Nuclear Magnetic Resonance Spectroscopy Of Liquid Crystals

This edited volume provides an extensive overview of how nuclear magnetic resonance can be an indispensable tool to investigate molecular ordering, phase structure, and dynamics in complex anisotropic phases formed by liquid crystalline materials. The chapters, written by prominent scientists in their field of expertise, provide a state-of-the-art scene of developments in liquid crystal research. The fantastic assortment of shape anisotropy in organic molecules leads to the discoveries of interesting new soft materials made at a rapid rate which not only inject impetus to address the fundamental physical and chemical phenomena, but also the potential applications in memory, sensor and display devices. The review volume also covers topics ranging from solute studies of molecules in nematics and biologically ordered fluids to theoretical approaches in treating elastic and viscous properties of liquid crystals. This volume is aimed at graduate students, novices and experts alike, and provides an excellent reference material for readers interested in the liquid crystal research. It is, indeed, a reference book for every science library to have. Sample Chapter(s). Chapter 1: Novel Strategies for Solving Highly Complex NMR Spectra of Solutes in Liquid Crystals (1,464 KB). Contents: Novel Strategies for Solving Highly Complex NMR Spectra of Solutes in Liquid Crystals (E E Burnell et al.); Analytical Potentials of Natural Abundance Deuterium NMR Spectroscopy in Achiral Thermotropics and Polypeptide Chiral Oriented Solvents (P Lesot & C Aroulande); Noble Gas Probes in NMR Studies of Liquid Crystals (J Jokisaari); Bicelles OCo A Much Needed Magic Wand to Study Membrane Proteins by NMR Spectroscopy (R Soong et al.); Advances in Proton NMR Relaxometry in Thermotropic Liquid Crystals (P J Sebastiuo et al.); Deuterium NMR Study of Magnetic Field Distortions in Ferroelectric Mesogens (R Y Dong); Deuteron NMR Study of the Effects of Random Quenched Disorder in 12CB Silica Dispersions (D Finotello & V Pandya); Dynamics of Liquid Crystals by Means of Deuterium NMR Relaxation (C A Veracini & V Domenici); Translational Self-Diffusion Measurements in Thermotropics by Means of Statistic Field Gradients NMR Diffusometry (M Cifelli); Deuterium NMR Studies of Static and Dynamic Director Alignment for Low Molar Mass Nematics (A Sugimura & G R Luckhurst); Viscoelastic Properties of Liquid Crystals: Statistical-Mechanical Approaches and Molecular Dynamics Simulations (A V Zakharov); Carbon-13 NMR Studies of Thermotropic Liquid Crystals (R Y Dong); A Combined DFT and Carbon-13 NMR Study of a Biaxial Bent-Core Mesogen (A Marini et al.). Readership: Chemists, physicists and material scientists. In particular, NMR spectroscopists.

Intended for researchers and students in physics, chemistry and materials science, this book provides the necessary background information and sufficient mathematical and physical detail to study the current research literature. The book begins with a survey of liquid crystal phases and field effects, together with an introduction to the basic physics of nuclear magnetic resonance. It then discusses orientational ordering and molecular field theories for various liquid crystal molecules and nmr studies of uniaxial and biaxial phases. Subsequent chapters consider spin relaxation processes and rotational, translational, and internal molecular dynamics of liquid crystals. The final chapter discusses two-dimensional and multiple- quantum nmr spectroscopies and their application in elucidating liquid crystal properties. This second edition, updated throughout, incorporates many new references and includes new mathematical appendices.

The liquid crystalline state has been known for about a century and has been studied by many techniques. Nuclear magnetic resonance has been used to study mesophases for thirty years, but it has been in very recent years that advances in this form of spectroscopy have led to a rapid growth in its applications to the study both of liquid crystals and of solutes dissolved in them. It has become apparent that no other method of studying liquid crystals can yield such a wealth of data and it is unrivalled as a means of probing the behaviour of the molecules in mesophases. There has also been a steady increase in the study of the shape of small molecules dissolved in liquid crystals via the analysis of their NMR spectrum. In fact, the study of solutes was until recently regarded as a separate activity to the study of liquid crystals themselves, but this artificial division arose only from the gap between the large amount of information that could be derived from the spectrum of a small molecule and the rather meagre data set obtainable from the spectra of liquid crystals. This gap has, however, narrowed and it is now possible to derive a very detailed picture of the structure and orientational ordering of the large molecules typical of those which form liquid crystals. There has also been a rapid growth of interest in the liquid crystalline state.

NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions on internal motion studies, NMR spectra from quadpolar nuclei, and the anisotropy in nuclear spin-spin coupling. The final chapters review the theoretical and experimental studies on the anisotropy in chemical shifts, nematic rotation, and the nuclear magnetic double resonance. This book will prove useful to analytical chemists.

1. Lyotropic Liquid Crystals The class of compounds known as thermotropic liquid crystals has been widely utilized in basic research and industry during recent years. The properties of these materials are such that on heating from the solid to the isotropic liquid state, phase transitions occur with the formation of one or more intermediate anisotropic liquids. The unique and sometimes startling properties of these liquid crystals are the properties of pure compounds. However, there exists a second class of substances known as lyotropic liquid crystals which obtain their anisotropic properties from the mixing of two or more components. One of the components is amphiphilic, containing a polar head group (generally ionic or zwitterionic) attached to one or more long-chain hydrocarbons; the second component is usually water. Lyotropic liquid crystals occur abundantly in nature, particularly in all living systems. As a consequence, a bright future seems assured for studies on such systems. Even now, many of the properties of these systems are poorly understood. It is the purpose of this review to consolidate the results obtained from nuclear magnetic resonance studies of such systems and to provide a coherent picture of the field. Probably the most familiar example of a lyotropic liquid crystal is soap in water. A common soap is sodium dodecylsulphate where an ionic group (sulphate) is attached to a hydrocarbon chain containing twelve carbons.

Nuclear magnetic resonance spectroscopy, which has evolved only within the last 20 years, has become one of the very important tools in chemistry and physics. The literature on its theory and application has grown immensely and a comprehensive and adequate treatment of all branches by one author, or even by several, becomes increasingly difficult. This series is planned to present articles written by experts working in various fields of nuclear magnetic resonance spectroscopy, and will contain review articles as well as progress reports and original work, its main aim, however, is to fill a gap, existing in literature, by publishing articles written by specialists, which take the reader from the introductory stage to the latest development in the field. The editors are grateful to the authors for the time and effort spent in writing the articles, and for their invaluable cooperation. The Editors Contents P. Diehl and C. L. Khetrapal NMR Studies of Molecules Oriented in the Nematic Phase of Liquid Crystais......................................................... 1 R. G. Jones The Use of Symmetry in Nuclear Magnetic Resonance................. 97 NMR Studies of Molecules Oriented in the Nematic Phase of Liquid Crystals P. DIEHL and C. L. KHETRAPAL * Department of Physics, University of Basel, Switzerland Contents 1. Introduction . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Liquid Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . 2.1. Classification of Liquid Crystal Phases . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Theories of the Liquid Crystalline State . . . . . . . . . . . . . . . . . . . . . . 5 2.3. Nematic Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1 4. Basic Theory (for I = I ). . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . 7 . .

Dendrimers are hyperbranched molecules with well-defined nanometer-scale dimensions. Important technological applications of these systems, both in biomedicine and materials science, have been recently proposed. Liquid crystal dendrimers are fascinating materials that combine the characteristics of dendrimers with the anisotropic physical behaviour and molecular self-organization typical of liquid crystals. This unique association of physical and chemical properties, together with the possibility of multi-selective functionalization put forward by dendrimers, opens new perspectives for applications. Nuclear magnetic resonance (NMR) is a powerful experimental technique applied in materials science and an important tool to the study of molecular organization and dynamics. This book presents an introduction to dendrimers properties with special insight into liquid crystal dendrimers and a detailed description of the NMR theory and experimental techniques used in the investigation of these materials. It also discusses recent NMR research results on liquid crystal dendrimers, with emphasis on molecular order and dynamics studies. This book introduces the properties of dendrimers, with special insight into liquid crystal dendrimers, and a detailed description of NMR theory and experimental techniques used in the investigation of these materials. It also discusses results of recent NMR research on liquid crystal dendrimers, with an emphasis on molecular order and dynamics studies. Advanced undergraduate and graduate students of physics, chemistry, and materials science and researchers in the fields of dendrimers, liquid crystals, and NMR will find the book extremely useful.