Non-Covalent Interactions: Theory and Experiment (Rsc Theoretical and Computational Chemistry Series) - Hardcover

Hobza, Pavel; Muller-dethlefs, Klaus

Hardcover

ISBN 10: 1847558534 ISBN 13: 9781847558534

Verlag: Royal Society of Chemistry, 2010

Inhaltsangabe

The aim of this book is to provide a general introduction into the science behind non-covalent interactions and molecular complexes using some important experimental and theoretical methods and approaches. It is the first monograph on this subject written in close collaboration between a theoretician and an experimentalist which presents a coherent description of non-covalent interactions viewed from these two perspectives. The book describes the experimental and theoretical techniques, and some results obtained by these, which are useful in conveying the principles underlying the observable or computable properties of molecular clusters. The chemical and physical background underlying non-covalent interactions are treated comprehensively and non-covalent interactions is contrasted to ionic, covalent and metallic bonding. The role of dispersion and electrostatic interactions, static and induced multipole moments, charge transfer and charge localisation and de-localisation are described. In addition, the nomenclature and classification of non-covalent interactions and molecular clusters is discussed since there is still no unique agreement on it. The authors were among first who coined the term non-covalent for intermolecular interactions and all interactions can thus be categorised as metallic, covalent and non-covalent. The book covers covalent bonding where the properties of a moiety in a molecular cluster are concerned, for instance its electrostatic multipole moments. The historic development of the field is also briefly outlined, starting from van der Waals who first recognized the fact that molecules in the gas phase interact, through London who explained the fact that non-polar uncharged systems attract each other, making a connection to modern work of theoreticians and experimentalists who have contributed to the present knowledge in the field. The role of non-covalent interactions in nature is discussed and the book also argues why non-covalent interactions and not covalent ones play a key role in biological systems. The authors show the unique significance of non-covalent interactions in biological systems and describe several important processes (molecular recognition, structure of biomacromolecules, etc) that are fundamentally determined by non-covalent interactions. The book is aimed at undergraduate and graduate students who need to learn more about non-covalent interactions and their role in chemistry, physics and biology. It also provides valuable information to non-specialist scientists and also those who work in the area who will find it interesting reading. As both experimental and theoretical procedures are covered, this enables the reader to orientate themselves in this very intensely growing area.

Über diesen Titel

Über die Autorin bzw. den Autor

Professor Dr Pavel Hobza is at the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Prague, Czech Republic.

Professor Klaus Müller-Dethlefs is Chair of Chemistry and Chair of Physics, and Director of the Photon Science Institute, The University of Manchester, Manchester, UK.

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Non-covalent Interactions

Theory and Experiment

By Pavel Hobza, Klaus Müller-Dethlefs

The Royal Society of Chemistry

Copyright © 2010 Pavel Hobza and Klaus Müller-Dethlefs
All rights reserved.

ISBN: 978-1-84755-853-4

Contents

Chapter 1 Introduction, 1, 
Chapter 2 Characteristics of Non-covalent Complexes and Their Determination by Experimental and Theoretical Techniques, 21, 
Chapter 3 Potential-Energy and Free-Energy Surfaces, 70, 
Chapter 4 Classification of Non-covalent Complexes, 134, 
Chapter 5 Interpretation of Experimental Results and Types of Molecular Clusters, 155, 
Chapter 6 Extended Molecular Clusters in Chemistry, the Atmosphere and Stereospecific Molecular Recognition, 206, 
Subject Index, 221, 

CHAPTER 1

Introduction

1.1 An Historical Remark

It was none other than van der Waals, in the 1870s, who realised that the discrepancies observed between the state function of a real gas and the ideal gas law could be accounted for by the attracting forces between molecules or rare gas atoms. Van der Waals introduced an equation of state suitable for describing the behaviour of real (in contrast to ideal) gases. Although this law does not provide the most accurate functional description for a real gas, it nevertheless constituted a major breakthrough. Van der Waals made it explicitly obvious, for instance with respect to condensation of all real gases, that significant attracting forces exist between gas molecules (or atoms, in the case of monoatomic gases), which exhibit a tendency to form a new type of bond. An important landmark in the history of understanding these attracting forces is represented by the liquefaction of helium in experiments by Kamerlingh-Onnes. The very existence of liquid helium provides a most decisive argument about the existence of attractive intermolecular forces acting even between small spherical rare gas atoms such as helium, not bearing any charge or permanent electric multipole moment.

The formation of these special van der Waals bonds, compared to chemical bonds, is not energetically demanding at all; these bonds are, under general laboratory conditions, easily formed and just as easily split. What happens to appear as a weakness represents, surprisingly, a strength of such bonds. In the context of a scenario for the evolution of life on Earth it was necessary to find, besides strong covalent bonding, another type of much weaker bonding allowing easy reversibility of the formation process. The supermolecule formed should allow for repeating opening and closing without changing any important structural feature.

Many years later, in 1930, Fritz London (and soon afterwards Hans Hellmann) made a fundamental step in describing and interpreting these bonds. This was only possible using the recently born quantum mechanics. Though several contributions can be interpreted by classical physics, the most important ones giving rise to the repulsion and attraction between systems (exchange-repulsion and dispersion contributions, see later) that are of quantum origin and could be interpreted only by using the theoretical apparatus of quantum mechanics. Works of these and other pioneers are mentioned or outlined in the classic book on intermolecular interactions by J. O. Hirschfelder, C. F. Curtiss, and R. B. Bird, and a survey of monographs and reviews up to the mid-1980s is presented in a book on intermolecular complexes. Selected summarising works since about 1985 are presented in ref. 7. Specifically to be mentioned are three thematic issues of Chemical Reviews devoted to non-covalent interactions, which appeared in 1988, 1994 and 2000, and one thematic issue of Phys. Chem. Chem. Phys. devoted to the same subject in 2008; all these thematic issues were edited by one of us (PH). Besides these works three books need to be mentioned that supplement the present book. The first one by A. J. Stone focuses on the theory of non- covalent interactions and perturbation calculations of the cluster interaction energy. The second one by A. Karshikoff describes non-covalent interactions in proteins. The third one by I. G. Kaplan deals with the theory and computation of intermolecular interactions. The book presented here is largely based on our theoretical and experimental papers published in the last two decades, which are cited at the end of each chapter. A special place is held by our recent review entitled, "The World of Non-covalent Interactions: 2006" by both present authors and Rudolf Zahradnik.

1.2 A Remark on Nomenclature of Molecular Complexes

Why are molecular complexes, or molecular clusters, as they are most often called, of such interest? The main feature of molecular clusters is that they can be prepared experimentally in supersonic jet expansions and molecular beams as isolated systems exhibiting intermolecular bonds that originate from non-covalent interactions. From the theoretical point of view molecular clusters can also be studied using standard ab initio quantum-chemical methods, treating the cluster as a "supermolecule" composed of several moieties held together by non-covalent bonds.

An issue in the literature that sometimes is unclear relates to the definition of non-covalently bound complexes. A significant feature of such complexes is that the subsystems, of which they are constituted, are not bound by covalent interactions but solely by electric multipole-electric multipole interactions. We consider, however, not only permanent, but also inductive, and time-dependent multipoles. While it is possible to ascribe the stability of a complex to a bond, non-covalent in nature, it is not always easy to localise such a bond in space. When possible it is highly desirable to use another symbol for this bond than that which represents a covalent bond, i.e. a short full line – hence, three dots ... may serve as a representation of a non-covalent bond. The hydrogen molecule and the helium (van der Waals) molecule are adequate representatives: H–H and He ... He, or alternatively H2 and (He)2.

The second type of bond illustrated above still does not have a definite name. No doubt, it is possible to call it a non-covalent bond. Another label, which is sometimes used, is derived from the term weak interactions and therefore the name "weak bonds" is used. This is an unfortunate name, because it is derived from a designation that has been used for a long time in physics in a completely different context. We have favoured for years the designation "van der Waals" (vdW in abbreviated form), e.g., vdW interactions, forces, bonds. It is unfortunately true that this designation has been corrupted – sometimes by poorly defined use – for a component of the empirical force field. In the case of empirical potentials the vdW term means a sum of London dispersion and exchange-repulsion terms. In our previous review we decided to use the term "non-covalent" to classify interactions that are not covalent. We are aware that this definition is again not straightforward and unambiguous since, for example, metallic interactions are also covered but we believe that the term non-covalent properly describes the origin and nature of these interactions. In the very broadest sense non-covalent interactions include electrostatic interactions between permanent multipoles (charge-charge, charge-dipole, charge-multipole, multipole-multi-pole ...), induction and/or polarisation interactions between permanent and induced multipoles,...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2010
• Sprache: Englisch
• ISBN 10: 1847558534
• ISBN 13: 9781847558534
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 225
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: Nicht verfügbar