Reduced zwitterionic graphene oxide sheets decorated with nickel nanoparticles as magnetically and efficient catalyst for A(3)-coupling reactions under optimized green experimental conditions

A Ni-based supported reduced zwitterionic graphene oxide N,N-bis(2-pyridylmethyl)ethylenediamine 1,3-propanesultone (GO-BPED-PS) material was prepared for the catalysis of A(3)-coupling reactions under green experimental conditions. First, the in situ generation of nickel nanoparticles (NiNPs) onto the reduced zwitterionic GO-BPED-PS sheets was characterized by various techniques such as Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) analysis. Moreover, the electron density map of NiNPs onto the reduced zwitterionic GO-based sheets was produced through the X-ray crystallographic analysis. Then, the as-prepared reduced GO-BPED-PS NiNPs (rGO-BPED-PS@NiNPs) material was used as a heterogeneous catalyst for the three-component coupling reaction (A(3)-coupling reaction) of benzaldehyde, morpholine, and terminal alkynes. The experimental conditions were performed in order to obtain very good green chemistry metrics. In particular, we obtained a high catalytic efficiency when using gamma-valerolactone as solvent, a reaction time of 3 h and a temperature of 100 degrees C. In addition, it was demonstrated that the rGO-BPED-PS@NiNPs catalyst could be recycled for 11 times without a significant decrease in its catalytic activity.