Fe₃O₄ And Pd?Pd/Ni?-Supported Catalyst:Synthesis And Catalyze Suzuki-Miyaura Cross-Coupling Reactions

Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions have become one of the most important organic reactions in the construction of carbon-carbon bonds.They have been widely used in the synthesis of natural products,pharmaceuticals and pesticides due to their mild reaction conditions,good functional compatibility and high production rate.Compared with the conventional homogeneous catalyst and heterogeneous catalyst,the catalyst which can be separated by a magnet has a unique advantage in separation and reuse.In addition,the unique structures and properties of the metal organic frameworks?MOFs?determine its wide application in many fields especially in catalytic.The post-synthetic modification?PSM?of MOFs can introduce palladium catalytic center,which allows MOFs play an important role in the Suzuki-Miyaura coupling reaction.In view of the above two points,the strategy of combining a covalent-coordination modification with nanoparticles?NPs?is used here for the post-synthetic modification?PSM?of [La?abdc??Habdc?·2H₂O]?La-MOF?,which has a high porosity and structure stability.First,the Fe₃O₄ nanoparticles were load in the synthesis process of La-MOF and Fe₃O₄@La-MOF was synthesized.Then Fe₃O₄@La-MOF was post-synthetically modified by reaction with pyridine-2-carboxaldehyde to give the imine derivative Fe₃O₄@La-MOF-Schiff base which was then coordinated with PdCl₂ to afford the palladium-functionalized framework Fe₃O₄@La-MOF-Schiff base-Pd.In addition,considering that the metal nickel was cheaper than palladium,the experiment further studied the catalytic activity of Fe₃O₄@La-MOF-Schiff-Pd/Ni.The characterization results such as X-ray powder diffraction analysis,thermogravimetric analysis,scanning electron microscopy?SEM?and transmission electron microscopy?TEM?,magnetism,EDS,XPS and ICP show that the Fe₃O₄ nanoparticles as well as the expected elements are distribute in composite materials in a homogeneous manner.In addition,the two new types of heterogeneous catalyst showed good catalytic activity in the Suzuki cross-coupling reactions and they can be separated easily just through an external magnet.More importantly,cycle experiments showed that both of the Pd and Pd/Ni loaded catalyst still keep high activity even they were used for many times.