Ultrafast Photoinduced Energy and Electron Transfer Studies in Closely Bound Molecular and Nanocarbon Donor-Acceptor Systems

Ultrafast Photoinduced Energy and Electron Transfer Studies in Closely Bound Molecular and Nanocarbon Donor-Acceptor Systems
Author: Habtom Berhane Gobeze
Publisher:
Total Pages: 306
Release: 2018
Genre: Charge exchange
ISBN:

As part of the study, photosynthetic system constructs based on BF2-chelated dipyrromethene (BODIPY), BF2-chelated azadipyrromethene (AzaBODIPY), porphyrin, phthalocyanine, oxasmaragdyrin, polythiophene, fullerene (C60), single-walled carbon nanotube and graphene are investigated. Antenna systems of BODIPY dyads and oligomers having BODIPY as an excitation energy donor connected to different acceptors including BODIPY, azaBODIPY, oxasmaragdyrin and aluminum porphyrin are studied. Different synthetic methodologies are used to afford donor-acceptor systems either directly linked with no spacer or with short spacers of varying length and orientation. The effect of donor orientation, donor optical gap as well as nature of donor-acceptor coupling on the donor-acceptor spectral overlap and hence the rate of excitation energy transfer is investigated. In all these systems, an ultrafast energy transfer followed by electron transfer is observed. In particular, in a directly connected BODIPY-azaBODIPY dyad an unusually ultrafast energy transfer (̃ 150−200 f̧ ' ) via F©œrster mechanism is observed. The observation of energy transfer via F©œrster instead of Dexter mechanism in such closely coupled donor-acceptor systems shows the balance between spatial and electronic coupling achieved in the donor-acceptor system. Moreover, in donor-acceptor systems involving semiconducting 1D and 2D materials, covalently functionalized single-walled carbon nanotubes via charge stabilizing (TPA)3ZnP and noncovalently hybridized exfoliated graphene via polythiophene chromophores are studied for their charge transportation functions. In both cases, not only an ultrafast charge transfer in the range of (̃ 2−5 p̧ ' ) is observed but also the charge-separated states were long lived implying the potential of these functionalized materials as efficient charge transporting substrates with organic chromophores for photovoltaic and optoelectronic applications where ultrafast intercomponent charge transfer is vital. In addition, as a final part of this dissertation, the mechanisms of electron injection and back electron transfer in heterogeneous systems involving supramolecularly anchored high potential chromophores on TiO2 film are studied by femtosecond transient absorption spectroscopy. In this study, not only are important insights gained on the utilization of supramolecular anchoring of chromophores such as porphyrins, phthalocyanines, and their perflorinated high potential analogues, chromophores currently showing promise as highly efficient sensitizers in dye sensitized solar cells, on TiO2 film but also on the effect of anchor length and sensitizer orientation on the rates of electron injection and back electron transfer at the sensitizer-TiO2 interface.

Electron Transfer

Electron Transfer
Author: Joshua Jortner
Publisher: Wiley-Interscience
Total Pages: 812
Release: 1999-02-08
Genre: Science
ISBN:

an integrated approach to electron transfer phenomena This two-part stand-alone volume in the prestigious Advances in Chemical Physics series provides the most comprehensive overview of electron transfer science today. It draws on cutting-edge research from diverse areas of chemistry, physics, and biology-covering the most recent developments in the field, and pointing to important future trends. This initial volume includes: * A historical perspective spanning five decades * A review of concepts, problems, and ideas in current research * Electron transfer in isolated molecules and in clusters * General theory, including useful algorithms * Spectra and electron transfer kinetics in bridged compounds The second volume covers solvent control, ultrafast electron transfer and coherence effects, molecular electronics, electron transfer and chemistry, and biomolecules. Electron transfer science has seen tremendous progress in recent years. Technological innovations, most notably the advent of femtosecond lasers, now permit the real-time investigation of intramolecular and intermolecular electron transfer processes on a time scale of nuclear motion. New scientific information abounds, illuminating the processes of energy acquisition, storage, and disposal in large molecules, clusters, condensed phase, and biophysical systems. Electron Transfer: From Isolated Molecules to Biomolecules is the first book devoted to the exciting work being done in nonradiative electron transfer dynamics today. This two-part edited volume emphasizes the interdisciplinary nature of the field, bringing together the contributions of pioneers in chemistry, physics, and biology. Both theoretical and experimental topics are featured. The authors describe modern approaches to the exploration of different systems, including supersonic beam techniques, femtosecond laser spectroscopy, chemical syntheses, and methods in genetic and chemical engineering. They examine applications in such areas as supersonic jets, solvents, electrodes, semi- conductors, respiratory and enzymatic protein systems, photosynthesis, and more. They also relate electron transfer and radiationless transitions theory to pertinent physical phenomena, and provide a conceptual framework for the different processes. Complete with over two hundred illustrations, Part One reviews developments in the field since its inception fifty years ago, and discusses electron transfer phenomena in both isolated molecules and in clusters. It outlines the general theory, exploring areas of the control of kinetics, structure-function relationships, fluctuations, coherence, and coupling to solvents with complex spectral density in different types of electron transfer processes. Timely, comprehensive, and authoritative, Electron Transfer: From Isolated Molecules to Biomolecules is an essential resource for physical chemists, molecular physicists, and researchers working in nonradiative dynamics today.

Ultrafast Photoinduced Electron Transfer Reactions in Supramolecular Arrays

Ultrafast Photoinduced Electron Transfer Reactions in Supramolecular Arrays
Author:
Publisher:
Total Pages: 5
Release: 1993
Genre:
ISBN:

Research in our laboratory focuses on developing supramolecular arrays that produce long-lived charge separation by limiting the electronic coupling between the separated charges, and on the role of solvation in determining the rates and energetics of photoinitiated electron transfer reactions. Arrays have been developed that closely mimic the electronic coupling that was observed only for long-lived radical pairs produced in photosynthetic glassy solids. A series of 36 fixed-distance donor-acceptor molecules using porphyrin donors, triptycene spacers, and 9 different acceptors has been prepared; these are used to probe the dependence of photoinduced charge separation rates on free energy of reaction as a function of solvent both in liquid and solid solution. Data were obtained on rates of charge separation in dioxane, MTHF, butyronitrile, toluene, chlorobenzene, and benzonitrile.

Electron Transfer

Electron Transfer
Author: Shunichi Fukuzumi
Publisher: John Wiley & Sons
Total Pages: 341
Release: 2020-01-29
Genre: Science
ISBN: 3527651799

Written by one of the top scientists in this field, this is a systematic overview of the fundamental concepts and powerful applications. The author presents the central theories and mechanisms in electron transfer, followed by several systems in nature where this is important, while also covering modern green applications. An invaluable resource for graduate students and researchers working in this field in academia and industry.

Dynamics and Mechanisms of Photoinduced Electron Transfer and Related Phenomena

Dynamics and Mechanisms of Photoinduced Electron Transfer and Related Phenomena
Author: N. Mataga
Publisher: Elsevier
Total Pages: 587
Release: 2012-12-02
Genre: Science
ISBN: 0444598847

This book contains papers which examine fundamental aspects of photoinduced electron transfer reactions, an area in which a number of breakthroughs have recently occurred. The book is divided into four parts. Parts I and II are mainly concerned with the fundamental aspects of the inter- and intra-molecular charge transfer, electron transfer and related phenomena such as solvent effects, solvation dynamics, energy gap dependences and radical pair dynamics. Part III is concerned with electron transfer and energy transfer phenomena in polymers, films, crystals, and other confined systems. In Part IV, the mechanisms of the energy and electron transfer in biological photosynthetic systems, proteins and reaction center systems are discussed.

Ultrafast Photoinduced Energy and Charge Transfer

Ultrafast Photoinduced Energy and Charge Transfer
Author: Royal Society of Chemistry, The
Publisher: Faraday Discussions
Total Pages: 590
Release: 2019-07-24
Genre:
ISBN: 9781788016735

Ultrafast energy and charge transfer events dictate the functionality of a broad range of molecular, aggregate and nanomaterial systems. Impressive recent advances in the commercialisation of ultrafast laser technology and on many theoretical fronts, plus the societal emphasis on solar energy, have led to a surge of research in this community, encompassing spectroscopists, biophysicists, computational and theoretical chemists, physicists and materials scientists. Ambitions have evolved beyond studies of simple molecular systems, and increasingly focus on the underlying molecular mechanisms prevailing in nanomaterial, native protein and hybrid systems. Many working in this area share a common aim, to address and answer one of the most pressing issues currently facing the scientific community: the photophysics underlying efficient light capture, energy transport and efficient charge carrier generation, water splitting, photo-protection and photo-damage, proton transfer and/or molecular re-organisation. This volume discusses the following themes: Energy and charge-transfer in natural photosynthesis Photovoltaics and bio-inspired light harvesting Photo-induced electron transfer Photo-protection/photo-damage in natural systems

Ultrafast Photoinduced Energy and Charge Transfer

Ultrafast Photoinduced Energy and Charge Transfer
Author:
Publisher:
Total Pages: 587
Release: 2019
Genre: Charge transfer
ISBN:

Ultrafast energy and charge transfer events dictate the functionality of a broad range of molecular, aggregate and nanomaterial systems. Impressive recent advances in the commercialisation of ultrafast laser technology and on many theoretical fronts, plus the societal emphasis on solar energy, have led to a surge of research in this community, encompassing spectroscopists, biophysicists, computational and theoretical chemists, physicists and materials scientists. Ambitions have evolved beyond studies of simple molecular systems, and increasingly focus on the underlying molecular mechanisms prevailing in nanomaterial, native protein and hybrid systems. Many working in this area share a common aim, to address and answer one of the most pressing issues currently facing the scientific community: the photophysics underlying efficient light capture, energy transport and efficient charge carrier generation, water splitting, photo-protection and photo-damage, proton transfer and/or molecular re-organisation. This volume discusses the following themes: Energy and charge-transfer in natural photosynthesis; Photovoltaics and bio-inspired light harvesting; Photo-induced electron transfer; Photo-protection/photo-damage in natural systems.

Factoring the Contribution of Through-space and Through-bond Interactions to Rates of Photoinduced Electron Transfer in Donor- Spacer-acceptor Molecules Using Ultrafast Transient Absorption Spectroscopy

Factoring the Contribution of Through-space and Through-bond Interactions to Rates of Photoinduced Electron Transfer in Donor- Spacer-acceptor Molecules Using Ultrafast Transient Absorption Spectroscopy
Author:
Publisher:
Total Pages: 3
Release: 1996
Genre:
ISBN:

Contributions from through-space and through-bond interactions to the electronic coupling matrix elements for photoinduced charge separation and recombination in linked donor-spacer-acceptor molecules were studied. The molecules consisted of a 4-piperidinyl-naphthalene-1,8-dicarboximide electron donor and a N-(n-octyl)pyromellitimide electron acceptor attached to the 1,5- and 1,8-positions of either anthracene or dibenzobicyclo(2.2.2)octatriene spacers.