V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane and manganese(II), cobalt(II) and copper(II) complexes: Synthesis, crystal structure, DNA-binding properties and antioxidant activities

•Three new transition metal complexes with V-shaped bis-benzimidazole thioether have been synthesized and characterized.•The ligand and its complexes bind to DNA in an intercalation mode and the order of the binding affinity is bebt > 3 > 2 > 1.•The Cu(II) complex has the preferable ability to scavenge hydroxyl radical and superoxide radical.

A V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane (bebt) and its transition metal complexes, [Mn(bebt)(pic)2]·CH3OH (pic = picrate) 1, [Co(bebt)2](pic)22 and [Cu(bebt)2](pic)2·2DMF 3, have been synthesized and characterized. The coordinate forms of complexes 1 and 2 are basically alike, which can be described as six-coordinated distorted octahedron. The geometric structure around Cu(II) atom can be described as distorted tetrahedral in complex 3. The DNA-binding properties of the ligand bebt and complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that bebt and complexes bind to DNA via an intercalative binding mode and the order of the binding affinity is 1 < 2 < 3 < bebt. The possible relations between the structure and DNA-binding properties are also discussed. Moreover, the complex 3 possess significant antioxidant activity against superoxide and hydroxyl radicals, and the scavenging effects of it are stronger than standard mannitol and vitamin C.

Graphical abstractThree new transition metal complexes have been synthesized and characterized systematically. The ligand and its complexes bind to DNA in an intercalation mode. The Cu(II) complex has a strong potential to be applied as scavengers to eliminate the radicals.Figure optionsDownload full-size imageDownload as PowerPoint slide