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Crystal structure, Spectroscopic Studies, DFT Calculations, Cyclic Voltammetry and Catalytic Activity of a Copper Schiff Base Complex
1  Faculty of Technology, Ferhat Abbas University, Setif 19137, Algeria.
Academic Editor: Blaž Likozar


Herein, we describe the synthesis of a novel tetradentate Schiff base ligand, H2L, with a diaminotoluene spacer, and its corresponding mononuclear copper complex, CuL, in methanol solvent. The characterization of all new compounds was conducted using various spectroscopic techniques, such as FT-IR, UV-vis, 1H, 13C, 1H-1H COSY-NMR and MS. Single-crystal X-ray diffraction analysis of the CuL complex revealed a monoclinic system with a Cc space group, comprising four molecules per unit cell. Conductivity measurements indicated the nonelectrolytic nature of the complex, while the electrochemical behavior exhibited a quasi-reversible redox process. Quantum calculations, performed using DFT and TD-DFT theory at the M062X/6-311**G/ SDD level, demonstrated good agreement with the experimental data. Notably, the copper compound displayed larger static and dynamic hyperpolarizability values compared to urea, suggesting potential as an excellent second- and third-order nonlinear optical (NLO) material.

Furthermore, the prepared complex effectively catalyzed the homogeneous oxidation reaction of cyclohexene in the presence of H2O2 as an oxidant, achieving a high conversion rate of 98% with CuL as the catalyst. The bromoperoxidase activity was explored in the oxidative bromination of phenol red as a trap, employing the studied complex which can be considered as a potential functional model of bromoperoxidase, with the reaction rate constant k equal to 2.203 × 105 (mol L-1)-2s-1.

Keywords: Complex, X-ray diffraction, Electrochemical, Cyclohexene oxidation, Bromoperoxydase activity, DFT.