Tridentate (O,N,O) ligands as potential chelator compounds for iron overload

Iron(III) complexes of three ligands (H2calm, H3anth and H3hyphS) have been studied by means of potentiometric, various spectroscopic (UV–Vis, 1H NMR, IR), mass spectrometric, electrochemical and computational (DFT) methods. For investigation of the selectivity of these ligands the studies were completed by characterization of their iron(II)-, copper(II)-, manganese(II)-, calcium(II)- and aluminum(III)-complexes. All three ligands are able to bind iron(III) in strong acidic pH via (O−,N,O−) donor set. The coordination of two ligands in the bis(ligand)complexes saturates the coordination sphere of iron(III) and the meridonial arrangement was supported by DFT methods. The ligands with (O−,N,O−) donor set are able to bind iron(III) selectively at physiological pH. Moreover, the electrochemical parameters of complexes rule out that iron(III) complexes can initialize the formation of reactive oxygen species. These results clearly show that this type of ligands with (O−,N,O−) donor set is suitable for the designing of new chelator molecules with possible application to iron overload.