Impact of aluminium ions on adriamycin-type ligands

Abstract

Potentiometric and spectroscopic measurements have shown that Al3+ ions form 1:1 complexes with adriamycin and its analogues. The major complex at pH > 5 is a tetrahedral species in which the metal ion is co-ordinated to the ligand via two anthracycline oxygens. Two OH– groups complete the co-ordination sphere. Although the complexes are comparatively stable the formation of [Al(OH)4]– at pH > 8.5 excludes adriamycin from the metal ion co-ordination sites. The unusual fluorometric behaviour of the drug molecule is also present in the complex formed at lower pH.