Unveiling the dual-function applications of a magnetically retrievable chemically grafted Schiff base Cu-complex on graphene oxide for catalytic and antibacterial applications†

In the current work, a new Schiff base complex containing Cu(II) ions was covalently anchored in a stepwise manner onto graphene oxide nanosheets, followed by a combination with magnetic iron oxide, to form a potential catalyst for C–H functionalization of indoles on C-3 via a one-pot multicomponent reaction. Numerous methods were used to characterize the as-synthesized nanostructure (CuSB-GO/FO), including VSM, XRD, FT-IR, SEM, EDX, TEM, Raman spectroscopy, N₂ adsorption–desorption measurement and ICP-AES techniques. The as-synthesized CuSB-GO/FO was evaluated as an effective and versatile catalyst for reactions of different indoles, malononitrile, and substituted benzaldehydes in ethanol/water at 35 °C, producing 3-substituted indoles. The key advantages of this catalytic system are its quick reaction time, high product yield, use of green solvents, and ease of separation. The catalytic efficiency of the nanocatalyst rose dramatically when the complex was covalently grafted onto the graphene oxide surface, which might be due to the chemical alteration of the graphene oxide sheets. The findings demonstrate that the synthesized nanocatalyst may be reused four times with great chemical stability and minimal reduction in its activity as a catalyst. In addition, Gram-positive and Gram-negative bacteria responded well to the synthesized nanostructure as an antibacterial agent.