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THE EFFECT OF CHEMICAL STRUCTURE ON THE PHOTOSENSITIZING EFFICIENCIES OF PORPHYRINS
Author(s) -
Cauzzo Giulio,
Gennari Ciorgio,
Jori Giulio,
Spikes John D.
Publication year - 1977
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1977.tb07358.x
Subject(s) - photochemistry , chemistry , hematoporphyrin , flash photolysis , oxidizing agent , porphyrin , singlet oxygen , triplet state , fluorescence , excited state , singlet state , oxygen , photodissociation , photosensitizer , chelation , photodynamic therapy , reaction rate constant , inorganic chemistry , kinetics , molecule , organic chemistry , physics , quantum mechanics , nuclear physics
— A kinetic investigation was performed on the photooxidation of methionine sensitized by various porphyrins at different oxygen concentrations. The rate of photooxidation was found to be strongly dependent on the nature of the sensitizer. In the case of hematoporphyrin, chelation of Mg 2+ and Zn 2+ and especially of Cu 2+ and Fe 2+ caused a significant decrease of the photosensitizing efficiency. Fluorescence and/or flash photolysis studies showed that such a decrease is ascribed to an enhancement of the non‐radiative decay of the first excited singlet state as well as to a reduction of the triplet lifetime. The sensitizing efficiency is also dependent on the nature of the porphyrin side chains. A reaction mechanism involving 1 O 2 as the oxidizing agent is proposed.