Fabrication of [Fe₃O₄@SiO₂@Si-(CH₂)₃-Bipyr][ZnₓClᵧ] as a Novel Magnetic Catalyst, and Its Utility for Construction of 𝐵𝑖𝑠-Coumarins and 𝐵𝑖𝑠(Pyrazolyl)Methanes

Initially, a novel magnetic catalyst namely [Fe3O4@SiO2@Si-(CH2)3-Bipyr][ZnxCly] (FSCBZ) was fabricated, and its structure was corroborated using energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric (TG), and vibrating-sample magnetometery (VSM) analyses. In continue, it was employed to catalyze the solvent-free construction of bis-coumarins (from aryl aldehydes and 4-hydroxycoumarin) and bis(pyrazolyl)methanes (from aryl aldehydes and 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one). The coumarin and pyrazole derivatives were attained in short times (10-20 min) and high yields (89-98%). FSCBZ was reusable for two times with retaining its catalytic performance.