RUI: Small molecule and polymer-supported transition metal catalysts: Investigating reproducibility and metal microenvironment effects

In this project, Professor Madalyn R. Radlauer of the Department of Chemistry at San José State University (SJSU) is working with a primarily undergraduate research group to synthesize and test new molecular facilitators, or catalysts, for useful chemical reactions, and to develop standardized test reactions and reaction conditions so that their performance can be effectively compared with previously reported and future systems. Catalysis is an inherently efficient process, lowering the energy required for a chemical reaction while improving reactivity and selectivity, and reducing waste. Catalysis is already employed in many industries, but significant advances are needed to develop more effective catalytic processes for industry-relevant catalyzed reactions. Thus, the group will make and study new metal-based catalysts designed so that the catalytic metal ion is supported within a polymer scaffold intended to control the immediate environment of that metal ion to enhance reactivity, longevity, selectivity, tolerance, and ease of separation after the reaction. A set of testing conditions will be determined using a previously reported metal-based catalyst (without the polymer scaffold) as reaction benchmark, thereby allowing direct comparison of the results with what has come before to deconvolute the impact of the polymer, and to share these benchmarks with other researchers investigating their own novel catalysts for these reactions. The reactions chosen for focus have applications in a range of industries including fuel production, pharmaceuticals, agriculture, and wastewater treatment. These reactions currently face challenges related to product selectivity, catalyst lifetime, and limitations to the conditions under which the reactions can be run due to the tolerances of the catalyst, motivating further innovations in catalyst design. The broader impacts of this project will be the advancement of catalysis in these areas, the fundamental studies of supported catalysts, determining standard conditions to test and compare the reactivity of novel catalysts with previously reported complexes, training and research opportunities for SJSU undergraduate and Master’s students, training and research opportunities for students from nearby community colleges thereby building a pipeline for these community college students to transfer to SJSU, and forwarding collaborations between R1 institutions and SJSU. It is essential to study catalysts under consistent conditions to achieve consistent and comparable results. Though all of the reactions targeted in this study have precedent, different groups are not necessarily testing their complexes using the same conditions. This work will determine effective testing conditions for three reactions of interest: iridium-catalyzed alkane dehydrogenation, ruthenium-catalyzed cross metathesis, and iron-catalyzed electrocatalytic nitrate and nitrite reduction. These conditions will then be applied to the supported complexes that comprise the other half of this project. The Radlauer research group has previously synthesized core cross-linked star polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization using an “arm-first” method that allows for the direct incorporation of a ligand precursor into the core the star polymer. Metalation of these star polymers will lead to the formation of confined catalysts that can be tested using the standardized catalysis reactions to be developed with previously reported small molecule analogues. The comparison of the small molecule benchmark with the supported catalysts will allow a measure of the impact of the polymer scaffold in each of the reactions of interest and to iterate on the polymer structure to enhance the catalytic performance. 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.