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Porous materials displaying tailor-made pore sizes and shapes are particularly interesting in a great variety of real and potential applications where molecular recognition is needed, such as shape-selective catalysis, molecular sieving, and selective adsorption.[1±4] Classically, apart from silica, materials most commonly used for catalysis and catalyst supports have been those based on high surface aluminas, owing to their thermal, chemical, and mechanical stability and their low cost.[5] Earlier aluminas with high surface areas (~500 m 2 /g) had been prepared using structure-directing agents. However, they were X-ray amorphous materials and their porosity was purely textural, characterized by wide pore size distributions.[5] More recently, the discovery by researchers at Mobil of the M41S family of mesoporous silicas synthesized by using micellar aggregates as templates, [6,7] has promoted considerable development in the synthesis of materials with uniform pores in the mesoporous range.[8±14] However, in the case of mesoporous aluminum oxide, the usual strategies used in the synthesis of mesoporous silica have not always yielded satisfactory results and only a few papers have reported on surfactant-assisted synthesis of mesoporous alumina. Davis and co-workers [15] have reported the preparation of aluminas with narrow pore size distributions by the use of anionic surfactants but their solids always have an approximately constant pore size (ca. 20 ) that cannot be tailored by changing the surfactant length. Conversely, Pinnavaia and co-workers [16,17] report the use of neutral polyethylene oxides as directing agents for the synthesis of mesoporous solids for which both the d spacing and the pore diameters increase as the surfactant size does. In both cases, the synthetic pathway is based on typical procedures originally used for mesoporous silicas: the variation of the micelle diameter is achieved by increasing the surfactant chain length and/or addition of hydrophobic organic molecules. However, the scarcity and diversity of the reported results suggest that there is still a long way to go to obtain real control of the synthetic procedures for the preparation of mesoporous aluminas.In this context, we show that self-assembling processes leading to the formation of mesoporous aluminas can be controlled by adequately balancing such processes and the hydrolysis and condensation reactions occurring at the inorganic phase. This method has allowed us to isolate for the first time mesoporous aluminum oxides using cationic surfactants and, what is more important, to tune their pore size by the sole adjustment of the molar ratio of the reactants.Thermally stable aluminas with different pore diameters, henceforth denoted as ICMUV-1, were synthesized using CTABr (cetyltrimethylammonium bromide) as surfactantdirecting agent in a water/TEA (triethanolamine) medium. A constant 2/1 Al/CTABr molar ratio was always used, and the pore size adjustment was achieved by changing the Al (or surfactant)/water/TEA molar ratio.A typica...

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The functionalization of mesostructured and/or mesoporous MCM‐41 related silicas is easily achieved by treatment under NH3 atmosphere at relatively low temperatures without structural collapse. Nitridation, which occurs through a single‐step solid‐state reaction, yields for the first time ordered mesoporous silicon oxynitrides with high surface area (see Figure).

Silica-based MCM-41-like mesoporous materials with high cobalt content (∞ g Si/Co g 23) have been synthesized through a one-pot surfactant-assisted procedure from aqueous solution using a cationic surfactant (CTMABr ) cetyltrimethylammonium bromide) as structural directing agent, and starting from molecular atrane complexes of Co and Si as inorganic hydrolytic precursors. This preparative technique allows optimizing the dispersion of the Co guest species in the silica walls. The mesoporous nature of the final materials is confirmed by XRD, TEM, and N 2 adsorption-desorption isotherms. They display unimodal and relatively narrow pore size distributions, whereas their pore array evolves from ordered hexagonal (H 0 ) to wormhole-like (W) as the Co content increases. A careful spectroscopic (UV-visible and NMR) and magnetic study of these materials shows that, regardless of the Si/Co ratio, Co atoms are organized in well-dispersed, uniform CoO nanodomains (ca. 3 nm) partially embedded within the silica walls. These materials, which show superparamagnetic behavior, can be referred to as mesoporous CoO-MCM-41 nanocomposites.