(E)-1-((((1H-benzo[d]imidazol-2-yl)methyl)imino)methyl)naphthalen-2-ol, ligand was synthesized by condensation of (1H-benzo[d]imidazol-2-yl) methanamine, with 2-hydroxynaphthaldehyde. The ligand and the metal complexes were characterized by various spectroscopic techniques. Interpretation of spectra confirmed that the ligand adopted either a neutral tridentate or a monobasic tridentate mode, bonded to the metal ions through the nitrogen atom of the heterocyclic benzimidazole, azomethine nitrogen atom and deprotonated phenolic oxygen atom forming either a square planer geometry. X-ray powder diffraction analysis of complexes indicated that the complexes were crystalline in nature with triclinic structures. The antibacterial and the antifungal activities of the ligand and its complexes were examined against Escherichia coli , Bacillus subtilis and Aspergillus niger by well- diffusion method. The results showed that Cd (II) complex exhibits the highest antifungal and antibacterial activities among the tested complexes. The in vitro antitumor activityies of the different complexes were tested and the results revealed an important cytotoxicity of cadmium complex against MCF-7, Hep G2 and HCT 116 cell. Iron complex showed also a strong toxicity towards Hep G2 and HCT cell whereas moderate activity against MCF-7. The bioassay study of different complexes against mosquito larvae demonstrated strong activity of zirconium complex with 0.172 values of LC50.

Benzimidazole, a fused bicyclic compound with benzene and pentacyclic 1,3-diazole moeities, has a simple aromatic heterocyclic structure. The moiety has become an indispensable anchor for the development of new pharmacologically active products, and has yielded several therapeutic agents with anticancer, antihypertensive, antimicrobial, antifungal and antiulcer effects. Benzimidazoles, as synthetically feasible and pharmacophoric synthons, have been relentlessly pursued for the preparation of new analogues and derivatives, and they have successfully developed into some of the most sought-after and vital pharmacophores for drug discovery. The use of varied substituents and differing patterns around the benzimidazole nucleus has provided a wide spectrum of biological activities. In addition, the benzimidazole moiety constitutes a building block for the production of several drugs, drug candidates, new chemical entities, and lead molecules. The importance of this nucleus for bioactivity, e.g., antibacterial, antitubercular, antidiabetic, anticancer, antifungal, anti-inflammatory, analgesic, antioxidant, antihistaminic, and antimalarial activity, has led us to take note and provide an overview of the synthetic development approaches for various benzimidazole derivatives together with their biological actions. This review is projected to further assist in the design and development of new benzimidazole-based compounds for new and optimized pharmacologically active products towards new drug-development strategies.

A novel series of benzimidazole ureas 3a–h were elaborated using 2-(1H-benzoimidazol-2-yl) aniline 1 and the appropriate isocyanates 2a–h. The antioxidant and possible antidiabetic activities of the target benzimidazole-ureas 3a–h were evaluated. Almost all compounds 3a–h displayed strong to moderate antioxidant activities. When tested using the three antioxidant techniques, TAC, FRAP, and MCA, compounds 3b and 3c exhibited marked activity. The most active antioxidant compound in this family was compound 3g, which had excellent activity using four different methods: TAC, FRAP, DPPH-SA, and MCA. In vitro antidiabetic assays against α-amylase and α-glucosidase enzymes revealed that the majority of the compounds tested had good to moderate activity. The most favorable results were obtained with compounds 3c, 3e, and 3g, and analysis revealed that compounds 3c (IC₅₀ = 18.65 ± 0.23 μM), 3e (IC₅₀ = 20.7 ± 0.06 μM), and 3g (IC₅₀ = 22.33 ± 0.12 μM) had good α-amylase inhibitory potential comparable to standard acarbose (IC₅₀ = 14.21 ± 0.06 μM). Furthermore, the inhibitory effect of 3c (IC₅₀ = 17.47 ± 0.03 μM), 3e (IC₅₀ = 21.97 ± 0.19 μM), and 3g (IC₅₀ = 23.01 ± 0.12 μM) on α-glucosidase was also comparable to acarbose (IC₅₀ = 15.41 ± 0.32 μM). According to in silico molecular docking studies, compounds 3a–h had considerable affinity for the active sites of human lysosomal acid α-glucosidase (HLAG) and pancreatic α-amylase (HPA), indicating that the majority of the examined compounds had potential anti-hyperglycemic action.

Throughout this research, a unique optical sensor for detecting one of the most dangerous heavy metal ions, Cu(II), was designed and developed. The (4-mercaptophenyl) iminomethylphenyl naphthalenyl carbamate (MNC) sensor probe was effectively prepared. The Schiff base of the sensor shows a “turn-off” state with excellent sensitivity to Cu(II) ions. This innovative fluorescent chemosensor possesses distinctive optical features with a substantial Stocks shift (about 114 nm). In addition, MNC has remarkable selectivity for Cu(II) relative to other cations. Density functional theory (DFT) and the time-dependent DFT (TDDFT) theoretical calculations were performed to examine Cu(II) chelation structures and associated electronic properties in solution, and the results indicate that the luminescence quenching in this complex is due to ICT. Chelation-quenched fluorescence is responsible for the internal charge transfer (ICT)-based selectivity of the MNC sensing molecule for Cu(II) ions. In a 1:9 (v/v) DMSO-HEPES buffer (20 mM, pH = 7.4) solution, Fluorescence and UV-Vis absorption of the MNC probe and Cu(II) ions were investigated. By utilizing a solution containing several metal ions, the interference of other metal ions was studied. This MNC molecule has outstanding selectivity and sensitivity, as well as a low LOD (1.45 nM). Consequently, these distinctive properties enable it to find the copper metal ions across an actual narrow dynamic range (0–1.2 M Cu(II)). The reversibility of the sensor was obtained by employing an EDTA as a powerful chelating agent.