Solubility, Preferential Solvation, and Solvent Effect of Micoflavin in Aqueous Mixtures of Dimethylsulfoxide, Isopropanol, Propylene Glycol, and Ethanol

摘要

The saturated thermodynamic solubilities of micoflavin in four mixtures of dimethyl sulfoxide (DMSO, 1) + water (2), isopropanol (1) + water (2), propylene glycol (PG, 1) + water (2), and ethanol (1) + water (2) are reported in this contribution. All experiments were carried out via the saturation shake-flask technique at temperatures from 278.15/293.15 to 318.15 K. The solubility data were maximum in neat DMSO (isopropanol, PG, or ethanol) for the four mixtures studied. The micoflavin solubility was mathematically well described through the Jouyban-Acree model, attaining root-mean-square deviation values lower than 3.68 x 10(-4) and relative average deviation values lower than 6.27%. The local mole fractions of DMSO (isopropanol, ethanol, PG and water) around micoflavin were quantitatively studied via the method of inverse Kirkwood-Buff integrals on the basis of the solubility data determined. The solvation of micoflavin was preferential by water for these mixtures in the water-rich compositions, whereas in the cosolvent-rich and intermediate compositions, the solvation of micoflavin was preferential by DMSO isopropanol, PG, or ethanol) in the DMSO (isopropanol, PG, or ethanol) + water mixtures. In addition, the cosolvency effect was reorganized by considering the Kamlet and Taft linear solvation energy relationships, and the relative importance of the solvent- solvent and solvent-solute interactions was distinguished. Results indicated that the micoflavin solubility variation was governed by the cavity term in the DMSO + water solution and the cavity and a terms in the aqueous solutions of PG, isopropanol, and ethanol.