Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, P R China.
J Phys Chem B. 2011 Feb 10;115(5):1175-87. doi: 10.1021/jp107752a. Epub 2011 Jan 5.
Infrared (IR) experiment, ab initio computations, and molecular dynamics (MD) simulations were used to examine the dynamical structures of ethylene glycol (EG) and 1,2-ethanedithiol (EDT) in carbon tetrachloride and deuterated chloroform. Using the O-H and S-H stretching modes as structural probes, EG and EDT were found to exhibit different conformational preferences, even though they share similar molecular formula. Results suggest that the gauche conformation of EG presents and is stabilized by the intramolecular hydrogen bond (IHB), while both the trans and gauche EDT are possible in the two solvents. Exchangeable IHB donor and acceptor pairs were predicted in the case of EG. Anharmonic vibrational frequencies, anharmonicities, and couplings of the O-H and S-H stretching modes were predicted and found to be structurally dependent. Linear IR and two-dimensional IR spectra containing these structural signatures were simulated and discussed. These results demonstrate that a combination of the methods used here is very useful in revealing structural dynamics of small molecules in condensed phases.
采用红外（IR）实验、从头算计算和分子动力学（MD）模拟研究了乙二醇（EG）和 1,2-乙二硫醇（EDT）在四氯化碳和氘代氯仿中的动态结构。利用 O-H 和 S-H 伸缩振动模式作为结构探针，发现 EG 和 EDT 尽管具有相似的分子式，但具有不同的构象偏好。结果表明，EG 的 gauche 构象通过分子内氢键（IHB）呈现并稳定，而在两种溶剂中，EDT 既可以是反式也可以是 gauche 构象。在 EG 的情况下，预测到了可交换的 IHB 供体和受体对。预测并发现 O-H 和 S-H 伸缩振动模式的非谐振动频率、非谐性和耦合与结构有关。模拟并讨论了包含这些结构特征的线性 IR 和二维 IR 光谱。这些结果表明，这里使用的方法组合非常有助于揭示凝聚相中小分子的结构动力学。
