Synthèse de polyoxométallates fonctionnalisés à propriétés optiques ou magnétiques

Plusieurs polyoxotungstates de type sandwich ont été synthétisés tant à pression atmosphérique qu en conditions hydrothermales. Parmi eux, un nouveau complexe au chrome vient compléter la famille jusqu alors très restreinte des polyanions incorporant ce métal, tandis que plusieurs complexes au fer sont remarquables pour leurs propriétés magnétiques, certains présentant un comportement d aimant moléculaire. Parallèlement divers sels combinant un polyanion avec un chromophore cationique de type stilbazolium ou spiropyrane ont été cristallisés. Les propriétés de ceux-ci ont été étudiées en photochromisme, électrochromisme ou optique non linéaire. Enfin, la réaction de précurseurs de molybdène au degré +V ou +VI avec des ligands diphosphonates fonctionnalisés a mené à des architectures cycliques inédites. Leur comportement en solution, leur application à la synthèse de nanoparticules et, pour les composés au molybdène(VI), leurs propriétés photochromes, ont été analysés.Several sandwich-type polyoxotungstates have been synthesized either at atmospheric pressure or under hydrothermal conditions. Amongst them a new chromium complex has enlarged the so far underdeveloped family of polyanions incorporating this metal, while several iron complexes have proved remarkable for their magnetic properties, some behaving as single-molecule magnets. Besides, various salts combining a polyanion and a cationic chromophore like a stilbazolium or a spiropyran have been crystallized. Their properties in photochromism, electrochromism or non-linear optics have been studied. Eventually, the reaction of molybenum(V) or molybdenum(VI) precursors with functionalized bisphosphonates has led to unprecedented architectures. Their behaviour in solution, their application towards the synthesis of nanoparticles and, concerning molybdenum(VI) compounds, their photochromic properties, have been investigated.VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF

Electro and photoreduction of CO 2 driven by manganese-carbonyl molecular catalysts

International audienc

Electro and photoreduction of CO 2 driven by manganese-carbonyl molecular catalysts

International audienc

Manganese carbonyl terpyridyl complexes: their synthesis, characterization and potential application as CO-release molecules

International audienc

A Polyoxometalate–Cyanometalate Multilayered Coordination Network

The reaction of the ε-Keggin polyoxometalate (POM) [PMo₁₂O₃₆(OH)₄{La­(H₂O)₄}₄]⁵⁺ with Fe^II(CN)₆^4– under typical bench conditions at room temperature and ambient pressure has afforded the novel [ε-PMo₁₂O₃₇(OH)₃{La­(H₂O)₅(Fe­(CN)₆)_0.25}₄] network, which exhibits a three-dimensional multilayered structure. The compound has been fully characterized by synchrotron-radiation X-ray crystallography, IR spectroscopy, elemental analysis, and thermogravimetric analysis. This coordination network constitutes the first example of a cyanometalate bonded to a POM unit

Selective Catalytic Electroreduction of CO2 at Silicon Nanowires (SiNWs) Photocathodes Using Non-Noble Metal-Based Manganese Carbonyl Bipyridyl Molecular Catalysts in Solution and Grafted onto SiNWs

International audienceThe electrocatalytic redn. of CO2 to CO in hydroorg. medium has been investigated at illuminated (λ \textgreater 600 nm; 20 mW cm-2) hydrogen-terminated silicon nanowires (SiNWs-H) photocathodes using three Mn-based carbonyl bipyridyl complexes as homogeneous mol. catalysts ([Mn(L) (CO)3(CH3CN)](PF6) and [Mn(bpy) (CO)3Br] with L = bpy = 2,2'-bipyridine and dmbpy = 4,4'-dimethyl-2,2'-bipyridine). Systematic comparison of their cyclic voltammetry characteristics with those obtained at flat hydrogen-terminated silicon and traditional glassy carbon electrodes (GCE) enabled us to demonstrate the superior catalytic efficiency of SiNWs-H in terms of cathodic photocurrent densities and overpotentials. For example, the photocurrent densities measured at -1.0 V vs SCE for [Mn(bpy) (CO)3(CH3CN)](PF6) at SiNWs-H exceeded 1.0 mA cm-2 in CO2-satd. CH3CN + 5% vol./vol. H2O, whereas almost zero current was measured at this potential at GCE. Such characteristics have been supported by the energetic diagrams built for the different SiNWs\textbarMn-based catalyst interfaces. The fill factor FF and energy conversion efficiency η calcd. under catalytic conditions were higher for [Mn(bpy or dmbpy) (CO)3(CH3CN)](PF6) (FF = 0.35 and 0.34; η = 3.0 and 2.0%, resp.). Further preparative-scale electrolysis at SiNWs-H photocathode with Mn-based complex catalysts in electrolytic soln. evidenced the quant. conversion of CO2 to CO with a higher stability of the [Mn(dmbpy) (CO)3(CH3CN)](PF6) complex. Finally, in order to develop technol. viable electrocatalytic devices, the elaboration of SiNWs-H photoelectrodes modified with a Mn-based complex has been successfully achieved from an electropolymerizable catalyst, and it was shown that the electrocatalytic activity of the complex was retained after immobilization

Mn-carbonyl molecular catalysts containing a redox-active phenanthroline-5,6-dione for selective electro- and photoreduction of CO 2 to CO or HCOOH

International audienc

Structural, Magnetic, EPR, and Electrochemical Characterizations of a Spin-Frustrated Trinuclear Cr III Polyoxometalate and Study of Its Reactivity with Lanthanum Cations

International audienc

The candidate gene for the X-linked Kallmann syndrome encodes a protein related to adhesion molecules

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