Download or read book High Resolution NMR Spectroscopy Understanding Molecules and their Electronic Structures written by and published by Newnes. This book was released on 2013-06-08 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progress in nuclear magnetic resonance (NMR) spectroscopy that took place during the last several decades is observed in both experimental capabilities and theoretical approaches to study the spectral parameters. The scope of NMR spectroscopy for studying a large series of molecular problems has notably broadened. However, at the same time, it requires specialists to fully use its potentialities. This is a notorious problem and it is reflected in the current literature where this spectroscopy is typically only used in a routine way. Also, it is seldom used in several disciplines in which it could be a powerful tool to study many problems. The main aim of this book is to try to help reverse these trends.This book is divided in three parts dealing with 1) high-resolution NMR parameters; 2) methods for understanding high-resolution NMR parameters; and 3) some experimental aspects of high-resolution NMR parameters for studying molecular structures. Each part is divided into chapters written by different specialists who use different methodologies in their work. In turn, each chapter is divided into sections. Some features of the different sections are highlighted: it is expected that part of the readership will be interested only in the basic aspects of some chapters, while other readers will be interested in deepening their understanding of the subject dealt with in them. Shows how NMR parameters are useful for structure assignment as well as to obtain insight on electronic structures Emphasis on conceptual aspects Contributions by specialists who use the discussed methodologies in their everyday work
Download or read book High Resolution NMR Spectroscopy written by Gustavo A. Aucar and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polarization propagators (PP) are powerful theoretical tools that allow carrying out a deep analysis of the electronic mechanisms underlying any molecular response property. The inner projections of the PP and contributions from localized orbitals within the PP approaches described in were developed to fully take advantage of this power of analysis for the study of NMR spectroscopic parameters. They are based on the use of localized molecular orbitals (LMOs) related to chemically intuitive concepts to decompose the mathematical expression of these parameters into coupling pathways or shielding pathways. Each of them may be furthermore decomposed into two new objects: (i) perturbators, which give information on the efficiency of a given magnetic perturbation to produce local excitations and (ii) the principal propagator matrix elements which provide deep understanding on the way perturbations are transmitted within the electronic framework of the molecule under study. Applications are presented in , both within semiempirical and ab initio approaches: the Karplus rule, a general analysis of the signs of J couplings, σ–π decomposition, hyperconjugative effects in transmission of J couplings, general features of 1J couplings, and intermolecular couplings in hydrogen-bonded systems. All applications were especially selected to cover examples in which qualitative physical insight can be gained.
Download or read book High Resolution NMR Spectroscopy written by Rubén H. Contreras and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this introductory chapter are described briefly the aims and scopes of this multiauthor book. One of the main ideas behind them is helping its readership to understand some approaches for extracting information on subtle chemical interactions, defining trends of such parameters from either measured or calculated high-resolution NMR parameters (indirect nuclear spin–spin coupling constants and nuclear magnetic shielding constant) without needing to acquire solid backgrounds on quantum chemistry. However, in all cases, the discussed ideas are based on solid grounds, and adequate references are quoted for readers interested in a better understanding of the basic concepts lying behind such approaches. It is highlighted that such discussions are restricted only to a few methods in order to both avoid overlapping this book with descriptions found in the current literature and to avoid lengthening this book beyond reasonable limits. It was also considered pertinent to include chapters dealing with concepts whose importance are increasing rapidly in modern NMR spectroscopy like for instance, relativistic effects on NMR parameters in compounds containing heavy atoms, and NMR spectroscopy in paramagnetic species, pNMR. Also, it was considered opportune including in this book excellent examples showing how very good excellent sets of experimental values can provide interesting insight in some chemical interactions.
Download or read book High Resolution NMR Spectroscopy written by P. Lazzeretti and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Ramsey theory of nuclear magnetic resonance spectral parameters has been reformulated in terms of current densities induced in the electron cloud of a molecule by an external magnetic field and intramolecular magnetic dipoles at the nuclei. Conditions for invariance of nuclear magnetic shielding and nuclear spin–spin coupling tensors, in gauge transformations of the vector potentials associated to the magnetic perturbations, have been expressed via quantum mechanical sum rules, also providing constraints for charge conservation. It is shown that the combined use of current density and property density maps provides valuable tools for the rationalization of magnetic response.
Download or read book High Resolution NMR Spectroscopy written by Krystyna Kamieńska-Trela and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter is devoted to the 1–3JCCs and to the factors influencing their magnitude. The experimental and calculated J data presented in the subsequent parts of the chapter are arranged with the thought of showing how hybridization, substituent electronegativity, the complex and hydrogen bond formation, and geometry of the compound bear on the JCC magnitude and which range of changes can be expected for a given type of coupling when all these effects are taken into account. The subsequent sections are devoted to the couplings across single, double, and triple CC bonds and to the couplings in aromatic and heteroaromatic systems and in the compounds of biological importance. It is also shown that at the present level of theory, it is possible in many cases to reproduce the experimental J values very exactly, achieving one-to-one correspondence.
Download or read book High Resolution NMR Spectroscopy written by Jean-Cyrille Hierso and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin–spin coupling constant J provides decisive data for organic compound characterization. This electron-mediated coupling is usually taught as transmitted between covalently bonded magnetic atoms. However, this physical interaction between nuclear spins is much more complex than that with regard to chemical bonding concept. Independent experimental and theoretical studies related to small organic and organometallic species (molecular mass below 2000gmol−1) have highlighted the existence of J couplings operating via clearly nonbonded interactions and known as “through-space” couplings. Interactions of this type are frequently reported and couplings involving 19F, 13C, 77Se, 15N, 31P, or 1H in hydrogen bonding are now clearly identifiable. This chapter aims to clarify this phenomenon often poorly known by routine users of NMR. Thus, nonbonded spin couplings can provide critical data for studying and determining molecular structures both in solution and in the solid state. This is illustrated herein through selected examples picked in different families of small organic and organometallic compounds.
Download or read book High Resolution NMR Spectroscopy written by Rubén H. Contreras and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This chapter describes briefly chemical shifts (or nuclear magnetic shielding constants) and indirect spin–spin coupling constants. They are well known as powerful tools for studying several molecular properties which are very important in different branches of the broad field of molecular sciences. The present description is oriented to an interdisciplinary audience and therefore it is expected that it can be followed for readers without strong backgrounds either in mathematics or physics. After a short revision of basic concepts, a qualitative method devised to extract information on electronic molecular structures is described. This aim is achieved employing this qualitative method for relating such parameters known in different series of compounds with several common chemical interactions. Since both types of NMR parameters present second-rank tensor properties, it is discussed how such property is affected in molecules measured in isotropic phase. Anybody with mathematical and physical background would answer immediately, “in isotropic phase is only observed one-third of the respective tensor trace.” However, in molecules that trace depends on the relative orientation of the Principal Axes System and bonds associated to the atom whose nuclear magnetic shielding is studied, or to the straight line connecting a pair of coupled nuclei. To describe these effects in this chapter is coined the expression “the geometric effect” to identify them. The same expression is also employed in . A list of exercises and appropriate references are included at the end of this chapter.
Download or read book High Resolution NMR Spectroscopy written by Jochen Autschbach and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: For heavy atoms, and for molecules with heavy atoms, a theoretical description of the electronic structure needs to consider the finite speed of light and Einstein’s special relativity. This chapter provides a brief introduction to special relativity and to relativistic methods in quantum chemistry. It is shown how these methods can be used to calculate NMR chemical shifts and indirect spin–spin coupling constants (J-coupling). A number of examples are discussed where relativistic effects have a significant influence on these NMR parameters. In some cases for example, for indirect spin–spin coupling involving 199Hg, relativistic effects may be larger than the total value calculated with a nonrelativistic method.
Download or read book High Resolution NMR Spectroscopy written by J.M. García de la Vega and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural bond orbital and natural J-coupling methods are used for the analysis of the Fermi-contact contributions to spin–spin coupling constant (SSCC). In this way, the SSCCs are partitioned into three contributions: Lewis, delocalization, and repolarization. This partition is applied to the study of some chemical systems to explain the main electron delocalization effects on SSCCs.
Download or read book High Resolution NMR Spectroscopy written by Juha Vaara and published by Elsevier Inc. Chapters. This book was released on 2013-06-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory and quantum-chemical calculations of the spectral parameters of nuclear magnetic resonance (NMR) are well established in the case of diamagnetic, closed-shell molecules. In contrast, NMR calculations of paramagnetic, open-shell molecules (pNMR) are scarce, limited by both assumptions within the underlying theoretical background as well as the availability of computational implementations. We discuss the systematic development of pNMR theory that recently culminated in a novel, general and systematic electronic structure approach for the shielding tensor and the associated chemical shift for paramagnetic, open-shell atoms, molecules, and nonmetallic solids. The approach has now been extended for the first time to a higher than doublet spin state as well as arbitrary spatial symmetry. The approach is formulated without reference to spin susceptibility, in contrast to the contemporary experimental procedure and approximate quantum-chemical treatment of axial zero-field splitting. As a result of the systematic procedure, all the temperature-dependent hyperfine shielding terms are generalized and, for example, the leading-order nonrelativistic dipolar term now provides an isotropic chemical shift contribution for species with triplet and higher spin multiplicity. Recent first-principles quantum-chemical calculations of pNMR chemical shifts are reviewed both using the novel theory as well as earlier approaches.
Download or read book Annual Reports on NMR Spectroscopy written by and published by Academic Press. This book was released on 2019-01-26 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annual Reports on NMR Spectroscopy, Volume 96, provides an in-depth accounting of progress in nuclear magnetic resonance (NMR) spectroscopy and its many applications, including all branches of science in which precise structural determination is required, and in which the nature of interactions and reactions in solution is being studied. This book has established itself as a premier resource for both specialists and non-specialists, with this new release focusing on Recent Advances in Absolute Shielding Scales for NMR Spectroscopy, Applications of Hyperpolarus Long-Lived States in Drug Screening, and Characterization of Mixed Network Phosphate Classes by 1D and 2D NMR Techniques, amongst other topics. Serves as the premier resource for learning the new techniques and applications of NMR spectroscopy Provides a key reference for chemists and physicists using NMR spectroscopy to study the structure and dynamics of molecules Covers all aspects of molecular science, including MRI (Magnetic Resonance Imaging)
Download or read book Nuclear Magnetic Resonance written by and published by Royal Society of Chemistry. This book was released on 2014-05-21 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in its 43rd volume, the Specialist Periodical Report in Nuclear Magnetic Resonance presents comprehensive and critical reviews of the recent literature, providing the reader with an informed summary of the field from invited authors. Several chapters in this volume are devoted to biochemistry, focussing on carbohydrates, lipids, and proteins and nucleic acids; Malcolm Prior also presents a chapter examining the recent literature of NMR in living systems and Cynthia Jameson reviews the theoretical and physical aspects of nuclear shielding, while Jaroslaw Jazwinski examines the theoretical aspects of spin-spin couplings. The lead volume editor, Krystyna Kamienska-Trela, presents a chapter on the applications of spin-spin couplings. Anyone wishing to update themselves on the recent and hottest developments in NMR will benefit from this volume, which deserves a place in any library or NMR facility. Purchasers of the print edition can register for free access to the electronic edition by returning the enclosed registration card.
Download or read book High Resolution NMR written by Edwin D. Becker and published by Elsevier. This book was released on 2012-12-02 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Resolution NMR: Theory and Chemical Applications discusses the principles and theory of nuclear magnetic resonance and how this concept is used in the chemical sciences. This book is written at an intermediate level, with mathematics used to augment verbal descriptions of the phenomena. This text pays attention to developing and interrelating four approaches – the steady state energy levels, the rotating vector picture, the density matrix, and the product operator formalism. The style of this book is based on the assumption that the reader has an acquaintance with the general principles of quantum mechanics, but no extensive background in quantum theory or proficiency in mathematics is required. This book begins with a description of the basic physics, together with a brief account of the historical development of the field. It looks at the study of NMR in liquids, including high resolution NMR in the solid state and the principles of NMR imaging and localized spectroscopy. This book is intended to assist chemistry graduate students, advanced undergraduate students, or researchers to understand NMR at a fundamental level. This text also provides illustrations of the applications of NMR to the determination of the structure of small organic molecules and macromolecules, including proteins.
Download or read book Gas Phase NMR written by Karol Jackowski and published by Royal Society of Chemistry. This book was released on 2016-02-09 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the recent NMR studies with the application of gaseous molecules. Among the comprehensively discussed aspects of the area it includes in particular: new multinuclear experiments that deliver spectral parameters of isolated molecules and provide the most accurate values of nuclear magnetic shielding, isotropic spin–spin coupling and relaxation times; advanced, precise and correct theoretical descriptions of spectral parameters of molecules as well as the application of gas-phase NMR measurements to chemical analysis and medicine. The progress of research in these fields is enormous and has rapidly changed our knowledge and understanding of molecular parameters in NMR spectroscopy. For example, accurate studies of the shielding for isolated molecules allow the exact determination of nuclear magnetic dipole moments, the calculated values of spectral parameters can be verified by precise gas-phase NMR measurements, and the application of hyperpolarized noble gases provides excellent MRI pictures of lungs. Aimed at graduates and researchers in spectroscopy, analytical chemistry and those researching the applications of NMR in medicine, this book presents the connections between sophisticated experiments, the theory of magnetic parameters and the exploration of new methods in practice.
Download or read book High Resolution NMR Techniques in Organic Chemistry written by Timothy D.W. Claridge and published by Newnes. This book was released on 2009 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Nuclear Magnetic Resonance (NMR) Spectroscopy remains the foremost analytical technique for the structure elucidation of organic molecules and an indispensable tool for the synthetic, medicinal and natural product chemist. New techniques continue to emerge and the application of NMR methods continues to expand. High-Resolution NMR Techniques in Organic Chemistry is designed for use in academic and industrial NMR facilities, as a text for graduate-level NMR courses, and as an accessible reference for the chemist's or spectroscopist's desk."--BOOK JACKET.
Download or read book Structure of High Resolution NMR Spectra written by P.L. Corio and published by Elsevier. This book was released on 2012-12-02 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structure of High-Resolution NMR Spectra provides the principles, theories, and mathematical and physical concepts of high-resolution nuclear magnetic resonance spectra. The book presents the elementary theory of magnetic resonance; the quantum mechanical theory of angular momentum; the general theory of steady state spectra; and multiple quantum transitions, double resonance and spin echo experiments. Physicists, chemists, and researchers will find the book a valuable reference text.
Download or read book Methods for Structure Elucidation by High Resolution NMR written by G. Batta and published by Elsevier. This book was released on 1997-12-04 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear Magnetic Resonance Spectroscopy (NMR) is now widely regarded as having evolved into a subscience. The field has become immensely diverse, ranging from medical use through solid state NMR to liquid state applications, with countless books and scientific journals devoted to these topics. Theoretical as well as experimental advance continues to be rapid, and has in fact accelerated by many novel innovations. This multi-authored book focuses on the latest developments in the rapidly evolving field of high resolution NMR, specifically with a view to applications on the structure elucidation of organic molecules of moderate molecular weight. Conceptually it differs from basic educational texts, hard-core scientific papers and regular review articles in that each chapter may be regarded as the authors' personal account of their special insights and results that crystallised after several years of research into a given topic. The book revolves around several themes and offers a handful of scientific "gems" of various colors, reflecting the great diversity of NMR. It contains 16 loosely connected chapters written by some of today's most accomplished NMR scientists in the world. Each chapter is a unique synthesis of the authors' previous research results in the given field, and thus projects special insights. Much emphasis has been given to the latest developments in NMR, in particular to selective pulses and pulsed field gradients. As a part of the series "Analytical Spectroscopy Library", with subsequent editions coming along this book should provide a platform for future research accounts of similar flavor. The material is presented in a mostly non-mathematical fashion, and is intended mainly for chemists, application NMR scientists and students with already some background in NMR. Some of the chapters slightly overlap in the discussed topics, which is particularly exciting in terms of gaining insight into the same area from different angles.
