Potentiometric and Spectroscopic Studies on Yttrium(III) Complexes of Dihydroxybenzoic Acids

The equilibrium reactions of yttrium(III) ion with dihydroxybenzoic acids (2,3-dihydroxybenzoic acid (2,3-DHBA) and 3,4-dihydroxybenzoic acid (3,4-DHBA)) (H3L) were investigated in aqueous solution by means of potentiometric and spectroscopic methods, in 0.1 mol·l−1 ionic strength medium at 25 °C. The stability constants are reported for YL, YL(HL)2− and YL23−- type mononuclear complexes. 2,3-DHBA can bind Y(III) ion strongly and the salicylate mode is effective over the acidic pH range. But in higher pH range, 2,3-DHBA and 3,4-DHBA act more efficiently through catecholate groups. The complexes of 2,3-DHBA are more stable than the complexes of 3,4-DHBA.