Synthesis, crystal structure and biological activity of two binuclear Ag(I) complexes with bis-benzimidazole thioether ligands

Two new binuclear Ag(I) complexes of the types, [Ag-2(bbt)(2)](pic)(2)center dot 2DMF 1 and [Ag-2(bmbt)(2) (p-coumarate)(2)]center dot 2CH(3)OH 2 (bbt = 1,3- bis(2-benzimidazyl)-2-thiapropane; bmbt = 1,3-bis(1-methylbenzimidazol-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. Structural analysis show that coordination environment of complexes 1-2 are both a binuclear metallacycle with 2-fold rotational symmetry and can be described as a distorted tetrahedral geometry. In addition, there is strong Ag-Ag interaction in the complex 1. The salient structural feature of 2 is that one of two oxygen atoms of carboxylate group of p-coumarate adopts a monodentate bridging mode to connect two Ag(I) ions. In order to explore the relationship between the structure and biological properties, DNA binding propensity have also been studied. The results suggested that the two ligands and the two Ag(I) complexes bind to DNA via intercalative binding mode, and the order of the binding affinity is 1 > 2 > bbt > bmbt. Moreover, we also discovered that the complex 2 possesses significant antioxidant activity against superoxide and hydroxyl radicals. (C) 2017 Elsevier B.V. All rights reserved.