Partial Molar Expansibilities Research Articles

Volumetric Investigations on Molecular Interactions of Glycine/l-alanine in Aqueous Citric Acid Solutions at Different Temperatures

Apparent molar volumes (phi_{V}) of glycine/l-alanine in water and in aqueous citric acid (CA) solutions of varying concentrations, i.e. (0.05, 0.10, 0.20, 0.30, 0.40 and 0.50) mol·kg−1 were determined from density measurements at temperatures T = (288.15, 298.15, 308.15, 310.15 and 318.15) K and at atmospheric pressure. Limiting partial molar volumes (phi_V^{text{o}}) and their corresponding partial molar volumes of transfer (Delta_{text{tr}} phi_{V} ) have been calculated from the phi_{V} data. The negative Delta_{text{tr}} phi_{V} values obtained for glycine/l-alanine from water to aqueous CA solutions indicate the dominance of hydrophilic–hydrophobic/hydrophobic–hydrophilic and hydrophobic–hydrophobic interactions over ion/hydrophilic–dipolar interactions. Further, pair and triplet interaction coefficients, i.e.(V_{text{AB}} );{text{and}}; (V_{text{ABB}} ) along with hydration number (n_{text{H}} ) have also been calculated. The effect of temperature on the volumetric properties of glycine/l-alanine in water and in aqueous CA solutions has been determined from the limiting partial molar expansibilities (partial phi_{V}^{text{o}} /partial T)_{p} and their second-order derivative (partial^{2} phi_{V}^{text{o}} /partial T^{2} )_{{P}}. The apparent specific volumes (nu_{phi} ) for glycine and l-alanine tend to approach sweet taste behavior both in the presence of water and in aqueous CA solutions. The nu_{phi} values for glycine/l-alanine increase with increase in concentration of CA at all temperatures studied. This reveals that CA helps in enhancing the sweet taste behavior of glycine/l-alanine which also supports the dominance of hydrophobic–hydrophobic interactions.

Temperature dependent solution properties of amino acids in colloidal solutions

Volumetric and acoustic studies of amino acids (l‑aspartic acid and l‑serine) in water and in aqueous cetyl trimethyl ammonium bromide (CTAB) solutions were carried out to understand intermolecular interactions in aqueous solutions of amino acids and in colloidal solutions containing cationic micelles. Density and sound velocity of amino acids solutions of different concentrations in water and in colloidal solutions of CTAB were measured at different temperatures (303.15 K–313.15 K). Volumetric and acoustic parameters like apparent and partial molar volume (Vφ and Vφo), expansibility factor (Eφo), transfer volume, compressibility factors (Kφ and Kφo) and intermolecular free length (Lf) were calculated using measured density and sound velocity data of amino acids solutions. Positive values of Vφ and negative values of Kφ are indicative of strong intermolecular electrostatic interactions among ions of amino acids and water molecules. Presence of CTAB molecules in micellar form in amino acids solutions causes an overall increase in the degree of intermolecular interactions among components of solutions. Moreover, positive values of expansibility factor showed the structure making behavior of amino acids both in water and in aqueous CTAB solutions.

Temperature and concentration dependence towards physicochemical and FTIR spectral studies of glycine, L-alanine and L-valine in aqueous solutions of nortriptyline hydrochloride

Apparent and partial molar properties for glycine, L-alanine and L-valine in aqueous solutions (0.025–0.075) mol·kg−1 of drug NTPH (nortriptyline hydrochloride) have been reported in the present study at intervals of 5 K from temperature 288.15 K to 308.15 K and at experimental pressure of p=0.1 MPa. Different parameters viz. transfer partial molar properties, hydration numbers (nH), partial molar expansibility (E∅0), isobaric thermal expansion coefficient (α) and Hepler’s constant, calculated by using the experimental data of density (ρ) and ultrasonic speeds (u) predict that the solute-solvent interactions are dominating in these ternary systems. The linear variation of V∅0 with the number of carbon atoms in the alkyl chain of amino acids has been utilized to calculate the contribution of the charged end groups NH3+,COO-, (CH2) group and other alkyl chains of the amino acids to V∅0. Pair and triplet interaction coefficients determined from ΔV∅0 and ΔK∅,s0 values using McMillan-Mayer theory indicate the dominance of pairwise interactions in the studied ternary mixtures. The hydration number (nH) comes out to be positive suggesting strong dehydration effect of NTPH. FTIR spectra have been recorded for the mixtures of amino acids in aqueous solutions of NTPH. The decrease in wave number of N–H stretching band also suggests the structural changes in these systems.

Structure Breaking/Making Property of Acefylline Piperazine in Aqueous, Aqueous Methanol, and Aqueous Ethylene Glycol Systems

Densities of acefylline piperazine (AP) in aqueous, aqueous methanol, and aqueous ethylene glycol (10% v/v) systems are determined in the concentration range 0.04-0.14±0.001 mol/dm3 at different temperatures (298.15-318.15 K) with the interval of 5 K. The apparent molar volume (φv), the partial molar volume $$(\phi_v^0)$$ , and the ion-ion interaction parameter (Sv) are calculated using the Masson equation. Partial molar expansibilities $$(\phi_E^0)$$ , which indicate the presence or absence of the caging or packing effect, are also evaluated and discussed. The results are interpreted in terms of solute-solvent and solute-solute interactions of AP in aqueous, aqueous methanol, and aqueous ethylene glycol systems. The structure-breaking and structure-making properties of AP are inferred by the sign of Hepler′s criterion $$(\partial^2\phi_v^0/\partial{T}^2)_p$$ , i.e. the second derivative of the partial molar volume with respect to the temperature at the constant pressure.

Interaction Between an Active Pharmaceutical Ingredient Ionic Liquid Benzalkonium Salicylate and Small Biomolecules in Aqueous Solution: UV Absorption, Conductivity, and Volumetric Study

UV absorption spectroscopy, electrical conductivity and density experiments have been used to investigate the interactions of some small biomolecules (amino acids/dipeptides) with an active pharmaceutical ingredient in ionic liquid form (API-IL), benzalkonium salicylate (BaSal), in aqueous solution. A number of useful parameters, such as critical micellar concentration (cmc), aggregation number (Nagg) and limiting molar conductivity (Λ0) of BaSal, standard partial molar volumes (\(V_{2,\phi }^{ \circ }\)), corresponding volumes of transfer from water to aqueous BaSal solutions (ΔtrVo), standard partial molar expansibilities (\(E_{\phi }^{ \circ }\)), hydration number (nH) of small biomolecules, as well as the binding constants (Kb) for small biomolecule–BaSal complexes have been evaluated. The dependence of the properties on concentration, temperature and alkyl chain length of amino acids/dipeptides is examined. The results are used to identify the solute–solvent physicochemical interactions occurring in the studied systems.

Effect of temperature on thermo-acoustical parameters of arginine in colloidal solutions

Volumetric and acoustic studies of l‑arginine in water and in aqueous sodium dodecyl sulphate (SDS) solutions were carried out to understand intermolecular interactions in solutions of arginine with water and colloidal solutions containing anionic micelles. Density and ultrasonic velocity data for arginine in water and in aqueous colloidal solutions were measured over a temperature range (288.15 K–308.15 K). The experimental data have been used to calculate apparent and partial molar volume (Φv, Φvο), apparent and partial molar compressibility (Φk, Φko), transfer volume (Φνto), partial molar expansibility (ΦE°), acoustic impedance (Z) and relative association (τ) etc. to comprehend inter and intra molecular interactions. The above mentioned parameters have been used to explore the arginine-surfactant interactions among ions of arginine and water molecules. The trends of transfer volumes have been interpreted by the cosphere overlap model. Moreover, the expansibility factor showed the structure making the behavior of arginine both in water and in aqueous SDS solutions.

Molecular interactions of some amino acids in aqueous 1-butyl-3-methylimidazolium bromide solutions at different temperatures: A volumetric approach

Abstract Apparent molar volumes, V ∅ of amino acids i.e. glycine, l -alanine, l -serine, l -threonine and DL- α -aminobutyric acid in pure water and in aqueous solutions of imidazolium based ionic liquid, 1-butyl-3-methylimidazolium bromide, [ BMIm ] [ Br ] were determined from precise density measurements at temperatures T = (288.15–318.15) K and at atmospheric pressure. Partial molar volumes V 2 o and partial molar volumes of transfer, Δ tr V 2 o of amino acids in aqueous [ BMIm ] [ Br ] solutions have been obtained from the V ∅ data. The V 2 o values follow the order: l -threonine > DL- α -aminobutyric acid > l -serine > l -alanine > glycine. Positive Δ tr V 2 o values for all the studied amino acids indicate the dominance of hydrophilic-ionic interactions between amino acids and [ BMIm ] [ Br ] . The partial molar expansibilities ( ∂ V 2 o / ∂ T ) P and their second order derivatives ( ∂ 2 V 2 o / ∂ T 2 ) P , volumetric interaction parameters, V AB and V ABB , hydration number, n H have been calculated. The charged end groups, V 2 o ( NH 3 + , COO - ) , side chain contributions of the amino acids, V 2 o ( R ) and apparent specific volume, v ∅ have also been obtained from V 2 o and V ∅ data. The results have been interpreted in terms of possible molecular interactions.

Analysing the molecular interactions of sucrose in aqueous triammonium citrate and trilithium citrate solutions at different temperatures T = (288.15–318.15) K through volumetric and ultrasonic investigations

The density (ρ) and speed of sound (u) measurements at T = (288.15–318.15) K and experimental pressure p = 0.1 MPa is used for determining the interactions of citrate salts i.e. trilithium citrate (TLC) and triammonium citrate (TAC) with sucrose at different concentrations and different temperatures. The experimental values of density and speed of sound has been used for calculating the apparent molar volumes (Vϕ), partial molar volumes (Vϕo) and partial molar volumes of transfer (ΔVϕo), partial molar expansion coefficients (∂Eϕo/∂T)p, apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression(Kϕ,so), partial molar isentropic compression of transfer (ΔKϕ,so) for sucrose in (0.0, 0.2, 0.4, 0.6) mol·kg−1 aqueous TAC and TLC solutions at temperatures in the range (288.15–318.15) K at experimental pressure p = 0.1 MPa. The pair and triplet interaction coefficients have been calculated from partial molar volumes of transfer and partial molar isentropic compression of transfer.

Study of Intermolecular Interactions of CTAB with Amino Acids at Different Temperatures: A Multi Technique Approach

Abstract The densities, ρ, viscosities, η and specific conductivities κ, of (0.0002, 0.0004, 0.0006 and 0.0008 m) CTAB in 0.1 m aqueous valine, leucine and isoleucine were measured at different temperatures. The measured data were used to calculate various useful thermodynamic parameters. A complete characterization of any mixture can be performed by means of these thermodynamic properties. The apparent molar volume, ϕv , partial molar volume, ϕ v 0 $\phi _v^0$ and partial molar isobaric expansibilities, ϕ E 0 , $\phi _E^0,$ were calculated using density data. The viscosity data were analyzed using Jones–Dole equation to obtain viscosity coefficients, A- and B-, free energy of activation per mole of solvent, Δμ 1°∗, and solute, Δμ 2°∗, enthalpy, ΔH ∗ and entropy, ΔS ∗ of activation of viscous flow. Measuring the changes in these properties has been found to be an excellent qualitative and quantitative way to obtain information regarding the molecular structure and intermolecular interactions occurring in these mixtures. Various structure-making/breaking ability of solute (cetyltrimethylammonium bromide) in presence of aqueous amino acid solutions were discussed. In addition, fluorescence study using pyrene as a photophysical probe has been carried out, the results of which support the conclusions obtained from other techniques.

Studies on the interactions of some small biomolecules with antibacterial drug benzethonium chloride and its active pharmaceutical ingredient ionic liquid (API-IL) benzethonium L-proline at varying temperatures

From the conductivity, density and spectroscopy measurements, the interactions of benzethonium chloride ([BTC]) and its active pharmaceutical ingredient in ionic liquid format benzethonium L-proline ([BT][PRO]) with some amino acids and glycyl dipeptides have been examined. A number of useful parameters, such as standard partial molar volume (V2, ϕo), partial molar transfer volume (ΔtVo), standard partial molar expansibility (Eϕo) of these small biomolecules, critical micelle concentration (cmc), aggregation number (Nagg), thermodynamic micellization parameters of [BTC]/[BT][PRO], as well as binding constant for small biomolecule-drug complex have been evaluated. Group contributions of charged end group (NH3+, COO−), CH2 and (CH2CONH) groups of amino acids/dipeptides to V2, ϕo values have also been perceived. These parameters are helpful to study the structure making capacity of small biomolecules, solvation behavior of [BTC]/[BT][PRO] and various interactions present in the studied ternary solution. The interaction difference of [BTC] and [BT][PRO] with small biomolecules was studied.

Density and volumetric properties of the aqueous solutions of urea at temperatures from T = (278 to 333) K and pressures up to 100 MPa

Abstract This paper highlights the values of densities of aqueous solutions of urea in the concentration range m (from 0.1809 to 12.801) mol·kg−1 at T = (278.15, 288.15, 298.15, 308.15, 323.15 and 333.15) K and at p = (0.101, 10, 25, 50, 75 and 100) MPa. The densities were also measured for dilute aqueous solutions m (from 0.093 to 2.505) mol·kg−1 with temperature from 274.15 to 283.15 K, with increment of 1 K at atmospheric pressure, in order to study the effect of urea on the temperature of the maximum water density. Volumetric properties calculated from the density, such as apparent molar volumes of urea, Vɸ,2, molar isothermal compressions, KT,m, and molar isobaric thermal expansions, EP,m, of solution are considered depending on concentration, temperature and pressure. Also, certain volumetric characteristics for infinitely diluted urea in water were obtained: the limiting partial molar volumes, V 2 ∞ ; limiting partial molar isothermal compressions, K T , 2 ∞ ; and limiting partial molar isobaric thermal expansions, E P , 2 ∞ . Obtained results are discussed from the standpoint of solute – solute and solute – solvent interactions. With the help of various approaches based on volumetric characteristics, the character of the disturbing effect of urea on the water structure was described.

Interactions of glycine with aqueous solutions of sodium phosphate buffer at T = (288.15, 293.15, 298.15, 303.15, 308.15, 310.15, 313.15, 318.15, 323.15 and 328.15) K: Volumetric and UV absorption studies

Interactions of glycine with sodium phosphate buffer have been investigated by volumetric and UV absorption studies. Densities have been measured for glycine in water of pH=(1.00, 7.40 and 13.40) and in 0.1M, 0.5M and 1M aqueous sodium phosphate buffer (NaPB) solutions as a function of concentration at T=(288.15 to 328.15) K and at pH=(1.00, 7.40 and 13.40) by using digital density meter. Apparent molar volumes (V∅) and partial molar volumes (V2o) obtained from these density data have been used to calculate partial molar volumes of transfer (∆trV2o) from water to aqueous sodium phosphate buffer solutions, which are positive for zwitterionic and deprotonated form of glycine. Interaction coefficients have been obtained from McMillan-Mayer's approach. Effect of temperature on these thermodynamic properties have been studied by determining the partial molar expansibilities (∂V2o/∂T)P at infinite dilution and their second order derivative (∂2V2o/∂T2)P at different temperatures and at pH=(1.00, 7.40 and 13.40). Hydration number (nH) of glycine at pH7.40 have been determined from the V2o data. The results have been rationalized in terms of various interactions taking place in these systems. Further, absorption spectra have also been recorded for the present system with the help of UV–visible spectrophotometer at 298.15K which is helpful in interpreting the possible molecular interactions between glycine and NaPB.

Molecular Interactions Investigation of L-Histidine in Water and in Aqueous Citric Acid at Different Temperatures Using Volumetric and Acoustic Methods

Abstract Densities, ρ and ultrasonic speeds, u of L-histidine (0.02–0.12 mol·kg−1) in water and 0.1 mol·kg−1 aqueous citric acid solutions were measured over the temperature range (298.15–313.15) K with interval of 5 K at atmospheric pressure. From these experimental data apparent molar volume Φ V , limiting apparent molar volume Φ V O and the slope SV , partial molar expansibilities Φ E O , Hepler’s constant, adiabatic compressibility β, transfer volume Φ V, tr O , intermolecular free length (Lf ), specific acoustic impedance (Z) and molar compressibility (W) were calculated. The results are interpreted in terms of solute–solute and solute–solvent interactions in these systems. It has also been observed that L-histidine act as structure maker in water and aqueous citric acid.

Densities and Volumetric Properties of Aqueous Solutions of {Water (1) + N-Methylurea (2)} Mixtures at Temperatures of 274.15–333.15 K and at Pressures up to 100 MPa

Densities of the mixture {water (1) + N- methylurea (2)} in the concentration range to mole fraction x2 = 0.07071 (or to the solution molality concentration m2 = 4.22335 mol·kg–1) at atmospheric pressure in the temperature range from 274.15 to 333.15 K and compression k = ΔV/V0 at pressures to 100 MPa (10, 25, 50, 75, and 100) in the temperature range from 278.15 to 323.15 K (278.15, 288.15, 288.15, 308.15, 323.15) in the same concentration range were calculated in this study. The apparent molar volumes of N-methylurea Vϕ,2 and the partial molar volumes of both components V̅1 and V̅2 in the mixture, molar isothermal compressibilities KT,m, molar isobaric thermal expansions EP,m, and isochoric coefficients of thermal pressure β of the mixture were calculated. Moreover, volumetric measures for the infinitely dilute solution of N-methylurea solution were calculated: limiting partial molar volumes V̅2∞, the limiting partial molar isothermal compressibilities K̅T,2∞, and the limiting partial molar isobaric thermal expansions E̅P,2∞. The results obtained are discussed from the point of view of solute–solvent and solute–solute interactions.

Study of solute-solute and solute-solvent interactions of streptomycin sulphate in aqueous-l-asparagine/l-glutamine solutions at different temperatures by using physicochemical methods

The densities, ρ of streptomycin sulphate in water and in aqueous l-asparagine/l-glutamine (1% and 2% l-asparagine/l-glutamine in water, w/w) solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K; and ultrasonic speeds, u and viscosities, η of these solutions were measured at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The ρ, u and η data have been used to calculate apparent molar volumes, Vϕ, limiting apparent molar volumes, Vϕ°, apparent molar compressibilities, Ks,ϕ, limiting apparent molar compressibilities, Ks,ϕ°, transfer volumes, Vϕ,tr°, transfer compressibilities, Ks,ϕ,tr° and limiting partial molar expansibilities, Eϕ°. The viscosity data have been used to determine Falkenhagen Coefficients, A and Jones-Dole coefficients, B. These parameters have been discussed in terms of solute-solute and solute-solvent interactions prevailing in these solutions. The structure making/breaking ability of streptomycin sulphate in these solutions is also discussed. Furthermore, the Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, entropies, ΔSο and enthalpies, ΔHο of activation of viscous flow were also calculated and discussed in terms of transition state theory.

Properties of L-ascorbic acid in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures

Using density and sound velocity partial molar volumes, partial molar adiabatic compressibilities, partial molar expansibilities and structure of L-ascorbic acid have been determined in water and aqueous mixtures of D-glucose and D-fructose at different concentrations and temperatures. Masson’s equation was used to analyze the measured data. The obtained parameters have been interpreted in terms of solute–solute and solute–solvent interactions. It is found that the L-ascorbic acid acts as structure breaker in water as well in binary studied mixtures.

Investigation on Temperature-Dependent Volumetric and Acoustical Properties of Homologous Series of Glycols in Aqueous Sorbitol Solutions

In the present study, the combination of volumetric and acoustical studies is used to investigate the interactions of ethylene glycol, diethylene glycol, and triethylene glycol with sorbitol as a function of temperature. Densities and ultrasonic velocities of ethylene, diethylene, and triethylene glycol in (0.00, 0.01, 0.03, 0.05) mol·kg–1 aqueous solutions of sorbitol have been measured at temperatures T = (288.15, 298.15, 308.15, 318.15) K and experimental pressure p = 0.1 MPa. With the help of density data, the apparent molar volume Vϕ, the partial molar volume Vϕo, and the partial molar volumes of transfer ΔVϕo, from water to aqueous sorbitol solutions have been computed. The values for partial molar expansibility (∂Vϕ0/∂T)p and second order derivative (∂2Vϕ0/∂T2)p have also been determined. From ultrasonic velocity values, apparent molar isentropic compression Kϕ,s, partial molar isentropic compression Kϕ,so, and partial molar isentropic compression of transfer ΔKϕ,so, are evaluated. The computed val...

Effect of concentration and temperature on the interactions between saline soil salts and nitro phosphate fertilizer under atmospheric pressure: A thermo-acoustic approach

A decrease in the ability of the plants to absorb nutrients usually takes place in saline soils. Application of fertilizers corrects nutrients deficiencies and decreases the adverse effects of saline salts on the plants. The present work is aimed to study the interactions of fertilizer with saline salts in aqueous solutions to explore the role of fertilizer on soil fertility by controlling soil salinity in terms of fertilizer-salt interactions. Density and speed of sound of nitrophosphate in water and in saline salts solutions of different concentrations has been measured at different temperatures. Thermo acoustical parameters like apparent and partial molar volume, partial molar expansibility and Hepler's constant, compressibility factor and intermolecular free length have been calculated. Positive values of apparent molar volume (VФ) and negative values of apparent and partial molar compressibility (KФ and Kфo)of fertilizer in solutions showed strong intermolecular interactions in solutions. Positive values of Hepler's constant indicate the structure making behavior of fertilizer in water and in saline salt solutions.

Molecular interaction studies of l-alanine and l-phenylalanine in water and in aqueous citric acid at different temperatures using volumetric, viscosity and ultrasonic methods

Densities, ultrasonic speeds and viscosities of l-alanine and l-phenylalanine in water and in 0.1mol·kg−1 aqueous citric acid solutions were measured over the temperature range (298.15 to 313.15)K with interval of 5K at atmospheric pressure. From these experimental data apparent molar volume, limiting apparent molar volume and the slope, partial molar expansibilities, adiabatic compressibility, transfer volume, Falkenhagen coefficient, Jone-Dole's coefficient, the temperature derivative of Jone-Dole's coefficient, intermolecular free length, specific acoustic impedance, and molar compressibility were calculated. The results are interpreted in terms of solute – solute and solute-solvent interactions in these systems. It has also been observed that l-alanine acts as a structure breaker whereas l-phenylalanine acts as a structure maker in aqueous citric acid.

Volumetric and UV Absorption Studies on Interactions of an Active Pharmaceutical Ingredient Ionic Liquid (API-IL) Domiphen l-Proline with Amino Acids and Glycyl Dipeptides in Aqueous Solution at T = (293.15–308.15) K

Novel ionic liquids containing the domiphen cation, as an active pharmaceutical ingredient ionic liquid (API-IL), domiphen l-proline ([DOM][l-PRO]) was synthesized and the interactions of domiphen l-proline with some small biomolecules (amino acids and glycyl dipeptides) were investigated at different temperatures from density and UV–Vis spectroscopy measurements. The apparent molar volumes, standard partial molar volumes, transfer volumes, hydration numbers and partial molar expansibilities of small biomolecules have been calculated. Group contributions of amino acids/dipeptides to the standard partial molar volume were determined and the contributions from the zwitterionic end group (NH3 +, COO−), CH2 and (CH2CONH) groups have been obtained. The binding constants between small biomolecules and [DOM][l-PRO] were also obtained. A detailed insight into the physicochemical interactions in the ternary systems was obtained through the perusal of these parameters. Compared with [DOM][Br], [DOM][l-PRO] interacts with small biomolecules weakly.