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The solubilities of formononetin and daidzein in methanol, ethanol, n-propanol, isopropanol and acetone were measured by a static equilibrium method at temperatures range from 293.2 to 323.2 K. The solubilities of formononetin and daidzein increased with rising temperature. At a given temperature, the solubility expressed in mole fraction was recorded highest in acetone (e. g., 5.2735 × 10–4 for formononetin and 7.4678 × 10 – 4 for daidzein at T = 293.2 K, respectively.) followed by n-propanol, isopropanol , ethanol, and methanol, and the solubility in different solvents mainly depended on the polarity and hydrogen-bond acceptor (HBA) basicity of the solvents. Moreover, the experimental solubility data in all solvents could be reasonably correlated by ideal model, the modified Apelblat equation, λh equation and van't Hoff equation (the relative average deviations (RAD)were all < 3.29%.), wherein the modified Apelblat model showed the best correlation (RAD < 2.94% ). The dissolution thermodynamic properties, including enthalpy, entropy and Gibbs energy of formononetin and daidzein in the dissolution process were evaluated using the van't Hoff equation. In addition, the COSMO–RS model was also applied to predict the solubilities of the two solutes and take insight into the intrinsic solvation mechanism within the systems, and the results confirmed that daidzein had relative higher values of solubility in the solvents as compared to formononetin due to the stronger hydrogen-bond interaction between daidzein and the solvents. The COSMO–RS model showed relative good agreement with the experimental values in tested solvents, especially in alcohols, and could provide excellent qualitative agreement with experimental dissolution behavior both for temperature dependence and for effect of molecular structures of the solutes. [ABSTRACT FROM AUTHOR]

The solubility of chrysin in N , N -dimethylformamide (DMF), acetone, ethyl acetate (EA), n -butanol, isopropanol, n -propanol, ethanol, methanol, n -hexane, and water was measured by using the static equilibrium method or the dynamic method at temperatures ranging from 293.2 to 333.2 K. Chrysin shows the easiest solvation in the dipolar aprotic solvents, followed by the polar protic solvents (alcohols), and shows poor solvation in the apolar aprotic solvents (hexane) and the strong polar water. The solubility of chrysin increases with rising temperature. The inherent microscopic solvation mechanisms were investigated qualitatively and quantitatively using a combination of the KAT-LSER model as well as σ-profile theory and molecular interaction energies calculated by COSMO–RS model. The results show the solvation process of chrysin in the different solvents is a complex process which depends on the synergistic effects of multiple molecular interactions between the solute and solvent together with the solvent and solvent. Moreover, the experimental solubility data in all solvents could be reasonably correlated by the modified Apelblat equation, λh equation, van't Hoff equation, Wilson model, and NRTL model, whereas the NRTL model and the modified Apelblat equation showed the most satisfactory fitting results. The dissolution thermodynamic properties, including enthalpy, entropy and Gibbs energy of chrysin in the dissolution process were evaluated using the van't Hoff equation. Moreover, the overall dissolution trend and the temperature-dependence of experimental solubility of chrysin in the different classes of solvents can be predicted correctly by the COSMO–RS model. Unlabelled Image • The solubility of chrysin in different classes of solvents was measured. • Solvation capacity for chrysin: dipolar aprotic > polar protic > apolar solvents. • Solvation depends on the synergistic effects of multiple intermolecular interactions. • Solute-solvent van der Waals and hydrogen bond interactions favor on the solvation. • Hydrophobic and solvent-solvent interactions are unfavorable for the solvation. [ABSTRACT FROM AUTHOR]