In situ immobilized palladium nanoparticles on surface of poly-methyldopa coated-magnetic nanoparticles (Fe3O4@PMDA/Pd): A magnetically recyclable nanocatalyst for cyanation of aryl halides with K4[Fe(CN)6

Abstract

Poly-methyldopa (PMDP)-coated Fe3O4 nanoparticles (Fe3O4@PMDP) have been synthesized through a simple and green procedure. In the present study, for the first time, Pd nanoparticles were successfully deposited using Fe3O4@PMDP as a core-shell magnetic coordinator and stabilizer agent. In this protocol, Pd ions were adsorbed on surfaces of Fe3O4@PMDP through immersion of the PMDP-coated Fe3O4 nanoparticles into a palladium plating bath. Next, they were reduced in situ to palladium nanoparticles using PMDP’s N-containing groups and reducing ability. The structure, morphology and physicochemical properties of the synthesized nanoparticles were characterized by different analytical techniques such as energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, high resolution transmission electron microscopy (HR-TEM), inductively coupled plasma (ICP), thermo gravimetric analysis (TGA), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). Core-shell Fe3O4@PMDP/Pd(0) nanoparticles showed excellent catalytic performance as a reusable nanocatalyst for cyanation of aryl iodides and bromides with K4[Fe(CN)6] as the cyanating agent. The nitriles were obtained in good to excellent yield and the catalyst can be recycled and reapplied up to seven times with only very slight decrease in its catalytic performance.