Experimental Vibrational Study of Imidazolium-Based Ionic Liquids: Raman and Infrared Spectra of 1-Ethyl-3-methylimidazolium Bis(Trifluoromethylsulfonyl)imide and 1-Ethyl-3-methylimidazolium Ethylsulfate

Abstract

The vibrational structure of two room-temperature ionic liquids with the cation 1-ethyl-3-methylimidazolium [EMIM] and the respective anions bis(trifluoromethylsulfonyl)imide [TFSI] and ethylsulfate [EtOSO(3)] is investigated. In particular, attenuated total reflection (ATR) infrared (IR) as well as Raman spectra in the spectral range from 500 to 3500 cm(-1) have been recorded and analyzed. Moreover, the depolarization ratios of the Raman lines are determined. The individual peaks are assigned to the corresponding vibrational modes of the molecules. While the CH stretching region around 3000 cm(-1) is dominating in Raman spectra, it is remarkably weak in IR spectra. Finally, the results for 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are compared to previous studies of single ions available in the literature. This comparison shows good agreement.

Aging Effects on the Properties of Imidazolium-, Quaternary Ammonium-, Pyridinium-, and Pyrrolidinium-Based Ionic Liquids Used in Fuel and Energy Production

“…This evidence supports the ring opening of the pyridinium and polymerization of the system and is further backed by the physical observations. This also corresponds with an inverse in intensity of the peaks at approximately 1210cm -1 and 1160cm -1 , the latter due to the CF 3 antisymetric stretch and the former due to the CF 3 symmetric stretch 32 .…”

Investigation of polymer electrolyte based on agar and ionic liquids

“…The broadband at 3416 cm -1 , attributed to the stretching of OH hydroxyl groups of agar that participate in hydrogen bond formation in inter-and intramolecular bonds or in hydrogen inter and intramolecular bond formation, shifts to shorter wavelengths numbers with the addition of ILs [20,21]. The bands at 2934 and 2887 cm -1 refer to the CH asymmetrical stretching, which increase in intensity due to its presence in both glycerol and in the ILs [22,23]. The band at 2360 cm -1 is due to the CO 2 from air and at 1653 cm -1 is due to adsorbed water.…”

“…The stretching of the COH alcohol bond shifts from 1087 to 1038 cm -1 , which is probably due to the hydrogen bond formation between glycerol and macromolecule. Other bands from 920 to 960 cm -1 , depending on the sample, can be assigned to C-O-SO 3 or C-C stretching from polymer ring [26] and at 780; 790 cm -1 to IL ring HCCH symmetric bending [22] or 3,6-anhydro-!-galactose skeletal bending [26].…”

Effects of C(2) Methylation on Thermal Behavior and Interionic Interactions in Imidazolium-Based Ionic Liquids with Highly Symmetric Anions

“…The detailed vibrational analysis and tentative assignments are summarized in Tables A1 and A2 in the appendix. The assignments are based on previous work and the references therein [6,19,30]. In the following, we focus on a discussion of the interionic interactions.…”