Investigation of the electrochemical behavior of curcumin in a mixed solution of water and ethanol by means of cyclic voltammetry and quantum chemical calculations

In the present work, a computational analysis of the chemical structure of curcumin, the most important component of turmeric, is carried out by means of state-of-the-art methods of calculations. High-level ab initio calculations (G4) along with reliable methods of density functional theory (DFT) have been used to studythe enol-diketo tautomerism of curcumin. The electrochemical behavior of curcumin has been also investigated by means of cyclic voltammetry and standard theoretical quantum chemical calculations in a mixed solvent of water-ethanol. The pH dependence of the redox activity of curcumin derivatives in the mixture solutions at different temperatures has been used for the experimental determination of the standard reduction potential and changes of entropy, enthalpy, and Gibbs free energy for the studied reaction. The electrooxidation process leads to several products that are studied theoretically using DFT calculations. The calculated values of E° are in good agreement with the experiment. Uniquely, the change of solvation energy for the studied reaction has been investigated by two models and the results are in perfect agreement with one another.