Arginine-functionalized magnetic Stachys schtschegleevii trichome-supported Cu(II) nanocomposite for the recyclable synthesis of γ-lactams

A plant-derived magnetic nanocomposite, Cu@Fe 3 O 4 - SSC -Arg, was prepared in three stages: (i) in situ co-precipitation of Fe 3 O 4 on the surface of Stachys schtschegleevii ( SSC ) trichomes; (ii) covalent functionalization of the magnetized trichomes with L-arginine to introduce carboxyl, primary amine, and guanidinium coordination sites; and (iii) immobilization of Cu (II) ions on the arginine-modified support. FT-IR, XRD, FE-SEM, TEM, VSM, ICP, EDS, elemental mapping, and TGA were used to investigate the structural and physicochemical features of each intermediate and the final material. ICP analysis indicated a Cu loading of 0.76 mmol.g − 1 , and TEM/FE-SEM gave average particle sizes of ≈ 27 and ≈ 31 nm, respectively. The catalytic activity of Cu@Fe 3 O 4 - SSC -Arg was evaluated in the three-component condensation of a series of substituted aromatic amines and aromatic aldehydes with ethyl pyruvate, delivering γ-lactam derivatives in 81–98% isolated yield in ethanol at room temperature within 20 min. The catalyst was magnetically recovered and reused for seven consecutive runs without significant loss of activity, and FT-IR, XRD, and FE-SEM confirmed its structural integrity after reaction. The combination of the plant-derived support, the arginine functionality, and the immobilized Cu (II) provides a recyclable catalytic platform for γ-lactam synthesis under mild conditions.