Influence of protonation on the reactions of triplet-state sulfonated chloro-aluminium(<scp>III</scp>) phthalocyanine with dioxygen

Abstract

The kinetics of the reactions of sulfonated chloro-aluminium(III) phthalocyanine (AISPC) in the excited state have been studied by laser flash photolysis. Two different protonated forms of this substance were identified in the triplet state 3ππ*, AISPC and AISPCH+, differing in their lifetimes, τ≈ 290 and 90 µs, respectively, and rate of quenching by dioxygen [ko2f=(1.6 ± 0.2)× 109 dm3 mol–1 s–1, ko2s=(6.6 ± 0.7)× 107 dm3 mol–1 s–1, respectively]. It follows from the reaction kinetics that the establishment of equilibrium between the two forms AISPC and AISPCH+ in the 3ππ* state is insufficiently mobile compared with the rate of quenching by dioxygen.