Structural elucidation, molecular modeling, and biological and antioxidant studies of phenanthroline/nicotinamide metals complexes

Abstract

Three new cobalt (II), nickel (II), and copper (II) complexes [M (nicotinamide)(phenanthroline)(H2O)3]Cl2·3H2O (where M: Co (II), Ni (II) and Cu (II)) have been prepared and characterized by elemental analysis, Fourier transform infrared (FT‐IR), and ultraviolet/visible (UV–Vis) spectroscopy as well as thermal analysis. The molar conductance measurements proved that the complexes were electrolytes. The results obtained from FT‐IR confirm that the metal atoms were coordinated by one nitrogen atom from nicotinamide (NA) ligand, two nitrogen atoms from phenanthroline (Phen), and three oxygen atoms from three different water molecules. The complexes have octahedral structure. thermogravimetry (TGA) and its differential (DTG) analyses confirmed the suggested stereochemistry. Coats–Redfern and Horowitz–Metzger equations were used to calculate kinetic and thermodynamic parameters. Molecular modeling calculations confirm the structural geometry of the complexes, and the data indicate that the complexes are soft with respect to ligands where absolute softness (σ) varied from 5.34 to 13.33 eV, whereas σ for NA and Phen are 5.34 and 8.19 eV, respectively. The ligands and their complexes were assayed for their in vitro antimicrobial activities against some bacterial and fungal strains; the data showed that the complexes were active against some bacterial species compared with NA and Phen. Moreover, complexes and ligands revealed excellent antioxidant properties and could be useful in fighting the free radicals which occur in close connection with cancerous cells.