Unprecedented formation of a μ‐oxobridged dimeric copper (II) complex: Evaluation of structural, spectroscopic, and electronic properties by using theoretical studies and investigations biological activity studies of new Schiff bases derived from pyrazolone

Abstract

Novel Schiff base Cu (II) complex was synthesized in the present work through condensation of salicylaldehyde with 4‐aminoantipyrine derivative and characterized by spectral and analytical techniques. Crystal structure of the Cu (II) complex was determined by single‐crystal X‐ray diffraction technique. The structure of the complex is quite unexpected and unprecedented. The observation can be due to the in situ oxidation of the methyl groups of the 4‐aminoantipyrine of the Schiff base ligand to CH2OH. Cu2L2 is a two‐centered Ci‐symmetry complex that is bridged by two oxygen atoms from two ligand molecules, with four‐coordinated Cu (II) ion's in a very regular square‐planar fashion. The electrochemical properties of complex in DMSO displayed the electronic effects on the groups on redox potential. Various computational studies such as DFT (density functional theory), MEPs (molecular electrostatic potential), and HS (Hirshfeld surface analysis) were performed to understand the properties of different interactions of the compounds. The DFT computations, geometry optimization of the ligand, and Cu (II) complex (1) were optimized using the B3LYP method with (6‐311G) basis set. Also, HS analysis is used for decoding intermolecular interactions in the crystal system and contribution of component units for the construction of the 3D architecture. Anticancer effects of the ligand and complex in MTT assay against cancer cell lines SW480 were studied. The antioxidant activity results show that the ligand and complex have antioxidant and anticancer activity. Molecular docking study was also carried out for the complex to find its binding affinity to protein B‐cell lymphorna (BCL‐2, PDB ID: 4LXD).