DNA binding and in vitro anticancer activity of 2‐((1H‐benzimidazol‐2‐yl)methylamino)acetic acid and its copper(II) mixed‐polypyridyl complexes: Synthesis and crystal structure

New copper(II) ternary complexes formulated as [Cu(N‐N)BIG]ClO4, where BIG is deprotonated 2‐((1H‐benzimidazol‐2‐yl)methylamino)acetic acid and N‐N represents 2,2′‐bipyridine (1) or 4,4′‐dimethyl‐2,2′‐bipyridine (2) or 5,5′‐dimethyl‐2,2′‐bipyridine (3) or 1,10‐phenanthroline (4) or 4,5‐diazafluoren‐9‐one (5) or dipyridylamine (6), were synthesized and characterized using analytical and spectral methods. Complex 1 was characterized using single‐crystal X‐ray diffraction analysis and found to be monomeric in nature with distorted square pyramidal geometry. The binding interactions of 1–6 with calf thymus DNA were studied using UV–visible absorption and emission spectroscopy and viscosity measurements. The DNA cleavage ability of 1–6 with pUC19 DNA shows that the complexes can cleave DNA without any external agents. The ligand and complexes were investigated for their in vitro antibacterial activity against Bacillus subtilis and Staphylococcus aureus. The complexes showed enhanced antibacterial activities compared to the free ligand. Molecular docking studies of complexes 1–6 were made using Genetic Optimization of Ligand Docking (GOLD) software. The study indicated that LEU23, ASP25, ILE84, ASN144 and ARG87 of COX‐2 were important for strong hydrogen bonding interaction with the complexes. Among the complexes, 2 showed the best docking result with COX‐2. Cytotoxicity assay was performed using MTT reagent against human cervical cancer cells, human breast cancer cells and human lung cancer cells. The complexes were found to show moderate anticancer activity. The complex [Cu(BIG)(bpy)]ClO4⋅2H2O was structurally characterized using single‐crystal X‐ray diffraction. It crystallizes in the monoclinic space group P21/n with four molecules per unit cell. An asymmetric unit of the complex contains complex molecule, perchlorate anion and two water molecules. The copper ion is coordinated to two nitrogen atoms (N1, N2) and carboxylate oxygen atom (O2) of the tridentate primary ligand BIGH and two nitrogen atoms (N4, N5) of bipyridine.