This study describes the thermodynamics of dissolution of flavonoid naringin in different aqueous solutions of dimethyl sulfoxide (DMSO) containing 0-100% (w/w) under atmospheric pressure and over a temperature range of 298.15 to 325.15 K. The temperature dependence of solubility of naringin was analyzed using the modified Apelblat equation model, ideal model, and the lH equation model. In a mean harmonic temperature, the dissolution thermodynamic parameters of naringin containing DG sol , DH sol and DS sol were also calculated. Furthermore, the effects of solvent composition on the solubility of this flavonoid were analyzed in terms of Hildebrand's solubility parameter (d H ) and Kamlet, Abboud and Taft (KAT) solvatochromic parameters (a, b, and p*). Finally, the preferential solvation parameters of the flavonoid naringin by DMSO (dx DMSO,S ) were determined from experimental solubility data using the inverse Kirkwood-Buff integrals (IKBIs). It was found that water preferentially solvates naringin in waterrich mixtures while DMSO forms local solvation shells in compositions from 50% (w/w) or x DMSO ¼ 0.19 up to pure co-solvent. Moreover, the structure of solvation shells of naringin in the under study mixtures was obtained by molecular dynamics (MD) simulations. The computational results showed that in the compositions x DMSO > 0.20, the probability of presence of the DMSO molecules in vicinity of naringin is more than water molecules. These findings are compatible with the available IKBI data.

The formation constants of the species formed in the systems H+ + Mo(VI) + aspartic and glutamic acids and H+ + aspartic and glutamic acids have been determined in different aqueous solutions of methanol [(0 to 40) % v/v] at 25 °C and constant ionic strength (0.1 mol·dm−3 sodium perchlorate), using a combination of spectrophotometric and potentiometric techniques. The composition of the complexes was determined by the continuous variations method. It was shown that molybdenum(VI) forms a mononuclear 1:1 complex with the amino acids of the type MoO3L2− at pH 5.8. The protonation and formation constants in various media were analyzed in terms of Kamlet and Taft’s parameters. Single-parameter correlations of the formation constant, K S , versus α (hydrogen-bond donor acidity), β (hydrogen-bond accepter basicity), and π* (dipolarity/polarizability) are poor in all solutions, but multiparameter correlations represent significant improvements with regard to the single-parameter models. Linear correlation is observed when the experimental log K S values are plotted versus the calculated ones, while all the Kamlet and Taft’s parameters are considered. Finally, the results are discussed in terms of the effect of solvent on protonation and complexation.

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Kamlet−Abboud−Taft (KAT) solvatochromic parameters (α, β, and π*), as well as the Reichardt's polarity scale (E T (30)), were measured from ultraviolet−visible (UV−vis) absorption spectral shift of three indicator solutes namely 4nitroaniline, N,N-dimethyl-p-nitroaniline, and the betaine dye 4-(2,4,6-triphenylpyridinium-1-yl)-2,6-diphenylphenolate. These measurements were done within the whole mole fraction range of the binary mixture of green solvents N-formylmorpholine with water, ethanol, 1-propanol, 2-propanol, 1-butanol, and ethyl acetate at room temperature (298.15 ± 0.1 K). The Redlich−Kister model was employed to demonstrate the effect of solvent composition on the solvatochromic parameters obtained in the mixtures understudy. The data of E T obtained for the indicator dyes in different mole fractions (0.0−1.0) of the binary mixtures were analyzed to investigate their preferential solvation in terms of both the solute−solvent and the solvent−solvent interactions. The solvent exchange model was successfully utilized to calculate preferential solvation parameters. It was found that the solvation shell of the dyes is mainly affected by the solvent−solvent interactions, and all studied systems showed the nonideal behavior.