Benzimidazole ligands with allyl, propargyl or allene groups, DNA binding properties, and molecular docking studies

Abstract

Three benzimidazole based tridentate ligands (L1–L3) and their mononuclear complexes with the general formula of [M(L)Cl2] (where M: Mn(II), Cu(II), and Zn(II), L: ligand) were prepared. The solid state structures of the ligands and [Cu(L1)Cl2], [Mn(L3)Cl2], and [Zn(L3)Cl2] complexes were determined by single crystal X‐ray diffraction studies. The X‐ray crystallographic data confirmed the tautomeric conversion of alkyne groups in L2 to allene isomer L3. In the structures of the complexes, each metal ion is five‐coordinate binding to three nitrogen atoms from the ligands and two chloride ions. The ligands and their metal complexes were studied for their DNA binding properties (Dsfs‐DNA, double‐stranded fish sperm DNA). DNA binding studies were performed by UV–Vis and fluorescence techniques and experimental observations revealed strong binding of ligands and order of DNA binding was found to be L2 > L3 > L1. The DNA binding ability of the metal complexes is higher than free ligands. Finally, molecular dockings were performed to investigate the possible interaction sites of the DNA with the synthesized molecules. Molecular dockings results showed that the ligands bind into the minor groove of DNA.

Synthesis, characterization and investigation of photophysical and biological properties of Cu(II) and Zn(II) complexes of benzimidazole ligands

“…The compound showed considerable binding affinities towards DNA, and their binding affinities are lower than those of standard DNA intercalating ( K b value of spermine and ethidium bromide are 2.1 × 10 5 and 8.1 × 10 4 M −1 , respectively) agents. [ 23 ] The UV–Vis spectral changes and binding constants ( K b ) suggest that the ligands and their Cu(II) and Zn(II) complexes interact with DNA in groove binding mode. [ 40 ] The ligand L 1 showed the highest binding properties with K b of 10 × 10 4 M −1 , and complexation of L 1 with Cu(II) and Zn(II) decreased the binding affinity of the free ligand.…”

“…It is informative to compare the DNA binding properties of the ligands with the similar ligands with different N‐substitute groups (allyl, propargyl or allene groups) reported by our group. [ 23 ] It was observed that the substitute groups on the 2,6‐bis(2‐benzimidazole)pyridine moiety as well as complexation of the ligands with different metal ions have affected the DNA binding properties. Moreover, the planarity of the pyridine and two side benzimidazole units also has an impact in the DNA binding affinities.…”

“…Accordingly, when compared the binding energies of other compounds after DNB (À12.8 kcal mol À1 ), L 1 ligand has the best binding energy (À8.2 kcal mol À1 ) The results showed compatibility with the literature. [23,[41][42][43]…”

“…[21] In our previous work, we found that the planarity of the benzimidazole ligands and substitute groups are important factors for DNA binding properties. [22,23] Moreover, the geometry around the metal centre also plays an important role for DNA-ligand interactions. In continuance of our interest in DNA binding properties of 2,6-bis(benzimidazole)pyridine compounds, herein, we prepared two benzimidazole based ligands (Figure 1) and their Cu(II) and Zn(II) complexes.…”

Synthesis, antimicrobial potential and computational studies of crystalline 4-bromo-2-(1,4,5-triphenyl-1H-imidazole-2-yl)phenol and its metal complexes

“…17,18 Several imidazole derivatives and their metal complexes have also been reported to have promising DNA binding affinities. 19 Recently, quantum-mechanical calculations have been recognized as an important tool for predicting various characteristics like non-covalent interactions, HOMO–LUMO energies, and non-linear optical properties of various classes of compounds. In this context, our research group have reported the synthesis and computational investigations of various classes of compounds such as peptoids, 20 hydrazones, 21,22 chalcones and β-hydroxy carbonyl compounds, 22,23 functionalized esters, 24 piperidone derivatives, 25 functionalized pyrimidines, 26,27 phosphonates, 28 monocarbonyl curcuminoids, 29,30 functionalized indoles, 31 and unsymmetrical acyl thioureas, 32 as well as organic salt systems, 33,34 transition metal complexes, 11 etc.…”