Synthesis and characterization of a novel soluble hesperetin monoglucoside-copper(Ⅱ) complex using ion exchange column

The coordination of flavonoids with metal ions often improve the biological activity of flavonoids. In this study, an integrated method using ion exchange column for the synthesis of the hesperetin monoglucoside-copper(Ⅱ) complex (the HMG-Cu(Ⅱ) complex) was investigated. The integration including the separation and the coordination reaction of HMG was studied firstly. The stoichiometric ratio of the complex was studied by the method of equimolar solutions and the molar ratios. The compound structures were characterized by theoretical quantum chemical calculation, elemental analysis, ultraviolet–visible (UV–Vis) spectra analysis, Fourier transform infrared (FT-IR) spectra analysis, X-ray diffraction (XRD) patterns analysis, scanning electron microscope (SEM) and thermal methods (TG/DSC) analysis. Results showed that both the carboxyl group and its ortho hydroxyl group in hesperetin monoglucoside (HMG) participated in the coordination reaction. The D296 strong basic anion exchange resins could effectively adsorb HMG. The static adsorption equilibrium time was 20 h and equilibrium data fitted better to the Langmuir model than Freundlich model. The adsorption process was a monolayer adsorption process on homogenous surface of D296 resins and the fitting of the pseudo-second-order model was better. The metal-to-ligand ratio was 1:2. In addition, the complex was greatly affected by pH, the stablest at pH 8.0. So, this research offered a feasible pathway of getting a high value-added complex of HMG-Cu(Ⅱ).