H-Bonding structures of 1-ethyl-3-methylimidazolium trifluoroacetate: a vibrational spectroscopic study

. The appearance of cross-peak features in the time-zero 2DIR spectra indicates the presence of intermolecular coupling between the CO stretching modes of TFA anions, which can be expected for such pure IL systems. When diluted in polar aprotic solvents, Emim:TFA exists predominantly in ion pairs, while in polar protic solvents solvent-separated ions are the dominant species. The existence of significant ionic aggregation is only visible in the neat ionic liquid.