Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Photochemical Primary Processes of Xanthene Dyes. I. Investigations of the Primary Processes of Selenopyronine by Flash ExcitationThe triplet-state of selenopyronine absorbs light in the whole investigated spectral range (λmax = 400 nm, 480 nm, 690 nm). As results of the bimolecular triplet decay a half-reduced (λmax = 430 nm) and a half-oxidized (λmax = 475 nm) form of the dye are observed. p-Benzoquinone quenches the triplet-state (k7 = 1,5 · 109 l/mol s) and the results are the half-oxidized form and the p-benzosemiquinone ion. For these two products different decay processes exist. The reducing agents DABCO, EDTA and Hydroquinone also quench the triplet state (k10 = 1,2 · 106 l/mol s, k11 = 1,0 · 106 l/mol s, k12 = 1,0 · 109 l/mol s) and as result the half-reduced form is observed. Measurements with thiopyronine give analogous results, which are in good agreement with investigations published in the literature.
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