions of these species by augmenting the extent of (porphinato)zinc(II) cation radical electronic delocalization; this increase in cation radical size decreases the reorganization energy associated with the CR reaction and thereby attenuates the extent to which the magnitudes of the CR rate constants are solvent dependent. The symmetries of porphyrin-localized HOMO and HOMO-1, the energy gap between these two orbitals, and D-A distance appear to play key roles in determining whether the (aryl)ethynyl bridge simply mediates electronic superexchange or functions as an integral component of the D and A units.

Authors
Redmore, NP; Rubtsov, IV; Therien, MJ
MLA Citation
Redmore, NP, Rubtsov, IV, and Therien, MJ. "Synthesis, electronic structure, and electron transfer dynamics of (Aryl)ethynyl-bridged donor-acceptor systems." J Am Chem Soc 125.29 (July 23, 2003): 8769-8778.
PMID
12862471
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
125
Issue
29
Publish Date
2003
Start Page
8769
End Page
8778
DOI
10.1021/ja021278p

Ultrafast singlet excited-state polarization in electronically asymmetric ethyne-bridged bis[(porphinato)zinc(II)] complexes.

The excited-state dynamics of two conjugated bis[(porphinato)zinc(II)] (bis[PZn]) species, bis[(5,5'-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethyne (DD) and [(5,-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5',-15'-ethynyl-10',20'-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne (DA), were studied by pump-probe transient absorption spectroscopy and hole burning techniques. Both of these meso-to-meso ethyne-bridged bis[PZn] compounds display intense near-infrared (NIR) transient S(1)-->S(n) absorptions and fast relaxation of their initially prepared, electronically excited Q states. Solvational and conformational relaxation play key roles in both DD and DA ground- and excited-state dynamics; in addition to these processes that drive spectral diffusion, electronically excited DA manifests a 3-fold diminution of S(1)-->S(0) oscillator strength on a 2-20 ps time scale. Both DD and DA display ground-state and time-dependent excited-state conformational heterogeneity; hole burning experiments show that this conformational heterogeneity is reflected largely by the extent of porphyrin-porphyrin conjugation, which varies as a function of the pigment-pigment dihedral angle distribution. While spectral diffusion can be seen for both compounds, rotational dynamics driving configurational averaging (tau approximately 30 ps), along with a small solvational contribution, account for essentially all of the spectral changes observed for electronically excited DD. For DA, supplementary relaxation processes play key roles in the excited-state dynamics. Two fast solvational components (0.27 and 1.7 ps) increase the DA excited-state dipole moment and reduce concomitantly the corresponding S(1)-->S(0) transition oscillator strength; these data show that these effects derive from a time-dependent change of the degree of DA S(1)-state polarization, which is stimulated by solvation and enhanced excited-state inner-sphere structural relaxation.

Authors
Rubtsov, IV; Susumu, K; Rubtsov, GI; Therien, MJ
MLA Citation
Rubtsov, IV, Susumu, K, Rubtsov, GI, and Therien, MJ. "Ultrafast singlet excited-state polarization in electronically asymmetric ethyne-bridged bis[(porphinato)zinc(II)] complexes." J Am Chem Soc 125.9 (March 5, 2003): 2687-2696.
PMID
12603156
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
125
Issue
9
Publish Date
2003
Start Page
2687
End Page
2696
DOI
10.1021/ja021157p

Near-infrared electroluminescent light-emitting devices based on ethyne-bridged porphyrin fluorophores

The ethyne-bridged porphyrin oligomers constitutes a highly promising new class of emissive dopants suitable for the fabrication of near infrared (NIR) polymer-based light-emitting diodes (LEDs). These fluorophores, synthesized from simple porphyrinic building blocks, are attractive as components of long-wavelength electroluminescence (EL) layers that consist of conjugated polymer/small molecule blends. Such experiments, coupled with potentiometric data, showed that in EL charge is efficiently trapped by the porphyrinic guests.

Authors
Ostrowski, JC; Susumu, K; Robinson, MR; Therien, MJ; Bazan, GC
MLA Citation
Ostrowski, JC, Susumu, K, Robinson, MR, Therien, MJ, and Bazan, GC. "Near-infrared electroluminescent light-emitting devices based on ethyne-bridged porphyrin fluorophores." Advanced Materials 15.15 (2003): 1296-1300.
Source
scival
Published In
Advanced Materials
Volume
15
Issue
15
Publish Date
2003
Start Page
1296
End Page
1300
DOI
10.1002/adma.200305228

The Effect of Electronic Structure on Molecular First Hyperpolarizabilities of Highly Conjugated (Polypyridyl)metal-(Porphinato)zinc(II) Chromophores

Electronic structural modifications of previously reported highly conjugated (polypyridyl)metal-(porphinato)zinc(II) NLO chromophores have been carried out. A primary focus of these modifications probes the role played by porphyrin macrocycle electronic structure in effecting large molecular hyperpolarizabilities. Porphyrin meso-aryl substituents were replaced with electron withdrawing perfluoroalkyl groups, effectively lowering the HOMO and LUMO energies of the porphyrin fragment orbitals by 0.35 eV. Extensive mixing of B, Q, and CT states of the component metal polypyridyl and porphyrinic building blocks coupled with head-to-tail transition dipole alignment of these low energy transitions give rise to substantial molecular hyperpolarizabilities. This work will be placed in the context of ongoing electrooptic experiments and efforts aimed at fabricating new materials from these supermolecular chromophoric species.

Authors
Miloradovic, IR; Zhao, Y; Wostyn, K; Asselberghs, I; Uyeda, HT; Persoons, A; Clays, K; Therien, MJ
MLA Citation
Miloradovic, IR, Zhao, Y, Wostyn, K, Asselberghs, I, Uyeda, HT, Persoons, A, Clays, K, and Therien, MJ. "The Effect of Electronic Structure on Molecular First Hyperpolarizabilities of Highly Conjugated (Polypyridyl)metal-(Porphinato)zinc(II) Chromophores." Proceedings of SPIE - The International Society for Optical Engineering 5212 (2003): 360-363.
Source
scival
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
5212
Publish Date
2003
Start Page
360
End Page
363

Utilizing Coupled-Oscillator Photophysics to Elaborate Chromophores with Exceptional Molecular Hyperpolarizabilities

The syntheses and electrooptic properties of a family of nonlinear optical chromophores are described. Typically, these species feature an ethyne-elaborated, highly polarizable porphyrinic component, and metal polypyridyl complexes that serve as integral donor and acceptor elements. The frequency dependence of the dynamic hyperpolarizability of a wide-range of these chromophores, that vary widely with respect to their electronic structure, was determined from hyper-Rayleigh light scattering (HRS) measurements carried out at fundamental incident irradiation wavelengths (λ inc) of 830, 1064, and 1300 nm. These data show that: (i) Coupled oscillator photophysics and metal-mediated cross-coupling can be exploited to elaborate high β λ supermolecules that exhibit significant excited-state electronic communication between their respective pigment building blocks; (ii) High-stability metal polypyridyl compounds constitute an attractive alternative to electron releasing dialkyl- and diarylamino groups, the most commonly used donor moieties in a wide-range of established NLO dyes, and long-recognized to be the moiety that often limits the thermal stability of such compounds; (iii) This design strategy clearly enables ready elaboration of extraordinarily large β λ chromophores at telecommunication-relevant wavelengths; and (iv) Multiple charge-transfer (CT) transitions within a single chromophore can be designed to have transition dipole moments of the same or opposite sign; because the sign of the resonance enhancement factor is frequency dependent, appropriate engineering of the relative contributions of these CT states at a given wavelength provides a new means to regulate the magnitude of dynamic hyperpolarizabilities.

Authors
Uyeda, HT; Miloradovic, I; Zhao, Y; Wostyn, K; Asselbergsh, I; Clays, K; Persoons, A; Therien, MJ
MLA Citation
Uyeda, HT, Miloradovic, I, Zhao, Y, Wostyn, K, Asselbergsh, I, Clays, K, Persoons, A, and Therien, MJ. "Utilizing Coupled-Oscillator Photophysics to Elaborate Chromophores with Exceptional Molecular Hyperpolarizabilities." Proceedings of SPIE - The International Society for Optical Engineering 5212 (2003): 117-121.
Source
scival
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
5212
Publish Date
2003
Start Page
117
End Page
121

Unusual frequency dispersion effects of the nonlinear optical response in highly conjugated (polypyridyl)metal-(porphinato)zinc(II) chromophores.

The syntheses and electrooptic properties of a new family of nonlinear optical chromophores are reported. These species feature an ethyne-elaborated, highly polarizable porphyrinic component and metal polypyridyl complexes that serve as integral donor and acceptor elements. Examples of this structural motif include ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)(2+) bis-hexafluorophosphate (Ru-PZn); osmium(II) [5-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2''-terpyridine)(2+) bis-hexafluorophosphate (Os-PZn); ruthenium(II) [5-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-15-(4'-nitrophenyl)ethynyl-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phen-yl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)(2+) bis-hexafluorophosphate (Ru-PZn-A); osmium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))-15-(4'-nitrophenyl)ethynyl-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2' '-terpyridine)(2+) bis-hexafluorophosphate (Os-PZn-A); and ruthenium(II) [5-(4'-ethynyl-(2,2';6',2' '-terpyridinyl))osmium(II)-15-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-10,20-bis (2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-bis(2,2';6',2''-terpyridine)(4+) tetrakis-hexafluorophosphate (Ru-PZn-Os). The frequency dependence of the dynamic hyperpolarizability of these compounds was determined from hyperRayleigh light scattering (HRS) measurements carried out at fundamental incident irradiation wavelengths (lambda(inc)) of 800, 1064, and 1300 nm. These data show that (i) coupled oscillator photophysics and metal-mediated cross-coupling can be exploited to elaborate high beta(0) supermolecules that exhibit significant excited-state electronic communication between their respective pigment building blocks; (ii) high-stability metal polypyridyl compounds constitute an attractive alternative to electron releasing dialkyl- and diarylamino groups, the most commonly used donor moieties in a wide range of established nonlinear optical dyes; (iii) this design strategy enables ready elaboration of chromophores having extraordinarily large dynamic hyperpolarizabilities (beta(lambda) values) at telecommunication relevant wavelengths; and (iv) porphyrin B- and Q-state-derived static hyperpolarizabilities (beta(0) values) can be designed to have the same or opposite sign in these species, thus providing a new means to regulate the magnitude of lambda(inc)-specific dynamic hyperpolarizabilities.

Authors
Uyeda, HT; Zhao, Y; Wostyn, K; Asselberghs, I; Clays, K; Persoons, A; Therien, MJ
MLA Citation
Uyeda, HT, Zhao, Y, Wostyn, K, Asselberghs, I, Clays, K, Persoons, A, and Therien, MJ. "Unusual frequency dispersion effects of the nonlinear optical response in highly conjugated (polypyridyl)metal-(porphinato)zinc(II) chromophores." J Am Chem Soc 124.46 (November 20, 2002): 13806-13813.
PMID
12431110
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
124
Issue
46
Publish Date
2002
Start Page
13806
End Page
13813

Decoupling optical and potentiometric band gaps in pi-conjugated materials.

Syntheses, optical spectroscopy, potentiometric studies, and electronic structural calculations are reported for two classes of conjugated (porphinato)metal oligomers that feature a meso-to-meso ethyne-bridged linkage topology. One set of these systems, bis[(5,5'-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethyne (DD), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-10' ',20' '-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDDDD), constitute highly soluble analogues of previously studied examples of this structural motif having simple 10,20-diaryl substituents, while a corresponding set of conjugated oligomers, [(5-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5'-15'-ethynyl-10',20'-bis[10,20-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne (DA), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis(heptafluoropropyl)porphinato]zinc(II) (DAD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-(10' ',20' '-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DADAD), features alternating electron-rich and electron-poor (porphinato)zinc(II) units. Electrooptic and computational data for these species demonstrate that it is possible to engineer conjugated oligomeric structures that possess highly delocalized singlet (S1) excited states yet manifest apparent one-electron oxidation and reduction potentials (E1/20/+ and E1/2-/0 values) that are essentially invariant with respect to those elucidated for their constituent monomeric precursors.

Authors
Susumu, K; Therien, MJ
MLA Citation
Susumu, K, and Therien, MJ. "Decoupling optical and potentiometric band gaps in pi-conjugated materials." J Am Chem Soc 124.29 (July 24, 2002): 8550-8552.
PMID
12121095
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
124
Issue
29
Publish Date
2002
Start Page
8550
End Page
8552

Distance dependence of electron transfer in rigid, cofacially compressed, pi-stacked porphyrin-bridge-quinone systems.

The electron-transfer (ET) dynamics of a series of unusually rigid pi-stacked porphyrin-quinone (P-Q) systems, in which sub-van der Waals interplanar distances separate juxtaposed porphyryl, aromatic bridge, and quinonyl components of these assemblies, are reported. The photoinduced charge separation (CS) and thermal charge recombination (CR) ET reactions of [5-[8'-(2'',5''-benzoquinonyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (1a-Zn), [5-[8'-(4''-[8'"-(2'"',5'"'-benzoquinonyl)-1'"-naphthyl]-1''-phenyl)-1'-naphthyl]-10,20-diphenylporphinato]zinc(II) (2a-Zn), and [5-(8'-[4''-(8'"-[4'"'-(8'"-[2'"',5'"'-benzoquinonyl]-1'"-naphthyl)-1'"'-phenyl]-1'"-naphthyl)-1''-phenyl]-1'-naphthyl)-10,20-diphenylporphinato]zinc(II) (3a-Zn) in CH(2)Cl(2) were investigated by pump-probe transient absorption spectroscopy. Analyses of these data show that the phenomenological ET distance dependence (beta) for both the CS and CR reactions in these systems is soft (beta(CS) = 0.43 A(-1); beta(CR) = 0.35 +/- 0.16 A(-1)). This work demonstrates that simple aromatic building blocks such as benzene, which are characterized by highly stabilized filled molecular orbitals and large HOMO-LUMO gaps, can provide substantial D-A electronic coupling when organized within a pi-stacked structural motif that features a modest degree of arene-arene interplanar compression.

Authors
Kang, YK; Rubtsov, IV; Iovine, PM; Chen, J; Therien, MJ
MLA Citation
Kang, YK, Rubtsov, IV, Iovine, PM, Chen, J, and Therien, MJ. "Distance dependence of electron transfer in rigid, cofacially compressed, pi-stacked porphyrin-bridge-quinone systems." J Am Chem Soc 124.28 (July 17, 2002): 8275-8279.
PMID
12105906
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
124
Issue
28
Publish Date
2002
Start Page
8275
End Page
8279

Extreme electronic modulation of the cofacial porphyrin structural motif.

The synthesis, electrochemistry, and optical spectroscopy of an extensive series of cofacial bis[(porphinato)zinc(II)] compounds are reported. These species were synthesized using sequential palladium-catalyzed cross-coupling and cobalt-mediated [2+2+2] cycloaddition reactions. This modular methodology enables facile control of the nature of macrocycle-to-macrocycle connectivity and allows unprecedented modulation of the redox properties of face-to-face porphyrin species. We report the synthesis of 5,6-bis[(5',5''-10',20'-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1), 5,6-bis[(2'-5',10',15',20'-tetraphenylporphinato)zinc(II)]indane (2), 5-([2'-5',10',15',20'-tetraphenylporphinato]zinc(II))-6-[(5"-10'',20''-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (3), 5-([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(5' '-10' ',20' '-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (4), 5-(2'-5',10',15',20'-[tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(2''-5'',10'',15'',20''-tetraphenylporphinato)zinc(II)]indane (5), 5,6-bis([2'-5',15'-diphenyl-10',20'-(trifluoromethyl)porphinato]zinc(II))indane (6), and 5,6-bis([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))indane (7); 4-7 define the first examples of cofacial bis[(porphinato)metal] compounds in which sigma-electron-withdrawing perfluoroalkyl groups serve as macrocycle substituents, while 2, 6, and 7 constitute the first such structures that possess a beta-to-beta linkage topology. Cyclic voltammetric studies show that the electrochemically determined HOMO and LUMO energy levels of these cofacial bis(porphinato) complexes can be lowered by 780 and 945 mV, respectively, relative to the archetypal members of this class of compounds; importantly, these orbital energy levels can be modulated over well-defined increments throughout these wide potentiometric domains. Analyses of these cofacial bis[(porphinato)metal] potentiometric data, in terms of the absolute and relative frontier orbital energies of their constituent [porphinato]zinc(II) building blocks, as well as the nature of macrocycle-to-macrocycle connectivity, provide predictive electronic structural models that rationalize the redox behavior of these species.

Authors
Fletcher, JT; Therien, MJ
MLA Citation
Fletcher, JT, and Therien, MJ. "Extreme electronic modulation of the cofacial porphyrin structural motif." J Am Chem Soc 124.16 (April 24, 2002): 4298-4311.
PMID
11960459
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
124
Issue
16
Publish Date
2002
Start Page
4298
End Page
4311

Synthesis, excited-state dynamics, and reactivity of a directly-linked pyromellitimide-(porphinato)zinc(II) complex.

N-[5-(10,20-Diphenylporphinato)zinc(II)]-N'-(octyl)pyromellitic diimide (PZn-PI), a meso-pyromellitimide-substituted (porphinato)zinc(II) compound, has been fabricated from the reaction of (5-amino-10,20-diphenylporphinato)zinc(II) with pyromellitic dianhydride in the presence of octylamine. Interrogation of the photoinduced charge separation (CS) and thermal charge recombination (CR) electron-transfer (ET) dynamics for PZn-PI in CH(2)Cl(2) via pump-probe transient absorption spectroscopic methods shows that tau(CS) and tau(CR) are 770 and 5200 fs, respectively. These ET dynamics differ from those elucidated previously for closely related 5-quinonyl-substituted (porphinato)metal compounds, and derive from the fact that the low-lying excited states for PZn-PI are porphyrin-localized, possessing little charge-transfer character. The synthesis of N-(5-[15-(2-(triisopropylsilyl)ethynyl)-10,20-diphenylporphinato]zinc(II))-N'-(octyl)pyromellitic diimide demonstrates that PZn-PI can be halogenated at its 15-meso-position and used subsequently as a substrate in metal-catalyzed cross-coupling reactions; the reactivity of PZn-PI is unusual with respect to many directly linked donor-acceptor compounds in that it is stable to these oxidizing and reducing reaction conditions.

Authors
Redmore, NP; Rubtsov, IV; Therien, MJ
MLA Citation
Redmore, NP, Rubtsov, IV, and Therien, MJ. "Synthesis, excited-state dynamics, and reactivity of a directly-linked pyromellitimide-(porphinato)zinc(II) complex." Inorg Chem 41.3 (February 11, 2002): 566-570.
PMID
11825084
Source
pubmed
Published In
Inorganic Chemistry
Volume
41
Issue
3
Publish Date
2002
Start Page
566
End Page
570

Strongly coupled porphyrin arrays featuring both pi-cofacial and linear-pi-conjugative interactions.

A combination of metal-catalyzed cross-coupling and metal-templated cycloaddition reactions have been utilized to establish multiporphyrin compounds 5-(5'-[15',15' '-bis(10' ',20' '-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)-6-[(5' "-10' ",20' "-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1) and 5,6-bis(5'-15',15' '-bis[(10',20'-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)indane (2). Compounds 1 and 2 feature a covalently bridged cofacial bis(porphinato)metal core; ethyne bridging moieties conjugate directly one and two respective peripheral (porphinato)zinc(II) substituents to the macrocyclic framework of their corresponding face-to-face porphyrin units. Optical spectroscopy and electrochemical studies demonstrate substantive electronic interactions between the porphyrin subunits of these compounds. Notably, structural and (1)H NMR analyses verify that 1 and 2 possess open conformations necessary for binding small molecules within their respective cofacial (porphinato)metal cores.

Authors
Fletcher, JT; Therien, MJ
MLA Citation
Fletcher, JT, and Therien, MJ. "Strongly coupled porphyrin arrays featuring both pi-cofacial and linear-pi-conjugative interactions." Inorg Chem 41.2 (January 28, 2002): 331-341.
PMID
11800622
Source
pubmed
Published In
Inorganic Chemistry
Volume
41
Issue
2
Publish Date
2002
Start Page
331
End Page
341

Arylethynyl-derivatized porphyrin chromophores featuring potent electron donors and acceptors for nonlinear optical applications

Authors
Zhang, TG; Therien, MJ
MLA Citation
Zhang, TG, and Therien, MJ. "Arylethynyl-derivatized porphyrin chromophores featuring potent electron donors and acceptors for nonlinear optical applications." American Chemical Society, Polymer Preprints, Division of Polymer Chemistry 43.2 (January 1, 2002): 570-571.
Source
scopus
Published In
Papers presented at the ... meeting. American Chemical Society. Division of Polymer Chemistry
Volume
43
Issue
2
Publish Date
2002
Start Page
570
End Page
571

Highly conjugated porphyrin-based chromophore systems with unusual electrooptic properties

Authors
Uyeda, HT; Zhang, Y; Clays, K; Persoons, A; Therien, MJ
MLA Citation
Uyeda, HT, Zhang, Y, Clays, K, Persoons, A, and Therien, MJ. "Highly conjugated porphyrin-based chromophore systems with unusual electrooptic properties." American Chemical Society, Polymer Preprints, Division of Polymer Chemistry 43.2 (January 1, 2002): 520-521.
Source
scopus
Published In
Papers presented at the ... meeting. American Chemical Society. Division of Polymer Chemistry
Volume
43
Issue
2
Publish Date
2002
Start Page
520
End Page
521

High-resolution structure and conformational dynamics of rigid, cofacially aligned porphyrin-bridge-quinone systems as determined by NMR spectroscopy and ab initio simulated annealing calculations.

The high-resolution solution structure and dynamics of a cofacially aligned porphyrin--phenylene--quinone compound have been determined using (1)H NMR spectroscopy and simulated annealing calculations. Members of this class of pi-stacked assemblies feature a 1,8-naphthyl pillaring motif that enforces sub van der Waals interplanar separations between juxtaposed porphyryl, aromatic bridge, and quinonyl components of the donor--spacer--acceptor compound; this structural motif gives rise to a comprehensive set of structurally significant NOE signatures that can be used as constraints in quantitative structural calculations. Examination of such data using ab initio simulated annealing analytical methods shows that 5-[8'-(4' '-[8' "-(2' " ',5' "-benzoquinonyl)-1' "-naphthyl]-1' '-phenyl)-1'-naphthyl]-10,20-diphenylporphyrin displays an unusual degree of conformational homogeneity in the condensed phase, and represents a rare example where such an analysis determines unequivocally a single unique structure in solution.

Authors
Iovine, PM; Veglia, G; Furst, G; Therien, MJ
MLA Citation
Iovine, PM, Veglia, G, Furst, G, and Therien, MJ. "High-resolution structure and conformational dynamics of rigid, cofacially aligned porphyrin-bridge-quinone systems as determined by NMR spectroscopy and ab initio simulated annealing calculations." J Am Chem Soc 123.24 (June 20, 2001): 5668-5679.
PMID
11403598
Source
pubmed
Published In
Journal of the American Chemical Society
Volume
123
Issue
24
Publish Date
2001
Start Page
5668
End Page
5679

Trends in triplet excitation delocalization in highly conjugated (porphinato)zinc(II) arrays probed by EPR spectroscopy

The lowest photoexcited metastable triplet state of a family of highly conjugated (porphinato)zinc(II) arrays in which ethyne, butadiyne, and octatetrayne units bridge the macrocycle carbon frameworks were studied by EPR spectroscopy at low temperature in solution. One series of meso-to-meso ethyne-bridged (porphinato)zinc(II) structures probes how the length of the conjugated bridge separating two (porphinato)zinc(II) units effects the nature of the triplet excited state, while a second set of compounds assesses the impact that oligomer size has upon triplet state spin distribution and orientation. Although the magnitude of the EPR |D| values decrease with increasing number of porphyrin units, the data do not suggest that the lowest triplet excitation extends beyond a single porphyrin unit. With augmented conjugation, these systems show a progressive oblate-to-prolate spin distribution transition that causes the direction of largest dipolar interaction to align along a vector defined by the highly conjugated axes of these molecules. Temperature EPR line shape studies of these Zn porphyrin arrays reveal that (1) the triplet spectrum evinces no changes up to 100 K, indicating the absence of Jahn-Teller-induced dynamics, and (2) the EPR spectra of the triplet states for all dimers, trimers, and pentamers exhibit electron spin polarization up to temperatures surpassing 100 K, suggesting spin lattice relaxation times that do not decrease significantly with temperature.

Authors
Angiolillo, PJ; Susumu, K; Uyeda, HT; Lin, VS-Y; Shediac, R; Therien, MJ
MLA Citation
Angiolillo, PJ, Susumu, K, Uyeda, HT, Lin, VS-Y, Shediac, R, and Therien, MJ. "Trends in triplet excitation delocalization in highly conjugated (porphinato)zinc(II) arrays probed by EPR spectroscopy." Synthetic Metals 116.1-3 (2001): 247-253.
Source
scival
Published In
Synthetic Metals
Volume
116
Issue
1-3
Publish Date
2001
Start Page
247
End Page
253
DOI
10.1016/S0379-6779(00)00461-6

Mechanistic studies of (porphinato)iron-catalyzed isobutane oxidation. Comparative studies of three classes of electron-deficient porphyrin catalysts.

We report herein a comprehensive study of (porphinato)iron [PFe]-catalyzed isobutane oxidation in which molecular oxygen is utilized as the sole oxidant; these catalytic reactions were carried out and monitored in both autoclave reactors and sapphire NMR tubes. In situ 19F and 13C NMR experiments, coupled with GC analyses and optical spectra obtained from the autoclave reactions have enabled the identification of the predominant porphyrinic species present during PFe-catalyzed oxidation of isobutane. Electron-deficient PFe catalysts based on 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin [(C6F5)4PH2], 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl) porphyrin [Br8(C6F5)4PH2], and 5,10,15,20-tetrakis(heptafluoropropyl) porphyrin [(C3F7)4PH2] macrocycles were examined. The nature and distribution of hydrocarbon oxidation products show that an autoxidation reaction pathway dominates the reaction kinetics, consistent with a radical chain process. For each catalytic system examined, PFeII species were shown not to be stable under moderate O2 pressure at 80 degrees C; in every case, the PFeII catalyst precursor was converted quantitatively to high-spin PFeIII complexes prior to the observation of any hydrocarbon oxidation products. Once catalytic isobutane oxidation is initiated, all reactions are marked by concomitant decomposition of the porphyrin-based catalyst. In situ 17O NMR spectroscopic studies confirm the incorporation of 17O from labeled water into the oxidation products, implicating the involvement of PFe-OH in the catalytic cycle. Importantly, Br8(C6F5)4PFe-based catalysts, which lack macrocycle C-H bonds, do not exhibit augmented stability with respect to analogous catalysts based on (C6F5)4PFe and (C3F7)4PFe species. The data presented are consistent with a hydrocarbon oxidation process in which PFe complexes play dual roles of radical chain initiator, and the species responsible for the catalytic decomposition of organic peroxides. This modified Haber-Weiss reaction scheme provides for the decomposition of tert-butyl hydroperoxide intermediates via reaction with PFe-OH complexes; the PFeIII species responsible for hydroperoxide decomposition are regenerated by reaction of PFeII with dioxygen under these experimental conditions.

Authors
Moore, KT; Horváth, IT; Therien, MJ
MLA Citation
Moore, KT, Horváth, IT, and Therien, MJ. "Mechanistic studies of (porphinato)iron-catalyzed isobutane oxidation. Comparative studies of three classes of electron-deficient porphyrin catalysts." Inorg Chem 39.15 (July 24, 2000): 3125-3139.
PMID
11196847
Source
pubmed
Published In
Inorganic Chemistry
Volume
39
Issue
15
Publish Date
2000
Start Page
3125
End Page
3139

Syntheses and1H NMR spectroscopy of rigid, cofacially aligned, porphyrin-bridge-quinone systems in which the interplanar separations between the porphyrin, aromatic bridge, and quinone are less than the sum of their respective van der waals radii

Unusually rigid π-stacked porphyrin-spacer-quinone systems have been synthesized using an approach that enables extensive control over the nature of electronic interactions between donor, aromatic spacer, and acceptor. This new class of porphyrin-based structures is distinct from related assemblies designed to probe electronic interactions between cofacial π-stacked, aromatics: the donor (D), spacer (Sp), and acceptor (A) components of the assembly are held fixed at sub van der Waals contact distances, restricting severely the range of dynamical processes that modulate typically the magnitude of inter-ring separation and the extent of the lateral shift between juxtaposed aromatic units in the condensed phase. NMR spectroscopic studies demonstrate that these structures manifest disparate shielding environments which distribute uniformly the aromatic 'H resonances for these diamagnetic D-Sp-A compounds over spectral windows that exceed 9.0 ppm. © 2000 American Chemical Society.

Authors
Iovine, PM; Kellett, MA; Redmore, NP; Therien, MJ
MLA Citation
Iovine, PM, Kellett, MA, Redmore, NP, and Therien, MJ. "Syntheses and1H NMR spectroscopy of rigid, cofacially aligned, porphyrin-bridge-quinone systems in which the interplanar separations between the porphyrin, aromatic bridge, and quinone are less than the sum of their respective van der waals radii." Journal of the American Chemical Society 122.36 (2000): 8717-8727.
Source
scival
Published In
Journal of the American Chemical Society
Volume
122
Issue
36
Publish Date
2000
Start Page
8717
End Page
8727

Transition-metal-mediated [2 + 2 + 2] cycloaddition reactions with ethyne-containing porphyrin templates: New routes to cofacial porphyrin structures and facially-functionalized (porphinato)metal species

Authors
Fletcher, JT; Therien, MJ
MLA Citation
Fletcher, JT, and Therien, MJ. "Transition-metal-mediated [2 + 2 + 2] cycloaddition reactions with ethyne-containing porphyrin templates: New routes to cofacial porphyrin structures and facially-functionalized (porphinato)metal species." Journal of the American Chemical Society 122.49 (2000): 12393-12394.
Source
scival
Published In
Journal of the American Chemical Society
Volume
122
Issue
49
Publish Date
2000
Start Page
12393
End Page
12394
DOI
10.1021/ja0001557

Singlet and triplet excited states of emissive, conjugated bis(porphyrin) compounds probed by optical and EPR spectroscopic methods

The nature of the singlet and triplet excited states of a series of meso-to-meso ethyne-linked bis(porphyrin) compounds was probed by electronic absorption, polarized pump - probe fluorescence, electron paramagnetic resonance (EPR), electroabsorption (Stark), and transient triplet - triplet absorption spectroscopic methods, Pump - probe fluorescence anisotropy experiments show that the presence of meso-ethynyl substituents drives a reorientation of orthogonal x- and y-polarized singlet excited states in the macrocycle frame of reference with respect to that evinced for conventional free-base porphyrin chromophores. Analogous experiments in conjugated bis(porphyrin) species bis[(5,5',-10,20-bis[3,5-(di-tert -butyl)phenyl]porphinato)zinc(II)]ethyne, 5-[10,20-bis[3,5-(di-tert-butyl)phenyl]porphinato)zinc(II)]-5'- [10',20'-bis[3,5-(di-tert-butyl)phenyl]porphyryl]ethyne, and bis[5,5',-10,20-bis[3,5-(di-tert-butyl)phenyl]porphyryl]ethyne demonstrate substantial energetic splittings of the x- and y-polarized S1 states. The magnitude of this energetic gap results in the complete suppression of population exchange between excited states having orthogonal polarizations on the time scale of these measurements, and gives rise to singly degenerate emitting states polarized exclusively along the axis defined by the ethyne moiety. Stark spectroscopic experiments show that the electronically symmetric meso-to-meso ethyne-bridged bis[(porphinato)zinc(II)] complex exhibits changes in dipole moment with respect to the ground state in its respective x-polarized S2 and S1 states. The EPR spectra of the low-lying photoexcited triplet excited states of these conjugated bis(porphyrin) compounds and their ethyne-substituted porphyrinic building blocks show an evolution in the |D| and |E| ZFS parameters with augmented conjugation consistent with a progressing oblate-to-prolate spin transition that causes the direction of largest dipolar interaction to align along the vector defined by the conjugated ethyne moiety. Conjugated arrays based on meso-ethyne elaborated porphyrin and (porphinato)zinc(II) precursors thus constitute an unusual class of oligomeric porphyrin species in that once a threshold level of conjugation is reached, the optical and magnetic principal axis systems become coincident.

Authors
Shediac, R; Gray, MHB; Uyeda, HT; Johnson, RC; Hupp, JT; Angiolillo, PJ; Therien, MJ
MLA Citation
Shediac, R, Gray, MHB, Uyeda, HT, Johnson, RC, Hupp, JT, Angiolillo, PJ, and Therien, MJ. "Singlet and triplet excited states of emissive, conjugated bis(porphyrin) compounds probed by optical and EPR spectroscopic methods." Journal of the American Chemical Society 122.29 (2000): 7017-7033.
Source
scival
Published In
Journal of the American Chemical Society
Volume
122
Issue
29
Publish Date
2000
Start Page
7017
End Page
7033
DOI
10.1021/ja9939587

Multilayer Langmuir-Blodgett porphyrin films for second-order non-linear optics

The Langmuir-Blodgett-Kuhn (LBK) room-temperature method for making non-linear optical (NLO) polymer films is investigated. A Mach-Zender interferometer by the LBK method is made for optical modulation, demonstrating that useful devices are made from relatively thick, room-temperature-deposited NLO polymer films. The LBK method is convenient for fabricating films from large, temperature-sensitive, even ion-containing chromophores that is difficult to align by electric-field poling. At high temperatures, the electric conductivity of the film is so high that the field across the film is not adequate to give a high degree of polar order.

Authors
Kolega, RR; Lindsay, GA; Roberts, MJ; Uyeda, HT; Therien, M; Herman, WN
MLA Citation
Kolega, RR, Lindsay, GA, Roberts, MJ, Uyeda, HT, Therien, M, and Herman, WN. "Multilayer Langmuir-Blodgett porphyrin films for second-order non-linear optics." American Chemical Society, Polymer Preprints, Division of Polymer Chemistry 41.1 (2000): 863-864.
Source
scival
Published In
American Chemical Society, Polymer Preprints, Division of Polymer Chemistry
Volume
41
Issue
1
Publish Date
2000
Start Page
863
End Page
864

Multilayer χ(2) films from porphyrin chromophores by LBK processing

Electrooptic films based on a new class of porphyrin chromophores with exceptionally large molecular first hyperpolarizabilities are being developed. These chromophores feature donor and acceptor groups linked to the porphyrin macrocycle at the 5- and 15-meso positions through intervening ethynyl moieties. We report herein preliminary results that describe the ambient temperature assembly of ordered, electrooptic films using the Langmuir-Blodgett-Kuhn (LBK) method. The facile formation of such films was made possible by the preparation of amphiphilic chromophores containing hydrophobic aliphatic substituents to enhance the polar alignment at the air-water interface. Second harmonic generation and UV-Vis absorption were used to characterize the films as a function of the number of layers deposited. Polar films containing up to 10 layers were made by simple Y-type homolayer deposition, and up to six layers by the Y-type heterolayer method in which the porphyrin layers were interleaved with poly(t-butyl methacrylate). The polar order in these films relaxed exponentially (50% at room temperature after 3 weeks). Ionic structures are recommended for improved stability.

Authors
Lindsay, GA; Kolega, RR; Roberts, MJ; Uyeda, HT; Therien, M; Herman, WN
MLA Citation
Lindsay, GA, Kolega, RR, Roberts, MJ, Uyeda, HT, Therien, M, and Herman, WN. "Multilayer χ(2) films from porphyrin chromophores by LBK processing." Proceedings of SPIE - The International Society for Optical Engineering 3796 (1999): 299-307.
Source
scival
Published In
Proceedings of SPIE - The International Society for Optical Engineering
Volume
3796
Publish Date
1999
Start Page
299
End Page
307

Syntheses, NMR and EPR spectroscopy, electrochemical properties, and structural studies of [5,10,15,20- tetrakis(perfluoroalkyl)porphinato]iron(II) and -iron(III) complexes

Syntheses, structural studies, electrochemistry, and spectroscopy of a number of [5,10,15,20-tetrakis(heptafluoropropyl)porphinato]iron derivatives are presented. The X-ray crystal structure of 5,10,15,20- tetrakis(heptafluoropropyl)porphinato]iron(II)·(pyridine)2 exhibits a substantial S4 distortion of the porphyrin macrocycle, with the meso-carbon atoms displaced more than 0.6 Å above and below the porphyrin mean plane defined by the four central nitrogen atoms; the most notable aspect of this ferrous porphyrin structure is the fact that it exhibits metrical features commonly manifested in crystallographically characterized ferric porphyrin complexes. X-ray data are as follows: P21/n with a = 12.772(1) Å, b = 18.895(2) Å, c = 19.756(2) Å, β = 99.960(6)°, V = 4695.7(8) Å3, Z = 4, and d(calc) = 1.689 g/cm3. 19F NMR spectroscopy confirms the sensitivity of the 19F nucleus as a probe of macrocycle aromaticity and electronic structure, while 1H NMR spectroscopic studies show large isotropic shifts for the β-protons of the (porphinato)iron(III) chloride derivative (δ = 101.5 and 86.4 ppm). Electrochemical data obtained from cyclic voltammetric and spectroelectrochemical experiments reveal that the E(1/2) value for the Fe(II/III) redox couple for 5,10,15,20- tetrakis(heptafluoropropyl)porphinato]iron·(pyridine)2 is shifted by 550 mV relative to that observed for the corresponding (porphinato)iron(III) chloride complex. The cathodic electrochemistry of [5,10,15,20- tetrakis(heptafuoropropyl)porphinato]iron·(pyridine)2 is also unusual in that the first one-electron reduction of this complex produces a largely macrocycle-localized radical anion. EPR spectroscopic data shows that 5,10,15,20-tetrakis(heptafluoropropyl)porphinato]iron(III)·(pyridine)2 manifests a pure axial spectrum (Δ/λ = -26.4; Σg2 = 12.53) congruent with a (d(xz),d(yz))4(d(xy))1 electronic ground state. The extraordinary structural, potentiometric, and spectroscopic properties of these (porphinato)iron species arise from substantially reduced metal-centered electron density effected by the macrocycle's non-π-conjugating, σ- electron-withdrawing meso-perfluoroalkyl substituents.

Authors
Moore, KT; Fletcher, JT; Therien, MJ
MLA Citation
Moore, KT, Fletcher, JT, and Therien, MJ. "Syntheses, NMR and EPR spectroscopy, electrochemical properties, and structural studies of [5,10,15,20- tetrakis(perfluoroalkyl)porphinato]iron(II) and -iron(III) complexes." Journal of the American Chemical Society 121.22 (1999): 5196-5209.
Source
scival
Published In
Journal of the American Chemical Society
Volume
121
Issue
22
Publish Date
1999
Start Page
5196
End Page
5209
DOI
10.1021/ja9816741

Suzuki porphyrins: New synthons for the fabrication of porphyrin- containing supramolecular assemblies [6]

Authors
Hyslop, AG; Kellett, MA; Iovine, PM; Therien, MJ
MLA Citation
Hyslop, AG, Kellett, MA, Iovine, PM, and Therien, MJ. "Suzuki porphyrins: New synthons for the fabrication of porphyrin- containing supramolecular assemblies [6]." Journal of the American Chemical Society 120.48 (1998): 12676-12677.
Source
scival
Published In
Journal of the American Chemical Society
Volume
120
Issue
48
Publish Date
1998
Start Page
12676
End Page
12677
DOI
10.1021/ja982410h

Synthesis of porphyrin-spacer-quinone compounds via metal-mediated cross-coupling: New systems for probing the relative magnitudes of axial and equatorial electronic coupling at the porphyrin macrocycle in thermal and photoactivated electron transfer reactions

Two classes of (porphinato)zinc(II)-spacer-quinone electron transfer compounds were fabricated through metal-mediated cross-coupling reactions using appropriately derivatized porphyrin, dimethoxybenzene and phenylene spacer moieties. The syntheses of these electron transfer model systems utilized either a (2,5-dimethoxyphenyl)boronic acid or a boronic acid derivative of a 2,5-dimethoxyphenyl-substituted spacer compound which was subsequently coupled to either [5-(4′-bromophenyl)-10,15,20-triphenylporphinato]zinc(II) or 4-bromopyridine; the former species define compounds in which to probe the magnitude of electronic coupling between the meso-appended spacer moiety and the porphyrin carbon framework, while the latter constitute acceptor-modified, rigid axial ligands, that will facilitate a comparison of this coupling to that enabled by the zinc (II)-coordinated pyridyl moiety orthogonal to the porphyrin πT system. These compounds further underscore the utility of combining the modular syntheses of donor, acceptor and spacer molecules with Pd-catalyzed carbon-carbon bond forming reactions to elaborate porphyrin-based donor-spacer-acceptor systems. © 1998 Elsevier Science S.A. All rights reserved.

Authors
Hyslop, AG; Therien, MJ
MLA Citation
Hyslop, AG, and Therien, MJ. "Synthesis of porphyrin-spacer-quinone compounds via metal-mediated cross-coupling: New systems for probing the relative magnitudes of axial and equatorial electronic coupling at the porphyrin macrocycle in thermal and photoactivated electron transfer reactions." Inorganica Chimica Acta 275-276 (1998): 427-434.
Source
scival
Published In
Inorganica Chimica Acta
Volume
275-276
Publish Date
1998
Start Page
427
End Page
434

Ultrafast dynamics of highly conjugated porphyrin arrays

The photophysical properties of a series of ethynyl-bridged (porphinato)zinc(II) oligomers have been investigated over the femtosecond and picosecond time scales using ultrafast magic angle and polarized pump- probe spectroscopy. Bis[(2,2',-5,10,15,20- tetraphenylporphinato)zinc(II)]ethyne, bis[(5,5',-10,20- diphenylporphinato)zinc(II)]ethyne, and 5,15-bis{[(5',-10',20'- diphenylporphinato)zinc(II)]ethynyl}[10,20-diphenylporphinato]zinc(II) exhibit rapid (≤ 150 fs) formation of the emitting state following Soret photoexcitation, nearly an order of magnitude faster than the ~1 ps S2 ~ S1 internal conversion observed for a monomeric (porphinato)zinc(II) complex that bears an ethyne moiety fused directly to its macrocycle carbon framework [(5-trimethylsilylethynyl-10,20-diphenylporphinato)zinc(II)]. The femtosecond and picosecond dynamics are strongly influenced by the porphyrin-to-porphyrin linkage topology: bis[(2,2',-5,10,15,20-tetraphenylporphinato)- zinc(II)]ethyne, in which a β-to-β ethyne bridge links the two (porphinato)zinc(II) moieties, maintains the x-y degeneracy of the emitting state, the dynamics of which are consistent with energy equilibration within a weakly coupled porphyrin pair. In contrast, systems which feature a meso- to-meso ethynyl-bridged linkage topology between (porphinato)zinc(II) units exhibit properties consistent with significant inter-ring conjugation and loss of x-y degeneracy for the (π, π*) excited states. Collectively, the steady-state and time-resolved results for these meso-to-meso bridged systems suggest some degree of conformational heterogeneity for the ground state structures in solution, which differ with respect to the degree of conjugation of porphyrin rings; these conformers interconvert an the S1 excited state on a ~30 ps time scale to produce a conformationally uniform, coplanar emitting state.

Authors
Kumble, R; Palese, S; Lin, VS-Y; Therien, MJ; Hochstrasser, RM
MLA Citation
Kumble, R, Palese, S, Lin, VS-Y, Therien, MJ, and Hochstrasser, RM. "Ultrafast dynamics of highly conjugated porphyrin arrays." Journal of the American Chemical Society 120.44 (1998): 11489-11498.
Source
scival
Published In
Journal of the American Chemical Society
Volume
120
Issue
44
Publish Date
1998
Start Page
11489
End Page
11498
DOI
10.1021/ja981811u

Electronic stark effect studies of a porphyrin-based push-pull chromophore displaying a large first hyperpolarizability: State-specific contributions to β

Electroabsorption or Stark effect spectroscopy has been applied to a pair of porphyrin-based chromophores with the aim of deriving a detailed understanding of the origin of the remarkable first hyperpolarizability, β, of one of the chromophores: [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4- nitrophenyl)-ethynyl]-10,20-diphenylporphinato]zinc(II). The measurements show that significant changes in molecular dipole moment, Δμ, accompany excitations of x-polarized transitions of the aminophenyl (donor)/nitrophenyl (acceptor) functionalized chromophore, but are absent for a related chromophore lacking the donor and acceptor groups. For linear chromophores, changes in dipole moment are a prerequisite to effective molecular first hyperpolarization and incident light frequency doubling behavior. A more detailed consideration of the available |Δμ| data, within the context of a conventional two-level model, has yielded the following: (a) specific information about the roles of each of seven electronic and vibronic excited states in defining β, (b) a semiquantitative explanation for the apparent frequency independence of β found in previous hyper-Rayleigh scattering experiments performed at 830 and 1064 nm, and (c) an explanation for the contrasting frequency dependence of the nonlinear optical response for the analogous Cu(II)-containing chromophore. Finally, the experimental findings are in generally good agreement with published ZINDO calculations which had pointed toward the exceptional effectiveness of yne linkages in coupling donor and acceptor moieties to the highly polarizable porphyrin core assembly.

Authors
Karki, L; Vance, FW; Hupp, JT; LeCours, SM; Therien, MJ
MLA Citation
Karki, L, Vance, FW, Hupp, JT, LeCours, SM, and Therien, MJ. "Electronic stark effect studies of a porphyrin-based push-pull chromophore displaying a large first hyperpolarizability: State-specific contributions to β." Journal of the American Chemical Society 120.11 (1998): 2606-2611.
Source
scival
Published In
Journal of the American Chemical Society
Volume
120
Issue
11
Publish Date
1998
Start Page
2606
End Page
2611
DOI
10.1021/ja973593v

High-pressure NMR studies of (porphinato)iron-catalyzed isobutane oxidation utilizing dioxygen as the stoichiometric oxidant

Authors
Moore, KT; Horvath, IT; Therien, MJ
MLA Citation
Moore, KT, Horvath, IT, and Therien, MJ. "High-pressure NMR studies of (porphinato)iron-catalyzed isobutane oxidation utilizing dioxygen as the stoichiometric oxidant." Journal of the American Chemical Society 119.7 (1997): 1791-1792.
Source
scival
Published In
Journal of the American Chemical Society
Volume
119
Issue
7
Publish Date
1997
Start Page
1791
End Page
1792
DOI
10.1021/ja961531j

Synthesis, transient absorption, and transient resonance Raman spectroscopy of novel electron donor-acceptor complexes: [5,15-bis[(4'- nitrophenyl)ethynyl]-10,20-diphenylporphinato]copper(II) and [5-[[4'- (dimethylamino)phenyl]ethynyl]-15-[(4-nitrophenyl)ethynyl]-10,20-diphenyl- porphinato]copper(II)

We report the synthesis, transient absorption, FT Raman, resonance Raman, time-resolved resonance Raman, and transient resonance Raman spectra of pseudo-D(2h) symmetric [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20- diphenylporphinato]copper(II) (I) and electronically asymmetric [5-[4'- (dimethylamino)phenyl]ethynyl]-15-[(4-nitrophenyl)-ethynyl]-10,20- diphenylporphinato]copper(II) (II), which bears both electron-releasing and electron-withdrawing groups conjugated directly to the porphyrin periphery. The spectroscopic results suggest extensive electronic communication between the 5- and 15-arylethynyl groups and the porphyrin core. Relative to the parent compound, (tetraphenylporphinato)copper(II) (CuTPP), the arylethynyl substituents increase the lifetime of the excited trip-multiplet states. CuTPP, as well as compounds I and II, however, shows similar solvent- dependent dynamics: the trip-multiplet lifetimes are longer in a noncoordinating solvent such as benzene than in a coordinating solvent such as THF. This behavior is consistent with the existence of a quenching state whose effect is more pronounced upon coordination of solvent. The time- resolved resonance Raman spectrum of compound II shows features commonly associated with the relatively long-lived triplet excited states of copper(II) porphyrins. The transient resonance Raman spectrum of a short- lived excited state present in both compounds I and H is characterized by marked shifts in the nitro and porphyrin stretching frequencies relative to that observed for the ground states of both (4-nitrophenyl)-ethyne and (tetraphenylporphinato)copper(II). We interpret these results for the compounds I and II as arising from (i) a short-lived excited state present at early time that possesses enhanced porphyrin-to-nitro charge-transfer character with respect to the ground state and (ii) a longer-lived excited state deriving from this initially probed charge-transfer state that is largely porphyrin localized.

Authors
LeCours, SM; Philips, CM; Paula, JCD; Therien, MJ
MLA Citation
LeCours, SM, Philips, CM, Paula, JCD, and Therien, MJ. "Synthesis, transient absorption, and transient resonance Raman spectroscopy of novel electron donor-acceptor complexes: [5,15-bis[(4'- nitrophenyl)ethynyl]-10,20-diphenylporphinato]copper(II) and [5-[[4'- (dimethylamino)phenyl]ethynyl]-15-[(4-nitrophenyl)ethynyl]-10,20-diphenyl- porphinato]copper(II)." Journal of the American Chemical Society 119.51 (1997): 12578-12589.
Source
scival
Published In
Journal of the American Chemical Society
Volume
119
Issue
51
Publish Date
1997
Start Page
12578
End Page
12589
DOI
10.1021/ja964436j

Acetylenyl-linked, porphyrin-bridged, donor-acceptor molecules: A theoretical analysis of the molecular first hyperpolarizability in highly conjugated push-pull chromophore structures

We described the theoretical basis for the exceptionally large molecular first hyperpolarizabilities inherent to (5,15-diethynyl)porphinato)metal-bridged donor-acceptor (D-A) molecules. β values relevant for hyper-Rayleigh experiments are calculated at 1.064 and 0.830 μm for a complex with such a structure, [5-((4'-dimethylamino)phenyl)ethynyl)-15-((4''-nitrophenyl)ethynyl)-10 ,20-diphenylporphinato]zinc(II), and are 472 x 10-30 and 8152 x 10-30 cm5/esu, respectively. The values are 1 order of magnitude larger than that calculated for any other porphyrin bridged donor-acceptor chromophore studied to date. The considerably enhanced hyperpolarizability arises from the significant excited-state electronic asymmetry manifest in such structures (derived from the strong bridge-mediated D-A coupling enabled by the largely porphyrin-based excited state) and the large bridge-centered oscillator strength in this new class of D-bridge-A molecules. Our analysis of NLO properties (based upon INDO/SCI calculations within the sum over states formalism) shows a sensitivity to the degree of cumulenic character in the ground state. Calculations on structurally related multiporphyrin systems suggest candidate chromophores with further enhanced optical nonlinearities.

Authors
Priyadarshy, S; Therien, MJ; Beratan, DN
MLA Citation
Priyadarshy, S, Therien, MJ, and Beratan, DN. "Acetylenyl-linked, porphyrin-bridged, donor-acceptor molecules: A theoretical analysis of the molecular first hyperpolarizability in highly conjugated push-pull chromophore structures." Journal of the American Chemical Society 118.6 (1996): 1504-1510.
Source
scival
Published In
Journal of the American Chemical Society
Volume
118
Issue
6
Publish Date
1996
Start Page
1504
End Page
1510
DOI
10.1021/ja952690q

Exceptional electronic modulation of porphyrins through meso-arylethynyl groups. Electronic spectroscopy, electronic structure, and electrochemistry of [5,15-bis](aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes

A new class of porphyrins in which intervening ethynyl moieties connect aryl groups to the porphyrin 5 and 15-positions is described. The synthesis and optical spectroscopy of five new compounds are reported: [5,15-bis[(4'-dimethylaminophenyl)ethynyl]-10,20-diphenylporphinato]zi nc(II), [5,15-bis[(4'-methoxyphenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) , [5,15-bis[(phenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), [5, 15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), and [5,15-bis[(4'-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II). The X-ray structure of one of these complexes, [5,15-bis[(4'-fluorophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II), is unusual in that it shows the arylethynyl-phenyl rings to be coplanar with the porphyrin macrocycle. This arrangement of aryl rings with respect to the porphyrin macrocycle underscores the fact that the steric barrier to rotation between the porphyrin and arylethynyl-phenyl aromatic systems has been removed and highlights the enhanced π-conjugative interactions responsible for the unusual electronic characteristics of these molecules. Electronic spectroscopy and electrochemistry of these systems evince the ability of this new porphyrin structural motif to modulate extensively chromophore electronic structure. ZINDO-determined (INDO-1 semiempirical parameters; CI level = 20) frontier orbital energies for the [5,15-bis[(aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes demonstrate that these properties derive from energetic differences between the porphyrin HOMO and HOMO-1 and a substantial splitting of the formerly degenerate porphyrin LUMO; these significant electronic perturbations (relative to simple (porphinato)zinc(II) complexes) are manifest in the fact that the low lying singlet excited states of these compounds are highly polarized.

Authors
LeCours, SM; DiMagno, SG; Therien, MJ
MLA Citation
LeCours, SM, DiMagno, SG, and Therien, MJ. "Exceptional electronic modulation of porphyrins through meso-arylethynyl groups. Electronic spectroscopy, electronic structure, and electrochemistry of [5,15-bis](aryl)ethynyl]-10,20-diphenylporphinato]zinc(II) complexes." Journal of the American Chemical Society 118.47 (1996): 11854-11864.
Source
scival
Published In
Journal of the American Chemical Society
Volume
118
Issue
47
Publish Date
1996
Start Page
11854
End Page
11864
DOI
10.1021/ja962403y

Synthesis, structure, electronic spectroscopy, photophysics, electrochemistry, and X-ray photoelectron spectroscopy of highly-electron-deficient [5,10,15,20-tetrakis(perfluoroalkyl)porphinato]zinc(II) complexes and their free base derivatives

The synthesis, optical spectroscopy, photophysical properties, electrochemistry, and X-ray photoelectron spectroscopy of a series of [5,10,15,20-tetrakis(perfluoroalkyl)porphinato]zinc(II) complexes and their free base analogs are reported. The title compounds were prepared by a condensation methodology that utilizes perfluoro-1-(2'-pyrrolyl)-1-alkanol precursors and employs continuous water removal throughout the course of the reaction to yield the meso perfluorocarbon-substituted porphyrins. The nature of the porphyrin-pendant meso-perfluoroalkyl group exerts considerable influence over the macrocycle's solubility properties. The structure of the monopyridyl adduct of [5,10,15,20-tetrakis(heptafluoropropyl)porphinato]zinc(II) features an S4-distorted porphyrin core; X-ray data are as follows: P1̄ with a = 15.1330(5) Å, b = 19.2780(6) Å, c = 14.6030(4) Å, α = 110.220(2)°, β = 103.920(2)°, γ = 85.666(2)°, V= 3880.1(2) Å3, d(calc) = 1.887 g cm-3, and Z = 4. Electrochemical studies carried out on these porphyrin and (porphinato)zinc(II) complexes indicate that meso-perfluoroalkylporphyrins are among the most electron-deficient porphyrinic species known. X-ray photoelectron spectroscopy experiments corroborate the electron poor nature of these systems and evince extreme stabilization of the nitrogen 1 s orbitals, consonant with particularly effective removal of electron density from the macrocycle by the meso-perfluoroalkyl moieties that is modulated by σ-symmetry orbitals. The photophysical properties of these compounds differ from all other previously reported highly electron deficient porphyrin macrocycles in that they possess long-lived, fluorescent excited states; hence their optoelectronic features are consistent with a variety of excited-state electron-transfer quenching schemes in which both 1ZnP* and 1H2P* can be utilized as potent photooxidants.

Authors
Goll, JG; Moore, KT; Ghosh, A; Therien, MJ
MLA Citation
Goll, JG, Moore, KT, Ghosh, A, and Therien, MJ. "Synthesis, structure, electronic spectroscopy, photophysics, electrochemistry, and X-ray photoelectron spectroscopy of highly-electron-deficient [5,10,15,20-tetrakis(perfluoroalkyl)porphinato]zinc(II) complexes and their free base derivatives." Journal of the American Chemical Society 118.35 (1996): 8344-8354.
Source
scival
Published In
Journal of the American Chemical Society
Volume
118
Issue
35
Publish Date
1996
Start Page
8344
End Page
8354
DOI
10.1021/ja9610904

Synthesis of (porphinato)zinc(II)-spacer-(porphinato)iron(III) chloride complexes: A modular approach to fixed-distance electron-transfer model compounds through the efficacy of metal-mediated cross-coupling

The syntheses of (porphinato)zinc(II)-spacer-(porphinato)iron(III) chloride complexes were effected by the agency of Pd-catalyzed cross-coupling of two equivalents of [5-bromo-10,20-diphenyl-15-(4′-methoxyphenyl)porphinato]zinc with a symmetric bis(trimethyltin) derivative of a rigid organic spacer molecule, followed by a demetalation-remetalation reaction sequence. The approach described herein represents a new strategy for assembling porphyrin-based donor-spacer-acceptor compounds that is predicated on the modular syntheses of rigid donor, acceptor, and spacer molecules.

Authors
Rege, PJFD; Therien, MJ
MLA Citation
Rege, PJFD, and Therien, MJ. "Synthesis of (porphinato)zinc(II)-spacer-(porphinato)iron(III) chloride complexes: A modular approach to fixed-distance electron-transfer model compounds through the efficacy of metal-mediated cross-coupling." Inorganica Chimica Acta 242.1-2 (1996): 211-218.
Source
scival
Published In
Inorganica Chimica Acta
Volume
242
Issue
1-2
Publish Date
1996
Start Page
211
End Page
218

Thermally stable, highly nonlinear porphyrin-based chromophores in poled host-guest thin films

A new class of chromophores has been fabricated that features both electron-releasing and electron-withdrawing groups fused via an intervening ethynyl moiety to the carbon framework of a (porphinato)metal complex. These species possess a number of unusual optical properties that include molecular first-order hyperpolarizabilities (β) of exceptional magnitude. [5-(4′-dimethylaminophenylethynyl)- 15-(4″-nitrophenylethynyl)-10,20-diphenylporphinato]copper(II) and [5-(4′-dimethylaminophenylethynyl)-15-(4″-nitrophenylethynyl )-10,20-diphenylporphinato]zinc(II) represent two archetypal members of this new class of exceptional nonlinear chromophores. One of these compounds, [5-(4′-dimethylaminophenylethynyl)- 15-(4″-nitrophenylethynyl)-10,20-diphenylporphinato]zinc(II), possesses β values near 5000×10-30 esu at incident irradiation wavelengths of both 830 and 1064 nm and an off resonant β(0) value of approximately 800×10-30 esu. A β(0) value of this magnitude indicates that these prototype chromophores based on our new design criteria rank with the very best organic chromophores for second harmonic generation that have been fabricated to date. This fact coupled with the observation that these chromophores are stable to heating at 250 °C in thin polyimide films, suggests that modification and elaboration of these structural motifs will dramatically impact the development of electrooptic devices as well as materials for efficient frequency doubling of incident irradiation (second harmonic generation).

Authors
Therien, MJ; LeCours, SM; Wang, C-H; Guan, H-W; Jen, AK-Y; Cai, Y-M
MLA Citation
Therien, MJ, LeCours, SM, Wang, C-H, Guan, H-W, Jen, AK-Y, and Cai, Y-M. "Thermally stable, highly nonlinear porphyrin-based chromophores in poled host-guest thin films." Journal of Engineering and Applied Science 2 (1996): 1482-1483.
Source
scival
Published In
Journal of Engineering and Applied Science
Volume
2
Publish Date
1996
Start Page
1482
End Page
1483

Push-pull arylethynyl porphyrins: New chromophores that exhibited large molecular first-order hyperpolarizabilities

A new class of chromophores has been fabricated that features both electron-releasing and electron-withdrawing groups fused via an intervening ethynyl moiety to the carbon framework of a (porphinato)metal complex. These species possess large molecular first-order hyperpolarizabilities (β). We report herein the synthesis, optical spectroscopy, and the hyper-Rayleigh scattering data used to determine the β values of two archetypal members of this new class of exceptional nonlinear chromophores: [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-1 0,20-diphenylporphinato]copper(II) and [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-1 0,20-diphenyl]porphinato]zinc(II). One of these compounds, [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4''-nitrophenyl)ethynyl]-1 0,20-diphenylporphinato]zinc(II), possesses β values near 5000 x 10-30 esu at incident irradiation wavelengths of both 830 and 1064 nm. These studies suggest that this chromophoric structural motif may find utility in the development of electrooptic devices as well as materials for efficient frequency doubling of incident irradiation (second harmonic generation).

Authors
LeCours, SM; Guan, H-W; DiMagno, SG; Wang, CH; Therien, MJ
MLA Citation
LeCours, SM, Guan, H-W, DiMagno, SG, Wang, CH, and Therien, MJ. "Push-pull arylethynyl porphyrins: New chromophores that exhibited large molecular first-order hyperpolarizabilities." Journal of the American Chemical Society 118.6 (1996): 1497-1503.
Source
scival
Published In
Journal of the American Chemical Society
Volume
118
Issue
6
Publish Date
1996
Start Page
1497
End Page
1503
DOI
10.1021/ja953610l

The Role of Porphyrin-to-Porphyrin Linkage Topology in the Extensive Modulation of the Absorptive and Emissive Properties of a Series of Ethynyl- and Butadiynyl-Bridged Bis- and Tris(porphinato)zinc Chromophores

Authors
Lin, VS-Y; Therien, MJ
MLA Citation
Lin, VS-Y, and Therien, MJ. "The Role of Porphyrin-to-Porphyrin Linkage Topology in the Extensive Modulation of the Absorptive and Emissive Properties of a Series of Ethynyl- and Butadiynyl-Bridged Bis- and Tris(porphinato)zinc Chromophores." Chemistry - A European Journal 1.9 (December 1995): 645-651.
Source
crossref
Published In
Chemistry - A European Journal
Volume
1
Issue
9
Publish Date
1995
Start Page
645
End Page
651
DOI
10.1002/chem.19950010913

Direct evaluation of electronic coupling mediated by hydrogen bonds: implications for biological electron transfer.

Three supramolecular bischromophoric systems featuring zinc(II) and iron(III) porphyrins have been synthesized to evaluate the relative magnitudes of electronic coupling provided by hydrogen, sigma, and pi bonds. Laser flash excitation generates the highly reducing singlet excited state of the (porphinato)zinc chromophore that can subsequently be electron transfer quenched by the (porphinato)iron(III) chloride moiety. Measurement of the photoinduced electron transfer rate constants enables a direct comparison of how well these three types of chemical interactions facilitate electron tunneling. In contrast to generally accepted theory, electronic coupling modulated by a hydrogen-bond interface is greater than that provided by an analogous interface composed entirely of carbon-carbon sigma bonds. These results bear considerably on the analysis of through-protein electron transfer rate data as well as on the power of theory to predict the path traversed by the tunneling electron in a biological matrix; moreover, they underscore the cardinal role played by hydrogen bonds in biological electron transfer processes.

Authors
de Rege, PJ; Williams, SA; Therien, MJ
MLA Citation
de Rege, PJ, Williams, SA, and Therien, MJ. "Direct evaluation of electronic coupling mediated by hydrogen bonds: implications for biological electron transfer." Science 269.5229 (September 8, 1995): 1409-1413.
PMID
7660123
Source
pubmed
Published In
Science
Volume
269
Issue
5229
Publish Date
1995
Start Page
1409
End Page
1413

Porphyrin-quinone electron transfer revisited. The role of excited-state degeneracy in ultrafast charge transfer reactions

Ultrafast time-resolved anisotropy experiments in which electronically excited [5-(1′,4′-benzoquinonyl)-10,15,20-triphenylporphinato]magnesium (MgPQ) was probed with polarization both parallel and perpendicular to the pump pulse have been carried out in a variety of solvents. These results show that the photoinduced electron transfer process involving the locally-excited MgP*Q state is solvent independent, while the thermal charge recombination reaction is solvent dependent. Moreover, these studies indicate that the photoinduced charge separation reaction may be rate-limited by electronic population equilibration between near degenerate porphyrin Qx and Qy levels.

Authors
Wynne, K; LeCours, SM; Galli, C; Therien, MJ; Hochstrasser, RM
MLA Citation
Wynne, K, LeCours, SM, Galli, C, Therien, MJ, and Hochstrasser, RM. "Porphyrin-quinone electron transfer revisited. The role of excited-state degeneracy in ultrafast charge transfer reactions." Journal of the American Chemical Society 117.13 (1995): 3749-3753.
Source
scival
Published In
Journal of the American Chemical Society
Volume
117
Issue
13
Publish Date
1995
Start Page
3749
End Page
3753

EPR spectroscopy and photophysics of the lowest photoactivated triplet state of a series of highly conjugated (porphinato)Zn arrays

The lowest photoexcited metastable triplet state of a family of highly conjugated (porphinato)zinc(II) arrays in which ethyne or butadiyne units bridge the macrocycle carbon frameworks, along with their ethyne- and butadiyne-elaborated monomeric porphyrinic building blocks, and parent (porphinato)zinc(II) precursor molecules were studied by electron paramagnetic resonance (EPR), transient triplet-triplet absorption, and phosphorescence emission. All EPR spectra of the excited monomeric precursors and dimeric and trimeric porphyrin arrays reflect symmetries of rhombic distortion |D| ≥ 3 |E|) at 4 K and exhibit electron spin polarization patterns verifying that intersystem crossing from the first excited singlet state occurs predominantly through the |T(z)> spin state sublevel. The zero field splitting (ZFS) parameters of the (porphinato)zinc monomers that bear ethynyl and butadiynyl groups as well as the conjugated porphyrin arrays are essentially temperature independent over a 4-100 K temperature range. This behavior is in contrast to the line shape changes typically seen in most monomeric closed-shell metalloporphyrin triplet states, signifying that the lowest excited triplet state possesses a symmetry lower than D(4h) and hence not susceptible to Jahn-Teller instabilities. The magnitudes of the D values for all compounds except the meso-to-meso butadiyne-linked dimer lie in the range expected for monomeric (porphinato)zinc complexes, indicating that (1) there is no global delocalization of the triplet excitation and (2) the excitation can be considered to be localized on one of the monomeric subunits in the conjugated supramolecular chromophoric systems on the time scale probed by EPR. The type and mode of chromophore-to-chromophore connectivity does effect both spin distribution and spin alignment in the low temperature photoactivated triplet states of conjugated (porphinato)zinc arrays. For example, in the meso-to-meso butadiyne linked dimer, the |D| value actually increases approximately 30% with respect to its monomeric precursor; this anomaly is interpreted as resulting from spin alignment in the molecular plane. A most striking feature is the persistence of electron spin polarization in most of the dimeric and trimeric porphyrin arrays under conditions of steady state illumination up to temperatures approaching the glass transition temperature (T ~ 120 K). Progressive power saturation experiments carried out on one of the dimeric porphyrin systems, in which an ethyne moiety bridges two (porphinato)zinc chromophores at their respective meso-carbon positions, reveals an exceptionally weak temperature dependence on the saturation parameter, P( 1/2 ), along with no significant changes in either the ZFS parameters or line widths with increasing microwave power or temperature, indicating that spin lattice relaxation is long relative to de-excitation to the ground state over a broad temperature range. This anomalous effect is discussed from the standpoint of relaxation occurring primarily through matrix disorder modes.

Authors
Angiolillo, PJ; Lin, VS-Y; Vanderkooi, JM; Therien, MJ
MLA Citation
Angiolillo, PJ, Lin, VS-Y, Vanderkooi, JM, and Therien, MJ. "EPR spectroscopy and photophysics of the lowest photoactivated triplet state of a series of highly conjugated (porphinato)Zn arrays." Journal of the American Chemical Society 117.50 (1995): 12514-12527.
Source
scival
Published In
Journal of the American Chemical Society
Volume
117
Issue
50
Publish Date
1995
Start Page
12514
End Page
12527
DOI
10.1021/ja00155a015

Highly conjugated, acetylenyl bridged porphyrins: new models for light-harvesting antenna systems.

A new class of porphyrin-based chromophore systems has been prepared from ethyne-elaborated porphyrin synthons through the use of metal-mediated cross-coupling methodologies. These systems feature porphyrin chromophores wired together through single ethynyl linkages. This type of topological connectivity affords exceptional electronic interactions between the chromophores which are manifest in their room temperature photophysics, optical spectroscopy, and electrochemistry; these spectroscopic signatures indicate that these species model many of the essential characteristics of biological light-harvesting antenna systems.

Authors
Lin, VS; DiMagno, SG; Therien, MJ
MLA Citation
Lin, VS, DiMagno, SG, and Therien, MJ. "Highly conjugated, acetylenyl bridged porphyrins: new models for light-harvesting antenna systems." Science 264.5162 (May 20, 1994): 1105-1111.
PMID
8178169
Source
pubmed
Published In
Science
Volume
264
Issue
5162
Publish Date
1994
Start Page
1105
End Page
1111

Facile synthesis of meso-tetrakis(perfluoroalkyl)porphyrins: Spectroscopic properties and X-ray crystal structure of highly electron-deficient 5,10,15,20-tetrakis(heptafluoropropyl)porphyrin

The synthesis, structure, optical spectrum, and electrochemistry of 5,10,15,20-tetrakis(perfluoropropyl)porphyrin, 1, are reported. The high yield preparative method, starting from (hydroxymethyl)pyrrole precursors such as 2,2,3,3,4,4,4-heptafluoro-1-(2-pyrrolyl)-1-butanol, 2, is general for a wide variety of meso-perfluoroalkyl-substituted porphyrins. The X-ray crystal structure of 1 is noteworthy in that it shows a S4-distorted porphyrin core that appears to derive from an unusual hydrogen bonding interaction between a fluorocarbon fluorine atom and a porphyrin NH proton. A comparison of the electrochemical properties of the zinc derivative of 1 with those of [5,10,15,-20-tetrakis(pentafluorophenyl)-2,3,7,8,12,13,17,18- octabromoporphinato]zinc(II) indicates that meso-perfluoroalkylated porphyrins are among the most electron-deficient porphyrin ligands known. meso-Tetrakis(perfluoroalkyl)porphyrins and their elaborated derivatives, with their unusual electronic properties, should thus serve as useful ligands for a variety of catalytic and stoichiometric transition metal-mediated redox reactions. © 1994 American Chemical Society.

Authors
DiMagno, SG; Williams, RA; Therien, MJ
MLA Citation
DiMagno, SG, Williams, RA, and Therien, MJ. "Facile synthesis of meso-tetrakis(perfluoroalkyl)porphyrins: Spectroscopic properties and X-ray crystal structure of highly electron-deficient 5,10,15,20-tetrakis(heptafluoropropyl)porphyrin." Journal of Organic Chemistry 59.23 (1994): 6943-6948.
Source
scival
Published In
The Journal of Organic Chemistry
Volume
59
Issue
23
Publish Date
1994
Start Page
6943
End Page
6948

Direct measurement of electronic dephasing using anisotropy

In a recent theoretical treatment of coherence effects in the anisotropy of optical experiments, it was predicted that the decay of the anisotropy that exists for molecules with degenerate states prior to the onset of electronic dephasing could be utilized to measure electronic dephasing directly. The first experimental observation of this coherent anisotropy and its ultrafast decay are presented. The data were obtained by means of femtosecond pump-probe experiments on room temperature solutions of magnesium tetraphenylporphyrin in tetrahydrofuran. In this system, which has a doubly degenerate excited state due to the fourfold molecular symmetry, the anisotropy decays with time constants 210 fs and 1.6 ps. © 1993.

Authors
Galli, C; Wynne, K; LeCours, SM; Therien, MJ; Hochstrasser, RM
MLA Citation
Galli, C, Wynne, K, LeCours, SM, Therien, MJ, and Hochstrasser, RM. "Direct measurement of electronic dephasing using anisotropy." Chemical Physics Letters 206.5-6 (1993): 493-499.
Source
scival
Published In
Chemical Physics Letters
Volume
206
Issue
5-6
Publish Date
1993
Start Page
493
End Page
499
DOI
10.1016/0009-2614(93)80174-N

Vibrational coherence in charge transfer

We present the first ultrafast studies on free-base triphenyl-porphyrin-quinone(5-(1',-4'-benzoquinonyl)-10,15, 20-triphenylporphyrin or PQ).There are strong indications that coherence of nuclear or electronic origin plays a role in the ET transfer reaction in PQ complexes.

Authors
Wynne, K; Galli, C; Rege, PJFD; Therien, MJ; Hochstrasser, RM
MLA Citation
Wynne, K, Galli, C, Rege, PJFD, Therien, MJ, and Hochstrasser, RM. "Vibrational coherence in charge transfer." Springer Series in Chemical Physics 55 (1993): 71-73.
Source
scival
Published In
Springer Series in Chemical Physics
Issue
55
Publish Date
1993
Start Page
71
End Page
73

Facile elaboration of porphyrins via metal-mediated cross-coupling

Metal-mediated cross-coupling methodologies have been successfully employed to porphyrinic systems, providing a powerful, versatile, and general synthetic approach for the fabrication of elaborated porphyrin structures. A large number of coupling reactions have been carried out at two halogenated porphyrin templates, [2-bromo-5,10,15,20-tetraphenylporphinato]zinc and [5,15-dibromo-10,20-diphenylporphinato]zinc, generating a variety of porphyrins, 10 of which are novel: [2-n-butyl-5,-10,15,20-tetraphenylporphinato]zinc(II), [2-(2,5-dimethoxyphenyl)-5,10,15,20-tetraphenylporphinato]-zinc(II), [2-(9-anthracenyl)-5,10,15,20-tetraphenylporphinato]zinc(II), [2-vinyl-5,10,15,20-tetraphenylporphinato]zinc(II), [2,5,10,15,20-pentaphenylporphinato]zinc(II), [2-isobutyl-5,10,15,20-tetraphenylporphinato]zinc(II), [2-(pentafluorophenyl)-5,10,15,20-tetraphenylporphinato]zinc(II), [5,15-bis-[[2-(4′-methyl-2′-pyridyl)-4-pyridyl]methyl]-10,20- diphenylporphinato]zinc(II), [5,15-dimethyl-10,20-diphenylporphinato]zinc(II), [5,15-divinyl-10,20-diphenylporphinato]zinc(II), [5,15-bis(2,5-dimethoxyphenyl)-10-diphenylporphinato]zinc(II), and [5,15-bis(pentafluorophenyl)-10,20-diphenylporphinato]zinc(II). The structures of [2,5,10,15,20-pentaphenylporphinato]zinc(II) and 5,15-bis-(pentafluorophenyl)-10,20-diphenylporphyrin have been determined; X-ray data are as follows: P21/n with a = 21.425(4) Å, b = 9.718(1) Å, c = 24.905(2) Å, β = 110.83(1)°, V = 4846(3) Å3, dcalc = 1.260 g cm-3, and Z = 4 for the former; and P21/c with a = 15.223(2) Å, b = 10.162(1) Å, c = 12.375(2) Å, β = 112.75(2)°, V = 1765.6(9) Å3, dcalc = 1.495 g cm-3, and Z = 2 for the latter. This study demonstrates that cross-coupling reactions at the porphyrin periphery are seemingly not subject to the steric or electronic constraints that often limit the scope of these reactions in simple aryl and vinyl systems. © 1993 American Chemical Society.

Authors
DiMagno, SG; Lin, VS-Y; Therien, MJ
MLA Citation
DiMagno, SG, Lin, VS-Y, and Therien, MJ. "Facile elaboration of porphyrins via metal-mediated cross-coupling." Journal of Organic Chemistry 58.22 (1993): 5983-5993.
Source
scival
Published In
The Journal of Organic Chemistry
Volume
58
Issue
22
Publish Date
1993
Start Page
5983
End Page
5993

Electrochemical studies of an oxidatively induced ring slippage in 17-electron (η3-indenyl)(η5-indenyl)V(CO)2

Oxidation of (η5-arene)2V (arene = indenyl, C5H5, C5Me5) with [(C5H5)2Fe][PF6] under a carbon monoxide atmosphere provides a convenient route to [(η5-arene)2V(CO)2]+ complexes. The cyclic voltammogram of the indenyl compound shows two reversible one-electron reduction waves. Reduction of 18-electron [(η5-indenyl)2V(CO)2][PF6 ] leads directly to the 17-electron (η3-indenyl)(η5-indenyl)V-(CO)2 . A lower limit for the η3-to-η5 ring slip rate constant is estimated to be 10/sec at -32°C. Reductions of the cationic C5H5 and C5Me5 analogues were irreversible and showed no evidence for ring slipped intermediates. © 1990.

Authors
Miller, GA; Therien, MJ; Trogler, WC
MLA Citation
Miller, GA, Therien, MJ, and Trogler, WC. "Electrochemical studies of an oxidatively induced ring slippage in 17-electron (η3-indenyl)(η5-indenyl)V(CO)2." Journal of Organometallic Chemistry 383.1-3 (1990): 271-278.
Source
scival
Published In
Journal of Organometallic Chemistry
Volume
383
Issue
1-3
Publish Date
1990
Start Page
271
End Page
278
DOI
10.1016/0022-328X(90)85136-M

Long-range electron transfer in ruthenium-modified cytochrome c: Evaluation of porphyrin-ruthenium electronic couplings in the Candida krusei and horse heart proteins

Authors
Therien, MJ; Selman, M; Gray, HB; Chang, I-J; Winkler, JR
MLA Citation
Therien, MJ, Selman, M, Gray, HB, Chang, I-J, and Winkler, JR. "Long-range electron transfer in ruthenium-modified cytochrome c: Evaluation of porphyrin-ruthenium electronic couplings in the Candida krusei and horse heart proteins." Journal of the American Chemical Society 112.6 (1990): 2420-2422.
Source
scival
Published In
Journal of the American Chemical Society
Volume
112
Issue
6
Publish Date
1990
Start Page
2420
End Page
2422

Spectroscopic, structural, electrochemical, and kinetic studies of ligand substitution in the 33e dinuclear radical Fe2(CO)7(.mu.-PPh2) and the 34e analogs [Fe2(CO)7(.mu.-PPh2)]- and FeCo(CO)7(.mu.-PPh2)

Authors
Baker, RT; Calabrese, JC; Krusic, PJ; Therien, MJ; Trogler, WC
MLA Citation
Baker, RT, Calabrese, JC, Krusic, PJ, Therien, MJ, and Trogler, WC. "Spectroscopic, structural, electrochemical, and kinetic studies of ligand substitution in the 33e dinuclear radical Fe2(CO)7(.mu.-PPh2) and the 34e analogs [Fe2(CO)7(.mu.-PPh2)]- and FeCo(CO)7(.mu.-PPh2)." Journal of the American Chemical Society 110.25 (December 1988): 8392-8412.
Source
crossref
Published In
Journal of the American Chemical Society
Volume
110
Issue
25
Publish Date
1988
Start Page
8392
End Page
8412
DOI
10.1021/ja00233a017

Spectroscopic, structural, electrochemical, and kinetic studies of ligand substitution in the 33e dinuclear radical Fe2(CO)7(μ-PPh2) and the 34e analogues [Fe2(CO)7(μ-PPh2)]- and FeCo(CO)7(μ-PPh2)

The 33e dinuclear radical Fe2(CO)7(μ-PPh2) undergoes rapid CO ligand substitution with a variety of tertiary phosphorus ligands, L, to give mono- and disubstituted 33e products, which were characterized by elemental analysis and by IR and ESR spectroscopy. While the first substitution gives a single product, with L on the six-coordinate Fe center trans to the PPh2 bridge (confirmed by X-ray diffraction for L = P(OMe)3), further substitution (observed for L = PMe3, PEt3, P(OMe)3) is complex, giving two isomeric 33e disubstituted radicals, minor amounts of 35e addition products Fe2(CO)6L2(μ-PPh2), and diamagnetic disproportionation products [Fe2(CO)5L3(μ-PPh2)] +[Fe2(CO)8-nLn(μ-PPh 2)]- (L = PMe3, n = 0; L = P(OMe)3, n = 2), as confirmed by an X-ray diffraction study of the PMe3 derivative. The 34e anion [Fe2(CO)6(μ-CO)(μ-PPh2)]-, as the (Et4N)+ salt, adds two ligands in THF to give the 36e anions [Fe2(CO)6L2(μ-PPh2)]- (L = PMe3, PPh3, P(OMe)3), which have one L on each Fe, both trans to the PPh2 bridge (confirmed by X-ray diffraction for L = PPh3). The intermediacy of the monosubstituted 34e anion was ruled out. The 34e heterobimetallic complex FeCo(CO)7(μ-PPh2) reacts with PPh3 to give a 34e kinetic product with L on Co trans to the PPh2 bridge; this product rearranges at 25°C to the thermodynamic product with L on Fe. With P(OMe)3, monosubstitution occurs as above and disubstitution gives both 34e and 36e products, both with one L on each metal (confirmed for the 34e product by X-ray diffraction). With PMe3, ligand addition gives 36e FeCo(CO)7L(μ-PPh2), with L on Co. Electrochemical studies show that the 33e unsubstituted and monosubstituted diiron radicals exhibit chemically reversible 1e reductions to give the 34e CO-bridged anions. A 1e oxidation of the disubstituted 36e anion [Fe2(CO)6(PPh3)2(μ-PPh 2)]- leads to the monosubstituted 33e radical, via loss of PPh3. While oxidation of 34e FeCo(CO)7(μ-PPh2) is chemically irreversible, 1e reduction leads to CO loss to give the 33e radical anion [FeCo(CO)6(μ-PPh2)]-, which undergoes a further chemically reversible reduction to the 34e dianion. Similarly, 1e reduction of monosubstituted FeCo(CO)6(PPh3)(μ-PPh2) gives the 33e monosubstituted radical anion via CO loss, while a chemically reversible 1e oxidation gives the 33e radical cation [FeCo(CO)6(PPh3)(μ-PPh2)]+. Kinetic studies of ligand monosubstitution in the 33e diiron radical Fe2(CO)7(μ-PPh2) using transient electrochemical techniques are consistent with an associative mechanism involving a 35e radical intermediate. Activation parameters obtained support the proposed associative pathway. Comparison of the reactivities of 33e Fe2(CO)7(μ-PPh2) and its 34e analogues [Fe2(CO)6(μ-CO)(μ-PPh2)]- and FeCo(CO)7(μ-PPh2) show that the radical complex is about 105-106 times more reactive toward PPh3 than the diamagnetic 34e compounds. The mono- and disubstituted 35e radicals have been observed by ESR spectroscopy for various L's and are proposed to have a (CO)2-bridged structure, with two six-coordinate metal centers. Analogous 36e intermediates in the [Fe2]- and FeCo systems have the all-terminal-CO structure, with two five-coordinate metal centers. © 1988 American Chemical Society.

Authors
Baker, RT; Calabrese, JC; Krusic, PJ; Therien, MJ; Trogler, WC
MLA Citation
Baker, RT, Calabrese, JC, Krusic, PJ, Therien, MJ, and Trogler, WC. "Spectroscopic, structural, electrochemical, and kinetic studies of ligand substitution in the 33e dinuclear radical Fe2(CO)7(μ-PPh2) and the 34e analogues [Fe2(CO)7(μ-PPh2)]- and FeCo(CO)7(μ-PPh2)." Journal of the American Chemical Society 110.25 (1988): 8392-8412.
Source
scival
Published In
Journal of the American Chemical Society
Volume
110
Issue
25
Publish Date
1988
Start Page
8392
End Page
8412

Theoretical study of bimolecular nucleophilic substitution at four-, five-, and six-coordinate metal carbonyl radicals

Walsh diagrams, contour maps, and the atomic character and energies of the frontier molecular Orbitals derived from SCF-Xa-DV calculations have been employed to deduce the most favorable mode of nucleophilic attack at homoleptic metal carbonyl radicals constrained to ideal octahedral, trigonal-bipyramidal, square-pyramidal, and tetrahedral geometries. These studies show that two-center three-elelctron bonding may stabilize a hypervalent 19-electron (19e) transition state or intermediate formed during nucleophilic attack. Spin-polarized calculations suggest a difference between these 19e species and those formed via reduction of saturated, 18e organometallics. For example, little spin density is calculated to delocalize onto the CO ligands when a nucleophile attacks Mn(CO)5 to form a 19e complex. Nucleophilic attack at a face, rather than at an edge of an octahedron, is predicted for the 17e complex V(CO)6. Nucleophilic attack at the open face of the square pyramid is the only mode of attack (of six available) that can be stabilized by two-center three-electron bonding for the square-pyramidal 17e complex Mn(CO)5. Preferred attack at an edge in the equatorial plane is predicted for the trigonal-bipyramidal 17e radical Mn(CO)5. Attack at a tetrahedral face, analogous to SN2 substitution at carbon, is predicted for the tetrahedral 17e species Co(CO)4. © 1988 American Chemical Society.

Authors
Therien, MJ; Trogler, WC
MLA Citation
Therien, MJ, and Trogler, WC. "Theoretical study of bimolecular nucleophilic substitution at four-, five-, and six-coordinate metal carbonyl radicals." Journal of the American Chemical Society 110.15 (1988): 4942-4953.
Source
scival
Published In
Journal of the American Chemical Society
Volume
110
Issue
15
Publish Date
1988
Start Page
4942
End Page
4953

Selective loss of CO in the photochemistry of MnRe(CO)10: a study using matrix isolation and time-resolved infrared spectroscopy

Photolysis of MnRe(CO)10, in argon matrices or room temperature solution, causes dissociation of CO and the formation of a singly bridged intermediate, (CO)4Mn(μ-CO)Re(CO)4. The reaction has been studied using samples specifically enriched with 13CO on the Re end. Careful monitoring, by infrared spectroscopy, of the intensity ratio of 12CO/13/CO of free CO (matrix solution) and of the bridging band of (CO)4Mn(μCO)Re(CO)4 (matrix isolation and time-resolved infrared spectroscopy) show that CO is expelled only from the Mn end of the dimer. There is no evidence for rapid interchange between the bridging CO group and the terminal CO groups on the Mn ends of (CO)4Mn(μ-CO)Re(CO)4. © 1987.

Authors
Firth, S; Hodge, PM; Poliakoff, M; Turner, JJ; Therien, MJ
MLA Citation
Firth, S, Hodge, PM, Poliakoff, M, Turner, JJ, and Therien, MJ. "Selective loss of CO in the photochemistry of MnRe(CO)10: a study using matrix isolation and time-resolved infrared spectroscopy." Journal of Organometallic Chemistry 331.3 (1987): 347-355.
Source
scival
Published In
Journal of Organometallic Chemistry
Volume
331
Issue
3
Publish Date
1987
Start Page
347
End Page
355
DOI
10.1016/0022-328X(87)80007-4

Mechanism of oxidatively induced migratory insertion of carbon monoxide. Evidence for a 19-electron intermediate

The mechanism of oxidatively induced CO insertion for CpFe(CO)(PPh3)CH3 has been probed by transient electrochemical techniques. The data presented herein suggest that the alkyl-to-acyl migration at 17-electron CpFe(CO)-' (PPh3)CH3+ proceeds by a mechanism consisting of two chemical steps. The first step is a second-order process, first order in both the metal radical and entering pyridine nucleophile (Nu), that produced a 19-electron species CpFe(CO)(PPh3)(Nu)CH3+. This complex can be observed directly at low temperature in cyclic voltammetry measurements and in the EPR and IR spectra. The rate of nucleophilic attack at CpFe(CO)(PPh3)CH3+ depends on the σ-basicity of the nitrogen Lewis base as seen from second-order constants, k1, that vary over 5000-fold from 200 (3,4-dimethylpyridine) to 0.04 (3-cyanopyridine) M-1 s-1 at 20°C. Hammett analysis of the rate data shows that log k1 correlates well with the σ-meta and σ-para values for eight 3-and 4-substituted pyridines. The second chemical step that occurs is a nucleophile concentration independent first order process that converts the intermediate CpFe(CO)(PPh3)(Nu)CH3+ to the acyl product, 17-electron CpFe(PPh3)(Nu)(COCH3)+. We rule out a mechanism for the oxidatively induced migratory insertion that proceeds via a 15-electron intermediate, where insertion occurs before nucleophile coordination at CpFe(CO)(PPh3)CH3+. © 1987 American Chemical Society.

Authors
Therien, MJ; Trogler, WC
MLA Citation
Therien, MJ, and Trogler, WC. "Mechanism of oxidatively induced migratory insertion of carbon monoxide. Evidence for a 19-electron intermediate." Journal of the American Chemical Society 109.17 (1987): 5127-5133.
Source
scival
Published In
Journal of the American Chemical Society
Volume
109
Issue
17
Publish Date
1987
Start Page
5127
End Page
5133

Tricarbonylbis(phosphine)iron(I) cation radicals. A spectroscopic and theoretical study

Comparison of the IR spectra of Fe(CO)3(PPh3)2 and the 17-electron complex [Fe(CO)3(PPh3)2][PF6], each enriched 50% and 93% with 13CO, shows that the 17-electron d7 radical retains the trigonal-bipyramidal structure (D3h coordination symmetry) of the parent complex. The IR and EPR spectra of other Fe(CO)3L2+ (L = PMe3, P(n-Bu)3, P(c-C6H11)3) complexes are similar to that of Fe(CO)3(PPh3)2+ with vCO = 1974-1999 cm-1 and (g) = 2.053-2.057 (Ap = 17.5-18.7 G). SCF-Xα-DV calculations for the model complex Fe(CO)3(PH3)2+ of D3h symmetry show a ground-state electronic configuration of 3e″4 (dxz,yz) 6e′3 (dx2-y2,xy). The 3e″ → 6e′ "d-d" transition was calculated to occur at 1.06 eV in the near-IR spectral region and was found at 1.16 eV in the electronic absorption spectrum of [Fe(CO)3(PCy3)2][PF6]. An absorption at 1.89 eV in the spectrum of the latter complex is assigned to the dipole-allowed 5a1′ → 6e′ transition, where 5a1′ is the Fe-P σ-bonding orbital. Calculations for assumed C2v and Cs square-pyramidal isomers of Fe(CO)3(PH3)2+ did not agree with the electronic absorption spectrum of [Fe(CO)3(PCy3)2][PF6]. © 1986 American Chemical Society.

Authors
Therien, MJ; Trogler, WC
MLA Citation
Therien, MJ, and Trogler, WC. "Tricarbonylbis(phosphine)iron(I) cation radicals. A spectroscopic and theoretical study." Journal of the American Chemical Society 108.13 (1986): 3697-3702.
Source
scival
Published In
Journal of the American Chemical Society
Volume
108
Issue
13
Publish Date
1986
Start Page
3697
End Page
3702

Kinetics of disproportionation of tricarbonylbis(phosphine)iron(I) cation radicals probed by double potential step chronocoulometry

Rates of substitution of carbon monoxide in a series of iron(I) radical complexes were measured by using double potential step chronocoulometry, a transient electrochemical technique. Carbon monoxide substitution in Fe(CO)3L2+ (L = a phosphine) radicals proceeds solely by a second-order process that is first order in both the metal radical and the entering pyridine nucleophile. The rate of substitution depends on the basicity and size of the Lewis base, as seen in the L = PPh3 system, where k1 varies over 400-fold from 0.27 to 1.01 × 102 M-1 s-1. Hammett analysis of the rate data shows that log k1 correlates well with the σ-meta and σ-para values for nine 3- and 4-substituted pyridines. Nucleophilic attack of pyridine at Fe(CO)3(PCy3)2+ is 106 times slower than at Fe(CO)3(PMe3)2+, presumably because increased phosphine ligand size inhibits the associative pathway. Activation parameters further support the proposed associative mechanism: for L = PPh3, nucleophile = pyridine, ΔH‡ = 9.8 ± 0.3 kcal mol-1 and ΔS‡ = -21 ± 1 cal mol-1 K-1; for L = PCy3, nucleophile= 3,4-dimethylpyridine, ΔH‡ = 14 ± 1.5 kcal mol-1 and ΔS‡ = -27 ± 5 cal mol-1 K-1. After substitution of carbon monoxide by a nitrogen Lewis base, these complexes disproportionate via an outer-sphere electron-transfer process to yield Fe(II) and Fe(0) products. Comparison of the reactivities of Fe(CO)3(PPh3)2 and its 17-electron analogue, Fe(CO)3(PPh3)2+, shows that the cation radical is about 109 more reactive toward pyridine than its 18-electron precursor. © 1986 American Chemical Society.

Authors
Therien, MJ; Ni, C-L; Anson, FC; Osteryoung, JG; Trogler, WC
MLA Citation
Therien, MJ, Ni, C-L, Anson, FC, Osteryoung, JG, and Trogler, WC. "Kinetics of disproportionation of tricarbonylbis(phosphine)iron(I) cation radicals probed by double potential step chronocoulometry." Journal of the American Chemical Society 108.14 (1986): 4037-4042.
Source
scival
Published In
Journal of the American Chemical Society
Volume
108
Issue
14
Publish Date
1986
Start Page
4037
End Page
4042

Synthesis of amines through nucleophilic addition on nitrogen

Authors
Hagopian, RA; Therien, MJ; Murdoch, JR
MLA Citation
Hagopian, RA, Therien, MJ, and Murdoch, JR. "Synthesis of amines through nucleophilic addition on nitrogen." Journal of the American Chemical Society 106.19 (1984): 5753-5754.
Source
scival
Published In
Journal of the American Chemical Society
Volume
106
Issue
19
Publish Date
1984
Start Page
5753
End Page
5754
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