RUI: Mechanistic Investigation of Photochemical Products from Iron-Iron Hydrogenase Model Compounds; Insight into the Catalytic Generation and Activation of Molecular Hydrogen

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Professor Carmen Works is supported by the Chemical Catalysis (CAT) Program in the Division of Chemistry to conduct research at Sonoma State University to elucidate the mechanism of iron-iron hydrogenase model compounds. Iron-iron hydrogenase is an organometallic enzyme that catalyzes the reversible oxidation of molecular hydrogen. The detrimental effects of fossil fuel usage on our global ecosystem as well as ever increasing energy demands have inspired much research towards the development of clean and renewable fuels. Hydrogen is seen as an ideal carbon-free energy source as its only combustion product is water. Unfortunately, the best catalysts for hydrogen generation and usage are based on the rare and very expensive platinum metal, presenting a significant economic obstacle for the large-scale production of hydrogen to meet our energy demands. However, Nature has provided efficient and robust Earth rich metal enzymes, that are able to produce hydrogen cleanly. Due to the potential importance and utility of this natural process, the present work is focused on understanding the catalytic chemistry that occurs in these enzymes in order to advance the design of new and inexpensive technological systems for hydrogen use. The approach in this project is to make small organometallic molecules that are both structural and functional models of the enzyme active site and to use spectroscopic and kinetic techniques to characterize their photochemical and thermal reactivity. The working hypothesis is that light produces the active catalysts in solution. This work is leading to a deeper understanding of the fundamental reactivity. The strategy used in this proposal is to synthesize a range of molecules that vary in both electronic and steric properties but have the general di-iron core, and to study the photochemistry under CO and H2. In addition, the thermal reactivity of the photoproducts with hydrogen as a function of solvent is being studied to understand catalysis. Experimental results are being compared with theoretical calculations. In addition, this project has a large educational impact and is providing training in the area of inorganic synthesis, spectroscopy, catalysis, photochemistry and exposed undergraduate students to theoretical chemistry. Outreach to both the scientific and local community is including undergraduate students specifically through presentations at regional and National meetings and publications.