Stabilization of Palladium-Nanoparticle-Decorated Postsynthesis-Modified Zr-UiO-66 MOF as a Reusable Heterogeneous Catalyst in C–C Coupling Reaction

Abstract

Here we prepared a highly efficient and reusable catalyst by a step-by-step postsynthesis modification of UiO-66-NH₂ metal-organic frameworks (MOFs) with nitrogen-rich organic ligands and used it as support for the preparation of UiO-66-NH₂@cyanuric chloride@2-aminopyrimidine/Pd_NPs. The catalytic performance's results of UiO-66-NH₂@cyanuric chloride@2-aminopyrimidine/PdNPs, UiO-66-NH₂/PdNPs, and UiO-66-NH₂@cyanuric chloride/PdNPs indicate high efficiency of the modulation of the microenvironment of the palladium NPs. The addition of N-rich organic ligands through postsynthesis modification caused a unique structure of the final composite in favor of the progress of the C-C coupling reaction. Various techniques, including FT-IR, XRD, SEM, TEM, EDS, and elemental mapping, were used to characterize UiO-66-NH₂@cyanuric chloride@2-aminopyrimidine/Pd_NPs, indicating its successful preparation. Three C-C coupling reactions, including the Suzuki, Heck, and Sonogashira coupling reactions, were promoted using the produced catalyst. As a result of the postsynthesis modification (PSM), the proposed catalyst displays improved catalytic performance. In addition, the suggested catalyst was highly recyclable up to ten times without leaching of PdNPs.