Cu Nanoparticles Supported on Fe₃O₄@SiO₂@N-Doped Carbon Core–Shell Nanocomposites for C–N Coupling Reactions in Water

Heterogenous copper nanoparticle (Cu NP) catalysts supported on magnetic nitrogen (N)-doped carbon–silica materials with a core–shell structure were fabricated by a facile one-pot hydrothermal carbonization reaction. The Cu NPs with a diameter of 10 nm were generated by an in situ process in which the Cu2+ was reduced by glucosamine. The N atoms doped into the magnetic nanocomposites were derived from glucosamine and anchored to the Cu NPs. The hydrophilicity of the carbon-based shell promoted uniform dispersion of the resulting core–shell nanoparticles in water. Moreover, the mesoporous carbon not only improved the mass transfer efficiency of the organic substrates to and from the catalysts but also prevented the Cu NPs from aggregating and leaching. Owing to these merits, the resultant magnetic nanocomposite particles Fe3O4@SiO2@GA/Cu exhibited excellent catalytic activity for aqueous C–N coupling reactions without any additives, as well as showed good universality toward different aryl halides and various nitrogen nucleophiles with moderate to excellent yields. More importantly, the Fe3O4@SiO2@GA/Cu catalysts were easily recovered using an external magnet and showed stable performance over five reaction cycles.