CAREER: Main-Group Element Catalysis Enabled with Outer Functional Spheres of Molecular Catalysts

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With funding from the Chemical Catalysis program in the Division of Chemistry, Professor Jiang of the University of Cincinnati will create metal-free catalysts for carbon dioxide reduction and organohalide dehalogenation. The development of inexpensive and robust catalysts is an important step towards efficient production of chemicals and remediation of environmental pollutants. Traditionally, expensive and rare elements are employed to prepare the catalysts for small molecule conversion due to the high reactivity of the rare elements; however, these systems suffer from toxicity, low abundance, and high cost. In this project, the catalytic activity will be enhanced through the modification of molecular environment around the catalytic active site. Professor Jiang will actively engage a diverse group of underrepresented students in science, technology, engineering and mathematics (STEM) disciplines and the general public in outreach activities focused on chemistry of sustainability. In addition, Professor Jiang's group will develop and maintain an interactive, open-source website for foot-of-the-wave analysis, a powerful technique for evaluating the performance of electrocatalysts. The construction of the website will start soon and be integrated into Professor Jiang's research website for easy access by the community. The results of the proposed research will contribute to the achievement of energy-efficient conversion of abundant small molecules such as carbon dioxide and halogenated pollutants into value-added products, which is both scientifically challenging and strategically important for our society.This project will explore under-developed main-group element catalysis and aims to provide both mechanistic insight and a rational design framework concerning the roles of structural flexibility, pKa, and the size of outer functional spheres in the catalytic activity of tailored 3-dimensional molecular architectures. The proposed study focuses on using bifunctional ligands with redox activity along with outer functional spheres to compensate for the fact that main-group elements lack outer shell d-orbitals. Specifically, Group15-based catalysts using porphyrin ligands with a diverse set of outer functional spheres will be designed, synthesized, and evaluated for carbon dioxide reduction and organohalide dehalogenation. The catalytic performance of the main-group element-based catalysts will be compared to current transition metal-based counterparts. A combination of solution- and surface-based techniques, in conjunction with density-functional theory calculations, will be used to identify reaction intermediates and help elucidate the catalytic mechanism. This research seeks to enrich the understanding of how interactions between redox-active ligands with outer functional spheres and Group 15 elements can be used as a strategy for bond activation, and how the use of a ligand with an outer functional sphere enables Group 15 element catalysis.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.