Development of Catalysts and Ligands for Alkyne Metathesis

Louisiana State University, Baton Rouge LA

Investigators

Abstract

With this award, the Chemical Catalysis Program of the Division of Chemistry and the Established Program to Stimulate Competitive Research (EPSCoR) are supporting the research of Dr. Semin Lee of Louisiana State University. Professor Lee and his coworkers are developing new catalysts for alkyne metathesis. Alkyne metathesis is a chemical reaction that exchanges the two halves of carbon-carbon triple bonds. Instead of stitching together small fragments of molecules one-by-one, alkyne metathesis allows chemists to make large, uniform molecules from small building blocks in a single step; however, current state-of-the-art catalysts still have limitations that prevent alkyne metathesis from being widely used. Dr. Lee and his team are synthesizing new catalysts, systematically studying the chemical properties that control metathesis reactions, and creating highly active and user-friendly catalytic systems. The Lee group is also testing strategies to use alkyne metathesis catalysts to form nanohoop molecules. These explorations are helping to accelerate discoveries of new organic materials for electronics and energy storage. Simultaneously, Professor Lee is developing new virtual reality (VR) tools for chemistry education and outreach. VR allows students to grab and manipulate molecules. Professor Lee is implementing VR in his undergraduate and graduate courses where students can interact with molecules and understand their three-dimensional nature along with their corresponding function. VR is also actively being used in K-12 outreach events to bring enthusiasm to young students by letting them walk inside and explore molecules. The development of alkyne metathesis catalysts with improved functional group tolerance, decreased air and water sensitivity, and improved substrate generality is critical for the advancement of alkyne metathesis as a synthetic tool. Dr. Lee and his research group are working towards this goal by systematically studying ligand effects on molybdenum (Mo) and tungsten (W) alkylidyne complexes and investigating the reactivity of cationic alkylidyne complexes. The knowledge generated from these systematic studies is being used to synthesize alkyne metathesis catalysts with enhanced activity and stability. The effect of ligands, metals, and substrates on the formation of proposed catalytic intermediates is being investigated to improve understanding of the reaction process and to support rational design of improved systems. New catalysts are being tested against challenging substrates that have proven to be inactive with current state-of-the-art catalysts. Carefully designed systems for the synthesis of alkyne nanohoops materials are also being studied. Catalysts that show low activity with common alkyne metathesis substrates are being tested as candidates for ring-opening alkyne metathesis polymerization (ROAMP) to suppress undesired chain transfer side reactions. These activities are advancing alkyne metathesis catalysis toward broad synthetic utility and providing a strong training ground for graduate and undergraduate students in catalytic organometallic chemistry. 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.