Octadentate Ligands Containing 2,3‐Dihydroxybenzamide and 2,3‐Dihydroxyterephthalamide Coordinating Subunits on a Tetrapodal Amine Backbone for Chelation of Actinides

The linear octadentate ligand 3,4,3‐LICAM(C) ( 2 ) is one of the most effective chelating agents for Pu IV that is not acutely toxic; however, at physiological pH, due to the weak acidity of the catechol hydroxy groups and the large proton dependence of the complexation reaction, only three of the four catecholate subunits are coordinated to Pu IV . To overcome this disadvantage, a new topological class of octadentate ligands based on tetrapodal amine backbones and 2,3‐dihydroxyterephthalamide ( 3 ) (TAM) binding units were designed and synthesized. The amide substituents provide a handle by which the functionality of the ligand can be readily modified, and this synthetic strategy and procedure can be extended to prepare a variety of new multidentate metal‐coordination and extraction agents. A streamlined synthesis for the terephthalamides, both symmetric and asymmetric, was recently reported. In this work, the synthetic details of their incorporation into octadentate systems for use as coordination or extraction agents for Pu IV or other metals in the +4 oxidation state are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)