Divalent transition metal complexes of multidentate nitrogen, oxygen and sulfur containing ligand: Design, spectroscopic, theoretical molecular modeling and antioxidant like activity

Abstract

A novel thiosemicarbazide, 2,2'- (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbonyl) bis (N-allyl hydrazine-1-carbothioamide) (TSc) (1) was prepared and characterized by elemental analysis, IR, 1 H, 13 CNMR, electronic and mass measurements. Metal complexes (2-4) were also prepared by reacting with acetate salts of Co 2+ , Ni 2+ and Cu 2+ ions and characterized by elemental, spectral (IR, UV-vis., ESR (for Cu 2+ ), mass, molar conductivity and magnetic moments measurements. IR data indicated the TSc chelates, as neutral ON in the mononuclear Co (II) complex, binegative O2N2S2 hexadentate in binuclear Ni (II) and Cu (II) complexes or as mononegative ON neutral chelate in keto-thione form binding one Zn atom from one arm and in enol-thione form binding the other Zn atom in the second arm). Zn 2+ complex afforded a tetrahedral geometry while other complexes assigned an octahedral environment. The thermal degradation was studied to establish the thermal stability of the title compounds and the kinetic parameters were evaluated. Also, DFT method was used to draw the geometry of all compounds and the parameters such as bond lengths, bond angles, dipole moment, Frontier orbitals (HOMO, LUMO), MEP and other energetic parameters (optical energy gap, softness, hardness, electronegativity) were evaluated. Furthermore, the compounds were screened for DNA binding as well as SOD antioxidant activities.