Apparent Molar Expansibility Research Articles

Volumetric and acoustic properties of L-phenyl glycine and L-phenylalanine in aqueous solution of 1-dodecyl-3-methylimidazolium bromide [C12mim] [Br

To study the molecular interactions between the ternary mixtures containing long chain imidazolium based ionic liquid as a common solvent with substituted amino acids L-phenyl glycine and L-phenylalanine respectively, densities and speed of sound have been measured at three different temperatures viz. T = 288.15 K, 298.15 K, 318.15 and 318.15 K under 0.1 MPa pressure. The density and speed of sound data have been further utilized to calculate the apparent molar volume and apparent molar isentropic compression. From the data obtained, apparent molar volume (Vϕ), partial molar volume (Vϕ0), and standard partial molar volumes of transfer (ΔVϕ0). Positive values of apparent molar volume indicate strong interactions. Also, partial molar isentropic compression of transfer (ΔKϕ,S0) and partial molar isentropic compression (Kϕ,s) have been calculated from the sound of speed. Furthermore, structure making and structure breaking ability of solute have been discussed by evaluation of apparent molar expansivity, (ϕE0), Hepler's constant values ∂/∂Tp. The obtained results have been discussed in terms of solvation behavior, structural changes and various interactions present in different ternary mixtures (1-dodecyl-3-methylimidazolium bromide + amino acids + water).

Effect of trisodium citrate dihydrate on thermophysical properties of saccharides in aqueous media at different temperatures: Volumetric and acoustic properties

From the measurements of density, (ρ) and speed of sound, (u), the intermolecular interactions of D-maltose monohydrate and D-lactose monohydrate with trisodium citrate (TSC) have been explored in aqueous medium at temperatures, T = (293.15–313.15) K, pressure p = 0.1 MPa. From the experimental density measurements, apparent molar volume (VΦ), limiting apparent molar volume (VoΦ) and limiting apparent molar volume of transfer (VoΦ,tr) have been determined for various solutions of maltose and lactose in aqueous TSC. In addition, using experimental speed of sound data, apparent molar isentropic compressibility (KΦ,s), limiting apparent molar isentropic compressibility (KoΦ,s) and partial molar isentropic compression of transfer (KoΦ,s,tr) have been calculated.Further, apparent molar expansibility (EoΦ), Hepler's constant values(∂EoΦ∂T)Pand hydration number (nH)have been assessed to contribute the interpretations received from the acoustic and analysis. The assessed outcomes were construed in terms of diverse intermolecular interactions present in the ternary systems (saccharides+ water + TSC) through a co-sphere overlap model. From the Hepler's constant structure breaking nature of the solute have been confirmed.

Understanding ion–ion and ion–solvent interactions in aqueous solutions of morpholinium ionic liquids with N-acetyl-L-alaninate anion through partial molar properties and molecular dynamics simulations

Amino acid ionic liquids (AAILs) provide a low toxicity, biodegradable alternative to conventional ionic liquids, while also maintaining solubility in water. Densities and sound velocities of aqueous solutions of four amino acid ionic liquids (AAILs), based on the N-alkyl-N-methylmorpholinium ([Mor1,R], R = 2, 3, 6, 8) cation and N-acetyl-L-alaninate ([N-Ac-L-Ala]) anion were measured at T = (293.15–313.15) K and at atmospheric pressure. These data were used to derive the apparent molar volumes and the apparent molar compressibilities in the concentration range of (0.02–0.3) mol kg−1. Established extrapolation procedures were applied to estimate the values of the limiting apparent molar volumes and the limiting apparent molar compressibilities. The limiting apparent molar expansibility coefficients were obtained and the hydration numbers for AAILs in aqueous solution were calculated using Passynski’s method. The results indicate that ion–solvent interactions in the studied solutions are determined by the hydrophobic effect and the charge effect, which are both dependent on temperature. At low temperatures the ion–solvent interactions are determined by the hydrophobic effect which results in the decrease of the limiting apparent molar compressibilities with an elongation of the alkyl chain of the cation of AAIL. At high temperatures the charge effect is dominant due to the decreasing limiting apparent molar compressibilities. On the other hand, ion–ion interactions are dominated by the hydrophobic effect regardless of the temperature. Molecular dynamics simulations were also performed and applied in interpretation of experimental data at atomistic detail. Computed limiting apparent molar volumes correlate well with the values derived from experiment. The apparent hydration volume, obtained by subtracting the intrinsic volume contribution, is large and positive, indicating hydrophobic hydration and not electrostriction is the principal mode of ions’ influence on the solvent. Analysis of radial distribution functions confirms insignificant share of ion–ion interactions via contact ion pairing. The solvation shells signify predominantly hydrophobic hydration, with locally strongly hydrated functional groups.

Volumetric, acoustic and viscometric studies of solute-solute and solute-solvent interactions of glycine and its peptides in aqueous solutions of an antidepressant drug at different temperatures

From the density (ρ), speed of sound (u) and viscosity (η) measurements, the interactions of glycine, glycylglycine and glycylglycylglycine with antidepressant drug, nortriptyline hydrochloride have been investigated in aqueous medium at temperatures, T = (293.15–313.15) K and experimental pressure p = 0.1 MPa. From the experimental density measurements, apparent molar volume (VΦ), limiting apparent molar volume (VoΦ) and partial molar volumes of transfer (VoΦ,tr) have been determined for various solutions of glycine, glycylglycine and glycylglycylglycine in aqueous nortriptyline hydrochloride. In addition, using speed of sound data, apparent molar isentropic compression (Ks,Φ), limiting apparent molar isentropic compression (Kos,Φ) and partial molar isentropic compression of transfer (Kos,Φ,tr) have been calculated. Pair and triplet interaction coefficients are also determined from VoΦ,tr values using McMillan-Mayer theory. Further, apparent molar expansibility (EoΦ) and Hepler's constant values ∂EoΦ∂TP have been evaluated to assist the interpretations earned from the volumetric and acoustic analysis. The viscosity coefficients A and B, viscosity B-coefficient of transfer (Btr) and temperature derivative of B-coefficients (dB/dT) have been determined from viscosity data. The results were interpreted in terms of different kinds of intermolecular interactions present in the ternary systems (amino acid/peptides + water + nortriptyline hydrochloride) through a cosphere overlap model. The Hepler’s constant and temperature derivative of B-coefficients (dB/dT) confirms the structure breaking nature of the solute.

Elucidation of molecular interactions of aspartic acid with aqueous potassium sorbate and sodium benzoate: Volumetric, viscometric and FTIR spectroscopic investigation

Aspartic acid (Asp), a nonessential amino acid has been taken for the present study. Solutions of different concentrations of aspartic acid were prepared by dissolving it in water and {water + (1.5, 2.0 and 2.5 m) Potassium sorbate (PS)/sodium benzoate (SB)}. Density and viscosity of the solutions were experimentally determined at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K. Volumetric parameters like apparent molar volume (V∅), partial apparent molar volume (V∅0), partial apparent molar expansibility (E∅0) were computed by using standard formulations. Stronger ion-ion, ion-hydrophilic and hydrophilic-hydrophilic interactions between zwitterionic centers (COO- and NH3+) and polar groups of aspartic acid (COOH and NH2) and ions present in aqueous PS/SB are found to dominate the hydrophobic interactions between the nonpolar organic segments of amino acid and PS/SB. Structure building character of aspartic acid in presence of PS/SB are established by the positive values of Hepler’s constant (∂2V∅0/∂T2)P for all compositions of solutions. Positive viscosity B-coefficient (BJ) and negative (∂BJ/∂T)values further establish the structure building character of aspartic acid. Thermodynamic parameters for viscous flow (Δμ20,#,ΔS0,#andΔH0,#) suggest that transition state for viscous flow is less stable than the ground state and formation of transitions state is not thermodynamically favoured. Shifting of IR absorption band for O-H stretching due to H-bonding at 3300–3340 cm-1 confirms changes in solvent structure due to ion-ion and ion–solvent interactions occurring in the investigated systems.

Volumetric and acoustic studies of aqueous l-arginine·HCl and l-proline in electrolytic and non-electrolytic solutions at various temperatures

Densities and speed of sound of l-arginine hydrochloride and l-proline within the concentration range (0.03–0.2) mol.kg−1 in water and in aqueous NaCl and Urea are determined between temperatures 288.15 K and 318.15 K and at one atmospheric pressure. Densities and speeds of sound have been used to calculate apparent molar volume of solute (Vφ), isentropic compressibility of solution (κS), apparent molar isentropic compressibility (KS,φ) of solute, limiting apparent molar volume (Vφ0), limiting apparent molar volume of transfer (ΔtrVφ0), limiting apparent molar expansibility (Eφ0), limiting apparent molar isentropic compressibility (KS,φ0) and limiting apparent molar isentropic compressibility of transfer (ΔtrKS,φ0). These results are then interpreted in terms of intermolecular interactions. The concentration dependencies of the calculated quantities, their limiting values and temperature characteristics are discussed in terms of solute - solvent and solute - solute interactions at experimental conditions.

Investigation of the inter-ionic interactions of an imidazolium-based ionic liquid with the aqueous solutions of tripotassium citrate and trisodium citrate through volumetric, acoustic and FTIR routes

Volumetric, acoustic and spectroscopic characteristics of an imidazolium-based ionic liquid, 1-Butyl-3-methylimidazolium chloride ([bmim][Cl]) in water and aqueous solutions of tri-potassium citrate, K3Cit, and tri-sodium citrate, Na3Cit were studied at five different temperatures T = (298.15 K, 303.15 K, 308.15 K, 313.15Kand 318.15 K) and atmospheric pressure (0.1Mpa). The apparent molar volume,Vϕ, and apparent molar compressibility, Kϕ,S were computed from the experimental data of densities and ultrasonic speeds. The derived properties such as standard partial molar volume, Vϕ0 , partial molar compressibilities, Kϕ,S0, limiting apparent molar expansivity, Eϕ0, and their corresponding transfer volumes, ΔtrVϕ0, transfer compressibilities, ΔtrKϕ,S0, of [bmim][Cl] from water to aqueous potassium/sodium citrate solutions were also determined. The transfer properties have been used to discuss the solute-solvent interactions that exist in the solutions. The positive value of Hepler’s constant indicates that the IL has structure-making ability in the studied solutions. In addition, FTIR spectroscopy was executed on the systems. Based on these data, the predominant molecular interactions occurring between [bmim][Cl] and water and in between [bmim][Cl] and K3Cit/Na3Cit were found to be hydrogen bonds.

Volumetric, acoustic and viscometric properties of l-leucine and glycyl-l-leucine in aqueous solutions of isoniazid at different temperatures

Amidst stupendously studies accomplished to unriddle the solute–solvent interactions, volumetric, acoustic and viscometric studies hold a consequential position. In the existing work, l-leucine and glycyl-l-leucine act as solute in aqueous isoniazid (solvent) in order to descry the solute–solvent interactions in the system at different temperatures and at atmospheric pressure. The experimental density has been employed in evaluating the volumetric parameters like apparent molar volume (Vϕ), limiting apparent molar volume (Voϕ), transfer parameters of volume (ΔtrV°ϕ) and limiting apparent molar expansibility (E°∅). The speed of sound has been applied in evaluating the compressibility parameters like apparent molar isentropic compression, limiting apparent molar isentropic compression (K°ϕ,s) and its transfer parameter (ΔtrK°ϕ,S). The transfer parameters deduct the interactions in the system on the behalf of co-sphere overlap model which shows dominating nature of the hydrophilic-hydrophilic interactions. Pair (VAB, KAB) and triplet (VABB, KABB) coefficient are also calculated. Using the viscosity data, the relative viscosity (ηr) and viscosity B-coefficient are calculated. The Hepler’s constant (∂E°∅/∂T) and first temperature derivative of B-coefficients (dB/dT) has been used to anatomize whether solute acts as structure maker or structure breaker in the solution.

Thermodynamic study of the aqueous pseudo-binary mixtures of betaine-based deep eutectic solvents at T = (293.15 to 313.15) K

ABSTRACT This work investigates physicochemical properties of betaine/propylene glycol (Bet/PG) and betaine/ethylene glycol (Bet/EG) DESs in water by measuring their densities in neat state and aqueous mixtures over the entire composition range at T = (288.15–318.15) K under atmospheric pressure (≈ 85 kPa). The obtained values of density were used to compute the excess molar volumes (), molar volume (V m), apparent molar volume (), limiting apparent molar expansibility () and the isobaric thermal expansion coefficient (). The solute-solvent interactions in the investigated solutions are evaluated on the basis of these important physicochemical properties. The results indicated that two studied DESs act as a structure-making solute in water over the whole temperature range using Hepler’s constant. Finally, the experimental densities were correlated with some models including Jouyban-Acree, Jouyban-Acree-van’t Hoff, modified Jouyban-Acree-van’t Hoff, Redlich-Kister and Emmerling. The Redlich-Kister expression and Jouyban-Acree model were also used for representation of values.

Study of Solvation Behavior Thermodynamics and FT-IR Spectroscopic Analysis of N-Butylethanolammonium Based Ionic Liquids with Polar Solvents

The effect of anion geometry on aggregation behavior of surfactant with aqueous solutions was investigated by the systematic measurements of concentration, temperature dependent density and derived thermodynamic properties. In this work, N-Butylethanolammonium trifluoroacetate [BEATFA] and N-Butylethanolammonium nitrate [BEAN] ionic liquids (ILs) were synthesized and characterized by 1H NMR. The binary systems IL+water/ethanol were prepared for the concentration ranges from 0.0264 to 0.4621 mol·kg−1 and the temperature ranges from 298.15 K to 318.15 K. Further, the apparent molar volume (Vɸ), partial molar volume (Vɸ∞), thermal expansion coefficient (α) and apparent molar expansivity (Eɸ) were derived from the experimentally measured density data. The critical aggregation concentration (cac), apparent molar volume at critical aggregation concentration (Vɸ,CAC), apparent molar volume in aggregation phase (Vɸ,mic), change in apparent molar volume due to aggregation (∆Vɸ,m) and degree of ionization (α′) were derived from the plot of apparent molar volume versus inverse of ILs concentration. The thermodynamic aggregation properties such as standard Gibb's free energy of micellization (∆Gom), standard enthalpy of micellization (∆Hom) and standard entropy of micellization (∆Som) were calculated from experimental measurements. The sign and magnitude of apparent molar volume at infinity dilution reveals about IL+solvent or IL-IL interactions between the component molecules. The system [BEAN]+water showed lowest positive magnitude in both Vɸ∞ and cac than compare to [BEATFA]+water due to the formation of stronger IL+solvent intermolecular interactions through the H-bonding. The variance in observed Vɸ∞ and cac data with different solvents due to the solvophobic effect and hydrogen bonding tendency was explained by FT-IR spectroscopy and DFT computational study. Among the all binary systems, [BEAN]+water showed highest intermolecular interaction tendency than other systems, the obtained results were compared with available literature data and analyzed in terms of intra and intermolecular interactions, polarity of solvents, hydrophobicity, nature anion, size and shape of the anion.

Study on the physico-chemical properties of binary and ternary mixtures of diclofenac potassium, water and nicotinamide at T = (298.15–313.15) K

A study on the drugs physicochemical properties in aqueous and aqueous hydrotropic agent media in relation to the change in concentration and temperature was performed. To relieve pain and swelling from various painful health conditions, diclofenac potassium is prescribed depending on health condition, response to treatment, and medications other than this if continuing. This article aims to interpret different interactions prevailing in drug solutions for which NSAID, diclofenac potassium is chosen as the drug solute. Water and aqueous 1 M nicotinamide are the solvents chosen for the investigation of the molecular interactions. The experimental density values were obtained using a specific gravity bottle and were used to calculate various volumetric properties including apparent molar volume (Vϕ), partial molar volume (Vϕ0), apparent molar expansibility (Eϕ) and limiting apparent molar expansibility (Eϕ0). The viscosity results were examined using the Jones-Dole relation and from which AF (Falkenhagen coefficient) and BJ(Jones-Dole coefficient) are evaluated and discussed. The variations of these parameters were analyzed with respect to temperature and concentration to shed light on different molecular interactions.

Study of thermophysical properties of binary mixtures of N-phenyl ethanolammonium based protic ionic liquids with water and ethanol solvents

This work reveals that the physicochemical properties such as density, ρ and speed of sound, u for the binary mixtures of N-phenylethanolammonium formate ([NPEA][For]) and N-phenylethanolammonium acetate ([NPEA][Ace] with water and ethanol solvents were experimentally measured for the temperature ranges from 293.15 K to 318.15 K at atmosphere pressure. The apparent molar volume, VΦ and apparent molar isentropic compressibility, κs,Φ were estimated from the experimental data. Redlich-Mayer type empirical equation was applied to calculate the limiting apparent molar properties at infinite dilution (Vω∞ and kϕ∞) and corresponding empirical parameters (Sv, Bv, Sk and Bk). The type of interaction either IL-solvent or IL-IL or solvent-solvent occurring in solution were determined from the data of empirical parameters. Furthermore, the temperature dependent apparent molar volume at infinite dilution, Vϕ∞ was used to calculate the apparent molar expansibility at infinite dilution, Eϕ∞. Moreover, these Eϕ∞ values of the studied binary solutions were found to be positive. The making and breaking structure ability of both PILs were analyzed at all experimental conditions.

Volumetric properties, conductivity and computation analysis of selected imidazolium chloride ionic liquids in ethylene glycol

In this paper, the influence of the side chain length of five ionic liquids (ILs): 1-methylimidazolium chloride ([C0mim][Cl]), 1,3-dimethylimidazolium chloride (([C1mim][Cl]), 1-ethyl-3-methylimidazolium chloride (([C2mim][Cl]), 1-butyl-3-methylimidazolium chloride (([C4mim][Cl]) and 1-hexyl-3-methylimidazolium chloride (([C6mim][Cl]) on the interactions with ethylene glycol (EG) was studied. Based on the measurement of density and electrical conductivity of the ionic liquid + EG mixture in the temperature range (278.15–313.15) K, the values of apparent molar volume, standard partial molar volumes, apparent molar volume at infinite dilution, Masson’s interaction coefficient, thermal expansion coefficient, limiting apparent molar expansibilities, Heppler’s coefficient, ion association constants, thermodynamic parameters of ion-pair formation as well as diffusion coefficient was calculated. Experimental results were supported by molecular dynamic simulations. With the increase of the side chain length, from C0mim+ to C6mim+ cation, ion–dipole interactions on the solvation process decrease, and the influence of solvophobic solvation increases. Ionic liquids [C0mim][Cl] and [C1mim][Cl] show structure-breaker properties, [C4mim][Cl] and [C6mim][Cl] structure-making properties in EG solutions, while [C2mim][Cl] is borderline. The values of ion association constants in EG are higher than in water. The ion association process is spontaneous for all ionic liquids and entropy-driven.

Deep eutectic solvents for antiepileptic drug phenytoin solubilization: thermodynamic study

Thermodynamic investigations provide information about the solute-solvent interactions in the selection of the proper solvent for different fields of pharmaceutical sciences. Especially, the study of antiepileptic drugs in solutions (ethanol/co-solvent) has been a subject of interest owing to their effect in the systems using interaction with a number of important biological membranes. This work focuses on the measurement of density and speed of sound of the phenytoin (PTH) in ethanol/deep eutectic solvents (choline chloride:ethylene glycol, and choline chloride:glycerol) solutions as the innovative class of green solvents at temperature range (288.15 to 318.15) K. It was determined Hansen solubility parameters for assessment of PTH interactions in the solvent media. Some thermophysical parameters including apparent molar volumes Vϕ, apparent molar isobaric expansion E_varphi^0, and Hepler’s constant, apparent molar isentropic compressibility κφ were obtained and calculated using these data. To correlate the Vϕ and κφ values, the Redlich-Meyer equation was used to calculate the number of quantities containing standard partial molar volume and partial molar isentropic compressibility. Finally, Delta delta values showed a strong interaction between PTH and solvent (ethanol/DES (ChCl:EG)). The thermodynamic analysis of the studied system also plays a crucial role in the pharmaceutical industry.

Effect of alkyl chain length and temperature on volumetric, acoustic and apparent molar properties of pyrrolidinium based ionic liquids in acetonitrile

Detailed analysis of volumetric and acoustic properties of the dilute solution of ionic liquids (ILs) and acetonitrile play a significant role in the potential engineering field and process design. Moreover, these studies can provide relevant knowledge about the types and scope of the intermolecular interactions governed between the solute and solvent. In this work, three iodide based pyrolidium ILs, i.e. 1-butyl-1-methyl pyrrolidinium iodide, [BMPY]I and 1-methyl-1-pentyl pyrrolidinium iodide, [PeMPY]I and 1-hexyl-1-methyl pyrrolidinium iodide, [HMPY]I were synthesized and studied their density and sound velocity in acetonitrile as a function of molality in the range of 0.05–0.4 mol·kg−1 and temperature in the range from 293.15 to 328.15 K at atmospheric pressure. The impact of chain length of cation and temperature were premeditated by using well-known volumetric and acoustic factors. In addition, by employing the experimental data, the apparent molar volume (Vϕ), apparent molar isentropic compression (Ks,ϕ), and limiting apparent molar expansion (Eφ∞) were calculated. Further, the apparent molar properties at infinite dilution were examined by using Redlich-Mayer type equations. Furthermore, measured and calculated properties have been analysed to understand the solute-solvent interaction in studied systems. For the studied systems, infinite dilution apparent molar properties were increased with cationic chain length on the ILs, however, decreased with temperature.

Kosmotropic and chaotropic behavior of hydrated ions in aqueous solutions in terms of expansibility and compressibility parameters

Hydrated ions have fundamental applications in chemical and biological processes. Kosmotropic and chaotropic nature of hydrated ions affect the water structure in solutions depending upon their hydrophobicity or hydrophilicity nature. In present study Kosmotropic and chaotropic behavior of hydrated ions have been explained in terms of volumetric and acoustic parameters like apparent molar volume ( V ϕ ), expansibility and compressibility factors for aqueous electrolytic solutions provide useful information about interactions among ions and water molecules. Results of V ϕ showed that SO 4 2− ions due to stronger H-bonding with water molecules are termed as kosmotropes while Cl − and HCO 3 – are chaotropes due to their weaker H-bonding with water molecules. More compressible structure of solutions in the presence of SO 4 2− ions indicated its kosmotropic behavior and comparatively less compressible structure of solutions in the presence of Cl −1 and HCO 3 – ions renders them chaotropes. Results obtained from expansibility factor showed the dominance of electrostatic interactions over hydrophobic hydration of ions at higher temperatures. Greater values of expansibility factor for SO 4 2− ions as compared to Cl −1 and HCO 3 – ions renders them kosmotropic ion while later are termed as chaotropes. Hence, thermo-acoustic parameters could be effectively used to describe the hydrogen bonding character of ionic solutions in terms of kosmotropic and chaotropic behavior of solutions.

Solvation properties of l-lysine and l-arginine in aqueous solutions of 1-heptyl-3-methyl imidazolium tetrafluoroborate [C7mim][BF4]at different temperatures

Thermodynamic and physicochemical properties of lysine and arginine in aqueous and aqueous solution of 1-heptyl-3-methyl imidazolium tetrafluoroborate [C7mim][BF4] have been studied by measuring density and speed of sound data at T = (288.15–308.15 K) under atmospheric pressure. The measured data has been further used to calculate limiting partial molar volume, Vϕ0 , the limiting partial molar compression Kϕ,S0 , and limiting partial molar volumes of transfer, ΔtrVϕ0,and limiting partial molar isentropic compression of transfer ΔtrKϕ,S0 . Furthermore, structure making and structure breaking ability of solute has been discussed by evaluation of apparent molar expansivity, Eϕ0 , Hepler's constant values, ∂Eϕ0∂TP and hydration numbers, nH .

Apparent molar volumes of ILs [EmimNTf2], [BmimNTf2], and [BmmimNTf2] in DEC and PEGMME solvents

Different groups have important influence on the interaction between molecules. In order to understand the effect of group introduction on the molecular interaction in solution, the densities of six diluted solutions including three ionic liquids (ILs) and two organic solvents were measured. The groups include methylene and methyl. The three ILs are 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][NTf2]), 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim][NTf2]), and 1-butyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmmim][NTf2]). The organic solvents are diethyl carbonate (DEC) and propylene glycol monomethyl ether (PEGMME). The measured densities were used to calculate apparent molar volumes, Vϕ/cm3·mol-1, from 293.15 to 328.15 K with ± 0.02 K. Then, the fitting of infinite dilution apparent molar volumes, Vϕ0/cm3·mol-1, were obtained by using the calculated values of apparent molar volumes. The effects of different structures of ILs cations and organic solvents on the apparent molar volume, infinite dilution apparent molar volume, limiting apparent molar expansibility and thermal expansibility coefficient were discussed.

Interaction studies of diglycine with aqueous solutions of sulphathiazole drug at different temperatures

The interactions of diglycine with sulphathiazole drug as a function of temperatures have been studied using volumetric and acoustic parameters. Densities and speeds of sound of diglycine in (0.001, 0.002,0.005, and 0.010) mol·kg-1 aqueous solutions of sulphathiazole drug have been measured at five different temperatures of (288.15,293.15,298.15,303.15 and 308.15) K under 0.1MPa pressure. From density data, the apparent molar volume (Vf), the partial molar volume ( ) and the standard partial molar volume of transfer ( ) for glycine from water to aqueous sulphathiazole solutions have been calculated. Partial molar isentropic compression and partial molar isentropic compression of transfer ( ) have been calculated from the speed of sound data. Transfer parameters by using cosphere overlap model have been explained from the point of view of concentration dependence of solute-solute and solute-solvent interactions. To draw the conclusion from the volumetric and acoustic data, limiting apparent molar expansion , as well as hydration numbers, have been studied. The calculated values of thermal expansion coefficient, , have small and positive values. All of these derived or calculated parameters are explained to understand the solvation behavior, mixing aspects and various types of interactions born in the ternary solutions of (drug + water + dipeptide) due to change in structure. We have also attempted to examine the temperature and concentration dependence of such interactions.

Evaluation of possible interactions for ionic liquids [Emim][HSO4] and [Bmim][BF4] in aqueous sorbitol solutions at T = (293.15–313.15) K by volumetric data

Our systematic volumetric studies on the aqueous solutions containing ionic liquids and carbohydrates is followed in this research by consideration of the ternary (1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium hydrogen sulfate + sorbitol + water) mixtures. For this purpose, via the measured density data, apparent molar volumes, their values at infinite dilution and apparent molar expansibility for these ionic liquids (ILs) in aqueous sorbitol solutions have been calculated. By means of these information, as where as possible, solute =solvent and solute-solute interactions in these systems are discussed. Hydrophilic–hydrophobic hydrophobic–ionic and hydrophobic–hydrophobic interactions are governing in the considered ternary solutions. Both ionic liquids act as structure maker in these solutions.