Synthesis, crystal structure, DNA-binding properties and antioxidant activity of zinc(II) complexes based on the V-shaped bis(2-benzimidazol-2-ylmethyl)benzylamine ligand and its derivative

Two V-shaped ligands, bis(2-benzimidazol-2-ylmethyl)benzylamine (L1) and its derivative bis(N-allylbenzimidazol-2-ylmethyl)benzylamine (L2) have been prepared. Reaction of two shaped-specific designed ligands with Zn(pic)2 (pic = picrate) afforded two novel complexes, namely, [ZnL12](pic)2·2MeCN·Et2O 1, and [ZnL22](pic)2 2. The ligands and Zn(II) complexes were characterized by elemental analysis, UV–Vis, IR spectroscopy. Single crystal X-ray diffraction revealed that two Zn(II) complexes have similar distorted octahedral coordination geometry, except that the degree of distortion is different. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurement, electronic absorption and fluorescence titration. The results suggested that the ligands and Zn(II) complexes bind to DNA via intercalative binding mode, and their binding affinity for DNA are also different. Moreover, two Zn(II) complexes also exhibited potential antioxidant properties in vitro studies, and the complex 1 reveal more effective than complex 2.