Cr- and Zn-substituted cobalt ferrite nanoparticles supported on guanidine-modified graphene oxide as efficient and recyclable catalysts

Cr- and Zn-substituted cobalt ferrite nanoparticles supported on guanidine-grafted graphene oxide nanosheets, CrCoFeO4@G-GO and Zn0.5Co0.5Fe2O4@G-GO, were synthesized and characterized by flame atomic absorption spectroscopy, inductively coupled plasma optical emission spectrometer, energy-dispersive spectroscopy, FT-IR spectroscopy, UV-Vis spectroscopy, x-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett, and Teller analysis. The potential of synthesized catalysts has been investigated in the aerobic oxidation of alkyl arenes and alcohols to the corresponding aldehydes and ketones and one-pot tandem oxidative synthesis of 2-phenylbenzo[d]oxazole derivatives. The results show that CrCoFeO4@G-GO and Zn0.5Co0.5Fe2O4@G-GO catalysts exhibit high catalytic activity and selectivity in the oxidation reactions in the absence of any other oxidizing reagent or initiator.