Copper(II) Oxide Nanoparticles Impregnated on Melamine‐Modified UiO‐66‐NH₂ Metal–Organic Framework for C–N Cross‐Coupling Reaction and Synthesis of 2‐Substituted Benzimidazoles

Abstract

A zirconium‐based metal–organic framework, UiO‐66‐NH2, modified by melamine (Mlm) was used as a support for CuO nanoparticles (NPs). Melamine offered a platform for uniform and homogeneous distribution of NPs on the surface of the frameworks and made a strong bonding to the NPs to avoid undesirable leaching. UiO‐66‐NH2‐Mlm/CuO NPs were used for the Buchwald–Hartwig C–N cross‐coupling reaction to synthesize arylated anilines from phenyl iodide, bromide, and chloride and primary and secondary amines in DMF at 110°C. The catalyst was also employed for the synthesis of 2‐substituted benzimidazole derivatives from various aromatic aldehydes and o‐phenylenediamine in the absence of an oxidant in EtOH at room temperature. The catalyst was recyclable and reusable for several times and exhibited good stability (examined by BET, XRD, and SEM–EDX) in reaction conditions.

Recent advances in the application of nanocatalysts in C‐N coupling reactions

“…The immobilization of CuO NPs on the melamine‐modified zirconium‐based MOF, UiO‐66‐NH 2 was reported by Jafarzadeh and co‐workers [ 196 ] in 2019. To prepare UiO‐66‐NH 2 ‐Mlm/CuO NPs, first, UiO‐66‐NH 2 MOF was synthesized from the reaction of ZrCl 4 and 2‐aminoterephthalic acid in DMF and then functionalized with cyanuric chloride (CC).…”

“…In the following, the [195] Royal Society of Chemistry F I G U R E 3 Preparation of UiO-66-NH 2 -Mlm/CuO. Reprinted with permission from Najari et al [196] Copyright 2019 John Wiley and Sons chloride functional groups of the grafted CC were replaced with amine groups by the addition of NH 3 , resulting in the formation of UiO-66-NH 2 -Mlm. In the final step, Cu (II) ions were supported by amine groups on the surface of UiO-66-NH 2 -Mlm and next transformed to CuO NPs using NaBH 4 at room temperature (Figure 38).…”

“…Preparation of UiO‐66‐NH 2 ‐Mlm/CuO. Reprinted with permission from Najari et al [ 196 ] Copyright 2019 John Wiley and Sons…”