Intermolecular forces play a dominating role in the understanding of the molecular basis of life and in the development of new chemical technologies. Molecular recognition is at the heart of most methods in separation science and in medicinal chemistry, of new devices for information storage, transmission and amplification, for energy conversion, supramolecular catalysis and many new materials including sensors. Rational and thereby fast development of these fields relies to an essential degree on the quantitative characterization of the underlying non-covalent binding mechanisms and on advanced techniques to use intermolecular forces for new applications. These approaches should result in great contributions of chemistry towards a sustainable development of man's natural and artificial environment.
A number of articles in the present issue address the theoretical basis of non-covalent forces by primarily computational approaches (papers by Dougherty, Kaifer, Evanseck, Lipkowitz, Scheiner, Wipff et al.), drawing mostly on already classical problems of host-guest complexes. The quantification of intermolecular forces by empirical increments is exemplified or reviewed in papers by Abraham, Abboud, Raevsky et al. Based on experimental data from supramolecular complexes with a variety of different macrocycles Dougherty, Kaifer, Kikuchi, Murakami, Lhotak, Shinkai, Kano, Stoddart, Schneider and their coworkers characterize the often cooperative but mechanistically quite diverse interactions, which rule stabilities and selectivities as well as structures of such associations. Gutmann and Resch discuss the unique role of water in supramolecular assemblies. Anslyn et al. describe essential prerequisites for the characterization of hydrogen bonds. Intriguing possibilities to construct new molecular devices are outlined in contributions by Gokel, Stoddart and their collaborators.
The contributions assembled in this issue highlight the insights presently being made into important non-covalent binding mechanisms, the experimental possibilities to explore them with synthetic host-guest complexes and the development of new chemical applications and devices on this basis. The papers should help to make the scientific community, particularly chemists involved in physical organic approaches, aware of the great promises but also of the many unresolved problems in this field.