College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China.
Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Phys Chem Chem Phys. 2022 Sep 14;24(35):21358-21366. doi: 10.1039/d2cp03283j.
The excited-state proton transfer processes and the formation mechanism of quinone methide of (1-naphthyl)phenol were investigated by combining static electronic structure calculations and non-adiabatic dynamics simulations in vacuum. The results indicated the existence of two minimum energy structures (S0-ENOL-1 and S0-ENOL-2) in the ground and excited states, which correspond to two ESIPT pathways. Upon excitation of S0-ENOL-1 to the bright S state, the system relaxes to the S minimum quickly in the enol region, for which two decay pathways have been described. The first is a barrierless ESIPT-1 process that generates keto species. Afterwards, the system encounters a keto conical intersection, which funnels the system to the ground state. The generated keto species, in the S state, either regenerated the starting material ground-state proton transfer or yielded the keto product at the end of the simulations. In the other pathway, the system de-excites from the S state to the S state one enol-type conical intersection. The dynamics simulations showed that 58.8% of trajectories experience keto-type conical intersection and the rest undergo enol-type conical intersection. Besides the ESIPT-1 process, a new-type ESIPT (ESIPT-2), which was not observed experimentally, was found with the irradiation of S0-ENOL-2. The ESIPT-2 process occurs after overcoming a small barrier (0.9 kcal mol) and yields a distinct quinone methide. Our simulation results also showed that the S lifetime of S0-ENOL-1 (S0-ENOL-2) would be 437 (617) fs in the gas phase. These results provide detailed and important mechanistic insights into the systems in which ESPT to carbon atoms occurs.
在真空条件下，通过结合静态电子结构计算和非绝热动力学模拟，研究了（1-萘基）苯酚的激发态质子转移过程和醌亚甲醚的形成机制。结果表明，在基态和激发态中存在两个最低能量结构（S0-ENOL-1 和 S0-ENOL-2），它们对应于两种 ESIPT 途径。当 S0-ENOL-1 被激发到明亮的 S 态时，系统在烯醇区域迅速松弛到 S 态的最小值，其中已经描述了两种衰减途径。第一种是无势垒的 ESIPT-1 过程，生成酮物种。之后，系统遇到一个酮锥形交叉点，将系统引导到基态。在 S 态下生成的酮物种，要么在模拟结束时重新生成起始材料 基态质子转移，要么生成酮产物。在另一条途径中，系统从 S 态退激发到 S 态 一个烯醇型锥形交叉点。动力学模拟表明，58.8%的轨迹经历酮型锥形交叉点，其余的经历烯醇型锥形交叉点。除了 ESIPT-1 过程外，还发现了一种新型的 ESIPT（ESIPT-2），这种过程在实验中没有观察到，它是由 S0-ENOL-2 的辐照引起的。ESIPT-2 过程发生在克服一个小势垒（0.9 kcal mol）之后，并产生一个明显的醌亚甲醚。我们的模拟结果还表明，S0-ENOL-1（S0-ENOL-2）的 S 寿命将在气相中分别为 437（617）fs。这些结果为发生碳原子 ESPT 的体系提供了详细而重要的机制见解。
