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.