Green synthesis of predominant (1 1 1) facet CuO nanoparticles: Heterogeneous and recyclable catalyst for N-arylation of indoles

Well faceted CuO nanoparticles were synthesized by thermal-assisted green strategy at reflux temperature in a short period of time. A possible growth mechanism of such highly faceted nanostructures based on typical biomolecule-crystal interactions in aqueous solution is tentatively proposed. The large surface area (223.36 m2/g) and rich exposed active sites are expected to endow such nanostructures with excellent performances in catalysis as demonstrated here for remarkable catalytic activity with respect to the N-arylation of indoles. Nanoparticles were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Both the activity and selectivity of the N-arylation reactions could be tuned by varying the concentration of CuO nanoparticles. Nanoparticles catalyst were recycled and reused for further catalytic reactions with minimal loss in activity. A variety of indole derivatives afforded corresponding N-arylation product with excellent yields (up to 98%).

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (81 K)Download as PowerPoint slideHighlights► Green synthesis of predominant (1 1 1) facets CuO nanoparticles. ► The predominant (1 1 1) facets, which are expected to be chemically and dynamically active and therefore catalytically active. ► A variety of indoles derivatives afforded the corresponding N-arylated products with excellent yields (up to 98%). ► The nano CuO recycled for at least for five times without loss of its catalytic activity.