Ab initio and molecular mechanics study of conformational selectivity of chlorinated compounds adsorbed in the clathrate phase of syndiotactic polystyrene. The role of electrostatic host-guest interactions

A computational study of the conformational selectivity of some chlorinated compounds adsorbed in polymeric clathrates of syndiotactic polystyrene is presented. Ab initio investigation of the model complex benzene/CH3Cl gives information about the role of electrostatic interactions in determining th e favored molecular orientations,The changes of conformational equilibria o f some chlorinated compounds upon clathration have been rationalized by a m olecular mechanics approach. This shed light on the nature of the host-gues t interactions: although van der Waals interactions are most relevant for t he sorption process, the observed conformations are essentially associated with electrostatic interactions of the guest conformers with a substantiall y quadrupolar electrostatic field of the crystalline cavity.