INCLUSION COMPOUNDS: RELATING STRUCTURE TO THERMAL STABILITY. L. R. Nassimbeni, Chemistry Department, University of Cape Town, Rondebosch 7700, South Africa

Research on inclusion compounds has largely concentrated on the synthesis of novel host compounds, aimed at selective enclathration of targeted guest molecules. We have directed our program to the understanding of the intermolecular forces which are responsible for the process of molecular recognition between host and guest, in order to explain the physical properties of inclusion compounds.

We have synthesised a variety of host-guest complexes comprising bulky hosts containing the hydroxyl moiety, have elucidated their crystal structures and measured their thermodynamic stabilities with a variety of analytical techniques. The kinetics of enclathration of a gaseous guest by a solid host has been studied using a novel magnetic suspension balance, while the kinetics of thermal decomposition of labile clathrates has allowed us to elucidate the mechanism of the desolvation reactions. Competition experiments between close isomers of a guest have been carried out both in solution and with the host in suspension, and we have extended this principle to solid-solid systems.

The results of both the dynamic and equilibrium experiments are rationalised in terms of the molecular structures and the crystal packings of the host-guest compounds concerned.