Bio-decorated gold nanoparticles over the surface of graphene oxide mediated by Orange leaves extract as efficient catalyst for synthesis of propargylamines and evaluation of its antioxidant activity

A novel and eco-friendly approach for creating gold nanoparticles (Au NPs) integrated with graphene oxide modified by Orange leaves extract has been introduced. The phytoconstituents found in Orange leaves extract, owing to the presence of polyhydroxyl groups, aided in the green reduction of gold ions on the graphene oxide surface, resulting in the formation of the GO/AuNPs nanocomposite. The produced nanocomposite underwent characterization through FE-SEM, EDX, elemental mapping, ICP, and TEM analysis. TEM imaging illustrated that the gold nanoparticles displayed a spherical shape, were mono-dispersed, and had an approximate diameter of 10–20 nm. The GO/Au NPs' catalytic efficiency was evaluated in a three-component reaction combining amines, alkynes, and aldehydes (A3 coupling) to produce derivatives of propargylamines. After being recovered by centrifugation, the GO/Au NPs catalyst showed enough stability to be used again for seven consecutive cycles with negligible activity loss. Additionally, by evaluating the antioxidant effects of the GO/Au NPs, their biological properties were investigated. DPPH radical scavenging experiments were used to assess antioxidant activity, and the IC50 value was found to be 97.6 µg/mL.