离子液体[bmim][PF_6]与乙腈混合体系中的激光光解研究

Laser Photolysis Study on Photochemical Reactions in Mixed Solutions of [bmim][PF_6] and Acetonitrile

以蒽醌(AQ)作为探针分子,利用激光光解技术研究了咪唑型离子液体1-丁基-3-甲基咪唑六氟化磷([bmim][PF6])与乙腈(MeCN)混合体系中的光化学反应行为。研究结果表明,离子液体[bmim][PF6]自身可与激发三线态的蒽醌分子(3AQ*)进行反应,且表观反应速率常数随着[bmim][PF6]/MeCN比例的不同呈现特殊规律性的变化。在离子液体的摩尔分数(xRTIL)为0.06处观察到一个明显的临界点。当xRTIL<0.06时,表观速率常数随xRTIL的增大而增大;而当xRTIL>0.06时,表观速率常数随xRTIL的增大而减小。文章给出了[bmim][PF6]/MeCN混合体系中激光诱导化学反应的动力学常数,并初步推测了其反应机理,进一步揭示了离子液体[bmim][PF6]的一些新的光化学特性。

Laser flash photolysis study was carried out for the first time in the binary mixture of room-temperature ionic liquid （RTIL） and traditional organic solvent. Photochemical properties of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] and its binary mixed solutions with MeCN were investigated by laser photolysis technique at an excitation wavelength of 355 nm, using anthraquinone （AQ） as a probe molecule. It was indicated that [bmim][PF6] itself participates in the reaction with 3 AQ.. Moreover, along with the change in the ratio of RTIL to organic solvent, the decay reaction rate constant of 3 AQ. changes regularly and a critical point was observed at xRTIL=0. 06. Before the critical point, the decay rate constant increases rapidly with increasing xRTIL ; however, it decreases obviously with increasing xRTIL after the critical point. The kinetic data are given, and the possible reaction mechanisms in mixed solutions are also speculated.