A spectrophotometric and DFT study of the behavior of 6-bromoquercetin in aqueous solution

Acid–base activity, keto-enol tautomerism and complexing properties of 6-bromoquercetin are investigated in water media under different conditions. The constants of dissociation (pKa) have been determined in pH region at various ionic strengths. The analysis of the protonation process is conducted in strongly acidic solutions of HCl. The complexation was studied with trivalent lanthanides. The formation constants of monocomplex species ML (M(III)=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, Lu) have been obtained. DFT calculations were carried out for interpretation and verification of received results.