Complexation of 3,4-hydroxypyridinecarboxylic acids with Iron(III)

The chemical interactions of 3-hydroxy-4-pyridinecarboxylic acid (3H4P) and 4-hydroxy-3-pyridinecarboxylic acid (4H3P) with Fe(III) were investigated in aqueous 0.6 m (Na)Cl at 25 °C by means of potentiometric titrations and UV–Vis spectrophotometry. A large number of mononuclear complexes were formed in solution; one of the Fe/3H4P species was obtained as a solid and characterised by elemental analysis. In view of a possible application to iron(III) chelation therapy, the efficiencies of the ligands to chelate iron(III) were evaluated in vitro at physiological pH. Chelation efficiency with iron was low and less than previously observed with aluminium(III).