Utility of Quantum Chemical Parameters in the Rationalization of Corrosion Inhibition Efficiency of Some Organic Inhibitors

Quantum chemical parameters were calculated for inhibitor compounds like substituted pyridines, anilines, guanides, azoles, oxadiazoles, diols, and diamines. The degree of corrosion inhibition has been correlated with the energy of the highest occupied molecular orbital (E_HOMO), E_LUMO–E_HOMO, the degree of softness of the inhibitor, :, the chemical potential, ΔN, the fraction of charge transferred from the inhibitor to the metal, and ΔH, the heat of reaction in the case of iron, aluminum, copper, and zinc. The calculated quantum chemical parameters of inhibitor molecules are useful in predicting the corrosion inhibition performance of the inhibitors leading to a rational method of the selection of inhibitors.