Fig. 3: Molecular characterization of MESHPIE.

ATR-FTIR characterization of [BMIM]⁺[TFSI]^-, MESHE, and MESHPIE to verify the ion-dipole interaction. a The spectral range of 1400–1280 cm⁻¹ and b 1120–920 cm⁻¹ corresponds to the stretching of TFSI^– vibrational bands in MESHPIE owing to the weakened Coulomb forces generated by the ion-dipole interaction effect on the cations. c Schematic representation of ion–dipole interaction between C–F groups and the [BMIM]⁺ cation, and the Coulomb force between the ion pairs. ATR-FTIR spectra in the spectral regions of d 1400–1000 cm⁻¹ (pertaining to TFSI⁻ stretching) and e 3210-3060 cm⁻¹ (pertaining to BMIM⁺ stretching) of MESHPIE and NFPU-IL (used as reference). f Molecular electrostatic potential (MESP) of MESHPIE molecule and ion pair to predict the possible interaction site. g Complexation energy via quantum chemical computing of imidazolium cation [BMIM]⁺ in the presence of counter anion [TFSI]^– with C–F group to investigate the relative stability of their interactions. h The atoms of the complexes according to their contributions to the intermolecular interactions. Dark blue indicates no contribution to the complexation, and dark red indicates the largest relative contribution.