| Summary: | 碩士 === 國立交通大學 === 生物科技系所 === 102 === Hydrogen, a gaseous energy, has recently become a trend in alternative energy research. In nature, hydrogenases (H2ase) can catalyze reversible hydrogen reduction of proton (H++2e-↔H2). The active site of [FeFe]H2ase called the H-cluster, which includes 2Fe2S subunit. The structure of the 2Fe2S subunit is a dithiolate-bridged diiron complex and has been used as a biomimetic photochemical catalyst for light-driven hydrogen generation.
Our aim is to mimic the structure of the H-cluster. We take ruthenium substitutes for the central metal iron and take eight different P-ligands with different electronic and steric effects to substitute for the CO ligand of H-cluster to synthesize ruthenium-phosphine H-clusters. In this research, ruthenium-phosphine H-clusters, Ru-HP1, Ru-HP2, Ru-HP3, Ru-HP4, Ru-HP5, Ru-HP6, Ru-HP7, and Ru-HP8 are synthesized and characterized by single crystal X-ray structure determination. The hydrogen generation efficiency of eight ruthenium-phosphine H-clusters were compared with Ru-H with non-covalently linked P-ligands and were applied as catalysts in light-driven hydrogen generation from different proton sources such as water and formic acid. The results show that hydrogen generation obtained from formic acid is better than that obtained from water. In the organic phase, the P-ligands with an electron donating functional group has higher hydrogen generation efficiency than the P-ligands with an electron withdrawing functional group. For ruthenium-phosphine H-clusters, Ru-HP4 had the better efficiency (TOF is 6447 after three hours of irradiation) than Ru-H in the presence of P(o-tol)3 (TOF is 5532 after
three hours of irradiation). Ru-HP4 in the presence of a different ratio of P(o-tol)3 influenced the hydrogen generation efficiency. The Ru-HP4/P(o-tol)3 (1:1) had the best efficiency (a TOF of 8305) after three hours of photoirradiation. The mechanism for the organic phase was proposed after 31P NMR analyses were performed. From the catalytic mechanism for hydrogen generation, P(o-tol)3 (a substitute in the catalytic cycle) and Ru-H (a recycling photocatalyst in the catalytic cycle) could not be consumed in this system. In the future, ruthenium-phosphine H-clusters are promising catalysts in the light-driven hydrogen production industry.
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