Approaches to efficient molecular catalyst systems for photochemical H-2 production using [FeFe]-hydrogenase active site mimics
ABSTRACT The research on structural and functional biomimics of the active site of [FeFe]-hydrogenases is in an attempt to elucidate the mechanisms of H(2)-evolution and uptake at the [FeFe]-hydrogenase active site, and to learn from Nature how to create highly efficient H(2)-production catalyst systems. Undoubtedly, it is a challenging, arduous, and long-term work. In this perspective, the progresses in approaches to photochemical H(2) production using mimics of the [FeFe]-hydrogenase active site as catalysts in the last three years are reviewed, with emphasis on adjustment of the redox potentials and hydrophilicity of the [FeFe]-hydrogenase active site mimics to make them efficient catalysts for H(2) production. With gradually increasing understanding of the chemistry of the [FeFe]-hydrogenases and their mimics, more bio-inspired proton reduction catalysts with significantly improved efficiency of H(2) production will be realized in the future.
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ABSTRACT: The description of the electronic structure and magnetic properties of multi-centers transition metal complexes, especially of mixed-valence compounds, still represents a challenge for density functional theory (DFT) methods. The energies and the geometries of the correctly symmetrized low-spin ground state are estimated using the Heisenberg-Dirac-van Vleck spin Hamiltonian within the extended broken symmetry method introduced by Marx and co-workers [Nair et al., J. Chem. Theory Comput. 4, 1174–1188 (2008)10.1021/ct800089x]. In the present work we extend the application of this technique, originally implemented using the DFT+U scheme, to the use of hybrid functionals, investigating the ground-state properties of di-iron and di-manganese compounds. The calculated magnetic coupling and vibrational properties of ferredoxin molecular models are in good agreements with experimental results and DFT+U calculations. Six different mixed-valence Mn(III)–Mn(IV) compounds have been extensively studied optimizing the geometry in low-spin, high-spin, and broken-symmetry states and with different functionals. The magnetic coupling constants calculated by the extended broken symmetry approach using B3LYP functional presents a remarkable agreement with the experimental results, revealing that the proposed methodology provides a consistent and accurate DFT approach to the electronic structure of multi-centers transition metal complexes.The Journal of Chemical Physics 01/2012; 137(11-11):114107-114107-7. DOI:10.1063/1.4752398 · 3.12 Impact Factor
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ABSTRACT: A membrane electrode assembled with electrospun-fibers derived from a composite of cellulose acetate (CA) functionalised with carboxylated multiwall carbon nanotubes (cMWCNTs), polyvinyl pyrrolidone (PVP), and diiron model ([Fe2(edt)(CO)6], edt = ethanedithiolate) catalyses proton reduction in water with the presence of acetic acid.RSC Advances 01/2012; 2(27):10171. DOI:10.1039/c2ra21036c · 3.84 Impact Factor
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