CNRS Chemistry of Biological Processes Laboratory

Paris, France

CNRS Chemistry of Biological Processes Laboratory

Paris, France
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Fogeron T.,CNRS Chemistry of Biological Processes Laboratory | Retailleau P.,CNRS Natural Product Chemistry Institute | Chamoreau L.-M.,University of Paris Descartes | Fontecave M.,CNRS Chemistry of Biological Processes Laboratory | Li Y.,CNRS Chemistry of Biological Processes Laboratory
Dalton Transactions | Year: 2017

The reduction of the dithiolene ligand, qpdt2−, a mimic of the biological molybdopterin cofactor, and the corresponding (η5-cyclopentadienyl)cobalt(iii) complex [(qpdt)CoIIICp] was studied. It was found that in both cases an unprecedented ring scission reaction took place in acidic medium. All new reaction products have been spectroscopically and structurally characterized. Plausible mechanisms for the formation of these products were also proposed. © The Royal Society of Chemistry.

Huan T.N.,CNRS Chemistry of Biological Processes Laboratory | Rousse G.,Collège de France | Rousse G.,Paris-Sorbonne University | Zanna S.,Chimie Paristech | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2017

To use water as the source of electrons for proton or CO2 reduction within electrocatalytic devices, catalysts are required for facilitating the proton-coupled multi-electron oxygen evolution reaction (OER, 2 H2O→O2+4 H++4 e−). These catalysts, ideally based on cheap and earth abundant metals, have to display high activity at low overpotential and good stability and selectivity. While numerous examples of Co, Mn, and Ni catalysts were recently reported for water oxidation, only few examples were reported using copper, despite promising efficiencies. A rationally designed nanostructured copper/copper oxide electrocatalyst for OER is presented. This material derives from conductive copper foam passivated by a copper oxide layer and further nanostructured by electrodeposition of CuO nanoparticles. The generated electrodes are highly efficient for catalyzing selective water oxidation to dioxygen with an overpotential of 290 mV at 10 mA cm−2 in 1 m NaOH solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Hamdane D.,CNRS Chemistry of Biological Processes Laboratory | Bou-Nader C.,CNRS Chemistry of Biological Processes Laboratory | Cornu D.,French Institute of Health and Medical Research | Fontecave M.,CNRS Chemistry of Biological Processes Laboratory
Biochemistry | Year: 2015

Enzyme-catalyzed reactions often rely on a noncovalently bound cofactor whose reactivity is tuned by its immediate environment. Flavin cofactors, the most versatile catalyst encountered in biology, are often maintained within the protein throughout numbers of complex ionic and aromatic interactions. Here, we have investigated the role of π-π stacking and hydrogen bond interactions between a tyrosine and the isoalloxazine moiety of the flavin adenine dinucleotide (FAD) in an FAD-dependent RNA methyltransferase. Combining several static and time-resolved spectroscopies as well as biochemical approaches, we showed that aromatic stacking is assisted by a hydrogen bond between the phenol group and the amide of an adjacent active site loop. A mechanism of recognition and binding of the redox cofactor is proposed. (Graph Presented). © 2015 American Chemical Society.

Ciantar M.,French Institute of Petroleum | Mellot-Draznieks C.,CNRS Chemistry of Biological Processes Laboratory | Nieto-Draghi C.,French Institute of Petroleum
Journal of Physical Chemistry C | Year: 2015

A kinetic Monte Carlo (kMC) approach combined with density functional theory (DFT) calculations is used to examine the effects of molecular diffusion and synthesis parameters (pH 7-12) as well as initial monomer concentration (0.01-1 mol L-1) for a silicate oligomerization model. To implement this approach, we have adapted the open source kMC SPPARKS software in order to simulate the early stages involved in zeolite formation and more generally kinetically driven reactional systems, using a variety of lattice models (fcc/octahedral/tetrahedral, i.e., fcc/oct/tet). First, these adaptations were validated with kinetically driven reactional systems of the "Lodka" model, providing an excellent match with the analytical solution of the reactive system. The calculations reveal that both the lattice complexity and the diffusion coefficients of species have an impact on the steady state concentration (ssc) of oligomers in solution. Second, the approach is further applied to the early stages of silicate oligomerization using chemical pathways (activation barriers and associated prefactors) taken from the literature. Besides the expected impact of key input parameters (amplitudes of energy barriers, influence of water molecules in reaction pathways, pH, etc.), we demonstrate the impact of diffusion (viscosity of the clear solution) on the ssc of silicate oligomers. Considering that the kMC model is limited by the frequencies of reactional rare events, we find that when diffusional frequencies are much larger than reactional ones, the system diffuses instead of reacting. In that respect our calculations suggest that the magnitude of the diffusion coefficient determines the relative ssc of cyclic vs linear oligomers with a transition regime around of 10-14 m2 s-1 under the reaction conditions studied here (pH 9, 350 K, and initial concentration of 1 mol L-1). © 2015 American Chemical Society.

Aussel L.,Aix - Marseille University | Pierrel F.,CNRS Chemistry and Biology of Metals Laboratory | Loiseau L.,Aix - Marseille University | Lombard M.,CNRS Chemistry of Biological Processes Laboratory | And 2 more authors.
Biochimica et Biophysica Acta - Bioenergetics | Year: 2014

Ubiquinone, also called coenzyme Q, is a lipid subject to oxido-reduction cycles. It functions in the respiratory electron transport chain and plays a pivotal role in energy generating processes. In this review, we focus on the biosynthetic pathway and physiological role of ubiquinone in bacteria. We present the studies which, within a period of five decades, led to the identification and characterization of the genes named ubi and involved in ubiquinone production in Escherichia coli. When available, the structures of the corresponding enzymes are shown and their biological function is detailed. The phenotypes observed in mutants deficient in ubiquinone biosynthesis are presented, either in model bacteria or in pathogens. A particular attention is given to the role of ubiquinone in respiration, modulation of two-component activity and bacterial virulence. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. © 2014 Elsevier B.V.

Elgrishi N.,CNRS Chemistry of Biological Processes Laboratory | Chambers M.B.,CNRS Chemistry of Biological Processes Laboratory | Artero V.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,CNRS Chemistry of Biological Processes Laboratory
Physical Chemistry Chemical Physics | Year: 2014

Homoleptic terpyridine complexes of first row transition metals are evaluated as catalysts for the electrocatalytic reduction of CO2. Ni and Co-based catalytic systems are shown to reduce CO2 to CO under the conditions tested. The Ni complex was found to exhibit selectivity for CO2 over proton reduction while the Co-based system generates mixtures of CO and H2 with CO:H2 ratios being tuneable through variation of the applied potential. This journal is © the Partner Organisations 2014.

Chambers M.B.,CNRS Chemistry of Biological Processes Laboratory | Wang X.,CNRS Chemistry of Biological Processes Laboratory | Elgrishi N.,CNRS Chemistry of Biological Processes Laboratory | Hendon C.H.,University of Bath | And 7 more authors.
ChemSusChem | Year: 2015

The first photosensitization of a rhodium-based catalytic system for CO2 reduction is reported, with formate as the sole carbon-containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H2-storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post-synthetic linker exchange, and characterization of a new metal-organic framework (MOF) Cp Rh@UiO-67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF-based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of∼10% molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H2. There is no precedent for a MOF catalyzing the latter reaction so far. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA Weinheim.

Mellot-Draznieks C.,CNRS Chemistry of Biological Processes Laboratory
Molecular Simulation | Year: 2015

The purpose of this article is to consider some recent developments in the area of the computational chemistry of metal-organic frameworks (MOFs), and more specifically on their crystal structure prediction and electronic structures. We intend here to illustrate how computational approaches might be powerful tool for the discovery of new families of hybrid frameworks, helping to understand their often complex energy landscapes. Also, MOFs have attracted a lot of attention due to their potential use for photocatalysis and optoelectronic, making it necessary to develop strategies to control their electronic structures. We will show how recent computational studies in this area have allowed a better understanding of their electronic properties and their potential tunability, highlighting when they have given successful guidelines for the discovery of novel MOFs with targeted properties. © 2015 Taylor & Francis.

Bouden S.,University Paris Diderot | Gomez-Mingot M.,University Paris Diderot | Gomez-Mingot M.,CNRS Chemistry of Biological Processes Laboratory | Randriamahazaka H.,University Paris Diderot | Ghilane J.,University Paris Diderot
Analytical Chemistry | Year: 2016

A simple and general route for the immobilization of molecules containing ionic liquids framework was described. The proposed approach is inspired from the classical synthesis of ionic liquid and labeled surface-initiated synthesis of molecules bearing ionic liquid components. In the first step, bromide end layer was electrochemically grafted onto the electrode surface followed by its reaction with imidazole derivatives. The generated modified materials were characterized by electrochemistry and by X-ray photoelectron spectroscopy (XPS). As a result, molecule-based ionic liquids were successfully attached onto electrode material. The possibility to perform an anion-exchange reaction within the layer was demonstrated. Furthermore, the proposed surface functionalization approach was successfully performed without requiring the synthesis of any intermediate. The generated structures provide multifunctional systems containing ions, immobilized cation and mobile anion, and redox species. © 2015 American Chemical Society.

Elgrishi N.,CNRS Chemistry of Biological Processes Laboratory | Chambers M.B.,CNRS Chemistry of Biological Processes Laboratory | Fontecave M.,CNRS Chemistry of Biological Processes Laboratory
Chemical Science | Year: 2015

Understanding the activity and selectivity of molecular catalysts for CO2 reduction to fuels is an important scientific endeavour in addressing the growing global energy demand. Cobalt-terpyridine compounds have been shown to be catalysts for CO2 reduction to CO while simultaneously producing H2 from the requisite proton source. To investigate the parameters governing the competition for H+ reduction versus CO2 reduction, the cobalt bisterpyridine class of compounds is first evaluated as H+ reduction catalysts. We report that electronic tuning of the ancillary ligand sphere can result in a wide range of second-order rate constants for H+ reduction. When this class of compounds is next submitted to CO2 reduction conditions, a trend is found in which the less active catalysts for H+ reduction are the more selective towards CO2 reduction to CO. This represents the first report of the selectivity of a molecular system for CO2 reduction being controlled through turning off one of the competing reactions. The activities of the series of catalysts are evaluated through foot-of-the-wave analysis and a catalytic Tafel plot is provided. This journal is © The Royal Society of Chemistry.

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