New mesostructured organosilica with chiral sugar derived structures: nice host for gold nanoparticles stabilisation.

In this paper we describe the synthesis of functionalised mesoporous organosilicas containing a mannitol derivative in the framework. For this purpose, a bis-silylated precursor 3,4-Di-O-[3-(triethoxysilylpropyl)carbamate]-1,2:5,6-di-O-isopropylidene-D-mannitol was prepared by coupling of 1,2:5,6-di-O-isopropylidene-D-mannitol with 3-(triethoxysilylpropyl)isocyanate. The framework-functionalised materials were obtained in one step by the "direct synthesis" method which consists of a co-hydrolysis and polycondensation of a bis-silylated mannitol precursor with tetraethylorthosilicate (TEOS) in the presence of a non-ionic triblock co-polymer (P123) as structure-directing agent.

Self-assembly of layered organosilicas based on weak intermolecular interactions.

New layered hybrid organic-inorganic materials were obtained directly by hydrolysis and polycondensation of monosilylated precursors of type (EtO)(3)Si(CH(2))(3)NH(C=O)NHC(n)H(2n+1) (n = 3, 8, 12 and 16). These precursors were easily prepared by reaction between commercially available triethoxysilylpropylisocyanate and primary aminoalkanes. The obtained materials were characterized by combining elemental analysis, X-ray powder diffraction, (13)C, (29)Si NMR and FT-IR spectroscopies.

Selective lanthanides sequestration based on a self-assembled organosilica.

In this paper, we investigate the cation-exchange properties of a self-assembled hybrid material towards trivalent ions, lanthanides (La(3+), Eu(3+), Gd(3+), Yb(3+)) and Fe(3+). The bis-zwitterionic lamellar material was prepared by sol-gel process from only 3-aminopropyltriethoxysilane (APTES), succinic anhydride, and ethylenediamine. In ethanol heated under reflux, the exchange ethylenediammonium versus Ln(3+) proved to be complete by complexometry measurements and elemental analyses, one Cl(-) ion per one Ln(III) remaining as expected for charge balance.

Self-organization of porphyrin units induced by magnetic field during sol-gel polymerization.

The use of a magnetic field as a controlling factor during the hydrolysis-polycondensation of porphyrin precursors substituted by Si(OR)(3) groups, induces a self-organization of porphyrin moieties due to the stacking of these units in the hybrid material and this study also confirms the effect of the magnetic field in the nano- and micrometric organization during the kinetically controlled polycondensation process.

Exceptional affinity of nanostructured organic-inorganic hybrid materials towards dioxygen: confinement effect of copper complexes.

We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species.

Mesoporous materials with an acidic framework and basic pores. A successful cohabitation.

Bifunctional mesoporous material with an acidic framework and basic pores was synthesized via the co-condensation of TEOS, bistrimethoxysilylated precursors with a disulfide core, and 3-tert-butyloxycarbonyl (aminopropyl)triethoxysilane using P123 as surfactant; the reduction of disulfide units to SH groups followed by their oxidation into SO3H and deprotection of amino groups gave rise to a material containing two antagonist functionalities located at the nanometric scale in a successful cohabitation, avoiding their mutual destruction in the presence of aprotic solvent. This kind of material illustrates the large possibilities offered by mesoporous materials and opens new and unsuspected applications.

First direct synthesis of highly ordered bifunctionalized mesoporous silica thin films.

Optically transparent and highly ordered mesoporous organosilica thin films functionalized with two different organic groups in various proportions were synthesized by templated-directed cocondensation of tetraethylorthosilicate (TEOS) and a mixture of two distinct and functional organotriethoxysilanes [NC(CH2)3Si(OEt)3 and O=P(OEt)2(CH2)3Si(OEt)3]. The mesostructured films obtained by evaporation induced self-assembly (EISA) approach were deposited on glass or silicon substrates by dip-coating. They were characterized by Grazing Incidence Small Angle X-ray Scattering (GISAXS) and X-ray reflectivity.

An original synthesis of highly ordered organosilica with a high content of thiol groups.

Well ordered bridged organosilica highly functionalised with disulfide groups were obtained by self-assembly of alpha,omega-bis(trimethoxysilyl)alkyldisulfide under hydrophilic conditions; the reduction of disulfide cores to SH groups gave rise to material having a high mercury ion adsorption capacity.

CO2 as a supramolecular assembly agent: a route for lamellar materials with a high content of amine groups.

The uptake of carbon dioxide on N-(2-aminoethyl)-3-aminopropyltrimethoxysilane 1 and N-(6-aminohexyl)-3-aminopropyltrimethoxysilane 2 afforded a supramolecular network of bis-silylated ammonium carbamate salts, the hydrolytic polycondensation of which gave rise to structured hybrid materials. Subsequent loss of CO2 was readily achieved upon heating, thus generating materials in which the structure was maintained (well-defined lamellar structure from 2) and contains free amino groups. The accessibility of amine-functionalized groups was shown by their ability to complex transition metal or lanthanide salts.

One-step template-directed synthesis of multifunctionalised nanoporous silica: on the way to interactive nanomaterials.

The preparation of multifunctional mesoporous silica containing a NLO chromophore in the framework (bridged azobenzene phosphonium salts) and mercaptopropyl groups able to stabilize gold(0) nanoparticles in the channel pores was achieved in one step by using the direct liquid crystal templating approach.

Direct syntheses of functionalized mesostructured silica by using an inexpensive silica source.

The co-condensation of water soluble sodium silicate and different organotrialkoxysilanes in the presence of non-ionic triblock copolymers under acidic conditions provides a very convenient, general and economic one step synthesis methodology for the preparation of organically functionalised mesostructured silica.

Self-organization of a tetrasubstituted tetrathiafulvalene (TTF) in a silica based hybrid organic-inorganic material.

A hybrid organic inorganic nanostructured material containing a TTF core substituted by four arms exhibited a high level of both condensation at silicon (96%) and self-organization as evidenced by X-ray diffraction and an unprecedented birefringent behaviour.

Coordination chemistry in the solid: evidence for coordination modes within hybrid materials different from those in solution.

Two routes of incorporation of europium(III) salts into cyclam-containing hybrid materials have been explored, to elucidate the coordination mode of EuIII in cyclam-containing hybrid materials in a study of the arrangement of cyclam moieties during the solgel process. They were 1) complexation of europium salts by N-tetrasubstituted 1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives bearing four hydrolysable Si(OEt)3 groups, followed by hydrolysis and polycondensation of these complexes; and 2) hydrolysis and polycondensation of N-tetrasubstituted silylated cyclam derivatives, then incorporation of europium salts directly into the hybrid materials. The coordination mode of europium salts within solids is not the same as in solution.

Auto-organisation of hybrid organic-inorganic materials prepared by sol-gel process.

Silica-based hybrid organic-inorganic materials prepared by sol-gel chemistry exhibit chemical and physical properties revealing their anisotropic organisation. Besides the opportunities that this phenomenon opens for the preparation of new materials, it also provides arguments to the chemist looking for a better comprehension and control of the organisation of solids.

Hydrolysis/Polycondensation in the Solid State: Access to Crystalline Silica-Based Hybrid Materials.

Mild solid/gas or solid/liquid reactions can be used to prepare crystalline organosilicates, a class of silica-based hybrid materials, from the corresponding solid chlorosilanes. Hydrolysis and polycondensation in the solid state lead to the formation of the highly anisotropic organosilicates.

Ceramics and Nanostructures from Molecular Precursors.

The elaboration of solids from the molecular scale by a kinetically controlled methodology is one of the main challenges of molecular chemistry. In the long term, this should permit the design of solids with desired properties. Here, some examples are given which show a few methods that have been used for the preparation of solids from molecular precursors.

Nanostructured Silica-Based Organic-Inorganic Hybrid Materials-Evidence for Self-Organization of a Xerogel Prepared by Sol-Gel Polymerization.

A hydrolytic polycondensation reaction of a rigid, rodlike nonmesomorphous precursor leads to an isotropic sol and then an anisotropic birefringent xerogel (see scheme). Optical and X-ray structural analyses demonstrate a short-range order and the possibility of a crystalline order.

Characterization of the surface organization of nanostructured hybrid organic-inorganic materials by time-of-flight secondary ion mass spectrometry.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used to analyse the surface composition of organic-inorganic hybrid solids obtained by a sol-gel process. Gels of type O(1.5)Si-R-SiO(1.

A Boron-Bridged Tetrathiaporphyrinogen.

Lewis acid and Lewis base centers are simultaneously present in the boron-bridged thiophene-containing porphyrinogen 1 that has been synthesized in high yield. Its crystal structure reveals a nonplanar macrocycle; this and the colorless aspect suggest the absence of a delocalized π-electron system. R = NiPr .