吡啶离子液体与水混合体系中蒽醌-2-磺酸钠的激光闪光光解机理

Laser Flash Photolysis Mechanism of Anthraquinone-2-Sodium Sulfonate in Pyridine Ionic Liquid/Water Mixed System

利用激光闪光光解技术研究了葸醌-2-磺酸钠（AQS）在吡啶离子液体Ⅳ．丁基吡啶四氟硼酸盐（[BPy][BF4]）与水（H20）混合体系中的光化学反应过程．实验结果表明，AQS的激发三重态（0AQS’）会与H20快速反应，不断增加[BPy][BF4]在混合体系中的体积比（KIL），瞬态吸收光谱发生了很大变化．510nm附近的瞬态吸收带变化最大，在0〈IL〈0．1时，吸光度会随着[BPy][BF4]的增加而增加；而在ⅥI．〉0．1时，吸光度则随着比例的增加而减小．然而380nm附近吸收带的吸光度却一直在增加．通过拟合近似地得到了瞬态物种B和0AQS^＊的表观动力学参数．另外还讨论了3AQS^＊与阳离子之间的夺氢反应，通过对350-420nm处光谱图的分析，推断出这一范围的瞬态吸收光谱是0AQS＋与AQSH^＊的叠加谱．在混合体系中，AQS^＊分别与H20和[BPy][BF4]的反应是一对竞争反应．还发现在高浓度的离子液体环境下，体系的整体反应速率会减弱．

The photochemical reaction process of anthraquinone-2-sodium sulfonate （AQS） in the mixture of water （H2O） and N-butylpyridinium tetrafluoroborate （[BPy] [BF4]） was studied using the laser flash photolysis technique. Experimental results show that the excited triplet of AQS （3AQS＊） could react rapidly with H2O and the transient absorption spectra greatly changed by increasing the volume fraction of the ionic liquid （VIL） in [BPy][BF4]/H2O mixtures. The absorbance at 510 nm increased gradually with increasing VIL when 0〈VIL〈0.1. By contrast, the absorbance decreased gradually when VIL〉0.1. Otherwise, the absorbance of the band near 380 nm steadily increased. The apparent kinetic parameters of transient species B and ^3AQS＊ are obtained approximately. 3AQS＊ abstracting hydrogen from [BPy]＋ was also explored. It was deduced that the 350-420 nm band was the superposition of the peaks of 3AQS＊ and AQSH＇. The two reactions of 3AQS＊ with [BPy][BF4] and H2O are a pair of competitive reactions. We also concluded that the entire reaction processes slow down in the case of high [BPy] [BF4] concentrations.