Sangaré Kassoum^1,, Coulibaly Bamoro¹, Seyhi Brahima², Diomandé Sekou¹, Yao-Kouassi Akoua Philomène³

The aim of the current study was to perform Density Functional Theory calculations in order to investigate the corrosion inhibition capabilities of selected molecules on metal surfaces. The study focused on five 2-[(benzimidazolyl)methylthio]imidazole derivatives as potential corrosion inhibitors. Geometric optimization studies of the molecules was performed using the B3LYP/6-31+G(d,p) level of theory. Subsequently, several electronic properties, such as Frontier Molecular Orbital (FMO) energies (HUMO, LUMO), energy band gap (ΔE), dipole moment (μD), electronegativity (χ), softness (S), chemical hardness (η) and fraction of electrons transferred to the metal surface (ΔN) were analyzed. The FMO analysis provides information on the electron donation and backdonation processes occurring between the inhibitors and the metal surfaces. Based on Gibbs free energy (ΔG) calculation, all studied molecules exhibited thermodynamic stability (ΔG < 0). Among them, 1-BZ-H and 2-BZ-CH₃ showed the highest E_HOMO energies and ∆N values, indicating strong electron-donating abilities and efficient adsorption on the metal. In contrast, 3-BZ-NO₂ showed the smallest band gap and largest dipole moment, reflecting its high reactivity due to electron backdonation and polarization effects. The molecules 4-BZ-Cl and 5-BZ-CF₃ showed moderate inhibitory activity, which is in accordance with their intermediate electronic properties.

corrosion inhibitors, nitrogen–sulfur heterocycles, DFT calculation, electron transfer