© 2016-2018 by The Trustees of Georgia Institute of Technology

Georgia Institute of Technology - School of Chemistry and Biochemistry

Molecular Science and Engineering - 901 Atlantic Dr NW, Atlanta, GA 30322

Henry S. La Pierre

la_pierre[at]chemistry.gatech.edu

Office: (404) 385-3258

The La Pierre Research Group develops the molecular and solid-state coordination chemistry of the f-elements for unique and scalable solutions to contemporary problems in energy use. Applications in energy conversion (photochemical, magnetic) and transport (electrical) and in information storage and processing will be sought. Students will receive rigorous training in air-sensitive organometallic synthesis and in solid-state synthetic methods. A broad range of physical methods including single crystal and powder X-ray diffraction, magnetometry, electrochemistry, and multinuclear NMR, UV/Vis, IR, EPR, and X-ray absorption spectroscopies will be used to characterize new complexes and materials.

f-element Magnetic Coupling and the Emergence of Correlated Electron Properties

This research program seeks to establish ‘chemistry-based rules’ that will provide a new basis for innovation in controlling magnetic properties of f-electron materials. New, predictive models, based on the application of modern ligand K-edge XAS to carefully designed synthetic systems spanning ‘simple’ molecular complexes up through clusters and extended solids, will be developed to quantify orbital contributions to magnetic exchange. This new understanding of f-element magnetic exchange will be applied to the synthesis and characterization of materials with bulk properties derived from correlated electron behavior. Of particular interest are solid-state systems with large spin-degeneracies, also known as spin-liquids, which potentially can be exploited for a variety of applications including high–temperature superconductivity and quantum information technologies.

Constructing Tetravalent Lanthanide Chemistry in Solution and Solid-State

Physical properties and chemical reactivity that are dependent upon covalent bonding play a limited role in contemporary lanthanide chemistry because of the lack of covalent bonding of the 4f (and 5d) orbitals in the lanthanide trivalent state. However, the oxidation chemistry of the lanthanides is potentially quite rich. Leading reports have demonstrated that Pr(IV) and Tb(IV) are accessible as molecular complexes even in aqueous solution, and that the early lanthanides through Sm and the late lanthanides through Tm should be accessible in the solid-state in their tetravalent oxidation state. This research effort will employ the increased covalency and crystal field splitting of the tetravalent lanthanide ions for the development of significantly improved hard magnets and the synthesis of molecular oxides for oxidation based separations, atom transfer reagents, and catalysts.

f-element Photochemical Small Molecule Functionalization Catalysts and Photosensitizers

Preliminary reports indicate that the f-elements have technologically relevant photochemistry. Since the lanthanides have similar terrestrial availability to the late first-row transition metals, lanthanide photocatalysts are potentially scalable for global use. Cerium, in particular, offers a unique opportunity to establish a closed photochemical cycle employing water as the terminal reductant for the photoreduction of carbon dioxide. By improving quantum yield and excited state lifetime, the actinides can also offer the opportunity to develop powerful photosensitizers with excitation wavelengths accessible in the visible spectrum. This research program seeks lanthanide and actinide photocatalysts for small molecule functionalization and photosensitizers for a variety of organic transformations by developing coordination chemistry to enable photoexcited states derived from MMCT and MLCT excitations.

Efficient f-element Separations Driven by Steric Congestion and Allosteric Electrocrystallization

Separations of the f-elements, both between the lanthanides and between lanthanides and the later actinides, are among the most difficult metal-ion separations due to the similarity of the chemical properties of the elements under ambient conditions. Improvements in the commercial processes for these separations are necessary to meet the increasing demand for high purity lanthanides for use in advanced technologies such as permanent magnets and fluorescent lighting and to remove the minor actinides from spent nuclear fuel in support of time efficient disposal of high-level radioactive waste. This research program seeks novel separation methodologies based on steric congestion and allosteric electrocrystallization.