In this study, benzimidazolylmethyl-pyrazole carboxylate derivatives were synthesized via a 1,3-dipolar cycloaddition reaction and characterized using IR, HRMS and NMR spectroscopy. Three derivatives, namely ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1-phenyl-1H-pyrazole-3-carboxylate (Ph-BPC), ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro- 1H-benzo[d]imidazol-1-yl)methyl)-1-(p-tolyl)-1H-pyrazole-3-carboxylate (CH3Ph-BPC), and ethyl 1-(4-chlorophenyl)-5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1H-pyrazole-3-carboxylate (ClPh-BPC), were evaluated as corrosion inhibitors for mild steel (MS) in a 1 M HCl solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements revealed high inhibition efficiencies of 98.5 %, 98.2 %, and 97.7 % for ClPh-BPC, Ph-BPC, and CH3Ph-BPC, respectively, at a concentration of 10-4 M. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed the formation of protective surface layers, significantly reducing corrosion rates. Thermodynamic analysis indicated that the adsorption of these inhibitors follows the Langmuir isotherm model with adsorption energies of −50.12 kJ/mol for ClPh-BPC, −50.52 kJ/mol for Ph-BPC, and −51.62 kJ/mol for CH3Ph-BPC, suggesting chemisorption. Computational studies, including Monte Carlo (MC), density functional theory (DFT), and molecular dynamics (MD) simulations, showed strong agreement with experimental results, further validating the adsorption behavior and corrosion inhibition mechanisms of these compounds.
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