The synthesis and evaluation of bifunctional chelating agents designed to sequester gallium (III) isotopes define the general scope of the project. Taking advantage of the extensive base of chemical literature describing the coordination chemistry of Ga(III), we have established two chelating agents as synthetic targets. The first, a ligand incorporating three catechol binding subunits, forms a trianionic complex with trivalent ions and is expected to display considerable stability at physiological Ph. The second ligand is the macrocyclic polyaminocarboxylate NOTA, which is known to form an exceptionally stable neutral complex with Ga(III). A comparison of the relative efficacy of the two very different ligands should assist the evolution of optimal chelating agents for gallium. The C- 14 labeled bifunctional tris-catechol ligand was synthesized and labeled to Mab B72.3. It has been determined that the synthesis of bifunctional NOTA cannot be performed using the techniques developed for the larger macrocycles DOTA and TETA. Therefore, an alternative synthesis of this interesting chelating agent is underway.
