Tang Zhe, Qi Yutai, Wang Yi, Zhou Panwang, Tian Jing, Fei Xu
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics , Chinese Academy of Science , Dalian 116023 , China.
J Phys Chem B. 2018 Apr 12;122(14):3988-3995. doi: 10.1021/acs.jpcb.7b10207. Epub 2018 Mar 29.
This paper identified a new excited-state proton transfer (ESPT) mechanism for 2,6-diazaindoles (2,6-DAI) in aqueous (HO) solution based on time-dependent density functional theory. The calculated results show that the excited-state three proton transfer reaction cannot occur because the 2,6-DAI with two water molecules do not form hydrogen bond wires; this finding was different from those reported in previous experiments (Chung et al. J. Am. Chem. Soc. 2017, 139, 6396-6402). 2,6-DAI with three water molecules form 2,6-DAI·(HO) clusters, whereas 2,6-DAI with four water molecules form 2,6-DAI·(HO) cluster. These clusters participate in the ESPT reaction. To determine the ESPT mechanism of 2,6-DAI·(HO) and 2,6-DAI·(HO) clusters, we constructed the potential energy curves of S and S states. The results confirmed the simultaneous presence of both 2,6-DAI·(HO) and 2,6-DAI·(HO) clusters and only one proton transfer pathway. By calculating the transition states of 2,6-DAI·(HO) and 2,6-DAI·(HO) clusters, we found that the ESPT reaction is a consistent mechanism. Our work investigated the number of water molecules involved in the ESPT and paved the way to further study the intermolecular hydrogen bonding interactions in the biological field.
本文基于含时密度泛函理论，确定了2,6 - 二氮杂吲哚（2,6 - DAI）在水（H₂O）溶液中的一种新的激发态质子转移（ESPT）机制。计算结果表明，激发态三质子转移反应不会发生，因为带有两个水分子的2,6 - DAI不会形成氢键链；这一发现与先前实验报道的结果不同（Chung等人，《美国化学会志》，2017年，139卷，6396 - 6402页）。带有三个水分子的2,6 - DAI形成2,6 - DAI·(H₂O)₃簇，而带有四个水分子的2,6 - DAI形成2,6 - DAI·(H₂O)₄簇。这些簇参与ESPT反应。为了确定2,6 - DAI·(H₂O)₃和2,6 - DAI·(H₂O)₄簇的ESPT机制，我们构建了S₀和S₁态的势能曲线。结果证实了2,6 - DAI·(H₂O)₃和2,6 - DAI·(H₂O)₄簇同时存在且只有一条质子转移途径。通过计算2,6 - DAI·(H₂O)₃和2,6 - DAI·(H₂O)₄簇的过渡态，我们发现ESPT反应是一种一致的机制。我们的工作研究了参与ESPT的水分子数量，为进一步研究生物领域中的分子间氢键相互作用铺平了道路。
