Magnetically Recyclable Pd@UiO-66@Fe3O4 Ternary Composites as Efficient Heterogeneous Catalysts for Suzuki–Miyaura Cross-Coupling Reaction

In this study, a novel magnetic metal–organic framework (MOF) composite, Pd@UiO-66@Fe3O4, was successfully synthesized as a high-performance heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction. The material was prepared by loading nano-sized carboxylated Fe3O4 onto UiO-66 via an in situ solvothermal method, followed by the encapsulation of Pd nanoparticles using an ultrasound-assisted dual-solvent method (DSA). Characterization results, including PXRD and TEM, confirmed that the ternary composite retains the structural integrity of UiO-66 while incorporating magnetic functionality and well-dispersed Pd active sites. The catalyst exhibited high catalytic performance for the coupling of aryl iodides and aryl boronic acids. Furthermore, the catalyst demonstrated good compatibility with the substrates examined and excellent stability. Due to the integration of carboxylated Fe3O4, the composite could be easily separated from the reaction mixture using an external magnet and reused for at least five cycles without a significant loss in catalytic activity. The high activity and durability are attributed to the integrated roles of the Pd nanoparticles, the porous MOF support, and the magnetic Fe3O4 component, which respectively provide catalytic active sites, structural stabilization/dispersion, and magnetic recoverability.