Xie Bin-Bin, Liu Bo-Long, Tang Xiu-Fang, Tang Diandong, Shen Lin, Fang Wei-Hai
Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
Phys Chem Chem Phys. 2021 Apr 28;23(16):9867-9877. doi: 10.1039/d1cp00281c.
In the present work, the quantum trajectory mean-field approach, which is able to overcome the overcoherence problem, was generalized to simulate internal conversion and intersystem crossing processes simultaneously. The photoinduced ring-opening and subsequent rearrangement reactions of isolated 2(5H)-thiophenone were studied based on geometry optimizations on critical structures and nonadiabatic dynamics simulations using this method. Upon 267 nm irradiation, the molecule is initially populated in the 1ππ* state. After a sudden rupture of one C-S bond within 100 fs in this state, the lowest two singlet excited states and the lowest two triplet excited states become quasi-degenerated, and then the intersystem crossing processes between singlet and triplet states accompanied by rearrangement reactions can be observed several times. Compared with our previous nonadiabatic simulations in the absence of intersystem crossing (ChemPhotoChem, 2019, 3, 897-906), some new nonadiabatic relaxation pathways involving triplet states and different ring-opening products were identified. The present work provides new mechanistic insights into the photoinduced ring-opening of thio-substituted heterocyclic molecules and reveals the importance of nonadiabatic dynamics simulation that is able to deal with multiple electronic states with different spin multiplicities.
在本工作中，能够克服过相干问题的量子轨迹平均场方法被推广以同时模拟内转换和系间窜越过程。基于关键结构的几何优化以及使用该方法的非绝热动力学模拟，研究了孤立的2(5H)-噻吩酮的光致开环及随后的重排反应。在267 nm光照下，分子最初处于1ππ*态。在此状态下，一个C-S键在100 fs内突然断裂后，最低的两个单重激发态和最低的两个三重激发态变得准简并，随后可以多次观察到伴随着重排反应的单重态和三重态之间的系间窜越过程。与我们之前在没有系间窜越情况下的非绝热模拟（《化学光化学》，2019年，第3卷，897 - 906页）相比，确定了一些涉及三重态和不同开环产物的新的非绝热弛豫途径。本工作为硫代取代杂环分子的光致开环提供了新的机理见解，并揭示了能够处理具有不同自旋多重性的多个电子态的非绝热动力学模拟的重要性。
