Substitution effects on the photoisomerisation of vinyl cinnamates

In a recent article, the reaction path between different structures and the localisation of the transition state were carried out in order to study th e particular structural changes and photosensitivity of the poly (vinyl cin namate) (PVCN). In the present work quantum calculations are performed in o rder to determine the energy required for configurational changes according to a similar scheme for a variety of PVCN substituted in different positio ns of the aromatic ring. The calculated reaction path between different str uctures and the localisation of the transition state exhibit a high photose nsitivity in the visible or the near-infrared spectrum for this ester and r elated compounds. Major effects are characterised for halogenated monomers in different positions of the aromatic group, with a particular behaviour o f the brominated monomer. Selective photoisomerisation processes can occur according to the type and site position of the substituant. (C) 1999 Elsevi er Science B.V. All rights reserved.