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FTIR spectral analysis of solvation effects on the absorption frequencies of N H stretching vibrations of pyrrole as well as its complexes with proton acceptors (B) was carried out. The comparative analysis of the influence of solvation effects on the absorption frequencies of N H groups of pyrrole and O H groups of methanol in aprotic solvents for both free and bound molecules was carried out. The process of transferring the complexes to proton donor solvent, chloroform, which leads to a change in the strength of X H…B (where X = O or N) hydrogen bonds due to the manifestation of cooperative interactions was studied. Contribution of the cooperativity effect of pyrrole and methanol complexes was found to differ.

The thermochemical study of hydrogen bonding of organic solutes in 1-methylimidazolium bis(trifluoromethylsulfonyl)imide ([MIM][NTf2]) was carried out. Activity coefficients at infinite dilution of organic compounds in [MIM][NTf2] were measured by gas-liquid chromatography at different temperatures between 303.15 and 343.15 K. The solution enthalpies of organic solutes in [MIM][NTf2] were determined from the temperature dependence of activity coefficients in the same systems. Solution enthalpies of solutes (propanol-1, meta-cresol, acetone, acetonitrile, diethyl ether, tetrahydrofuran, dichloromethane, trichloromethane, pyrrole) in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][NTf2] were measured by using high-precision solution calorimetry. The hydrogen bond enthalpies of organic solutes in [MIM][NTf2] and [BMIM][NTf2] were calculated using a previously developed method. The hydrogen bond enthalpies of organic solutes in the protic ionic liquid [MIM][NTf2] were compared with the values in the aprotic ionic liquid [BMIM][NTf2], as well as with those in the molecular solvent pyrrole. The hydrogen bond enthalpies of proton acceptor molecules in [MIM][NTf2] differ significantly from zero unlike in [BMIM][NTf2]. Hydrogen bond enthalpies of proton acceptor molecules in [MIM][NTf2] and pyrrole are close.

This work is devoted to the quantitative study of hydrogen bond formation of N-alkyl substituted ionic liquids with proton acceptor and proton donor organic solvents. 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [BMIM][NTf2], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], triethylsulfonium bis(trifluoromethylsulfonyl)imide [Et3S][NTf2], 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4] were investigated by solution calorimetry and FTIR-spectroscopy techniques. The stretching vibration region of C O group of 2-pentanone in mixture with N-alkyl substituted ionic liquid in inert solvent carbon tetrachloride was analyzed at different concentrations of components for the estimation of proton donor ability of ionic liquids. Also, the stretching vibration region of the OH-group of methanol was studied in a ternary system carbon tetrachloride (inert solvent), methanol (proton donor) and N-alkyl substituted ionic liquid for the estimation of proton acceptor ability of ionic liquids. The hydrogen bond enthalpy of methanol in ionic liquids was calculated using data of measured solution enthalpies and data extracted from the literature. The frequency shifts of the OH-group of methanol induced by intermolecular interactions within ionic liquids in a carbon tetrachloride solution were compared with the hydrogen bonding enthalpies of methanol with ionic liquids. A linear relationship between the frequency shifts of the OH-groups and hydrogen binding enthalpies of methanol in ionic liquids were found. According to measured FTIR-spectroscopy data, the N-alkyl substituted ionic liquids analyzed in this work possess weak proton donor properties, and at the same time their proton acceptor ability (basicity) is much higher and shows dependency on anion structure.

In this work, we have studied the thermochemistry of the hydrogen bond formation between ionic liquids and solute molecules. The solution enthalpies of several organic compounds (benzene, acetone, 3-picoline dimethylsulfoxide, formamide, N-methylformamide, acetamide, N-methylacetamide) in the series of ionic liquids with common anion bis(trifluoromethanesulfonyl)imide and different cations (1-butyl-3-methylimidazolium [BMIM][NTf2], 1-butyl-1-methylpyrrolidinium [BMPYR][NTf2], 1-butylpyridinium [BPY][NTf2], 1-butyl-1-methylpiperidinium [BMPIP][NTf2], trimethylpropylammonium [TMPAm][NTf2]) were measured by solution calorimetry at infinite dilution. The enthalpies of hydrogen bond between solutes and ionic liquids were determined by the previously proposed approach. The hydrogen bond enthalpies were correlated with the proton acceptor ability of ionic liquids from the Kamlet-Abboud-Taft equation and the proton donor ability of amides from the Abraham model. The proton donor ability and hydrogen bond reorganization of studied ionic liquids was analyzed. The formation of the hydrogen bond complexes of linear amides with ionic liquids with different compositions was shown. The effect of the ionic liquid structure on the strength of the hydrogen bond of linear amides with ionic liquids has been established.

In this work thermochemistry of solvation of mono-, di-, tri- and tetra-substituted benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]) ionic liquid was studied. Enthalpies of solution at infinite dilution of 34 substituted benzenes in [BMIM][BF 4 ] were measured at 298.15 K using solution calorimetry technique. Based on the experimental and literature data enthalpies of solvation of 36 substituted benzenes in [BMIM][BF 4 ] were calculated. It was shown that enthalpies of solvation of substituted benzenes in [BMIM][BF 4 ] are independent on the mutual position of subtituents and dipole moment of molecules. Group contribution scheme for prediction of enthalpies of solvation of substituted benzenes was applied. Values of methyl- (CH 3 ), tert -butyl- ( tert -C 4 H 9 ), bromo- (Br), iodo- (I), amino- (NH 2 ), methoxy- (OCH 3 ), dimethylamino- (N(CH 3 ) 2 ), methylcarboxylate- (COOCH 3 ) group contributions to the enthalpies of solvation in [BMIM][BF 4 ] were derived and compared with molecular solvents. Solvation enthalpies of substituted benzenes in [BMIM][BF 4 ] calculated through group contribution scheme were in good agreement with experimental data.

This work continues the development of the additive scheme for the calculation of solvation enthalpies of aromatic compounds in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). In this study, heterocyclic aromatic compound were selected as solutes. The solution enthalpies of 14 heterocyclic aromatic compounds in [BMIM][BF4] were measured at 298.15 K. Based on the experimental and literature data, the solvation enthalpies of heterocyclic aromatic compounds in [BMIM][BF4] were calculated. The contributions of the exchange of CH–group with –N=, >NH, >NCH3, –S–, and carbonyl >C=O substituent groups into the solvation enthalpies in [BMIM][BF4] were calculated. These values were compared with analogous contributions in benzene. Solvation enthalpies of heterocyclic aromatic compounds in [BMIM][BF4] calculated by the additive scheme were compared with experimental values, revealing a good agreement between calculated and experimental data. This fact indicates that group additive scheme for prediction of the solvation enthalpies can be successfully applied to heterocyclic aromatic compounds in ionic liquids.

Intermolecular interactions of organic solutes with a protic ionic liquid (1-methylimidazolium nitrate [MIM][NO3]) have been in focus of this work. Activity coefficients at infinite dilution of organic compounds in [MIM][NO3] were measured by gas-liquid chromatography at different temperatures between 303.15 and 343.15 K. Based on activity coefficients at infinite dilution of organic compounds in [MIM][NO3] the solution enthalpies were obtained. The solvophobic effect in protic ionic liquids was analyzed. It was shown the contribution of solvophobic effect on the solvation enthalpy in protic [MIM][NO3] is negligible. The hydrogen bond enthalpies of organic solutes in protic [MIM][NO3] and aprotic [EMIM][NO3] were calculated. The hydrogen bond enthalpies of organic solutes in the protic [MIM][NO3] and aprotic [EMIM][NO3] ionic liquids were compared. The hydrogen bond enthalpies of proton acceptor molecules in [MIM][NO3] and [EMIM][NO3] ionic liquids were analyzed.

In this work solution enthalpies of aromatic compounds and their halogen derivatives in 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [BMIM][NTf2], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO] were measured by solution calorimetry method. The solvation enthalpies of aromatic compounds and their halogen derivatives in ionic liquids were calculated. Based on experimentally measured solvation enthalpies and calculated non-specific solvation enthalpy the contribution of the solvophobic effect on the solvation enthalpy of dissolved molecules in ionic liquids was demonstrated to be negligible. The correlation between solvation enthalpies of the aromatic compounds and their halogen derivatives in ionic liquids and solute molecules polarizability parameter was found. Also, a comparison of relationships between solvation enthalpy and molar refractions in ionic liquids and molecular solvents was made.