OICC Press Iranian Journal of Catalysis 2345-4865 7 4 2024 02 03 A green synthesis of di-indolyloxindols catalyzed by CuO/g-C3N4 nanocomposite under mild conditions EN Ali Allahresani Department of Chemistry, Faculty of Science, University of Birjand, P. O. Box 97175-615, Birjand, Iran. Journal Article 2024 02 03 In this study, novel CuO/g-C3N4 nanocomposite was simply synthesized by impregnation of g-C3N4 with CuO nanoparticles. Then, the heterogeneous catalyst was characterized by various techniques including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Moreover, the Friedel–Crafts 3-indolylation reaction of isatin with indole derivatives in water as a green solvent was investigated using catalytic amount of CuO/g-C3N4 nanocomposite. The results showed that di-indolyloxindole derivatives are synthesized in good to excellent yields at mild conditions. Finally, this method has some advantages including the use of water as a green solvent, short reaction time, room temperature, easy work up and excellent yields. Keyword: CuO/g-C3N4 nanocomposite; di-indolyloxindols; indole; isatin.