Synlett 2002(2): 0201-0214
DOI: 10.1055/s-2002-19742
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© Georg Thieme Verlag Stuttgart · New York

The Chemistry of Intermolecular Bonding: Organic Crystals, their Structures and Transformations

Angelo Gavezzotti*
Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Università di Milano, via Venezian 21, 20133 Milano (Italy)
Fax: +39(02)58354454; e-Mail: angelo.gavezzotti@unimi.it;
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Publication History

Received 11 July 2001
Publication Date:
02 February 2007 (online)

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Abstract

The rationalization, prediction and control of structure and properties of organic condensed phases - crystals, liquids, mesophases, and solutions - is a frontier problem in chemistry, made difficult by the relative weakness and scarce directional selectivity of intermolecular bonding. A survey is given of the present status of theories of molecular recognition and of methods for the computer simulation of intermolecular interactions. The organic crystalline state is first considered: lattice energies; polymorphism and crystal chirality; the possibility of prediction of crystalline structure from molecular structure. Some account is then given of evolutionary modeling schemes, those involving a full dynamic simulation of the transformations of chemical systems: crystal melting; molecular aggregation from solutions into micelles and nuclei. As a perspective for years to come, it appears that molecular dynamics in the classical approximation with empirical potentials will be the method of choice in organic physical and theoretical chemistry.

3

Ferretti, V.; Gavezzotti, A.; Gilli, P. Chem. - Eur. J.,
in press.

7

For crystals, where molecules come very close to one another, the dipolar approximation to intermolecular potentials is unsatisfactory because the assumption that intermolecular distances be much larger than dipole dimensions is not valid. For similar reasons, dipole moments for very large molecules (e.g. proteins) are meaningless.

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See ref. [13] Thermochemical measurements are needed for comparisons, but thermochemistry does not really appeal to funding agencies. A research proposal entitled ‘Accurate Thermochemical Measurements on Organic Crystals’ admittedly appeals much less than something like ‘Crystal Engineering of Nano-chemical Systems for Supramolecular Devices and Materials’.

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A related technique is called Monte Carlo simulation: phase space is sampled by random changes in molecular positions and momenta, rather than by trajectories. MD has a more appealing kinetic flavor, though.

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See the references to the experimental work in the discussion in ref. [30]