Synthetic development of C(3)-symmetric triphenoxymethane based reagents for the selective recognition and sequestration of lanthanides and actinides

The prospective increase of global nuclear power utilization requires a significant modification of nuclear waste management to help overcome related environmental, economic, and political challenges. The collaborative effort with Argonne National Laboratory has led to the development of reagents with the ability to selectively bind lanthanides and actinides in conditions simulating nuclear waste solutions, and could contribute to the advancement of the nuclear fuel and waste reprocessing strategies. The focus has been placed on the fundamental chemistry of metal-ligand interactions both in the solid state complexes and in solution. The study of these complexes assisted in the design of improved systems for metal separation. A sequence of tripodal chelates bearing a variety of binding moieties, diglycolamide (DGA), thiodiglycolamide (TDGA), carbamoylmethylphosphine oxide (CMPO), carbamoylmethylphosphine sulfide (CMPS) and pyridine N-oxide (PyNO), precisely arranged on a C3-symmetric triphenoxymethane molecular platform were synthesized. The impact of structural modifications of these ligands on their affinity for f-element ions in 1 M nitric acid extraction system has been evaluated.; The preorganization of three diglycolamide binding units on the triphenoxymethane scaffold resulted in significant enhancement of the extraction efficiency and selectivity within trivalent lanthanide ions series. Additionally, the tris-diglycolamide chelate has been recognized as the first single, purely oxygen based donor capable of fully satisfying the tricapped trigonal prismatic geometry favored by nine coordinated lanthanides. The CMPO-based ligand has shown an excellent binding efficiency and a remarkable selectivity for tetravalent actinides. The structural modifications of this chelate system led to the development of one of the most efficient plutonophiles. Experiments with CMPS, TDGA and PyNO compounds provided valuable information about the coordination preferences of the tested cations in the solid state complexes and in solution.; The synthetic development and characterization of tripodal chelates and their metal complexes are presented herein. The impact of the structural derivatization of ligands on lanthanide and actinide ion extraction and separation is also discussed along with its implication towards potential applications in waste reprocessing.