COMPARISON OF PHOTOINDUCED ELECTRON TRANSFER REACTIONS OF AROMATIC CARBONYL VS. CYANO COMPOUNDS WITH ELECTRON DONORS IN CONDENSED PHASE: THE IMPORTANCE OF THE SPIN STATE OF THE GEMINATE ION PAIR FOR OBTAINING HIGH ION YIELDS.

Article abstract of DOI:10.1016/S0040-4020(01)86228-1

Photoinduced electron transfer reactions in acetonitrile with benzophenone, anthraquinone, 9-cyanoanthracene and 9,10-dicyanoanthracene as electron acceptors, and with 1,4-diazabicyclo<2,2,2>octane and N,N-dimethylaniline as electron donors have been studied with ns-laser flash photolysis and fluorescence quenching measurements.For these systems the resulting free ion yield depends on the spin state of the geminate ion pair: its separation is very efficient if formed in a triplet state (carbonyl compounds/donors), while it is very inefficient if formed in a singlet state (cyanoantracenes/donors).In the triplet systems, geminate back electron transfer is limited by the rate of spin flip.