Comparative kinetic study of the reactivity of molecules i n their excited singlet and triplet states in the cases of an electron abstraction and an intramolecular photocyclization reaction
1979; International Union of Pure and Applied Chemistry; Volume: 51; Issue: 2 Linguagem: Inglês
10.1351/pac197951020271
ISSN1365-3075
AutoresJacques Joussot–Dubien, Roland Bonneau, P. Fornier de Violet, Rafik Koussini, R. Lapouyade,
Tópico(s)Photochromic and Fluorescence Chemistry
ResumoTwo photochemical reactions are considered, illustrating quantitatively ~fferences in rate constants for chemical and physical deactivating processes from excited singlet and triplet states, in each case, for the identical photochemical reaction.Firstly we have determined the rate constants of electron abstraction, k , and quenching, k 6 , of oxonine singlet and triplet states by EDTA in aqueous solutiÖn.The rate ks for the singlet st~te, is found to be about ten times larger than kTe for the triplet stat~, whereas ksG is 103 to 104 faster than kTG.Secondly, in the case of the intramolecular photocyclization of 1-(orthodiphenyl) -1 phenyl ethylene in cyclohexane, a common intermediate X is found for the singlet and triplet pathways.The rate constant ksx is found to be 150 times faster than an apparent rate kTX whereas the non radlative (nr) rate constant ksnr is about 103 times faster than kTnr•
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