1
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Freixas VM, Keefer D, Tretiak S, Fernandez-Alberti S, Mukamel S. Ultrafast coherent photoexcited dynamics in a trimeric dendrimer probed by X-ray stimulated-Raman signals. Chem Sci 2022; 13:6373-6384. [PMID: 35733898 PMCID: PMC9159119 DOI: 10.1039/d2sc00601d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/11/2022] [Indexed: 12/14/2022] Open
Abstract
The photoinduced ultrafast coherent inter-chromophore energy redistribution in a triarylamine trimer is explored using nonadiabatic excited state molecular dynamics followed by simulations of X-ray Raman signals. The nitrogencentered system ensures strong interchromophore interactions and, thus, the presence of coherences. Nevertheless, the multitude of non-deterministic photoinduced pathways during the ultrafast inter-branch migration of the excitation results in random confinement on some branches and, therefore, spatial exciton scrambling and loss of phase information at long times. We show that the vibronic coherence dynamics evolving into the incoherent scrambling mechanism on ultrafast 50 fs timescale, is accurately probed by the TRUECARS X-ray stimulated Raman signal. In combination with previous results, where the technique has revealed long-lived coherences in a rigid heterodimer, the signal is most valuable for detecting ultrafast molecular coherences or their absence. We demonstrate that X-ray Raman spectroscopy is a useful tool in the chemical design of functional molecular building blocks. The photoinduced ultrafast coherent inter-chromophore energy redistribution in a triarylamine trimer is explored using nonadiabatic excited state molecular dynamics followed by simulations of X-ray Raman signals.![]()
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Affiliation(s)
- Victor M Freixas
- Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes/CONICET B1876BXD Bernal Argentina
| | - Daniel Keefer
- Department of Chemistry and Physics and Astronomy, University of California Irvine California 92697-2025 USA
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory Los Alamos New Mexico 87545 USA
| | | | - Shaul Mukamel
- Department of Chemistry and Physics and Astronomy, University of California Irvine California 92697-2025 USA
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2
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Bonardd S, Díaz Díaz D, Leiva A, Saldías C. Chromophoric Dendrimer-Based Materials: An Overview of Holistic-Integrated Molecular Systems for Fluorescence Resonance Energy Transfer (FRET) Phenomenon. Polymers (Basel) 2021; 13:4404. [PMID: 34960954 PMCID: PMC8705239 DOI: 10.3390/polym13244404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 12/15/2022] Open
Abstract
Dendrimers (from the Greek dendros → tree; meros → part) are macromolecules with well-defined three-dimensional and tree-like structures. Remarkably, this hyperbranched architecture is one of the most ubiquitous, prolific, and recognizable natural patterns observed in nature. The rational design and the synthesis of highly functionalized architectures have been motivated by the need to mimic synthetic and natural-light-induced energy processes. Dendrimers offer an attractive material scaffold to generate innovative, technological, and functional materials because they provide a high amount of peripherally functional groups and void nanoreservoirs. Therefore, dendrimers emerge as excellent candidates since they can play a highly relevant role as unimolecular reactors at the nanoscale, acting as versatile and sophisticated entities. In particular, they can play a key role in the properties of light-energy harvesting and non-radiative energy transfer, allowing them to function as a whole unit. Remarkably, it is possible to promote the occurrence of the FRET phenomenon to concentrate the absorbed energy in photoactive centers. Finally, we think an in-depth understanding of this mechanism allows for diverse and prolific technological applications, such as imaging, biomedical therapy, and the conversion and storage of light energy, among others.
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Affiliation(s)
- Sebastián Bonardd
- Departamento de Química Orgánica, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez S/N, La Laguna, 38206 Tenerife, Spain; (S.B.); (D.D.D.)
- Instituto Universitario de Bio-Orgánica Antonio González, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez 2, La Laguna, 38206 Tenerife, Spain
| | - David Díaz Díaz
- Departamento de Química Orgánica, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez S/N, La Laguna, 38206 Tenerife, Spain; (S.B.); (D.D.D.)
- Instituto Universitario de Bio-Orgánica Antonio González, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez 2, La Laguna, 38206 Tenerife, Spain
- Institutfür Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Angel Leiva
- Departamento de Química Física, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Macul, Santiago, CL 7820436, USA;
| | - César Saldías
- Departamento de Química Física, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Macul, Santiago, CL 7820436, USA;
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3
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Seintis K, Kalis IK, Klikar M, Bureš F, Fakis M. Excitation/detection energy controlled anisotropy dynamics in asymmetrically cyano substituted tri-podal molecules. Phys Chem Chem Phys 2020; 22:16681-16690. [PMID: 32658218 DOI: 10.1039/d0cp01726d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present work, the photophysical properties of two series of asymmetrical tri-podal molecules are studied, in order to determine the dependence of energy localization/delocalization phenomena on excitation and detection wavelength, by means of steady state, femtosecond time-resolved fluorescence and anisotropy spectroscopy. The molecules bear triphenylamine as an electron donating core and an acetylenic or olefinic π-conjugated bridge. At the periphery, they are substituted by no, one, two or three -CN groups used as electron acceptors. Thus, the compounds with only one or two -CN groups are asymmetrically substituted. As a comparison, the photophysics of their dipolar and quadrupolar analogues is also presented. The steady state absorption spectra of the asymmetrical tri-podal compounds exhibit a broadening and a low energy shoulder due to the splitting of the excited states. The fluorescence spectra are more red-shifted in the tri-podal molecules with a single -CN group, providing the first evidence of its mostly dipolar nature. Time-resolved anisotropy measurements by using different excitation and detection wavelengths provide clear evidence that the asymmetrical tri-podal molecules with one or two -CN groups behave like octupolar molecules upon high-energy excitation (the initial anisotropy is found 0.1-0.15), while upon low-energy excitation they reveal a behavior expected for linear dipolar or V-shaped quadrupolar molecules (the initial anisotropy is very close to 0.4 and 0.17, respectively). The symmetrical tri-podal compounds with no or three cyano groups, exhibit an anisotropy depolarization time of 2.5 ps attributed to energy hopping. The amplitude of this energy hopping component is wavelength dependent and increases as the excitation is shifted towards the long wavelength edge.
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Affiliation(s)
- K Seintis
- Department of Physics, University of Patras, GR-26504, Patras, Greece.
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4
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Nelson TR, White AJ, Bjorgaard JA, Sifain AE, Zhang Y, Nebgen B, Fernandez-Alberti S, Mozyrsky D, Roitberg AE, Tretiak S. Non-adiabatic Excited-State Molecular Dynamics: Theory and Applications for Modeling Photophysics in Extended Molecular Materials. Chem Rev 2020; 120:2215-2287. [PMID: 32040312 DOI: 10.1021/acs.chemrev.9b00447] [Citation(s) in RCA: 220] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Optically active molecular materials, such as organic conjugated polymers and biological systems, are characterized by strong coupling between electronic and vibrational degrees of freedom. Typically, simulations must go beyond the Born-Oppenheimer approximation to account for non-adiabatic coupling between excited states. Indeed, non-adiabatic dynamics is commonly associated with exciton dynamics and photophysics involving charge and energy transfer, as well as exciton dissociation and charge recombination. Understanding the photoinduced dynamics in such materials is vital to providing an accurate description of exciton formation, evolution, and decay. This interdisciplinary field has matured significantly over the past decades. Formulation of new theoretical frameworks, development of more efficient and accurate computational algorithms, and evolution of high-performance computer hardware has extended these simulations to very large molecular systems with hundreds of atoms, including numerous studies of organic semiconductors and biomolecules. In this Review, we will describe recent theoretical advances including treatment of electronic decoherence in surface-hopping methods, the role of solvent effects, trivial unavoided crossings, analysis of data based on transition densities, and efficient computational implementations of these numerical methods. We also emphasize newly developed semiclassical approaches, based on the Gaussian approximation, which retain phase and width information to account for significant decoherence and interference effects while maintaining the high efficiency of surface-hopping approaches. The above developments have been employed to successfully describe photophysics in a variety of molecular materials.
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Affiliation(s)
- Tammie R Nelson
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Alexander J White
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Josiah A Bjorgaard
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Andrew E Sifain
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States.,U.S. Army Research Laboratory , Aberdeen Proving Ground , Maryland 21005 , United States
| | - Yu Zhang
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Benjamin Nebgen
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | | | - Dmitry Mozyrsky
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Adrian E Roitberg
- Department of Chemistry , University of Florida , Gainesville , Florida 32611 , United States
| | - Sergei Tretiak
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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5
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Garay RO, Del Rosso PG, Romagnoli MJ, Almassio MF, Schvval AB. Photoactive thin films of terphenylene-based amorphous polymers. Synthesis, electrooptical properties, and role of photoquenching and inner filter effects in the chemosensing of nitroaromatics. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2019.112016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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6
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Ondarse-Alvarez D, Nelson T, Lupton JM, Tretiak S, Fernandez-Alberti S. Let Digons be Bygones: The Fate of Excitons in Curved π-Systems. J Phys Chem Lett 2018; 9:7123-7129. [PMID: 30508376 DOI: 10.1021/acs.jpclett.8b03160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We explore the diverse origins of unpolarized absorption and emission of molecular polygons consisting of π-conjugated oligomer chains held in a bent geometry by strain controlled at the vertex units. For this purpose, we make use of atomistic nonadiabatic excited-state molecular dynamics simulations of a bichromophore molecular polygon (digon) with bent chromophore chains. Both structural and photoexcited dynamics were found to affect polarization features. Bending strain induces exciton localization on individual chromophore units of the conjugated chains. The latter display different transition dipole moment orientations, a feature not present in the linear oligomer counterparts. In addition, bending makes exciton localization very sensitive to molecular distortions induced by thermal fluctuations. The excited-state dynamics reveals an ultrafast intramolecular energy redistribution that spreads the exciton equally among spatially separated chromophore fragments within the molecular system. As a result, digons become virtually unpolarized absorbers and emitters, in agreement with recent experimental studies on the single-molecule level.
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Affiliation(s)
| | - Tammie Nelson
- Theoretical Division, Physics and Chemistry of Materials (T-1) , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - John M Lupton
- Institut für Angewandte und Experimentelle Physik , Universität Regensburg , Universitätsstrasse 31 , 93053 Regensburg , Germany
| | - Sergei Tretiak
- Theoretical Division, Physics and Chemistry of Materials (T-1) , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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7
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Abd-El-Aziz AS, Abdelghani AA, Wagner BD, Bissessur R. Advances in Light-Emitting Dendrimers. Macromol Rapid Commun 2018; 40:e1800711. [DOI: 10.1002/marc.201800711] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 10/30/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Alaa S. Abd-El-Aziz
- Department of Chemistry; University of Prince Edward Island; 550 University Avenue Charlottetown Prince Edward Island C1A 4P3 Canada
| | - Amani A. Abdelghani
- Department of Chemistry; University of Prince Edward Island; 550 University Avenue Charlottetown Prince Edward Island C1A 4P3 Canada
| | - Brian D. Wagner
- Department of Chemistry; University of Prince Edward Island; 550 University Avenue Charlottetown Prince Edward Island C1A 4P3 Canada
| | - Rabin Bissessur
- Department of Chemistry; University of Prince Edward Island; 550 University Avenue Charlottetown Prince Edward Island C1A 4P3 Canada
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8
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Taylor EL, Metcalf KJ, Carlotti B, Lai CT, Modica JA, Schatz GC, Mrksich M, Goodson T. Long-Range Energy Transfer in Protein Megamolecules. J Am Chem Soc 2018; 140:15731-15743. [PMID: 30375862 PMCID: PMC6710013 DOI: 10.1021/jacs.8b08208] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this investigation, we report evidence for energy transfer in new protein-based megamolecules with tunable distances between donor and acceptor fluorescent proteins. The megamolecules used in this work are monodisperse oligomers, with molecular weights of ∼100-300 kDa and lengths of ∼5-20 nm, and are precisely defined structures of fusion protein building blocks and covalent cross-linkers. Such structures are promising because the study of energy transfer in protein complexes is usually difficult in this long length regime due to synthetic limitations. We incorporated fluorescent proteins into the megamolecule structure and varied the separation distance between donor and acceptor by changing the length of the cross-linker in dimer conjugates and inserting nonfluorescent spacer proteins to create oligomers. Two-photon absorption measurements demonstrated strong coupling between donor and acceptor dipoles in the megamolecules. For the dimer systems, no effect of the cross-linker length on energy transfer efficiency was observed with the steady-state fluorescence investigation. However, for the same dimer conjugates, energy transfer rates decreased upon increasing cross-linker length, as evaluated by fluorescence up-conversion. Molecular dynamics simulations were used to rationalize the results, providing quantitative agreement between measured and calculated energy transfer lengths for steady-state results, and showing that the differences between the time-resolved and steady-state measurements arise from the long time scale for large-scale fluctuations in the megamolecule structure. Our results show an increase in energy transfer length with increasing megamolecule size. This is evidence for long-range energy transfer in large protein megamolecules.
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Affiliation(s)
- Elijah L. Taylor
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kevin J. Metcalf
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Benedetta Carlotti
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia 06123, Italy
| | - Cheng-Tsung Lai
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Justin A. Modica
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - George C. Schatz
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Milan Mrksich
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Theodore Goodson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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9
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Ziessel R, Stachelek P, Harriman A, Hedley GJ, Roland T, Ruseckas A, Samuel IDW. Ultrafast Through-Space Electronic Energy Transfer in Molecular Dyads Built around Dynamic Spacer Units. J Phys Chem A 2018; 122:4437-4447. [DOI: 10.1021/acs.jpca.8b02415] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Raymond Ziessel
- Molecular Photonics Laboratory, School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Patrycja Stachelek
- Molecular Photonics Laboratory, School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Anthony Harriman
- Molecular Photonics Laboratory, School of Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Gordon J. Hedley
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, Physical Science Building, University of St. Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - Thomas Roland
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, Physical Science Building, University of St. Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, Physical Science Building, University of St. Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, Physical Science Building, University of St. Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
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10
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Klikar M, Seintis K, Polyzos I, Pytela O, Mikysek T, Almonasy N, Fakis M, Bureš F. Star-Shaped Push-Pull Molecules with a Varied Number of Peripheral Acceptors: An Insight into Their Optoelectronic Features. CHEMPHOTOCHEM 2018. [DOI: 10.1002/cptc.201800051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Milan Klikar
- Institute of Organic Chemistry and Technology; Faculty of Chemical Technology, University of Pardubice; Studentská 573 Pardubice 532 10 Czech Republic
| | - Kostas Seintis
- Department of Physics; University of Patras; GR-26504 Patras Greece
| | - Ioannis Polyzos
- Department of Physics; University of Patras; GR-26504 Patras Greece
- Foundation of Research and Technology Hellas; Institute of Chemical Engineering Sciences (FORTH/ICE-HT); Stadiou Str. P.O. Box 1414 Rio-Patras Greece
| | - Oldřich Pytela
- Institute of Organic Chemistry and Technology; Faculty of Chemical Technology, University of Pardubice; Studentská 573 Pardubice 532 10 Czech Republic
| | - Tomáš Mikysek
- Department of Analytical Chemistry, Faculty of Chemical Technology; University of Pardubice; Studentská 573 Pardubice 53210 Czech Republic
| | - Numan Almonasy
- Institute of Organic Chemistry and Technology; Faculty of Chemical Technology, University of Pardubice; Studentská 573 Pardubice 532 10 Czech Republic
| | - Mihalis Fakis
- Department of Physics; University of Patras; GR-26504 Patras Greece
| | - Filip Bureš
- Institute of Organic Chemistry and Technology; Faculty of Chemical Technology, University of Pardubice; Studentská 573 Pardubice 532 10 Czech Republic
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11
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Ondarse-Alvarez D, Oldani N, Roitberg AE, Kleiman V, Tretiak S, Fernandez-Alberti S. Energy transfer and spatial scrambling of an exciton in a conjugated dendrimer. Phys Chem Chem Phys 2018; 20:29648-29660. [DOI: 10.1039/c8cp05852k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoexcitation of multichromophoric light harvesting molecules induces a number of intramolecular electronic energy relaxation and redistribution pathways that can ultimately lead to ultrafast exciton self-trapping on a single chromophore unit.
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Affiliation(s)
- D. Ondarse-Alvarez
- Departamento de Ciencia y Tecnologia
- Universidad Nacional de Quilmes/CONICET
- B1876BXD Bernal
- Argentina
| | - N. Oldani
- Departamento de Ciencia y Tecnologia
- Universidad Nacional de Quilmes/CONICET
- B1876BXD Bernal
- Argentina
| | - A. E. Roitberg
- Department of Chemistry of Chemistry
- University of Florida
- Gainesville
- USA
| | - V. Kleiman
- Department of Chemistry of Chemistry
- University of Florida
- Gainesville
- USA
| | - S. Tretiak
- Theoretical Division
- Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT)
- Los Alamos National Laboratory
- Los Alamos
- USA
| | - S. Fernandez-Alberti
- Departamento de Ciencia y Tecnologia
- Universidad Nacional de Quilmes/CONICET
- B1876BXD Bernal
- Argentina
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12
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Nelson T, Fernandez-Alberti S, Roitberg AE, Tretiak S. Electronic Delocalization, Vibrational Dynamics, and Energy Transfer in Organic Chromophores. J Phys Chem Lett 2017; 8:3020-3031. [PMID: 28603994 DOI: 10.1021/acs.jpclett.7b00790] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The efficiency of materials developed for solar energy and technological applications depends on the interplay between molecular architecture and light-induced electronic energy redistribution. The spatial localization of electronic excitations is very sensitive to molecular distortions. Vibrational nuclear motions can couple to electronic dynamics driving changes in localization. The electronic energy transfer among multiple chromophores arises from several distinct mechanisms that can give rise to experimentally measured signals. Atomistic simulations of coupled electron-vibrational dynamics can help uncover the nuclear motions directing energy flow. Through careful analysis of excited state wave function evolution and a useful fragmenting of multichromophore systems, through-bond transport and exciton hopping (through-space) mechanisms can be distinguished. Such insights are crucial in the interpretation of fluorescence anisotropy measurements and can aid materials design. This Perspective highlights the interconnected vibrational and electronic motions at the foundation of nonadiabatic dynamics where nuclear motions, including torsional rotations and bond vibrations, drive electronic transitions.
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Affiliation(s)
- Tammie Nelson
- Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | | | - Adrian E Roitberg
- Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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13
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Cho YJ, Kim SY, Son MR, Son HJ, Cho DW, Kang SO. Time-resolved spectroscopic analysis of the light-energy harvesting mechanism in carbazole-dendrimers with a blue-phosphorescent Ir-complex core. Phys Chem Chem Phys 2017; 19:20093-20100. [DOI: 10.1039/c7cp01989k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In order to understand the light energy-harvesting mechanism, singular value decomposition analysis was performed to classify the temporal and spectral species in transient absorption spectra.
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Affiliation(s)
- Yang-Jin Cho
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
| | - So-Yoen Kim
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
| | - Mi Rang Son
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
| | - Ho-Jin Son
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
| | - Dae Won Cho
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
- Center for Photovoltaic Materials
| | - Sang Ook Kang
- Department of Advanced Materials Chemistry
- Korea University (Sejong)
- Sejong
- South Korea
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14
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Seintis K, Agathangelou D, Cvejn D, Almonasy N, Bureš F, Giannetas V, Fakis M. Femtosecond to nanosecond studies of octupolar molecules and their quadrupolar and dipolar analogues. Phys Chem Chem Phys 2017; 19:16485-16497. [DOI: 10.1039/c7cp01463e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The fs–ps anisotropy dynamics of octupolar, quadrupolar and dipolar molecules with different π-bridges.
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Affiliation(s)
- K. Seintis
- Department of Physics
- University of Patras
- Patras
- Greece
| | | | - D. Cvejn
- Institute of Organic Chemistry and Technology
- Faculty of Chemical Technology
- University of Pardubice
- Pardubice
- Czech Republic
| | - N. Almonasy
- Institute of Organic Chemistry and Technology
- Faculty of Chemical Technology
- University of Pardubice
- Pardubice
- Czech Republic
| | - F. Bureš
- Institute of Organic Chemistry and Technology
- Faculty of Chemical Technology
- University of Pardubice
- Pardubice
- Czech Republic
| | - V. Giannetas
- Department of Physics
- University of Patras
- Patras
- Greece
| | - M. Fakis
- Department of Physics
- University of Patras
- Patras
- Greece
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15
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Abstract
![]()
The field of organic
photovoltaics has developed rapidly over the
last 2 decades, and small solar cells with power conversion efficiencies
of 13% have been demonstrated. Light absorbed in the organic layers
forms tightly bound excitons that are split into free electrons and
holes using heterojunctions of electron donor and acceptor materials,
which are then extracted at electrodes to give useful electrical power.
This review gives a concise description of the fundamental processes
in photovoltaic devices, with the main emphasis on the characterization
of energy transfer and its role in dictating device architecture,
including multilayer planar heterojunctions, and on the factors that
impact free carrier generation from dissociated excitons. We briefly
discuss harvesting of triplet excitons, which now attracts substantial
interest when used in conjunction with singlet fission. Finally, we
introduce the techniques used by researchers for characterization
and engineering of bulk heterojunctions to realize large photocurrents,
and examine the formed morphology in three prototypical blends.
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Affiliation(s)
- Gordon J Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
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16
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He G, Yu C, Li Y, Hu J, Liu Z, Zhang D, Guo Q, Xia A. Excitation Energy Transfer inmeta-Substituted Phenylacetylene Multibranched Chromophores. Chem Asian J 2016; 11:2741-2748. [DOI: 10.1002/asia.201600326] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/06/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Guiying He
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
- University of Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Chenmin Yu
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Laboratory of Organic Solid; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
- University of Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Yang Li
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
- University of Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Jiangpu Hu
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
- University of Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Zitong Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Laboratory of Organic Solid; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
| | - Deqing Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Laboratory of Organic Solid; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
| | - Qianjin Guo
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
| | - Andong Xia
- Beijing National Laboratory for Molecular Sciences (BNLMS) and; Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P.R. China
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17
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Griffin GB, Lundin PM, Rolczynski BS, Linkin A, McGillicuddy RD, Bao Z, Engel GS. Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer. J Chem Phys 2015; 140:034903. [PMID: 25669410 DOI: 10.1063/1.4855156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ∼250 fs.
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Affiliation(s)
- Graham B Griffin
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Pamela M Lundin
- Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305, USA
| | - Brian S Rolczynski
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Alexander Linkin
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Ryan D McGillicuddy
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stauffer III, 381 North-South Mall, Stanford, California 94305, USA
| | - Gregory S Engel
- Department of Chemistry, The James Franck Institute, Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
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18
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Li Y, Zhou M, Niu Y, Guo Q, Xia A. Solvent-dependent intramolecular charge transfer delocalization/localization in multibranched push-pull chromophores. J Chem Phys 2015. [DOI: 10.1063/1.4926998] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yang Li
- Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Meng Zhou
- Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Yingli Niu
- Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Qianjin Guo
- Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Andong Xia
- Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
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19
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Koda SI. Equivalence between a generalized dendritic network and a set of one-dimensional networks as a ground of linear dynamics. J Chem Phys 2015; 142:204112. [PMID: 26026439 DOI: 10.1063/1.4921730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
It has been shown by some existing studies that some linear dynamical systems defined on a dendritic network are equivalent to those defined on a set of one-dimensional networks in special cases and this transformation to the simple picture, which we call linear chain (LC) decomposition, has a significant advantage in understanding properties of dendrimers. In this paper, we expand the class of LC decomposable system with some generalizations. In addition, we propose two general sufficient conditions for LC decomposability with a procedure to systematically realize the LC decomposition. Some examples of LC decomposable linear dynamical systems are also presented with their graphs. The generalization of the LC decomposition is implemented in the following three aspects: (i) the type of linear operators; (ii) the shape of dendritic networks on which linear operators are defined; and (iii) the type of symmetry operations representing the symmetry of the systems. In the generalization (iii), symmetry groups that represent the symmetry of dendritic systems are defined. The LC decomposition is realized by changing the basis of a linear operator defined on a dendritic network into bases of irreducible representations of the symmetry group. The achievement of this paper makes it easier to utilize the LC decomposition in various cases. This may lead to a further understanding of the relation between structure and functions of dendrimers in future studies.
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Affiliation(s)
- Shin-ichi Koda
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan
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20
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Adegoke OO, Jung IH, Orr M, Yu L, Goodson T. Effect of Acceptor Strength on Optical and Electronic Properties in Conjugated Polymers for Solar Applications. J Am Chem Soc 2015; 137:5759-69. [DOI: 10.1021/ja513002h] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Oluwasegun O. Adegoke
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - In Hwan Jung
- Department
of Chemistry and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Meghan Orr
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Luping Yu
- Department
of Chemistry and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Theodore Goodson
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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21
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Cho YJ, Hong SA, Son HJ, Han WS, Cho DW, Kang SO. Efficient Light Harvesting and Energy Transfer in a Red Phosphorescent Iridium Dendrimer. Inorg Chem 2014; 53:13136-41. [DOI: 10.1021/ic502323w] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Yang-Jin Cho
- Department
of Advanced Materials Chemistry, Korea University, Sejong 339-700, South Korea
| | - Seong Ahn Hong
- Department
of Advanced Materials Chemistry, Korea University, Sejong 339-700, South Korea
| | - Ho-Jin Son
- Department
of Advanced Materials Chemistry, Korea University, Sejong 339-700, South Korea
| | - Won-Sik Han
- Department of Chemistry, Seoul Women’s University, Seoul 139-774, South Korea
| | - Dae Won Cho
- Department
of Advanced Materials Chemistry, Korea University, Sejong 339-700, South Korea
| | - Sang Ook Kang
- Department
of Advanced Materials Chemistry, Korea University, Sejong 339-700, South Korea
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22
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Liu Z, Xiao J, Fu Q, Feng H, Zhang X, Ren T, Wang S, Ma D, Wang X, Chen H. Synthesis and physical properties of the conjugated dendrons bearing twisted acenes used in solution processing of organic light-emitting diodes. ACS APPLIED MATERIALS & INTERFACES 2013; 5:11136-11141. [PMID: 24144121 DOI: 10.1021/am403394k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Five novel organic conjugated derivatives containing multifraction twisted acene units have been synthesized and characterized. These compounds and the model molecule 2-methyl-5,12-diphenyl-6:7,10:11-bisbenzotetracene emit strong blue light in diluted solution with quantum yields of 0.21-0.67, while in the solid state, except for the 1,2,3,4,5,6-hexa(2-(5,12-diphenyl-6:7,10:11-bis(4'-tert-butylbenzo)tetracene))benzene, green luminance is seen. The experimental results also indicate that the multifraction structure leads to a significant fluorescence enhancement (over two times) compared to the monomer, which might be attributed to the formation of delocalized excited state in multibranch structures. The quantum-chemical calculation implies that only two branches are involved in formation of the delocalized system for the multibranched derivatives. Furthermore, the organic light-emitting diode (OLED) devices using compounds 1,4-di(2-(5,12-diphenyl-6:7,10:11-bis(4'-tert-butylbenzo)tetracene))benzene, 1,3-di(2-(5,12-diphenyl-6:7,10:11-bis(4'-tert-butylbenzo)tetracene))benzene, and 1,3,5-tri(2-(5,12-diphenyl-6:7,10:11-bis(4'-tert-butylbenzo)tetracene))benzene as emitters exhibit good electroluminescent performance. Our systematic studies might provide more chances to challenge the rational design and synthesis of new- and high-generation branched dendrimers.
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Affiliation(s)
- Zhenying Liu
- College of Chemistry and Environment Science, Key Laboratory of Chemical Biology of Hebei Province, Hebei University , Baoding 071002, P. R. China
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23
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Liu C, Tang KC, Zhang H, Pan HA, Hua J, Li B, Chou PT. Studies of Excited-State Properties of Multibranched Triarylamine End-Capped Triazines. J Phys Chem A 2012. [DOI: 10.1021/jp310711e] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chun Liu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan. R.
O. C
| | - Kuo-Chun Tang
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan. R.
O. C
| | - Hao Zhang
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
| | - Hsiao-An Pan
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan. R.
O. C
| | - Jianli Hua
- Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China
| | - Bo Li
- Key Laboratory
of Polar Materials
and Devices, Ministry of Education, East China Normal University, Shanghai 200241, P. R. China
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan. R.
O. C
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24
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Zhang J, Fischer MKR, Bäuerle P, Goodson T. Energy Migration in Dendritic Oligothiophene-Perylene Bisimides. J Phys Chem B 2012; 117:4204-15. [DOI: 10.1021/jp302772y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
| | - Markus K. R. Fischer
- Institute of Organic Chemistry
II and Advanced Materials, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Peter Bäuerle
- Institute of Organic Chemistry
II and Advanced Materials, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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25
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Montgomery NA, Hedley GJ, Ruseckas A, Denis JC, Schumacher S, Kanibolotsky AL, Skabara PJ, Galbraith I, Turnbull GA, Samuel IDW. Dynamics of fluorescence depolarisation in star-shaped oligofluorene-truxene molecules. Phys Chem Chem Phys 2012; 14:9176-84. [PMID: 22641238 DOI: 10.1039/c2cp24141b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Star-shaped molecules are of growing interest as organic optoelectronic materials. Here a detailed study of their photophysics using fluorescence depolarisation is reported. Fluorescence depolarisation dynamics are studied in branched oligofluorene-truxene molecules with a truxene core and well-defined three-fold symmetry, and are compared with linear fluorene oligomers. An initial anisotropy value of 0.4 is observed which shows a two-exponential decay with time constants of 500 fs and 3-8 ps in addition to a long-lived component. The femtosecond component is attributed to exciton localisation on one branch of the molecule and its amplitude reduces when the excitation is tuned to the low energy tail of the absorption spectrum. The picosecond component shows a weak dependence on the excitation wavelength and is similar to the calculated rate of the resonant energy transfer of the localised exciton between the branches. These assignments are supported by density-functional theory calculations which show a disorder-induced splitting of the two degenerate excited states. Exciton localisation is much slower than previously reported in other branched molecules which suggests that efficient light-harvesting systems can be designed using oligofluorenes and truxenes as building blocks.
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Affiliation(s)
- Neil A Montgomery
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, United Kingdom
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26
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Mechanisms of Light Energy Harvesting in Dendrimers and Hyperbranched Polymers. Polymers (Basel) 2011. [DOI: 10.3390/polym3042053] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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27
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Olaya-Castro A, Scholes GD. Energy transfer from Förster–Dexter theory to quantum coherent light-harvesting. INT REV PHYS CHEM 2011. [DOI: 10.1080/0144235x.2010.537060] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Badaeva E, Harpham MR, Guda R, Süzer Ö, Ma CQ, Bäuerle P, Goodson T, Tretiak S. Excited-State Structure of Oligothiophene Dendrimers: Computational and Experimental Study. J Phys Chem B 2010; 114:15808-17. [DOI: 10.1021/jp109624d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ekaterina Badaeva
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Michael R. Harpham
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ramakrishna Guda
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Özgün Süzer
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Chang-Qi Ma
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Peter Bäuerle
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Theodore Goodson
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergei Tretiak
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States, Department of Chemistry, Applied Physics Program, The University of Michigan, Ann Arbor Michigan 48109, United States, Institute of Organic Chemistry II and Advanced Materials, University of Ulm, 89081, Ulm, Germany, and Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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29
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Oh MHJ, Salvador MR, Wong CY, Scholes GD. Three-Pulse Photon-Echo Peak Shift Spectroscopy and Its Application for the Study of Solvation and Nanoscale Excitons. Chemphyschem 2010; 12:88-100. [DOI: 10.1002/cphc.201000712] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Indexed: 11/10/2022]
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30
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Benincori T, Bonometti V, De Angelis F, Falciola L, Muccini M, Mussini P, Pilati T, Rampinini G, Rizzo S, Toffanin S, Sannicolò F. Towards Molecular Design Rationalization in Branched Multi-Thiophene Semiconductors: The 2-Thienyl-Persubstituted α-Oligothiophenes. Chemistry 2010; 16:9086-98. [DOI: 10.1002/chem.200903546] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Jia M, Ma X, Yan L, Wang H, Guo Q, Wang X, Wang Y, Zhan X, Xia A. Photophysical Properties of Intramolecular Charge Transfer in Two Newly Synthesized Tribranched Donor−π−Acceptor Chromophores. J Phys Chem A 2010; 114:7345-52. [DOI: 10.1021/jp1032355] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mingli Jia
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Xiaonan Ma
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Linyin Yan
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Haifeng Wang
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Qianjin Guo
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Xuefei Wang
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Yingying Wang
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Xiaowei Zhan
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Andong Xia
- The State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, The CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
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32
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Guo M, Varnavski O, Narayanan A, Mongin O, Majoral JP, Blanchard-Desce M, Goodson T. Investigations of energy migration in an organic dendrimer macromolecule for sensory signal amplification. J Phys Chem A 2009; 113:4763-71. [PMID: 19317441 DOI: 10.1021/jp8112123] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The issue of macromolecular exciton delocalization length and fluorescence sensing of energetic materials is investigated and modeled from results of nonlinear optical and time-resolved spectroscopy. By using two- and three-photon absorption techniques the fluorescence quenching effects of an organic dendrimer for sensing TNT were carried out. The Stern-Volmer plots for the set of dendrimers were examined and a large quenching constant for the dendrimer G4 was obtained (1400 M(-1)). The quenching constant was found to increase with the dendrimer generation number. The mechanism for the enhanced sensitivity of the dendrimer system was examined by probing the exciton dynamics with femtosecond fluorescence up-conversion. Fluorescence lifetime measurements revealed a multicomponent relaxation that varied with dendrimer generation. Fluorescence anisotropy decay measurements were used to probe the exciton migration length in these dendrimer systems and for the large structure the excitation migration area covers approximately 20 units. All of these results were used in a model that describes the exciton localization length with the fluorescence quenching strength. The use of time-resolved techniques allows for a closer and more detailed description of the mechanism of sensory amplification in organic macromolecules.
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Affiliation(s)
- Meng Guo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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33
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Collini E, Scholes GD. Electronic and Vibrational Coherences in Resonance Energy Transfer along MEH-PPV Chains at Room Temperature. J Phys Chem A 2009; 113:4223-41. [DOI: 10.1021/jp810757x] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Elisabetta Collini
- Lash-Miller Chemical Laboratories, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Gregory D. Scholes
- Lash-Miller Chemical Laboratories, Institute for Optical Sciences and Centre for Quantum Information and Quantum Control, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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34
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Mechanism of Förster-type hopping of charge transfer and excitation energy transfer along blocked oligothiophenes by Si-atoms. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Ribierre JC, Ruseckas A, Samuel IDW, Barcena HS, Burn PL. Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers. J Chem Phys 2008; 128:204703. [DOI: 10.1063/1.2919567] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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He GS, Tan LS, Zheng Q, Prasad PN. Multiphoton Absorbing Materials: Molecular Designs, Characterizations, and Applications. Chem Rev 2008; 108:1245-330. [PMID: 18361528 DOI: 10.1021/cr050054x] [Citation(s) in RCA: 1211] [Impact Index Per Article: 75.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ramakrishna G, Bhaskar A, Bauerle P, Goodson T. Oligothiophene Dendrimers as New Building Blocks for Optical Applications. J Phys Chem A 2007; 112:2018-26. [DOI: 10.1021/jp076048h] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Guda Ramakrishna
- Department of Chemistry and Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, and Department of Organic Chemistry II, Ulm University, 89081 Ulm, Germany
| | - Ajit Bhaskar
- Department of Chemistry and Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, and Department of Organic Chemistry II, Ulm University, 89081 Ulm, Germany
| | - Peter Bauerle
- Department of Chemistry and Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, and Department of Organic Chemistry II, Ulm University, 89081 Ulm, Germany
| | - Theodore Goodson
- Department of Chemistry and Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, and Department of Organic Chemistry II, Ulm University, 89081 Ulm, Germany
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Saab MA, Abdel-Malak R, Wishart JF, Ghaddar TH. Photocurrent generation in layer-by-layer assembled dendrimers with ruthenium tris-bipyridine peripheral groups and a viologen-like core. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:10807-15. [PMID: 17877379 DOI: 10.1021/la701574j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The photophysical and photoelectrochemical properties of first- and second-generation dendrimers with ruthenium tris-bipyridine peripheral groups and a tri-viologen like core (Ru3V3 and Ru6V3) were investigated in solution and when embedded within assembled films. The stepwise assembly of these dendrimers on quartz and ITO surfaces utilizing the layer-by-layer approach was investigated. The amount of the assembled dendrimers was found to increase on going to the higher generation dendrimer. This dendrimer generation effect was evident from the UV-vis, atomic force microscopy, and electrochemical measurements of the dendrimers in either solution phase or when embedded in films. The anodic and cathodic photocurrent generation was seen upon visible light irradiation, with higher photocurrents for Ru6V3 than Ru3V3. This observation was attributed to better light-harvesting properties, thicker films, and slower charge recombination processes in Ru6V3 when compared to Ru3V3.
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Affiliation(s)
- Manal Abi Saab
- Department of Chemistry, American University of Beirut, Beirut 11-0236, Lebanon
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Larsen J, Brüggemann B, Khoury T, Sly J, Crossley MJ, Sundström V, Akesson E. Structural Induced Control of Energy Transfer within Zn(II)−Porphyrin Dendrimers. J Phys Chem A 2007; 111:10589-97. [PMID: 17914756 DOI: 10.1021/jp070545g] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For the largest dendrimer having 64 Zn(II)-porphyrins, only approximately 10% of the excitation intensity is needed in order to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting chain as compared to those without. Complete annihilation, until only one chromophore remains excited, now occurs within subunits of seven chromophores, when half of the chromophores are excited. The improvement of the annihilation efficiency in the largest dendrimer with 64 porphyrins can be explained by the presence of a the two-step delayed annihilation process, involving energy hopping from excited to nonexcited chromophores prior to annihilation. In the smallest dendrimer with only four chromophores, delayed annihilation is not present, since the direct annihilation process is more efficient than the two-step delayed annihilation process. As the dendrimer size increases and the chances of originally exciting two neighboring chromophores decreases, the delayed annihilation process becomes more visible. The additional carbon, added to the connecting chain, results in more favorable chromophore distances and orientations for energy hopping. Hence, the improved energy transfer properties makes the Zn(II)-porphyrin-appended dendrimers with the additional carbon promising candidates as light-harvesting antennas for artificial photosynthesis.
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Affiliation(s)
- Jane Larsen
- Department of Chemical Physics, Lund University, Box 124, SE-221 00 Lund, Sweden
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41
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Yan X, Goodson T, Imaoka T, Yamamoto K. Up-converted emission in a series of phenylazomethine dendrimers with a porphyrin core. J Phys Chem B 2007; 109:9321-9. [PMID: 16852116 DOI: 10.1021/jp044105q] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nonlinear optical and time-resolved properties of a series of phenylazomethine-porphyrin dendrimers are reported. The linear optical properties were also investigated, and the efficiency of the energy transfer process was obtained. Measurements were also carried out with the basic building-block molecules. The process of frequency up-converted emission was observed in these porphyrin dendrimers. The mechanism for this effect is investigated and related to the process of "hot-band" absorption in the phenylazomethine-porphyrin system. Time-resolved measurements also suggested efficient intramolecular vibrational energy redistribution in these systems. These properties suggest that the porphyrin dendrimers may also have applications in light harvesting of low-frequency photons, as well as in sensors.
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Affiliation(s)
- Xingzhong Yan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48201, USA
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Yan Y, Li B, Liu K, Dong Z, Wang X, Qian S. Enhanced Two-Photon Absorption and Ultrafast Dynamics of a New Multibranched Chromophore with a Dibenzothiophene Core. J Phys Chem A 2007; 111:4188-94. [PMID: 17474724 DOI: 10.1021/jp067783g] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of novel compounds with dibenzothiophene core branched structures have been synthesized, and their two-photon absorption (TPA) properties were investigated. Two-photon fluorescence (TPF) and z-scan techniques were carried out, and a significant enhancement in the TPA cross section was observed for ST-G2, which possesses the largest generation number among the studied samples. By using different solvents, the largest nonlinear optical (NLO) response was observed in the most polar solvent. Ultrafast pump-probe experiments were performed to probe the excited state dynamics in the branched molecules, and the obtained results further confirmed the TPA enhancement mechanism. Time-resolved fluorescence (TRFL) and TRFL anisotropy measurements reveal that there is an ultrafast charge localization to the intramolecular charge transfer (ICT) state followed by relaxation with a lifetime longer than 1 ns.
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Affiliation(s)
- Yongli Yan
- Physics Department, Fudan University, Shanghai 200433, People's Republic of China, Surface Physics Lab (National Key Lab), Fudan University, Shanghai 200433, People's Republic of China
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Ramakrishna G, Goodson T. Excited-State Deactivation of Branched Two-Photon Absorbing Chromophores: A Femtosecond Transient Absorption Investigation. J Phys Chem A 2007; 111:993-1000. [PMID: 17249643 DOI: 10.1021/jp064004n] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Branched macromolecular structures are now an important area of research for enhanced two-photon absorption (TPA) cross sections. The mechanism of this enhancement has been suggested as a complex interplay between intramolecular interactions and the extent of charge-transfer character in the branches. In order to probe these processes more clearly, excited-state dynamics of multibranched chromophores by means of femtosecond transient absorption spectroscopy are reported. Investigations have been carried out on the PRL dye series (PRL-101, PRL-501, PRL-701), which have shown cooperative enhancement of the TPA cross section. Upon photoexcitation, transient absorption measurements have shown the presence of a localized charge-transfer (intramolecular charge transfer, ICT) state independent of branching. The results point to ultrafast localization of charge in this particular system of chromophores. Pump-probe measurements in highly polar solvents have shown the presence of a nonemissive charge-transfer state which is a solvent stabilized and conformationally relaxed state. The population of this nonemissive state increases from monomer to trimer, and thus, it has been used as indicator of the polar nature of the Franck-Condon state. These results have shown an increase of charge-transfer character of the excited state with an increase in branching, and this explains the relative increase in the two-photon cross section of the PRL series.
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Affiliation(s)
- Guda Ramakrishna
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Fakis M, Anestopoulos D, Giannetas V, Persephonis P. Influence of Aggregates and Solvent Aromaticity on the Emission of Conjugated Polymers. J Phys Chem B 2006; 110:24897-902. [PMID: 17149910 DOI: 10.1021/jp0619033] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The influence of aggregates and solvent aromaticity on the photophysics and fluorescence dynamics of two conjugated polymers is studied. The two polymers are derivatives of poly(p-phenylene vinylene) (PPV) containing different kinked moieties along the main chain. The polymers contain 2,6-diphenylpyridine and m-terphenyl kinked moieties and they are abbreviated as PN and PC, respectively. The insertion of kinked segments along the main chain shifts the emission spectrum from the yellow-orange spectral region, common to PPV derivatives, to the blue-green spectral region. The results show that in dilute solutions the polymers decay monoexponentially, while in concentrated ones the fluorescence decays biexponentially, indicating fluorescence quenching. This is attributed to an energy transfer process from polymer chains to aggregates that occurs within a few tens of picoseconds. By comparing the photophysics and fluorescence dynamics of polymer PN in a nonaromatic and an aromatic solvent, we conclude that the polymer conformation adopted in the aromatic solvent leads to a higher fluorescence quantum yield and a longer fluorescence lifetime. Furthermore, the fluorescence quenching of PN because of aggregates is faster and more efficient in the aromatic than in the nonaromatic solvent. These results can be explained through a more extended chain conformation of PN in the aromatic solvent.
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Affiliation(s)
- Mihalis Fakis
- Department of Physics, University of Patras, Patras 26504, Greece.
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Ahn TS, Nantalaksakul A, Dasari RR, Al-Kaysi RO, Müller AM, Thayumanavan S, Bardeen CJ. Energy and Charge Transfer Dynamics in Fully Decorated Benzyl Ether Dendrimers and Their Disubstituted Analogues. J Phys Chem B 2006; 110:24331-9. [PMID: 17134184 DOI: 10.1021/jp0649706] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examine the photophysics of a series of molecules consisting of a benzthiadiazole core surrounded by a network of benzyl ether arms terminated by aminopyrene chromophores, which function as both energy and electron donors. Three classes of molecules are studied: dendrimers whose peripheries are fully decorated with aminopyrene donors (F), disubstituted dendrimers whose peripheries contain only two donors (D), and linear analogues in which a pair of benzyl ether arms link two donors to the central core (L). The electronic energy transfer (EET) and charge transfer (CT) rates are determined by fluorescence lifetime measurements on the energy donors and electron acceptors, respectively. In all three types of molecules, the EET time scales as the square root of the generation number G, consistent with the flexible nature of the benzyl ether framework. Transient anisotropy measurements confirm that donor-donor energy hopping does not play a major role in determining the EET times. The CT dynamics occur on the nanosecond time scale and lead to stretched exponential decays, probably due to conformational disorder. Measurements at 100 degrees C confirm that conformational fluctuations play a role in the CT dynamics. The average CT time increases with G in the L and D molecules but decreases for the F dendrimers. This divergent behavior as G increases is attributed to the competing effects of larger donor-acceptor distances (which lengthen the CT time) versus a larger number of donors (which shorten the average CT time). This work illustrates two important points about light-harvesting and charge-separation dendrimers. First, the use of a flexible dendrimer framework can lead to a more favorable scaling of the EET time (and thus the light-harvesting efficiency) with dendrimer size, relative to what would be expected for a fully extended dendrimer. Second, fully decorated dendrimers can compensate for the distance-dependent slowdown in CT rate as G increases by providing additional pathways for the CT reaction to occur.
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Affiliation(s)
- Tai-Sang Ahn
- Department of Chemistry, University of California, Riverside, California 92521, USA
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Zhang XB, Feng JK, Ren AM, Sun CC. Theoretical Study of Two-Photon Absorption Properties of a Series of Ferrocene-Based Chromophores. J Phys Chem A 2006; 110:12222-30. [PMID: 17078618 DOI: 10.1021/jp062350z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structures, one-photon absorption (OPA), and two-photon absorption (TPA) properties of a series of ferrocene-based chromophores with TCF-type acceptors (TCF = 2-dicyanomethylene-3-cyano-4-methyl-2,5-dihydrofuran) have been studied by using the ZINDO-SOS method. The results have revealed that OPA and TPA of ferrocenyl derivatives are affected by the strength of the acceptor, especially the pi-bridge conjugation length. The TPA cross section increases with increasing acceptor strength and pi-bridge conjugation length. The TCF-type acceptor with a phenyl group can lead to a larger TPA cross section. Quadrupole molecules have the largest TPA cross sections (2000-3000 GM), which are about 4 times that of the corresponding dipolar molecules, indicating larger interactions between the top and bottom branches. Finally, the origins of the two-photon excitations for ferrocenyl derivatives are analyzed. The calculations show that ferrocenyl derivatives with TCF-type acceptors (especially quadrupole molecules) are promising candidates for TPA materials.
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Affiliation(s)
- Xiang-Biao Zhang
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Changchun, 130023, China
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Ramakrishna G, Bhaskar A, Goodson T. Ultrafast Excited State Relaxation Dynamics of Branched Donor-π-Acceptor Chromophore: Evidence of a Charge-Delocalized State. J Phys Chem B 2006; 110:20872-8. [PMID: 17048901 DOI: 10.1021/jp063262h] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Excited-state dynamics and complete transient absorption features of the trimer tris-4,4',4' '-(4-nitrophenyleethynyl)triphenylamine and the monomer 4-N,N-(dimethylamino)-4'-nitrotolane have been obtained from femtosecond pump-probe spectroscopy. The measurements are carried out to understand the mechanism behind enhanced two-photon absorption cross-sections of branched systems over their linear counterparts. Absorption and emission transition dipole moments of monomer and trimer in toluene have suggested that the emitting state of trimer is different from the monomer and probably is arising from the charge-delocalized C(3) symmetry state. Ultrafast transient absorption measurements on these molecules have spectroscopically validated the presence of an initial electron delocalized state with the C(3) symmetry state in the trimer molecule. The results have shown that there is a slower rate of internal conversion from the C(3) symmetry state to intramolecular charge transfer of trimer suggesting a barrier between them. Also, presence of a charge-stabilized state and involvement of a nonemissive state in the excited-state deactivation has been observed for both monomer and trimer.
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Affiliation(s)
- Guda Ramakrishna
- Department of Chemistry, University of Michigan, Ann Arbor, 48109, USA
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Bhaskar A, Ramakrishna G, Lu Z, Twieg R, Hales JM, Hagan DJ, Van Stryland E, Goodson T. Investigation of Two-Photon Absorption Properties in Branched Alkene and Alkyne Chromophores. J Am Chem Soc 2006; 128:11840-9. [PMID: 16953624 DOI: 10.1021/ja060630m] [Citation(s) in RCA: 217] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Novel alkene and alkyne branched structures have been synthesized, and their two-photon absorption (2PA) properties are reported. This series of alkene and alkyne trimer systems tests the mechanistic approach for enhancing the 2PA process which is usually dictated by the pi-bridging, delocalization length, and corresponding charge transfer on the 2PA cross sections. The results suggest that alkene branched systems have higher 2PA cross sections. While steady-state absorption and emission measurements were not successful in predicting the observed trend of 2PA cross sections, time-resolved measurements have explained the trends observed. It was found that, upon photoexcitation, there is an ultrafast charge localization to an intramolecular charge-transfer (ICT) state, followed by the presence of a solvent and conformationally relaxed ICT state in these branched systems.
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Affiliation(s)
- Ajit Bhaskar
- Department of Chemistry and Macromolecular Science, University of Michigan, Ann Arbor, Michigan 48109, USA
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Zhang XB, Feng JK, Ren AM, Sun CC. A comparative study of two-photon properties of zinc(II)-porphyrin, meso–meso singly-linked zinc(II)-diporphyrin and zinc(II) meso,meso-coupled porphyrin dimer via hydrogen bonding interactions. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.theochem.2006.05.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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50
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Fakis M, Anestopoulos D, Giannetas V, Persephonis P, Mikroyannidis J. Femtosecond Time Resolved Fluorescence Dynamics of a Cationic Water-Soluble Poly(fluorenevinylene-co-phenylenevinylene). J Phys Chem B 2006; 110:12926-31. [PMID: 16805593 DOI: 10.1021/jp056385v] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A recently synthesized cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene) was studied by means of steady state and femtosecond time resolved upconversion spectroscopy in aqueous and EtOH solutions. Steady state spectroscopic measurements showed that the polymer emits at the blue-green spectral region and that aggregates are formed in concentrated polymer solutions. The fluorescence dynamics of the polymer in concentrated solutions, studied at a range of emission wavelengths, exhibited a wavelength dependent and multiexponential decay, indicating the existence of various decay mechanisms. Specifically, a rapid decay at short emission wavelengths and a slow rise at long wavelengths were observed. Both features reveal an energy transfer process from isolated to aggregated chains. The contribution of the energy transfer process as well as of the isolated chains and the aggregates on the overall fluorescence decay of the polymer was determined. The dependence of the energy transfer rate and efficiency on polymer concentration was also examined.
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Affiliation(s)
- Mihalis Fakis
- Department of Physics, University of Patras, Patras 26500, Greece.
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