Synthesis and characterization of novel nanomaterial Zn-MOF-NH2-ZIF-8@Cu based on MOF-on-MOF architecture and Cu nanoparticle as a stable nanocatalyst in solvent-free A3 coupling reaction

Metal-organic frameworks (MOFs) have aroused the interest of the majority of researchers due to their prominent features, especially in the field of heterogeneous catalysts. As state-of-the-art literature, this research designed and developed a new nanomaterial with a perfect crystalline nature through the combination of two MOFs. Here, the Zn-organic framework (Zn-MOF) as a 3D hybrid scaffold was synthesized, followed by functionalizing with urea ligand which contains two amine functional groups. The second step involved coating Zn-MOF-NH2 with zeolitic imidazolate framework-8 (ZIF-8) by the widespread growth of Zif-8 crystals on the surface of urea-modified Zn-MOF. Eventually, the new nanocomposite with MOF-on-MOF architecture was incorporated for the adsorption and stabilization of Cu nanoparticles through a simple liquid impregnation-reduction procedure. The chemical structure of ZIF-8 MOF was discussed and confirmed in detail by different analytical techniques. Based on the results, the Zn-MOF-NH₂-ZIF-8@Cu demonstrated unparalleled catalytic performance in the synthesis of propargyl amine derivatives. The prominent characteristics such as novelty, high surface area, wonderful catalytic activity, and excellent ability to reuse, make the Zn-MOF-NH₂-ZIF-8@Cu system an ideal paradigm in the developing of industrial-scale heterogeneous catalysts.