Functionalization of multi-walled carbon nanotubes by the baclofen drug to immobilize palladium nanoparticles and catalyze Sonogashira coupling reactions

The baclofen-MWCNTs-Pd nanocatalyst was synthesized through covalent grafting of baclofen molecules onto surface-modified carbon nanotubes and immobilizing Pd nanoparticles by the baclofen ligands. The chemical structure of the produced nanocatalyst was studied by Raman spectroscopy, Fourier transform-infrared spectroscopy, energy-dispersive spectroscopy (EDS), elemental mapping and inductively coupled plasma analysis. Also, its surface morphology was determined using the scanning and transmission electron microscopy techniques. Furthermore, the obtained baclofen-MWCNTs-Pd nanocatalyst is demonstrated to exhibit very high activity as a heterogeneous phosphine-free catalyst in Sonogashira cross-coupling of aryl halides by giving good to excellent yields of different products. In addition, the nanocatalyst can be reused four times without any significant leaching or loss of activity.