Molecular imprinting of surfaces of mesoporous sorbents is a novel method for introducing template-selective recognition sites. This method makes use of the unique surface environment of hexagonally packed mesopore surfaces of selected pore sizes (see the schematic representation) and coats such surfaces with functional ligands by binding to a metal ion template.

Mesoscopic organosilicas were synthesized with bis(triethoxysilyl)ethane (BTSE) and cetyltrimethylammonium chloride (CTAC) under basic conditions. Further functionalization was achieved by co-condensation with trialkoxyorganosilanes. Surfactant extraction produced periodic mesoporous organosilicas (PMO's) functionalized with the respective organosilane pendent groups. Organosilanes used in this study include: 3-aminopropyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 2-(trimethoxysilylethyl)pyridine, n-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, phenethyltrimethoxysilane, and benzyltriethoxysilane. These materials have been characterized by nitrogen gas adsorption, powder X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), elemental analysis (EA), and high-resolution thermogravimetric analysis (TGA). The effect of organosilane incorporation on the porous structure of these materials is examined.

No abstract

Methylene-, ethylene-, and phenylene-bridged periodic mesoporous organosilicas (PMOs) synthesized with nonionic alkylethylene oxide templates exhibited significantly better mechanical and hydrothermal stabilities than periodic mesoporous silica. Synthesis of PMOs utilized the acid-catalyzed hydrolysis and condensation of bis(triethoxysilyl) precursors around supramolecular polyoxyethylene(10) stearyl ether (Brij 76) templates. Nitrogen gas sorption, thermogravimetry, and X-ray diffraction have been used to characterize the effects of aging, mechanical compression, and hydrothermal treatment on these materials. Both as-synthesized composites containing surfactant templates and extracted PMOs showed no degradation after 10 months. The enhanced stability of these nanoporous organosilicas relative to meoporous silica makes them potential candidates for use in advanced catalysis and adsorption applications.