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SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS. XVII. BENZANTHRONE
Author(s) -
Dabestani Reza,
Sik Robert H.,
Motten Ann G.,
Chignell Colin F.
Publication year - 1992
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.1751-1097.1992.tb04275.x
Subject(s) - chemistry , rose bengal , singlet oxygen , photochemistry , electron paramagnetic resonance , quantum yield , ethanol , hydroxyl radical , yield (engineering) , oxygen , superoxide , anthracene , spin trapping , radical , nuclear chemistry , fluorescence , organic chemistry , physics , materials science , nuclear magnetic resonance , quantum mechanics , metallurgy , enzyme
— The photochemistry of benzanthrone (7H‐benz[de]‐anthracene‐7‐one) has been studied using electron paramagnetic resonance (EPR) in conjunction with the spin trapping technique and the direct detection of singlet molecular oxygen luminescence. Irradiation (Λ cx = 394 nm) of benzanthrone (BA) in aerated ethanol, dimethylsulfoxide or benzene resulted in the generation of superoxide (O − 2 ) which was trapped by 5,5‐dimethyl‐1‐pyrroline‐ N ‐oxide. The ethoxyl radical was also detected in ethanol. Photolysis of BA in deaerated basic ethanol led to the formation of BA anion radical, BA, which was detected directly by ESR. This radical anion decayed back to BA with a unimolecular rate constant of 1.5 × 10 ‐3 s ‐1 . The 1 O 2 quantum yields (Λ ex > 345 nm) for BA in ethanol, 90% ethanol and basic ethanol (0.1 N NaOH) were 0.89, 0.88 and 0.28 respectively relative to Rose Bengal. The lower yield of 1 O 2 in basic ethanol may be attributable to the reaction of oxygen with BA (which is generated in higher yield at alkaline pH) to give O − 2 . These findings suggest that on exposure to light BA can generate active oxygen species which may be responsible for the photocontact dermatitis caused by BA in industrial workers exposed to this chemical.