甲酰胺水溶液的分子动力学模拟

为了解重要的生化模型甲酰胺在水溶液中的微观结构, 采用全原子力场在全浓度范围内对甲酰胺溶液进行了分子动力学模拟, 得到了溶液的径向分布函数, 分析计算了溶质和溶剂分子间的相互作用, 对甲酰胺和水分子的氢键缔合情况进行了分析. 研究发现羰基侧的H原子与水分子能形成C—H…O弱相互作用. 在作者早期的研究中发现, 此相互作用对于阻碍甲酰胺的异构化具有重要意义, 特别是当甲酰胺在溶液中含量增大时, 此相互作用更加不能忽视. 全浓度溶液的模拟表明, 甲酰胺在稀浓度区可以促进水局部结构的增强, 随FM浓度增加, 由水的自身缔合转变为水与FM的交叉缔合, 在FM高浓度区, 两者的交叉缔合将逐渐被甲酰胺自身的线状缔合代替.

Molecular Dynamics Simulation for Formamide Aqueous Solution

In order to know more about the microcosmic structure of the important biochemical model molecule formamide (FM) in aqueous solution, the Optimized Potentials for Liquid Simulations-All Atom(OPLSAA) model were used in the molecular dynamics (MD) simulation for the aqueous solution of FMin the whole concentration range. The radial distribution functions of the solutions were obtained. The interaction between water molecule and FMmolecule was analyzed and calculated. It was found that there was a weak interaction (C—H…O) between the C—H beside the carbonyl of FM and water. The weak interaction could not be ignored, which was suggested to be significant in preventing the tautomerization of FM, especially when the concentration of FM increased in the aqueous solution of FM. By doing the calculation in the whole concentration range of the aqueous solution of FM, it was found that FM could strengthen the local structure of water in water-rich region. As the concentration increased, the association of water itself would be replaced by cross-association between water and FM gradually. In the FM-rich region, it was mainly the linear association of FMitself.