Layered hybrid materials (LHMs) based on ordered silicoaluminate sheets linked with organic fragments, perpendicularly located and stabilized in the interlayer space, were synthesized by one-pot direct hydrothermal process, in absence of structural directing agents (SDAs), and using bridged silsesquioxanes as organosilicon precursors. By following the synthesis described here, the preliminary preparation of inorganic layered precursors, post-synthesis swelling and/or pillaring treatments can be avoided. The physico-chemical and structural characteristics of the materials were studied by chemical and thermogravimetrical analyses, X-ray diffraction, TEM microscopy, spectroscopic techniques (NMR and FTIR) and textural measurements. The complete exchange of intracrystalline sodium cations by protons, without substantial structural alteration of hybrid materials, facilitated the generation of hybrid materials, which contained acid and base sites located in the inorganic (silicoaluminate layers) and in the organic interlayer linkers, respectively, being the resultant acid-base materials active and selective catalysts.
Novel bifunctional acid-base monolayered hybrid catalysts (MLHMs), based on associated individual (organo)aluminosilicate sheets with amino and sulfonic pending groups located in the interlayer space, have been successfully prepared by direct alkaline hydrothermal synthesis and evaluated in consecutive catalytic transformations. Different characterization techniques such as chemical and thermogravimetrical analyses, X-ray diffraction, TEM microscopy, nuclear magnetic resonance (NMR), temperature programmed desorption of CO2 and NH3 (TPD), and textural measurements were used to show physico-chemical and structural nature of the materials, evidencing their effectivity as functional acid, base and acid-base catalysts for different one-pot two-step tandem reactions, which were performed in presence of only one active and recoverable lamellar-type hybrid solid catalyst.
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