Palladium Supported on Metformin-Functionalized Magnetic Polymer Nanocomposites: A Highly Efficient and Reusable Catalyst for the Suzuki-Miyaura Coupling Reaction

In this paper, a novel magnetically responsive nanocatalyst, Pd/Fe3O4@PMAA-Met (PMAA=poly(methacrylic acid), Met=metformin), has been successfully prepared by immobilizing palladium on the surface of metformin-functionalized magnetic polymer nanocomposites. This novel nanocatalyst was characterized by FTIR, XRD, TEM, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The prepared nanocatalyst showed excellent catalytic activity for Suzuki-Miyaura coupling reactions of aryl halides (I, Br, Cl) with arylboronic acids even at palladium loadings of 0.01-0.0007 mol% and the turnover frequency (TOF) reached up to 125714 h(-1). The excellent activity of this Pd/Fe3O4@PMAA-Met catalyst could be attributed to a "release and catch" catalytic mechanism as well as its nanometer size. This nanocatalyst could be simply separated with an external magnet and reused at least twelve times with excellent yields achieved.