Chelating Properties of γ‐Aminobutyrohydroxamate Resin toward Lanthanides

Abstract

γ‐Aminobutyrohydroxamate resin that simulate siderophore analogues was prepared. The structure and conversion of functional groups of the resin were confirmed with IR spectra and elemental analysis. The influence of pH on adsorption of metal ions to the resin was examined. Uptake of metal ions increased with pH and was quantitative in the pH range of 4 to 6 for most of the lanthanides. These metal ions showed high exchange rates towards the resin. The complexation behavior of the resin was also investigated by means of IR and potentiometry. The dissociation constant, pKa of the hydroxamic hydroxyl group is 9.36. Stability constants of the insoluble lanthanide complexes on the resins were measured potentiometrically at 25 ± 0.1 °C and ionic strength of 0.1 M KCl. The results were compared with those of the corresponding soluble lanthanide complexes. It was found that a higher stability of the resin resulted in an increase of the stability constants. The phenomena might be due to the length of the spacer in providing the proper geometry of the resin ligand for intramolecular metal complexation.