Spectroscopic investigation, thermal, molecular structure, antimicrobial and anticancer activity with modelling studies of some metal complexes derived from isatin Schiff base ligand

Abstract

Condensation reaction between isatin drug and 2,6-diaminopyridine in a 1:1 M ratio, has been applied to prepare a tridentate Schiff base ligand (L). A series of metal complexes Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) have been synthesized. Prepared compounds were characterized by elemental analyses, IR, 1H NMR, UV–visible, solid reflectance, molar conductivity, mass spectroscopy, X-ray diffraction, scanning electron microscope, TGA and DTG. From the analytical data, (metal:ligand) ratio was found to be 1:1 with tetrahedral geometry except for Cr(III), Fe(III), Cd(II) and Cu(II) complexes which have an octahedral geometry. All complexes are electrolytes except Fe(III) and Cd(II) complexes are nonelectrolytes. The IR spectra suggested that the ligand is coordinated to the metal ions in a neutral tridentate manner. 1H NMR spectra confirm the participation of the amino group in coordination. In vitro antimicrobial activities for (L) and its complexes were performed. Fe(III), Cu(II) and Cd(II) complexes showed the highest antibacterial activity against S. aureus (G+ bacteria). While, Co(II) and Cd(II) complexes were the most active complexes against B. subtilis. Cd(II) and Ni(II) complexes also recorded the highest activity against G- Salmonella species and E. coli, respectively. The results presented the equity of Ni(II) and Zn(II) antifungal activity against C. albicans. The cytotoxicity of the prepared compounds was experienced against breast cancer (MCF-7 cells viability). The results revealed that Mn(II) complex have the lowest IC50 value which indicates the highest activity rather than the other compounds.. To gain insight of the binding mode, the ligand (L) was docked with the active site receptors of (PDB code 3HB5, 6CGD, and 3LD6).