1,3-Bis(carboxymethyl)imidazolium bis(trifluoromethylsulfonyl)imide organic salt: Synthesis, single crystal structure, vibrational spectra, DFT calculations and physical-chemical properties

• The crystal structure of 1,3-bis(carboxymethyl)imidazolium bis(trifluoromethylsulfonyl)imide organic salt was determined.
• Its solubility in water is higher by about 10 ∼ 20 times than that of N–alkyl-imidazolium TFSI.
• High designability of ionic liquid was verified.

The bis(trifluoromethylsulfonyl)imide anion (TFSI) is one of the common anions forming hydrophobic ionic liquids at room temperature. In this work, through an introduction of two carboxyl groups into the imidazolium cation, a hydrophilic 1,3-bis(carboxymethyl)imidazolium bis(trifluoromethylsulfonyl)imide (BCITFSI) organic salt was synthesized and its crystal structure, vibrational spectra, physical-chemical properties such as thermal stability, pKa and solubility in water were experimentally determined. Present results are suggesting a possibility to tune the properties of ionic liquids by an appropriate change in cation structure, leading to new “designer solvents”.

We synthesized a hydrophilic 1,3-bis(carboxymethyl)imidazolium bis(trifluoromethylsulfonyl)imide organic salt by the introduction of two carboxyl groups into the imidazolium cation, and determined its crystal structure, FT-IR and Raman spectra, and thermal properties. Its solubility in water is higher by about 10 ∼ 20 times than that of the common N–alkyl-imidazolium TFSI ionic liquid. This result indicates that the ionic liquids have high designability, and can be used for a specific purpose by the modification of physical and chemical properties.Figure optionsDownload as PowerPoint slide