Penn State iridium enzyme mimic runs oxygen chemistry with water as only waste

Phys.org reported that a Penn State-led team built a synthetic enzyme mimic that drives an oxygen-using reaction producing only water as waste, work published in the Journal of the American Chemical Society. Assistant professor Jonathan Kuo said oxygen powers many vital reactions but has an electronic configuration that slows reactions with organic matter unless enzymes rearrange its electrons. The mimic inserts an oxygen atom from dioxygen into an aromatic ring, expanding catechol's six-carbon ring into a seven-atom ring that is less stable and opens more synthetic options. The natural enzyme is extradiol dioxygenase. Catechol can be made from benzene; both are used industrially, and their stable rings limit what chemicals can be produced for plastics, polymers, and fibers. Each reaction of the mimic costs one molecule of oxygen and produces one molecule of water as waste. The team used iridium rather than the iron, cobalt, or manganese found in natural enzymes. Kuo said iridium resists unwanted reactions with oxygen, which can make mimics easier to build and potentially longer lasting than iron-based versions that can react with air. First author Alexander G. Arnette and Alexey Silakov also contributed. The paper carries DOI: 10.1021/jacs.5c23353. Kuo framed the goal as basic research toward cleaner industrial chemistry and pharmaceutical synthesis that leaves less harmful byproduct.