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In this work, we describe the synthesis, interactions with bovine serum albumin, and cytotoxicity of new ionic liquids based on 5-fluorouracil (API-ILs) with different cations (imidazolium, choline, isoquinolinium, guanidinium). The secondary and tertiary structure of BSA in solutions with different concentrations of API-ILs was monitored by the circular dichroism (CD) technique. The addition of API-ILs does not lead to structural changes in BSA. A quenching of fluorescence spectra intensity of BSA in presence of all API-ILs was observed, allowing the quantification of binding between API-ILs and BSA. The preferred localization of both ions in API-ILs differs significantly depending on the structure of the cation according to molecular docking. The aggregation of BSA in presence of API-ILs was analyzed by the dynamic light scattering (DLS) method, revealing a moderate increase in particle size. Cytotoxicity and selectivity of API-ILs on cancer and normal cell lines were estimated, showing a clear modification of the pharmaceutic activity of ionic liquid compared to 5-fluorouracil. [ABSTRACT FROM AUTHOR]

Abstract The thermochemical study of hydrogen bonding of organic solutes in 1-methylimidazolium bis(trifluoromethylsulfonyl)imide ([MIM][NTf 2 ]) was carried out. Activity coefficients at infinite dilution of organic compounds in [MIM][NTf 2 ] were measured by gas-liquid chromatography at different temperatures between 303.15 and 343.15 K. The solution enthalpies of organic solutes in [MIM][NTf 2 ] 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][NTf 2 ] were measured by using high-precision solution calorimetry. The hydrogen bond enthalpies of organic solutes in [MIM][NTf 2 ] and [BMIM][NTf 2 ] were calculated using a previously developed method. The hydrogen bond enthalpies of organic solutes in the protic ionic liquid [MIM][NTf 2 ] were compared with the values in the aprotic ionic liquid [BMIM][NTf 2 ], as well as with those in the molecular solvent pyrrole. The hydrogen bond enthalpies of proton acceptor molecules in [MIM][NTf 2 ] differ significantly from zero unlike in [BMIM][NTf 2 ]. Hydrogen bond enthalpies of proton acceptor molecules in [MIM][NTf 2 ] and pyrrole are close. Graphical abstract Unlabelled Image Highlights • Activity coefficients of organic solutes in [MIM][NTf 2 ] at five temperatures were measured. • The hydrogen bond enthalpies of proton acceptor solutes in [MIM][NTf 2 ] were determined. • Solution enthalpies of solutes in [BMIM][NTf 2 ] were measured by solution calorimetry. • The N H fragment of [MIM][NTf 2 ] and pyrrole exhibits similar proton donor ability. [ABSTRACT FROM AUTHOR]

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][NTf 2 ], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 ], triethylsulfonium bis (trifluoromethylsulfonyl)imide [Et3S][NTf 2 ], 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF 4 ] 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. [ABSTRACT FROM AUTHOR]

• The stability of BSA and HSA in cholinium-based ILs with biological origin anions has been study. • Biomolecular interactions between BSA/HSA and ILs was estimated. • The role of methylene group in anion of ILs was established. • Cytotoxicity of ILs on cancer and normal cell lines was analyzed. The intermolecular interactions of cholinium-based ionic liquids (ILs) with biological origin anions (amino and dicarboxylic acids) with bovine serum albumin (BSA) and human serum albumin (HSA) have been studied by spectral and computational methods. The choline malonate ([Ch][Mal]), choline succinate ([Ch][Suc]) and choline valinate ([Ch][Val]) were synthesized. The changes to the state of the BSA and HSA with ILs at different concentration were observed using circular dichroism (CD) spectroscopy. At higher concentrations the ILs lead to a partial loss of ternary structure of albumins. The effect of ILs on the thermal stability of proteins was monitored by the temperature CD spectra scans. The increase of denaturation temperature of albumins with ionic liquids was observed. The interaction of ionic liquids with serum albumins was estimated by fluorescence spectroscopy technique, while the probable binding modes were identified using molecular docking. The leading cause of the increased thermal stability of albumins was found to be the formation of aggregates of proteins with ionic liquids. Cytotoxicity of ionic liquids on cancer and normal cell lines was established. [ABSTRACT FROM AUTHOR]

• The effect of ILs on BSA was analyzed by spectral and computational methods. • The imidazolium- and cholinium-based ILs promote aggregation of BSA. • The stability of the tertiary structure of BSA is enhanced by the studied ionic liquids. • IL with octyl chain binds to BSA and does not increase its stability. The present work describes the effect of imidazolium- and cholinium-based ionic liquids (ILs) on the thermal stability, binding and aggregation of bovine serum albumin (BSA). The studied ILs include choline chloride [Ch][Cl], choline dihydrogenphosphate [Ch][DHP], choline acetate [Ch][OAc], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF 4 ] 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium acetate [BMIM][OAc], and 1-butyl-3-methylimidazolium methanesulfonate [BMIM][CH 3 SO 3 ]. The state of BSA in presence of ILs was assessed by circular dichroism (CD), temperature dependent circular dichroism, fluorescence spectroscopy, and dynamic light scattering (DLS). The thermal stability of BSA in presence of ILs increased (above 85 °C) in all studied ILs except [OMIM][BF 4 ]. Differences of binding ILs with BSA depending on alkyl chain length were estimated, the probable binding modes were identified using molecular docking. The influence of ILs on the aggregation of BSA at different temperatures was established. It was found that the ILs with short alkyl chain length (up to butyl) promote aggregation of the native form of BSA increasing its thermal stability. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work thermochemistry of solution and solvation of mono- and di-substituted chloro- and nitro-benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][TfO]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquids was studied. Enthalpies of solution at infinite dilution of benzene, chlorobenzene, nitrobenzene, 1,2-, 1,3-, 1,4-dichlorobenzenes, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1-chloro-2-nitrobenzene, 1-chloro-3-nitrobenzene, and 1-chloro-4-nitrobenzene in three ionic liquids were measured at 298.15 K. On the basis of experimental data enthalpies of solvation of substituted benzenes in ionic solvents were calculated. Values of Cl and NO 2 group contributions to the enthalpies of solvation were derived and compared with molecular solvents. Enthalpies of solvation of each series of dichlorobenzenes, chloronitrobenzenes and dinitrobenzenes in studied ionic liquids are equal and do not depend on the mutual position of substituents. This fact shows that dipole moment does not affect the enthalpy of solvation of organic solutes in ionic liquids. Enthalpies of solvation of disubstituted benzenes in ionic liquids calculated through group contribution approach were in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

In this work the thermodynamics of intermolecular interactions for imidazolium based ionic liquids in solutions of proton donor solvent chloroform and proton acceptor solvent tetrahydrofuran was studied using solution calorimetry technique. Enthalpies of solution of 1-ethyl- and 1-butyl-3-methylimidazolium based ionic liquids with tetrafluoroborate, methylsulfate, ethylsulfate, butylsulfate, dicyanoamide, trifluoromethanesulfonate, thiocyanate anions were measured in two solvents over concentration range 0.18-3.60 mmol kg −1 at 298.15 K. Enthalpies of transfer from tetrahydrofuran to chloroform derived from experimental data were exothermic for all studied ionic liquids. Proton acceptor scale of ionic liquids as solutes was proposed on the basis of thermochemical data. Enthalpy of hydrogen bonding of ionic liquids with proton donor solvent chloroform increases in the range of anions [BF 4 ] − < [SCN] − < [TfO] − < [N(CN) 2 ] − < [AlkSO 4 ] − . At the same time these values remain constant for ILs with different length of alkyl group in cations and anions. Thermochemical proton acceptor scale of ILs in solution correlates well with COSMO-RS hydrogen-bonding energies in equimolar cation–anion pairs of ILs. [ABSTRACT FROM AUTHOR]

In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n -alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • The changes to the state of the lysozyme molecule were observed using capillary DSC and CD spectroscopy. • The fluorescence spectroscopy and molecular docking data indicate a lack of strong binding between the studied ILs and HEWL. • The hydrogen bond enthalpies of methanol in ionic liquids and the denaturation temperature of HEWL are linearly correlated. The intermolecular interactions of imidazolium- and cholinium-based ionic liquids and hen egg-white lysozyme (HEWL) were studied by spectral, thermodynamic, and computational methods. The cholinium- and imidazolium-based ionic liquids: choline chloride [Ch][Cl], choline dihydrogenphosphate [Ch][DHP], choline acetate [Ch][OAc], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium acetate [BMIM][OAc] and 1-butyl-3-methylimidazolium methanesulfonate [BMIM][CH 3 SO 3 ] were selected. The proton donor and acceptor abilities of ionic liquids were determined based on gas chromatography and solution calorimetry data. The temperature denaturation of HEWL in ionic-liquid solution was observed using capillary differential scanning calorimetry (DSC) and circular dichroism spectroscopy (CD). The interaction of ionic liquids with HEWL at the standard temperature was accessed by monitoring the protein's fluorescence changes. The effect of the ionic liquid on the stability of the native structure of HEWL strongly depends on the proton acceptor ability of ionic liquids. The denaturation temperature of the native structure HEWL is linearly correlated with the enthalpy of the specific interaction (hydrogen bonding) of methanol and trichloromethane in the studied ionic liquids. At the same time, fluorescence data revealed ionic liquid-specific effects, which depend on both ions in the ionic liquid. Both fluorescence and molecular docking data indicate a lack of strong binding between the studied ionic liquids and HEWL. [ABSTRACT FROM AUTHOR]

[Display omitted] • The solution enthalpies of amides and proton acceptors in ionic liquids were measured. • The proton donor ability of studied ionic liquids was analyzed. • The hydrogen bond formation between proton acceptor and ionic liquids with different cation was shown. • The hydrogen bond enthalpies were correlated with independent scales of proton acceptor and the proton donor ability. 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][NTf 2 ], 1-butyl-1-methylpyrrolidinium [BMPYR][NTf 2 ], 1-butylpyridinium [BPY][NTf 2 ], 1-butyl-1-methylpiperidinium [BMPIP][NTf 2 ], trimethylpropylammonium [TMPAm][NTf 2 ]) 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. [ABSTRACT FROM AUTHOR]

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][BF 4 ]). In this study, heterocyclic aromatic compound were selected as solutes. The solution enthalpies of 14 heterocyclic aromatic compounds in [BMIM][BF 4 ] were measured at 298.15 K. Based on the experimental and literature data, the solvation enthalpies of heterocyclic aromatic compounds in [BMIM][BF 4 ] were calculated. The contributions of the exchange of CH–group with –N=, >NH, >NCH 3 , –S–, and carbonyl >C=O substituent groups into the solvation enthalpies in [BMIM][BF 4 ] were calculated. These values were compared with analogous contributions in benzene. Solvation enthalpies of heterocyclic aromatic compounds in [BMIM][BF 4 ] 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. Unlabelled Image • The solution enthalpies of 14 heterocyclic aromatic compounds in [BMIM][BF 4 ] were measured The group additivity approach was applied for the prediction of the solvation enthalpies compounds in [BMIM][BF 4 ] • Solvation enthalpies obtained by the group contribution approach were in good agreement with experimental data • The group additivity approach was applied for the prediction of the solvation enthalpies compounds in [BMIM][BF 4 ]. [ABSTRACT FROM AUTHOR]

• The solution enthalpies of amides in ionic liquids were measured. • The specific interaction enthalpies of amides in ionic liquids were calculated. • The hydrogen bond enthalpies of amides in ionic liquids and organic solvents were compared. The present work focuses on hydrogen bonding of linear and cyclic amides (formamide, N -methylformamide, acetamide, N -methylacetamide, N,N -dimethylacetamide, 2-pyrrolidone) in several ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [BMIM][NTf 2 ], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 ], triethylsulfonium bis(trifluoromethylsulfonyl)imide [Et 3 S][NTf 2 ], Trimethylpropylammonium bis(trifluoromethylsulfonyl)imide [TMPAm][NTf 2 ]). The solution enthalpies of amides in ionic liquids were measured by solution calorimetry at infinite dilution. The hydrogen bond enthalpies were calculated based on solution enthalpies of amides in ionic liquids. The hydrogen bond enthalpies of linear and cyclic amides in ionic liquids and organic proton acceptors were compared. The influence of active proton donor center on the formation of hydrogen bond complexes between amides and ionic liquids was analyzed. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of hydrogen bond formation ability of ionic liquids. The proton donor abilities of pyrrolidinium-based ionic liquids with common anion bis(trifluoromethylsulfonyl)imide ([NTf 2) and a range of cations, i.e. 1-Methyl-1-ethylpyrrolidinium [MEPyr][NTf 2 , 1-Methyl-1-propylpyrrolidinium [MPrPyr][NTf 2 , 1-Methyl-1-butylpyrrolidinium [MBPyr][NTf 2 , 1-Methyl-1-octylpyrrolidinium [MOPyr][NTf 2 were studied by FTIR spectroscopy. The proton acceptor abilities of several ionic liquids (1-Butyl-3-methylimidazolium bis (trifluoromethanesulfonyl)imide [BMIM][NTf 2 , 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 , 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 , triethylsulfonium bis (trifluoromethylsulfonyl)imide [Et 3 S][NTf 2 , 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF 4) were studied by both FTIR and solution calorimetry techniques. The hydrogen bond enthalpies of pyrrole in various ionic liquids were calculated. A linear correlation between frequency shifts of H-bonded NH-group of pyrrole in ionic liquids and hydrogen bond enthalpies of pyrrole in the same ionic liquids was found. The obtained correlation for ionic liquids was compared with molecular organic solvents. Unlabelled Image • The pyrrolidinium-based ILs cannot form hydrogen bond with proton donor molecules. • The hydrogen bond enthalpy of pyrrole in ionic liquids was calculated by solution calorimetry. • The frequency shifts of NH-group of pyrrole in ionic liquids were measured by FTIR-spectroscopy. • Linear correlation between frequency shifts of H-bonded OH-group of pyrrole in complexes with ionic liquids was found. [ABSTRACT FROM AUTHOR]

Intermolecular interactions of organic solutes with a protic ionic liquid (1-methylimidazolium nitrate [MIM][NO 3 ]) have been in focus of this work. Activity coefficients at infinite dilution of organic compounds in [MIM][NO 3 ] 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][NO 3 ] 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][NO 3 ] is negligible. The hydrogen bond enthalpies of organic solutes in protic [MIM][NO 3 ] and aprotic [EMIM][NO 3 ] were calculated. The hydrogen bond enthalpies of organic solutes in the protic [MIM][NO 3 ] and aprotic [EMIM][NO 3 ] ionic liquids were compared. The hydrogen bond enthalpies of proton acceptor molecules in [MIM][NO 3 ] and [EMIM][NO 3 ] ionic liquids were analyzed. Unlabelled Image • Activity coefficients at infinite dilution of organic compounds in [MIM][NO 3 ] were measured. • The contribution of solvophobic effect on the solvation enthalpy in [MIM][NO 3 ] is negligible. • The hydrogen bond enthalpies of organic solutes in [MIM][NO 3 ] and [EMIM][NO 3 ] ionic were compared. [ABSTRACT FROM AUTHOR]

In this work solution enthalpies of aromatic compounds and their halogen derivatives in 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [BMIM][NTf 2 ], 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. Unlabelled Image • Solution enthalpies of solutes in ionic liquids were measured by solution calorimetry. • Non-specific solvation enthalpies of solutes in ionic liquids were calculated. • Contribution of solvophobic effect on solvation enthalpy were determined. • Correlation between solvation enthalpies of aromatic compounds and their halogen derivatives in ionic liquids was found. [ABSTRACT FROM AUTHOR]