- Synthesis of new microporous layered organic-inorganic hybrid nanocomposites by alkoxysilylation of a crystalline layered silicate, ilerite
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We have developed microporous organic-inorganic hybrid nanocomposites by alkoxysilylation of 4,4′-biphenyl-bridged alkoxysilane compounds, which contain triethoxysilyl, methyldiethoxysilyl, and dimethylethoxysilyl groups at each end of the 4,4′-biphenylene unit ((CH3)n(C 2H5O)3-n-Si-C12H8-Si- (OC2H5)3-n(CH3)n, n = 0, 1, or 2, abbreviated as BESB(0), BESB(2), or BESB(4), respectively, where the number in parentheses indicates the number of methyl groups in these molecules), in the interlayer of a crystalline layered silicate, ilerite. XRD, 29Si solid-state NMR and fluorescence spectroscopy revealed the immobilization and bridging formation of the BESB molecules between the silicate layers by condensation, not only with H-ilerite, but also with the BESB molecules. The interlayer structures exhibited different molecular arrangements. BESB(0) and BESB(4) molecules are present as a monolayer arrangement in which BESB(0) molecules form the oligomeric species caused by close stacking like a dimer. BESB(2) molecules form mainly bilayer-like aggregates in the interlayer. The structural differences are caused by the different reactivities of the BESB molecules, which control their polymerization in the interlayer. The resultant BESB(0)- and BESB(2)-ilerite had high microporosity with BET surface areas (508 and 578 m2 g-1 for BESB(0)- and BESB(2)-ilerite, respectively). The micropores showed higher toluene adsorptivity than several other porous silica materials due to the successful surface modification. Consequently, this approach provides a new method for constructing novel microporous nanocomposites, the key to improved selectivity and activity in separation and catalytic applications. The Royal Society of Chemistry 2006.
- Ishii, Ryo,Ikeda, Takuji,Itoh, Tetsuji,Ebina, Takeo,Yokoyama, Toshirou,Hanaoka, Takaaki,Mizukami, Fujio
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- Arylsilsesquioxane Gels and Related Materials. New Hybrids of Organic and Inorganic Networks
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Molecular building blocks for the preparation of amorphous hybrid organic-inorganic network materials have been synthesized. Hydrolysis and condensation of bis(triethoxysilyl)aryl 1-4 and -ethynyl 5 monomers results in formation of aryland ethynyl-bridged polysilsequkwanes in the form of xerogels. The gels were glasslike materials composed of uniform aggregates of particles between 50 and 80 nm in diameter. Atomic force microscopy was used to examine the fine grained aggregate characteristics of phenyl-bridged polysilsesquioxanes. The aryl-bridged materials were microporous with surface areas as high as 1000 m2/g and thermally stable to 400 °C in air. Solid state 13C and 29Si NMR spectroscopies were used evaluate the integrity of the aryl and ethynyl bridges and to determine the degrees of hydrolysis (semiquantitative) and condensation in the network materials.
- Shea,Loy,Webster
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p. 6700 - 6710
(2007/10/02)
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