Special Mixing Behavior of Chelate-based Ionic Liquid with Methanol.

Compared to the general ionic liquids (ILs), a significant deviation of the binary mixtures of 1-decyl-3-methylimidazolium tri(hexafluoroacetylaceto)-copper(II) ([C10 mim][Cu(hfacac)3 ]) with methanol was found, indicating the way methanol interacts with ILs might be governed by the special structure of the chelating anion. IR results showed that the v (C2-H) of 1-decyl-3-methylimidazolium hexafluoroacetylacetonate ([C10 mim][hfacac]) blue-shifted more significantly than that of [C10 mim][Cu(hfacac)3 ], meanwhile the v (C=O) red-shifted in [C10 mim][Cu(hfacac)3 ], which is contrast with that in [C10 mim][hfacac]. Two-dimensional correlation analysis of the FTIR spectra indicated that the chelating cavity has little effect on the sequence of the ILs sites that interact with methanol. Combined with small angle X-ray scattering (SAXS) results, the picture of mixing processes in these two systems were proposed. Methanol interacts directly with the anion followed by the cation in [C10 mim][hfacac], while methanol preferentially enters the chelating cavity and enhances the packing effect in the [C10 mim][Cu(hfacac)3 ] system.