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........ published in NEWSLETTER # 66

Excerpt from preface by Professor J. Michl, Dept. of Chemistry and Biochemistry, University of Colorado, Boulder/CO (U.S.A.)

In recent years, there has been increasing interest among chemists, physicists, materials scientists, biologists, engineers, and others in the assembly of well defined, relatively large functional structures from repetitive units that themselves are molecules of some complexity. Using the dictionary definition of a module (a detachable section, compartment, or unit with a specific purpose or function, and in electronics, a compact assembly functioning as a component of a larger unit) (1), we feel that this newly emerging field or endeavor could be called "modular chemistry" (2).

The NATO Advanced Research Workshop on Modular Chemistry held in September 1995, at Aspen Lodge near Estes Park, Colorado (U.S.A.) was meant to bring together prominent contributors to modular chemistry as it is being born, and to examine the associated birth pangs. It was concluded that although real, there are not nearly as bad as giving birth to a hedgehog tail first, and that the ultimate rewards were likely to be far more satisfying in terms of new ideas and enabling methodology. The level of excitement about the possibilities that are opening up for modular chemists, and also the challenge involved, are perhaps best documented by noting that the planned discussion periods at the workshop were as long as the oral presentation periods, and yet, each discussion ran over the allocated time.

Perhaps the most striking, and most useful aspect of the workshop was its interdisciplinary nature. The participants came from a variety of subdisciplines that seem to be combining to create the new field of modular chemistry. In spite of these widely differing backgrounds, and perhaps precisely because of them, the participants clearly relished listening to each other and debating thereafter.

The two most visible sources from which modular chemistry originates are supramolecular ("self-assembly") chemistry, which exploits non-covalent intermolecular forces among modules to form larger assemblies, and polymer chemistry, which is based on attaching modules to each other through covalent bonds. However, many of the participating practitioners of modular chemistry consider themselves neither supramolecular nor polymer chemists. Some are primarily crystallographers, others are solid-state chemists or physicists, small-molecule organic chemists, inorganic coordination or main group chemists, photochemists or photophysicists, surface chemists, electrochemists, carbon or semiconductor cluster chemists, biochemists, biomimetic chemists, biomineral chemists, materials scientists, microscopists, or theoreticians, while still others work in "molecular electronics", in non-linear optics, with Langmuir-Blodgett or self-assembled monolayers, or with liquid crystals.

The size of the modules also varies enormously, from less than one nanometer across to nearly macroscopic. The concept of a hierarchy of structures of increasing size was referred to repeatedly, and comparisons were inevitably made with the organization of living matter. There is clearly much that is being learnt from biology, yet we also heard much from participants whose research programs consciously focus on structures that have no known analogues in living matter.

The present volume (NATO ASI SERIES C499) represents an attempt to capture the tantalizing atmosphere of the workshop as faithfully as possible, and to provide a record of what modular chemistry looked like close to the time of its birth. The authors were encouraged to be just as daring, provocative, and speculative in their written contributions as they had been in their oral or poster presentations at the workshop. They were asked not to provide reviews of previously published material but to concentrate on the newest ongoing research in their laboratories, even if it is still incomplete and the results not quite understood. They were asked to include their views on where modular chemists stand, where they are going, and what they propose to do once they get there. All of the articles were peer- reviewed by at least one independent reviewer.

Perhaps the accounts of the participants' current thoughts on their work in modular chemistry, and of the ensuing discussions, will entice additional scientists to enter the field and make it flourish. This would be the best possible reward to the contributors to this volume.
Reference books: C499

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