Multi-component Theoretical Assessment of the Corrosion Inhibitory Performance of some Macrocyclic Polyethers Containing 1,3,4 Thiadiazole on the Iron Surface

The adsorption capability of the series of some Macrocyclic Polyether compounds containing 1, 3, 4-thiadiazole entity n-MCTH (n = 1-5), especially 3-MCTH, 4-MCTH and 5 MCTH, and their protonated forms, was studied in the light of DFT quantum modeling and Monte Carlo dynamics calculations.Sensitivity to corrosion has been quantified using the degree of planarity, global and local electronic proprieties, as well as the inhibitor strength of interaction, in neutral and protonated forms, with the (111) iron surface in the metallic complex.The results of both approaches showed the supremacy of the interactions of neutral and proton variants of the 5-MCTH-Fe complexes, compared to their homologues of 3-MCTH-Fe and 4-MCTH-Fe, due to the significant involvement of aryl rings, in addition to the thiadiazole ring, in the process of electron donation and acceptance.