A versatile synthetic approach to periodic mesoporous organosilicas

A synthetic protocol for the preparation of a variety of high-quality periodic mesoporous organosilicas (PMOs) is presented. These nanostructured organosilicas have been synthesized by the acid-catalyzed hydrolysis and condensation of bis(triethoxysilyl) precursors containing different organic bridging groups. Polyoxyethylene(10) stearyl ether (Brij 76) is employed as the structure director using the surfactant template approach. Methylene, ethylene, ethenylene, and phenylene-bridged PMOs have been synthesized. Surfactant extraction is accomplished by refluxing the mesoscopic composite precipitates in acidified ethanol. The resulting PMOs have been characterized by nitrogen gas sorption, powder X-ray diffraction, ¹³C and ²⁹Si solid-state NMR, and high-resolution thermogravimetric analysis. These organosilicas exhibit large surface areas, narrow pore size distributions, and large total pore volumes. This is the first report of a synthetic protocol with the versatility to make high-quality PMOs containing aliphatic, aromatic, or olefinic carbon functional groups. This versatility is discussed in terms of template and precursor structures under the acidic reaction conditions.