Three- and four-coordinate Ag(I) complexes of crotonate and bis(benzimidazole)-2-oxapropane ligands: syntheses, crystal structures, DNA-binding studies and antioxidant activities

Two V-shaped ligands, namely 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxapropane (etobb) and 1,3-bis(1-benzylbenzimidazol-2-yl)-2-oxapropane (bobb), have been prepared. Reaction of these ligands with AgNO 3 and sodium crotonate under in the dark afforded the complexes, [Ag(etobb) 2 ](crotonate)·C 2 H 5 OH·2(CH 3 CN)·2(H 2 O) 1 and [Ag(crotonate)(bobb)] 2 . Both complexes have been characterized by physicochemical and spectroscopic methods and also by X-ray single-crystal diffraction. The coordination environment of complex 1 can be described as distorted tetrahedral, while complex 2 has as a trigonal planar geometry. The DNA-binding properties of these complexes have been investigated by fluorescence, electronic absorption and viscosity measurements. The experimental results suggest that they bind to DNA by an intercalation mode. Complex 2 also exhibits excellent hydroxyl radical scavenging activity.