Synthesis, Characterization and DNA Binding study of Heteroleptic Metal(II) Complexes of Benzylacetone-benzoylhydrazone Mixed with N,N-Donor Ligands

In this study, benzylacetone-benzoylhydrazone ligand (BABH) and its heteroleptic metal(II) complexes [Co(II), Ni(II) and Cu(II)] with 2, 2´-bipyridine, 1, 10-phenanthroline, and ethylenediamine (N-N donors) were synthesized. The compounds were analysed with spectroscopic techniques (Infrared; IR, Ultraviolet-Visible; UV-Vis, 1H NMR), percentage metal analysis, magnetic moment measurement and conductivity measurements. The Calf-thymus-DNA interaction with the complexes was examined using electronic absorption spectroscopy. The 1H NMR indicated the formation of BABH. Infrared spectra indicated that BABH coordinated to the metal ions in enol form via the deprotonated carbonyl group and the azomethine group, while N-N donor ligands bound through the pyridinic nitrogen atoms. The UV-Vis spectra of the compounds had intra-ligand transitions due to π-π* and n-π* in the UV region, and d-d transitions typical for Cu(II), Ni(II) and Co(II) ions in the visible region. Molar conductivity of the complexes in DMF indicated a 1:1 electrolyte, except [Cu(BABH)(phen)(H2O)Cl] with a value of 50.20 (Ω-1cm2mol-1) which suggested a non-electrolyte. The percentage metal analysis revealed a stoichiometry ratio of 1:1:1 (Metal: Ligand: N,N-donor), except for the bipyridine complexes that had a probable 1:1:2 ratio (Metal: Ligand: N,N-donor). The magnetic moment for Cu(II) complexes ranges from 1.80 - 2.34 B.M indicating octahedral geometry, while Ni(II) complexes had values ranging from 2.88 to 3.28 B.M indicating octahedral geometry, except [Ni(BABH)(en)]Cl.H2O that had a value of 0.89 B.M. which indicated a square palanar nickel(II) complex. Co(II) complexes had values for octahedral geometry (3.77 - 4.81 B.M), except [Co(BABH)(en)]Cl.H2O that had a 1.96 B.M, revealing a square planar geometry. Interactions of the synthesized compounds with CT-DNA represents an intercalative binding mode, with [Co(BABH)(bpy)2]Cl.H2O having the best binding strength of 6.74 x 104 M-1. The results have shown that the synthesised metal(II) complexes of Benzylacetone-benzoylhydrazone mixed with N,N-donors has potential ability to disrupt the growth of tumour cells due to their good binding strength.