紫外线激发胸腺嘧啶的态捕获新见解。
New Insights into the State Trapping of UV-Excited Thymine.
作者信息
Stojanović Ljiljana, Bai Shuming, Nagesh Jayashree, Izmaylov Artur F, Crespo-Otero Rachel, Lischka Hans, Barbatti Mario
机构信息
Aix Marseille Univ., CNRS, ICR, Marseille, France.
Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.
出版信息
Molecules. 2016 Nov 23;21(11):1603. doi: 10.3390/molecules21111603.
After UV excitation, gas phase thymine returns to a ground state in 5 to 7 ps, showing multiple time constants. There is no consensus on the assignment of these processes, with a dispute between models claiming that thymine is trapped either in the first (S₁) or in the second (S₂) excited states. In the present study, a nonadiabatic dynamics simulation of thymine is performed on the basis of ADC(2) surfaces, to understand the role of dynamic electron correlation on the deactivation pathways. The results show that trapping in S₂ is strongly reduced in comparison to previous simulations considering only non-dynamic electron correlation on CASSCF surfaces. The reason for the difference is traced back to the energetic cost for formation of a CO π bond in S₂.
紫外线激发后，气相胸腺嘧啶在5到7皮秒内回到基态，呈现出多个时间常数。对于这些过程的归属尚无共识，不同模型之间存在争议，一种模型认为胸腺嘧啶被困在第一激发态（S₁），另一种则认为被困在第二激发态（S₂）。在本研究中，基于ADC(2)表面对胸腺嘧啶进行了非绝热动力学模拟，以了解动态电子相关在失活途径中的作用。结果表明，与之前仅考虑CASSCF表面非动态电子相关的模拟相比，S₂中的俘获现象大幅减少。这种差异的原因可追溯到S₂中形成C-O π键的能量成本。
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