INTERACTION OF IONIC LIQUIDS BASED ON BIS(TRIFLUOROMETHYLSULFONIL)IMIDE ANION WITH HALLOYSITE NANOTUBES ACCORDING TO FT-IR SPECTROSCOPY

Abstract

In this work, FT-IR spectroscopy was used to study the interactions in ionogels of the composition х[X]+[TFSI]−/(100 - x)НNT, where [TFSI]– is the bis(trifluoromethylsulfonyl)imide anion, the cation [X]+ = [BMPip]+ (1-butyl-1-methylpiperidinium), [BMPyr]+ (1-butyl-1-methylpyrrolidinium), and [BMIm]+ (1-butyl-3-methylimidazolium), HNT are halloysite nanotubes, х = (55.2±0.5) wt.%. A comparison of the spectra of the starting compounds and the resulting ionogels showed that the characteristic frequency of the stretching vibrations of OH bonds of adsorbed water molecules, observed in the spectra of pure halloysite, practically vanishes in the spectra of ionogel sts. The stretching vibrations of the C-H bond atoms of the cation, ν(CH), and the stretching vibrations of the C-F bond atoms of the CF3 group of the anion, ν(CF3), in the spectra of limited ionic liquids are shifted to the high frequency region by 1-3 cm-1. The ratio of the intensities of the asymmetric bending vibrations of the S=O bond atoms of the SO2 group, I(δasopSO2)/I(δasipSO2), which correspond to two different conformational isomers of the anion, increases by (15-19)%. As a result, it was found that the H2O molecules of halloysite are replaced by molecules of the ionic liquid due to the electrostatic interaction of the cation with the negatively charged outer siloxane (–Si–O–Si–) surface of the nanotubes and hydrogen bonds (CH···OSi), and due to the electrostatic interaction of the anion with a positively charged internal aluminol (–Al–OH) surface and hydrogen bonds (CF···HO–Al, SO···HO–Al). The restriction of the ionic liquid in the internal cavity of the HNT causes a conformational rearrangement of the [TFSI]− anion. The results obtained are of fundamental importance, make a certain contribution to understanding the effects in ionogels based on ionic liquids and nanoporous natural minerals, and can be used to develop quasi-solid electrolytes in the production of various electrochemical devices. For citation: Ramenskaya L.M., Grishina E.P., Kudryakova N.O. Interaction of ionic liquids based on bis(trifluoromethylsulfonil)imide anion with halloysite nanotubes according to FT-IR spectroscopy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 36-44. DOI: 10.6060/ivkkt.20236603.6752.