Covalent attachment of 3-(aminomethyl)pyridine to graphene oxide: a new stabilizer for the synthesis of a palladium thin film at the oil–water interface as an effective catalyst for the Suzuki–Miyaura reaction

Abstract

This study describes the oxidation of graphite to graphene oxide (GO), followed by its covalent functionalization with 3-(aminomethyl)pyridine (3-ampy). A thin film was produced based on the reduction of the organopalladium(II) complex, [PdCl₂(cod)] (cod = 1,5-cyclooctadiene), at the toluene–water interface, in which the N group of the pyridine ring in 3-ampy helps in the uniform distribution of the Pd(0) nanoparticles (NPs) and also holds the particles strongly together during catalytic runs. The Pd/3-ampy-reduced-GO (rGO) nanohybrid was characterized using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The covalent functionalization reactions of GO include the formation of covalent bonds between the NH₂ functional group of 3-ampy and the epoxy group. Our studies show that the Pd/3-ampy-rGO nanohybrid is suitable for the Suzuki–Miyaura carbon–carbon coupling reaction. Compared to classical reactions, this method consistently has the advantages of well-dispersed Pd(0) NPs over the support, short reaction times, low catalyst loading, high yields and reusability of the catalyst without considerable loss of catalytic activity and a facile and low-cost method for the preparation of the catalysts. The Pd/3-ampy-rGO nanohybrid thin film showed highly improved catalytic activity toward aryl chloride derivatives as compared with other catalysts that have been reported.