Chitosan is a natural, nontoxic biopolymer with amine and hydroxyl functional groups which make it easy for chitosan molecules to form intermolecular and intramolecular hydrogen bonds. In that context, the present study reports Cu(II) supported on Chitosan@LDH@Fe3O4 magnetic nanocomposite (Fe3O4@MgCuAl-LDH@CS/Cu(II)) as an effective and a novel heterogeneous catalyst to perform electrophilic substitution reaction between indoles and aromatic aldehydes to yield bis(indolyl)methane derivatives (BIMs) in shorter reaction time under ultrasonic conditions. Copper ions were mainly adsorbed onto the core-shell magnetic nanocomposite (Fe3O4@LDH) modified with chitosan by the chelating capacity of chitosan and LDH. The catalyst's physicochemical properties and morphological structure were characterized using advanced analytical techniques, including XRD, FT-IR, FESEM, HRTEM, TGA, VSM, and EDX. Overall, the results show that Sonication significantly enhanced the catalytic performances compared to conventional heating. Also, the prepared catalyst could be easily separated from the solution using an external magnetic field and reused up to nine times without considerable leaching or loss in its catalytic activity.
