Properties of excited tetrakis(sulfonatophenyl)porphyrin in aqueous solutions. Photoredox reactions with quenchers

Abstract

Aqueous solutions of tetrakis(sulfonatophenyl)porphyrin (TPPS) have been investigated by using both steady-state and laser pulse photolysis. The spectrum and the lifetime of the triplet state of TPPS, T1, are reported. T1 is quenched by O2, p-benzoquinone (BQ), and nitrobenzene (NB) by second-order reactions. The rate constants were measured. The quenching of T1 by BQ and NB results in electron transfer products while O2 reacts by energy transfer. Possible reaction mechanisms, including the back-reactions, were investigated. The lowest excited singlet of TPPS, S1, was also studied. Its emission spectrum and lifetime were measured, and the effect of quenchers was studied. The results are disc..