Bio-inspired synthesis of Au NPs over the magnetic nanoparticles as an efficient catalyst for synthesis of biaryls and evaluation of its antioxidant activity

In the present study, a facile and modified technique for the immobilization of Au(0) NPs on the surface of iron oxide nanoparticles in the presence of Pomegranate juice has been adopted. The finely divided Au NPs were found to be well distributed over the Fe₃O₄ NPs surface. The as synthesized Au-Pomegranate@Fe₃O₄ material was characterized by different physicochemical techniques like TEM, EDX, FESEM, elemental mapping, VSM and ICP-OES in order to ascertain the structural and elemental identity. TEM analysis suggested the material is alike a solid solution and Au NPs were 30 nm sized. The Au active species were distributed homogeneously, being validated by mapping study. The VSM analysis also justified it to have saturation magnetization (Ms) value of 28.9 emu/g, sufficient to be attracted by external magnets. The novel material was catalytically investigated in the synthesis of wide range of biaryls following Ullmann homocoupling method. In all the reactions outstanding results were obtained except for chloroarenes and the sterically hindered substrates. Iodoarenes produced the best yield with 90–96 % range. The catalyst robustness and heterogeneity was determined by hot filtration test and it could be reused for 9 successive cycles without any significant loss in activity. Additionally, the biological property of the Au-Pomegranate@Fe₃O₄ nanocomposite was examined by assessing its antioxidant effects. Antioxidant activity was evaluated through DPPH radical scavenging assays, where the IC₅₀ value was determined to be 98.2 µg/mL.