Structure, DNA binding and cleavage of a new Zn(II)Mn(II) macrocyclic complex

A new heterodinuclear complex of an unsymmetrical macrocycle [ZnMnL(CH3O)2]·H2O has been synthesized by the cyclocondensation between N,N′-bis(3-formyl-5-chlorosalicylidene)ethylenediimine and 2-hydroxyl-1,3-propanediamine in the presence of the metal ions, and characterized by elemental analyses, IR spectra and X-ray determination. The interactions of the complex with DNA have been investigated by UV absorption, fluorescence spectroscopy, viscosity measurements and electrochemical studies. Absorption spectroscopic investigation reveals that the complex has good binding propensity to calf thymus DNA by intercalation with a binding constant of 2.52 × 105 M−1. Fluorescence spectroscopy shows that the complex can displace ethidium bromide and bind to DNA, with a quenching constant of 4.37 × 103 M−1. The agarose gel electrophoresis studies show that pBR322 plasmid DNA can be transformed to nicked form and linear form in air by the complex.

The approximately planar structure of the title complex makes it easier to intercalate into the base pairs in DNA helix; and has higher binding and cleavage activity.Figure optionsDownload as PowerPoint slideHighlights
► A new heterodinuclear complex has been synthesized and fully characterized.
► The complex binds to DNA with higher binding constant.
► The complex can cleavage DNA in lower concentration.