Synthesis, structure, DNA-binding properties and antioxidant activity of silver(i) complexes containing V-shaped bis-benzimidazole ligands

Abstract

A V-shaped ligand bis(2-benzimidazol-2-ylmethyl)benzylamine L(1) with its two derivatives bis(N-methylbenzimidazol-2-ylmethyl)benzylamine L(2) and bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine L(3) have been prepared. Reaction of these shape-specific designed ligands with Ag(pic) (pic = picrate) afforded three novel complexes, namely, [Ag(2)L(1)(2)](pic)(2)1, [Ag(2)L(2)(2)](pic)(2)·2DMF 2 and [AgL(3)(pic)] 3. The ligands and complexes were characterized on the basis of elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. Complex 1 is a dinuclear metallacycle with a 2-fold rotational symmetry in which two syn-conformational L(1) ligands are connected by two linearly coordinated Ag(I) atoms. Due to the strong interaction between two adjacent Ag(I) atoms, the coordination mode of the central Ag(I) atom can be described as T-shaped. Complex 2 consists of a centrosymmetric dinuclear pore canal structure assembled from two nearly linearly coordinated Ag(I) atoms and two L(2) ligands. The structure of complex 3 adopts a four-coordinate environment for AgN(2)O(2), with the counterion participating in an eight-shaped geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurements, electronic absorption, and fluorescence. The results suggest that the ligands and complexes bind to DNA in an intercalation mode, and their binding affinities for DNA are also different. Moreover, the three Ag(I) complexes also exhibited potential antioxidant properties in vitro studies.

Synthesis and crystal structure determination of copper(II)-complex: In vitro DNA and HSA binding, pBR322 plasmid cleavage, cell imaging and cytotoxic studies

“…When the DNA helix was intercalated by planar molecules such as by classical intercalator EB, base pairs are separated to accommodate the binding molecule, resulting in the lengthening of the DNA helix and subsequently increased DNA viscosity. On contrary complexes bound to DNA through groove binding do not alter the relative viscosity of DNA whereas complexes that bound electrostatically will produce bend or kink the DNA helix, reducing its effective length and its viscosity, concomitantly [23]. On addition of increasing amount of complex 1, the relative viscosity of CT DNA decreases which was comparable with the known intercalator ethidium bromide (EB) (which shows significant increase in relative viscosity) (Fig.…”

A New Isoindoline Based Schiff Base Derivative as Cu(II) Chemosensor: Synthesis, Photophysical, DNA Binding and Molecular Docking Studies

“…11. Intercalative binding of small molecules into DNA base pairs leads to elongation and/or rigidification of the double helix, which resulted in a significant increment in DNA viscosity while partial and/or non-classical intercalation trend to bend or kink of the DNA helix, resulting reduction in its effective length, thereby decrease in viscosity [39]. As illustrated in the Fig.…”

Crystal structure, DNA-binding properties and antioxidative activities of a novel silver(I) inorganic polymer

“…A complex bond to DNA through intercalation is characterized by hypochromism in absorbance, due to the intercalation mode involving a strong stacking interaction between the aromatic chromophore and the DNA base pairs. The obvious hypochromism and bathochromism shift are usually characterized by the non-covalent intercalative binding of a compound to the DNA helix, due to the strong stacking interaction between the aromatic chromophore of the compound and base pairs of DNA [33][34][35][36]. To compare quantitatively the affinity of the Ag(I) complex toward DNA, the intrinsic binding constants K b of the two compounds to CT-DNA were determined by monitoring the changes of absorbance with an increasing concentration of DNA.…”