A theoretical study on the inhibition efficiencies of leucine and isoleucine as corrosion inhibitors of vanadium

Vanadium is a light transition metal having various metallurgical applications and shows active behavior and anodic dissolution[2].The semi-empirical computational methods have been used most successfully in finding correlation between theoretically calculated properties and experimentally determined inhibition efficiency for uniform corrosion[1]. There is no doubt that the recent progress in DFT has provided a very useful tool for understanding molecular properties and for describing the behavior of atoms in molecules. Quantum chemical calculations using the density functional theory (DFT) and AM1 and PM3 semi-empirical methods were performed on two amino acids namely leucine(Leu) and isoleucine(Ile) used as corrosion inhibitors for Vanadium. The quantum chemical parameters including EHOMO, ELUMO, difference between them (ELUMO-EHOMO) , dipole moment ( μ ) and electronic charges were obtained. Calculations at the DFT level were performed using sto-3g basis sets. The negative sign of the EHOMO values indicates that the data obtained support physical adsorption mechanism[3]. A good correlation was observed in comparison of theoretical and experimental results confirming the reliability of employed method.