Infrared Spectroscopy of Ionic Liquids Consisting of Imidazolium Cations with Different Alkyl Chain Lengths and Various Halogen or Molecular Anions with and without a Small Amount of Water

Abstract

Infrared spectroscopy was performed on ionic liquids (ILs) that had imidazolium cations with different alkyl chain lengths and various halogen or molecular anions with and without a small amount of water. The molar concentration normalized absorbance due to C-H vibrational modes in the range of 3000 to 3200 cm was nearly identical for ILs that had imidazolium cations with different alkyl chain lengths and the same anions. A close correlation was found between the red-shifted C-H vibrational modes, the chemical shift ofC(2)-H proton, and the energy stabilization of the hydrogen-bonding interaction. The vibrational modes of the water molecules interacting with anions in the range between 3300 and 3800 cm was examined. The correlation between the vibrational frequencies of water, the frequencies of C-H vibrational modes, and the center frequency of intermolecular vibrational modes due to ion pairs was discussed.

Aramid pulp reinforced hydrogenated nitrile butadiene rubber composites with ionic liquid compatibilizers

“…Imidazolium ring stretching modes within 1564–1164 cm −1 are seen for both imidazolium salts, and the strong band at 1715 cm −1 is attributed to the symmetric stretching modes of carbonyl group from HO 2 CC 1 MImCl . Also, water absorption in C 4 MImCl produced a broad O‐H peak at about 3400 cm −1 …”

An insight into the intermolecular vibrational modes of dicationic ionic liquids through far-infrared spectroscopy and DFT calculations

“…26 The frequency range between 2 and 300 cm À1 involves intermolecular forces and can be studied by different experimental methods such as optical heterodyne-detected Raman-induced Kerr-effect spectroscopy (OHD-RIKES), 27-32 dielectric relaxation spectroscopy (DRS), [32][33][34] terahertz (THz) spectroscopy, [35][36][37][38][39] low-energy neutron scattering, 40 X-ray diffraction, 41 far infrared (FIR) spectroscopy and Raman spectroscopy. 36,38,[42][43][44][45][46][47] It is worth mentioning that ILs' experimental spectra are usually difficult to interpret as a result of the complex combination of overlapping bands. Therefore, theoretical methods are oen needed to assign specic vibrational motions.…”

Assessment of in vitro cytotoxicity of imidazole ionic liquids and inclusion in targeted drug carriers containing violacein

“…At low frequencies range (500-670 cm À1 ) intensities are low and displayed many peaks as previously reported. 43 This region displayed intramolecular vibrational modes of the skeletal vibration of the imidazolium ring, two peaks in this region showed a hypsochromic shis from 549.3 cm À1 to 555.9 cm À1 , and 519 cm À1 to 523.9 cm À1 , and two bathochromic shis from 540.7 cm À1 to 537.8 cm À1 and 633.6 cm À1 in pure IL to 631.2 cm À1 in the complex. In the 700-900 cm À1 region peaks corresponding to C-H bending in rings described before in both [C 16 Him] and Viol fused peaks are observed, 724.8 cm À1 peak in [C 16 Him] and 730.7 cm À1 peak in Viol appear as one peak at 726.3 cm À1 , in a similar way, 766.4 cm À1 peak in [C 16 Him] and 759.0 cm À1 in Viol appear as one peak at 767.4 cm À1 in the mixture, and 870.8 cm À1 and 868.0 cm À1 appear as one peak at 866.4 cm À1 .…”

“…Complex and wide peak at higher frequencies comprises different and highly overlapped N-H and O-H stretching frequencies (2851.8 cm À1 , 2925.4 cm À1 , 3050.5 cm À1 and 3175.4 cm À1 ). 2,42,43 Several shis were observed in equimolar mixture [Viol-(C 16 Him-S)] and a complex spectrum was observed ( Fig. 3C).…”