RUI: Molecular Alkali Metal Catalysts for Selective Reduction of Oxygen-Containing Functionalities

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With the support of the Chemical Catalysis Program in the Division of Chemistry, Guoqi Zhang of the John Jay College of Criminal Justice at the City University of New York is studying alkali metals (lithium, sodium, and potassium) in combination with specially designed ligands to promote processes of potential utility for the manufacture of fuels and other commodity chemicals of benefit to society from renewable biomass-derived feedstocks. Alkali metals are among the most abundant metallic elements in the Earth’s crust but their ability to catalyze chemical reactions is underexplored as compared to rare and expensive precious metal-based catalysts, which are commonly used in the contemporary chemical industry. The supported research focuses on the development of simple methods to create well defined alkali metal-ligand complexes from readily available starting materials and investigation of their effectiveness as catalysts for a range of relevant chemical processes. The experiments necessary to pursue the aims of the project are rigorous but designed to be straightforward enough to be conducted by entry-level undergraduate students, or even high school students, and the research will provide a diverse group of young scientists with the opportunity to gain hands-on laboratory experience. John Jay College is classified as a major Hispanic-Serving Institution and its Science Department serves a large number of students belonging to groups traditionally underrepresented in STEM (science, technology, engineering and mathematics) fields. As such, it is anticipated that the funded activities will not only provide education and training at the interface of chemical catalysis, organic chemistry, and inorganic chemistry, but also serve as a vehicle to help diversify the pool of future science professionals. The broader impacts of the award are further extended by the participation of Dr. Zhang in nationally recognized mentoring programs such as the Program for Research Initiatives for Science Majors (PRISM).There is currently great interest in exploring the replacement of precious metal-based catalysts used in many of today's important chemical processes with catalysts instead derived from earth abundant metals. Such a change would likely reduce the costs of chemical manufacturing while also improving its environmental sustainability. Alkali metal complexes have emerged in recent years as platforms for catalysis and their successful application in reduction chemistry could improve the sustainability of biomass processing. Accordingly, the funded project is focused on the study and development of well defined complexes of Li, Na, and K cations ligated with 2,2':6',2''-terpyridines (or crown ethers) for the reduction of a wide range of oxygen-containing functionalities, including carboxyl derivatives (e.g., carboxylic acids, esters, amides) and ethers, using silanes or molecular hydrogen as stoichiometric reductants. Functional group compatibility within more complex substrates will be explored alongside other important parameters such as the regio-, stereo-, and chemo-selectivity of the various catalytic reductive transformations. These investigations will be concentrated on discovery of the most active and selective catalyst candidates and on scrutiny of a putative dual-activation reactivity mode based on a frustrated Lewis pair, through which the complexes are proposed to exert their catalytic effects. Mechanistic studies will be conducted via a combination of experimental and theoretical, density functional theory (DFT)-based methods in order to understand both the observed structure-activity relationships and the importance of metal-ligand cooperativity.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.