特殊缔合体系TFE水溶液分子动力学模拟

三氟乙醇(TFE)水溶液是一类特殊的缔合体系. 采用分子动力学模拟方法结合核磁共振化学位移研究了TFE水溶液体系全浓度范围的氢键网络, 并对动力学模拟结果和核磁共振化学位移进行了比较. 从径向分布函数(RDF)发现, TFE水溶液中存在着强氢键, 而体系中的C—H…O弱相互作用较为明显, 也不能忽略. 氢键网络分析发现TFE 水溶液体系的氢键大致分为以下三个区域: 在水富集区域, 水分子倾向于自身缔合形成稳定的簇结构, 随着TFE 浓度的增加, 水的有序结构受到破坏, 水分子和TFE分子发生交叉缔合作用形成氢键; 在TFE富集区域, 水分子较少, TFE分子自身通过氢键形成多缔体结构. 此外, 分子动力学统计的平均氢键数的变化和文献报导的核磁共振化学位移变化趋势相同, 实验和理论的结果吻合较好.

Molecular Dynamics Simulations on the Special System of TFE Aqueous Solution

2,2,2-trifluoroethanol (TFE) aqueous solution is a special associate system. Molecular dynamics (MD) simulations combined with the chemical shifts in NMR were used to investigate the hydrogen-bond network in TFE-water system. The strong hydrogen bonds and weak C—H…O contacts were found existing in the TFE-water mixtures from the information of radial distribution function (RDF). And the TFE-water mixtures could be divided into three different regions from the analysis of the hydrogen-bonding network. In the water rich region, water molecules prefer to form the hydrogen bonds with themselves and establish the stable clusters. With the concentration of TFE increasing, the stable structure of water molecules was broken down. In the TFE rich region, the self-associated clusters of TFE were dominant. In addition, the chemical shifts were adopted to study the interactions in the mixtures. The varieties of the average hydrogen bond numbers fromMD simulations and the chemical shifts in NMR showed good agreement.