In 2002, we discovered a new class of bicyclic, chelating ligand that bound the f-block ions millions of times better than their acyclic analogs. During last few years, we studied the coordination chemistry of these ligands and reported on optimized syntheses of this ligand class. We found that the key to success of these ligands is that essentially no structural change occurs within the ligand during the ion-binding event. Studies of the binding affinities of the ligand with the actinides provide further support for the design. These findings validate the original design of the ligand that was based upon the premise that a ligand that presented the optimized alignment of donor atoms to the ion would lead to enhanced binding.

Recently we began to develop novel gold nanoparticle-based sensors that are hybrid organic/inorganic malonamide/nanoparticle materials. We are using the optical properties (strong absorbance at 525 nm) of gold nanoparticles coupled with the lanthanide-specific binding of the malonamides to produce a colorimetric sensor that is specific for the lanthanides down to about 50 nM and is not affected by potentially interfering transition metal ions.

We are developing synthetic routes for the synthesis of nonsymmetrical bicyclic diamides that we expect we will be able to attach to gold nanoparticles to produce significantly more sensitive sensors.   We’re also working on a novel approach to diluting out the malonamide ligands within the ligand shell in order to reduce the amount of crosslinking in the nanoparticle aggregates and make the sensing mechanism more reversible.

Students and postdoctoral associates working in this project area:

Zack Kennedy
Dr. Tatiana Zaikova

Recent publications associated with this project:

Lumetta, G.J.; Rapko, B.M.; Garza, P.A.; Hay, B.P.; Gilbertson, R.D.; Hutchison, J.E. “Deliberate Design of Ligand Architecture Yields Dramatic Enhancement of Metal Ion Affinity,” J. Am. Chem. Soc. 2002, 124, 5644-5645.

Hay, B. P.; Firman, T. K.; Lumetta, G. J.; Rapko, B. M.; Garza, P. A.; Sinkov, S. I.; Hutchison, J. E.; Parks, B. W.; Gilbertson, R. D.; Weakley, T. J. R. " Toward the computer-aided design of metal ion sequestering agents," J. Compounds and Alloys, 2004, 374, 416-419.

Sinkov, S.I.; Rapko, B.M.; Lumetta, G.J.; Hay, B.P.; Hutchison, J.E.; Parks, B.W. “Bicyclic and Acyclic Diamides: Comparison of Their Aqueous Phase Binding Constants with Nd(III), Am(III), Pu(IV), Np(V), Pu(VI), and U(VI),” Inorg. Chem. 2004, 43, 8404-8413.

Parks, B. W.; Gilbertson, R. D.; Hutchison, J. E.; Rather Healey, E.; Weakley, T. J. R.; Rapko, B. M.; Hay, B. P.; Sinkov, S. I.; Broker, G. A.; Rogers, R. D., “Solution and Structural Investigations of Ligand Preorganization in Trivalent Lanthanide Complexes of Bicyclic Malonamides,” Inorg. Chem. 2006, 45, 1498-1507.

Parks, B. W.; Gilbertson, R. D.; Domaille, D. W.; Hutchison, J. E., Convenient Synthesis of 6,6-Bicyclic Malonamides: A New Class of Conformationally Preorganized Ligands for f-Block Ion Binding. J. Org. Chem. 2006, 71, 9622-9627.

Lisowski, C.E.; Hutchison, J.E. “Malonamide-functionalized gold nanoparticles for selective, colorimetric sensing of trivalent lanthanide ions," Anal. Chem. 2009, 81, 10246-10253.

______________________________________________________________________________________