Mesoporous silica nanoparticles (MSNs) with controlled size and morphology displays attractive properties such as, high specific surface area, high thermal, chemical and mechanical stability, low toxicity, high compatibility, making them ideal candidates for number of applications. Because of the nanometric dimensions, their isolation from reaction medium is generally challenging. Commonly used strategy is to incorporate magnetic nanoparticles such as magnetite (Fe3O4) NPs into the silica network to impart super paramagnetic properties to MSNs which enable their isolation simply by applying external magnetic field.1
In this work, we have developed magnetic MSNs and utilized it as catalyst support for immobilization of palladium catalysts. The magnetic MSNs with surface area of 1909 m2/g were successfully synthesized via nanoemulsification process of hydrophobic magnetite nanoparticles dispersed in chloroform in the presence of surfactant cetyltrimethylammonium bromide followed by addition of tetraethoxysilane and its polycondensation via a sol-gel route. The MMSNs were modified with phosphine and N-heterocyclic carbene based ligands, which provides coordination sites for conjugating with catalytic species. Subsequently, palladium catalyst was immobilized on the surface and within the pores of the MMSNs and was subjected to the carbonylative Sonogashira coupling reaction of aryl iodide with terminal alkynes.2 The catalytic system demonstrated high catalytic activity, and was easily and effectively recovered from the reaction mixture simply by applying an external magnetic field. Preparation, characterization and the catalytic application will be presented.