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

Abstract

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 salicylaldehyde 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 (L-2), respectively. Two kinds of copper(II) and nickel(II) complexes with different ligands were prepared. Reaction of H2L1 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 {(MN2O2)-N-II} 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 {(MN2N2)-N-II} 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(L-2)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.