title: Photocatalytic water reduction and study of the formation of Fe(i)Fe(0) species in diiron catalyst systems.
abstract: Noble-metal-free systems with bio-inspired diiron dithiolate mimics of the [FeFe]-hydrogenase active site, namely, [(μ-pdt)Fe(2) (CO)(5) L] [pdt=propanedithiolate; L=P(CH(2) OH)(3) (1), P(CH(3) )(3) (2)], as water reduction catalysts with xanthene dyes as photosensitizers and triethylamine as a sacrificial electron donor were studied for visible-light-driven water reduction to hydrogen. These systems display good catalytic activities with the efficiencies in hydrogen evolution of up to 226 turnovers for 1, if Eosin Y was used as the photosensitizer in an environmentally benign solvent (EtOH/H(2) O) after 15 h of irradiation (λ>450 nm) under optimal conditions. Under all of the conditions adopted, 1 that has a water soluble phosphine ligand, P(CH(2) OH)(3) displayed a higher efficiency than 2, which bears a PMe(3) ligand. The photoinduced electron transfer in the systems was studied using fluorescence, transient absorption, time-resolved UV/Vis, and in situ electron paramagnetic resonance (EPR) spectroscopy. A new electron-transfer mechanism is proposed for hydrogen evolution by these iron-based photocatalytic systems.
authors.affiliation: State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), 116012 Dalian, PR China.
authors.forename: Xueqiang
authors.initials: X
authors.lastname: Li
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Xiuna
authors.initials: X
authors.lastname: Wang
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Dong
authors.forename: Licheng
authors.initials: L
authors.lastname: Sun
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006864:Hydrogenase / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D014867:Water / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D009942:Organometallic Compounds; D014867:Water; D003035:Cobalt; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase