Sonochemically synthesized ferromagnetic Fe3O4 nanoparticles as a recyclable catalyst for the preparation of pyrrolo[3,4-c]quinoline-1,3-dione derivatives

This paper reports the green, rapid synthesis of Fe3O4 nanoparticles by the ultrasonic irradiation of Fe2O3 solution and Perilla frutescens (P. frutescens) leaf extract, which was used as both reducing and capping agent. The synthesized Fe3O4 nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis, vibrating sample magnetometry, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The FT-IR spectra indicated that the bioactive molecules present in the plant extract contain polyols, which act as a reducing as well as capping agent, as confirmed by TGA. TEM and SEM showed that the Fe3O4 nanoparticles were approximately spherical in shape with a mean size of 50 nm. The synthesized Fe3O4 nanoparticles exhibited ferromagnetic behavior with a saturation magnetization of 25.15 emu g(-1). The Fe3O4 nanoparticles, with their easy recovery by an external magnetic field, exhibited strong catalytic activity towards pyrrolo[3,4-c]quinoline-1,3-dione derivatives. These results suggest that the Fe3O4 nanoparticles produced can be applied as a catalyst in organic synthesis and recycled at least five times without significant loss in its activity.