Department of Chemistry, MeChem Group, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, National Demonstration Center for Experimental Chemistry & Chemical Engineering Education, School of Science, Tianjin University, Tianjin 300354, China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2023 Oct 5;298:122759. doi: 10.1016/j.saa.2023.122759. Epub 2023 Apr 18.
In this work, we investigated the potential UV protection mechanism of the natural compounds hydroxy resveratrol and pterostilbene by combining theoretical calculations and femtosecond transient absorption spectra (FTAS). The UV absorption spectra showed that the two compounds exhibited strong absorption properties and high photostability. We found two molecules will reach the S state or an even higher excited state after UV exposure and molecules in S will cross a lower energy barrier to reach the conical intersection. The adiabatic trans-cis isomerization process happened and finally return to the ground. Meanwhile, FTAS clarified the time scale of trans-cis isomerization of two molecules was ∼ 10 ps, which also met the requirement of fast energy relaxation. This work also provides theoretical guidance for developing new sunscreen molecules from natural stilbene.
在这项工作中，我们通过结合理论计算和飞秒瞬态吸收光谱（FTAS）研究了天然化合物羟基白藜芦醇和紫檀芪的潜在紫外保护机制。紫外吸收光谱表明，这两种化合物表现出较强的吸收特性和高光稳定性。我们发现，两种分子在紫外照射后将分别达到 S 态或更高的激发态，且 S 态的分子将跨越较低的能量势垒到达锥形交叉点。然后发生非绝热的顺反异构化过程，最终回到基态。同时，FTAS 还阐明了两个分子的顺反异构化时间尺度约为 10 ps，这也符合快速能量弛豫的要求。这项工作也为从天然芪类化合物开发新型防晒分子提供了理论指导。
