Exploring the solubility and solvation thermodynamics of coumarin in a range of aqua-organic solvents

Abstract

In this study, we investigated the solubility of coumarin in aqueous solution and binary mixtures of N,N-dimethylformamide (DMF), acetonitrile (ACN), and dimethylsulfoxide (DMSO) through experimental measurements. The solubility experiments were carried out using the analytical technique of UV-Vis spectroscopy in a temperature range of 288.15–308.15 K under atmospheric pressure using a digital temperature controlling thermostat. Water–DMF mixture system exhibited the highest solubility of coumarin, whereas water–ACN system showed the lowest solubility among the studied solvent systems. To gain a deeper understanding of the solvation process, we employed theoretical studies to optimize the molecular structure of the compound. This optimization enabled the calculation of significant molecular properties, such as close molecular dimension and dipole moment, which play key roles in determining various thermodynamic parameters associated with solvation. By utilizing the measured solubilities, we analyzed the thermodynamic properties of coumarin dissolution, including the Gibbs free energies of the solutions, transfer Gibbs free energies related to cavity formation and dipole–dipole interactions, transfer enthalpy of dissolution, and chemical transfer energetics. These analyses aimed to provide insights into the thermodynamic stability of coumarin-like compounds in solution.