Synthesis of a novel nanomagnetic N4 bis schiff base complex of copper(ii) as an efficient catalyst for click synthesis of tetrazoles

In this study, we have prepared a novel bis-Schiff-base copper(II) complex by modifying Fe₃O₄ with acetylacetone functionalities and subsequently forming a Schiff base with 2-picolylamine and CuCl₂ through a template method. Immobilization of 2,4-pentanedione and its reaction with 2-picolylamine enabled the synthesis of 1,3-diketimines (HNacNac) as an anionic ligand. This unique design resulted in a tetradentate N₄ coordination sphere for copper(II) ion complexation. The resulting heterogeneous catalyst, [Fe₃O₄@Sil-Schiff-base-Cu(II)], efficiently catalyzed the click condensation of diverse aryl nitriles with sodium azide to produce 5-substituted 1H-tetrazoles in high yields and selectivity. The catalyst demonstrated remarkable stability and recyclability without appreciable loss of catalytic activity, as confirmed by hot filtration and reusability studies.