NH2- or PPh2-functionalized linkers for the immobilization of palladium on magnetite nanoparticles?

Immobilization of palladium on magnetite nanoparticles has been carried out with the assistance of two differently functionalized linkers containing phosphino- or amino-terminated groups. The linkers have been anchored to the magnetite surface by means of catechol, mercapto or carboxylate groups. The nature of the resulting Pd nanoparticles deposited has been examined by HAADF-STEM images and XPS electron spectroscopy. The efficiency of the two kinds of catalysts has been checked and compared for the Suzuki–Miyaura reaction, 4-nitrophenol reduction and styrene hydrogenation. The results evidence that the nanoparticles equipped with the phosphino fragment are better catalysts than those functionalized with the amino group and, in some processes, they are among the most active catalysts reported in the literature