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  • Title: Substituted phthalocyanine-sensitized photochemical generation of superoxide anion radical.
    Author: Zhang XF, Xu HJ, Chen DW.
    Journal: J Photochem Photobiol B; 1994 Mar; 22(3):235-9. PubMed ID: 8014756.
    Abstract:
    The quantum yield of phthalocyanine-photosensitized generation of superoxide anion radical (O2-) was measured by the electron spin resonance (ESR) technique. From the redox potential data, it is concluded that O2- is formed by electron transfer from the singlet excited state (not triplet or ground state) of phthalocyanines (PCs) to oxygen. Since a much larger theoretical quantum yield of O2- generation (phi c) than experimental (phi m) was found, it is suggested that charge recombination processes between O2- and PCs+ occur more rapidly than O2- trapping by 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). The results indicate that the use of DMPO as a spin trap is not an ideal method for measurement of the quantity of O2- formed via photosensitization.
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