Mononuclear copper(II) complexes with (Z)-N′-{(2-hydroxynapthalen-1-yl}methylene)acetohydrazide: X-ray single-crystal structures, Hirshfeld analysis, X-band epr spectra, DFT calculations and SOD mimetic activity

Abstract

The 1:1 reaction of (Z)-Ń-{(2-hydroxynapthalen-1-yl}methylene)acetohydrazide (HL) and copper(II) salt in methanol yields a series of new mononuclear complexes, [Cu(HL)(OH2)]ClO41, [Cu(HL)(OH2]ClO42, [Cu(HL)(OH2)]NO33 and [Cu(L)(Cl)] 4. The room temperature magnetic moments of the complexes 1–4 are 1.79, 1.78, 1.80 and 1.76B.M. respectively. The absorption bands emerging in the UV region (337–341 nm) are characteristic of the HL ligand. In these complexes, the LMCT bands were observed in the range of 503–506 nm and the d-d band at 617–623 nm. The molecular structures of all four complexes have been solved using single-crystal X-ray analysis. The X-ray analysis shows the formation of supramolecular structures through various non-covalent interactions viz., CH∙∙∙π and π···π intermolecular interactions. The detailed Hirshfeld surface and fingerprint plots yielded a comparative picture of the mode of non-covalent interactions. The DFT calculations were performed and the results are in good agreement with experimental results. X-band epr spectral measurements have been carried out to authenticate the paramagnetic behavior of all complexes. The stability of the copper(II) centre was examined using cyclic and differential pulse voltammetry. The IC50 and SOD activity values for all complexes reveal that they are good models among the best values reported for low molecular weight mononuclear copper(II) complexes.