UV direct photolysis of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in aqueous solution:: Kinetics and mechanism
UV direct photolysis of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in aqueous solution:: Kinetics and mechanism
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DOI：
10.1016/j.jphotochem.2007.12.030
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发表时间：
2008-06-25
影响因子：
4.3
通讯作者：
Yoon, Jeyong
中科院分区：
文献类型：
--
作者：
Lee, Changha;Yoon, Jeyong
研究了2，2‘-azino-bis(3-ethylbenzothiazoline-6-sulfonate)(ABTS)在2 5 4 nm单色紫外光照射下的直接光解反应。ABTS被紫外光直接光解，生成单电子氧化自由基ABTS(中心点+)，这是一种蓝绿色的持久自由基物种，具有很强的可见吸收带。ABTS(中心圆点+)的光化学产物强烈依赖于溶液的pH和溶解氧的存在。在pH为3时，溶解氧的存在提高了量子产率，而在pH为6.5时，它抑制了ABTS(中心点+)的产生。分光光度和荧光光谱数据表明，ABTS的光解可能是由于ABTS的单重态激发态和基态之间的单电子转移而发生的。在ABTS的UV/H_2O_2实验中所作的观察表明，ABTS的光解对溶液的pH和存在的溶解氧的依赖性与氢过氧基/超氧自由基(HO2中心点/O-2(中心点-))的作用有关，它似乎是通过ABTS的还原中间体与溶解氧的二次反应而形成的。所提出的光解反应得到了观察到的ABTS(中心点+)自由基量和ABTS分子分解量之间的化学计量比的支持。(C)2008爱思唯尔B.V.保留所有权利。
The direct photolysis of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in aqueous solution was investigated under monochromatic ultraviolet (UV) irradiation at 254 nm. ABTS was found to be directly photolyzed by UV irradiation to yield the one-electron oxidized radical, ABTS(center dot+), which is a blue-green colored persistent radical species that has strong visible absorption bands. The photochemical production of ABTS(center dot+) was strongly dependent on the solution pH and the presence of dissolved oxygen. The presence of dissolved oxygen increased the quantum yields at pH 3, whereas it inhibited the production of ABTS(center dot+) at pH 6.5. Spectrophotometric and spectrofluorometric data indicated that ABTS photolysis may occur as a result of the transfer of one-electron between the singlet excited state and the ground state of ABTS. Observations made during UV/H2O2 experiments with ABTS suggested that the dependence of the photoloysis of ABTS on the solution pH and the presence of dissolved oxygen is related to the role of the hydroperoxyl/superoxide radical (HO2 center dot/O-2(center dot-)), which appears to be formed via a secondary reaction of the reduced intermediate of ABTS with dissolved oxygen. The proposed photolytic reactions were supported by the observed stoichiometry between the amount of ABTS(center dot+) radicals produced and the amount of ABTS molecules decomposed. (c) 2008 Elsevier B.V. All rights reserved.