A novel magnetic mesoporous Fe₃O₄@Void@mSiO₂-Pd(0) nanochains with high heterogeneous catalysis efficiency for Suzuki coupling reaction

It is well known that palladium-catalyzed cross-coupling Suzuki reaction is very important way to build organic compound carbon skeleton. However, when some reactants such as chlorobenzene are used as substrates which has low reactivity, only moderately low yields were obtained using such kind of mobilized catalyst, Insufficient loading on the normal carrier, the problem of easy aggregation of palladium and large particle size of Pd were considered as reasons of it. A novel magnetic mesoporous Fe₃O₄@Void@mSiO₂ nanochains with yolk-shell structure have been first developed to solve the problems via magnetic-field induced distillation-precipitation polymerization together with a facile sol-gel method and the final calcination. Interestingly, we found that some pleated layers grown on the surface of Fe₃O₄@void@mSiO₂ nanochains during the hydrolysis of 3-aminopropyltriethoxysilane (KH-550) and special microstructures endow them with excellent porosity which are helpful for increasing the loading capacity of Pd nanoparticles. Owing to high aspect ratio and superparamagnetism, the magnetic nanochains can rotate in the water or organic solution and be separated and recycled easily with the drive of alternating magnetic field. In this catalysis system, the orderly mesoporous opening structure of the hollow mesoporous nanochains could effectively facilitate the transfer of reactant molecules, and the existence of the internal cavities would effectively prolong the action time of the Pd nanoparticles for the Suzuki reaction. The reaction yields of coupling reaction between bromobenzene/chlorobenzene and phenylboronic acid catalyzed by the nanochains can reach nearly 100% respectively. and the reaction yields can still maintain 92.93% and 60.86% after 7 cycles, respectively.