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ANTHRALIN‐DERIVED TRANSIENTS—II. FORMATION OF THE RADICAL BY SPONTANEOUS FRAGMENTATION OF BOTH SINGLET AND TRIPLET STATES OF THE 10,10′‐DEHYDRODIMER: RADICAL PAIR MULTIPLICITY EFFECTS
Author(s) -
Bruce J. M.,
Dodd N. J. F.,
Gorman A. A.,
Hamblett I.,
Kerr C. W.,
Lambert C.,
McNeeney S. P.
Publication year - 1990
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.1751-1097.1990.tb04190.x
Subject(s) - chemistry , photochemistry , radical , singlet state , singlet oxygen , fragmentation (computing) , tautomer , radiolysis , diradical , dimer , excited state , stereochemistry , oxygen , atomic physics , physics , organic chemistry , computer science , operating system
— The singlet and triplet states of the anthralin (1,8‐dihydroxy‐9‐anthrone) dehydrodimer have been produced selectively in benzene via pulsed laser excitation and pulse radiolysis respectively. The lifetime of S, is 30 ps, that of T, short but unspecified. Both states fragment spontaneously to yield a pair of anthralin radicals. The singlet radical pair predominantly undergoes geminate recombination within the solvent cage. In contrast, the corresponding triplet radical pair undergoes essentially exclusive cage escape to give the anthralin free radical (δ. max 370, 490 and 720 nm) which recombines under normal diffusive conditions. Both recombination processes lead, at least in part, to one or more species which have been assigned as tautomeric forms of the original dimer. The anthralin free radical in benzene is insensitive to the vitamin E model 6‐hydroxy‐2,2,5,7,8‐pentamethylchroman and reacts only slowly with oxygen.