Periodic mesoporous materials offer unique environments for chemical reactions and for the stabilization of unusual nanostructures.The discovery of the M41S family of mesoporous silica by Beck and co-workers in 1992 [1] has led to the rapid development of a wide variety of periodic mesoporous silicates and other materials that exhibit long range order based on cooperative self-assembly of surfactants with framework building blocks [2,3].Periodic mesoporous materials can be assembled from ionic or non-ionic surfactants interacting with framework building blocks such as silicate ions in aqueous solution.Under conditions that are conducive to condensation reactions of the framework building blocks,periodic structures with channels and pores at the order of about 2-20 nm can be created.These materials are particularly attractive due to their large channel diameters,enormous surface areas,the ability to tune pore sizes and -topologies,and almost endless opportunities regarding molecular modification and host-guest chemistry in their pore systems.Access to the pores is achieved by calcination of the materials or via extraction of the organic surfactants from the framework. These materials are expected to play an important role in the design of new hybrid catalysts and absorbers,in the immobilisation of enzymes and other biomolecules,as hosts for nanoparticle and nanowire synthesis,and as ultrafiltration membranes and chemical sensors.
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