New chelation strategies for the uranyl ion

Traditional approaches to the design of metal-ion-specific complexing agents have relied to a great extent on the creation of a ligand cavity of the appropriate size and coordination number to accommodate the targeted metal ion. Oxo-metal ions, such as uranyl, cannot be dealt with as spherically symmetric charged atoms and thus present both a special challenge and offer a unique advantage for specific chelation in solution. To maximize recognition of the anisotropic UO22+ ion, new tripodal hexadentate ligands have been prepared providing three carboxyl moieties each to act as a bidentate donor group. The novel ligand design concept, ligand syntheses, and thermodynamic results related to the uranyl complex characterization are presented