Aix Marseille University, CNRS, ICR, Marseille, France.
Aix-Marseille University, CNRS, PIIM, Marseille, France.
Phys Chem Chem Phys. 2022 May 25;24(20):12346-12353. doi: 10.1039/d2cp01056a.
Recent experimental work revealed that the lifetime of the S state of protonated 7-azaindole is about ten times longer than that of protonated 6-azaindole. We simulated the nonradiative decay pathways of these molecules using trajectory surface hopping dynamics after photoexcitation into S to elucidate the reason for this difference. Both isomers mainly follow a common ππ* relaxation pathway involving multiple state crossings while coming down from S to S in the subpicosecond time scale. However, the simulations reveal that the excited-state topographies are such that while the 6-isomer can easily access the region of nonadiabatic transitions, the internal conversion of the 7-isomer is delayed by a pre-Dewar bond formation with a boat conformation.
最近的实验工作表明，质子化 7-氮杂吲哚 S 态的寿命比质子化 6-氮杂吲哚的寿命长约 10 倍。我们在光激发到 S 态后使用轨迹表面跳跃动力学模拟了这些分子的非辐射衰减途径，以阐明这种差异的原因。两种异构体主要遵循一条共同的 ππ*弛豫途径，涉及多次态交叉，同时在亚皮秒时间尺度上从 S 到 S 下降。然而，模拟表明，激发态的形貌使得 6-异构体可以很容易地进入非绝热跃迁区域，而 7-异构体的内转换则由于与船型构象的预 Dewar 键形成而延迟。
