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Kinetics of Photochemical Reactions of Thionine with Thiourea
Author(s) -
Uddin Fahim
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200004)2000:7<1345::aid-ejoc1345>3.0.co;2-0
Subject(s) - thionine , chemistry , thiourea , protonation , photochemistry , quantum yield , yield (engineering) , triplet state , methanol , acridine , inorganic chemistry , organic chemistry , molecule , fluorescence , electrochemistry , ion , physics , materials science , electrode , quantum mechanics , metallurgy
The photochemical reaction of thionine (Th) with an organic reductant such as thioureas was studied in absolute methanol at constant temperature 25±0.1°C. Spectrophotometric methods were adopted for the determination of the values of absorbances in the presence of extremely dissociated, undissociated and partially dissociated acridine in absolute methanol. The acidity of the reaction solution H 0 was controlled by using acetate buffer solutions. The effect of variables like concentration of thiourea, acidity and temperature on quantum yield (ϕ) was studied and the results were interpreted in terms of reaction mechanism. It was found that the quantum yield of the reactions of thionine with thiourea is controlled by two equilibria between (i) triplet state of thionine with proton and protonated triplet state of thionine, and (ii) protonated triplet state of thionine with reductant and associated complex (Th·H 2T ++ ·AH 2 ).