Researchers:
Bevin Parks
Dylan Domaille

Funding By:

Keywords: rational design, bicyclic malonamide, chelate, lanthanide, actinide, binding affinity, extraction, sensors, functional materials.

Goal #1: Rational design of new ligands for binding and extraction of lanthanides and actinides.

In collaboration with Dr. Benjamin Hay and his co-workers at Pacific Northwest National Labs (PNNL), we recently set out to determine the architectural design criteria for f-block ion sequestering agents based upon malonamide chelates. MM3 calculations allowed us to identify a diamide architecture that is preorganized for complexation and offers binding sites that are complementary for the trivalent actinides and lanthanides. The models predict that almost no reorganization of the ligand will be necessary upon metal binding. We subsequently synthesized the bicyclic diamide and showed in extraction studies that the new ligand possesses a distribution coefficient that is ten million times greater than its acyclic analog, confirming the model and providing indirect evidence for the structural preorganization of the ligand. In collaboration with Dr. Brian Rapko's group at PNNL, we investigated the aqueous coordination chemistry of the new ligand class. Preliminary data suggest that our malonamide molecule has four to seven orders of magnitude increased binding affinity compared to acyclic analogs such as N,N,N',N'-tetramethylmalonamide.

Goal #2: Target functional materials by altering the synthesis to change either the amide functionalities or the ring structures of the bicyclic malonamides.

Although we are still investigating the ligand synthesis and coordination chemistry of this new ligand class, we are already exploring the use of these ligands in functional materials. Incorporation of the binding moiety into polymers, thin films, membranes, and nanoparticles appears to be an excellent approach to designing materials for use in applications such as sensing and separating members of the f-block elements. The research carried out to date also provides the foundation for use of these ligands in novel materials such as lanthanide photosensitizers and molecular switches.

Recent publications associated with this project:

Lumetta, G. J.; McNamara, B. K.; Rapko, B. M.; Hutchison, J. E. Inorg. Chim. Acta 1999, 293, 195-205.

Lumetta, G. J.; McNamara, B. K.; Rapko, B. M.; Sell, R. L.; Rogers, R. D.; Broker, G.; Hutchison, J. E. Inorg. Chim. Acta 2000, 309, 103-108.

Lumetta, G. J.; Rapko, B. M.; Garza, P. A.; Hay, B. P.; Gilbertson, R. D.; Weakley, T. J. R.; Hutchison, J. E. J. Am. Chem. Soc. 2002, 124, 5644-5645.

Lumetta, G. J.; Rapko, B. M.; Hay, B. P.; Garza, P. A.; Hutchison, J. E.; Gilbertson, R. D. Solvent Extr. Ion Exch. 2003, 21, 29-39.

Sinkov, S. I.; Rapko, B. M.; Lumetta, G. J.; Hutchison, J. E.; Parks, B. W. Plutonium Futures AIP Conference Proceedings 2003, 673, 36-38.