Copper(II) complexes containing derivative of aminobenzoic acid and nitrogen-rich ligands: Synthesis, characterization and cytotoxic potential

Four mixed ligand copper(II) complexes bearing mefenamic acid and different heterocyclic nitrogen donor ligands have been synthesized. A direct one-step metal-ligand complexation method was adopted in synthesizing the complexes. These newly formed complexes are [Cu(mef) 2 (imi) 2 ]; CM-1 , [Cu(mef) 2 (py) 2 ]; CM-2 , [Cu 2 (mef) 4 (apy) 2 ].2CH 3 CN; CM-3 , and [Cu(mef) 2 (nic) 2 (C 2 H 5 OH)]; CM-4 (mef = mefenamato, imi = imidazole, py = pyridine, apy = 2-aminopyridine, and nic = nicotinamide). The complexes were characterized by both analytical and spectral methods. FTIR studies confirmed the mefenamato ligand coordinated via a deprotonated carboxylato oxygen atom to the Cu(II) center. The molecular structures of CM-1 and CM-2 showed both are isostructural and exhibit square-planar geometry around Cu(II). CM-3 crystallized in the dimeric form, each Cu(II) is in five-coordinate geometry, with a structural paddle wheel motif. The resulting square pyramidal geometry in CM-4 is due to the ethanol solvent's coordination on the pyramid's axial position. The crystal lattice of the complexes was stabilized by noncovalent interactions such as N-H center dot center dot center dot O, C-H center dot center dot center dot O, C -H center dot center dot center dot pi, and pi center dot center dot center dot pi. The mononuclear complexes were more stable than the dimeric complex CM-3, revealed by thermogravimetric analysis. In addition, the cytotoxic study of the copper (II) complexes on lung carcinoma cells (NCIH-460) and breast cells (MDAMB) were evaluated using MTT dye (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay.(c) 2023 Elsevier B.V. All rights reserved.