Comprehensive evaluation of a benzimidazole-1,3,4-oxadiazole derivative for corrosion protection of C38 steel in HCl: Experimental, molecular dynamics, monte carlo, and in silico pharmacokinetic approaches

In this study, 2-methyl-5-(2-methyl-1H-benzimidazol-5-yl)-1,3,4-oxadiazole, a novel heterocyclic compound derived from 1,3,4-oxadiazole, is synthesised and thoroughly characterised. Mass spectrometry, FTIR-ATR spectroscopy, ¹H-NMR, and ¹³C-NMR were used for structural elucidation. This compound's ability to inhibit corrosion in C38 steel in 1 M hydrochloric acid was examined using both stationary (potentiodynamic polarisation) and non-stationary (electrochemical impedance spectroscopy, EIS) electrochemical techniques. The inhibitor considerably decreased the corrosion current density, as shown by the Tafel polarisation curves, and its effectiveness improved with increasing concentration. Nyquist plots supported these results by showing that charge transfer resistance increased with immersion time, indicating stable surface adsorption and efficient protection. Monte Carlo (MC) and Molecular Dynamics (MD) simulations were performed on the Fe(110) surface in the presence of a simulated acidic aqueous environment in order to obtain molecular-level understanding of the inhibitor's adsorption behaviour. These simulations supported the high inhibition efficiency observed in experiments by confirming strong adsorption energies and stable conformations of the inhibitor on the metallic surface. Moreover, molecular docking studies revealed the compound's multi-target binding affinities, which frequently outperformed reference ligands and indicated the possibility of wider biological applications. Although hepatotoxicity was noted as a possible concern that required additional biological validation, in silico ADME and toxicity profiling showed generally positive pharmacokinetic properties. This multidisciplinary strategy, which combines computational modelling, pharmacological profiling, and experimental electrochemistry, highlights the potential of this benzimidazole–oxadiazole derivative as a dual-purpose corrosion inhibitor and bioactive candidate.