› › Photoinduced Intramolecular Electron Transfer In Donor Acceptor Molecules

Photoinduced Intramolecular Charge Transfer in Donor-Acceptor Biaryls and Resulting Applicational Aspects Regarding Fluorescent Probes and Solar Energy Conversion

Author : Michael Maus

Publisher : Universal-Publishers

Page : 223 pages

File Size : 41,5 MB

Release : 1998

Category : Technology & Engineering

ISBN : 1581120303

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Book Description

This study is focused on the effects of photoinduced intramolecular charge transfer (CT) in three differently twisted donor-acceptor (D-A) biphenyls. Taking into account a further pair of differently twisted D-A biaryls new universal insights into the photoinduced electronic and conformation dynamics of D-A biaryls are obtained. Furthermore, possible applications in fields of solar energy conversion and fluorescence sensing of microenvironments are demonstrated. Experimental means of stationary and time-resolved (ps to s) luminescence, transient absorption (sub-ps), polarization spectroscopy, high pressure and low temperature techniques are employed in conjunction with quantum chemical calculations. Twist angle and solvent dependent electron transfer (ET) interactions between the D and A aryl moieties are responsible for the low lying and solvatochromic intramolecular CT electron band which gains unusually high intensity through strong electronic coupling of the pure 1ET with the ground (S0) and 1La state. As regards the class of biaryl compounds, for the first time, an excited state electron transfer from the D to the A could be monitored by dual spectrally separated stimulated fluorescence bands with precursor-successor relationship on a sub-ps timescale for the D-A biphenyls. It is concluded that, in additon to the electronic interaction of 1ET with S0 and 1La, the electronic interaction with a close lying 1Lb state plays a fundamental role in the ET dynamics and the 1CT-S0 transition probability in D-A biaryls. The initial photoinduced conformational relaxation occurs towards planarity in all biaryls investigated. However, various results evidence that the highly twisted D-A biphenyl additionally performs a slow "excited state intramolecular back twist rotation" leading to a solvent polarity dependent conformational equilibrium between a more planar (CT) and a more twisted (CTR) conformer in S1(1CT). Using global analysis of the biexponential fluorescence decays as a function of temperature and pressure in medium polar solvents, the kinetics, thermodynamics, viscosity control and decomposed emission spectra associated with this adiabatic photoreaction are determined. The twist angle dependent ability of the D-A biphenyls to serve as fluorescent probes of micropolarity, changes of microviscosity or matrix order, protic solvents and pH is investigated. In particular, fluorescence sensing of pH seems to be promising.



Intramolecular Charge Transfer

Author : Ramprasad Misra

Publisher : John Wiley & Sons

Page : 257 pages

File Size : 43,31 MB

Release : 2018-02-27

Category : Science

ISBN : 3527801944

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Book Description

Bridging the gap between the multitude of advanced research articles and the knowledge newcomers to the field are looking for, this is a timely and comprehensive monograph covering the interdisciplinary topic of intramolecular charge transfer (ICT). The book not only covers the fundamentals and physico-chemical background of the ICT process, but also places a special emphasis on the latest experimental and theoretical studies that have been undertaken to understand this process and discusses key technological applications. After outlining the discovery of ICT molecules, the authors go on to discuss several important substance classes. They present the latest techniques for studying the underlying processes and show the interplay between charge transfer and the surrounding medium. Examples taken from nonlinear optics, viscosity and polarity sensors, and organic electronics testify to the vast range of applications. The result is a unique information source for experimentalists as well as theoreticians, from postgraduate students to researchers.



Light Harvesting in Photosynthesis

Author : Roberta Croce

Publisher : CRC Press

Page : 778 pages

File Size : 47,48 MB

Release : 2018-01-12

Category : Science

ISBN : 1351242873

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Book Description

This landmark collective work introduces the physical, chemical, and biological principles underlying photosynthesis: light absorption, excitation energy transfer, and charge separation. It begins with an introduction to properties of various pigments, and the pigment proteins in plant, algae, and bacterial systems. It addresses the underlying physics of light harvesting and key spectroscopic methods, including data analysis. It discusses assembly of the natural system, its energy transfer properties, and regulatory mechanisms. It also addresses light-harvesting in artificial systems and the impact of photosynthesis on our environment. The chapter authors are amongst the field’s world recognized experts. Chapters are divided into five main parts, the first focused on pigments, their properties and biosynthesis, and the second section looking at photosynthetic proteins, including light harvesting in higher plants, algae, cyanobacteria, and green bacteria. The third part turns to energy transfer and electron transport, discussing modeling approaches, quantum aspects, photoinduced electron transfer, and redox potential modulation, followed by a section on experimental spectroscopy in light harvesting research. The concluding final section includes chapters on artificial photosynthesis, with topics such as use of cyanobacteria and algae for sustainable energy production. Robert Croce is Head of the Biophysics Group and full professor in biophysics of photosynthesis/energy at Vrije Universiteit, Amsterdam. Rienk van Grondelle is full professor at Vrije Universiteit, Amsterdam. Herbert van Amerongen is full professor of biophysics in the Department of Agrotechnology and Food Sciences at Wageningen University, where he is also director of the MicroSpectroscopy Research Facility. Ivo van Stokkum is associate professor in the Department of Physics and Astronomy, Faculty of Sciences, at Vrije Universiteit, Amsterdam.



Halogen Bonding in Solution

Author : Stefan Huber

Publisher : John Wiley & Sons

Page : 418 pages

File Size : 13,77 MB

Release : 2021-04-19

Category : Technology & Engineering

ISBN : 3527347313

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Book Description

Long-awaited on the importance of halogen bonding in solution, demonstrating the specific advantages in various fields - from synthesis and catalysis to biochemistry and electrochemistry! Halogen bonding (XB) describes the interaction between an electron donor and the electrophilic region of a halogen atom. Its applicability for molecular recognition processes long remained unappreciated and has mostly been studied in solid state until recently. As most physiological processes and chemical reactions take place in solution, investigations in solutions are of highest relevance for its use in organic synthesis and catalysis, pharmaceutical chemistry and drug design, electrochemistry, as well as material synthesis. Halogen Bonding in Solution gives a concise overview of halogen bond interactions in solution. It discusses the history and electronic origin of halogen bonding and summarizes all relevant examples of its application in organocatalysis. It describes the use of molecular iodine in catalysis and industrial applications, as well as recent developments in anion transport and binding. Hot topic: Halogen bonding is an important interaction between molecules or within a molecule. The field has developed considerably in recent years, with numerous different approaches and applications having been published. Unique: There are several books on halogen bonding in solid state available, but this will be the first one focused on halogen bonding in solution. Multi-disciplinary: Summarizes the history and nature of halogen bonding in solution as well as applications in catalysis, anion recognition, biochemistry, and electrochemistry. Aimed at facilitating exciting future developments in the field, Halogen Bonding in Solution is a valuable source of information for researchers and professionals working in the field of supramolecular chemistry, catalysis, biochemistry, drug design, and electrochemistry.



Dynamics and Mechanisms of Photoinduced Electron Transfer and Related Phenomena

Author : N. Mataga

Publisher : Elsevier

Page : 587 pages

File Size : 21,76 MB

Release : 2012-12-02

Category : Science

ISBN : 0444598847

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Book Description

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.



Corundum

Author : Richard W. Hughes

Publisher : Tolley

Page : 348 pages

File Size : 47,16 MB

Release : 1990

Category : Corundum

ISBN :

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Book Description

Hughes, of the Asian Institute of Gemological Sciences, Bangkok, looks in detail at all aspects of rubies and sapphires, which, among the most sought after and precious of gems, account for over half of the world trade in colored gemstones. Includes 24 color plates and many bandw figures. Annotation copyrighted by Book News, Inc., Portland, OR



Handbook of Materials Modeling

Author : Sidney Yip

Publisher : Springer Science & Business Media

Page : 2903 pages

File Size : 25,60 MB

Release : 2007-11-17

Category : Science

ISBN : 1402032862

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Book Description

The first reference of its kind in the rapidly emerging field of computational approachs to materials research, this is a compendium of perspective-providing and topical articles written to inform students and non-specialists of the current status and capabilities of modelling and simulation. From the standpoint of methodology, the development follows a multiscale approach with emphasis on electronic-structure, atomistic, and mesoscale methods, as well as mathematical analysis and rate processes. Basic models are treated across traditional disciplines, not only in the discussion of methods but also in chapters on crystal defects, microstructure, fluids, polymers and soft matter. Written by authors who are actively participating in the current development, this collection of 150 articles has the breadth and depth to be a major contributor toward defining the field of computational materials. In addition, there are 40 commentaries by highly respected researchers, presenting various views that should interest the future generations of the community. Subject Editors: Martin Bazant, MIT; Bruce Boghosian, Tufts University; Richard Catlow, Royal Institution; Long-Qing Chen, Pennsylvania State University; William Curtin, Brown University; Tomas Diaz de la Rubia, Lawrence Livermore National Laboratory; Nicolas Hadjiconstantinou, MIT; Mark F. Horstemeyer, Mississippi State University; Efthimios Kaxiras, Harvard University; L. Mahadevan, Harvard University; Dimitrios Maroudas, University of Massachusetts; Nicola Marzari, MIT; Horia Metiu, University of California Santa Barbara; Gregory C. Rutledge, MIT; David J. Srolovitz, Princeton University; Bernhardt L. Trout, MIT; Dieter Wolf, Argonne National Laboratory.



Charge and Exciton Transport through Molecular Wires

Author : Laurens D. A. Siebbeles

Publisher : John Wiley & Sons

Page : 293 pages

File Size : 30,12 MB

Release : 2011-07-18

Category : Technology & Engineering

ISBN : 352763309X

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Book Description

As functional elements in opto-electronic devices approach the singlemolecule limit, conducting organic molecular wires are the appropriate interconnects that enable transport of charges and charge-like particles such as excitons within the device. Reproducible syntheses and a thorough understanding of the underlying principles are therefore indispensable for applications like even smaller transistors, molecular machines and light-harvesting materials. Bringing together experiment and theory to enable applications in real-life devices, this handbook and ready reference provides essential information on how to control and direct charge transport. Readers can therefore obtain a balanced view of charge and exciton transport, covering characterization techniques such as spectroscopy and current measurements together with quantitative models. Researchers are thus able to improve the performance of newly developed devices, while an additional overview of synthesis methods highlights ways of producing different organic wires. Written with the following market in mind: chemists, molecular physicists, materials scientists and electrical engineers.



Manganese Catalysis in Organic Synthesis

Author : Jean-Baptiste Sortais

Publisher : John Wiley & Sons

Page : 372 pages

File Size : 18,83 MB

Release : 2021-12-20

Category : Technology & Engineering

ISBN : 3527347305

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Book Description

Manganese Catalysis in Organic Synthesis A must-read reference for anyone interested in catalyst design and sustainable organic synthesis In Manganese Catalysis in Organic Synthesis, distinguished researcher Jean-Baptiste Sortais delivers an insightful and robust overview of the use of manganese in homogenous catalysis. The editor includes papers from authoritative academics describing the organometallic precursors used to develop manganese catalysts and covers critical applications in organic synthesis, including reduction to oxidation reactions, C-C, C-N, C-X bond formation reactions, cross-coupling reactions, C-H bond activation to dihydroxylation and epoxidation reactions. Manganese Catalysis in Organic Synthesis is a practical resource for every organic chemist in academia and industry with an interest in non-noble metal catalysis, organic synthesis, and sustainable chemistry. It is intuitively and clearly organized, covering the most important synthetic procedures using homogenous manganese catalysts. It is also the ideal companion to works like Cobalt Catalysis in Organic Synthesis, Nickel Catalysis in Organic Synthesis, and Iron Complexes in Catalysis. Readers will also enjoy: Thorough introductions to organometallic manganese compounds in organic synthesis and manganese-catalyzed hydrogenation and hydrogen transfer reactions A comprehensive exploration of manganese-catalyzed hydrogen borrowing reactions and dehydrogenative coupling reactions Practical discussions of manganese-catalyzed hydrosilylation and hydroboration reactions and manganese-catalyzed electro- and photocatalysis transformations In-depth examinations of manganese-catalyzed C-H oxygenation reactions and manganese-catalyzed organometallic C-H activation Insightful treatments of manganese-catalyzed cross-coupling processes and manganese(III) acetate mediated cyclizations Perfect for catalytic, organic, and pharmaceutical chemists, Manganese Catalysis in Organic Synthesis deserves a place in the libraries of researchers and professionals interested in catalyst design and sustainable organic synthesis.



Peptide Materials

Author : Carlos Aleman

Publisher : John Wiley & Sons

Page : 479 pages

File Size : 44,73 MB

Release : 2013-03-29

Category : Technology & Engineering

ISBN : 1118592417

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Book Description

Peptides are the building blocks of the natural world; with varied sequences and structures, they enrich materials producing more complex shapes, scaffolds and chemical properties with tailorable functionality. Essentially based on self-assembly and self-organization and mimicking the strategies that occur in Nature, peptide materials have been developed to accomplish certain functions such as the creation of specific secondary structures (a- or 310-helices, b-turns, b-sheets, coiled coils) or biocompatible surfaces with predetermined properties. They also play a key role in the generation of hybrid materials e.g. as peptide-inorganic biomineralized systems and peptide/polymer conjugates, producing smart materials for imaging, bioelectronics, biosensing and molecular recognition applications. Organized into four sections, the book covers the fundamentals of peptide materials, peptide nanostructures, peptide conjugates and hybrid nanomaterials, and applications with chapters including: Properties of peptide scaffolds in solution and on solid substrates Nanostructures, peptide assembly, and peptide nanostructure design Soft spherical structures obtained from amphiphilic peptides and peptide-polymer hybrids Functionalization of carbon nanotubes with peptides Adsorption of peptides on metal and oxide surfaces Peptide applications including tissue engineering, molecular switches, peptide drugs and drug delivery Peptide Materials: From Nanostructures to Applications gives a truly interdisciplinary review, and should appeal to graduate students and researchers in the fields of materials science, nanotechnology, biomedicine and engineering as well as researchers in biomaterials and bio-inspired smart materials.