Proton conductivity versus acidic strength of one-pot synthesized acidic functionalized SBA-15 Mesoporous silica

International audienceThis paper reports the one-pot synthesis and characterization of functionalized mesoporous SBA-15 silica, containing two loadings of different acid groups (-CO2H, -PO(OH)2 and -SO3H). The thermodynamic features of the water confined in these porous silicas is investigated by Differential Scanning Calorimetry (DSC). The results show that the melting behaviour of the confined water is mainly governed by the pore diameter and, as a consequence, indicate that the chemical "decoration" of the porous surface does not play any key role on water thermodynamics in that case. On the contrary, the proton conductivity of the hydrated mesoporous materials, examined in a wide range of temperatures (-100 to 70°C), turns out to be strongly dependent on both the physical state of the confined water and the acidity of the functions located at the porous surface. The proton conductivity is shown to be directly related to the pKa and the density of the functional groups attached to the mesopore surface. The high conductivity values obtained at low temperature when the confined water is frozen, let us think that the -SO3H functionalized SBA-15 investigated here could be promising candidates for electrolyte solids applications in fuel cells

A Facile Strategy for In Situ Core-Template-Functionalizing Siliceous Hollow Nanospheres for Guest Species Entrapment

The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures

Structuration et fonctionnalisation de matériaux hybrides organiques-inorganiques

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Validation clinique d'une nouvelle approche "ISET" du diagnostic prénatal non invasif d'Amyotrophie spinale

Notre équipe a développé ISET (Isolation by Size of Epithelial Tumor/Trophoblastic cells), une approche prometteuse et non invasive pour le diagnostic prénatal de SMA. L'étude de validation clinique de la méthode ISET pour le DPN de SMA est réalisée suivant le protocole défini par les statisticiens et méthodologistes du site Necker. L'approche, réalisée complètement en aveugle par rapport à la méthode invasive réalisée parallèlement, a visé 160 diagnostics génétiques de SMA par l'étude de 160 cellules foetales isolées du sang (20 ml, 10-11ème semaine d'aménorrhée) de 16 mères à risque (1/4) d'avoir un enfant atteint de la maladie. Les résultats valident la méthode ISET pour le diagnostic prénatal de SMA et constituent le premier cas de validation complète d'une méthode complètement non invasive de diagnostic prénatal de maladie génétique.A promising non-invasive strategy for prenatal diagnosis of SMA has been proposed using ISET (Isolation by Size of Epithelial Trophoblastic cells). A prospective blinded clinical validation study of the ISET method for SMA was set up in the Necker-Enfants Malades Hospital in Paris according to statistical recommendations. It targeted 160 genetic diagnoses of SMA through the study of 160 fetal cells obtained from the blood (20 ml) of 16 mothers at risk of having an affected child. The results show the successful validation of the ISET method for prenatal diagnosis of SMA and should have implications for the implementation of a safe prenatal diagnosis of this genetic disease in clinical practice.PARIS5-BU Méd.Cochin (751142101) / SudocSudocFranceF

Synthesis of bifunctionalized-pore mesoporous organosilica. Study of the accessibility and the distribution of functions in the pore channels

International audienceIn this paper, we report the synthesis in one step of ordered (hexagonal phase) mesoporous silicas functionalized with two different organic groups [HS(CH2)3– and acac(CH2)3–] located in the pore channels. These materials were characterized by X-ray diffraction measurements, transmission electron spectroscopy, nitrogen adsorption analyses and solid state 13C and 29Si NMR spectroscopies. The bifunctionalization of the internal pore's surface by the organic groups was clearly evidenced by elemental analyses and chemical reactivity. In addition, we have shown that the organic groups were regularly distributed on the pore's surface

From simple molecules to highly functionalised lamellar materials

We describe here a new method permitting the one-step synthesis of ordered (lamellar phase) organosilicas highly functionalised with carboxylic acid or phosphonic acid groups. These materials were obtained by hydrolysis and polycondensation of monosilylated precursors cyanoalkyltrialkoxysilane (NC-(CH2)nSi(OR)3) and diethylphosphonatoalkyltriethoxysilane ((EtO)2(O)P-(CH2)nSi(OEt)3) in acidic media without any structure-directing agent. The hydrolysis of -CN and -P(O)(OEt)2 groups into -COOH and -P(O)(OH)2 involves the in situ formation of dimers by strong hydrogen bonds, which is the crucial step to obtain a solid. The involvement of hydrophobic interactions between alkylene chains was also evidenced. All materials were characterised by X-ray diffraction measurements, elemental analyses and solid-state 13 C and 29 Si NMR spectroscopies. The accessibility and adsorption capacity of these groups towards lanthanide ions were investigate

Bifunctional ordered mesoporous materials: direct synthesis and study of the distribution of two distinct functional groups in the pore channels

International audienceIn this paper, we report the study of the distribution (regular or irregular distribution or segregation) of two distinct functional groups located within the pore channels of ordered mesoporous organosilicas. For that purpose, we have chosen two probes, both of them depending on the proximity of two organic groups. One was based on the chelating property towards EuCl3 of acetyl acetonate (acac) and carboxylate groups. The other concerns the ion-exchange capability of the sulfonic acid moieties, which depends on the proximity of the acid groups. In the first part, various ordered monofunctional mesoporous organosilicas were prepared by co-condensation of tetraethylorthosilicate (TEOS) and an organotriethoxysilane –(CH2)3–Si(OEt)3 (with = acetylacetonate (acac), CN, SH, Cl, NH2 and H) in the presence of the triblock copolymer P123 as a structure-directing agent at pH = 1.5. Thanks to the probes, we have first showed that all the organic groups (SH, CN, acac) are accessible and regularly distributed within the channel pores of monofunctional mesoporous materials. In the second part, several ordered mesoporous materials containing two distinct functional groups including at least one probe were prepared in one step by co-condensation of TEOS and two organotriethoxysilanes –(CH2)3–Si(OEt)3 and –(CH2)3–Si(OEt)3, under the same experimental conditions as previously. Taking into account the results obtained with the monofunctional materials as references, the distribution of two distinct functional groups located on the pores surfaces of mesoporous materials was determined and discusse

Synthesis of new lamellar materials by self-assembly and coordination chemistry in the solids

International audienceWe report the preparation of a new class of lamellar hybrid organic–inorganic materials obtained by self-assembly of bridged organosilica precursors containing long alkylene chains during the sol–gel process. The self- assembly is induced by lipophilic van derWaals interactions. The introduction of –SS– bonds in the core of the alkylene chains permitted the functionalisation of lamellar materials, which were subsequently transformed into SH and –SO3H groups. This methodology was extended to the formation of lamellar hybridmaterials containing amino groups thanks to CO2 as bridging groups as well as the formation of lamellar hybrid materials containing carboxylic groups. In this last case, the hydrolysis and polycondensation of cyanoalkyl- trialkoxysilanes permitted the one pot synthesis of lamellar hybrid materials thanks to in situ hydrogen bonds formation between carboxylic acids groups. All these functional lamellar materials exhibit a very high chelating capability towards transition metal and lanthanide ions

Influence of the location of Rh(0) particles within MCM-41 materials on the selectivity of hydrogenation reactions

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Metathetic degradation of natural rubber in ionic liquids: a new way to telechelic polyisoprene

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