Periodic mesoporous organosilicas (PMOs) based on the cubic SBA-1 mesostructure (Pm3n mesophase) were synthesized by co-condensation of tetraethoxysilane (TECS) 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 C-13 and Si-29 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 Si-29 {H-1} heteronuclear correlation (HETCOR) NMR and density functional theory calculations suggested that the T-3-T-2-Q(4)-Q(3) motif could be the favorable framework building unit in PMOs.
