JEREMY SMITH, Ph.D.

Molecules such as O₂ and N₂ are potentially cheap and abundant feedstocks in applications as diverse as natural product synthesis and bioremediation technologies. Controlling the reactivity of these molecules in a selective manner remains a challenging problem. The high selectivity of metalloenzymes in catalyzing the reactions of these molecules under mild conditions serves as inspiration for research in the Smith group. We prepare transition metal complexes based on key features of metalloenzyme active sites to understand and replicate the activity of these catalysts.

The active site of O₂-bound naphthalene dioxygenase, with hydrogen bonding to dioxygen highlighted.

One topic of interest is the reactivity of the non-heme oxygenases, a family of iron-based metalloenzymes that catalyze a wide variety of oxidations. For example, the Rieske dioxygenases catalyze the cis-1,2-hydroxylation of arenes by molecular oxygen, and provide an environmentally friendly alternative to the traditional heavy-metal hydroxylation catalysts used in organic chemistry. Interestingly, the basic core structure at the active site of non-heme oxygenases is common to a wide variety of oxidations. We are intrigued by the possibility that hydrogen-bonding interactions around the active site play a crucial role in controlling enzymatic reactivity. Our approach is to explore the oxidation reactivity of iron complexes supported by ligands whose hydrogen-bonding ability can be modified. The long-term goals of this project include understanding the role played by hydrogen bonding in the reactivity of non-heme oxygenases, and developing catalysts to oxidize substrates under mild conditions.

Other research interests include nitrogen fixation by complexes containing redox-active ligands, approaches to using carbon dioxide as a chemical feedstock and the organometallic chemistry of heterobimetallic complexes.

Members of the group will typically gain experience with organic and inorganic (inert atmosphere) synthesis, spectroscopic characterization by NMR, UV-vis, EPR, IR, magnetochemistry and X-ray crystallography, and studies of mechanism by kinetics and other mechanistic probes.