Curcumin in silver nanoparticles aqueous solution: Kinetics of keto-enol tautomerism and effects on AgNPs

The tautomerism of curcumin (CUR) in aqueous solution was investigated in the presence of silver nanoparticles (AgNPs) in the temperature range 294−314 K. The kinetic data indicate that the conversion of the keto-enol into the diketo form is associated to higher rate constants in comparison to those obtained in pure water. Moreover, nonlinear Arrhenius behavior was observed in the investigated temperature range. The effects of CUR on the AgNPs were determined by zeta potential and dynamic light scattering measurements and supported by spectroscopic analysis suggesting that interactions with metal surface occur preserving nanoparticles from self-aggregation in the investigated conditions. The results reported herein contribute to enhance the kinetics of CUR tautomerism in aqueous media.