CAREER: Bifunctional and Bimetallic Single-Site Catalysts for Sustainable Synthesis

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With funding from both the Chemical Catalysis program in the Division of Chemistry (CHE) and the Solid State and Materials Chemistry program in the Division of Materials Research (DMR), Dr. Dianne Xiao and her research group at the University of Washington will design new heterogeneous catalysts that will enable more sustainable chemical synthesis, including the use of renewable feedstocks and the replacement of hazardous reagents. Her group will explore how multiple metal centers and organic functional groups can work together to catalyze transformations not achievable by a single component in isolation. Dr. Xiao will also be engaged in multiple outreach and educational activities aimed at broadening STEM participation and enhancing public scientific literacy. These will include developing outreach activities in partnership with local museums and organizations, designing new inquiry-based labs and educational resources at the college level, and creating a series of science lectures aimed at informing the public on energy and environmental issues.In enzymes, multiple organic and inorganic functional groups work together to lower activation barriers and enhance reaction rates. Applying these bioinspired concepts to the design of new heterogeneous catalysts, this project will explore a simple yet versatile templating strategy for precisely positioning multiple functional groups within metal–organic framework pores. Current approaches for tethering bimetallic and bifunctional sites to solid surfaces suffer from active site non-uniformity, low structural precision, and poor chemical tunability. These synthetic limitations have, in turn, greatly limited our knowledge of how these structural motifs behave and react in a heterogeneous catalysis context. Our proposed templating strategy provides an opportunity to explore the chemistry of bimetallic and bifunctional active sites and identify nuanced catalyst structure–activity relationships. For example, how do acid-base distance, pKa, and structural flexibility influence the activity and stability of bifunctional aldol condensation catalysts? Similarly, what roles do metal identity, nuclearity, and ligand environment play in facilitating bimetallic O2 activation and transfer? Answers to these questions will help inform the development of future condensation and oxidation catalysts that enable waste valorization and promote green chemistry principles. Using these new synthetic tools, Dr. Xiao will interrogate sophisticated surface-supported active sites, including bifunctional acid–base sites for biomass utilization and bimetallic species for aerobic oxidation catalysis. Dr. Xiao will also be actively engaged in STEM outreach programs across multiple age demographics, from K–12 to college and the older adult population.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.