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[Display omitted] The spectral characteristics of ethylene absorbed by ionic liquids (ILs) containing silver ions were studied by in situ ATR-FTIR spectroscopy at high pressure. Three different states of ethylene were observed based on the band shift of out-of-plane bending vibrations (ωCH 2) due to van der Waals interactions, hydrogen bonds, and π-complex formation with silver ions. Thus, ethylene can be used as an IR-sensitive probe molecule for characterizing interactions with ILs and other substances. [ABSTRACT FROM AUTHOR]

[Display omitted] • The simultaneous screening of multiple ionic liquids under controlled environment. • In situ ATR-FTIR spectroscopic imaging was used in high-throughput analysis of ILs. • ATR-FTIR imaging provides a platform for the simultaneous screening of multiple ILs. • Array of ILs was studied for sorption separately of water vapour and toluene vapour. • The information about ILs was obtained rapidly, quantitatively and simultaneously. In situ characterisation of ionic liquids under a controlled environment has been performed in a high throughput manner using macro ATR-FTIR spectroscopic imaging. 14 different ionic liquids with cations 1-butyl-3-methylimidazolium ([C 4 mim]), 1-butyl-2,3-dimethylimidazolium ([C 4 mmim]) and 1-butyl-3-methylpyrrolidinium ([C 4 C 1 pyrr]) and anions hexafluorophosphate ([PF 6 ]), tetrafluoroborate ([BF 4 ]), bis(trifluoromethylsulfonyl)imide ([NTf 2 ]), perchlorate ([ClO 4 ]), trifluoromethanesulfonate ([CF 3 SO 3 ]), nitrate ([NO 3 ]), methanesulfonate ([CH 3 SO 3 ]) and trifluoroacetate ([TA]) were studied. The ionic liquids were deposited onto the measuring surface of the ATR crystal in the corresponding accessory hosted in the FTIR imaging system. Then these samples were exposed to a controlled environment of toluene and water vapour and spectra acquired simultaneously. Changing the structure of the cation head group from [C 4 mim] to [C 4 mmim] or [C 4 C 1 pyrr] only had a small effect on the toluene absorption while increasing the length of the alkyl chain of the cation (e.g. [C 10 mim]) has shown a significant increase in toluene absorption. The ionic liquids with the anion [NTf 2 ] were found to absorb the highest amount of toluene followed by [CF 3 SO 3 ], then [PF 6 ], [ClO 4 ], [NO 3 ] and [TA], and the lowest amount of toluene was absorbed in ionic liquids with [BF 4 ] or [CH 3 SO 3 ] anions. The amount of water absorbed increases in the order: [C 4 mim][CH 3 SO 3 ] > [C 4 mim][TA] > [C 4 mim][NO 3 ] > [C 4 mim][CF 3 SO 3 ] > [C 4 mim][ClO 4 ] ~ [C 4 mim][BF 4 ] ~ [C 4 mmim][BF 4 ] > [C 10 mim][BF 4 ] > [C 4 mim][PF 6 ] ~ [C 4 mmim][PF 6 ] > [C 4 mim][NTf 2 ] ~ [C 4 mmim][NTf 2 ] ~ [C 4 C 1 pyrr][NTf 2 ]. This work has demonstrated that spectroscopic imaging provides a platform for the simultaneous screening of multiple ionic liquids in situ, when under controlled environments. [ABSTRACT FROM AUTHOR]

In this work, in situ ATR-FTIR spectroscopy was used to study the interaction of CO 2 and a series of 1-alkyl-3-methylimidazolium tetrafluoroborate С n MIMBF 4 (n = 2, 4, 6, 8, 10) ionic liquids. A detailed analysis of the infrared spectra acquired from ionic liquids and sorbed СО 2 was performed as ionic liquids with different the alkyl chain lengths were subjected to changing pressures of СО 2 and temperature. With a longer alkyl chain length, an increase in the shift of the CH stretching vibrations bands of alkyl groups and BF stretching vibrations of BF 4 − anions is observed during CO 2 sorption. This indicates the disaggregation of alkyl chains and anions. There is a correlation with the position of the wavenumber of the ν 3 asymmetric stretching CO 2 band and the length of the alkyl chain. It was found that some of the CO 2 adsorbed by ionic liquids does not interact with the ionic liquid but is "free" in the bulk of the alkyl chains. For the first time, ATR-FTIR spectroscopy was used to determine the thermodynamic parameters of CO 2 sorption in ionic liquids. It was demonstrated that the values of enthalpy and entropy obtained by analysis of the ATR-FTIR spectra are consistent the data obtained by other methods. A correlation was found between the enthalpy of sorption of CO 2 and the wavenumber of the ν 3 band. This opens up the possibility of using CO 2 as an IR-sensitive probe molecule to characterize the acid-base properties of ionic liquids and determine the enthalpy of CO 2 sorption. Unlabelled Image • In situ ATR-FTIR spectroscopy was used to study CO 2 sorption in a homologous series of ionic liquids. • ATR-FTIR spectroscopy was used to determine the thermodynamic parameters of CO 2 sorption in ionic liquids. • A correlation was found between the enthalpy of CO 2 sorption and the wavenumber of the ν 3 band of CO 2. • CO 2 can be used an IR-sensitive probe molecule to characterize the properties of ionic liquids. [ABSTRACT FROM AUTHOR]