New Theoretical Insights about Anticorrosive Effects and Adsorption Mechanism of Some α-Amino Acids on Al Surface: DFT, MEP, FMO, NBO, QSAR, Fukui Functions and Monte Carlo Simulation

Six amino acids were studied for their corrosion inhibition properties, taking into account the experimental results. The computed quantum chemical descriptors gave almost the same trend in high precision, and this matching reveals the reliability of computational calculations in this field of research. The reactivity of the investigated amino acids was found to be in the order; tryptophan > methionine > proline > leucine > valine > alanine, where alanine showed the lowest inhibition efficiency while the tryptophan showed the highest efficiency and that may be due to its π system which enables to donate π electrons to the metal surface or accept through antibonding π* character through back donation process. QSAR also gave the same expectations with high correlation with the experimental results. Also, The Monte Carlo simulation predicted the best adsorption mode for the investigated compounds which looks planner on the metal surface.