Theoretical Exploration of the Role of CO2 in an Imidazolium Cation-Based Ionic Liquid

Optimized structures of imidazolium cation-based ionic liquids (ILs) and CO2 were obtained using the Gaussian 09 software package and density functional theory (B3LYP/6-31+G(d,p)) with dispersion correction. The interaction energy between cation and anion for imidazolium cation-based ILs, as well as that between ILs and CO2 , were estimated to investigate specific interactions. The presence of CO2 highly impacts the formation of the optimized geometry of imidazolium-based IL. The wavenumber of the C2-H stretching frequency in the imidazolium cation was calculated. The shift of the C2-H stretching wavenumber verified the strong interaction of CO2 with imidazolium and halogen based ILs.