INVESTIGATION AND OPTIMIZATION OF COMPLEXATION OF MANGANESE (II) IONS WITH DIHY-DROQUERCETIN IN AQUEOUS SOLUTIONS

Abstract

The purpose of this work was to study and optimize the complexation reaction of Mn2+ ions with flavonoid dihydroquercetin (DHQ) in aqueous solutions. It was found that the interaction of DHQ (0.015–0.030 M) with manganese (II) salts at molar ratios of DHQ : Mn2+ from 1 : 1 to 1 : 3 at pH 6.9–7.9 leads to the formation of a complex compound (CC) with a stoichiometric ratio of metal : flavonoid ligand (Met : L) 1 : 1. The conditions for the complexation of Mn2+ ions with dihydroquercetin at laboratory conditions optimized for the yield of the product, are proposed. The maximum yield of the complex (95%) was achieved at the interaction of DHQ with Mn(CH3COO)2∙4H2O under conditions: pH 7.7, 70 °C, the reaction time was 15 min, the molar ratio of the initial reagents DHQ: Mn2+ was 1 : 1.5, the initial concentrations were 0.020 M DHQ and 0.030 M Mn2+. The most probable composition of the complex with the determination of the amount of bound water [MnL(OH)(H2O)2] and the structure of the complex were established using the data of thermogravimetry (TG), differential scanning calorimetry (DSC), elemental analysis and X-ray fluorescence analysis (XRF), confirmed by the data of total reflection X-ray fluorescence analysis (TXRF), and EPR spectroscopy data.