Find in Library

The binding ability of five bifunctional 3-hydroxy-4-pyridinones towards Cu²⁺ and Fe³⁺ was studied by means of potentiometric and UV–Vis spectrophotometric measurements carried out at <i>I</i> = 0.15 mol L⁻¹ in NaCl_(aq),<i>T</i> = 298.15 K and 310.15 K. The data treatments allowed us to determine speciation schemes featured by metal-ligand species with different stoichiometry and stability, owing to the various functional groups present in the 3-hydroxy-4-pyridinones structures, which could potentially participate in the metal complexation, and in the Cu²⁺ and Fe³⁺ behaviour in aqueous solution. Furthermore, the sequestering ability and metal chelating affinity of the ligands were investigated by the determination of p<i>L</i>_0.5 and pM parameters at different pH conditions. Finally, a comparison between the Cu²⁺ and Fe³⁺/3-hydroxy-4-pyridinones data herein presented with those already reported in the literature on the interaction of Zn²⁺ and Al³⁺ with the same ligands showed that, from the thermodynamic point of view, the 3-hydroxy-4-pyridinones are particularly selective towards Fe³⁺ and could therefore be considered promising iron-chelating agents, also avoiding the possibility of competition, and eventually the depletion, of essential metal cations of biological and environmental relevance, such as Cu²⁺ and Zn²⁺.