Bisphosphonate chelating agents -: Coordination ability of 1-phenyl-1-hydroxymethylene bisphosphonate towards Cu2+ ions

Potentiometric and EPR data allow for evaluation of the coordination equilibria in the Cu2+-bisphosphonate system. The bisphosphonic ligand was found very efficient in Cu2+ chelation with formation of monomeric and dimeric species. Two phosphonate groups are basic binding sites for metal ion. The involvement of hydroxyl in metal ion coordination is also likely, especially when one phosphonate is protected by dimethyl ester. As the metal bound phosphonate groups are relatively bulky (six oxygens) and their negative charge above pH 4 is high (four per ligand) the equimolar species is a dominant complex at physiological pH. (C) 2001 Elsevier Science Inc. All rights reserved.