Synthesis and characterization of bis(azine) ligands and metal complexes: DNA-interaction and extraction properties for metals and dichromate anions

Two new bis(bidentate) azine ligands were prepared by linking (1Z ,1^ Z)-1,1^ -{butane-1,4-diylbis[oxybenzene- 4,1-diyl(1Z)eth-1-yl-1-ylidene]}dihydrazine to alicylaldehyde and pyridine-2-carbaldehyde, 1,4-bis{4- {(1E) -1-((2E) -(2-hydroxybenzene–2-ylmethy-lidene)hydrazonylidene)ethyl}phenoxy}butane (H2L1), and 1,4-bis{4-{(1E) -1-((2E) -(pyridine–2-ylmethylidene)hydrazonylidene)ethyl}phenoxy}butane (L2), respectively. Two kinds of copper(II) and nickel(II) complexes with different ligands were prepared. Reaction of H2 L1 with Cu(II) and Ni(II) acetate with 1:1 molar ratio gave double stranded binuclear bis(azine) complexes with stoichiometry [M(L^1)] 2 containing {MII N2O2 } centers. On the other hand, 1:1 molar ratio reaction of Cu(II) and Ni(II) chloride with L^2 yielded mononuclear metal complexes with general stoichiometry [M(L^2)Cl 2 ] containing {M^II N2N2 } centers. The structures of both bis(azine) ligands and complexes were identified by elemental analysis, infrared spectra, UV–Vis electronic absorption spectra, magnetic susceptibility measurements, and TGA. DNA binding and DNA cleavage activities of the mononuclear complexes of L^2 , [M(L^2)Cl 2 ] were examined by using UV-Vis titration and agarose gel electrophoresis, respectively. The results indicate that mononuclear complexes, especially [Cu(L2)Cl 2 ], bind significantly calf thymus DNA and cleaves pBR322 DNA. Furthermore, the complexing properties of the bis-azine ligands toward selected transition metal cations and dichromate anions were also reported. It was found that bis(azine) ligands have high extraction ability towards dichromate anions.