Photoinduced electron transfer reactions of 1,4-diphenyl-1,3-butadiyne

Abstract

Irradiation of 1,4-diphenyl-1,3-butadiyne (DPB) in the presence of 9,10-dicyanoanthracene (DCA) yields new methanol photoadducts in addition to normal photoadducts formed in the absence of DCA. Laser flash photolysis studies indicate that new methanol photoadducts are formed through a photoinduced electron transfer mechanism involving DPB radical cation and DCA radical anion. Substitution of one of the two phenyl rings with a p-methoxy group inhibits the formation of radical ion pairs and does not give any methanol photoadduct formed through radical ion pairs, while p-nitro group enhances the formation of radical ion pairs and gives photoadducts solely generated from the radical ion pairs.