Download or read book The Photochemical and Mechanochemical Ring Opening of Cyclobutene from First Principles written by Mitchell T. Ong and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A textbook example of a pericyclic reaction is the electrocyclic ring opening of cyclobutene. The stereochemical outcome of this reaction can typically be predicted using the Woodward-Hoffmann rules, which are based on conservation of orbital symmetry. According to these rules, the thermal ring opening reaction will proceed in conrotatory fashion, while the photochemical ring opening reaction will proceed in disrotatory fashion. Over the years, there have been very few exceptions to the Woodward-Hoffmann rules. However, two apparent exceptions to these rules occur when the ring opening of cyclobutene is initiated by exciting the molecule with light or by applying a mechanical force. In this work, we use first principles quantum mechanics and molecular dynamics to examine the photochemical and mechanochemical ring opening of cyclobutene. We use the ab initio multiple spawning (AIMS) method in order to examine the short time dynamics of cyclobutene. We have integrated the COLUMBUS software package into AIMS, which contains analytical gradients and nonadiabatic couplings for multi-reference configuration interaction (MRCI). This provides us with a more accurate potential energy surface in which to run our dynamics on. We find that the stereochemistry for ring opening is determined on the ground state. We have also identified two S1/S0 intersections that could be relevant to the photochemical ring opening reaction. One of these intersections contains a sizable C=C torsional angle, which could explain the mixture of conrotatory and disrotatory products seen in experiment. In addition, we model the mechanical response of cyclobutene within the context of a force-modified potential energy surface (FMPES). Using this model, we perform ab initio steered molecular dynamics (AISMD) to predict possible reaction outcomes when an external force is applied. Furthermore, we locate minimum energy pathways directly on the FMPES using the nudged elastic band (NEB) algorithm. Application of an external force can bias the reaction to produce a specific product by reshaping the potential energy surface and effectively blocking off access to other competing pathways. Barrier heights and stationary point geometries along the pathways can also change as a function of the force. Finally, we apply AISMD and NEB to other new mechanophores that are currently being studied including gem-difluorocyclopropane and dicyano-cyclobutane. Both of these methods can be used to screen new mechanophores, which will aid in designing new polymeric materials that respond favorably to mechanical stress.
Download or read book Theoretical and Computational Photochemistry written by García Iriepa Cristina and published by Elsevier. This book was released on 2023-04-21 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical and Computational Photochemistry: Fundamentals, Methods, Applications and Synergy with Experimental Approaches provides a comprehensive overview of photoactive systems and photochemical processes. After an introduction to photochemistry, the book discusses the key computational chemistry methods applied to the study of light-induced processes over the past decade, and further outlines recent research topics to which these methods have been applied. By discussing the synergy between experimental and computational data, the book highlights how theoretical studies could facilitate understanding experimental findings. This helpful guide is for both theoretical chemists and experimental photochemistry researchers interested in utilizing computational photochemistry methods for their own work. Reviews the fundamentals of photochemistry, helping those new to the field in understanding key concepts Provides detailed guidance and comparison of computational and theoretical methods, highlighting the suitability of each method for different case studies Outlines current applications to encourage discussion of the synergy between experimental and computational data, and inspiring further application of these methods to other photochemical processes
Download or read book Reviews in Computational Chemistry Volume 31 written by Abby L. Parrill and published by John Wiley & Sons. This book was released on 2018-10-25 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Reviews in Computational Chemistry series brings together leading authorities in the field to teach the newcomer and update the expert on topics centered on molecular modeling, such as computer-assisted molecular design (CAMD), quantum chemistry, molecular mechanics and dynamics, and quantitative structure-activity relationships (QSAR). This volume, like those prior to it, features chapters by experts in various fields of computational chemistry. Topics in Volume 31 include: Lattice-Boltzmann Modeling of Multicomponent Systems: An Introduction Modeling Mechanochemistry from First Principles Mapping Energy Transport Networks in Proteins The Role of Computations in Catalysis The Construction of Ab Initio Based Potential Energy Surfaces Uncertainty Quantification for Molecular Dynamics
Download or read book Photochemical Synthesis and Electrocyclic Ring Opening of Cyclobutene fused Bicyclic Systems written by Michael J. Robertson-Ralph and published by . This book was released on 2016 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Quantum Dynamics written by Fabien Gatti and published by Springer Science & Business Media. This book was released on 2014-04-09 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on current applications of molecular quantum dynamics. Examples from all main subjects in the field, presented by the internationally renowned experts, illustrate the importance of the domain. Recent success in helping to understand experimental observations in fields like heterogeneous catalysis, photochemistry, reactive scattering, optical spectroscopy, or femto- and attosecond chemistry and spectroscopy underline that nuclear quantum mechanical effects affect many areas of chemical and physical research. In contrast to standard quantum chemistry calculations, where the nuclei are treated classically, molecular quantum dynamics can cover quantum mechanical effects in their motion. Many examples, ranging from fundamental to applied problems, are known today that are impacted by nuclear quantum mechanical effects, including phenomena like tunneling, zero point energy effects, or non-adiabatic transitions. Being important to correctly understand many observations in chemical, organic and biological systems, or for the understanding of molecular spectroscopy, the range of applications covered in this book comprises broad areas of science: from astrophysics and the physics and chemistry of the atmosphere, over elementary processes in chemistry, to biological processes (such as the first steps of photosynthesis or vision). Nevertheless, many researchers refrain from entering this domain. The book "Molecular Quantum Dynamics" offers them an accessible introduction. Although the calculation of large systems still presents a challenge - despite the considerable power of modern computers - new strategies have been developed to extend the studies to systems of increasing size. Such strategies are presented after a brief overview of the historical background. Strong emphasis is put on an educational presentation of the fundamental concepts, so that the reader can inform himself about the most important concepts, like eigenstates, wave packets, quantum mechanical resonances, entanglement, etc. The chosen examples highlight that high-level experiments and theory need to work closely together. This book thus is a must-read both for researchers working experimentally or theoretically in the concerned fields, and generally for anyone interested in the exciting world of molecular quantum dynamics.
Download or read book Reviews in Computational Chemistry Volume 31 written by Abby L. Parrill and published by John Wiley & Sons. This book was released on 2018-11-06 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Reviews in Computational Chemistry series brings together leading authorities in the field to teach the newcomer and update the expert on topics centered on molecular modeling, such as computer-assisted molecular design (CAMD), quantum chemistry, molecular mechanics and dynamics, and quantitative structure-activity relationships (QSAR). This volume, like those prior to it, features chapters by experts in various fields of computational chemistry. Topics in Volume 31 include: Lattice-Boltzmann Modeling of Multicomponent Systems: An Introduction Modeling Mechanochemistry from First Principles Mapping Energy Transport Networks in Proteins The Role of Computations in Catalysis The Construction of Ab Initio Based Potential Energy Surfaces Uncertainty Quantification for Molecular Dynamics
Download or read book Polymer Mechanochemistry written by Roman Boulatov and published by Springer. This book was released on 2015-10-17 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.
Download or read book The Conservation of Orbital Symmetry written by R. B. Woodward and published by Elsevier. This book was released on 2013-10-22 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain—or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book opens with a review of the elementary aspects of the molecular orbital theory of bonding. This is followed by separate chapters on correlation diagrams, the conservation of orbital symmetry, theory of electrocyclic reactions, theory of cycloadditions and cycloreversions, and theory of sigmatropic reactions. Subsequent chapters deal with group transfers and eliminations; secondary conformational effects in concerted cycloaddition reactions; and generalized selection rules for pericyclic reactions.
Download or read book Small Ring Compounds in Organic Synthesis III written by Armin de Meijere and published by Springer. This book was released on 2013-10-03 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diradicaloids written by Jishan Wu and published by CRC Press. This book was released on 2022-04-01 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: π-Conjugated molecules with an even number of π-electrons usually have a closed-shell ground state. However, recent studies have demonstrated that a certain type of molecules could show open-shell singlet ground state and display diradical-like (diradicaloid) behavior. Their electronic structure can be understood in terms of the “diradical character” and “aromaticity” concepts. They display very different electronic properties from traditional closed-shell π-conjugated molecules and could be used as next-generation molecular materials. This book provides a comprehensive review on the chemistry, physics, and material applications of open-shell singlet diradicaloids. Particularly, it elaborates the fundamental structure–diradical character–electronic property relationships both theoretically and experimentally. The book has been written by leading scientists in the field from Japan, Germany, Spain, Italy, China, and Singapore.
Download or read book Fundamentals of Microfabrication and Nanotechnology Three Volume Set written by Marc J. Madou and published by CRC Press. This book was released on 2018-12-14 with total page 1992 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in its third edition, Fundamentals of Microfabrication and Nanotechnology continues to provide the most complete MEMS coverage available. Thoroughly revised and updated the new edition of this perennial bestseller has been expanded to three volumes, reflecting the substantial growth of this field. It includes a wealth of theoretical and practical information on nanotechnology and NEMS and offers background and comprehensive information on materials, processes, and manufacturing options. The first volume offers a rigorous theoretical treatment of micro- and nanosciences, and includes sections on solid-state physics, quantum mechanics, crystallography, and fluidics. The second volume presents a very large set of manufacturing techniques for micro- and nanofabrication and covers different forms of lithography, material removal processes, and additive technologies. The third volume focuses on manufacturing techniques and applications of Bio-MEMS and Bio-NEMS. Illustrated in color throughout, this seminal work is a cogent instructional text, providing classroom and self-learners with worked-out examples and end-of-chapter problems. The author characterizes and defines major research areas and illustrates them with examples pulled from the most recent literature and from his own work.
Download or read book Handbook of Gas Sensor Materials written by Ghenadii Korotcenkov and published by Springer Science & Business Media. This book was released on 2013-09-18 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two volumes of Handbook of Gas Sensor Materials provide a detailed and comprehensive account of materials for gas sensors, including the properties and relative advantages of various materials. Since these sensors can be applied for the automation of myriad industrial processes, as well as for everyday monitoring of such activities as public safety, engine performance, medical therapeutics, and in many other situations, this handbook is of great value. Gas sensor designers will find a treasure trove of material in these two books.
Download or read book Handbook of Gas Sensor Materials written by Ghenadii Korotcenkov and published by Springer Science & Business Media. This book was released on 2013-11-08 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two volumes of Handbook of Gas Sensor Materials provide a detailed and comprehensive account of materials for gas sensors, including the properties and relative advantages of various materials. Since these sensors can be applied for the automation of myriad industrial processes, as well as for everyday monitoring of such activities as public safety, engine performance, medical therapeutics, and in many other situations, this handbook is of great value. Gas sensor designers will find a treasure trove of material in these two books.
Download or read book The Chemistry of Cyclobutanes written by Zvi Rappoport and published by . This book was released on 2005 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Sonochemistry written by T. J. Mason and published by Wiley-VCH. This book was released on 2002-05-06 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Power ultrasound has been used for many years in two specific industrial areas: cleaning and plastic welding. Over the last ten years an increasing interest has been shown in its potential for use over a much wider range of chemistry and processing which has been grouped together under the general title of sonochemistry. Most of these uses depend on the generation of acoustic cavitation in liquid media but this text, while underlining the importance of the physics and mathematics of cavitation, mainly concentrates on applications of the technology. After an introduction to the topic and some historical background to the uses of power ultrasound the general principles of acoustic cavitation are explored including some background physics, bubble dynamics and factors which influence cavitation. The remainder of the book incorporates a series of applications of sonochemistry which illustrate the types of physical and chemical effects of ultrasonically induced cavitation which will interest chemists and engineers alike. Amongst the major topics included are chemical synthesis, environmental protection and remediation of water, sewage and soils, polymer synthesis and processing, electrochemistry including both analytical and synthetic aspects and plating. The final chapter reviews the range of ultrasonic equipment available in the laboratory and the progress made towards the scale-up of sonochemistry. The level is introductory to semi-advanced and no topic has been taken to a particularly specialist level since it is intended that this should be of general interest to readers with a scientific background.
Download or read book Bioisosteres in Medicinal Chemistry written by Nathan Brown and published by John Wiley & Sons. This book was released on 2012-06-18 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written with the practicing medicinal chemist in mind, this is the first modern handbook to systematically address the topic of bioisosterism. As such, it provides a ready reference on the principles and methods of bioisosteric replacement as a key tool in preclinical drug development. The first part provides an overview of bioisosterism, classical bioisosteres and typical molecular interactions that need to be considered, while the second part describes a number of molecular databases as sources of bioisosteric identification and rationalization. The third part covers the four key methodologies for bioisostere identification and replacement: physicochemical properties, topology, shape, and overlays of protein-ligand crystal structures. In the final part, several real-world examples of bioisosterism in drug discovery projects are discussed. With its detailed descriptions of databases, methods and real-life case studies, this is tailor-made for busy industrial researchers with little time for reading, while remaining easily accessible to novice drug developers due to its systematic structure and introductory section.
Download or read book The Diels Alder Reaction written by Francesco Fringuelli and published by John Wiley & Sons. This book was released on 2002-01-21 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: 70 Jahre Forschung an der Diels-Alder-Reaktion: Dieses Buch fasst die wichtigsten und beeindruckendsten Ergebnisse in einzigartiger Weise zusammen! Zunächst werden die Grundprinzipien der Reaktion klar und verständlich anhand übersichtlicher Graphiken erläutert. Spezielle Vorschriften und gegebenenfalls ihre industrielle Umsetzung werden anschließend erklärt. Einen Schwerpunkt bilden auch physikalische und katalytische Verfahren zur Steigerung der Selektivität der Reaktion. Cycloadditionen in konventionellen und unkonventionellen Medien werden vorgestellt. Mit über 1.000 Literaturverweisen!
