Synthesis, molecular structure, supramolecular and biological evaluation of benzimidazole-based Schiff bases
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Updated: Oct 31, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Mohammed Enamullah1,2, Imdadul Haque1, Taslima Akter3
1Department of Chemistry, Jahangirnagar University Dhaka 1342 Bangladesh enamullah@juniv.edu.
Abstract:
Benzimidazole-based Schiff bases, (Z)-2-(((1H-benzo[d]imidazol-2-yl)imino)methyl)phenol monohydrate (HL1·H2O) and (Z)-1-(((1H-benzo[d]imidazol-2-yl)imino)methyl)naphthalen-2-ol monohydrate (HL2·H2O) were synthesized and characterized by IR, UV-vis, EI-mass, 1H NMR spectroscopy, and single-crystal X-ray diffraction studies. Molecular structure determination suggested the presence of crystal water in the unit cell of each compound. The structure adopted a usual enol-imine form, with an intramolecular hydrogen bond between the phenolate-oxygen and the imine-nitrogen atoms. Supramolecular packing indicated that the structure was assembled and stabilized by several significant intermolecular non-covalent interactions between symmetrically related lattice water and the molecules, as supported by quantitative Hirshfeld surface analyses. DSC analyses revealed an irreversible phase transition from solid-crystal to isotropic liquid. Computational modeling by DFT/TD-DFT supported the experimental results of the molecular and electronic structures of the compounds. Molecular orbital (MO) calculations revealed a relatively lower HOMO-LUMO energy gap for HL2 (ΔE g = 2.41 eV) compared with HL1 (2.65 eV), suggesting the former had enhanced charge delocalization due to the extended π-electrons conjugation system, in parallel with molecular electrostatic potential (MEP) surface maps. Biological activities were assessed using cytotoxicity, antioxidant, α-amylase, and antibacterial tests. HL1 possessed more pronounced cytotoxic effects on cervical cancer (HeLa) cells (IC50 = 75.53 ± 3.10 µM) than HL2 (IC50 = 462.61 ± 5.24 µM). DPPH radical-scavenging studies revealed moderate antioxidant activity for HL2 (IC50 = 168 ± 4 µM) and weaker activity for HL1 (IC50 = 233 ± 5 µM) compared with the standard ascorbic acid (IC50 = 106 ± 1 µM). HL1 showed moderately the inhibit α-amylase enzyme (IC50 = 399 ± 2.7 µM), while no inhibitory activity for HL2 was noted. Both compounds were moderately active against selected bacterial strains in a concentration-dependent manner. Computational analyses on Escherichia coli BepA metalloprotease (6SAR) and human DNA topoisomerase IIα (5GWK) using molecular docking exhibited favorable predicted protein-ligand interactions, involving hydrogen-bonding, hydrophobic and π-stacking interactions. HL1 had a more favorable predicted binding affinity towards BepA metalloprotease, whereas HL2 had a more favorable predicted binding affinity towards human DNA topoisomerase IIα, which was associated with enhanced hydrophobic interactions.
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