Syntheses and crystal structures of gadolinium and europium complexes of AAZTA analogues

Abstract Modified 6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid (AAZTA) ligands with a hydroxyl arm have been synthesized and characterized. The crystal structures of its lanthanide complexes, determined by single crystal X-ray crystallography, show centrosymmetric nonacoordinated dimeric M 2 L 2 forms where one carboxylate group from each ligand forms a bridge between two metal centers. Each metal center is coordinated with one inner sphere water molecule. The hydroxyl arm does not interfere in the coordination environment of the metal and therefore acts as a good anchor for attaching other functional motifs.