The Bisphosphonate Odyssey. A Journey from Chemistry to the Clinic

Methylidynetrisphosphonates: Promising C1 building block for the design of phosphate mimetics

Methylidynetrisphosphonates are representatives of geminal polyphosphonates bearing three phosphonate (PO3H2) groups at the bridged carbon atom. Like well-known methylenebisphosphonates (BPs), they are characterized by a P-C-P backbone structure and are chemically stable mimetics of the endogenous metabolites, i.e., inorganic pyrophosphates (PPi). Because of its analogy to PPi and an ability to chelate metal ions, the 1,1,1-trisphosphonate structure is of great potential as a C1 building block for the design of phosphate mimetics. The purpose of this review is to present a concise summary of the state of the art in trisphosphonate chemistry with particular emphasis on the synthesis, structure, reactions, and potential medicinal applications of these compounds.

Bisphosphonate chelating agents. Coordination ability of 1-phenyl-1-hydroxymethylene bisphosphonate towards Cu(2+) ions

Potentiometric and EPR data allow for evaluation of the coordination equilibria in the Cu(2+)-bisphosphonate system. The bisphosphonic ligand was found very efficient in Cu(2+) 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.