EMIM Cations Research Articles

Charge compensation in a layered van der Waals NiPS3 host through various cationic intercalations

Electrochemical cation intercalation into 2D NiPS3 leads either to reduction of the (P2S6)4− units (Li example) or Ni cations (Na example), or causes electrochemical reduction and decomposition of EMIM cations within the van der Waals interlayers.

Hydrogen Bonding and Infrared Spectra of Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide/Water Mixtures: A View from Molecular Dynamics Simulations

Simulations of ab initio molecular dynamics have been performed for mixtures of ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) ionic liquid and water. Statistics of donors and acceptors of hydrogen bonds has revealed that with increasing water content, hydrogen bonds between EMIM cations and TFSI anions are replaced by bonds to water molecules. In the mixture of liquids, the total number of bonds (from EMIM cations or water molecules) formed by TFSI acceptors increases. IR spectra obtained from ab initio molecular dynamics trajectories are in good agreement with literature data for ionic liquid/water systems. Analysis of oscillations of individual C-H and O-H bonds has shown correlations between vibrational frequencies and hydrogen bonds formed by an EMIM cation or water molecule and has indicated that the changes in the IR spectrum result from the decreased number of water-water hydrogen bonds in the mixture. The tests of DFTB methodology with tailored parameterizations have yielded reasonably good description of the IR spectrum of bulk water, whereas available parameterizations have failed in satisfactory reproduction of the IR spectrum of EMIM-TFSI/water mixtures in the region above 3000 cm-1.

Tetrakis(pentafluoroethyl)gallate, [Ga(C2 F5 )4 ]- , Ionic Liquids.

We synthesized new imidazolium‐based tunable aryl alkyl ionic liquids (TAAILs) with the weakly coordinating tetrakis(pentafluoroethyl)gallate anion, [Ga(C2F5)4]−. Phenyl and phenyl derivatives (2‐Me, 4‐OMe, 2,4‐F) were combined with varying alkyl chain lengths at the imidazolium core leading to TAAILs, which were investigated with regard to their viscosity, conductivity, and electrochemical window and compared to EMIM and BMIM standard cations. Remarkable low viscosities of 29 cP at 25 °C for [BMIM][Ga(C2F5)4] were achieved. However, the EMIM and BMIM gallates show electrochemical instability, releasing pentafluoroethane at a voltage of 1.5 V. The 2‐Me‐substituted gallate‐TAAILs slowly decompose over several weeks, whereas all other gallate‐TAAILs showed no decomposition at all. With electrochemical windows of up to 5.15 V and low viscosities in a range of 66–162 cP, the gallate‐TAAILs are promising candidates as electrolytes in electrochemical applications.

Molecular Dynamics of PEDOT:PSS Treated with Ionic Liquids. Origin of Anion Dependence Leading to Cation Design Principles.

Conductivity enhancement of PEDOT:PSS via the morphological change of PEDOT-rich domains has been achieved by introducing a 1-ethyl-3-methylimidazolium (EMIM)-based ionic liquid (IL) into its aqueous solution, and the degree of such change varies drastically with the anion coupled to the EMIM cation constituting the IL. We carry out a series of molecular dynamics simulations on various simple model systems for the extremely complex mixtures of PEDOT:PSS and EMIM:X IL in water, varying the anion X, the IL concentration, the oligomer model of PEDOT:PSS, and the size of the model systems. The common characteristic found in all simulations is that although planar hydrophobic anions X are the most efficient for ion exchange between PEDOT:PSS and EMIM:X, they tend to bring together planar EMIM cations to PEDOT-rich domains, disrupting PEDOT π-stacks with PEDOT-X-EMIM intercalating layers. Nonplanar hydrophobic anions, which leave most of EMIM cations in water, are efficient for both ion exchange and the formation of extended PEDOT π-stacks, as observed in experiments. Based on such findings, we propose a design principle for new cations replacing EMIM; nonplanar hydrophilic cations combined with hydrophobic anions should improve IL efficiency for PEDOT:PSS treatment.

Understanding the dissolution of softwood lignin in ionic liquid and water mixed solvents

Lignin is the most abundant heterogeneous aromatic polymer on earth to produce a large number of value-added chemicals. Besides, the separation of lignin from the lignocellulosic biomass is essential for cellulosic biofuel production. For the first time, we report a cosolvent-based approach to understand the dissolution of lignin with 61 guaiacyl subunits at the molecular level. Atomistic molecular dynamics simulations of the lignin were performed in 0%, 20%, 50%, 80%, and 100% 1-Ethyl-3-Methylimidazolium Acetate (EmimOAc) systems. The lignin structure was significantly destabilized in both 50%, and 80% EmimOAc cosolvents, and pure EmimOAc systems leading to the breakdown of intrachain hydrogen bonds. Lignin-OAc and lignin-water hydrogen bonds were formed with increasing EmimOAc concentration, signifying the dissolution process. The OAc anions mostly solvated the alkyl chains and hydroxy groups of lignin. Besides, the imidazolium head of Emim cations contributed to solvation of methoxy groups and hydroxy groups, whereas ethyl tail interacted with the benzene ring of guaiacyl subunits. Effective dissolution was obtained in both the 50% and 80% EmimOAc cosolvent systems. Overall, our study presents a molecular view of the lignin dissolution focusing on the role of both cation and anion, which will help to design efficient cosolvent-based methods for lignin dissolution.

Understanding the conformational change and inhibition of hyperthermophilic GH10 xylanase in ionic liquid

Xylan is an abundant hemicellulosic feedstock of pentose sugars present in the Lignocellulose biomass, offering massive potential for the generation of biofuel and numerous value-added by-products. The extraction of xylan is a major challenge due to the typical organization of cellulose, hemicellulose and lignin. Ionic Liquid (IL) is a promising solvent for the deconstruction of the complex lignocellulosic structure. However, the residual IL present in the pretreated xylan significantly affects xylanase activity during the hydrolysis. Thus, a molecular understanding focusing on the IL-xylanase interaction needs to be explored for developing IL tolerant xylanases for efficient xylan hydrolysis. In this study, atomistic molecular dynamics (MD) simulations were performed to investigate the IL tolerance of hyperthermophilic GH10B xylanase from Thermotoga maritima (TmXYN10B) in both aqueous and water/1-Ethyl-3-methylimidazolium acetate (EmimAc) binary solvent systems. The enzyme was stable in all solvents at high temperature (363 K). However, the opening and closing motions of the xylanase were lost in high EmimAc concentration. Besides, the formation of a considerable number of hydrogen bonds between acetate anion and amino acids at the enzyme surface might change its native motion in high EmimAc system. The IL induced conformational change was charecterized by constructing Protein Structure Network (PSN) on each snapshot from the MD simulation trajectory. Here we captured the enzyme conformational change by identifying disjoint cliques and communities at the active site in high EmimAc concentration. Furthermore, Emim cations populated the active site with higher binding occupancy and suggested to inhibit the enzymatic hydrolysis. Finally, this study provides a theoretical understanding of the reduced activity of the TmXYN10B xylanase in IL, which can pave the path for engineering xylanases for biofuel production.

Ionothermal Synthesis of Uranyl Vanadate Nanoshell Heteropolyoxometalates.

Two uranyl vanadate heteropolyoxometalates (h-POMs) have been synthesized by ionothermal methods using the ionic liquid 1-ethyl-3-methylimidazolium diethyl phosphate (EMIm-Et2PO4). The hybrid actinide-transition metal shell structures have cores of (UO2)8(V6O22) and (UO2)6(V3O12), which we designate as {U8V6} and {U6V3}, respectively. The diethyl phosphate anions of the ionic liquids in some cases terminate the core structures to form actinyl oxide clusters, and in other cases the diethyl phosphate oxyanions link these cluster cores into extended structures. Three compounds exist for the {U8V6} cluster core: {U8V6}-monomer, {U8V6}-dimer, and {U8V6}-chain. Tungsten atoms can partially substitute for vanadium in the {U6V3} cluster, which results in a chain-based structure designated as {U6V3}-W. Each of these compounds contains charge-balancing EMIm cations from the ionic liquid. These compounds were characterized crystallographically, spectroscopically, and by mass spectrometry.

C–H···O interaction between cation and anion in amino acid-based ionic liquids—A DFT study in gas and solvent phase

The interaction between anions and cations within amino acid-based ionic liquids (AAILs) are studied in the gas phase and in three different solvents (DMSO, water, and formamide). Structural and topological analyses of ion pairs signify that they interact via C–H···O hydrogen bond. In gas and solvent phase, the aliphatic amino acids (anions) interact strongly with EMIM (1-ethyl-3-methylimidazolium) and BMIM (1-butyl-3-methylimidazolium) cations. Further, the interaction between amino acid and EMIM cation is stronger due to large charge transfer from the electronegative oxygen atoms (carbonyl group) of the amino acids to the C–H bond of the imidazole ring. All the C-H···O bonds observed between the ions are red shifted and strong due to large interaction energy. The major contribution to the interaction energy is from electrostatic and orbital energies. The implicit solvents tend to increase the H···O distance of the AAILs. The increase in the chain length of cations irrespective of phase meagerly decreases the interaction between the ions. From the solvation energy, the reaction between solvents and AAILs are exothermic. AAILs possess higher solvation energy in DMSO. Overall, ionic liquids are highly stable in the gas phase and moderately stable in the solvents due to C-H···O bonds.

Association of Nucleobases in Hydrated Ionic Liquid from Biased Molecular Dynamics Simulations.

We employed metadynamics-based classical molecular dynamics simulations to methylated adenine-thymine (mA-mT) and guanine-cytosine (mG-mC) base pairs to see favorable conformations in various concentrations of hydrated 1-ethyl, 3-methyl imidazolium acetate. We investigated various stacked and hydrogen-bonded conformations of association of base pairs through appropriately chosen collective variables. Stacked conformations more favored in water for both base pairs, whereas Watson-Crick (WC) hydrogen-bonding conformations are favored in pure and hydrated ionic liquids (ILs) except for 0.75 mol fraction IL. We observe that EMIm cations surround the base pairs in WC conformations creating a kind of hydrophobic cavity and protect the hydrogen bonds between base pairs. However, the five-membered heteroaromatic rings of cations stack with the nucleobases in the cation-base-cation (π-π-π) model, which resembles the base-base-base stacking in a DNA duplex. Interestingly, from additional simulations of 0.5 mol fraction hydrated choline dihydrogen phosphate IL, we observe that the stacked conformations become more favored than the WC conformation due to the absence of π-bonds in cations. The calculated values of relative solubility of base pairs in pure and hydrated ionic liquids compared to those in pure water correlate well with the free energy values of WC and stacked conformations.

Ionothermal synthesis, crystal structure and properties of one organic–inorganic compound based on basket-like {Sr⊂P6Mo18O73} cage

One organic–inorganic hybrid phosphomolybdate compound H(EMIM)3[{Cu(phen)2}{Sr⊂P6Mo18O73}]·H2O (1) (EMIM = 1-ethyl-3-methylimidazolium, phen = 1,10-phenanthroline) has been synthesized and structurally characterized. Compound 1 represents the first example of basket-like {P6Mo18O73} POMs synthesized by ionothermal method, and exhibits a novel structure of the fully oxidized heteropolyanion supported by one {Cu(phen)2}2+ fragment with EMIM cations as charge balancing species. Compound 1 shows an obvious photocatalytic activity for degradation of rhodamine B (RhB). In addition, compound 1 exhibits good multiple electrocatalytic properties toward the redox of H2O2, NaNO2, ascorbic acid (AA) and dopamine hydrochloride (DH), respectively.

Anion Bridging-Induced Structural Transformation of Cellulose Dissolved in Ionic Liquid

We performed structural investigations of cellulose mixed with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) in the entire concentration range (0-100 mol %) by wide-angle X-ray scattering with the aid of quantum chemical calculations and 13C solid-state NMR spectroscopy. We particularly focused on a highly concentrated region (≥30 mol %), which has previously been overlooked. At concentrations of 15-30 mol %, a periodic peak corresponding to cellulose chain alignment emerged; this is associated with a lyotropic cholesteric liquid-crystalline phase. At concentrations of ≥30 mol %, the structure is transformed into ordered layers where OAc anions and Emim cations intercalate. This transformation is found to be driven by a change in the interaction between the IL anions and the OH groups of cellulose. At low concentrations, the anion mainly interacts with the OH group of cellulose in a 1:1 ratio, as previously reported; at high concentrations, the anions bridge the OH groups of two cellulose chains.

Unexpected Dimeric Spiro‐Borate Complexes from Lewis‐Acid Induced Transformation of Oxalatoborates

Oxalatoborates were transformed into dimeric spiro‐borate complexes by abstraction of oxalate ligands by Lewis acidic lanthanide trichlorides. Oxalatoborates with different anions and cations were investigated containing either bis‐oxalatoborate or catecholato‐oxalatoborate anions and lithium as well as EMIM (1‐ethyl‐3‐methyl‐imidazolium) and BMIM cations (1‐n‐butyl‐3‐methyl‐imidazolium) from the respective ionic liquids (ILs). Depending on the amount of oxalate groups and the different cations, the oxalate groups are partly or fully abstracted and transferred to the lanthanides. The reaction of anhydrous PrCl3 with Li[B(C6H4O2)(C2O4)] (lithium catecholato‐oxalatoborate = Li[Catbox]) in pyridine (py) led to a conversion of the borate anion to the complex [B2O(C6H4O2)(py)4][PrCl5(py)] (1). The use of the ILs [EMIM][Catbox] and [BMIM][Catbox] indicates complete transfer of the oxalate groups to the lanthanide ions in reactions with lanthanide chlorides and nitrates yielding the well‐known lanthanide oxalates Ln2(C2O4)3·10H2O (Ln = La, Eu). In contrast, the reaction of anhydrous YCl3 with Li[B(C2O4)2] (lithium bis‐oxalatoborate = Li[BOB]) in N,N‐dimethylformamide (dmf) results in the formation of [B2O(C2O4)2(dmf)2] (2). Transfer of one oxalate group per boron onto the yttrium ion is revealed by the formation of the one‐dimensional coordination polymer ∞1[LiYCl2(C2O4)(dmf)3] (3) as additional product. The products were characterized by single‐crystal X‐ray diffraction as well as powder X‐ray diffraction, IR spectroscopy and elemental analysis.

The Effect of Pressure on the Role of Tfsa Conformational Exchange in Ionic Liquids

A comprehensive study of multi-nuclear (1H, 2H, and 19F) magnetic resonance self-diffusion coefficients (D) and spin-lattice relaxation times (T1) was done as functions of both temperature and pressure on selectively deuterated 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMIM TFSA) ionic liquid isotopologues and related ionic liquids. While variable temperature studies provided useful insight, pressure dependent studies were more elucidating as discussed below. First, stronger electric field gradients were indicated in the alkyl chain region compared to the imidazolium ring of EMIM TFSA as determined from variable temperature 2H T1. Second and most significantly, variable pressure measurements of the EMIM and TFSA diffusion revealed independent motions for the cations and anions, with that of the TFSA anions being slowed much more by increasing pressure than for the EMIM cations. Activation volumes were determined from the pressure dependent D data and values of 28.8 ± 2.5 cm3/mol and 14.6 ± 1.3 cm3/mol were obtained for TFSA and EMIM respectively. Typically, smaller activation volumes support less restriction in motion. One possible explanation for this difference in behavior between EMIM and TFSA is that increasing pressure limits the conformational mobility of the TFSA. Third, variable pressure 2H T1 data shows two T1 regimes, for the MD3 and D2 isotopologues between 0.1-100 and 100-250 MPa respectively. These two regimes could represent dissimilar arrangements for the EMIM cation. Activation volumes determined from the pressure dependent 2H T1 data were 21 and 25 (0-100 MPa) and 11 and 12 (100-250 MPa) cm3/mol for the MD3 and D2 isotopologues, respectively. These and other details will be discussed.

Do TFSA Anions Slither? Pressure Exposes the Role of TFSA Conformational Exchange in Self-Diffusion.

Multinuclear ((1)H, (2)H, and (19)F) magnetic resonance spectroscopy techniques as functions of temperature and pressure were applied to the study of selectively deuterated 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMIM TFSA) ionic liquid isotopologues and related ionic liquids. For EMIM TFSA, temperature-dependent (2)H T1 data indicate stronger electric field gradients in the alkyl chain region compared to the imidazolium ring. Most significantly, the pressure dependences of the EMIM and TFSA self-diffusion coefficients revealed that the displacements of the cations and anions are independent, with diffusion of the TFSA anions being slowed much more by increasing pressure than for the EMIM cations, as shown by their respective activation volumes (28.8 ± 2.5 cm(3)/mol for TFSA vs 14.6 ± 1.3 cm(3)/mol for EMIM). Increasing pressure may lower the mobility of the TFSA anion by hindering its interconversion between trans and cis conformers, a process that is coupled to diffusion according to published molecular dynamics simulations. Measured activation volumes (ΔV(‡)) for ion self-diffusion in EMIM bis(fluoromethylsulfonyl)amide and EMIM tetrafluoroborate support this hypothesis. In addition, (2)H T1 data suggest increased ordering with increasing pressure, with two T1 regimes observed for the MD3 and D2 isotopologues between 0.1-100 and 100-250 MPa, respectively. The activation volumes for T1 were 21 and 25 cm(3)/mol (0-100 MPa) and 11 and 12 cm(3)/mol (100-250 MPa) for the MD3 and D2 isotopologues, respectively.

Neutron Powder Diffraction study of the Magnetic Ionic Liquid Emim[FeCL4] and its deuterated phase

A magnetic ionic liquid comprising 1-ethyl-3 methylimidazolium (Emim) cations and tetraclhoroferrate(III) (FeCl4) anions and its deuterated phase were synthetized and characterized magnetically. In both materials, the low temperature dependence of the magnetic susceptibility presents a maximum (around 4 K) related to an antiferromagnetic ordering, but the ordering temperatures are slightly shifted and the curves display different shapes. In addition, the magnetization of the deuterated phase tends to saturate at higher values than that corresponding to the non-deuterated analogue. A comparison of the neutron diffraction patterns above and below the magnetic transition clearly shows that the crystal and magnetic structures of these materials are different. Therefore, the present findings clearly prove that the magnetic exchange interactions that induce three-dimensional magnetic ordering are modified after the deuteration process.

Effect of Pressure on the Deuteron Spin-Lattice Relaxation Times and the Self-Diffusion Coefficient in Ionic Liquids

Ionic liquids (ILs) are of considerable interest for their physical properties: negligible vapor pressure, thermal and electrochemical stability, and high ionic conductivity, thus making them attractive for applications in radioactive material handling, batteries, capacitors, and electrochemical solar cells. A large variation of physical properties of ILs results from a corresponding variation of the structure and length of the cation sidechains and choice of anion, thus allowing tunability of properties for selected applications. In this context, there is much interest in the molecular motions that control transport properties and chemical processes. In this work we present investigations of a set of ILs based on the EMIM and BMIM cations and TFSI anion, in which the cation sidechains were partially deuterated. The 2H spin-lattice relaxation times (T1) have been measured at 47 MHz in the temperature range from 240 to 370 K (Graph 1) and under hydrostatic pressure from ambient to 250 Mpa. (Graph 2) with the deuteron T1 providing a particularly sensitive probe of alkyl side-chain reorientation. Additionally the self-diffusion coefficient (D) of both cation (using 1H NMR) and anion (using 19F NMR) were conducted as a function of temperature and Pressure (Graph 3). The Arrhenius plots of T1 exhibit T1 minima, and analyzed assuming an exponential decaying correlation function (BPP model). The high pressure T1 and D measurements were carried out to determine the activation volume of alkyl chain motion. Longer alkyl chain of BMIM exhibits a pressure invariance of the relaxation time after 80 Mpa possibly related to interactions between alkyl groups on adjacent cations. Hunter College acknowledges the U.S. Office of Naval Research for supporting the NMR portion of this project. The work at BNL was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences under contract # DE-AC02-98CH10886.

Ionic liquids from the bottom up: Local assembly motifs in [EMIM][BF4] through cryogenic ion spectroscopy

To clarify the intramolecular distortions exhibited by the complementary ions in the archetypal ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], we report the vibrational spectra of the isolated ionic constituents and small aggregates cooled to about 10 K. Deuteration of bare EMIM(+) at the C(2) position, the putative hydrogen bond donating group, establishes that the observed bulk red shift is too small (<10 cm(-1)) for hydrogen bonding to be a dominant structural feature. We then analyze how the vibrational patterns evolve with increasing size to identify the spectral signatures of well-defined structural motifs in the growing assembly. Surprisingly, the main features of the bulk spectrum are already developed in the cluster with a single BF4 (-) anion sandwiched between just two EMIM(+) cations. We suggest that this local motif, while not strongly hydrogen bonded, nonetheless induces considerable intensity in the C(2)H stretches and is a robust feature in the local molecular structure of the liquid.

Bis(1-ethyl-3-methylimidazolium) 3,6-diselanylidene-1,2,4,5-tetraselena-3,6-diphosphacyclohexane-3,6-diselenolate

In the title compound, 2C6H11N2 +·P2Se8 2− or [EMIM]2P2Se8 (EMIM = 1-ethyl-3-methyl­imidazolium), the anions, located about inversion centers between EMIM cations, exhibit a cyclo­hexane-like chair conformation. The cations are found in columns along the a axis, with centroid–centroid distances of 3.8399 (3) and 4.7530 (2) Å. The observed P—Se distances and Se—P—Se angles agree with other salts of this anion.

Adsorbed and near surface structure of ionic liquids at a solid interface

The structure of solid-ionic liquid (IL) interfaces has been characterised with unprecedented clarity by employing a range of atomic force microscopy (AFM) imaging techniques and tip pressures appropriate for the system under study. Soft contact and amplitude-modulation (AM) AFM imaging have been used to elucidate the lateral structure of ILs adsorbed onto mica, and in the near surface ion layers. Data is presented for ethylammonium nitrate (EAN) and 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)imide (EMIm TFSI). Whereas EAN is a protic IL that forms a nanostructured sponge phase in the bulk, EMIm TFSI is aprotic and has weak (or absent) bulk association structure. Comparison of results obtained for the two liquids elucidates how the strength of bulk liquid morphology effects lateral organisation at the surface, and any effect of IL class, i.e. protic versus aprotic. Imaging reveals EAN self assembles at the solid surface in a worm-like morphology, whereas EMIm cations adsorb in a more isolated fashion, but still in rows templated by the mica surface. To the authors' knowledge, the wormlike structures present at the EAN-mica interface are the smallest self-assembled aggregates ever imaged on a solid surface.

Hildebrand solubility parameters of ionic liquids: Effects of ionic liquid type, temperature and DMA fraction in ionic liquid

The Hildebrand solubility parameters of 10 ionic liquids were investigated using the approach of intrinsic viscosity. Effects of dimethylacetamide (DMA) fraction in ionic liquids and dissolution temperature on the Hildebrand solubility parameter were also studied. Moreover, cohesive energy density, molar internal energy and enthalpy of dissolution were calculated. Cation and anion of an ionic liquid shows a significant influence on the solubility parameter. The values of ionic liquids containing BMIM cations are in the following order: [PF6]>[Tf2N]>[Cl], while those of ionic liquids containing EMIM cations are in the order: [BF4]>[DEPO4]>[AC]. Ionic liquid containing HOEMIM exerts the highest solubility parameter than that containing MBPYRRO or BMIM. Considering effect of varying DMA fraction, the Hildebrand solubility parameters of the mixtures do not correspond to the mixing rule. Their values tend to be closer to those of the ionic liquids than that of DMA for 40–90vol% DMA added in the ionic liquids (1-Ethyl-3-methylimidazolium acetate (EMIM-AC) and 1-Butyl-3-methylimidazolium chloride (BMIM-Cl)). With increasing temperature from 25 to 60°C, decreases of Hildebrand solubility parameters from 25.2 to 24.7 for EMIM-AC and the mixture of EMIM-AC/DMA (60–40v/v) were obtained. The cohesive energy densities of ionic liquids at the different conditions are proportional directly with the Hildebrand solubility parameter. The molar internal energy and the enthalpy of dissolution decrease with increasing DMA fraction in ionic liquids, while they are almost constant or show slight decreases with the increase of dissolution temperature for EMIM-AC and the mixture of EMIM-AC/DMA (60–40v/v), respectively.