Effective fabrication of poly(anilin-formaldehyde)-supported hybrid nanomaterial and catalytic synthesis of dihydropyridines

In this study, Fe3O4@SiO2-PAF-SO3H nanocomposite was successfully fabricated by immobilization of sulfonic acid groups on the surface of poly(anilin-formaldehyde)-supported on magnetic Fe3O4@SiO2 nanoparticles through layer-by-layer assembly. Fe3O4@SiO2-PAF-SO3H composite nanostructure has been fully characterized using various techniques including the Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction patterns (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometry (VSM). The one-pot synthesis of mono and bis 1,4-dihydropyridine derivatives, as pharmaceutically interesting compounds, have been achieved in high yields via three-component and pseudo five component condensation of an aromatic aldehyde, ammonium acetate and ethyl acetoacetate in the presence of Fe3O4@SiO2-PAF-SO3H as a novel retrievable hybrid nanocatalyst under solvent-free conditions. This protocol has advantages in terms of short reaction time, solvent-free condition, high yield and purity, easy work-up and eco-friendly process as well as recyclability of the nanocatalyst (at least 6 times) with no decrease in catalytic activity.