Uridine in twelve pure solvents: Equilibrium solubility, thermodynamic analysis and molecular simulation

Abstract in this work, the solubility of uridine in twelve neat solvents was investigated by using experimental laser monitoring method and molecular dynamic (MD) simulation analysis approach. The experimental solubility data of uridine in twelve neat solvents, including methanol, 2-methoxyethanol, ethanol, 2-ethoxyethanol, n-propanol, 2-propoxyethanol, isopropanol, n-butanol, 2-butoxyethanol, ethylene glycol, N, N-dimethylformamide (DMF) and water, was measured at temperature range of (278.15 K–323.15 K) under atmospheric pressure. The solubility of uridine was sensitive to temperature in tested solvents, namely, increased monotonously with rising temperature. The order of uridine solubility at 298.15 K in selected solvents is DMF (0.1780) > water (0.04061) > 2-methoxyethanol (0.01565) > ethylene glycol (0.01399) >2-ethoxyethanol (0.006413) > methanol (0.003195) > 2-propoxyethanol (0.003005) > 2-butoxyethanol (0.002241) > isopropanol (0.001238) > ethanol (0.001086) > n-propanol (0.001047) > n-butanol (0.0009806). the measurement solubility data was correlated by NRTL model, NRTL-SAC model, UNIQUAC model, λh equation and Apelblat equation, respectively. The derived apparent thermodynamic parameters (ΔdisGo, ΔdisHo, ΔdisSo, ζH, ζTS) shown an entropy-driven, endothermic and spontaneous process of dissolution of uridine in all chosen solvents, and the main contribution of ΔdisGo comes from the positive enthalpy. Hansen solubility parameters (HSPs) were employed to reveal the solubility phenomenon of uridine in selected solvents. Furthermore, the results of molecular dynamic simulation revealed using radial distribution function (RDF) analysis, which indicated that interactions of solvent-solute have well fitted with solubility order of uridine in selected solvents.