Research in the Knope group broadly focuses on chemistries that address challenges in the areas of energy, sustainability, and environmental management. Under this umbrella we have developed two research thrusts that include (1) examining structure property relationships in luminescent bismuth based materials to address “critical element” research needs and (2) understanding the chemical behavior of actinides under conditions relevant to nuclear waste management, environmental transport, and separations processes.
Examining structure property relationships in bismuth based materials
One thrust of our research program has focused on the development of photoluminescent compounds that address our energy, lighting, and security needs, while also reducing our dependence on rare earth resources or “critical elements,” for which there exists national security concerns over their long-term availability; in 2015, phosphors and luminescent materials represented one third of the total value of the lanthanides used worldwide. Though only a handful of photoluminescent bismuth-organic materials have been reported, coupled with the low cost, low toxicity, and robust photo- and thermal stability of bismuth and its compounds, bismuth-based materials bearing luminescent ligands or into which intrinsically luminescent metal centers may be incorporated are attractive candidates for PL materials development. Towards this end, we have been examining bismuth coordination and materials chemistry with the aim of developing rational synthesis and design strategies for bismuth organic materials, examining structure-luminescent behavior relationships, and gaining a fundamental understanding of the optical behavior of bismuth organic materials.
Batrice RJ, Ridenour JA, Ayscue RL, Bertke JA, Knope KE*. Synthesis, Structure, and Photoluminescent Behavior of Molecular Lanthanide-2-Thiophenecarboxylate -2,2’:6’,2’’-Terpyridine Materials. CrystEngComm 2017: DOI: 10.1039/C7CE01192J
Batrice RJ, Adcock AK, Cantos PM, Bertke JA, Knope KE*. Synthesis and Characterization of an Isomorphous Lanthanide-Thiophenemonocarboxylate Series (Ln = La-Lu, except Pm) Amenable to Color Tuning. Crystal Growth & Design 2017 DOI 10.1021/acs.cgd.7b00400.
Adcock AK, Batrice RJ, Bertke JA, Knope KE*. Structural diversity in bismuth(III)-thiophenemonocarboxylates. European Journal of Inorganic Chemistry, 2017: 1435-1445. DOI: 10.1002/ejic.201601368
Since joining the faculty at Georgetown University, Prof. Knope has established a research lab that is well suited (and equipped) for handling radioactive material including Th and U and developed a synthetic program that focuses on the formation, composition, and stability of actinide complexes and clusters isolated from aqueous solution. This work is motivated by recent studies that have shown that the identity of actinide-ligand complexes (their composition, charge, and nuclearity) plays an important role in understanding the overall chemical behavior of the actinides. Though it is well established that the nature of the metal ion, the complexes it forms, their stability in solution, and the conditions over which it precipitates is an important first step in developing a predictive understanding of the chemical behavior of a metal ion, our understanding of actinide speciation remains limited and continues to thwart efforts to reliably and predictably control the behavior of these elements. Our synthetic program thus aims to shed new light on the formation, stability, and precipitation of An(IV) complexes and clusters that may be applied to developing strategies for the remediation of contaminated sites, long-term storage of spent nuclear fuel, and environmental management. Current work focuses on the effects of both inner- and outer- coordination sphere interactions on speciation. Beyond establishing structural systematics in these systems, we are also examining the correlation between solution species and those complexes observed in the solid-state.
Wacker JN, Vasiliu M, Huang K, Baumbach RE, Bertke JA, Dixon DA, Knope KE*. Uranium(IV) Chloride Complexes: UCl62- and an Unprecedented U(H2O)4Cl4 Structural Unit. Inorganic Chemistry, 2017, DOI: 10.1021/acs.inorgchem.7b01293.
Batrice RJ, Wacker JN, Knope KE. Actinide Complexes, Clusters, and Nanostructures Isolated from Aqueous Solution in Experimental and Theoretical Approaches to Actinide Science, Wiley Publishing. Submitted.