Synthesis, characterization, crystal structure and DNA-binding studies of two zinc(II) complexes with the V-shaped bis(benzimidazole)-thiapropane and its derivative ligand

Two novel zinc(II) complexes [Zn(bbt)2](pic)2·DMF·2CH3OH (1) and [Zn(et-bbt)(acrylate)2] (2) (bbt = 1,3-bis(2-benzimidazyl)-2-thiapropane; et-bbt = 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane; pic = picrate) have been synthesized and characterized by elemental analysis, electrical conductivities, IR, UV–Vis spectral measurements and X-ray single crystal diffraction. The crystal structures of two Zn(II) complexes were four-coordinated forming a distorted tetrahedral geometry. Interactions of the complexes with calf thymus DNA (CT-DNA) were investigated by spectrophotometric methods and viscosity measurements. The experimental results suggest the complexes bind to DNA in an intercalation, and DNA-binding affinity of the complex 1 is stronger than that of the complex 2. Furthermore, the possible relations between the structure and DNA-binding properties have been discussed.

Graphical abstractTwo V-shaped ligands and their novel four-coordinated Zn(II) complexes have been synthesized and characterized. Their DNA binding properties were investigated systematically. The change of electron density and V-shaped angle may be the reasons to explain the DNA-binding affinity of the complexes.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Two bis(benzimidazole)-thiapropane Zn(II) complexes have been synthesized. ► Two Zn(II) complexes bind to CT-DNA in an intercalation mode. ► The possible relations between structure and DNA-binding properties are discussed.