INFLUENCE OF PROTONATION ON THE REACTIONS OF TRIPLET-STATE SULFONATED CHLORO-ALUMINUM(III) PHTHALOCYANINE WITH DIOXYGEN

The kinetics of the reactions of sulfonated chloro-aluminium(III) phthalocyanine (AlSPC) in the excited state have been studied by laser flash photolysis. Two different protonated forms of this substance were identified in the triplet state 3-pi-pi*, AlSPC and AlSPCH+, differing in their lifetimes, tau almost-equal-to 290 and 90-mu-s, respectively, and rate of quenching by dioxygen [k(O2)f = (1.6 +/- 0.2) x 10(9) dm3 mol-1 s-1, k(O2)s = (6.6 +/- 0.7) x 10(7) dm3 mol-1 s-1, respectively]. It follows from the reaction kinetics that the establishment of equilibrium between the two forms AlSPC and AlSPCH+ in the 3-pi-pi* state is insufficiently mobile compared with the rate of quenching by dioxygen.