Conformationally Preorganized Diamide Ligands for Enhanced Binding of f-Block Elements: New Ligands, Coordination Complexes and Functional Materials

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This proposal builds off Professor Hutchison's recent discovery of a new class of chelating bicyclic diamide ligands that exhibit dramatic enhancements in binding affinity for the f-block elements compared to the large class of ligands based upon the malonamide substructure. The new ligand class, the 3,9-diaza-3,9- dialkylbicyclo[ 4.4.0]decane-2, 10-diones, were identified using a rational approach utilizing molecular mechanics modeling. The preorganized bicyclic structure ideally positions the two carbonyl groups for optimal metal-ligand interaction. A highly efficient and versatile synthesis of this ligand class has been developed and ion extraction experiments have shown a 3 to 5 million-fold enhancement in affmity for f- block ions when compared to several analogous acyclic diamides. This initial discovery suggests a rich class of ligands can be prepared wherein the binding affinity for f- block elements can be widely tuned. The overall goal of this proposal is to identify methods by which the new ligands can be rationally designed and rapidly optimized through an integrated theory, synthesis and testing program. The three primary objectives in this proposal are designed to help elucidate the design criteria that dictate the properties of this new class of ligands. These objectives are (i) developing synthetic methods that permit wide variation of the ligand structure (ranging from the nature and position of alkyl and aryl substituents to the ring sizes within the bicyclic structure), (ii) investigating the solution and solid-state coordination chemistry of the new ligands and relating this chemistry back to the ligand design and (iii) incorporating these ligands into functional materials (polymers, organic thin films). With this Award, the Organic and Macromolecular Chemistry Program supports the research of Professor James Hutchison of the University of Oregon whose work involves ligand design, synthetic chemistry, spectroscopy methods, coordination chemistry, crystallography, solvent extraction, and materials chemistry. This work will enhance student training through exposure to a wide range of research. It will also contribute to society by targeting such applications as nuclear fuel reprocessing and high-level waste management, and sensitizers for lanthanide luminesence in fluorescent probes and sensors.