Graphene Quantum Dot Modified Fe₃O₄ Nanoparticles Stabilize PdCu Nanoparticles for Enhanced Catalytic Activity in the Sonogashira Reaction

Abstract

In this report, Fe3O4 nanoparticles are modified for the first time with graphene quantum dots (GQD) and used for the stabilization of PdCu bimetallic nanoparticles. The new magnetic compound, PdCu@GQD@Fe3O4, is characterized by different methods such as SEM, high‐resolution (HR)‐TEM, energy‐dispersive X‐ray spectroscopy (EDS) mapping, XRD, and X‐ray photoelectron spectroscopy (XPS). This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N‐dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading. According to different tests, such as polyvinylpyridine poisoning, hot filtration, and kinetic studies, this catalyst works under heterogeneous conditions. By magnetic separation of the catalyst, it can be recycled for six consecutive runs with only a small decrease in activity without appreciable structural modification of the reused catalyst, which is characterized by TEM and XPS.

Characterization of a Poly‐4‐Vinylpyridine‐Supported CuPd Bimetallic Catalyst for Sonogashira Coupling Reactions

“…Recently, the presence of Cu in CuPd NPs proved to significantly enhance the catalytic performances of Pd catalysts in carbon–carbon coupling reactions (e.g. Suzuki–Miyaura and Sonogashira reactions) allowing the development of new CuPd catalysts that require also a reduced amount of precious Pd metal …”

Iron oxide modified with pyridyl‐triazole ligand for stabilization of gold nanoparticles: An efficient heterogeneous catalyst for A3 coupling reaction in water

“…X‐ray diffraction (XRD) analysis of the prepared catalyst showed the presence of Fe 3 O 4 NPs by screening Bragg's reflections at 2 θ = 30.18°, 35.5°, 43.4°, 53.5°, 57.2° and 62.8° corresponding to the (210), (311), (400), (422), (511) and (440) planes of Fe 3 O 4 NPs, respectively . Due to low loading weight of Au, peaks relating to metallic gold were weak and appeared at 2 θ = 38°, 44.2°, 65° and 78° (Figure ) …”

Solid-Supported Palladium Catalysts in Sonogashira Reactions: Recent Developments

“…Regardless of the carbon-derived material employed as support, the stability and catalytic activity of supported PdNPs in the Sonogashira coupling can be improved following different strategies. One of them consists in the formation of an alloy with another metal, such as Au [57], Ni [58], Co [59][60][61], and Cu [62][63][64]. Thus, palladium-based alloys display promising catalytic activity in the Sonogashira cross-coupling reaction, as this approach usually slows down the undesired nanoparticle aggregation without altering the initial shape of the PdNPs.…”

“…PdCu alloy nanoparticles supported on graphene-derived materials have been efficiently used in the Sonogashira coupling of aryl halides with aliphatic and aromatic terminal alkynes [62][63][64]. Particularly interesting has resulted the use of PdCuFeNPs supported on reduced graphene oxide (PdCuFeNPs@RGO), which has shown higher efficiency than the corresponding PdCuNPs@RGO analogue in the Sonogashira coupling of a wide range of aryl halides with phenylacetylene, using potassium hydroxide as base and cetyltrimethylammonium bromide as additive in water as solvent [63].…”