Dr. Christopher L. Cahill talk on Hybrid materials from the f-block: restricted speciation and supramolecular assembly

About the event

Washington State University
Institute of Nuclear Science and Technology

Presents

Dr. Christopher L. Cahill
Professor of Chemistry and International Affairs – George Washington University

“Hybrid materials from the f-block: restricted speciation and supramolecular assembly”

The synthesis of f-element bearing hybrid materials has seen increased attention of late, owing largely to the tremendous structural diversity and potential applications from spent nuclear fuel stewardship to solid-state lighting. Many materials may be considered as coordination polymers wherein multifunctional organic ‘linkers’ assemble inorganic building units into extended architectures.  Hydrothermal synthesis is a common route to the formation of these materials and metal ion hydrolysis often contributes to structural diversity by producing oligomerized metal centers. Whereas this is a productive route to new materials, the inability to control the extent of hydrolysis, and consequently what species manifest in the solid state, provides a challenge to producing targeted topologies.

We have developed an approach of ‘restricted speciation’ wherein hydrolysis is minimized through the use of complexing ligands in either high-halide media, or via chelating species such as terpyridine molecules. Molecular species are produced in solution with appropriate functionality (halogens, H-bond donors/acceptors) to participate in non-covalent interactions. One then assembles these lower dimensional species through supramolecular synthons (pi-stacking, halogen bonding etc.) to produce extended architectures.  Advantages include a greater degree of predictability of structural motifs, along with the ability to impart systematic substitutions to explore structure property relationships.  Presented will be an overview of our efforts in the Ln(III), [UO₂]²⁺ [NpO₂]²⁺ and [PuO₂]²⁺ systems.