Metalloradical Catalysis for Selective Radical Reactions

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With this award, the Chemical Catalysis Program of the NSF Division of Chemistry is supporting the research of Professor Peter Zhang of Boston College. Professor Zhang is developing new metal complexes as catalysts for the synthesis of organic compounds. Most metal-catalyzed processes rely on what chemists call "polar reactivity" where reactions involve transfers or sharing of two electrons at a time. Professor Zhang develops "metalloradical catalysis" where reactions involve the transfer or sharing of only one electron at a time. Professor Zhang's new catalytic systems take advantage of the unique features of such radical reactions. In comparison with the typical need for rare and expensive metal ions for catalyzing two-electron polar reactions, the one-electron metalloradical reactions are carried out with catalysts based on earth-abundant and inexpensive transition metals such as cobalt. As such, this research is addressing important issues of sustainability in fine chemical manufacturing, and applications to biology, medicine, and materials. Professor Zhang is also promoting science among the general public by providing educational resources for K-12 teachers and stimulating scientific interests of K-12 students. In addition to scientific training for graduate students and postdoctoral researchers, Professor Zhang's laboratory provides first-hand research experiences to high school students and teachers as well as undergraduate students.Professor Zhang's research centers on establishing metalloradical catalysis as a fundamentally new approach for controlling reactivity and stereoselectivity of radical reactions. Metalloradical systems based on cobalt(II) complexes of chiral porphyrins are being developed to harness the full potential of homolytic radical chemistry. These new catalytic radical processes, which are both mechanistically distinctive and operationally attractive, are serving as valuable synthetic tools for the construction of organic compounds including biologically-important natural products and pharmaceutically-interesting small molecules. The concept of metalloradical catalysis, which aims at the full exploration of homolysis as a fundamental way for bond breaking and making, is having far-reaching impact on organic synthesis and is stimulating the development of new synthetic methods based on radical chemistry. The successful demonstration of cobalt-based metalloradical catalysis is prompting the identification of new metalloradical catalyst systems based on different combinations of open-shell metal ions and chiral ligands that can catalyze a broad range of stereoselective radical reactions. While this research focuses on generalizable synthetic methods, applications to synthetic targets, including targets that are group III metabotropic glutamate receptor agonists may have implications in the proper neuronal function of the brain. In addition, Professor Zhang is creating public educational materials entitled "The Colors of Life" presented to students in local K-12 schools. These educational materials are being made available for public access in PowerPoint format via the web.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.