Density Functional Theory (DFT) modeling and Monte Carlo simulation assessment of inhibition performance of some carbohydrazide Schiff bases for steel corrosion

• The inhibition performance of three Schiff bases on steel were studied theoretically.
• The adsorption energies of the Schiff bases with Fe (110) were high and negative.
• BDTC adsorbed more stronger on Fe than BMTC and BHTC.
• DFT modeling and Monte Carlo simulations provided molecular level insights.
• Theoreical evaluation and experimental results were in good agreement.

DFT and Monte Carlo simulation were performed on three Schiff bases namely, 4-(4-bromophenyl)-N′-(4-methoxybenzylidene)thiazole-2-carbohydrazide (BMTC), 4-(4-bromophenyl)-N′-(2,4-dimethoxybenzylidene)thiazole-2-carbohydrazide (BDTC), 4-(4-bromophenyl)-N′-(4-hydroxybenzylidene)thiazole-2-carbohydrazide (BHTC) recently studied as corrosion inhibitor for steel in acid medium. Electronic parameters relevant to their inhibition activity such as EHOMO, ELUMO, Energy gap (ΔE), hardness (η  ), softness (σσ), the absolute electronegativity (χ), proton affinity (PA)(PA) and nucleophilicity (ω) etc., were computed and discussed. Monte Carlo simulations were applied to search for the most stable configuration and adsorption energies for the interaction of the inhibitors with Fe (110) surface. The theoretical data obtained are in most cases in agreement with experimental results.

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