Synthesis and evaluation of copper(II) complexes for peroxidase-mimicking activity

This study delineates the synthesis and characterization of three novel copper(II) complexes, denoted as [Cu(L1)2] 1, [Cu(L2)2] 2 and [Cu(L3)2] 3, originating from Schiff base ligands HL1 I, HL2 II and HL3 III. These ligands were produced by condensation, in an equal ratio, of salicylaldehyde, o-vanillin, and 3,5-Di-tert-butylsalicylaldehyde with 4-chlorobenzylamine in methanol. The comprehensive characterization of these complexes employed various techniques, with particular emphasis on single-crystal X-ray diffraction studies for ligand I, and complexes 1, and 2, revealing a square planar geometry for the copper atom bischelated by donor atoms from the ligands. Theoretical studies were conducted to optimize the geometry of ligand I and complexes 1 and 2. These theoretical findings were consistent with experimental results, including frequency and nuclear magnetic resonance investigations. Beyond structural elucidation, the peroxidase-like action of these complexes was examined by assessing their catalytic ability in the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in the presence of hydrogen peroxide(H2O2). The reported results contribute to a holistic understanding of the structural and functional aspects of these copper(II) complexes, bridging experimental evidence with theoretical insights.