Guo Xugeng, Zhao Yuan, Cao Zexing
State Key Laboratory for Physical Chemistry of Solid Surfaces and Fujian Provincial Key Lab of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China.
Phys Chem Chem Phys. 2014 Aug 7;16(29):15381-8. doi: 10.1039/c4cp01928h. Epub 2014 Jun 19.
Extensive ab initio surface-hopping dynamics simulations have been used to explore the excited-state nonadiabatic decay of two biologically relevant hypoxanthine keto-N7H and keto-N9H tautomers in aqueous solution. QM/MM calculations and QM/MM-based MD simulations predict different hydrogen bonding networks around these nucleobase analogues, which influence their photodynamical properties remarkably. Furthermore, different solvent effects on the conical intersection formation of keto-N7H and keto-N9H were found in excited-state MD simulations, which also change the lifetimes of the excited states. In comparison with the gas-phase situation, the S1 → S0 nonradiative decay of keto-N7H is slightly faster, while this decay process of keto-N9H becomes much slower in water. The presence of π-electron hydrogen bonds in the solvated keto-N7H is considered to facilitate the S1 → S0 nonradiative decay process.
大量的从头算表面跳跃动力学模拟已被用于探索两种具有生物学相关性的次黄嘌呤酮-N7H和酮-N9H互变异构体在水溶液中的激发态非绝热衰变。量子力学/分子力学（QM/MM）计算和基于QM/MM的分子动力学（MD）模拟预测了这些核碱基类似物周围不同的氢键网络，这对它们的光动力学性质有显著影响。此外，在激发态MD模拟中发现了不同的溶剂对酮-N7H和酮-N9H锥形交叉形成的影响，这也改变了激发态的寿命。与气相情况相比，酮-N7H的S1→S0无辐射衰变略快，而酮-N9H的这种衰变过程在水中变得慢得多。溶剂化的酮-N7H中π电子氢键的存在被认为有助于S1→S0无辐射衰变过程。
