Ordered and Hydrothermally Stable Cubic Periodic Mesoporous Organosilicas with SBA-1 Mesostructures: Synthesis, Characterization, Solid-State NMR Spectroscopy, and DFT Calculations

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• 作者：Yu-Chi Pan^† ; ; Hao-Yiang Wu^‡ ; ; Guang-Liang Jheng^† ; ; Hui-Hsu Gavin Tsai*^† ; ; Hsien-Ming Kao*^† ;
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：February 19, 2009
• 年：2009
• 卷：113
• 期：7
• 页码：2690-2698
• 全文大小：227K
• 年卷期：v.113,no.7(February 19, 2009)
• ISSN：1932-7455

文摘

Periodic mesoporous organosilicas (PMOs) based on the cubic SBA-1 mesostructure (Pm3n mesophase) were synthesized by co-condensation of tetraethoxysilane (TEOS) and 1,2-bis(triethoxysilyl)ethane (BTEE) under acidic conditions using cetyltriethylammonium bromide (CTEABr) as a structure-directing agent. The ethane-bridged PMO materials thus obtained were characterized by powder X-ray diffraction (XRD), solid-state ¹³C and ²⁹Si NMR spectroscopy, thermogravimetric analysis (TGA), and nitrogen sorption measurements. The maximum BTEE contents that can be incorporated into the pore wall without degrading the Pm3n mesostructure were up to 60% (based on silica). The resulting materials were hydrothermally stable up to 120 h in boiling water with only a slight decrease in their structural properties, whereas the structure of the pure silica counterpart SBA-1 material was completely collapsed after such treatment. The presence of the ethane groups in the mesoporous wall led to a more hydrophobic environment and thus enhancement of hydrothermal stability, as revealed by water adsorption. The combined results of 2D ²⁹Si{¹H} heteronuclear correlation (HETCOR) NMR and density functional theory calculations suggested that the T³−T²−Q⁴−Q³ motif could be the favorable framework building unit in PMOs.