Equilibrium Molecular Structures

Molecular structure is the most basic information about a substance, determining most of its properties. Determination of accurate structures is hampered in that every method applies its own definition of "structure" and thus results from different sources can yield significantly different results. Sophisticated protocols exist to account for these

The properties of chemical, pharmaceutical, and biological compounds depend mainly on their molecular structure, whose determination is of fundamental interest. This book examines and systematizes more than three hundred striking structural determinations of free molecules. Featuring high-quality structural data and presenting modern techniques of their determinations by quantum chemistry, high-resolution spectroscopy and electron diffraction, the book is an indispensable resource for graduate students and professional scientists specializing in structural chemistry and other related fields.

This book examines around 400 of the most striking examples of structural studies of free molecules—selected and analyzed by virtue of the unique molecular complexity and novelty of the experimental techniques used. The properties of chemical, pharmaceutical, and biological compounds depend mainly on their molecular structure, the determination of which is of fundamental interest. Featuring high-quality structural data determined using modern techniques in electron diffraction and high-resolution spectroscopy, the book is an indispensable resource for graduate students and professional scientists specializing in structural chemistry and other relevant fields.

This book presents a detailed look at experimental and computational techniques for accurate structure determination of free molecules. The most fundamental property of a molecule is its structure – it is a prerequisite for determining and understanding most other important properties of molecules. The determination of accurate structures is hampered by a myriad of factors, subjecting the collected data to non-negligible systematic errors. This book explains the origin of these errors and how to mitigate and even avoid them altogether. It features a detailed comparison of the different experimental and computation methods, explaining their interplay and the advantages of their combined use. Armed with this information, the reader will be able to choose the appropriate methods to determine – to a great degree of accuracy – the relevant molecular structure.

A must-have resource that covers everything from out-of-equilibrium chemical systems and materials to dissipative self-assemblies Out-of-Equilibrium Supramolecular Systems and Materials presents a comprehensive overview of the synthetic approaches that use supramolecular bonds in various out-of-thermodynamic equilibrium situations. With contributions from noted experts on the topic, the text contains information on the design of dissipative self-assemblies that maintain their structures when fueled by an external source of energy. The contributors also examine molecules and nanoscale objects and materials that can produce mechanical work based on molecular machines. Additionally, the book explores non-equilibrium supramolecular polymers that can be trapped in kinetically stable states, as well as out-of-equilibrium chemical systems and oscillators that are important to understand the emergence of complex behaviors and, in particular, the origin of life. This important book: Offers comprehensive coverage of fields from design of dissipative self-assemblies to non-equilibrium supramolecular polymers Presents information on a highly emerging and interdisciplinary topic Includes contributions from internationally renowned scientists Written for chemists, physical chemists, biochemists, material scientists, Out-of-Equilibrium Supramolecular Systems and Materials is an indispensable resource written by top scientists in the field.

From the beginnings of modern chemistry, molecular structure has been a lively area of research and speculation. For more than half a century spectroscopy and other methods have been available to characterize the structures and shapes of molecules, particularly those that are rigid. However, most molecules are at least to some degree non-rigid and this non-rigidity plays an important role in such diverse areas as biological activity, energy transfer, and chemical reactivity. In addition, the large-amplitude vibrations present in non-rigid molecules give rise to unusual low-energy vibrational level patterns which have a dramatic effect on the thermodynamic properties of these systems. Only in recent years has a coherent picture of the energetics and dynamics of the conformational changes inherent in non-rigid (and semi-rigid) molecules begun to emerge. Advances have been made in a number of different experimental areas: vibrational (infrared and Raman) spectroscopy, rotational (microwave) spectroscopy, electron diffraction, and, most recently, laser techniques probing both the ground and excited electronic states. Theoretically, the proliferation of powerful computers coupled with scientific insight has allowed both empirical and ab initio methods to increase our understanding of the forces responsible for the structures and energies of non-rigid systems. The development of theory (group theoretical methods and potential energy surfaces) to understand the unique characteristics of the spectra of these floppy molecules has also been necessary to reach our present level of understanding. The thirty chapters in this volume contributed by the key speakers at the Workshop are divided over the various areas. Both vibrational and rotational spectroscopy have been effective at determining the potential energy surfaces for non-rigid molecules, often in a complementary manner. Recent laser fluorescence work has extended these types of studies to electronic excited states. Electronic diffraction methods provide radial distribution functions from which both molecular structures and compositions of conformational mixtures can be found. Ab initio calculations have progressed substantially over the past few years, and, when carried out at a sufficiently high level, can accurately reproduce (or predict ahead of time) experimental findings. Much of the controversy of the ARW related to the question of when an ab initio is reliable. Since the computer programs are readily available, many poor calculations have been carried out. However, excellent results can be obtained from computations when properly done. A similar situation exists for experimental analyses. The complexities of non-rigid molecules are many, but major strides have been taken to understand their structures and conformational processes.

Chemistry 2e is designed to meet the scope and sequence requirements of the two-semester general chemistry course. The textbook provides an important opportunity for students to learn the core concepts of chemistry and understand how those concepts apply to their lives and the world around them. The book also includes a number of innovative features, including interactive exercises and real-world applications, designed to enhance student learning. The second edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Substantial improvements have been made in the figures, illustrations, and example exercises that support the text narrative. Changes made in Chemistry 2e are described in the preface to help instructors transition to the second edition.

This textbook introduces the molecular side of physical chemistry. It offers students and practitioners a new approach to the subject by presenting numerous applications and solved problems that illustrate the concepts introduced for varied and complex technical situations. The book offers a balance between theory, tools, and practical applications. The text aims to be a practical manual for solving engineering problems in industries where processes depend on the chemical composition and physical properties of matter. The book is organized into three main topics: (I) the molecular structure of matter, (II) molecular models in thermodynamics, and (III) transport phenomena and mechanisms. Part I presents methods of analysis of the molecular behavior in a given system, while the following parts use these methods to study the equilibrium states of a material system and to analyze the processes that can take place when the system is in a state of non-equilibrium, in particular the transport phenomena. Molecular Physical Chemistry for Engineering Applications is designed for upper-level undergraduate and graduate courses in physical chemistry for engineers, applied physical chemistry, transport phenomena, colloidal chemistry, and transport/transfer processes. The book will also be a valuable reference guide for engineers, technicians, and scientists working in industry. Offers modeling techniques and tools for solving exercises and practical cases; Provides solutions and conclusions so students can follow results more closely; Step-by-step problem solving enables students to understand how to approach complex issues.