Complexation of guanidino containing l-arginine with nickel on silica-modified Hercynite MNPs: a novel catalyst for the Hantzsch synthesis of polyhydroquinolines and 2,3-Dihydroquinazolin-4(1H)-ones

In this study, a novel amino acid-based Ni complex was immobilized on SiO2-modified Hercynite magnetic nanoparticles as the support to prepare the heterogenized guanidino-nickel catalyst (Hercynite@SiO2-l-Arginine-Ni). The uniform surface morphologies of these nanoparticles were characterized using SEM. Thermogravimetric analyses indicated that the [Hercynite@SiO2-l-Arginine-Ni] nanocomposite possessed reliable thermal stability. The homogeneous dispersion of nickel species on the surface of the amino acid-modified Hercynite was characterized using X-ray mapping and XRD. The catalysis studies showed that this heterogenized l-Arginine-Ni magnetic complex was highly active for the asymmetric Hantzsch synthesis of polyhydroquinolines and cyclocondensation of anthranilamide with aromatic aldehydes to generate 2,3-dihydroquinazolin-4(1H)-ones. In addition, the magnetic and heterogeneous nature of Hercynite core allows the easy separation of the catalyst by magnetic decantation. Besides, the [Hercynite@SiO2-l-Arginine-Ni] can be reused for at least 5 catalytic cycles for both of the mentioned reactions without an obvious drop in its activity.

Automated summary

In this study, a novel amino acid-based Ni complex was immobilized on SiO2-modified Hercynite magnetic nanoparticles to prepare a highly active catalytic system for various reactions. The heterogenized catalyst showed excellent thermal stability and could be easily separated and reused due to its magnetic and heterogeneous nature.