Photochemical studies of tetra-2,3-pyridinoporphyrazines

Tetra-2,3-pyridinoporphyrazines and the corresponding water-soluble N, N', N ", N " ' -tetramethyl-tetra-2,3-pyridinoporphyrazine complexes, containin g central metal atoms; M = Ce, Sn, Si and Zn, were synthesized and their ph otochemical properties were investigated. The reductive quenching of pyridi noporphyrazines excited states, enhanced relative to phthalocyanines, was c onsidered as the first photochemical step of dyes phototransformation in di methylformamide (DMF) and dimethylsulfoxide (DMSO) solutions under irradiat ion with visible light. Efficiency of singlet oxygen photosensitization dec reases significantly in the row phthalocyanines, unquaternized, quaternized tetra-2,3-pyridinoporphyrazine metallocomplexes. (C) 2001 Elsevier Science B.V. All rights reserved.