Complexation of Ca2+ and Mg2+ with aminopropylidenebisphosphonic acids in aqueous and micellar solutions of cetylpyridinium chloride

The dissociation constants and stability constants of calcium and magnesium complexes with 3-amino-1-hydroxypropylidenebisphosphonic, 3-dimethylamino-1-hydroxypropylidenebisphosphonic and 3-morpholino-1-hydroxypropylidenebisphosphonic acids have been obtained in this work in aqueous solutions (I = 0.1 M, KCl) and 0.1 M micellar solutions of cetylpyridinium chloride (CPC) by pH-potentiometric titrations. The increase of aminopropylidenebisphosphonic acid strength was observed in micellar CPC solutions. The micellar media of CPC affects in a different way on the stability of calcium and magnesium ions complexes with anions of aminopropylidenebisphosphonic acids. The pronounced effect of micellar CPC media on dissociation of 3-morpholino-1-hydroxypropylidenebisphosphonic acid and its complexation with calcium and magnesium ions was observed.