Electron and proton transfers at diiron dithiolate sites relevant to the catalysis of proton reduction by the [FeFe]-hydrogenases

Capon, Jean‐François; Gloaguen, Frédéric; Pétillon, François Y.; Schollhammer, Philippe; Talarmin, Jean

doi:10.1016/j.ccr.2008.10.020

Cited by 298 publications

(203 citation statements)

References 209 publications

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“…Examples of molybdenum-and iron-based catalysts have also been reported. [14][15][16] Significant advances have been realized with iron-thiolate complexes of the type [Fe 2 (m-SRS)(CO) 6Àx L x ] (R= organic group, L = electron-donor ligand, x 4), [17][18][19][20][21][22][23][24][25] which are simplified models of the Fe 2 S 2 subunit of iron-iron hydrogenase enzymes. [26] The utilization of these iron-thiolate complexes for visible light-driven H 2 production has been recently reviewed.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

2013

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International audienceIron–thiolate complexes of the type [Fe2(μ-bdt)(CO)6−xP(OMe3)x] (bdt=S2C6H4=benzenedithiolate, x≤2) are simplified models of iron–iron hydrogenase enzymes. Recently, we have shown that these water-insoluble organometallic complexes, when included into micelles formed by sodium dodecyl sulfate (SDS), are good catalysts for the electrochemical production of hydrogen in aqueous solutions at pH<6. We herein report that the all-CO derivative [Fe2(μ-bdt)(CO)6] (1), owing to its comparatively low reduction potential, is also a robust molecular catalyst for visible-light-driven production of H2 in aqueous SDS solutions at pH 10.5. Irradiation at λ=455 nm of a system consisting of complex 1, Eosin Y as a sensitizer, and triethylamine as an electron donor produced up to 0.86 mL of H2 in 4.5 h, corresponding to a turnover number of 117 mol of H2 per mol of catalyst. In the presence of a large excess of sensitizer, the production of H2 lasted for more than 30 h, stressing the relative stability of complex 1 under the photocatalytic conditions used herein. Thermodynamic considerations and UV/Vis spectroscopy experiments suggest that the catalytic cycle begins with the photo-driven reduction of complex 1. The reduced intermediate reacts with a proton source to yield iron hydride. Subsequent reduction and protonation steps produce H2, regenerating the starting complex. As a result, the iron–thiolate complex 1 is a versatile proton reduction catalyst that can utilize either solar or electrical energy inputs, providing a starting point for the construction of noble metal-free molecular systems for renewable H2 production

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Section: Introductionmentioning

confidence: 99%

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

2013

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“…Diiron-dithiolate compounds of the type [Fe 2 (µ-SRS)(CO) 6-x L x ] (R = organic group, L = electron-donor ligand, x ≤ 4) have been shown to electrocatalyze the reduction of acid in organic solvents [19][20][21] and, very recently, in aqueous micellar solutions [22,23](for examples of photo-driven H 2 -production by diiron-dithiolate compounds see [24,25]). The electrocatalytic pathway entails successive electron and proton transfers in a sequence that depends on the nature of the terminal ligand L and the strength of the acid used as proton source [16,26] We [27][28][29][30][31][32], and others [33][34][35][36][37] [27,28].…”

Section: Introductionmentioning

confidence: 99%

Kinetic and thermodynamic aspects of the electrocatalysis of acid reduction in organic solvent using molecular diiron-dithiolate compounds

Quentel

Gloaguen

2013

Electrochimica Acta

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To cite this version:Francois Quentel, Frederic Gloaguen. Kinetic and thermodynamic aspects of the electrocatalysis of acid reduction in organic solvent using molecular diiron-dithiolate compounds. 2015. AbstractIn an attempt to obtain molecular H 2 production electrocatalysts achieving balanced basicity and reduction potential, we focused on the mono-substituted diiron-dithiolate derivative [Fe 2 (µ-bdt)(CO) 5 (P(OMe) 3 )] (bdt = benzenedithiolate). The electrocatalytic efficiency of this iron-iron hydrogenase model was determined by cyclic voltammetry in acetonitrile using ptoluenesulfonic acid as a proton source. Detailed analysis of the current -potential responses and comparison with the all-CO diiron-dithiolate parent compound clearly show that the effect of the chemical properties on the electrocatalytic efficiency is not fully determined by the turnover frequency under pseudo-first-order approximation and the overpotential defined as the difference between the reduction potential of the electrocatalysts in the absence of acid and the reversible potential of the couple H 2 /acid.

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“…Over the past decade, a variety of mimics of the diiron subsite of [FeFe]-H 2 ase have been shown to function as catalysts for chemical reduction of protons [26][27][28][29][30][31][32][33] . It has been clear that electron transfer, either electrochemical or photochemical, to a mimic of the active site of [FeFe]-H 2 ase is a prerequisite for H 2 evolution [10][11][12][13][14]22 . From a photochemical point of view, the electron transfer is triggered by the absorption of a photon by a photosensitizer [13][14][15][16][17][18][19][20][21][22][23][24][25] .…”

mentioning

confidence: 99%

“…The astonishing rates of H 2 production from the non-precious diiron catalysts via a group of enzymes under mild conditions can exceed those of platinum. However, the large-scale isolation of the enzyme from natural systems is rather difficult, hence the development of artificial [FeFe]-H 2 ase analogues capable of reproducing the enzymic activity has spurred considerable interest in both the scientific and industrial communities [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] . Over the past decade, a variety of mimics of the diiron subsite of [FeFe]-H 2 ase have been shown to function as catalysts for chemical reduction of protons [26][27][28][29][30][31][32][33] .…”

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confidence: 99%

Chitosan confinement enhances hydrogen photogeneration from a mimic of the diiron subsite of [FeFe]-hydrogenase

et al. 2013

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Nature has created [FeFe]-hydrogenase enzyme as a hydrogen-forming catalyst with a high turnover rate. However, it does not meet the demands of economically usable catalytic agents because of its limited stability and the cost of its production and purification. Synthetic chemistry has allowed the preparation of remarkably close mimics of [FeFe]-hydrogenase but so far failed to reproduce its catalytic activity. Most models of the active site represent mimics of the inorganic cofactor only, and the enzyme-like reaction that proceeds within restricted environments is less well understood. Here we report that chitosan, a natural polysaccharide, improves the efficiency and durability of a typical mimic of the diiron subsite of [FeFe]-hydrogenase for photocatalytic hydrogen evolution. The turnover number of the self-assembling system increases B4,000-fold compared with the same system in the absence of chitosan. Such significant improvements to the activity and stability of artificial [FeFe]-hydrogenase-like systems have, to our knowledge, not been reported to date.

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Electron and proton transfers at diiron dithiolate sites relevant to the catalysis of proton reduction by the [FeFe]-hydrogenases

Cited by 298 publications

References 209 publications

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

Photocatalytic Hydrogen Production Using Models of the Iron–Iron Hydrogenase Active Site Dispersed in Micellar Solution

Kinetic and thermodynamic aspects of the electrocatalysis of acid reduction in organic solvent using molecular diiron-dithiolate compounds

Chitosan confinement enhances hydrogen photogeneration from a mimic of the diiron subsite of [FeFe]-hydrogenase

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