Composition, Properties, and Structure of Copper(II) Complexes with 2,4-Dihydroxybenzoic Acid

Abstract

pH titration, optical spectroscopy, and simulations were used to determine the concentration acidic dissociation constants for 2,4-dihydroxybenzoic acid (H3L) and the compositions, stabilities, and species distribution of copper(II) complexes with H3L. At acidic and neutral pHs, 1 : 1 complexes are dominant. At alkaline pHs, differently protonated 1 : 1, 1 : 2, or 1 : 3 complexes form (including hydroxo complexes [CuLOH]2-, [CuL(OH)2]3-, and [CuL2(OH)2]6-), the formation of the particular species being dependent on the metal-to-ligand ratio.