Catalysis of triplet state cis-trans isomerizations making a quantum chain process more efficient

Photocatalysis of cis-trans isomerizations is treated in this paper. Two systems, 8-( 3,5-ditert-butylstyryl) fluoranthene/camphorquinone/acridine and 1,6-bisstyryl-1,3,5-cycloheptatriene/C60 were studied. rn the first system Z-8-(3,5-ditert-butylstyryl)fluoranthene is photoisomerized with acridine as the catalyst and camphorquinone as triplet sensitizer, and in the second Z,E-1,6-bisstyryl-1,3,5-cycloheptatriene is isomerized with C60 as both catalyst and triplet sensitizer. The quantum efficiencies were found to increase 5.5 times in the first case and to be doubled in the second. The effect of concentration of both the catalyst and the reactant were investigated. The results are explained as an increased efficiency of a quantum chain process, and a theoretical model is used to evaluate the results. (C) 1998 Elsevier Science S.A.