Magnetic chitosan supported covalent organic framework/copper nanocomposite as an efficient and recoverable catalyst for the unsymmetrical hantzsch reaction

Abstract

The fabrication of magnetic porous nanocomposites is of great significance owing to their excellent properties and their application as promising catalysts. Herein, a novel covalent organic framework (COF)-modified magnetic chitosan (CS) supported copper (Fe3O4/CS/COF/Cu) nanocomposite was prepared through modification of Fe3O4 with CS, chemical attachment of melamine-rich COF on Fe3O4/CS followed by reaction with Cu(NO3)2·3H2O. The resulting nanocomposite was characterized by FT-IR, XRD, SEM, TEM, EDX, BET and VSM analyses. Fe3O4/CS/COF/Cu possesses large specific surface area and supermagnetism, making it an ideal catalyst for the organic reactions. Thus, Fe3O4/CS/COF/Cu was applied as an efficient and recoverable catalyst for the green and rapid synthesis of biologically active polyhydroquinoline derivatives via the unsymmetric Hantzsch reaction under solvent-free conditions. Fe3O4/CS/COF/Cu exhibits high reactivity and selectivity for the preparation of different derivatives of polyhydroquinolines under mild reaction conditions and short time. Furthermore, the catalyst was recovered and reused several times without an important decrease in efficiency.