Isomerization of cis,trans- and trans,trans-1,4-diphenylbuta-1,3-dienes by photoinduced electron transfer

Abstract

Photosensitization of cis,trans- or trans,trans-1,4-diphenylbuta-1,3-diene using a light-absorbing acceptor such as 9,10-dicyanoanthracene results in their geometric isomerization and leads to a photostationary mixture rich in trans,trans-1,4-diphenylbuta-1,3-diene (<94%) in benzene or acetonitrile. Spectroscopic studies in conjunction with quantum yield measurements suggest that a mechanism involving the triplet excited butadienes is feasible in benzene whereas a cation radical chain mechanism is operative in acetonitrile.