Chemoselective reduction of nitro and nitrile compounds using an Fe(3)O(4)-MWCNTs@PEI-Ag nanocomposite as a reusable catalyst

Multi-walled carbon nanotubes (MWNTs) were modified with carboxylic acid functional groups (MWCNTs-(COOH)(n)) prior to decoration with Fe(3)O(4) nanoparticles. A further modification step by polyethyleneimine (PEI) resulted in Fe(3)O(4)-MWCNTs@PEI which provided a suitable platform for coordination and in situ reduction of silver ions to obtain an Fe(3)O(4)-MWCNTs@PEI-Ag nanocomposite with highly dispersed Ag nanoparticles. The Fe(3)O(4)-MWCNTs@PEI-Ag hybrid material was characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), and was used as an efficient catalyst for chemoselective reduction of nitroaromatic and nitrile compounds to their corresponding amines in aqueous solution at ambient temperature. Nitrofurazone, a cytotoxic antibiotic, as a non-aromatic example was also reduced selectively at the nitro group without reduction of the other functionalities in the presence of Fe(3)O(4)-MWCNTs@PEI-Ag. The catalyst was magnetically recoverable and maintained its activity for at least six cycles without considerable loss of efficiency.