气态二聚体[C_(1～6)mim]_2[BF_4]_2纳米微观结构的理论研究

A Theoretical Investigation of Nano-Microstructure for Gaseous Bipolymer [C_(1～6)mim]_2[BF_4]_2

在B3LYP/6-311+G(d,p)的水平上采用密度泛函理论研究了[C_nmim]+(n=1~6)与[BF_4]~ˉ形成二聚体[C_nmim]_2[BF_4]_2(n=1~6)的微观纳米结构。通过理论计算二聚体的相互作用能量发现,阴阳离子之间存在较强的氢键作用,且随着咪唑鎓烷基链的增加相互作用能也随之增加,另外,烷基侧链的长度会影响氢键强度。当咪唑鎓烷基侧链中C的个数大于4时,烷基尾部能够发生聚合,从而形成类胶束纳米结构。通过对自然布居分析、自然键轨道以及弱相互作用的分析和计算,同样证明了二聚体中存在较强的氢键作用,烷基侧链中碳的个数影响了离子液体的微观结构。

The interaction mechanisms and nanostructure between the cation and anion in 1-alkyl-3-methyl- imidazolium tetrafluroborate ionic liquids [ C nmim] 2 [ BF4 ] 2 were investigated at the B3LYP/6-311 ＋ G（ d, p） level. Through the theoretical calculation of the energy of the interaction of the dimer, it is found that there is a strong hydrogen bond between [ Cnmim] ＋ （n = 1 - 6） and [ BF4 ] -, and the interaction energy increases with the augmenting of imidazolium alkyl chain length. This consequence indicated that imidazolium alkyl chain length affects the strength of the hydrogen bonds. When the number of carbon on the imidazolium alkyl side chains is greater than four, The polymerization of alkyl tail is happen to form a kind of miecllar nanostructure. Through the analysis and calculation of NPA, NBO and weak interaction, it was also proved that there is a strong hydrogen bond in the dimer, and the number of carbon in the alkyl side chain affects the ionic liquid microstructure.