Substituted phthalocyanine-sensitized photochemical generation of superoxide anion radical.
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.
Institute of Photographic Chemistry, Academia Sinica, Beijing, China.
X F
XF
Zhang
H J
HJ
Xu
D W
DW
Chen
D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004579:Electron Transport; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D007700:Kinetics; D015394:Molecular Structure; D011789:Quantum Theory; D011838:Radiation-Sensitizing Agents / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D013113:Spin Labels; D013481:Superoxides / Q000032:analysis*; D013816:Thermodynamics
D003497:Cyclic N-Oxides; D007211:Indoles; D054833:Isoindoles; D011838:Radiation-Sensitizing Agents; D013113:Spin Labels; D013481:Superoxides; C017245:5,5-dimethyl-1-pyrroline-1-oxide; C013647:phthalocyanine