Incorporation of Cyclodextrin into Mesostructured Silica

Abstract

The incorporation of cyclodextrin (CD) groups inside mesoporous silica frameworks was attempted using two methods: by the grafting of the CD groups into the channels of preformed mesoporous silica hosts and by the direct synthesis of CD-containing mesoporous materials by a one-step process. While the grafting procedure failed to incorporate CD groups inside the pore channels of mesoporous silica substrates, the direct synthesis approach yielded materials whose physical and chemical characteristics (as determined by X-ray diffraction, N2 sorptometry, transmission electron microscopy, and elemental analysis) were indicative of the presence of CD groups inside the pore channels of the materials. The CD-containing mesoporous materials, denoted as CD-HMS, were prepared by the co-condensation of tetraethoxysilane and a silylated derivative of β-cyclodextrin in the presence of a structure-directing dodecylamine surfactant solution. Materials with CD group loadings up to 0.39 mmol g-1 and uniform pore channels with diameters in the range of 38−42 Å were prepared by this method. Preliminary adsorption experiments using aqueous p-nitrophenol solutions showed that the CD-HMS materials were promising for the removal of organic compounds from water.