The structural organization in aqueous solutions of ionic liquids

Zhu, Xiao; Wang, Yong; Li, Haoran

doi:10.1002/aic.11645

Cited by 35 publications

(37 citation statements)

References 46 publications

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“…Various approaches have been employed to investigate the interaction between ILs and water including experimental techniques [6][7][8][9][10][11][12][13], as well as theoretical calculations [14][15][16] and molecular dynamics simulation [17][18][19][20][21]. Specially, NMR method has been frequently utilized to probe intra-and intermolecular interactions of ILs/water mixtures [21][22][23][24]. However, there are few NMR chemical shift data over the whole composition range for ILs/water mixtures.…”

Section: Introductionmentioning

confidence: 99%

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Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

Gao

Zhang

et al. 2010

Sci. China Chem.

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The relative chemical shifts () were put forward to investigate the microscopic structure of 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EmimBF 4 ) during the dilution process with water. The concentration-dependent  (C2)H(C4)H ,  (C2)H(C5)H and  (C4)H(C5)H were analyzed. The results reveal that the variations of the microscopic structures of three aromatic protons are inconsistent. The strength of the H-bond between water and three aromatic protons follows the order: (C2)H···O > (C4)H···O > (C5)H···O. The concentration-dependent  (C6)H(C7)H and  (C6)H(C8)H indicate the formation of the H-bonds of (C alkyl )H···O is impossible, and more water is located around (C6)H than around (C7)H or (C8)H. The concentration-dependent  (C2)H(C4)H and  (C2)H(C5)H both increase rapidly when x water > 0.9 or so, suggesting the ionic pairs of EmimBF 4 are dissociated rapidly. The turning points of concentration-dependent  (C2)H(C4)H and  (C2)H(C5)H indicate that some physical properties of the EmimBF 4 /water mixtures also change at the corresponding concentration point. The microscopic structures of EmimBF 4 in water could be clearly detected by the relative chemical shifts.ionic liquids, 1 H NMR, microscopic structure, relative chemical shifts, 1-ethyl-3-methyl-imidazolium tetrafluoroborate

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Section: Introductionmentioning

confidence: 99%

“…We have described in recent publications the microscopic local composition of ILs/water mixtures focusing on 1 H NMR chemical shift combined with the local composition (LC) model [23]. Ionic liquids involve 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF 4 ) and n-butylammonium nitrate (N4NO 3 ) (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

Gao

Zhang

et al. 2010

Sci. China Chem.

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“…Obviously, as is shown in Fig. 1, the -CH 3 chemical shifts of N 222 NO 3 in solutions can be well correlated by this semi-empirical LC model, just as its excellent performance in the aqueous solutions of n-butylammonium nitrate (N 4 NO 3 ) [23] and EmimBF 4 [24] ionic liquids.…”

Section: Correlation Of 1 H Nmr Chemical Shiftsmentioning

confidence: 59%

“…Subsequently, relations between the thermodynamic and spectroscopic properties of mixtures have been established successfully with this LC model [20][21][22]. In our previous work, IR, Raman and 1 H NMR measurements were made in solutions of ILs [23] and the local structure of aqueous solutions of 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF 4 ) and n-butylammonium nitrate (N4NO 3 ) [24] were studied using the LC model.…”

Section: Introductionmentioning

confidence: 99%

Structural Heterogeneities in Solutions of Triethylamine Nitrate Ionic Liquid: 1H NMR and LC Model Study

Zhu

Zhang

2016

J Solution Chem

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In order to uncover the micro-structural heterogeneities in solutions of ammonium based ionic liquids, triethylamine nitrate (N 222 NO 3 ) has been synthesized using acid-base neutralization and the 1 H NMR spectra of two binary mixtures, namely N 222 NO 3 /dimethyl sulfoxide (DMSO) and N 222 NO 3 /acetone at different concentrations, have been measured at 298.15 K. The internal reference method was adopted to obtain the concentration-dependent chemical shifts of -CH 3 in N 222 NO 3 , which have been correlated using the 1 H NMR local composition (LC) model to obtain the local mole fractions. It has been revealed that within N 222 NO 3 rich region, self-association of the ionic liquid was predominant instead of N 222 NO 3 -solvent interactions. However, in the solvent rich region, N 222 NO 3 mainly interacts with solvent molecules, indicating that the self-association network of N 222 NO 3 has been greatly destroyed by solvents. In addition, the different influences of DMSO and acetone have been detected. DMSO molecules more effectively destroy the original network of the ionic liquid, due to its higher dielectric constant. Also, LC behavior in N 222 NO 3 /DMSO systems is more significant than in N 222 NO 3 /acetone, indicating that DMSO can induce more obvious heterogeneities in DMSO/N 222 NO 3 mixtures, which is consistent with physicochemical properties and cellulose solubility of solutions.

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“…[15] Therefore, the hydrogen-bonding interaction of C2ÀHo f[ C n mim]BF 4 is often used to represent the intermolecular interaction of the cation. [14,19] For example, in our previousw ork, [14] the local compositiono f1 -ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF 4 )i n[ Emim]BF 4 -water mixture has been calculated by using the interaction-energy parameter obtained from the 1 HNMR chemical shifts of C2ÀH and hasb een compared with the bulk composition. This comparisons howed that the differenceb etween the local and bulk composition of [Emim]BF 4 presented the turnover at x IL % 0.6, which was in accordance with the change of excessm olar volumes of the system.A lthough the hydrogen-bonding interaction of C2ÀHc ould partly represent the intermolecular interaction of the cation of [Emim]BF 4 ,itfailed to establish the quantitative relationships between the microstructure and physicochemicalp roperties, [14] thus suggesting that the interaction of C2ÀHa loned oes not representt he whole interaction of the cation.…”

Section: Introductionmentioning

confidence: 99%

The Effect of C4H and C5H on the Microstructure of Aqueous Solutions of 1‐Alkyl‐3‐methylimidazolium Tetrafluoroborate Ionic Liquids

2015

ChemPhysChem

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As is well-known, the C2H proton of 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF ) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF ) has a strong ability to form hydrogen bonds. The purpose of this work is to evaluate the effect of the interactions of the C4H and C5H protons on the microstructure of [Emim]BF and [Bmim]BF with water by using H NMR spectroscopy. The differences between the relative H NMR chemical shifts of C2H, C4H, and C5H and between the interaction-energy parameters obtained from these chemical shifts are minor, thus suggesting that the interactions of C4H and C5H may have a considerable effect on the microstructure. To confirm this, the viscosities of the systems are estimated by using the interaction-energy parameters obtained from the H NMR chemical shifts of the three studied aromatic protons and water, showing that the interactions of C4H and C5H also play an important role in the microstructure.

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The structural organization in aqueous solutions of ionic liquids

Cited by 35 publications

References 46 publications

Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

Microscopic structures of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate in water probed by the relative chemical shift

Structural Heterogeneities in Solutions of Triethylamine Nitrate Ionic Liquid: 1H NMR and LC Model Study

The Effect of C4H and C5H on the Microstructure of Aqueous Solutions of 1‐Alkyl‐3‐methylimidazolium Tetrafluoroborate Ionic Liquids

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