Effect of additives on the surface active and morphological features of 1-octyl-3-methylimidazolium halide aggregates in aqueous media

The influence of two salts as additives namely sodium chloride and sodium sulphate and a nonelectrolyte, 2-butoxyethanol on surface chemical and aggregation characteristics of ionic liquids (IL) of 1-octyl-3-methylimidazolium chloride, [C₈mim][Cl], 1-octyl-3-methylimidazolium bromide, [C₈mim][Br], and 1-octyl-3-methylimidazolium iodide, [C₈mim][I] in aqueous media were monitored through surface tension and small angle neutron scattering measurements. The addition of salts drastically decreased the critical aggregation concentration (CAC) and increased the area per adsorbed IL molecule. The co-ions of salts modify the surface of IL molecules and aggregates through various interactions such as charge neutralization, specific interactions and dehydration The results obtained by analyzing the SANS curves in the whole Q range showed that the oblate ellipsoidal shape of the aggregates of ionic liquids is un-altered upon the addition of additives. However the additives facilitate the growth of the aggregates in to microstructures with cubic packing at high salt concentrations.     

Structural studies of the phase, aggregation and surface behaviour of 1-alkyl-3-methylimidazolium halide + water mixtures

The surface, phase and aggregation behaviour of mixtures of 1-alkyl-3-methylimidazolium halide, [C(n)mim]X, where n is the alkyl chain length, with water has been explored using a variety of methods. Critical micelle concentrations (cmc) and micelle structures have been determined for aqueous [C(n)mim]Br solutions for n=2, 4, 6, 8, and 10. Small-angle neutron scattering (SANS) measurements reveal that for the n=8 and 10 systems, at concentrations just above the cmc, small near-spherical aggregates exist, which, after initial growth, possess core radii (aggregation numbers) at intermediate concentrations of 10.5+/-0.5 Angstrom (22+/-2) and 13.2+/-0.5 Angstrom (40+/-3), respectively, for n=8 and n=10. Towards higher concentrations, the aggregates appear to grow, with the aggregates in the [C(10)mim]Br system becoming increasingly elongated (prolate) with increasing concentration. No evident aggregates are formed in the systems with n=2 and 4. In the n=6 system, it appears that oblate aggregates with radius approximately 9 Angstrom form at the cmc and that the radius increases with increasing concentration. For longer alkyl chain lengths, at high concentrations lyotropic mesophases form in some systems. The mesophase region for the [C(8)mim]Cl system has been explored across the composition range using X-ray diffraction and (2)H NMR spectroscopy. Both techniques suggest that a major hexagonal phase with lattice parameter of 29.5+/-0.5 Angstrom coexists with a minor lamellar phase (23.5+/-0.3 Angstrom) or possibly a second hexagonal phase (27.1+/-0.4 Angstrom). The area per adsorbed molecule at the surface of [C(8)mim]Br solutions has been measured as a function of concentration using neutron reflectometry. A minimum in the area per molecule behaviour is coincident with a minimum identified in the surface tension isotherm occurring close to the cmc. The data suggest depletion of [C(8)mim]Br from the surface region occurs at concentrations immediately above the cmc.     

Aggregation behavior of ionic liquids in aqueous solutions: effect of alkyl chain length, cations, and anions

Self aggregation of the ionic liquids, 1-butyl-3-methylimidazolium chloride [C4mim][Cl], 3-methyl-1-octylimidazolium chloride [C8mim][Cl], 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim][BF4], N-butyl-3-methylpyridinium chloride [C4mpy][Cl], in aqueous solution has been investigated through 1H nuclear magnetic resonance (NMR) and steady-state fluorescence spectroscopy. Aggregation properties were determined by application of mass action theory to the concentration dependence of 1H NMR chemical shifts. Aggregation properties showed fairly good agreement with the previously reported results obtained from small angle neutron scattering, conductivity, and surface tension measurements. A detailed analysis of chemical shifts of water and various protons in ILs has been employed to probe the aggregate structure. Fluorescence spectroscopy provided important information about the critical aggregation concentration (cac) and the microenvironment of the aggregates. We could also observe a break point quite consistent with that of 1H NMR and fluorescence spectroscopy at cac from the concentration dependence of refractive index measurements. Standard free energies of aggregation DeltaGom of various ILs derived using the refractive index/concentration profiles were found comparable to those of classical ionic surfactants.     

Effect of imidazolium-based ionic liquids on the aggregation behavior of twin-tailed cationic gemini surfactant in aqueous solution

Micellization behavior of the twin-tailed surfactants can be modulated by the addition of various modifiers. Ionic liquids (ILs) are one of them and are documented here. The beauty of these environmentally benign neoteric molecules lies in their structural versatility. Here, we have investigated the effect of three ILs: 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]), 1-hexyl-3-methylimidazolium bromide ([C₆mim][Br]), and 1-octyl-3-methylimidazolium bromide ([C₈mim][Br]) on the aggregation and surface adsorption behavior of cationic gemini surfactant, bis(hexadecyldimethyl ammonium)propane dibromide (16-3-16) through experimentally measured electrical conductivities, surface tensions, and by spectral methods (UV-vis absorbance and fluorescence measurements). The main focus of the study is to observe the effect of added ILs on the critical micelle concentration (cmc), various surface parameters, aggregation number, and size of the aggregates of gemini surfactant. The results show that the more hydrophobic ILs, that is, [C₆mim][Br] and [C₈mim][Br] behave as electrolyte at lower concentration and cosurfactant at higher concentration, whereas moderately hydrophobic IL [C₄mim][Br] acts as an electrolyte at all concentration ranges studied. The modulating effects of ILs were also compared with conventional electrolyte (NaBr) at similar conditions.     

Effect of the aliphatic chain length on electrical double layer formation at the liquid/vacuum interface in the [C(n)mim][BF4] ionic liquid series

Neutral impact collision ion scattering spectroscopy (NICISS) was used to determine the surface structure of three ionic liquids, 1-hexyl-3-methylimidazolium [C(6)mim], 1-octyl-3-methylimidazolium [C(8)mim], 1-decyl-3-methylimidazolium [C(10)mim] tetrafluoroborates [BF(4)]. Concentration depth profiles of the elements in an ionic liquid (IL) homologous series with a common anion were obtained. We show that separation between the oppositely charged ions is seen for all three ionic liquids, resulting in an electrical double layer formation. The surface charge shifts from more positive to more negative with increasing aliphatic chain length.     

Surface active and aggregation behavior of methylimidazolium-based ionic liquids of type [Cnmim] [X], n?=?4, 6, 8 and [X]?=?Cl?, Br?, and I? in water

The surface active and aggregation behavior of ionic liquids of type [C _n mim][X] (1-alkyl-3-methylimidazolium (mim) halides), where n = 4, 6, 8 and [X] = Cl⁻, Br⁻ and I⁻ was investigated by using three techniques: surface tension, ¹H nuclear magnetic resonance (NMR) spectroscopy, small-angle neutron scattering (SANS). A series of parameters including critical aggregation concentrations (CAC), surface active parameters and thermodynamic parameters of aggregation were calculated. The ¹H NMR chemical shifts and SANS measurements reveal no evidence of aggregates for the short-chain 1-butylmim halides in water and however small oblate ellipsoidal shaped aggregates are formed by ionic liquids with 1-hexyl and 1-octyl chains. Analysis of SANS data analysis at higher concentrations of [C₈mim][Cl] showed that the microstructures consist of cubically packed molecules probably through π–π and hydrogen bond interactions.     

Separation of ternary systems of hydrophilic ionic liquid with miscible organic compounds by RPLC with refractive index detection

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated. The optimum mobile phase for the system [C(8)mim]Cl-ethyl acetate-EtOH, [C(4)mim]Cl-ethyl acetate-EtOH, [Amim]Br-ethyl acetate-EtOH and [Amim]Cl-ethyl acetate-EtOH was methanol/water (60:40, v/v), and methanol/water (70:30, v/v) for [C(6)mim]Cl-ethyl acetate-EtOH. Under optimum mobile phase conditions for each system, the RSD of the retention time ranged from 0.02 to 0.04%, and the RSDs of the peak area percent ranged from 0.23 to 1.85%, which showed good reproducibility of the RPLC-RI method. The RPLC-RI method can determine IL, ethyl acetate, and EtOH simultaneously in 5 min, and the analytes, especially IL, can be eluted completely. The results show that the RPLC-RI method can be used to separate and determine ILs in mixtures with organic compounds simultaneously and quantitatively.     

Aggregation of ionic liquids [C(n)mim]Br (n = 4, 6, 8, 10, 12) in D2O: a NMR study

Aqueous solutions of five ionic liquids (ILs) of the 1-n-alkyl-3-methylimidazolium bromide family, [C(n)mim]Br (n = 4, 6, 8, 10, 12), were investigated by NMR measurements at 298.2 K as a function of IL concentrations. Critical aggregation concentrations and aggregation numbers of these ILs were determined by 1H NMR except for [C4mim]Br in D2O. The effects of the alkyl chain length of the cations were examined on the aggregation behavior of the ILs. 1H NMR data of the solvent D2O were used to investigate the hydration of the ILs in D2O, and it was found that the ionic hydration and the cation-anion association or aggregation of the ILs offset each other. The microenvironment of different protons of cations of the ILs in the aggregates was probed by determining the spin-lattice relaxation rate (1/T1). It is suggested that the imidazolium rings in the aggregates are exposed to water and that the molecular motion of the aggregates is more restricted than that of the monomers of the ILs. Furthermore, a stair-like microscopic aggregation structure is suggested for the [C(n)mim]Br/D2O (n = 6, 8, 10) systems from 2-D 1H-1H NOESY measurements.     

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(III) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim][PF(6)]/[Tf(2)N]-based extraction system without increasing the loss of [C(n)mim](+).     

Ionic liquid salt bridge in dilute aqueous solutions.

A new type of salt bridge composed of a hydrophobic room-temperature ionic liquid, recently proposed (T. Kakiuchi and T. Yoshimatsu, Bull. Chem. Soc. Jpn., 2006, 79, 1017), has been shown to be satisfactorily usable in dilute aqueous solutions of submillimolar range. A stable phase-boundary potential has been demonstrated between an ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(8)mim+][C(1)C(1)N-), and an aqueous KCl solution of submillimolar level, which is lower than the solubility of [C(8)mim+][C(1)C(1)N-] in water, 1.6 mmol dm(-3) at 25 degrees C. The phase-boundary potential between [C(8)mim+][C(1)C(1)N-] and water is maintained constant over more than four orders of magnitude change in the concentration of an aqueous electrolyte solution. The ionic-liquid salt bridge is a superior alternative to salt bridges based on equitransferent electrolytes in practical applications, particularly, the potentiometry of samples of low ionic strengths, such as potentiometric pH measurements of rainwater.     

Conductivities, volumes, fluorescence, and aggregation behavior of ionic liquids [C4mim][BF4] and [C(n)mim]Br (n = 4, 6, 8, 10, 12) in aqueous solutions

Densities, conductivities, and polarity indexes of pyrene for aqueous solutions of a series of ionic liquids [C(n)mim]Br (n = 4, 6, 8, 10, 12) and [C4mim][BF4] have been determined at 298.15 K as a function of ionic liquid concentrations. It was shown that possible aggregation appeared for the ionic liquids in aqueous solutions except for [C4mim]Br. The critical aggregation concentration (CAC) of the ionic liquids, the ionization degree of aggregates (beta), the standard Gibbs energy of aggregation (Delta G(m)(o)), the limiting molar conductivity (Lambda(m)(o)), and the standard partial molar volume (V(m)(o)) for the ionic liquids were derived from the experimental data. The dependence of the CAC, Delta G(m)(o), Lambda(m)(o), and V(m)(o) on the length of the alkyl chain of the cations was examined. It was further suggested from volumetric data that a micelle was formed for [C8mim]Br, [C10mim]Br, and [C12mim]Br in aqueous solutions. Their apparent molar volumes at the critical micelle concentration (V Phi,CMC), apparent molar volumes in the micelle phase (V(Phi)(mic)), and the change of their apparent molar volume upon micellization (Delta V Phi,m) were calculated by application of the pseudophase model of micellization. In addition, the average aggregation number of [C(n)mim]Br (n = 8, 10, 12) has been determined by the steady-state fluorescence quenching technique, and predicted from a simple geometrical mode. It is found that the experimental values are in good agreement with the predicted ones.     

Effects of alcohols and counterions on the phase behavior of 1-octyl-3-methylimidazolium chloride aqueous solution

Phase behavior of ternary systems involving 1-octyl-3-methylimidazolium chloride ([C8mim]Cl), water, and different alcohols (1-hexanol, 1-octanol, 1-decanol, and 1-dodecanol) is investigated at 25 degrees C. With the use of polarized optical microscopy and small-angle X-ray scattering techniques, lyotropic lamellar phases (Lalpha) are identified in all systems, the formation of which is considered as a synergetic result of the hydrophobic force and the hydrogen-bonded network comprising an imidazolium ring, Cl-, water, and alcohols. In these Lalpha phases, alcohol molecules play important roles not only because they could partly penetrate into the palisade layer with their hydroxyl groups extruded to form the network at the aggregate interface, but also because they could partly locate themselves in the interior of the hydrophobic bilayers to twist with the alkyl chains of [C8mim]Cl. Influencing factors such as the carbon chain length and content of different alcohols on these Lalpha phases are discussed. With comparison to analogous ternary systems of [C8mim]BF4 and [C8mim]PF6, it is found that the strong interaction between counterions and alcohols favors the appearance of ordered assemblies.     

Aggregation behavior of a model ionic liquid surfactant in monosaccharide + water solutions

Alkylimidazolium salts are a very important class of ionic liquids (ILs). The ILs containing long alkyl chains are a kind of model surfactants. In this paper, the aggregation behavior of 1-decyl-3-methylimidazolium chloride ([C(10)mim]Cl) was investigated for the first time in aqueous monosaccharide (glucose, galactose, xylose and arabinose) solutions by conductivity, fluorescence, NMR and dynamic light scattering (DLS). Thus a series of physico-chemical parameters for the aggregation of [C(10)mim]Cl-the critical aggregation concentration (CAC), ionization degree of the aggregates (α), the standard Gibbs energy of aggregation (ΔG(m)(0)), and the aggregation number (N) were derived from the experimental data. The results show that addition of small amounts of monosaccharides in aqueous solution can cause a variation in aggregation properties of the IL. The CAC values decrease with increasing molality of monosaccharides. In particular for different kinds of monosaccharides, we found that the CAC values are in the order: glucose>galactose (hexoses), xylose>arabinose (pentoses); xylose>glucose (1e2e3e4e), arabinose>galactoses (1e2e3e4a). These trends may be attributed to the slight difference in the stereo-structure of monosaccharide molecules. Finally a mechanism for the interaction of these monosaccharides with [C(10)mim]Cl was proposed.     

Study on the Conductivities of Pure and Aqueous Bromide-Based Ionic Liquids at Different Temperatures

Electrical conductivities were measured for the pure ionic liquids [C₆mim][Br] (1-hexyl-3-methylimidazolium bromide) and [C₈mim][Br] (1-octyl-3-methylimidazolium bromide) at 0.1 MPa from 293.15 to 333.15 K. Conductivity measurements were also made for the binary water + [C₆mim][Br] and water + [C₈mim][Br] systems and their ternary water + [C₆mim][Br] + [C₈mim][Br] system at 0.1 MPa and 293.15, 298.15, and 303.15 K. The conductivity data of the pure ionic liquids were correlated by the VFT (Vogel-Tamman-Fulcher) equation, and the fitting parameters and mean absolute deviations were determined. New explanations are presented for the molality-dependent behavior of the conductivity of the binary water + [C₆mim][Br] and water + [C₈mim][Br] systems. The generalized Young’s rule and the semi-ideal solution theory for conductivity were used to predict the conductivities of the ternary water + [C₆mim][Br] + [C₈mim][Br] system from the conductivities of its corresponding binary water + [C₆mim][Br] and water + [C₈mim][Br] subsystems. The predictions are in good agreement with the measured values.     

Modulation of the aggregation behaviour and physicochemical properties of 1-dodecyl-3-methylimidazolium bromide in aqueous solutions by β-CD

The modulation of aggregation behaviour of ionic liquids (ILs) in aqueous media is one of the important research topics. In the present work, aggregation behaviour of 1-dodecyl-3-methylimidazolium bromide ([C₁₂mim]Br) modulated by beta-cyclodextrin (β-CD) has been investigated by using conductivity, volume, fluorescence, dynamic light scattering and transmission electron microscopy techniques. The results suggested that the addition of β-CD significantly affects the aggregation of [C₁₂mim]Br in aqueous solutions. For example, the apparent critical micelle concentration increases with the increase of β-CD concentration; the average micellar size reduced with the increasing concentration of β-CD, and the process for micelle formation of [C₁₂mim]Br in aqueous β-CD solution is driven by entropy at lower temperature, while driven by enthalpy at higher temperature. It is expected that findings in this study would shed light on the potential applications of IL in supramolecular chemistry.     

咪唑基离子液体的物理化学性质估算及预测(英文)

根据经验和半经验方程及空隙模型理论,可以估算及预测离子液体在298.15K的物理化学性质.本文讨论了离子液体的分子体积,密度,标准熵,晶格能,表面张力,等张比容,摩尔蒸发焓,空隙体积,空隙率和热膨胀系数.通过实验测得的三种离子液体1-乙基-3-甲基咪唑硫酸乙酯([C2mim][EtSO4)]),1-丁基-3-甲基咪唑硫酸辛酯([C4mim][OcSO4])和1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐([C2mim][NTf2])的密度和表面张力估算了它们的其它物理化学性质.由这三种离子液体的分子体积及等张比容预测了同系列中其它离子液体[Cnmim][EtSO4],[Cnmim][OcSO4]和[Cnmim][NTf2](n=1-6)的分子体积及等张比容,由此计算出它们的密度及表面张力.进而预测了它们的物理化学性质.将预测的离子液体[C4mim][NTf2]和[C2mim][OcSO4]的密度值与文献报导的实验值进行比较,其偏差在实验误差范围内.最后,将由Kabo经验方程计算的七个离子液体[C2mim][EtSO4]、[C4mim][OcSO4]、[C2mim][NTf2]、[C4mim][NTf2]、丁基三甲基铵双三氟甲磺酰亚胺盐([N4111][NTf2])、甲基三辛基铵双三氟甲磺酰亚胺盐([N8881][NTf2])和1-辛基-3-甲基吡啶四氟硼酸盐([m3opy][BF4])的摩尔蒸发焓与由Verevkin简单规则预测的摩尔蒸发焓进行比较,发现两者符合很好.因此,在缺乏密度和表面张力实验数据的情况下,可以用Verevkin简单规则来预测离子液体的摩尔蒸发焓.     

Comparison of physicochemical properties of new ionic liquids based on imidazolium, quaternary ammonium, and guanidinium cations

More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p-toluenesulfonate [TSA](-), dicyanoamide [DCA]-, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC]-, trifluoroacetate [TFA]-, bis(trifluoromethanesulfonyl)imide [Tf2N]-, trifluoromethanesulfonate [TfO]-, and thiocyanate [SCN]-. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid-liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made.     

Interaction of anionic dyes and cationic surfactants with ionic liquid character

The interactions of an imidazolium based ionic liquid (IL), namely 1-dodecyl-3-methylimidazolium chloride [C12 mim][Cl] with two sulfonated anionic dyes, azocarmine G and methyl orange, are studied spectrophotometrically in both acidic and basic media. ILs (with some surface active character) can interact with the above dyes and cause considerable shifts in their spectra. These interactions are then compared with some surfactant-dye interactions. Evolving factor analysis (EFA) and multivariate curve resolution-alternating least squares (MCR-ALS) are used for complete resolution of the measured spectrophotometric data. The concentration and spectral profiles of all species were calculated without any assumption of the chemical models. The spectral variation of dye solutions as a function of IL concentrations below and above the critical aggregation concentration (CAC) is analyzed using MCR-ALS as a soft-modeling technique. The ion pair formation constants between ILs and dyes were calculated using the obtained concentration profiles.     

Solvation of carbohydrates in n,n'-dialkylimidazolium ionic liquids: a multinuclear NMR spectroscopy study

The solvation of carbohydrates in N, N'-dialkylimidazolium ionic liquids (ILs) was investigated by means of 13C and 35/37Cl NMR relaxation and 1H pulsed field gradient stimulated echo (PFG-STE) diffusion measurements. Solutions of model sugars in 1- n-butyl-3-methylimidazolium chloride ([C4mim]Cl), 1-allyl-3-methylimidazolium chloride ([CC2mim]Cl), and 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) were studied to evaluate the effects of cation and anion structure on the solvation mechanism. In all cases, the changes in the relaxation times of carbon nuclei of the IL cations as a function of carbohydrate concentration are small and consistent with the variation in solution viscosities. Conversely, the 35/37Cl and 13C relaxation rates of chloride ions and acetate ion carbons, respectively, have a strong dependency on sugar content. For [C2mim][OAc], the correlation times estimated from 13C relaxation data for both ions reveal that, as the carbohydrate concentration increases, the reorientation rate of the anion decreases faster than that of the cation. Although not as marked as the variations observed in the relaxation data, similar trends were obtained from the analysis of cation and, in the case of [C2mim][OAc], anion self-diffusion coefficients of the sugar/IL systems. Our results show that the interactions between the IL cation and the solutes are nonspecific, confirm that the process is governed by the interactions between the IL anion and the carbohydrate, and, more importantly, indicate no change in the solvation mechanism regardless of the structure of the anion.     

Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Two stable nanofluids comprising of mixed valent copper(I,II) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C(4)mim][OAc], and copper(II) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl)phosphonium acetate, [P(8 8 8 12)][OAc], were synthesised in a facile one-pot reaction from solutions of copper(II) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using (13)C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc)(2) in 1-ethyl-3-methylimidazolium acetate, [C(2)mim][OAc], crystals were obtained that revealed the structure of [C(2)mim][Cu(3)(OAc)(5)(OH)(2)(H(2)O)]·H(2)O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry.