Synthesis and characterization of some metal complexes derived from azo compound of 4,4′-methylenedianiline and antipyrine: Evaluation of their biological activity on some land snail species

Abstract

A novel series of metal complexes of the azo dye; bis-(1,5-dimethyl-4-[(E)-(3-methylphenyl)diazenyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) derived from 4,4′-methylenedianiline and antipyrine was synthesized and characterized by different spectral, thermal and analytical methods. The tetradentate ligand reacts with the metal ions as a half unit. All complexes display an octahedral geometry, except Pd(II) complex (7) which has a square planar one. The thermal studies reveal that the complexes have higher thermal stability comparable with that of the free ligand. The activation thermodynamic parameters, such as activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*) and Gibbs free energy (ΔG*) have been calculated using DTG curves. The ESR spectra of the solid Cu(II) complexes showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The biological activities of the ligand, as well as its metal complexes have been tested in vitro against two land snail species; Eobania vermiculata and Monacha obstructa. The results show that all the tested compounds have significant biological activities against the two tested land snail species with different sensitivity levels.