MEDIUM EFFECTS ON THE PHOTOCHEMICAL-REACTION BETWEEN PYRENE AND INDOLE - A LASER FLASH-PHOTOLYSIS STUDY

A laser flash photolysis study of the photoinduced electron-transfer reaction between pyrene and indole is reported. The pyrene radical anion and the hydropyrenil radical were confirmed as reaction intermediates from their transient absorption spectra. The photobleaching of pyrene was observed in the presence of indole but not in the presence of 1-methylindole. The quantum yields of the reaction and of the transient species are highly dependent on the solvent. The reaction was also carried out in the presence of tetrabutylammonium perchlorate, and an inhibitory effect by the salt was observed. At the same time, the quantum yield of the free ions increased. The results were interpreted by a mechanism that involves a proton transfer following the initial electron transfer. The effect of micelles on the reaction was also investigated.