Inorganic and Materials Chemistry
Projects in the Schelter Group involve inert atmosphere/Schlenk line synthesis of inorganic and organometallic complexes. Rigorous characterization of new compounds is achieved through X-ray crystallography, NMR, FTIR, and UV-Visible absorption spectroscopies, electrochemistry and magnetic susceptibility studies. Current projects are focused on the chemistries and electronic structure effects of the lanthanides, uranium and main group elements
Advanced Rare Earths Separations Chemistry
The rare earth elements: La-Lu, Y and Sc are used in critical renewable energy applications including wind turbine generators and hybrid electric vehicle batteries. These modern applications require pure rare earth elements that must be separated from their composite mineral sources. The Peoples Republic of China currently holds ~97% of the international rare earths market comprising nearly all aspects of the (environmentally taxing) supply chain. To develop other sources of rare earths and reduce the environmental impact of their isolation, there is a clear need for new separations chemistry that reduces the cost of industrial-scale rare earths separations. This project seeks to develop a totally new extractant strategy by harnessing the physicochemical distinctiveness of certain high-value rare earths. New designer rare earth extractants will enable selective separations chemistry for these technologically critical elements.
Capturing Heavy-Fermion Type Electron Correlations in Molecular Complexes
The intermetallic heavy-fermion materials, comprising intermediate valence f-elements such as cerium, are characterized by exotic emergent phenomena including unconventional superconductivity. Recent results on these materials suggest a common energy scale for the emergence of the superconducting state, dependent on the local magnetic interaction of f-moments with conduction electrons. Local electron correlations are also believed to underpin the high Tc superconductivity of other families of materials. Parallel studies in molecular chemistry have begun to show inorganic and organometallic complexes are capable of exhibiting the same type of mixed-valency and correlations found in the heavy-fermion materials.
This project will generalize the requirements for emergence of Kondo-like phenomena in magnetically-dilute molecular complexes. New materials will be synthesized from fundamental units of electron correlation to three-dimensional molecular phases.
Exploring the Inverse Trans Influence in the Chemistry of Uranium
Antithetical to the trans influence in transition metal chemistry, which results in a weakening of metal-ligand bonds trans to strongly-bound groups, is the inverse trans influence in the chemistry of the actinides. Semi-core p-orbital mixing with valence d- or f-orbitals gives rise to the influence, however, the presence of both orbital types in the actinide valence shell precludes its simple description. The large thermodynamic stability of the ubiquitous linear, trans-dioxo uranyl cation, UO22+ is one important consequence of this influence.
This project will develop new complexes in varying geometries and coordination environments to systematically study the inverse trans influence in the structural chemistry of uranium. These results will have direct relevance to the bio-remediation of actinide contaminated ground waters, for which the thermodynamic driving force of the influence plays an important role.
- B.S. Michigan Technological University (1999)
- Ph.D. Texas A&M University, Advisor: Kim R. Dunbar (2004)
- Glenn T. Seaborg Postdoctoral Fellow, Los Alamos National Laboratory (2004-2005)
- Director's Postdoctoral Fellow, Los Alamos National Laboratory (2006)
- Frederick Reines Postdoctoral Fellow in Experimental Sciences, Los Alamos National Laboratory (2006-2009)