N-Heterocyclic carbene palladium complex supported on ionic liquid-modified SBA-16: an efficient and highly recyclable catalyst for the Suzuki and Heck reactions

By grafting an N-heterocyclic carbene palladium complex and ionic liquid on the mesoporous cage-like material SBA-16, an efficient and highly recyclable heterogeneous catalyst for the Suzuki and Heck reactions was prepared. This catalyst afforded a fast conversion of the unactivated bromobenzene at a catalyst loading of 0.01 mol%, and a good yield was still achieved after the catalyst was reused ten times. Its recyclability was much better than that of the catalyst prepared from amorphous silica. The significantly enhanced recyclability could be attributed to the isolated nanocages of SBA-16 which could efficiently prevent the aggregation and agglomeration of Pd particles formed during the catalytic reaction into the less active large particles. The strategy for stabilizing metal nanoparticles using the isolated nanocages may be applied to other catalytic systems, in which the aggregation of metal nanoparticles is desired to be prevented.