Mixing behavior of 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide and 1-Ethyl-3-methylimidazolium tetrafluoroborate binary ionic liquids mixtures

[Display omitted] Mixing two (or more) ionic liquids (IL) to form IL mixtures has become a new research hotspot for the design of ILs to achieve the desired properties. However, fundamental studies on interactions and mixing behaviors of the IL mixtures were reported less. In this work, the two ILs containing the same cation [EMIM]+ (1-ethyl-3-methylimidazolium) were selected to prepare ILs mixtures. The mixing behavior of the two IL mixtures were investigated by experimental method and quantum chemical calculations. The main conclusions were shown as follows: (1) DMSO form stronger hydrogen bonds with EMIMTFSI than EMIMBF4. (2) With addition of EMIMBF4, the hydrogen bonding interactions in EMIMTFSI−EMIMBF4 system were weakened, while the coulombic interactions were strengthened. (3) With the dilution, the C2−H has the smallest changes. A possible reason is the C2−Hs were still the main interaction site. (4) New formation complexes between EMIMBF4 and EMIMTFSI were assigned by excess infrared spectra.