Mesoporous organic-inorganic hybrid materials, a new class of materials characterized by large specific surface areas and pore sizes between 2 and 15 nm, have been obtained through the coupling of inorganic and organic components by template synthesis. The incorporation of functionalities can be achieved in three ways: by subsequent attachment of organic components onto a pure silica matrix (grafting), by simultaneous reaction of condensable inorganic silica species and silylated organic compounds (co-condensation, one-pot synthesis), and by the use of bissilylated organic precursors that lead to periodic mesoporous organosilicas (PMOs). This Review gives an overview of the preparation, properties, and potential applications of these materials in the areas of catalysis, sorption, chromatography, and the construction of systems for controlled release of active compounds, as well as molecular switches, with the main focus being on PMOs.

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Hexagonal mesoporous titanosilicates with distinguishable framework charges and textural mesoporosity, namely, Ti-MCM-41 and Ti-HMS, were prepared at ambient temperature by electrostatic and neutral assembly processes, respectively. Titanium incorporation at the 2 mol % level for both materials was accompanied by increases in lattice parameters and wall thicknesses, but the framework pore sizes remained unaffected. Cross-linking of the anionic framework of as-synthesized Ti-substituted MCM-41 prepared by electrostatic S+I- and S+X-I+ assembly pathways (where S+ is a quaternary ammonium surfactant and I- and I+ are ionic silicon precursors) was enhanced significantly by Ti substitution, as judged by 29Si MAS NMR. The neutral framework of as-synthesized Ti-HMS formed by S°I° assembly (where S° is a primary amine and I° is a neutral silicon precursor) exhibited the same high degree of cross-linking as the unsubstituted silica analog. UV−vis and XANES spectra for the calcined forms of Ti-MCM-41 and Ti-HMS indicated (i) the presence of site-isolated Ti species in the framework, (ii) predominantly tetrahedral coordination for Ti, along with some rehydrated five- and six-coordinated sites, and (iii) Ti siting that was virtually independent of the framework assembly pathway. All mesoporous molecular sieves exhibited catalytic activities superior to that of titanium silicalite for the liquid phase peroxide oxidations of methyl methacrylate, styrene, and 2, 6-di-tert-butylphenol. The exceptional catalytic activity in the case of Ti-HMS, especially toward larger substrates, was attributable to the small crystallite size and complementary textural mesoporosity that facilitates substrate access to framework Ti sites.

Periodic mesoporous organosilicas (PMOs) with unusually large pores and high BET surface areas have been synthesized using triblock PEO-PPO-PEO copolymer P123 as the structure-directing agent and 1,2-bis(trimethoxysilyl)ethane (BTME) as the organically bridged silica source.

Mesoporous organic-inorganic hybrid materials are an interesting class of materials, which combine the advantages of two worlds; the inorganic part builds a robust substrate while organic functions make them alive in a way that they can be potentially used in a number of applications. In this tutorial review, we provide an overview of how mesoporous materials are synthesised via the 'soft template' path and how the incorporation of organic functions can be achieved. Furthermore, a colourful survey full of examples is presented, providing a small overview of field of applications that can potentially benefit from the use of periodic mesoporous organosilicas (PMOs) and related materials.

The extraction of water from air is a promising way to supply fresh water, especially in remote, arid regions. This process can be supported by desiccant materials such as zeolites, metal−organic frameworks, or hygroscopic salts. Here we present a composite material that is able to absorb 660 kg of water per cubic meter of bulk material from air at 10 mbar water vapor pressure and 28°C. The material consists of calcium chloride incorporated into an alginate-derived matrix. A simple synthesis route leads to spherical beads of the composite with a diameter of approximately 2 mm. This macroscopic structure allows for good vapor permeability through packed beds. The collected water can be released at 100°C, potentially enabling a solar-driven application. In addition, the synthetic route uses cheap, non-toxic, and easily accessible materials allowing for widespread application.

Ordered mesoporous CMK carbons and periodic mesoporous organosilica (PMO) materials have been characterized by combining nitrogen (77.4 K) and argon (87.3 K) adsorption with recently developed quenched solid density functional theory (QSDFT). Systematic, high-resolution water adsorption experiments have been performed in the temperature range from 298 to 318 K in order to ascertain the effect of surface chemistry (using periodic mesoporous organosilicas (PMOs) of given pore size) and pore size/pore geometry (using CMK-3, CMK-8 carbons) on the adsorption, pore filling, condensation and hysteresis behavior. These data reveal how the interplay between confined geometry effects and the strength of the adsorption forces influence the adsorption, wetting, and phase behavior of pore fluids. Further, our results indicate that water adsorption is quite sensitive to both small changes in pore structure and surface chemistry, showing the potential of water adsorption as a powerful complementary tool for the characterization of nanoporous solids.

The syntheses and characterization of mesostructured hexagonally ordered surfactant composites using zirconium sulfate ions as inorganic precursor species are described. On the basis of the mesostructured zirconium sulfate surfactant composites, two porous MCM-41 analogues have been synthesized:  zirconium oxide−sulfate and zirconium oxo phosphate. For the zirconium oxo phosphates, a special postsynthetic treatment has been developed. The pore arrangements and wall structures were characterized by XRD, nitrogen adsorption, EXAFS, and TEM. The porous zirconia based materials show hexagonal arrangements of uniformly sized pores and amorphous pore walls. Both zirconium oxide−sulfate and zirconium oxo phosphate show remarkable thermal stability up to 500 °C. Therefore, the surfactant has been completely removed from the structures by calcination. So far, this is the highest thermal stability compared to other porous transition metal oxides prepared via surfactant-controlled synthesis.