Timothy Jackson

Nature uses metalloenzymes containing Mn, Fe, or Cu and oxidants such as molecular oxygen and hydrogen peroxide to carry out remarkable oxidative transformations that are both vital for life and fascinating from a fundamental perspective. Such reactions also serve as inspiration for synthetic chemists, as catalytic processes that utilize earth-abundant metals are less expensive and more environmentally benign than conventional process that employ precious-metals. Our research focuses on using synthetic model complexes to understand the chemical reactions that are critical to the function of both metalloenzymes and earth-abundant metal catalysts. These reactions include activation of dioxygen (O2) and hydrogen peroxide (H­2O2) and the cleavage of C-H and O-H bonds by high- and mid-valent metal-oxygen species. To achieve these goals, the Jackson lab uses a combination of i) synthetic and kinetic methods to generate and characterize the reactivity patterns of metal ion complexes, ii) detailed spectroscopic characterization of transition-metal species, and iii) computational chemistry. These combined efforts allow us to identify geometric and electronic properties of transition-metal complexes that influence chemical reactivity.

Spectroscopic methods used in our research include electronic absorption (UV-vis), electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and X-ray absorption (XAS) spectroscopies. We also employ NMR methods to probe the solution structures of paramagnetic complexes. These tools are particularly powerful when used in conjunction with computational methods, as they permit the characterization of the geometric and electronic structures of fleeting intermediates too unstable to be characterized using standard crystallographic methods. Our lab also used kinetic studies to probe the reaction mechanisms of our complexes. By applying this three-pronged approach to bio-inspired transition-metal complexes, we gain detailed insight into how nature uses molecular oxygen and earth-abundant metals to oxidize substrates and apply this knowledge to develop transition metal complexes that can perform green oxidation reactions.