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The present study aimed to determine the cytotoxicity of 1-methyl-3-octylimidazolium bromide ([C 8 mim]Br) on the human hepatocellular carcinoma (HepG2) cells in order to elucidate the biochemical and molecular mechanism of [C 8 mim]Br-cytotoxicity. For this purpose, cell viability, oxidative stress, apoptosis, caspase activity, and apoptosis-related gene expression in HepG2 cells following [C 8 mim]Br-exposure were evaluated. The results showed that viability of HepG2 cells was decreased by [C 8 mim]Br-exposure in a concentration-dependent pattern. Moreover, biochemical assays reveal that [C 8 mim]Br-exposure can induce apoptosis, cause overproduction of reactive oxygen species (ROS), inhibit superoxide dismutase and catalase, reduce glutathione content, and increase the cellular malondialdehyde level of HepG2 cells. The transcriptions of p53 and bax were markedly up-regulated while bcl-2 was significantly down-regulated in HepG2 cells after [C 8 mim]Br-exposure, suggesting that p53 and bcl-2 family may be involved in the cytotoxicity and apoptosis of HepG2 cells caused by [C 8 mim]Br. In addition, we also found that caspase-3, caspase-8, and caspase-9 were significantly activated in HepG2 cells following [C 8 mim]Br-exposure. Our results suggest that ROS may be a key early signal of [C 8 mim]Br-induced apoptosis and caspases play a key role in the initiation and execution of apoptosis of HepG2 cells. [ABSTRACT FROM AUTHOR]

Abstract: Information on the interactions between ionic liquids and molecular solvents are essential for the understanding of the function of ionic liquids in related procedures, and excess properties are sensitive probe for these interactions. In this work, excess molar volume and excess logarithmic viscosity ((ln η)E) for the binary mixtures of 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim][BF4]) with butanone, ethyl acetate, butylamine, and tetrahydrofuran have been determined from density and viscosity measurements in the whole composition range at the temperature of 298.15K. It is found that for the studied systems, the values of are negative but those of (ln η) E are positive in the whole concentration range. The values show their minimum at the ionic liquid mole fraction of 0.3, and (ln η) E values exhibit a maximum at the same composition. The absolute values of follow the sequence: tetrahydrofuran>butanone>ethyl acetate>butylamine for the binary systems, whereas the values of (ln η) E decrease in the order: tetrahydrofuran>butylamine>ethyl acetate>butanone. The results have been analyzed through the ion–dipole interaction, the hydrogen bonding, the packing efficiency and the ion-pairs exist in the ionic liquid. [Copyright &y& Elsevier]

The apparent molar volumes (Vm,2) and relative viscosities (ηr) at T=(298.15 and 308.15) K have been obtained for glycine, dl-α-alanine, and dl-α-amino-butyric acid in aqueous sodium caproate solutions from measurements of density and the flow time. The standard partial molar volumes (V∘m,2), standard volumes of transfer (ΔtV∘), the viscosity B-coefficients, and the activation thermodynamic quantities (Δμ2∘≠ and ΔS2∘≠) of viscous flow have been calculated for the amino acids. It is shown that the standard partial molar volumes, viscosity B-coefficients, and activation free energies for viscous flow increase with increasing number of carbon atoms in the alkyl chain of the amino acids. An increase in V∘m,2 and ΔtV∘ with increasing electrolyte concentrations have been explained due to the interactions of sodium caproate with the charged center of zwitterions for the amino acids. A comparison of the V∘m,2 values for glycine, dl-α-alanine, and dl-α-aminon-n-butyric acid in different aqueous salts solutions showed that carboxylate ions have stronger interactions with amino acid than chloride, thiocyanate, and nitrate ions. Results of viscosity are discussed in terms of changes in solvent structure. [Copyright &y& Elsevier]

Apparent molar volumes V2,φ and standard partial molar volumes V2,φ0 of LiClO4, LiBr and three symmetrical tetraalkylammonium bromides R4NBr (R=ethyl, propyl, butyl) have been determined at 298.15 K from precise density measurements in solvent mixtures of ethylene carbonate with tetrahydrofuran (THF), acetonitrile (AN), ethyl acetate (EA) and dimethoxyethane (DME). It is shown that the V2,φ0 values of LiClO4 and LiBr are dependent strongly on the nature of the solvents, whereas the contribution of CH2 group to the partial molar volume of the tetraalkylammonium salts has nothing to do with the nature of the solvents and the composition of the solvent mixtures. This provided a helpful evidence for the unsolvation of large tetraalkylammonium cations in organic solvents. The results have been discussed from ion–solvent interactions and the dielectric effect of the solvents. [Copyright &y& Elsevier]

As a class of green and designable solvents, ionic liquids (ILs) have been used extensively in inorganic synthesis. In those schemes, ILs were usually used as reaction media to replace water and organic solvents, and/or used as stabilizer and capping agents to act like an amphiphilic molecule or polymer. However, the unique properties of ILs were not fully utilized in the area of material preparation. In this study, a new protocol of “ILs–water interfacial synthesis” was developed and used for the preparation of Ag nanomaterials. Taking the advantage of tunable property of ILs–water interface, Ag nanomaterials with different morphology such as triangular nanoplates, polygonal nanoplates, and nanoparticles could be facilely obtained. Growth mechanism of the triangular Ag nanoplates has been investigated from structural characterization and molecular dynamics (MD) simulation. It was shown that growth of the nanoplates was under kinetic control mainly due to high viscosity and ionicity of the ILs. Furthermore, the antimicrobial performance of these Ag samples was tested to study the influence of shape of the Ag nanomaterials on the antimicrobial activity and the related antimicrobial mechanism. The results suggested that the efficient antimicrobial activity of the triangular Ag nanoplates was ascribed to their sharp corners and edges and large areas of active (1 1 1) crystal plane, which leads to the higher amount of leaching Ag + ion. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing high-performance catalysts for water splitting via renewable electricity is of great significance for the clean production of hydrogen. This work reports rational design and controllable fabrication of metal oxide hybrid catalyst CoNiFe 2 O 5 ·2CuO with unique biphasic microstructures for electrochemical water splitting. Benefited from the presence of CuO nanoparticles as the second phase, more defects and active sites were formed around the interfaces of CoNiFe 2 O 5 and CuO, which led to excellent performances for electrocatalytic water splitting. In particular, the catalyst exhibited outstanding activity for hydrogen evolution reaction with a small overpotential of 30 mV to reach a current density of 10 mA cm−2 and showed a higher turnover frequency (0.3 s−1) than commercial catalyst Pt/C (0.1 s−1) under an overpotential of 50 mV. Moreover, it also displayed good activity for oxygen evolution reaction with an overpotential of 264 mV at 10 mA cm−2. Using CoNiFe 2 O 5 ·2CuO as the catalyst for electrode pair to construct a cell, a very low cell voltage of 1.53 V is enough to achieve overall water splitting at 10 mA cm−2 in 1 M KOH electrolyte, and the cell could maintain the stable performance at 10 mA cm−2 within 100 h. The as-prepared metal oxide hybrids with biphasic microstructures may have promising application potentials in water splitting. [ABSTRACT FROM AUTHOR]

Abstract: Densities of (d-xylose+HCl+water) have been measured at temperature in the range (278.15 to 318.15) K as a function of concentration of both d-xylose and hydrochloric acid. The densities have been used to estimate the molar volumes and isobaric expansivity of the ternary solutions. The molar volumes of the ternary solutions vary linearly with mole fraction of d-xylose. The standard partial molar volumes for d-xylose in aqueous solutions of molality (0.2, 0.4, 0.7, 1.1, 1.6, and 2.1) mol·kg−1 HCl have been determined. In the investigated temperature range, the relation: , can be used to describe the temperature dependence of the standard partial molar volumes. These results have, in conjunction with the results obtained in water, been used to deduce the standard volumes of transfer, Δt V ∘, of d-xylose from water to aqueous HCl solutions. An increase in the transfer volume of d-xylose with increasing HCl concentrations has been explained by the stronger interactions of H+ with the hydrophilic groups of d-xylose. [Copyright &y& Elsevier]

Density measurements have been carried out at T=298.15 K for the CsCl–monosaccharide (d-galactose, d-xylose and d-arabinose)–water systems. The apparent molar volume of saccharides Vφ,S in the ternary solutions, the corresponding infinite dilution apparent molar volume Vφ,S∘, and the standard transfer volume ΔtVφ,S∘ of saccharides from water to aqueous CsCl solutions have been determined. The McMillan–Mayer theory was employed to relate the excess thermodynamic functions to a series of interaction parameters to obtain the volumetric interaction parameters of CsCl with monosaccharide in water. These parameters are interpreted by the group additivity principle and the stereochemistry of these monosaccharide molecules. [Copyright &y& Elsevier]

Two-dimensional (2D) molybdenum disulfide (MoS 2) has drawn increasing attention due to its great potential for advanced electronics, photonics, optoelectronics, energy storage, catalysis and solar cell. However, high effective exfoliation for the mass production of 2D MoS 2 is still a challenge. To improve the exfoliation efficiency of MoS 2 nanosheets, a facile liquid-phase exfoliation strategy has been developed by using organic electrolyte solutions in this work. It is shown that the dispersion concentration of MoS 2 nanosheets has been significantly enhanced in organic electrolyte solutions. For example, by adding sodium tartrate into dimethyl sulphoxide, the dispersion concentration of MoS 2 nanosheets is 85 times that in neat dimethyl sulphoxide. About 80% of MoS 2 nanosheets obtained in such a strategy is 1–4 layers and the nanosheets remain 2H phase structure. In addition, the photocatalytic hydrogen evolution performance of the as-prepared few-layer MoS 2 nanosheets is evaluated. The photocatalytic hydrogen evolution rate is as high as 0.5 mmolg−1 h−1, which is 71 and 10 times higher than that of bulk MoS 2 and the 2H-MoS 2 nanosheets, respectively, reported to date. Exfoliation mechanism investigation suggests that the size of cation and the intensity of Lewis basicity of anion in the salts have played an important role in the exfoliation of MoS 2. The liquid exfoliation strategy reported here has great potential in the large-scale and high quality production of few-layer MoS 2 nanosheets for efficient photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Liquid phase exfoliation (LPE) method has great potential for the large-scale production of graphene due to its simplicity, scalability, and low cost. In this work, fulvic acid (FA) was chosen to assist the exfoliation of graphite into graphene for the first time via sonication in aqueous medium. The concentration of obtained graphene dispersion can reach 0.63 ± 0.04 mg mL−1. The graphene flakes mostly consisted of 1–5 layers with sizes range in submicron to micron and few defects in the basal-plane. The π–π interaction between graphene and FA, along with the electrostatic repulsion between negatively charged FA, played a major role in stabilization of the graphene dispersion. By adjusting the pH of graphene dispersion to 14, the nanosheets of graphene came to flocculation. The formed graphene slurry is favorable for storage and transportation due to the greatly decreased volume. The annealed coating of FA-graphene on aluminum sheets was used as corrosion inhibitor for aluminum in 0.5 M H 2 SO 4 and 0.6 M NaCl solutions, with inhibition efficiencies of up to 85.5% and 99.4%, respectively. This shows that as-prepared graphene has great potential applications in the anti-corrosion of aluminum. [ABSTRACT FROM AUTHOR]

Developing a simple and green route for the controlled synthesis of hierarchical nanomaterials with anisotropic particles as subunits is highly desirable and technically important. Here, a functionalized ionic liquid (FIL) assisted strategy is developed for the preparation of hierarchical Au nanomaterials at room temperature. Various morphologies of Au products, including nanoplate-built flowers, nanobar-built flowers and nanourchins, have been well achieved using the current route in aqueous solutions of imidazolium ILs with different functional groups, such as 1-carboxymethy-3-methylimidazolium chloride ([CMmim]Cl), 1-hydroxylethyl- 3-methylimidazolium chloride ([HEmim]Cl), and 1-(3-aminopropyl)-3- methylimidazolium chloride ([APmim]Cl). The influence of these FILs on the morphology of Au products and their growth process has been studied systematically. It is shown that the functionalized ILs play important roles in the construction of these interesting Au hierarchies. The seed, IL concentration (within a certain range), reaction temperature have negligible influence, but stirring and anions of the ILs have important influences, on the product morphologies. Based on these results, the possible growth mechanism is proposed for the formation of different Au hierarchies. In addition, all the Au samples prepared with the assistance of the functionalized ILs, especially the nanoplate-built flowers, exhibit striking SERS sensitivity and high reproducibility. [ABSTRACT FROM AUTHOR]

Liquid-phase exfoliation of graphite is a promising method to produce graphene in large quantities. Selection of the solvent is the most important factor in determining the productivity of liquid-phase exfoliation and stability of the graphene dispersion. However, only low concentrations of graphene dispersion have been achieved in most of the solvents, and the solvents usually employed are toxic up to now. To address the performance and environmental safety issues of solvent, renewable solvents water and 1, 1, 3, 3-tetramethylurea (TMU) are explored as a mixture to exfoliate graphite into graphene in the present work. It is found that water-TMU mixed solvent is a powerful solvent to obtain a few-layer graphene, and the yield at the water volume faction of 0.3 was 4.5 times that in neat N -methylpyrrolidinone (NMP). The solvent-cosolvent interactions (water-TMU heteroassociation) are a critical factor in the liquid-phase exfoliation of graphene. The results reported in this work may provide a guide to rational design of a sustainable solvent system and to improve the yield and stability of the exfoliated graphene. [ABSTRACT FROM AUTHOR]

Searching for environmentally friendly aqueous two-phase systems is imperative for the sustainable development of separation technologies. In this work, five kinds of environmentally benign choline derivative ionic liquids were synthesized and used for the formation of aqueous two-phase systems with K 3 PO 4 , K 3 C 6 H 5 O 7 or K 2 CO 3 . In order to understand the phase formation processes of these aqueous two-phase systems and their possible application in extraction, phase diagrams and partition coefficients of purine alkaloids were determined at T  = 298.2 K, and the effects of structure of the ionic liquids, nature of the purine alkaloids, composition and temperature of the systems on the partitioning behaviour of purine alkaloids were investigated systematically. It was shown that caffeine, theobromine and 2,6-amino purine could be extracted effectively into the ionic liquid-rich phase of the aqueous two-phase systems, and the partition coefficients were as high as 4.5–42 under the optimized conditions. The partitioning was found to decrease with the increase of the ratio of H 2 O weight fraction (in the ionic liquid-rich phase and in the salt-rich phase) and hydrophobicity of both the purine alkaloids and the ionic liquids, but not sensitive to the change of temperature. [ABSTRACT FROM AUTHOR]

Ionic liquids are widely recognized new materials in carbon dioxide capture and separation technology. In this work, we synthesized and characterized two kinds of ether-functionalized imidazolium ionic liquids, 1-methoxyethyl-3-methylimidazolium hexafluoroborate ([EOMmim][PF 6 ]) and 1-methoxyethyl-3-methylimidazolium bis(trifluoro-methylsulfony)imide ([EOMmim][Tf 2 N]). Solubility values of CO 2 in these ionic liquids were determined by isometric weight method at the temperatures from 298.15 K to 343.15 K and the pressure up to 5.185 MPa. Furthermore, solubilities of other flue gases, N 2 and O 2 , in these two ionic liquids were also measured at 303.15 K. It was shown that little influence had been exerted on CO 2 solubility by the introduction of ether groups on the cation, but it decreased N 2 and O 2 solubility, resulting in the remarkable increase of CO 2 /N 2 and CO 2 /O 2 selectivity. In addition, the solubility data were well correlated by Pitzer model, and the standard state solution Gibbs energy, solution enthalpy and solution entropy of CO 2 in the two ionic liquids were reported. Regeneration characteristics of the investigated ionic liquids was also studied by vacuum desorption and atmospheric desorption, respectively. [ABSTRACT FROM AUTHOR]

The development of a simple, template-free, and one-step strategy to synthesize nanostructured Au architectures with fascinating morphology is highly desirable and technically important due to their valuable applications in varied fields. In this work, the “green” strategy of “tunable ionic liquids-water (ILs-H 2 O) interfacial synthesis” developed previously by us is utilized for feasible synthesis of gold needle mushroom-like micro/nanostructures at the 1,3-dibutylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 bim][Tf 2 N]) - water interface and ambient conditions. The as-obtained gold needle mushrooms (AuNMs) have been characterized and analyzed systemically by scanning electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. It is shown that the as-prepared AuNMs can be used as substrates to perform surface enhanced Raman scattering (SERS) investigation with striking SERS sensitivity. By employing ILs with different alkyl chain lengths of the imidazolium cations and/or different nature of anions, Au nanomaterials with diverse morphologies can be easily prepared at different ILs-H 2 O interfaces. Based on the analysis of the control experiments, the growth and formation of AuNMs at the [C 4 bim][Tf 2 N]-H 2 O interface have been discussed. [ABSTRACT FROM AUTHOR]

The thermodynamics and phase behavior of mixtures of cationic gemini surfactant decanediyl-α,ω-bis(dodecyldimethylammonium bromide) (12-10-12) and sodium dodecylsulfate (SDS) were studied in the dilute SDS-rich region. The enthalpy of interaction between both surfactant monomers before the critical micelle concentration for the mixture (cmc mix ) was determined by isothermal titration calorimetry (ITC). After the cmc mix , ITC results exhibited a first process associated with a large endothermic enthalpy change followed by a second one with a very small exothermic enthalpy change. In the same regions, the conductivity curves show an increase in slope after the break, followed by a plateau region, respectively for the two processes. The combined results from the various methodologies used lead us to propose that the first process reflects the formation of non-spherical micelles and the second one the vesicle formation. The area per catanionic complex was obtained through surface pressure measurements, leading to an apparent packing parameter ⩾1. The observed behavior may be rationalized on the basis of the hypothesis that both surfactants distribute asymmetrically in the vesicle bilayers and unevenly in the non-spherical micelle. In order to get structural information Cryo-TEM experiments were performed, which provided images that support this interpretation. From all the information gathered a phase diagram was mapped, including three one-phase regions of spherical micelles, non-spherical micelles and vesicles. [ABSTRACT FROM AUTHOR]

Highlights: [•] The microemulsions composed of cholinium-based ionic liquid, Triton X-100 and water have been prepared and characterised. [•] Ternary phase diagrams of the microemulsions have been established at T =298.15K. [•] The microemulsions exhibit IL-in-water, bicontinuous and water-in-IL microstructures. [•] Droplets with the size smaller than 20nm are formed in these IL-based microemulsions. [ABSTRACT FROM AUTHOR]

Highlights: [•] The values of and Δt V° are positive. [•] Interactions of Triton X-100 with charged and polar groups of dipeptides dominate. [•] Addition of dipeptide in water decreases the c cmc and the aggregation number of Triton X-100. [•] The affinity between dipeptide and Triton X-100 micelle increases with the increase in the length of alkyl chain of peptides. [•] Triton X-100 interacts with dipeptides more weakly than SDS. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a series of novel room temperature ionic liquids (ILs) have been synthesized with cheap, naturally α-amino acid ester as cations and bis(trifluoromethylsulfonyl)imide as anion. The glass transition temperature and thermal decomposition temperature of these ILs, partition coefficients of some coumarins and purine alkaloids between water and the amino acid ester-based ILs at T =298.15K, and Gibbs energy, enthalpy and entropy changes for the transfer of caffeine and 6,7-dihydroxycoumarin from water to [LeuC2][Tf2N] have been determined. It is shown that these ILs are highly effective materials for the extraction of drug compounds like coumarin, 4-hydroxycoumarin, 7-hydroxycoumarin, 3-aminocoumarin, coumarin-3-carboxylic acid, 6,7-dihydroxycoumarin, 6,7-dihydroxy-4-methylcoumarin, caffeine, theobromine, theophylline, inosine, and 2,6-diaminopurine. The partition process is driven by enthalpy term, and partition coefficients of the drug molecules increase with the increase of hydrophobicity of both the drug molecules and the ILs. Furthermore, the possible partition mechanism has been investigated from 13C NMR measurements. [Copyright &y& Elsevier]

Abstract: Searching for environmentally friendly aqueous two-phase systems is imperative for the sustainable development of bioseparation technologies. In the present work, (liquid+liquid) equilibrium data have been determined experimentally for aqueous two-phase systems formed by the cholinium-based ionic liquids (cholinium glycollate, cholinium propionate, cholinium lactate, and choline chloride) and polymers {polypropylene glycol 400 (PPG400), polypropylene glycol 1000 (PPG1000), and poly(ethylene glycol)-block-poly(propylene glycol)-poly(ethylene glycol) (EO10PO90)}. The effects of anion type of the ionic liquids, the nature of the polymers and temperature of the systems are examined on the phase-forming capacity of the systems. Then the binodal results have been satisfactorily fitted to a three-parameter empirical equation. The tie-line data are well described by the Othmer–Tobias and Bancroft equations. [Copyright &y& Elsevier]

Abstract: Ionic liquids (ILs) are promising in the capture and separation of CO2. In this work, IL 1-n-butyl-3-methylimidazolium heptafluorobutyrate, [C4mim][CF3CF2CF2COO], has been synthesized and characterized by 1H, 13C and 19F NMR spectra. Solubilities of CO2, H2, N2 and O2 in this IL have been determined at the temperature range from (303.15 to 333.15)K and the pressure up to 8.9MPa. From these data, the Henry’s constant, the standard state solution Gibbs energy, standard state solution enthalpy and standard state solution entropy of these gases in [C4mim][CF3CF2CF2COO] were derived and analyzed from molecular interactions. It was shown that the solubility of CO2 is obviously higher than that in [C4mim][CF3COO] and [C4mim][CF3SO3] reported in literature, which makes this IL an attractive solvent for gas separation processes. Furthermore, these solubility data were well correlated by Pitzer model. [Copyright &y& Elsevier]

Abstract: The interactions of glycyl dipeptides (glyglycine, glycyl-l-valine and glycyl-l-leucine) with sodium perfluorooctanoate (SPFO) in aqueous solutions have been investigated by means of density, conductivity, fluorescence spectroscopy, and UV–vis spectroscopy. The standard partial molar volume (), standard partial molar volume of transfer for dipeptide from water to aqueous SPFO solutions (Δt V o), partial molar expansibility () and Hepler’s constant have been calculated from density data. Electrical conductivity was used to estimate the critical micellar concentration (ccmc) and the thermodynamic parameters of micellization of SPFO in aqueous glycyl dipeptide solutions. Effects of temperature and hydrocarbon chain length of the glycyl dipeptides on the volumetric properties of dipeptides and critical micelle concentration (ccmc) of SPFO were examined. The pyrene fluorescence spectra were used to study the change of micropolarity produced by the interactions of SPFO with glycyl dipeptides, and the aggregation behaviour of SPFO. From the results of UV-vis absorption spectra, the binding constant between dipeptide and SPFO above the ccmc was determined. [Copyright &y& Elsevier]

Abstract: A novel method was proposed for successful fabrication of CuS nanostructures with various morphologies. At the ionic liquids (ILs)-modulated CHCl3–H2O interface, copper cupferronate [Cu(cup)2] in CHCl3 reacted with thiourea in water to generate CuS nanostructures via a solvothermal reaction process. The effects of alkyl chain length of imidazolium cations and nature of anions of the ILs, molar ratio of Cu(cup)2 to thiourea, the reaction temperature and time on the morphology of the products were studied systematically. It was shown that by changing alkyl chain length of imidazolium cations and nature of anions of the ILs, CuS nanostructures with various morphologies, including flowers, urchins, large nanodisks and nanoparticles, could be obtained at the liquid–liquid interface, and the ILs played important template roles in directing the formation of CuS nanostructures. Furthermore, the as-prepared CuS samples exhibited high catalytic activity for photodegradation of methyl orange and thermal decomposition of ammonium perchlorate. [Copyright &y& Elsevier]

Abstract: The interactions of glycyl dipeptides (glycylglycine, glycyl-l-valine and glycyl-l-leucine) with sodium caprylate (NaC8) in aqueous solution have been investigated by a combination of density, conductivity and fluorescence methods. Apparent molar volumes (V 2, ϕ ), standard partial molar volumes (), and standard partial molar volumes of transfer from water to aqueous NaC8 solutions (Δ t V o) are evaluated using density data. The limiting molar conductivity of sodium caprylate (Λ o) and its anion contribution , as well as the Stokes’ radii of caprylate anion in aqueous glycyl dipeptide solutions have been calculated using conductivity data. Pyrene fluorescence spectra were used to estimate the critical micellar concentration (c cmc) of NaC8 in aqueous dipeptide solutions. The analysis shows that the interactions of sodium caprylate with charged and polar groups of glycyl dipeptides are dominating over the sodium caprylate-non-polar group interactions over the entire concentration range of sodium caprylate. From the volumetric data, it is suggested that the glycyl dipeptides are solubilized in the palisade layer of sodium caprylate micelles. The decrease in Λ o values of sodium caprylate with an increase in dipeptide concentration is attributed to the interaction of sodium caprylate with the dipeptides and increasing viscosity of solvent. The addition of dipeptide in water decreases the c cmc of NaC8. The interactions of glycyl dipeptides with sodium caprylate increase with the increase in the size of side chain of carboxylate anions and of glycyl dipeptides. [Copyright &y& Elsevier]

Abstract: In this paper, the interactions between cationic dyes and the ionic liquids (ILs) have been studied by 31P nuclear magnetic resonance (NMR), UV–Vis spectroscopy and conductometric measurements at different temperatures. It was shown that a decrease in the measured specific conductance of the (dye+IL) mixtures was caused by the formation of non-conducting or less conducting (dye+IL) associates. The associates were formed by 1:1 ratio of cation of the cationic dyes and anion of the ILs by using the 31P NMR and UV–Vis spectroscopy methods. The association constants were calculated by theoretical model based on the deviation from linear behavior, and the association constants were as high as 106 (L·mol−1)2. Thermodynamic results imply that the formation process of association was exothermic nature. It is expected that the associates reported here would have promising application as active materials for the preparation of ion-selective electrode used in the determination of ILs concentrations. [Copyright &y& Elsevier]

Abstract: 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 ([C10mim]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 [C10mim]Cl—the critical aggregation concentration (CAC), ionization degree of the aggregates (α), the standard Gibbs energy of aggregation (), 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 [C10mim]Cl was proposed. [Copyright &y& Elsevier]

Abstract: Densities, conductivities, and fluorescence spectra of {sodium dodecyl sulfate (SDS)+glutamine dipeptide+water} mixtures were measured as a function of temperature. The density data have been utilized to calculate apparent molar volumes, standard partial molar volumes (), standard partial molar volumes of transfer from water to aqueous SDS solutions (Δt V o), the hydration number, partial molar expansibility (), and Hepler’s constant of glutamine dipeptides. The critical micellar concentration (c cmc) and the degree of counterion dissociation of SDS micelles obtained from electrical conductivity data have been estimated at various concentrations of glutamine dipeptide. Thermodynamic parameters of micellization of SDS in aqueous dipeptide solutions have been determined from c cmc values and an enthalpy–entropy compensation effect was observed for the ternary systems. The pyrene fluorescence spectra were used to study the change of micropolarity produced by the interaction of SDS with glutamine dipeptide, and the aggregation behavior of SDS. The results have been interpreted in terms of solute–solvent interactions and structural changes in the mixed solutions. [Copyright &y& Elsevier]

Abstract: In the present work, (liquid+liquid) equilibrium data have been determined experimentally for aqueous two-phase systems formed by the imidazolium ionic liquids of [C n mim][CH3COO] (n =4, 6, 8) and inorganic salts of K3PO4, K2HPO4, and K2CO3 at T =298.15K. Combined with available data in the literature, the effect of alkyl chain length of cations, type of anions of the ionic liquids, and nature of the inorganic salts were examined on the binodal curves of the systems. Then the binodal curves were fitted to a four-parameter empirical equation, and the tie-lines were described by the Othmer–Tobias and Bancroft equations. In addition, the extraction capacity of the {[C n mim][CH3COO] (n =4, 6, 8)+K3PO4} aqueous two-phase systems was evaluated through their application to the extraction of l-tryptophan. The high extraction efficiency suggests that these aqueous two-phase systems are feasible to be used in the extraction and separation process. [Copyright &y& Elsevier]

Abstract: Activity coefficients for the (CaCl2 +amino acid+water) system were determined at a temperature of 298.15K using ion-selective electrodes. The range of molalities of CaCl2 is (0.01 to 0.20)mol·kg−1, and that of amino acids is (0.10 to 0.40)mol·kg−1. The activity coefficients obtained from the Debye–Hückel extended equation and the Pitzer equation are in good agreement with each other. Results show that the interactions between CaCl2 and amino acid are controlled mainly by the electrostatic interactions (attraction). Gibbs free energy interaction parameters (g EA) and salting constants (k S) are positive, indicating that these amino acids are salted out by CaCl2. These results are discussed based on group additivity model. [Copyright &y& Elsevier]

Abstract: Densities and conductivity data for the sodium carboxylate (sodium acetate and sodium butyrate)–dipeptides {(glycyl-l-glutamine and l-alanyl-l-glutamine)+water} systems were determined at T =298.15K. The apparent molar volumes of the peptides and the molar conductivity (Λ) of sodium acetate and sodium butyrate have been calculated. These data have been utilized to deduce the standard partial molar volumes (), standard partial molar volumes of transfer for dipeptide from water to aqueous sodium carboxylate solutions (Δt V °), volumetric interaction coefficient, the limiting molar conductivity (Λ °), and Walden product (Λ ° η). Both and Δt V ° for the dipeptides increase with increasing concentration of sodium carboxylate. The interpretation is that this result arises from the dominant interactions of the sodium carboxylate with the charged group and polar groups of peptides. The decrease in Λ ° of sodium carboxylate with increasing dipeptide concentration and nonconstant Walden product are attributed to the interactions of sodium carboxylate with peptide and friction resistance of the solvent medium. [Copyright &y& Elsevier]

Abstract: Activity coefficients of CaCl2 in disaccharide {(maltose, lactose)+water} mixtures at 298.15K were determined by cell potentials. The molalities of CaCl2 ranged from about 0.01mol·kg−1 to 0.20mol·kg−1, the mass fractions of maltose from 0.05 to 0.25, and those of lactose from 0.025 to 0.125. The cell potentials were analyzed by using the Debye–Hückel extended equation and the Pitzer equation. The activity coefficients obtained from the two theoretical models are in good agreement with each other. Gibbs free energy interaction parameters (g ES) and salting constants (k S) were also obtained. These were discussed in terms of the stereo-chemistry of saccharide molecules and the structural interaction model. [Copyright &y& Elsevier]