Spectroscopic and Potentiometric Study of 2,3-Dihydroxybenzoic Acid and its Complexation with La(III) Ion

The equilibrium reactions between 2,3-dihydroxybenzoic acid (2,3-DHBA) and Lanthanum(III) ion was investigated in an aqueous medium of 0.1M ionic strength and 25±1 °C by potentiometric and spectrophotometric methods. Formation of complexes of the types ML andML2H were observed and their stability constants were reported. The ligand showed competitive coordination mode in solution: in acidic medium, 2,3-DHBA showed preference to salicyclate type whereas catecholate type in basic media.