Caradonna Group Receives NSF Research Award
Prof. John Caradonna and his group have received a 3-year National Science Foundation award from the Chemical Catalysis (CAT) Program in the Division of Chemistry (2013-2016). Entitled “Utilizing Iron-Coenzyme Oxygen Activation in Catalysis,” the project aims to investigate new oxidation processes that directly use dioxygen in sustainable metal-based systems that preclude non-selective free-radical chain reactions. The area of catalytic alkane oxidation and functionalization is of intense scientific and commercial interest because of its potential to convert inexpensive aliphatic hydrocarbons to valuable chemical and fuel products.
This project aims to develop and characterizes a family of biologically inspired mononuclear iron complexes that utilize dioxygen in the production of an iron-based reactive species that can catalytically oxidize carbon-hydrogen (C-H) bonds in the presence of sacrificial two-electron donor ligands such as α-keto acids (e.g., α-ketoglutarate). The research focuses on two fundamentally different, although related aspects of alkane oxidation: 1) the development of a molecular-level understanding of the mechanism by which these mononuclear non-heme ferrous complexes activate dioxygen to form a metal-based oxidant, and 2) the creation of second-generation complexes that will support the general synthetic use of the formal oxygen-atom transfer reactivity properties of these systems.
The researchers will combine state-of-the-art experimental (low temperature [-85 oC] stopped-flow kinetic studies, mechanistic investigations utilizing isotopicallylabeled and/or radical clock substrates), spectroscopic studies (flow resonance Raman, rapid-freeze quench Mössbauer and X-ray absorption spectroscopy), and computational simulations to characterize the mechanistic steps. This approach will enable them to develop catalysts with enhanced and selective reactivity properties. The use of iron in these catalytic systems is particularly attractive as this metal is earth-abundant and non-toxic. Thus this effort will open new avenues to inexpensive and sustainable catalytic transformations of interest to industry. Overall, the Caradonna Group aims to achieve a deeper understanding of fundamental reaction chemistry that could lead to the development of useful reagents for the controlled oxidation of substrates such as alkanes and arenas.