Molecular dynamics study of the solid state photoreactivity of 3- and 4-cyano-trans-cinnamic acids

Abstract

Molecular dynamics (MD) simulation studies show the importance of molecular motion and optimal π-π overlap of incipient reactive double bunds in the topochemical photodimerisation reactions of 3- and 4-cyanocinnamic acids. These simulations have been carried out in minicrystals consisting of 180 molecules and confirm earlier conclusions arising from packing calculations of static structures. A two-step diradical pathway for the climerisation is possible. A stepwise MD study has also been performed in which two molecules at the centres of the minicrystals have been dimerised and these calculations reveal the importance of thermal motion in these solid state photochemical reactions.