Surfactant-Templated Organic Functionalized Mesoporous Silica with Phosphino Ligands

Abstract

Ordered organic functionalized mesoporous silica containing covalently bonded diphenylphosphinoethyl ligands was synthesized using a surfactant-templating approach. Briefly, hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) and 2-(diphenylphosphino)ethyl triethoxysilane (PPETS) in an acidic condition produced phosphino-ligand containing organosilicate species. Subsequent co-assembly of the organosilicate species with surfactants led to the formation of ordered organic/inorganic nanocomposites. Selective surfactant removal by controlled thermal decomposition created organic functionalized mesoporous silica with diphenylphosphinoethyl ligands covalently bonded to the silica framework. Pore structures and pore sizes of the functionalized mesoporous silica were controlled by using different surfactants such as P123, F127, Brij-58, and CTAB. It was found that the added organosilane may significantly affect the mesostructure possibly through participating in the cooperative assembly process. These organic functionalized mesoporous silicas were bonded with palladium ions, resulting in the formation of catalytically active organometallic complexes that show excellent activities in both Heck and epoxides allylation reactions. Compared with the conventional homogeneous catalysts, these heterogeneous organometallic complexes can be readily separated from the reaction systems and reused without deteriorating their catalytic activities. This study provides a direct synthesis approach to efficiently synthesize a large variety of organic functionalized mesoporous silica with controlled pore sizes, pore surface chemistry, and pore structure for heterogeneous catalysts and other applications.

Adsorption Process of Molecularly Imprinted Silica for Extraction of Lactose From Milk

“…In the region around 3400 cm -1 are stretches of silanol hydroxyl groups and also of molecules adsorbed on the surface of the oxide through hydrogen bonding. A broad and intense band between 3300 and 3700 cm -1 is associated with Si-OH groups and -OH stretching in Hbonded water, due to adsorption of water molecules on the surface of the pore channels (Hu et al, 2005). The band in the 1630 cm -1 region for deformations of water molecules can confirm the presence of water.…”

CO2‐promoted Water‐medium Ullmann Reaction over a Pd/Phenyl‐SBA‐15 Mesoporous Catalyst

“…As shown in Figure 4, both the Ph-SBA-15 and the Pd/Ph-SBA-15 display a typical type-IV N 2 adsorptiondesorption isotherm similar to that of the pure SBA-15, indicating the preservation of the mesoporous structure after grafting Ph-groups and even depositing Pd nanoparticles. 18 From the small-angle XRD patterns ( Figure 5) it could be seen that, similarly to SBA-15, the Ph-SBA-15 also displays a strong peak around 2θ＝0.8°～ 0.9° indicative of (100) diffraction, indicating the longrange ordered hexagonal mesoporous structure. 15 The Ph-modification and Pd-deposition caused a decrease in the peak intensity and even the disappearance of peaks characteristic of (110) and (200) diffractions since the incorporation of the Ph-groups into the SBA-15 pore channels might disturb the cooperative assembly of silica and P123 into a highly ordered mesoporous structure 16 and deposition of the metallic Pd particles might partially block the pore channels.…”

Preparation of Pd-Diimine@SBA-15 and Its Catalytic Performance for the Suzuki Coupling Reaction

“…The X-ray diffraction (XRD) patterns of SBA-15 and Pd-diimine@SBA-15 are shown in Figure 5. The SBA-15 sample exhibits three peaks at 2θ = 0.9°, 1.6°, and 1.9°, which correspond to (100), (110), and (200) facets, the characteristic diffraction peaks of mesoporous SBA-15 with a hexagonal geometry [38]. After SBA-15 was modified with diimine, its peak of (110) facet shifted to a lower angle and its intensity was obviously weakened.…”