Ruthenium–bipyridine complexes bearing fullerene or carbon nanotubes: synthesis and impact of different carbon-based ligands on the resulting products

Abstract

This paper discusses the synthesis of two carbon-based pyridine ligands of fullerene pyrrolidine pyridine (C₆₀–py) and multi-walled carbon nanotube pyrrolidine pyridine (MWCNT–py) via1,3-dipolar cycloaddition. The two complexes, C₆₀–Ru and MWCNT–Ru, were synthesized by ligand substitution in the presence of NH₄PF₆, and Ru(II)(bpy)₂Cl₂ was used as a reaction precursor. Both complexes were characterized by mass spectroscopy (MS), elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy (IR), ultraviolet/visible spectroscopy (UV-VIS) spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and cyclic voltammetry (CV). The results showed that the substitution way of C₆₀–py is different from that of MWCNT–py. The C₆₀–py and a NH₃ replaced a Cl⁻ and a bipyridine in Ru(II)(bpy)₂Cl₂ to produce a five-coordinate complex of [Ru(bpy)(NH₃)(C₆₀–py)Cl]PF₆, whereas MWCNT–py replaced a Cl⁻ to generate a six-coordinate complex of [Ru(bpy)₂(MWCNT–py)Cl]PF₆. The cyclic voltammetry study showed that the electron-withdrawing ability was different for C₆₀ and MWCNT. The C₆₀ showed a relatively stronger electron-withdrawing effect with respect to MWCNT.