The Crystal Packing of Organic Molecules: Challenge and Fascination Below 1000 Da

Abstract

Studies and insights on the crystal packing of organic molecules are reviewed, beginning with the first investigations of intermolecular effects in the sixties, the early database studies in the seventies, and proceeding to the structure correlation principle and the Kitaigorodski approach to intermolecular analysis. Present-day instrumentation allows a new attitude towards organic small-molecule X-ray crystallography: connections with solid-state thermodynamics and kinetics are envisaged. Recent Cambridge Database studies, new intermolecular “bonds”, optimizations of crystal potentials, and crystal structure generation and prediction software, are critically analyzed, together with crystal engineering which, as it appears now, is a branch of synthetic organic chemistry. The future of theoretical studies of crystals, and more generally of all physical chemistry, is molecular dynamics; its use in simulating and describing solids, liquids and solutions is outlined, with special attention to crystal nucleation and growth. In summary, a broader definition of the crystallographically oriented scientist is sought, and it is argued that crystallography should not be surrendered to macromolecular chemistry without fighting.