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A new type of acidic macrocellular and mesoporous silica–alumina foam is obtained via a one pot alkaline sol–gel route coupled with a concentrated emulsion-based templating technique. The mixed oxide monolith exhibits high surface acidity, translating into excellent performance in the acid-catalyzed dehydration of bioethanol to ethene. [ABSTRACT FROM AUTHOR]

Aerosol-generated mesoporous organosilica submicronic spheres have been converted into porous silicon oxycarbide (SiCO) glasses by pyrolysis at 1000 °C in an inert atmosphere. Spherical mesoporous particles obtained from acidic solutions of 1,2-bis(triethoxysilyl) ethane and Pluronic® F127 structuring agent were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption/desorption, and multi nuclear solid-state magic-angle spinning (MAS) NMR. These particles were then pyrolyzed at 1000 °C and transformed into a SiCO phase as evidenced by 29Si MAS NMR, while TEM shows preserved mesoporosity, unfortunately difficult to access owing to the presence of an outer layer of dense silica. [ABSTRACT FROM AUTHOR]

A novel technique combining inkjet printing (IJP), evaporation-inducedself-assembly (EISA), and click chemistry is implemented for elaboratingmesoporous silica-based multifunctional microdots arrays. The microdotsare in situ azide-functionalized with (3-azidopropyl)triethoxysilane(AzPTES). AzPTES is directly added to the initial sol before IJP andco-condenses with the silica precursor (TEOS) during the evaporation-inducedself-assembly (EISA) of micelles on the substrate. After extractingthe surfactants to release the porosity, model alkynes, namely propargylalcohol, methyl pent-4-ynoate, ethynylferrocene, and N-propargyl-4-amino-1,8-naphthalimide, are grafted by the azide–alkyneCuAAC click reaction. The demonstration is established that the clickreaction is nearly quantitative and occurs in the whole volume ofthe microdots attesting the accessibility of the azide groups. Byintegrating an alkyne-containing silylated precursor in a similarroute, azide-containing functional groups are anchored in the microdotsby click reaction. A demonstration of the multifunctionalization ofsuch microdots arrays is achieved by reacting clickable dyes on alternatealkyne- and azide-functionalized lines of microdots, as evidencedby confocal fluorescence microscopy. Such multifunctional mesoporoussilica microdots arrays offer promising perspectives for biosensingapplications. [ABSTRACT FROM AUTHOR]

A comparative study of the degradation in a model phosphatebufferedsaline (PBS) medium of mesoporous mixed silica–zirconia oxidesand hybrid organosilica materials is reported, and their thermodynamicand kinetic stability are discussed. Thin film morphology was usedto monitor the degradation rates of all these materials for the firsttime directly in liquid and undersaturated medium. The introductionof zirconium centers in mesoporous materials strongly inhibits degradationand allowed the self-limitation of soluble silica concentration inthe immediate environment of the vector. This avoids renucleationof potentially toxic silica small nanoparticles with uncontrolledsurface chemistry in the release medium. Chemical modifications (hybridationor zirconia doping) of mesoporous silica allow the fine-tuning ofits degradation from hours to days. Methylated thin films are highlystable when the functionalization ratio is high (50%). The hybridationby mercaptopropyl and aminopropyl moieties can be successfully performedwithout any high thermal treatment, allowing not only slowing downsilica dissolution but also opening the possibility to introduce inone-pot other thermally fragile molecules into the vector. Dissolutionrates K measured for the first time at different biologically relevanttemperatures follows an Arrhenius law: K= KoExp(−Ea/RT). Stabilities of these chemically modified silicas aremainly associated with a strong decrease of the pre-exponential factor K0of modified silicas. Counterintuitively, activationenergies Eadecrease with increasing thehybrid/silica or the zirconia/silica ratios. [ABSTRACT FROM AUTHOR]

Abstract: Solid-state NMR methods based on dipolar and J-derived experiments such as CP, MAS-J-HMQC and MAS-J-INEPT MAS have been developed in the frame of the {31P,29Si} spin pair. The potential of these techniques has been demonstrated using model compounds including crystalline silicophosphate phases (Si5O(PO4)6 and various SiP2O7 polymorphs). Spatial interactions as well as through-bond connectivities were established. Evaluation of isotropic 2 J P–O–Si coupling constants has been established by careful analysis of the HMQC and INEPT build-up curves under fast MAS. The efficiency of the 31P→ 29Si CP MAS experiment for the detailed characterization of Si–O–P mesoporous materials (at low temperature) was demonstrated. The incorporation of P atoms in the silica network has been proved unambiguously. Such materials could be appropriate for biocompatibility purposes. [Copyright &y& Elsevier]