Foreword

The progress made in instrumental analytical chemistry over the past two decades has been staggering. It is thus timely to present another comprehensive treatise on some of the most powerful tools from the chemist's arsenal that can be used to answer questions on the molecular properties of matter. Professor Yong-cheng Ning, one of the leading spectroscopists in China, has made a wise selection of the techniques to be included: nuclear magnetic resonance, mass spectrometry and infrared and Raman spectroscopy. All are treated in great depth and provide a sound basis of understanding, but the discussion is still comprehensible to chemists interested in their own immediate application. Many instructive examples are presented, illustrating detailed spectral analysis of organic compounds. The book is well balanced and will prove to be extremely useful to a wide range of experimental scientists.

Indeed, chemical analysis is widespread in almost all sciences. It has certainly become indispensable in materials science for establishing structure-property relationships. The deeper the understanding of biochemical and life processes, the more chemical concepts are required for explanations, and it has become apparent that biochemistry represents just an advanced form of the chemistry of complex systems. Instrumental analysis tools have profoundly changed molecular biology over recent decades. Even in biomedicine, the same techniques have proved to be very insightful. Instrumental chemical analysis has truly become one of the basic pillars of modern science.

Not without good reason, four chapters of the book deal with nuclear magnetic resonance (NMR). Indeed, NMR has proved to be one of the most versatile analytical tools to be developed so far. Its adaptability to a wide range of applications is quite remarkable, and even after almost 60 years of development, it is still being utilized in novel and more sophisticated applications, particularly in the understanding of the function of larger and larger biopolymers. Certainly, mastering advanced pulse sequences is one of the secrets of the progress of NMR. These aspects are treated well and extensively in this book.

Organic mass spectrometry has also made remarkable progress over recent decades. It has become an invaluable tool for determining the primary structure of from small up to very large molecules. In addition, it is a wonderful tool for exploring ion reactions in the gas phase. With the development of powerful ionization techniques of molecules, almost without any size limitations, mass spectrometry has become one of the most important tools in organic chemistry and in molecular biochemistry.

Infrared (IR) and Raman spectroscopy are certainly the most traditional of the techniques mentioned, developed during the first half of the twentieth century. Although some of the traditional fields of application have been challenged by NMR and mass spectrometry, IR and Raman have maintained their importance as fast and convenient tools of analysis. In addition, progress in the optical domain over recent decades has continued and even accelerated, and today no chemist can operate successfully without access to optical spectroscopy.

Even more important than the individual tools is their wise combination. Today, too many specialists only know their own work horse and try to apply it to all conceivable problems. Breaking the barriers between the various fields and applying the entire arsenal of tools will be essential to further progress. In this respect, the treatise by Professor Yong-cheng Ning is very welcome. It can open the so far closed windows between the various analytical techniques and perhaps further fertilize better coordinated progress in instrumental analysis.

Preface

Structural Identification of organic compounds using a combination of various spectroscopic data is undoubtedly a very important area of work for chemists. Organic spectroscopy is now a highly developed and still rapidly evolving discipline. Chemists should know of any up-to-date developments so that they can apply advanced techniques in their own research. Of course they hope to understand the principles, advantages and application limits of any new techniques. Furthermore, they need to know that spectra are dependent on measuring conditions. For example: the peaks of quaternary carbon atoms could be lost in their ¹³C spectrum when the delay between two pulses is not long enough; there are artifacts in 2D NMR spectra; the molecular ion peak of a measured compound could be missed in its mass spectrum when using electron ionization, etc. Chemists can correctly interpret spectra only on the basis of having essential knowledge of the organic spectroscopy.

Organic spectroscopy is an inter-discipline between physics and chemistry. It is based on physics. At present many monographs on nuclear magnetic resonance, mass spectrometry and infrared spectroscopy written by physicists are difficult for chemists to understand. In addition, these books may be far removed from the chemical application of the spectroscopic techniques. On the other hand, monographs written by chemists emphasize the interpretation of spectra, but they do not discuss the physical basis of organic spectroscopy in any great detail. There is thus a gap between these two types of monographs.

This monograph presents the principles of organic spectroscopy in great depth in simple terms, and it builds a bridge between these two types of monographs. Chemists will gain a deeper understanding of the principles of organic spectroscopy with this monograph. A typical example is the discussion on pulse sequence units that construct pulse sequences for 2D NMR. The principles of the pulse sequence units are presented in a way that is easy for readers to understand. Once the functions of the units have been mastered, the principles of related pulse sequences, which consist of these units, can be better appreciated. Further discussion of this is presented in Appendix 1, "Product Operator Formalism for Pulse Sequences".

Up-to-date developments in NMR, MS, IR and Raman are covered in the book, for example, the pulsed-field gradient technique, LC-NMR, DOSY, the interpretation of mass spectra produced by soft ionization techniques, 2D IR, which can be verified from Appendix 3, "Subject Index (Spectroscopic Methods and Theories)". The material has been prepared from the latest literature and information provided by manufacturers of spectroscopic instruments.

Although considerable space in the book is devoted to the discussion of spectroscopic theories, key tricks for the interpretation of spectra, including some of the author's original ideas, are treated thoroughly. For instance, the analysis of split patterns of peaks in the ¹H spectrum is more important and reliable than that of chemical shifts, which is illustrated by many examples. In addition, the book summarizes the rules for the interpretation of spectra and the spectroscopic patterns of common functional groups. The interpretation of spectra is always given in detail, especially for ¹H spectra. The monograph provides abundant spectral data so that it is convenient for the reader to deduce an unknown structure from the spectra of the compound.

A whole chapter deals with the determination of configurations and conformations of organic compounds and some biological molecules. It should be stressed that the discussions are presented from the point of view of spectroscopic methodology.

This book will be very useful for chemists who are engaged in research on organic structures as well as graduate students of related specialities. In fact, the book is an updated translation of the Chinese version. The First Edition won a second-class prize for "Excellent Teaching Materials" from the State Education Commission of China in 1992. The Second Edition was selected as one of the excellent textbooks for graduate students by the Ministry of Education of China in June 2003. Only two books from the field of chemistry were selected at the time. More than 16500 copies have been sold-out in the mainland of China. It has also been printed twice in complex Chinese characters in Taiwan.

The author wishes to express his deepest gratitude to Prof. Dr. Richard R. Ernst, the single Nobel Prize winner for chemistry in 1991, who wrote the Foreword to this book. The success of the Chinese version of the book can, to a considerable extent, be attributed to his first Foreword. It is certain that his second Foreword to the present version will continue to play an important role.

The author would like to record his sincere thanks to Prof. Di-hui Qing of the Department of Foreign Languages, Xidian University, and his graduate students, Miss Wen-ning Tong, Miss Yan-ping Xu, Miss Yan-ping Wang, Miss Zhi-hong Cao, Miss Yuan Yuan and Mr. Chang-an Li, who have checked and refined the manuscript. The English version is closely related to their work.

My gratitude is also extended to Professor Chun-tao Che of the Chinese University of Hong Kong, who provided about 30 spectra for the book and some examples in Sections 8.4 and 3.5.

The work of Mr. Hai-jun Yang, who was in charge of producing the figures electronically, is also greatly appreciated.

Last but not least, the author would like to express his sincere thanks to Bruker, Varian, JEOL, Micromass (VG), Finnigan-Mat, Applied Biosystems, Hewlett Packard, Bio-rad, Nicolet, Perkin Elmer, Shimadzu, Hitachi, Dilor, Ionspect and Bear. The book would not have been completed without their contributions to the latest developments in organic spectroscopy.