A theoretical and experimental study of cyano- and alkoxy-substituted phenylenevinylene model compounds

We present a theoretical and experimental investigation of methoxy- and cya no-substituted p-phenylenevinylene model compounds. The compound containing both the alkoxy and cyano substitution exhibits a drop in the quantum yiel d relative to the singly-substituted alkoxy or alkyl compounds. In addition the emission spectrum loses structure and shifts to the red. Model calcula tions are performed on the chromophore and ab-initio CIS calculations show that the first excited state HOMO to LUMO transition is delocalised in meth oxy-substituted compounds and localised on methoxy- and cyano-substituted c ompounds. (C) 2000 Elsevier Science S.A. All rights reserved.