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PHOTOCHEMISTRY OF THE PHOTOTOXIC POLYACETYLENE PHENYLHEPTATRIYNE *
Author(s) -
Weir D.,
Scaiano J.C.,
Arnason J.T.,
Evans C.
Publication year - 1985
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.1751-1097.1985.tb08935.x
Subject(s) - photochemistry , singlet oxygen , chemistry , phototoxicity , quenching (fluorescence) , reaction rate constant , polyacetylene , singlet state , electron transfer , fluorescence , in vivo , oxidative phosphorylation , oxygen , excited state , kinetics , atomic physics , organic chemistry , physics , in vitro , biochemistry , microbiology and biotechnology , quantum mechanics , biology , polymer
— Investigation of the photochemistry of the phototoxic polyacetylene phenylheptatriyne, PHT, was undertaken to obtain further information on competing photo‐oxidative type II and non‐oxidative processes observed in vivo. Laser excitation (308 or 337 nm) led to the formation of a strong triplet signal with a lifetime of 28 μs in MeOH. The triplet was efficiently quenched by the triplet quencher 1,3‐octadiene ( k q ‐ 1.6 × 10 9 M ‐1 s ‐1 ). Quenching by O 2 occurred with a rate constant (1.7 × 10 9 M ‐1 s ‐1 ) comparable to the rate of electron transfer to methylviologen (1.4 × 10 9 M ‐1 s ‐1 ). The formation of singlet oxygen established earlier (type II reaction) in the former case and the semioxidized PHT radical in the latter case are consistent with the competing phototoxic processes observed in vivo .