Mesoporous nanospace

Ariga et al. (2007) in a excellent review present, in a well documented and elegant way, the flexibility of the synthesis and formulation methods for designing and developing the mesoporous nanospaces, if the fundamental principles of supramolecular and coordination chemistry are taken as the leading concept. It was revealed that the structural dimensions of mesoporous materials permit access by functional supermolecules, including coordination complexes, and control of their functionality can be achieved by variation of pore geometry. 

Alberti K, Petting F (1994) Zeolites as sensitive materials for dielectric gas sensors. Sens Actuators B Chem 21 39-50 Ariga K, Vinu A, Hill JP, Mori T (2007) Coordination chemistry and supramolecular chemistry in mesoporous nanospace. Coord Chem Rev 251 2562-2591... 

Ford DM Simanek EE Shantz DF, Engineering nanospaces Ordered mesoporous silicas as model substrates for building complex hybrid materials, Nanotechnology, 2005,16, S458-S475. 

The so-called template-based technique has been found to be particularly suitable for the synthesis of carbons whose porosity is not only uniform in size and shape, but also periodically ordered in some cases. In this approach, the porous carbon is prepared through infiltration of an organic precursor into the nanochannels of an appropriate inorganic material (the template), followed by carbonization and then liberation of the resultant carbon from the template. Different nanospaces in templates have been used to confine the carbon precursors. The first templates used included, e.g., silica gel or porous glass [84,85], layered clays such as montmorillonite ortaeniolite [86,87], or pillared clays [88-90]. Several detailed reviews on this topic have been published [75,91-95] that cover the areas of microporous and, especially, mesoporous solids. Here, some illustrative examples will he presented in some detail rather than reviewing systematically the literature. 

The diffusion of reactants and products in porous-material-based nanoreactor could be greatly affected by the surface properties, which in turn could influence the catalytic activity and even selectivity of a chemical reaction taking place in the confined nanospace. Generally, organic molecules are hydrophobic and the silica-based mesoporous nanopores are hydrophihc. The difficulty in the diffusion of reactants and products in hydrophobic nanopores may reduce the reaction conversions [123]. Thus, the surface hydrophobic modification of the nanopore may benefit fast diffusion of the substrate, which may, in turn, contribute to the improved activity. When a reaction involves incompatible substrates, such as oil and water, the amphiphilic modification of the nanopore microenvironment is a smart strategy because the amphiphilic nanopore should provide a microenvironment... 

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