The thermodynamics and conductivity of water confined in nanoporous silicas SBA-15 are studied using differential scanning calorimetry and impedance spectroscopy. The effect of the water/surface interaction is addressed by investigating samples with different surface chemistries.

A mesoporous hybrid material containing free phosphine oxide ligands in the pore walls was prepared in the presence of a structure-directing agent. The phosphine oxide ligands were proved to operate as templates for further erbium(m) and/or ytterbium(III) ion complexation.

Electron paramagnetic resonance (EPR) experiments were performed on mesoporous silica powders in which (1,4,8,11-tetraazacyclotetradecane) cyclam groups were incorporated. These functionalised groups allow an easy binding with copper and nickel ions. Comparative studies are carried out on samples functionalised by cyclam groups located either inside the pores or in the walls of the mesoporous structures. Copper and nickel EPR parameters, including g-tensors and hyperfine components are determined and relevant electronic, magnetic and structural information are obtained. The EPR spectra intensities and line-widths are investigated on the temperature range [4K,300K] to clarify the relative dispersion or agglomeration of the doping ions in the matrices as well as their possible thermally activated mobility and ions pairing. As a support of the experimental EPR investigations, numerical simulations of the geometry of metallic ion environments and their electronic properties are carried out and discussed. The possibility of dynamic Jahn Teller (JT) effect in the temperature range [200, 60K] is discussed for the nickel doped matrices where the low temperature quenched JT configuration is thought to favour the formation of Ni3+ pairs.

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. We showed that whatever the proportion in organic groups, only 2D hexagonal phase having p6m symmetry was observed for all the materials indicating a good compatibility between the organic groups. The bi-functionalization of the internal pores surface by the organotriethoxysilanes groups was clearly evidenced by using micro-Raman spectroscopy.

A key parameter for the choice of an erbium-doped material suitable for efficient amplification around 1.55 μm is its ability to isolate Er ions from each other in order to increase the quenching concentration and henceforth to improve pumping efficiency. Encapsulation of Er ions by organic ligands results in quenching concentrations about a few % in a polymer matrix and may therefore induce high gain values at 1.55 μm. In this paper, we report on the elaboration and optical characterization of Erbium complex-doped PMMA thin films and waveguides with different concentrations by spin-coating technique. Refractive index of these thin films and etching conditions for waveguide fabrication are carefully investigated. Strong gain coefficient values (up to 9 cm-1) measured by Amplified Spontaneous Emission are reported at 1.55 μm under 980 nm cw pumping of an erbium-complex-doped PMMA film. A multifunctional polymer material containing an erbium complex together with an electric-field oriented nonlinear optical (NLO) chromophore is shown to simultaneously display good IR gain properties and quadratic NLO response, then qualifying this approach for in-situ amplification of active electro-optic devices for optical signal processing. Rib waveguides made of erbium-doped PMMA have been elaborated using standard lithographic and reactive ionic etching techniques. Gain and loss measurements of these waveguides are characterized for single mode propagation of signal (1.55 μm) and pump (980 nm) waves, and compared to predictions from beam propagation method modelization.

Ordered mesoporous silicas with large-pore diameters incorporating aminopropyl groups in variable quantity have been synthesized via the co-condensation of tetraethyl orthosilicate (TEOS) and 3-tertbutyloxycarbonylaminopropyltriethoxysilane templated with nonionic surfactant P123 under acidic conditions. The deprotection of amino groups was then quantitatively achieved either by thermal treatment or acid hydrolysis followed by Et3N treatment, both routes leading to exactly the same materials. We showed that the free amino centers are fully accessible, by using the condensation of the amine function with benzaldehyde.

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.

This paper describes the synthesis of 4,4'-[(triisopropoxysilyl)propyloxy]azobenzene and the preparation of the ordered hybrid material containing the bridged azobenzene moieties within the framework by using the direct liquid crystal templating approach. We show that a sizable fraction of the azobenzene groups is reversibly photoisomerized though the chromophore is covalently linked to the silica matrix at both ends. In contrast, the photoisomerization did not occur in the corresponding material prepared in the absence of template. This is explained by a regular dilution of the chromophores into silica thanks to the template used for the preparation of the material.

Direct syntheses of silicas containing organoflrinated groups have been achieved by co-condensation of tetraethylorthosilicate (TEOS) and a organoflrinated triethoxysilane, R-F(CH2)(2)Si(OEt)(3)[R-F = CF3(CF2)(5) or CF3], in the presence of either the neutral fluorinated surfactant n-CF3(CF2)(7)(CH2)(2)NH2 or the cationic one, n-CF3(CF2)(7)(CH2)(2)NMe3+I-. Microporous silica with a wormhole structure containing the C-8 fluorinated chain was obtained in the presence of the nonionic surfactant. It was shown that the use of fluorinated surfactants allows the incorporation of an amount of (fluorinated) chains located in the channel pores that is superior to that obtained by using a hydrogenated surfactant. The cationic surfactant used under acidic conditions allowed the incorporation of only a low amount of the C-8 fluorinated chain, leading to a poorly structured material. In contrast, a mesoporous silica containing the CF3(CH2)(2) group and showing a hexagonal arrangement was obtained under the same experimental conditions.

For the first time, hybrid materials with long-range order (lamellar and even 2D hexagonal) were obtained during hydrolysis–polycondensation of α,ω-bis(trimethoxysilyl)alkanes thanks to hydrophobic van-der-Waals type interactions using highly hydrophilic conditions, the nanostructure depending mainly on the alkylene chain lengths.

This article is focused on mesoporous hybrid organic–inorganic materials prepared in the presence of structure-directing agents. We attempt to show that they are currently the best supports for exploring polyfunctional materials, which can provide a route to interactive materials. We define interactive materials as nanomaterials of which two properties are in a position to interact with one another. For the purpose of constructing such materials, we describe the functionalization of the channel pores of ordered mesoporous silica, the silica framework and the functionalisation of both, either successively or simultaneously. This last route could allow the preparation of materials coupling two physical properties, located on the nanometric range—one in the channel pores and the other in the silica framework—which could present unexpected interactions. This approach requires a mastery of the chemistry for the preparation of the appropriate precursors as well as of the structure.

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.

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.

The synthesis of a bis-silylated 15-membered azatriolefinic macrocycle is described as well as its co-gelification with tetraethyl orthosilicate. The resulting material was treated with Pd(dba)2 affording an hybrid organic–inorganic material containing macrocyclic palladium(0) complex covalently bonded to the silica matrix. The activity of this material as catalyst or precatalyst in Suzuki cross-coupling and telomerization of butadiene with methanol and phenol is presented.

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.

This paper emphasizes the wide possibilities open to organometallic chemistry by the bottom-up approach for nanosciences. In this new field of research, organometallic chemistry and coordination chemistry are in position to play a very important role in the development of nanomaterials. At first, organometallic and coordination chemistries will be the mothers of plenty of nanotools, which are the elemental bricks of nanosciences. The nanomaterials are obtained from them either by inclusion in a matrix (Nanocomposites) or by grafting methods (grafted nanomaterials). However, the most exciting field of investigation are the nanostructured hybrid materials which permit to open new fields of investigation such as self-organization of organic moieties or the coordination chemistry in the solid. Some examples are given. Moreover, the organometallic chemistry performed on both the framework and the pores of the nanoporous solids obtained by sol-gel chemistry in the presence of structure directing agents is opening the way to smart materials. These materials will have the ability to couple interactively two different properties. (C) 2004 Published by Elsevier B.V.

A new approach to the synthesis and the organization of Mn3O4 (hausmannite) nanoparticles has been developed using the thermolysis of the magnetic cluster [Mn12O12(C2H5COO)16(H2O)3] linked to a SBA-15 mesoporous silica functionalized with –COOH groups. The obtained composites were studied by X-Ray diffraction (XRD), infrared spectroscopy (IR), nitrogen sorption (BET), transmission electron microscopy (TEM) and magnetic measurements. These measurements reveal the presence of uniformly sized pure Mn3O4 nanoparticles inside the silica matrix. The nanoparticle size is in good correlation with the pore size of the hybrid silica used. All the data demonstrate that the anchoring of the cluster in the silica plays a crucial role in the fabrication of the nanocomposites.

Ordered mesoporous silica containing 3-chloropropyl groups was prepared by a direct synthetic approach involving hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) and 3-chloropropyltrimethoxysilane in the presence of the triblock copolymer P123 as the structure-directing agent and under acidic conditions. Nucleophilic displacement of chloro groups by cyclam moieties (cyclam = 1,4,8,11-tetraazacyclotetradecane) was then achieved almost quantitatively. Subsequent treatment of solids containing different amounts of cyclam moieties with an ethanolic solution of europium (III) chloride gave rise to 1∶1 EuIII/cyclam complexes. The EXAFS studies have shown that EuIII adopts an octahedral geometry.