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Electrocatalysis in Fuel Cells

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ISBN: 9783038422341 9783038422198 Year: Pages: XXX, 658 DOI: 10.3390/books978-3-03842-219-8 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2016-07-12 11:10:02
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First-Principles Approaches to Metals, Alloys, and Metallic Compounds

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ISBN: 9783038973584 9783038973591 Year: Pages: 180 DOI: 10.3390/books978-3-03897-359-1 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Mining and Metallurgy --- Chemistry (General)
Added to DOAB on : 2018-11-26 11:24:24
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Current fundamental electronic-structure theory allows for the accurate prediction and characterization of elemental metals adopting any allotropic structure, intermetallic compounds, and other metal-rich phases. From an engineering perspective, there is a need for structural materials that are suitable for mechanical and civil engineering as well as energy production and conversion. While different microstructural features influence the macroscopic behaviour, quantum-mechanical simulation may enormously accelerate and guide the entire development process since atomistic modelling allows for the generation of structural models and the calculation of enthalpies and other free energies as a function of pressure and temperature. Among other things, this volume covers high-manganese steels, some of which have come to light within Collaborative Research Centre 761 (“Steel ab initio”). In particular, it deals with short-range ordering from experiment and theory, also highlighting carbide-like precipitates, and it bridges the gap between atomistic and continuum levels, in particular for hydrogen embrittlement. Molecular dynamics simulates crack propagation, and first-principles theory helps in growing better intermetallic thin films and predicts structural and elastic properties. Eventually, multiscale modelling of hydrogen transport is provided, and the chemical reasons for H-trapping κ-carbides are highlighted. First-principles theory has acquired a powerful role in the fundamental and applied research of metals, alloys, and metallic compounds.

Quantum Mechanical/Molecular Mechanical Approaches for the Investigation of Chemical Systems - Recent Developments and Advanced Applications

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456260 Year: Pages: 188 DOI: 10.3389/978-2-88945-626-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-01-23 14:53:43
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The QM/MM method, short for quantum mechanical/molecular mechanical, is a highly versatile approach for the study of chemical phenomena, combining the accuracy of quantum chemistry to describe the region of interest with the efficiency of molecular mechanical potentials to represent the remaining part of the system. Originally conceived in the 1970s by the influential work of the the Nobel laureates Martin Karplus, Michael Levitt and Arieh Warshel, QM/MM techniques have evolved into one of the most accurate and general approaches to investigate the properties of chemical systems via computational methods. Whereas the first applications have been focused on studies of organic and biomolecular systems, a large variety of QM/MM implementations have been developed over the last decades, extending the range of applicability to address research questions relevant for both solution and solid-state chemistry as well. Despite approaching their 50th anniversary in 2022, the formulation of improved QM/MM methods is still an active field of research, with the aim to (i) extend the applicability to address an even broader range of research questions in chemistry and related disciplines, and (ii) further push the accuracy achieved in the QM/MM description beyond that of established formulations. While being a highly successful approach on its own, the combination of the QM/MM strategy with other established theoretical techniques greatly extends the capabilities of the computational approaches. For instance the integration of a suitable QM/MM technique into the highly successful Monte-Carlo and molecular dynamics simulation protocols enables the description of the chemical systems on the basis of an ensemble that is in part constructed on a quantum-mechanical basis. This eBook presents the contributions of a recent Research Topic published in Frontiers in Chemistry, that highlight novel approaches as well as advanced applications of QM/MM method to a broad variety of targets. In total 2 review articles and 10 original research contributions from 48 authors are presented, covering 12 different countries on four continents. The range of research questions addressed by the individual contributions provide a lucid overview on the versatility of the QM/MM method, and demonstrate the general applicability and accuracy that can be achieved for different problems in chemical sciences. Together with the development of improved algorithms to enhance the capabilities of quantum chemical methods and the continuous advancement in the capacities of computational resources, it can be expected that the impact of QM/MM methods in chemical sciences will be further increased already in the near future.

Zweikomponentige Methoden im Rahmen der zeitabhängigen Dichtefunktionaltheorie - Theorie, Implementierung und Anwendung

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ISBN: 9783731504283 Year: Pages: 215 p. DOI: 10.5445/KSP/1000048734 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Chemistry (General)
Added to DOAB on : 2019-07-30 20:01:59
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This book reports on the derivation, implementation and application of two-component methods in the framework of time-dependent density functional theory. These methods allow the calculation of electronic transitions as well as the calculation of the correlation contribution to the electronic ground-state energy (RPA) and to the orbital energies (GW) including spin-orbit coupling. The focus of the applications is put on organic light-emitting diodes and clusters of heavy metals.

Amide Bond Activation

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ISBN: 9783039212033 / 9783039212040 Year: Pages: 466 DOI: 10.3390/books978-3-03921-204-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-08-28 11:21:27
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The amide bond represents a privileged motif in chemistry. The recent years have witnessed an explosion of interest in the development of new chemical transformations of amides. These developments cover an impressive range of catalytic N–C bond activation in electrophilic, Lewis acid, radical, and nucleophilic reaction pathways, among other transformations. Equally relevant are structural and theoretical studies that provide the basis for chemoselective manipulation of amidic resonance. This monograph on amide bonds offers a broad survey of recent advances in activation of amides and addresses various approaches in the field.

Keywords

fumardiamide --- primaquine --- succindiamide --- Michael acceptor --- biofilm eradication --- antibacterial screening --- antiviral activity --- cytostatic activity --- N,N-dimethylformamide --- DMF --- N,N-dimethylacetamide --- DMAc --- amination --- amidation --- thioamidation --- formylation --- carbonylation --- cyanation --- insertion --- cyclization --- amide --- arynes --- insertion --- activation --- heterocycles --- organic synthesis --- multi-component coupling reaction --- aryl thioamides --- thiourea --- C-H/C-N activation --- C-S formation --- transition-metal-free --- rotational barrier energy --- amide bond --- nuclear magnetic resonance --- kinetic --- density functional theory --- non planar amide --- base-catalyed hydrolysis --- water solvation --- entropy --- transamidation --- amide --- amine --- catalyst --- catalysis --- acylative cross-coupling --- trialkylborane --- amide activation --- palladium --- N-heterocyclic carbene --- ruthenium (Ru) --- N-heterocyclic carbenes (NHCs) --- homogeneous catalysis --- in situ --- amide bonds --- synthesis --- density functional theory --- cis/trans isomerization --- secondary amides --- dipeptides --- steric effects --- tert-butyl --- additivity principle --- amino acid transporters --- amide bond --- gemcitabine prodrug --- metabolic stability --- pancreatic cancer cells --- pharmacokinetics --- peptide bond cleavage --- amide bond resonance --- twisted amides --- enzymes --- metal complexes --- catalysts --- amide C–N bond activation --- nickel catalysis --- amidation --- DFT study --- reaction thermodynamics --- amide resonance --- anomeric effect --- HERON reaction --- pyramidal amides --- physical organic chemistry --- reaction mechanism --- amide --- activation --- amidicity --- carbonylicity --- transamidation --- acyl transfer --- excited state --- Suzuki-Miyaura --- cross-coupling --- aryl esters --- C–O activation --- Pd-catalysis --- amides --- carbanions --- C–H acidity --- nitro-aci tautomerism --- molecular dynamics --- density-functional theory --- alkynes --- C–H bond cleavage --- C–N bond cleavage --- cyclopentadienyl complexes --- N-(1-naphthyl)acetamide --- rhodium --- [2+2+2] annulation --- amide bond --- sulfonamide bond --- alkynes --- addition reaction --- aminoacylation --- aminosulfonylation --- pre-catalysts --- palladium catalysis --- amide bond activation --- ester bond activation --- cross-coupling --- amide bond --- bridged lactams --- twisted amides --- amides --- Winkler-Dunitz parameters --- N–C activation --- hypersensitivity --- nitrogen heterocycles --- distortion --- bridged sultams --- amides --- C-N ? bond cleavage --- sodium --- crown ether --- amide hydrolysis --- model compound --- intramolecular catalysis --- twisted amide --- protease --- intein --- C-H functionalization --- directing groups --- amides --- transition metals --- catalysis

Novel Photoactive Materials

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ISBN: 9783038976509 Year: Pages: 166 DOI: 10.3390/books978-3-03897-651-6 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Science (General)
Added to DOAB on : 2019-03-05 14:29:32
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Photoactivity represents the ability of a material, generally speaking a semiconductor, to become active when interacting with light. It can be declined in many ways, and several functionalities arising from this behavior of materials can be exploited, all leading to positive repercussions on our environment. There are several classes of effects of photoactivity, all of which have been deeply investigated in the last few decades, allowing to develop more and more efficient materials and devices. All of them share a common point, that is, the interaction of a material with light, although many different materials are taken into account depending on the effect desired—from elemental semiconductors like silicon, to more complex compounds like CdTe or GaAs, to metal oxides like TiO2 and ZnO. Given the broadness of the field, a huge number of works fall within this topic, and new areas of discovery are constantly explored. The special issue “Novel Photoactive Materials” has been proposed as a means to present recent developments in the field, and for this reason the articles included touch different aspects of photoactivity, from photocatalysis to photovoltaics to light emitting materials.

Coordination Chemistry of Silicon

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ISBN: 9783038976387 Year: Pages: 225 DOI: 10.3390/books978-3-03897-639-4 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General) --- Inorganic Chemistry
Added to DOAB on : 2019-03-08 11:42:05
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The chemistry of silicon has always been a field of major concern due to its proximity to carbon on the periodic table. From the molecular chemist's viewpoint, one of the most interesting differences between carbon and silicon is their divergent coordination behavior. In fact, silicon is prone to form hyper-coordinate organosilicon complexes, and, as conveyed by reports in the literature, highly sophisticated ligand systems are required to furnish low-coordinate organosilicon complexes. Tremendous progress in experimental, as well as computational, techniques has granted synthetic access to a broad range of coordination numbers for silicon, and the scientific endeavor, which was ongoing for decades, was rewarded with landmark discoveries in the field of organosilicon chemistry. Molecular congeners of silicon(0), as well as silicon oxides, were unveiled, and the prominent group 14 metalloid proved its applicability in homogenous catalysis as a supportive ligand or even as a center of catalytic activity. This book focuses on the most recent advances in the coordination chemistry of silicon with transition metals as well as main group elements, including the stabilization of low-valent silicon species through the coordination of electron donor ligands. Therefore, this book is associated with the development of novel synthetic methodologies, structural elucidations, bonding analysis, and also possible applications in catalysis or chemical transformations using related organosilicon compounds.

Keywords

silanetriols --- disiloxane tetrols --- silsesquioxanes --- condensation --- molecular cage --- platinum --- primary silane --- hydrido complex --- oxidative addition --- ligand-exchange reaction --- X-ray crystallography --- Si–Cl activation --- germylene --- digermene --- digermacyclobutadiene --- palladium --- cluster --- cyclic organopolysilane --- template --- bridging silylene ligand --- isocyanide --- hydrogen bonds --- silicon --- 2-silylpyrrolidines --- stereochemistry --- X-ray crystallography --- Baird’s rule --- computational chemistry --- excited state aromaticity --- Photostability --- dye-sensitized solar cell --- disilanylene polymer --- photoreaction --- surface modification --- TiO2 --- silylene --- germylene --- N-heterocyclic carbene --- oxidative addition --- siloxanes --- host-guest chemistry --- supramolecular chemistry --- main group coordination chemistry --- hydrogen bonding --- adsorption --- bond activation --- bonding analysis --- density functional theory --- distorted coordination --- molecular orbital analysis --- silicon surfaces --- disilene --- functionalization --- ?-electron systems --- silicon --- N-heterocyclic carbenes --- bromosilylenes --- silyliumylidenes --- dehydrobromination --- silicon cluster --- siliconoid --- nanoparticle --- computation --- silicon --- N-heterocyclic carbenes --- silyliumylidenes --- small molecule activation --- mechanistic insights --- organosilicon --- reductant --- N-Heterocyclic tetrylene --- salt-free --- germanium --- germanethione --- germathioacid chloride --- N-heterocyclic carbines --- ?-chloro-?-hydrooligosilane --- titanium --- ruthenium --- dehydrogenative alkoxylation --- cluster --- isomerization --- silicon --- siliconoid --- subvalent compounds --- AIM --- DFT --- intermetallic bond --- 29Si NMR spectroscopy --- X-ray diffraction

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