H Evolution at a Reduced Hybrid Polyoxometalate and Its Vanadium-Oxo Derivative Used as Molecular Models for Reducible Metal Oxides.

We herein report our investigations on the use of a tris-silanol-decorated polyoxotungstate, [SbWO(tBuSiOH)], as a molecular support model to describe the coordination of an isolated vanadium atom at metal oxides, focusing on the reactivity of the reduced derivatives in the presence of protons. Accumulation of electrons and protons at an active site is a main feature associated with heterogeneous catalysts able to conduct the (oxy)dehydrogenation of alkanes or alcohols. Our results indicate that two-electron reduced derivatives release H upon protonation, a reaction that probably takes place at the polyoxotungstic framework rather than at the vanadium center.

When Identification of the Reduction Sites in Mixed Molybdenum/Tungsten Keggin-Type Polyoxometalate Hybrids Turns Out Tricky.

The mixed molybdenum/tungsten Keggin-type polyoxometalate (POM) hybrid (TBA)[PWMoO{Sn(CHI)}] (TBA = -butylammonium) has been prepared by the reaction between [α-PWMoO] and [ClSn(CHI)] in dried acetonitrile, in the presence of tetra--butylammonium bromide. A further coupling reaction affords the ferrocenyl derivative (TBA)[PWMoO{Sn(CH)C≡C(CH)Fc}]. The POM hybrids have been thoroughly characterized by NMR and IR spectroscopies.

Supramolecular assemblies of organo-functionalised hybrid polyoxometalates: from functional building blocks to hierarchical nanomaterials.

This review provides a comprehensive overview of recent advances in the supramolecular organisation and hierarchical self-assembly of organo-functionalised hybrid polyoxometalates (hereafter referred to as hybrid POMs), and their emerging role as multi-functional building blocks in the construction of new nanomaterials. Polyoxometalates have long been studied as a fascinating outgrowth of traditional metal-oxide chemistry, where the unusual position they occupy between individual metal oxoanions and solid-state bulk oxides imbues them with a range of attractive properties ( solubility, high structural modularity and tuneable properties/reactivity). Specifically, the capacity for POMs to be covalently coupled to an effectively limitless range of organic moieties has opened exciting new avenues in their rational design, while the combination of distinct organic and inorganic components facilitates the formation of complex molecular architectures and the emergence of new, unique functionalities.

Modeling the Oxygen Vacancy at a Molecular Vanadium(III) Silica-Supported Catalyst.

Here we report on the use of a silanol-decorated polyoxotungstate, [SbWO( BuSiOH)] (1), as a molecular support to describe the coordination of a vanadium atom at a single-site on silica surfaces. By reacting [V(Mes)·thf] (Mes = 2,4,6-trimethylphenyl) with 1 in tetrahydrofuran, the vanadium(III) derivative [SbWO( BuSiO)V(thf)] (2) was obtained. Compound 2 displays the paramagnetic behavior expected for a d-V high spin complex (SQUID measurements) with a triplet electronic ground state (ca.

Helicobacter pylori resistance to clarithromycin in Reunion Island.

Objective: The increasing resistance of Helicobacter pylori to clarithromycin led to developing new eradication treatment regimens. The objective of our observational study was to determine the proportion of H. pylori strains resistant to clarithromycin in infected patients in Reunion Island and to suggest a first-line treatment in agreement with the local ecology.