噻吩光解反应机理的理论研究

使用密度泛函理论(DFT)中的B3LYP方法, 采用6-31G**和6-31＋＋G**基组, 对噻吩的光解反应进行了理论研究. 对照实验结果, 我们研究了五个光解通道, 包括生成C₄H₄＋S, C₂H₂＋C₂H₂S和CS＋C₃H₄的三个闭壳层分子解离通道与生成HCS＋C₃H₃和HS＋C₄H₃的自由基解离通道. 各个可能的反应通道的产物碎片的具体形式得到了确认. 研究发现在基态生成C₂H₂＋C₂H₂S和在最低三态生成C₄H₄＋S的反应从能量上考虑最为有利, 而实验上观测到的主要产物C₂H₂＋C₂H₂S主要是在基态上产生的. 通过对比实验结果与计算结果, 我们认为噻吩光解反应机理与所用激发光波长有关.

Theoretical Investigations on the Photolysis of Thiophene

Density functional theory (B3LYP) along with 6-31G** and 6-31＋＋G** basis sets was employed to investigate the photodissociation reactions of thiophene. According to the experiment results, five photolysis channels have been examined, including three closed-shell molecular channels yielding C₄H₄＋S, C₂H₂＋C₂H₂S, and CS＋C₃H₄, and two radical channels yielding HCS＋C₃H₃ and HS＋C₄H₃. The most probable isomers of the product fragments were determined. It was found that the reaction yielding C₄H₄＋S was the most energetically favorable in the triplet state and c-C₄H₄S→C₂H₂＋C₂H₂S was preferential in the ground state. The calculation results show that C₂H₂＋C₂H₂S, which were found to be the major products, were formed mainly in the ground state. By comparison of the computational results with the experimental findings, it can be concluded that the photodissociation mechanism of thiophene is dependent on the wave length.