摘要
报道了在室温条件下利用pcff力场和Rattlebond法对 β 环糊精 (β CD)和对 甲基苯酚形成的 1∶1CD包结物溶解在 4 2 7个水分子中形成的纳米水滴在 2 0 0 ps时间间隔内进行约束动力学模拟的结果 ,并与真空下的CD包结物进行了比较 .结果表明 ,在模拟时间内 ,CD包结物在水滴中和真空中是稳定的 .通过对径向分布函数 (rdf)的计算发现 ,在模拟时间内 ,没有一个水分子进入环糊精包结物腔体内 ,用约束动力学模拟方法证实了CD腔体确实具有疏水作用 .模拟研究还发现 ,水滴中环糊精的亲水外侧确实存在明显的由氢键引起的水化作用 ,与环糊精的性质相吻合 ;对 甲基苯酚的酚羟基在水滴中与水分子间存在明显的氢键作用 ,而在真空中则与 β CD的宽口处的O3间存在明显的氢键作用 ,这使得客体在水滴中插入CD中的深度要浅于在真空中的情形 .实验模拟结果说明 ,可以利用约束动力学的方法来研究水溶液体系的动力学行为 .
Two systems of 1∶1 inclusion of host β-cyclodextrin and guest p-cresol in nano-drip including 427 H_2O molecules and in vacuum have been studied by the constrain molecular dynamics simulation technique with pcff force field and Rattle bond algorithm. The analysis on the dynamic structure of inclusion and radial distribution function of several kinds of oxygen atoms shows that the CD inclusion was stable during the simulation time period in two systems and none of water molecule was found to move into the CD cavity in the drip within 200 ps which conformed the hydrophobic property of CD cavity. In the drip, an obvious hydration caused by H-bonding existing in the CD hydrophilic outsides was observed, and it agreed well with the CD properties. The obvious H-bonding interactions existing between phenyl hydroxyl and water molecules in the drip and between phenyl hydroxyl and CD cavity in vacuum made the guest molecule insert into the CD cavity shallower in drip case than in vacuum case. It was concluded that the constrain molecular dynamics simulation technique can be used to investigate the dynamic behavior of CD aqueous solution.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina (2 99730 36 ) .
