Bifunctional 3-Hydroxy-4-Pyridinones as Potential Selective Iron(III) Chelators: Solution Studies and Comparison with Other Metals of Biological and Environmental Relevance.

The binding ability of five bifunctional 3-hydroxy-4-pyridinones towards Cu and Fe was studied by means of potentiometric and UV-Vis spectrophotometric measurements carried out at = 0.15 mol L in NaCl = 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 Cu and Fe behaviour in aqueous solution. Furthermore, the sequestering ability and metal chelating affinity of the ligands were investigated by the determination of p and pM parameters at different pH conditions. Finally, a comparison between the Cu and Fe/3-hydroxy-4-pyridinones data herein presented with those already reported in the literature on the interaction of Zn and Al with the same ligands showed that, from the thermodynamic point of view, the 3-hydroxy-4-pyridinones are particularly selective towards Fe 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 Cu and Zn.