纯水溶液中的氢键交换反应路径

利用分子动力学模拟方法对纯水溶液的氢键转化动力学性质进行了深入的微观探讨,溶液中非氢键构型为寿命较短(0.1～0.2 ps)的过渡态构型,我们发现氢键交换通过两种过渡构型完成,氢键角度扭曲激发后与氢键第一壳层水分子沿路径1交换,氢键径向拉伸激发后与氢键第二壳层水分子沿路径2交换,过渡态路径的选择具有温度依赖性.氢键转化需在旧氢键受体氢键过量和新氢键受体氢键不足,同时满足交换反应空间结构要求下才能完成.氢键交换反应对水分子平动和转动行为起着决定作用.

Transition Pathways of Hydrogen Bond Exchanging Reaction in Pure Water

Hydrogen bond(H-bond) kinetic of pure water was explored extensively by molecular dynamic simulations.The non-H-bond configuration should be considered as a transition state with a short lifetime scale of 0.1～0.2 ps.Two types of transition states were found,by which the H-bond exchanging reactions took place.Distortion of one H-bond stimulates the H-bond exchanging reaction with the water molecule in the first coordination shell by path 1.Elongation of one H-bond stimulates the H-bond exchanging reaction with the water molecule in the second coordination shell by path 2.The possibility of two paths in the process of H-bond exchange varies with the temperature.The H-bond exchanging events usually take place between the over-coordinated and under-coordinated H-bond acceptors,as well as a proper geometric configurations required.The H-bond exchanging reactions play a key role in the translational and rotational motions of water molecules.