Journal of Chemical Thermodynamics最新文献

The density (ρ), and refractive index (n_D) of three binary mixtures containing 1-butanol, 2-butanol, and 2-methyl-2-propanol with diethyl phthalate (DEP) were studied over the whole range of composition at different temperatures from 293.15 to 313.15 K, and atmospheric pressure (0.082 MPa). Experimental data were used to calculate the excess molar volumes ($V_m^E$) and deviation in refractive indices ($\Delta n_D$). The experimental density values were used to calculate the partial molar volumes (${\overline{V}}_{m,i}$), apparent molar volumes ($V_{\varnothing ,i}$), partial molar volumes at infinite dilution (${\overline{V}}_{m,i}^{\infty }$), and excess partial molar volumes (${\overline{V}}_{m,i}^E$). A Redlich-Kister type polynomial equation is used with the method of least-squares to set up a correlation between excess molar volumes and deviation in refractive indices, leading to the estimation of binary coefficients and standard errors. Theoretical refractive index values were calculated using seven relations, namely Arago–Biot (A–B), Dale–Gladstone (D–G), Lorentz–Lorenz (L–L), Heller (H), Weiner (W), Newton (Nw) and Eyring and John (E-J). This study examines how composition and temperature affect the variation of parameters in these mixtures, considering molecular interactions. Experimental data and results provide useful information for further thermodynamic studies of alcohol-ester mixtures.

The shake-flask method was used to determine the solubility of sotalol hydrochloride (STL), a cardiovascular drug, in solvents modeling a variety of body media within the temperature range (293.15–313.15) K. In the descending order of the drug solubility the solvents can be arranged as follows: buffer pH 2.0, buffer pH 7.4, 1-octanol, n-hexane. The experimental values of solubility of the drug in aqueous solvents agree well with the calculated values of the pH-solubility profile. The study shows that the maximum solubility of the salt is observed within the pH range from 2.9 to pH_max equal to 6.1. Temperature dependencies of the STL distribution coefficients were obtained in 1-octanol/buffer pH 7.4 and n-hexane/buffer pH 7.4 systems. Since the values of the partition coefficients of hydrophilic STL are low, it was concluded that the diffusion through the lipid biolayer of cell membranes was unfavorable and that the paracellular transport of the drug molecules might prevail. The thermodynamic functions of dissolution and transfer were calculated and discussed taking into account the physicochemical properties of STL and the solvents used.

Density and viscosity of two trifluoromethanesulfonate-based ionic liquids: 1-ethylimidazolium trifluoromethanesulfonate, [Eim][Triflate], and 1-ethylpyridinium trifluoromethanesulfonate, [Epy][Triflate], as well as binary mixtures of these ILs with water or ethanol were measured within the temperature range of 293.15–333.15 K. Measured density data were used to calculate the excess molar volume and the component partial molar volume and the obtained values were fitted using the Redlich-Kister expansion. Variation of viscosity with the binary mixture composition and temperature was modeled using the Jouyban-Acree model. Data on the vapor−liquid equilibrium (VLE) of the respective ionic liquids with water and ethanol were estimated at atmospheric pressure over a wide range of IL concentrations (up to 70 mol% of IL). For the boiling point temperature measurement of four respective binaries, an adapted Siwoloboff procedure was used. To describe VLE of these binary mixtures, ideal vapor phase and real liquid phase behavior were assumed; experimental isobaric t–x data were correlated with the NRTL model.

The difenoconazole solubilities in acetonitrile/acetone/N,N-dimethylformamide (DMF) + water systems were acquired experimentally with the help of the isothermal shake-flask technique. Analysis of X-ray power diffraction revealed that difenoconazole did not exhibit any crystal transition as well as solvate formation. The solubility acquired here was accurately correlated, which yielded relative average deviations (RAD) of ≤4.99 % and a root-mean-square deviation of ≤20.59 × 10⁻⁵ through the Jouyban-Acree and modified van’t Hoff-Jouyban-Acree models Additionally, to explain the solubility behavior at a temperature of 298.15 K, this work examines the acetonitrile/acetone/DMF + water and the previously published methanol/ethanol/isopropanol/PG + water blends utilizing the extended Hildebrand solubility technique. The RAD levels remained below 6.88 %. The dipolarity-polarizability and the solubility parameter of blended solvents exert a substantial impact on the variability of difenoconazole solubility. The preferred solvation of difenoconazole at a temperature of 298.15 K was examined through the inverse Kirkwood-Buff integrals. The solvation parameters’ values of difenoconazole were positive in blends containing methanol, acetone, DMF, ethanol, isopropanol, and acetonitrile with moderate and rich compositions. This indicates that difenoconazole is preferentially solvated by them in above composition ranges. A shift from an enthalpy-driven mechanism to an entropy-driven one was revealed through an analysis of the thermodynamics of the entropy-enthalpy relationship in the dissolution of difenoconazole in blends. Furthermore, the mean local ionization energy, Hirshfeld surface as well as molecular surface electrostatic potential were employed to illustrate the microscopic electrostatic characteristics. The N and N groups in the five-membered ring of difenoconazole molecule are the primary sites for electrophilic attack. The weak contacts of difenoconazole-solvent were demonstrated with the help of a Hirshfeld partition analysis-based independent gradient model.

As the only known equation of state (EOS) with the rigid theoretical foundation, the virial equation of state (VEOS) can be reliable enough to describe real-gas imperfection for low-to-moderate densities when truncated after the second or third virial coefficient. In our previous work, on the basis of the corresponding state principle, the generalized second and third virial coefficient models were proposed for nonpolar, polar and quantum fluids in a wide temperature range. In this work, combined with the ideal heat capacities, the high-temperature performance of the truncated VEOSs was evaluated on derived thermodynamic properties including speed of sound, isobaric heat capacity, entropy and internal energy. The criterion for being “valid” is defined as 1% relative deviation from the multiparameter EOSs, and this work presents the valid density and pressure regions of the truncated VEOSs for the derived thermodynamic properties. The truncated VEOSs have valid densities of the saturated densities below the critical temperatures, and have valid densities that tend to be constant beyond the critical temperatures. The SRK EOS is chosen as the representative of generalized EOSs. By the comparisons with the SRK EOS, the truncated VEOSs show the advantage in stability and universality. The truncated VEOSs can give a reliable extrapolation with wide applicable pressure ranges at high temperatures for nonpolar, polar and quantum fluids. The applicable density regions of the truncated VEOSs for derived thermodynamic properties are recommended to be the valid density regions of the pvT property. The applicable temperature ranges of the truncated VEOSs for derived thermodynamic properties are determined by the temperature ranges of the available ideal heat capacity data.

The solubility of 2-ethoxy-1-naphthoic acid was determined experimentally in 12 pure solvents (methanol, ethanol, n-propanol, i-propanol, i-butanol, n-pentanol, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, acetone and acetonitrile) using the gravimetric method in the temperature range of 278.15 K to 323.15 K at atmospheric pressure. The study found that solubility increased with temperature, with acetone exhibiting the highest solubility and acetonitrile the lowest at 298.15 K. Furthermore, the influence of solvent properties on solubility, such as polarity and dielectric constant, was analyzed, showing a positive correlation. Mathematical models (including modified Apelblat, NRTL, Margules, UNIQUAC and λh models) were employed to analyze the dissolution process, with the modified Apelblat model providing the best fit to the experimental data. Additionally, thermodynamic properties of the dissolution process were obtained using the Van’t Hoff equation, indicating an entropy-increasing process with heat absorption. Overall, this study elucidates the solubility behavior and related mechanisms of 2-ethoxy-1-naphthoic acid in various solvents, providing theoretical support for its application in solution systems.

Ethyl ((1R,2S,5R)-2-isopropyl-5-methylcyclohexane-1-carbonyl) glycinate (Cooling agent WS-5) is an important cooling menthane carboxamide. In this work, the solid–liquid equilibrium data of WS-5 in twelve mono solvents (namely methanol, ethanol, n-propanol, isopropanol, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, acetone, acetonitrile and cyclohexanone) were measured by a laser dynamic method from 278.15 K to 313.15 K under 101.6 ± 1.2 kPa. In the studied temperature range, the solubility of WS-5 correlated positively with temperature. Subsequently, the solubility data were correlated with the van’t Hoff equation, modified Apelblat equation, λh equation, Wilson model, and NRTL model, respectively. It was found that the modified Apelblat equation showed the best fitting performance with the smallest average values of RAD (relative average deviation) and RMSD (root mean square deviation), and the average values of RAD and RMSD were 0.94 % and 0.19 %, respectively. In order to explain the dissolution behavior of WS-5 in different solvents, the intermolecular interactions were analyzed using Hirshfeld surface (HS) analysis and molecular electrostatic potential surface (MEPS). Then, the molecular dynamic (MD) calculation was carried out, and the radial distribution function (RDF) analysis was employed to explain the intermolecular interaction between WS-5 and solvent molecules. Besides, the solvent properties, including polarity, hydrogen bond, cohesive energy, density, and viscosity, were compared to analyze the solid–liquid equilibrium behavior of WS-5. In addition, the thermodynamic properties of dissolution (${\Delta G}_{sol}$, ${\Delta H}_{sol}$ and ${\Delta S}_{sol}$) of WS-5 were calculated, and the results implied that the dissolution process of WS-5 was endothermic and entropy-driven.

In this work the heat capacity $C_{p,m}^o=f\left(T\right)$ of the garnet-structured Na₃Cr₂(AsO₄)₃ was first investigated. Measurements were performed in the range of T = (5 and 323) K using a precise adiabatic vacuum calorimeter. The phase purity and composition homogeneity were verified by X-ray diffraction analysis with Rietveld method calculations and X-ray microanalysis. The $C_{p,m}^o,{\Delta }_0^T{H}_m^0,{\Delta }_0^T{S}_m^{0}and{\Delta }_0^T{G}_m^0$ have been calculated using experimental data from T→0 to 323 K.

We are reporting curcumin-induced synthesis of anisotropic citrate capped Gold nanoparticles (ctGNPs). The techniques such as UV–visible spectroscopy, Raman spectroscopy, FT-IR, X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) were used to characterize the nanoparticles. The synthetic route shows the formation of an anisotropic gold nanostructure consisting of spherical, triangles, hexagonals, and a low-yield rod with an aspect ratio ranging from 4.2 to 8.5. Curcumin-derived ctGNPs shows stability at different physiological conditions and better biocompatibility. Synthesized nanoparticles are found non-toxic towards eukaryotic cells but more effective against the cancer cell lines HeLa and MCF-7. The interaction of these synthesized nanoparticles with human telomeric G-quadruplex (GQ) DNA was studied using different physiochemical methods. The spectroscopic studies show that synthesized nanoparticles have stronger binding affinity towards telomeric GQ as compared to ds DNA through Van der Waals and H-bonding interactions. Thermodynamic interpretation reveals that the formation of the complex between the telomeric GQ and ctGNPs are enthalpy driven and entropy unfavourable process, resulting in motion freezing and, eventually, AuNP aggregation. Thus, our study shows a new approach to understand the interaction of telomeric G-quadruplexes with gold nanoparticles generated via the green route.

In this work, n-hexane, cyclohexane and 2-methylpentane were selected to represent linear-alkane, cycloalkane and branched-alkane, respectively. Based on the dynamic light method (DLS), the viscosity, interfacial tension and diffusion coefficient of n-hexane/CO₂, cyclohexane/CO₂ and 2-methylpentane/CO₂ systems under saturation condition were measured in order to explore the change trend of thermophysical properties of the systems with the same carbon atom number but different molecular structures. The experiments were conducted at the temperatures of 303, 343 and 383 K and at pressures up to 5.64 MPa. The expanded uncertainties（k = 2）of dynamic viscosity, interfacial tension and diffusion coefficient were 3 %, 3 % and 4.4 % respectively. The experimental results show that n-hexane and 2-methylpentane with similar molecular structure have more similar value of the properties. The effects of different alkane structures on system viscosity, interfacial tension, and diffusion coefficient were explained at the molecular level through radial distribution function, interface thickness, and CO₂ coordination number. At 303.15 K and 4 MPa, the peak radial distribution function of CO₂/cyclohexane is 1.845, which is greater than that of CO₂/n-hexane and CO₂/2-methylpentane molecules. It has been proven that the arrangement of CO₂/cyclohexane is more orderly, resulting in higher viscosity and lower diffusion coefficient of the system. The interface thickness of CO₂/cyclohexane is 6.13 nm, which is smaller than CO₂/n-hexane (7.53 nm) and CO₂/2-methylpentane (6.3 nm). The smaller the interface thickness, the more compact the structure, the stronger the intermolecular forces, and the greater the interfacial tension. At 303.15 K and 2 MPa, the number of CO₂ coordination sites within 1 nm around liquid phase alkanes is 3.96, which is smaller than 4.78 for cyclohexane and 6.62 for 2-methylpentane. Prove that the coordination number is directly proportional to the diffusion coefficient and inversely proportional to viscosity and interfacial tension.