Charles Gerhardt Institute

Montpellier, France

Charles Gerhardt Institute

Montpellier, France
SEARCH FILTERS
Time filter
Source Type

Croissant J.,University of California at Los Angeles | Croissant J.,Charles Gerhardt Institute | Zink J.I.,University of California at Los Angeles
Journal of the American Chemical Society | Year: 2012

The synthesis and operation of a light-operated nanovalve that controls the pore openings of mesoporous silica nanoparticles containing gold nanoparticle cores is described. The nanoparticles, consisting of 20 nm gold cores inside ∼150 nm mesoporous silica spheres, were synthesized using a unique one-pot method. The nanovalves consist of cucurbit[6]uril rings encircling stalks that are attached to the ∼2 nm pore openings. Plasmonic heating of the gold core raises the local temperature and decreases the ring-stalk binding constant, thereby unblocking the pore and releasing the cargo molecules that were preloaded inside. Bulk heating of the suspended particles to 60 °C is required to release the cargo, but no bulk temperature change was observed in the plasmonic heating release experiment. High-intensity irradiation caused thermal damage to the silica particles, but low-intensity illumination caused a local temperature increase sufficient to operate the valves without damaging the nanoparticle containers. These light-stimulated, thermally activated, mechanized nanoparticles represent a new system with potential utility for on-command drug release. © 2012 American Chemical Society.


Zaggia A.,University of Padua | Ameduri B.,Charles Gerhardt Institute
Current Opinion in Colloid and Interface Science | Year: 2012

Fluorinated surfactants are exceptional compounds that have found many applications in everyday life. This review focuses on severe issues on the toxicity, persistency and bioaccumulation of these halogenated products, especially perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), the half-lives of which are several years in human serum. After an introduction on their productions, uses and hazards, this minireview updates non-exhaustive recent strategies of synthesis of original fluorosurfactants that may be potentially non-bioaccumulable. These routes have been devoted on: (i) the preparation of CF 3-X-(CH 2) n-SO 3Na (with X=O, C 6H 4O or N(CF 3) and n=8-12), (ii) the use of fluorinated polyethers (achieved either by oligomerization of hexafluoropropylene oxide (HFPO) or by ring opening cationic oligomerization of fluorinated oxetanes; (iii) the telomerization of vinylidene fluoride (VDF) with 1-iodoperfluoralkanes to produce C nF 2n+1-(VDF) 2-CH 2CO 2R (n=2 or 4, R=H or NH 4), (iv) the radical telomerization of 3,3,3-trifluoropropene (TFP) with isoperfluoropropyliodide to prepare (CF 3) 2CF(TFP) x-R H, and (v) the radical cotelomerization of VDF and TFP, or their controlled radical copolymerization in the presence of either (CF 3) 2CFI or a fluorinated xanthate. In most cases, the surface tensions versus the surfactant concentrations have been assessed. These above pathways led to various highly fluorinated (but yet not perfluorinated) telomers or cooligomers, the chemical changes of which enabled to obtain original surfactants as novel alternatives to PFOA, ammonium perfluorooctanoate (APFO), or PFOS regarded as the PCBs of the XXIst century. © 2012 Elsevier Ltd.


Le Bideau J.,University of Nantes | Viau L.,Charles Gerhardt Institute | Vioux A.,Charles Gerhardt Institute
Chemical Society Reviews | Year: 2011

The current interest in ionic liquids (ILs) is motivated by some unique properties, such as negligible vapour pressure, thermal stability and non-flammability, combined with high ionic conductivity and wide electrochemical stability window. However, for material applications, there is a challenging need for immobilizing ILs in solid devices, while keeping their specific properties. In this critical review, ionogels are presented as a new class of hybrid materials, in which the properties of the IL are hybridized with those of another component, which may be organic (low molecular weight gelator, (bio)polymer), inorganic (e.g. carbon nanotubes, silica etc.) or hybrid organic-inorganic (e.g. polymer and inorganic fillers). Actually, ILs act as structuring media during the formation of inorganic ionogels, their intrinsic organization and physicochemical properties influencing the building of the solid host network. Conversely, some effects of confinement can modify some properties of the guest IL, even though liquid-like dynamics and ion mobility are preserved. Ionogels, which keep the main properties of ILs except outflow, while allowing easy shaping, considerably enlarge the array of applications of ILs. Thus, they form a promising family of solid electrolyte membranes, which gives access to all-solid devices, a topical industrial challenge in domains such as lithium batteries, fuel cells and dye-sensitized solar cells. Replacing conventional media, organic solvents in lithium batteries or water in proton-exchange-membrane fuel cells (PEMFC), by low-vapour-pressure and non flammable ILs presents major advantages such as improved safety and a higher operating temperature range. Implementation of ILs in separation techniques, where they benefit from huge advantages as well, relies again on the development of supported IL membranes such as ionogels. Moreover, functionalization of ionogels can be achieved both by incorporation of organic functions in the solid matrix, and by encapsulation of molecular species (from metal complexes to enzymes) in the immobilized IL phase, which opens new routes for designing advanced materials, especially (bio)catalytic membranes, sensors and drug release systems (194 references). © 2011 The Royal Society of Chemistry.


Morozan A.,Charles Gerhardt Institute | Jaouen F.,Charles Gerhardt Institute
Energy and Environmental Science | Year: 2012

Metal-organic frameworks (MOFs) have received huge attention in the last years as promising porous materials with unrivalled degree of tunability for a wide range of applications including gas storage or separation, catalysis, drug delivery and imaging. The present review appraises the application of MOFs in the field of electrochemistry. From materials for rechargeable batteries, supercapacitors and fuel cells to electrocatalysis or corrosion inhibition, MOFs or MOF-derived materials are gaining momentum in this field. For real breakthroughs, combining their electrochemical properties with appropriate electronic and ionic conductivity will be required. © 2012 The Royal Society of Chemistry.


Mehdi A.,Charles Gerhardt Institute | Reye C.,Charles Gerhardt Institute | Corriu R.,Charles Gerhardt Institute
Chemical Society Reviews | Year: 2011

This tutorial review reports upon the organisation and functionalization of two families of hybrid organic-inorganic materials. We attempted to show in both cases the best ways permitting the organisation of materials in terms of properties at the nanometric scale. The first family concerns mesoporous hybrid organic-inorganic materials prepared in the presence of a structure-directing agent. We describe the functionalization of the channel pores of ordered mesoporous silica, that of the silica framework, as well as the functionalization of both of them simultaneously. This family is currently one of the best supports for exploring polyfunctional materials, which can provide a route to interactive materials. The second family concerns lamellar hybrid organic-inorganic materials which is a new class of nanostructured materials. These materials were first obtained by self-assembly, as a result of van der Waals interactions of bridged organosilica precursors containing long alkylene chains during the sol-gel process, without any structure directing agent. This methodology has been extended to functional materials. It is also shown that such materials can be obtained from monosilylated precursors. © 2011 The Royal Society of Chemistry.


deRichter R.,Charles Gerhardt Institute | Caillol S.,Charles Gerhardt Institute
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2011

At the laboratory scale, photocatalysis is a promising method to convert many air pollutants such as nitrogen oxides and volatile organic compounds, to safer products for human health but also environmentally more acceptable, such as nitrate and carbon dioxide.Indoor and industrial applications of photocatalysis to remove local air pollutants from the atmosphere are now numerous. Large scale outdoor applications of photocatalysis started with self-cleaning glass, coatings and paints for buildings, and several outdoor experiments have been documented regarding the photocatalytic reduction of NOx levels in urban environment, such as tunnels, streets and highways.The potential applications of photocatalysis, to remove or mitigate a wide range of global warming contributors from the atmosphere, seem an attractive method to help fighting climate change. By harnessing solar energy, photocatalytic processes consume less energy than conventional methods. This review article shows that photocatalysis may be applied successfully to eliminate or transform of all major long-lived well mixed greenhouse gases, but also soot and tropospheric ozone and other short-lived climate forcers. The cases of sulphur hexafluoride and nitrogen trifluoride are also discussed. © 2011 Elsevier B.V.


Debecker D.P.,Catholic University of Louvain | Mutin P.H.,Charles Gerhardt Institute
Chemical Society Reviews | Year: 2012

Oxides and mixed oxides have a tremendous importance in the field of heterogeneous catalysis, serving either as catalysts or as supports for active species. The performance of a catalyst depends directly on its composition, texture, structure and surface properties, which have to be precisely controlled and adapted to each application. In this context, the sol-gel process is a unique tool for the preparation and understanding of catalytic materials, owing to its exceptional versatility. In the last 10 years, the non-hydrolytic sol-gel (NHSG) or non-aqueous sol-gel process based on nonhydrolytic condensations in nonaqueous media has established itself as a simple and powerful method for the design of a wide range of oxide, mixed oxide and hybrid materials with controlled composition, morphology, texture and structure. NHSG proved particularly interesting for the preparation of catalytic materials, notably mesoporous xerogels, single site catalysts and highly crystalline nanoparticles. This critical review addresses the application of NHSG to the preparation of heterogeneous catalysts, emphasizing the specificities of this process, and giving a comprehensive overview of the literature (251 references). © The Royal Society of Chemistry 2012.


Alonso B.,Charles Gerhardt Institute | Marichal C.,CNRS Mulhouse Institute of Materials Science
Chemical Society Reviews | Year: 2013

In this tutorial review we intend to give an overview of the potential of NMR spectroscopy, and in particular solid-state NMR, in characterising micelle-templated mesoporous materials. Different topics are covered including the study of formation mechanisms, the characterisation of structures, textures, surfaces and interfaces, functionalisation, dynamic properties and structure-reactivity correlations. Some selected examples illustrate the variety of information provided by this spectroscopy. Particular attention is paid to recent technological and/or methodological developments. © The Royal Society of Chemistry 2013.


Diaz U.,Polytechnic University of Valencia | Brunel D.,Polytechnic University of Valencia | Brunel D.,Charles Gerhardt Institute | Corma A.,Polytechnic University of Valencia
Chemical Society Reviews | Year: 2013

Organic-inorganic hybrid materials with different levels of structuration and porous hierarchy and one or several types of active sites in the framework can catalyze multistep chemical processes in a one-pot reactor system following a cascade of reaction events. It will show how the different active sites can act in a synergistic or in a consecutive way following a similar functionality model to biological multisite catalysts. Research on this subject for heterogeneous catalysts is still in the beginning stage and very interesting results can be expected if we are able to successfully combine the properties of organic and inorganic catalysts. © The Royal Society of Chemistry 2013.


Mehdi A.,Charles Gerhardt Institute
Journal of Materials Chemistry | Year: 2010

This paper is devoted to layered hybrid organic-inorganic materials obtained by self-assembly of organosilica precursors during the hydrolytic sol-gel process. The self-assembly is induced by lipophilic van der Waals interactions between alkylene chains. The introduction of functional groups such as -SS- gives rise to -SH or -SO 3H functionalized materials after chemical modifications. This methodology has been extended to the formation of lamellar hybrid materials containing amino groups thanks to CO 2 as bridging groups as well as the formation of lamellar hybrid materials containing carboxylic groups. In this last case, the material was elaborated thanks to in situ hydrogen bond formation between carboxylic acid groups. An easy preparation of bis-zwitterionic lamellar material from only 3-aminopropyltriethoxysilane, succinic anhydride, and ethylene diamine will be also presented. All these functional materials exhibit a very high chelating capability towards transition metal and lanthanide ions and can be used for environmental remediation. © 2010 The Royal Society of Chemistry.

Loading Charles Gerhardt Institute collaborators
Loading Charles Gerhardt Institute collaborators