Thermodynamic modeling studies of aqueous solubility of caffeine, gallic acid and their cocrystal in the temperature range of 303Â K-363Â K

Caffeine and gallic acid are two of the major components of tea extract observed to form cocrystal when mixed together in aqueous solutions. Characterization of this cocrystal by different techniques shows a strong hydrogen bonded structure. Formation of this cocrystal causes a decrease in solubility of caffeine and gallic acid and hence precipitation of these components from the solutions. The Non-random Two-Liquid (NRTL) model was used to correlate the solubility data obtained experimentally in terms of activity coefficient and thereby predicting the solubility of caffeine, gallic acid and their cocrystal at other temperatures. Molecular dynamic simulations (MD) were performed for an insight into the intermolecular interactions between caffeine and gallic acid in water that lead to aggregate formation when the two are present together in aqueous solutions.