Synthesis, Complexation Properties, and Evaluation of New Aminodiphosphonic Acids as Vector Molecules for Ga Radiopharmaceuticals.

Two new aminodiphosphonic acids derived from salicylic acid and its phosphonic analogue were prepared through a simple and efficient synthesis. 2-[(2-Amino-2,2-diphosphono)ethyloxy]-benzoic acid and 2-[(2-amino-2,2-diphosphono)ethyloxy]-5-ethyl-phenylphosphonic acid were evaluated for their applicability as Ga binding bone-seeking agents. Protonation constants of and and stability constants of the Ga complexes with and in water were determined.