Periodic mesoporous silica-immobilized palladium(II) complex as an effective and reusable catalyst for water-medium carbon–carbon coupling reactions

Ethyl-bridged periodic mesoporous organosilicas (PMOs) functionalized with diphenylphosphino (PPh2) ligands were synthesized by one-step evaporation-induced self-assembly (EISA), which were used as a support to immobilize Pd(II) organometallic catalyst by coordination reaction. The as-prepared Pd(II)–PPh2–PMO(Et) exhibited high activity in water-medium C–C coupling reactions and could be used repetitively. The high activity could be attributed to the high dispersion of Pd(II) active sites and ordered mesopore channels which effectively diminished the steric hindrance and thus, diffusion limit. Meanwhile, the ethyl-fragments and the PPh2-ligands in the support wall could synergic enhance surface hydrophobicity, which promoted the adsorption for organic reactant molecules.