Expanding the Horizon of Multicomponent Oxidative CouplingReaction via the Design of a Unique, 3D Copper Isophthalate MOFBased Catalyst Decorated with Mixed Spinel CoFe2O4 Nanoparticles

摘要

This work discloses the first ever magnetically retrievablecopper isophthalate-based metal-organic framework (MOF) decorated withsurface-modified cobalt ferrite (CoFe2O4) nanoparticles that have beenutilized as catalytic reactors for obtaining a relatively large number ofbiologically active benzimidazole scaffolds. A facile one-pot solvothermalapproach was employed for obtaining spherical and monodisperse CoFe2O4nanoparticles, which were subsequently modified using suitable protecting andfunctionalizing agents. Finally, these functionalized magnetic nanoparticleswere anchored onto the three-dimensional copper isophthalate MOF via acovalent immobilization methodology. The exploitation of advanced microscopic tools such as transmission electron microscopy and scanning electronmicroscopy provided valuable insights into the morphology of theimmobilized MOF. These results indicated that the surface-modified magneticnanoparticles had grown onto the surface of copper-5-nitroisophthalic acidMOF. A greener C?H functionalization strategy that involves the multicomponent oxidative cross-coupling between twodifferent set of amines (sp2-hybridized nitrogen-containing anilines and sp3-hybridized nitrogen-containing alkyl/aryl aminederivatives) and sodium azide has been incorporated to provide access to a broad spectrum of the value-added targetbenzimidazole moieties. It is interesting to note that this magnetic MOF-catalyzed protocol not only replaces toxic solvents withwater, which is a green solvent, but also enhances the economic competitiveness since the magnetic catalyst can be readilyrecovered and recycled for eight consecutive runs.