Yong Na

Light-driven hydrogen production catalysed by transition metal complexes in homogeneous systems

The development of heterogeneous catalytic systems for hydrogen production from water under light irradiation has been investigated during last three decades. Homogeneous photocatalysts, however, are very attractive in sense that their chemical and photochemical properties can be understood and tuned on molecular level. Moreover, in homogeneous systems catalysts may be covalently bound to photosensitizers, which leads to more efficient electron transfer. Molecular devices for water splitting based on such a systems are of great interest. In this review, we summarize recent progresses in the synthesis, properties and application of metal-based molecular catalysts for photoinduced hydrogen evolution in homogeneous systems.

Visible Light-Driven Electron Transfer and Hydrogen Generation Catalyzed by Bioinspired [2Fe2S] Complexes

Complexes [{(mu-SCH2)2NCH2C6H5}{Fe(CO)2L(1)}{Fe(CO)2L(2)}] (L(1) = CO, L(2) = P(Pyr) 3, 2; L(1) = L(2) = P(Pyr)3, 3) were prepared, which have the lowest reduction potentials for the mono- and double-CO-displaced diiron complexes reported so far. Hydrogen evolution, driven by visible light, was successfully observed for a three-component system, consisting of a ruthenium polypyridine complex, the biomimetic model complex 2 or 3, and ascorbic acid as both electron and proton donor in CH3CN/H2O. The electron transfer from photogenerated Ru(bpy)3(+) to 2 or 3 was detected by laser flash photolysis. Under optimal conditions, the total turnover number for hydrogen evolution was 4.3 based on 2 and 86 based on Ru(bpy)3(2+) in a three-hour photolysis.

Noncovalent assembly of a metalloporphyrin and an iron hydrogenase active-site model : Photo-induced electron transfer and hydrogen generation

A noncovalent assembly of a pyridyl-functionalized hydrogenase active-site model complex and zinc tetraphenylporphyrin has been obtained and characterized. Upon light irradiation, fluorescence quenching by electron transfer was observed from the singlet excited state of the porphyrin to the diiron center, and the mechanism was verified by fluorescence lifetime and transient absorption spectroscopic measurements. In contrast to molecular dyads linked by covalent bonds, the assembled system was designed to avoid charge recombination via complex dissociation after photo-induced electron transfer. Visible light-driven hydrogen generation was observed from this self-assembled system. The assembling strategy employed in this study has the potential to be used for any other hydrogenase models in the future.

Visible light driven H2 production in molecular systems employing colloidal MoS2 nanoparticles as catalyst

Colloidal MoS(2) nanoparticles with diameters of less than 10 nm were prepared with a simple solvothermal method and demonstrated high efficiency in catalyzing H(2) evolution in Ru(bpy)(3)(2+)-based molecular systems under visible light.

Synthesis of chiral salen Mn(III) complexes covalently linked to Re(I)-based photosensitizers

Two Mn(III)Re(I) binuclear complexes were prepared as catalyst-photosensitizer models, in which the chiral pyrrolidine salen Mn(III) unit was covalently bonded to an Re(I) bipyridyl carbonyl moiety via a carboxamide linkage. The spectral and electrochemical properties of the Mn(III)Re(I) complexes were studied. *Corresponding authors. Tel.: +86-411-88993886. Fax: +86-411-83702185. Email: symbueno@vip.sina.com