Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
Phys Chem Chem Phys. 2013 Nov 7;15(41):18055-64. doi: 10.1039/c3cp53356e.
In this work, the interactions between a representative imidazolium-based ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and acetonitrile (CH3CN) were investigated in detail using attenuated total reflection infrared spectroscopy (ATR-IR), hydrogen nuclear magnetic resonance ((1)H NMR), and density functional theory calculations. The main conclusions are: (1) a number of species in the [BMIM][BF4]-CH3CN mixtures were identified with the help of excess infrared spectroscopy and quantum chemical calculations. The dilution process of the ionic liquid by acetonitrile was found to be the transformation from ion clusters to ion pairs. (2) The solvent molecules cannot break apart the strong Coulombic interaction between BMIM and BF4 but can break apart the ion cluster into an ion pair within the concentration range investigated. The strength of hydrogen bonds between the C-Hs of BMIM and the N of acetonitrile is enhanced during the dilution process. (3) The methyl group of CH3CN locates above/below the imidazolium ring in the solution. These in-depth studies on the properties of the ionic liquid-acetonitrile mixed solvents may shed light on exploring their applications as reaction media in electrochemistry and chemical synthesis.
在这项工作中，使用衰减全反射红外光谱（ATR-IR）、氢核磁共振（（1）H NMR）和密度泛函理论计算详细研究了具有代表性的咪唑基离子液体 1-丁基-3-甲基咪唑四氟硼酸盐（[BMIM][BF4]）和乙腈（CH3CN）之间的相互作用。主要结论如下：（1）借助过量红外光谱和量子化学计算，鉴定出[BMIM][BF4]-CH3CN 混合物中的多种物质。发现离子液体被乙腈稀释的过程是从离子簇到离子对的转变。（2）溶剂分子不能打破BMIM和BF4之间的强库仑相互作用，但可以在研究的浓度范围内将离子簇分解成离子对。在稀释过程中，BMIM的 C-Hs 与乙腈的 N 之间氢键的强度增强。（3）CH3CN 的甲基基团位于溶液中咪唑环的上方/下方。对离子液体-乙腈混合溶剂性质的深入研究可能有助于探索它们在电化学和化学合成中作为反应介质的应用。
