Anchoring of Cu(II) Schiff Base Complex to the Surface of Graphene Oxide: Access to an Efficient Catalyst for Application in Water Remediation

The development of highly active and selective catalytic systems for chemical transformations has become the main focus of many research directions to address the broad concern of energy and environmental demands. Surface organometallic chemistry (SOMC) is a well-established approach for the design, preparation, and characterization of well-defined single-site catalysts. In this work, we provide a facile approach for grafting the as-prepared Cu(II)-Schiff base complex, [CuL(H₂O)₂OAc], derived from the condensation of 2-aminopyridine with salicylaldehyde, onto the surface of functionalized graphene oxide (FGO) using 3-aminopropyltriethoxysilane (3-APTES), followed by reductive treatment via hydrazine hydrate to afford r[CuLFGO] as a highly efficient, low cost, heterogeneous catalyst. Various analytical techniques, including ¹HNMR, IR, UV-Vis, XRD, SEM, XPS, and Raman spectroscopy have been utilized for the characterization of the prepared Cu(II) Schiff base catalyst. Importantly, the catalytic performance of the reduced form of the catalyst r[CuLFGO] was evaluated using the reduction process of 4-nitrophenol (4-NP), as a model of wastewater contaminant, in the presence of hydrazine hydrate (NH₂.NH₂.H₂O) as a reducing agent under mild reaction conditions. The obtained results showed excellent catalytic activity with ~ 93% conversion. The k_app of the reaction was estimated as 2.02 × 10^− 2 min^− 1 and the catalyst can be recycled many times without major loss of the catalytic activity.