Xu Jing, Zhou Yu, Deng Geng, Ashraf Hamad, Yu Zhi-Wu
MOE Key Laboratory of Bioorganic Phosphorous, Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
School of Chemistry and Chemical Engineering, the Growing Base for State Key Laboratory, Qingdao University, Qingdao, 266071, P. R. China.
Chemphyschem. 2018 May 7;19(9):1030-1040. doi: 10.1002/cphc.201701302. Epub 2018 Feb 27.
Elucidation of the nature of noncovalent interactions between ionic liquids (ILs) and halogenated molecules is of particular importance for both fundamental research and drug development. Herein, the noncovalent interactions between 1-butyl-3-methyl-imidazolium acetate and three halobenzenes C F X (X=I, Br, H) were investigated. The iodine derivative shows the strongest interaction with the IL, followed by C F Br and C F H. As indicated by the positive/negative peaks and "multi/two-state" phenomena in the excess IR spectra, combined with DFT calculations, various interaction modes were differentiated. Three complexes, namely anion-C F I, anion-2 C F I, and ion-pair-C F I in the IL-C F I system were identified, whereas only ion-pair-C F Br/C F H complexes, together with self-associates, were found in the other two systems. A possible reason for the behavior of the IL-C F I system could be that the iodine-based halogen-bonding interactions in the system are strong enough to break interactions between the IL cations and anions. This might make C F I a good co-solvent to regulate the properties of acetate-based ILs.
阐明离子液体（ILs）与卤代分子之间非共价相互作用的本质，对于基础研究和药物开发都尤为重要。在此，研究了1-丁基-3-甲基咪唑醋酸盐与三种卤代苯CFX（X = I、Br、H）之间的非共价相互作用。碘衍生物与离子液体的相互作用最强，其次是CFBr和CFH。通过过量红外光谱中的正/负峰和“多/双态”现象，并结合密度泛函理论计算，区分了各种相互作用模式。在IL-CFI体系中鉴定出三种配合物，即阴离子-CFI、阴离子-2CFI和离子对-CFI，而在其他两个体系中仅发现离子对-CFBr/CFH配合物以及自缔合体。IL-CFI体系表现出这种行为的一个可能原因可能是该体系中基于碘的卤键相互作用足够强，足以打破离子液体阳离子和阴离子之间的相互作用。这可能使CFI成为调节醋酸盐基离子液体性质的良好共溶剂。
