Copper(II) complexes containing derivative of aminobenzoic acid and nitrogen-rich ligands: Synthesis, characterization and cytotoxic potential
Ginikachukwu Grace Nnabuike, Sunita Salunke‐Gawali, Archana S. Patil, Ray J. Butcher, Joshua A. Obaleye, Harsha Ashtekar, Bharathi Prakash
Abstract
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···O, C-H···O, C H···π, and π···π. 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.