UV-resistant substances violacein have attracted much attention for the antioxidant properties such as inhabiting extreme environments. Herein, semi-empirical non-adiabatic dynamics simulations were employed to explore the S excited-state photochemical properties of violacein. After the system is excited to the Franck-Condon region, it relaxed to the S minimum. Subsequently, the single bond between 5-hydroxyindole and 2-pyrrolidone and the double bond between 2-pyrrolidone and oxindole were both twisted during deactivation to the conical intersection, and the 2-pyrrolidone ring was distorted with pyramidalization of a carbon atom. After passing through the conical intersection, the system returns to the ground state fastly. In non-adiabatic dynamics, it was found that 88.5 % of trajectories successfully returned to the ground state within 1 ps of the simulation time. In conclusion, we propose an excited-state deactivation mechanism for violacein system in vacuum, which will provide detailed mechanistic insights for similar light-shielding substances.

中文翻译：

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基于非绝热动力学模拟的VIO系统激发态失活机制

抗紫外线物质紫罗兰素因其在极端环境中的抗氧化特性而备受关注。在此，采用半经验非绝热动力学模拟来探索紫罗兰素的S激发态光化学性质。系统兴奋到 Franck-Condon 区域后，放松到 S 最小值。随后，5-羟基吲哚和2-吡咯烷酮之间的单键以及2-吡咯烷酮和羟吲哚之间的双键在失活过程中均扭曲成圆锥形交叉，并且2-吡咯烷酮环因碳原子的锥体化而扭曲。通过圆锥交点后，系统快速返回基态。在非绝热动力学中，我们发现 88.5% 的轨迹在模拟时间的 1 ps 内成功返回到基态。总之，我们提出了真空中紫色素系统的激发态失活机制，这将为类似的遮光物质提供详细的机理见解。