N-丁基吡啶四氟硼酸盐/水二元体系的分子动力学模拟研究

Molecular dynamics simulation study of N-butylpyridinium tetrafluoroborate/water binary system

利用分子动力学模拟方法研究了离子液体N-丁基吡啶四氟硼酸盐([BPy]BF4)与Tip4p模型水分子的二元体系的微观结构.比较了各组分间的径向分布函数,结果表明随着离子液体比例的增加,水与阴离子、水与阳离子头部吡啶环、阳离子头部与阴离子上相关原子间的径向分布函数峰值都呈现递增的趋势,而阳离子上丁基链末端碳原子间的径向分布函数没有明显变化;空间分布函数则直观地反映出阴离子主要分布在阳离子的吡啶环周围,水分子在阴离子周围近似呈均等分布,且几率随离子液体比例增大而增加;另外还探讨了不同离子液体比例下的二元体系中氢键的数目和寿命,结果均呈现一定规律的变化.

Molecular dynamics simulation method was used to study the microscopic structure of the binary system of the ionic liquid N-butylpyridinium tetrafluoroborate([BPy]BF_(4))with water.Radial distribution functions(RDFs)for different components were compared.The results showed that,with the increase of the proportion of[BPy]BF_(4),the peaks of RDFs for two certain atoms between water molecule and anion,water molecule and pyridine ring in cation,anion and pyridine ring in cation presented an increasing trend,but that of the terminal carbon of the butyl side-chain in[BPy]BF_(4)had no obvious change.Spatial distribution functions intuitively reflected that the anions were mainly distributed around the pyridine ring of the cation,water molecules were almost equally distributed around anion,and the probability increased with the increase of the proportion of ionic liquids.Numbers and lifetimes of hydrogen bonding between water molecules were also calculated under different proportions of ionic liquid,and the results showed some regular changes.