Palladium within ionic liquid functionalized mesoporous silica SBA-15 and its catalytic application in room-temperature Suzuki coupling reaction

Initially, pore walls of mesoporous silica SBA-15 with template were modified with chlorotrimethylsilane. Then imidazolium salts were similarly incorporated covalently in the inner pore walls of mesoporous silica SBA-15 albeit without the template. Finally, palladium salts were introduced into the pore channels of the previously processed mesoporous silica via electrostatic interaction. The resulting palladium catalysts demonstrated exceptional activity for the room-temperature Suzuki coupling reaction in aqueous-organic mixed solvents and good recycling ability for at least 4–6 times. The turnover frequency of resulting catalysts could reach up to 84,000 h−1 at 50 °C. The corresponding samples were analyzed with solid-state NMR, FT-IR, XRD, nitrogen adsorption–desorption isotherms, TEM and XPS techniques. In addition, agglomeration of palladium catalyst in the Suzuki coupling reaction can be effectively controlled due to the stabilizing effect of the imidazulium salt and confinement of mesoporous walls.

Graphical abstractPalladium salts were introduced into the pore channels of the imidazolium salts-functionalized mesoporous silica SBA-15 via electrostatic interaction. The resulting palladium catalysts demonstrated exceptional activity for the room-temperature Suzuki coupling reaction in aqueous-organic mixed solvents and good recycling ability. In addition, agglomeration of palladium catalyst in the Suzuki coupling reaction can be effectively controlled due to the stabilizing effect of the imidazulium salt and confinement of mesoporous walls.Figure optionsDownload full-size imageDownload as PowerPoint slide