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Aqueous Green Chemistry

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Dinuclear Ni(μ-H)Ru Complex
Science 2007,316, 585-587


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Artificial enzyme (Ni-Fe complex)
Science 2007, 316, 585.


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Water decomposition

In order to solve the most important problems of the 21st century, including energy, resource and environmental problems, biomimetics are needed to extract and apply the functional principles of life and to surpass conventional bioscience. We are studying "aqueous green chemistry," in which bio-inspired catalysts with excellent reaction selectivity and low environmental impact are developed.

Hydrogenase and Model Complex
Hydrogenase is an enzyme that catalyzes the conversion of molecular hydrogen to protons and electrons, and which also reversibly generates hydrogen from protons and electrons. Our laboratory identifies and isolates various new hydrogenases with high catalytic activity and high stability from a large volume of genomic information, and examines their properties in detail. Using these hydrogenase enzymes, we are conducting research on hydrogen activation in water, at room temperature and at normal pressure. We have successfully isolated certain hydrides and extracted electrons (as indicated in our press releases of April 27, 2007 and August 9, 2008) from hydrogen with a Ni(μ-H)Ru Complex (artificial enzyme) in water, at room temperature and at normal pressure.

Oxygen-Protein Complex and Model Complex
Photosynthesis extracts electrons from water by using solar energy. The reaction corresponds to the anode (the electrode through which electrons flow out) of water electrolysis. The active center is called an "oxygen-evolution complex" or OEC. OECs presumably have the structure of manganese clusters, but their detailed structure and mechanism of water decomposition have not yet been clarified. In our laboratory, we culture photosynthetic organisms, isolate OECs from the cultured media and examine their chemical properties. Through the use of OECs, we design and synthesize manganese complexes in order to study their catalytic functions in the water decomposition process.

Water Gas Shift Reaction and CO Dehydrogenase
CO2 is one of the most economical carbon sources that can be expected to replace oil or coal. The water-gas shift reaction (WGSR) is a useful chemical reaction that is capable of adjusting the ratio between "CO, H2O" and "CO2, H2." The reaction apparently progresses with formic acid (HCOOH) as an intermediate, but its mechanism is not yet fully understood. Our laboratory has proposed a new mechanism involving two molecules of formic acid ions (Organometallics 2005, 24, 4816-4823). By implementing carbon monoxide dehydrogenase (CODH), we will expand our studies on CO2 fixation.

Ultra-Thermophilic Aerobic Enzyme
Thermophilic aerobic microorganisms that exist in very hot water environments display more potential thermal endurance and oxygen durability than other enzymes that have been studied so far. Our laboratory is working on the identification and isolation of hydrogenase and photosynthetic oxygen-protein complexes that have these characteristics.

Biofunctional Chemistry, Department of Applied Chemistry
Professor Seiji Ogo
Associate Professor Takahiro Matsumoto
Assistant Professor Takeshi Yatabe
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