Corrosion Inhibitive Potentials of some 2H-1-benzopyran-2-one Derivatives- DFT Calculations

Abstract

There is an increased demand for metals and alloys because of their use in household appliances and industrial machines. However, they react with the environment and are consequently prone to loss of strength and durability owing to corrosion. In a bid to eradicate or control this, the use of corrosion inhibitors has been employed. Quantum chemical calculations have been used to predict the corrosion inhibitive potentials of novel molecules and probe into their metals' surface mode of action. Density functional theory was employed here with a polar basis set, 6-31G(d), to investigate the corrosion inhibitive potentials of some 2H-1- benzopyran-2-ones derivatives via their electronic properties, global reactivity descriptors, electrostatic potential maps, and Fukui indices. The energy gaps follow the order: c > e > a > d > b > g > f > h, indicative that compounds f and h would effectively protect metals’ surface against corrosion with the HOMO map essentially delocalized over the benzopyran-2-one moiety and the attached substituents while the LUMO plot shows a delocalization of the lowest vacant molecular orbitals over the entire benzopyran-2-one moiety. The asymmetric charge distribution on the inhibitors from the electrostatic potential maps indicates that each compound possesses reactive adsorption sites for bonding and back-bonding with the metal surface. The Mulliken charge distribution and the Fukui indices reveal that the adsorption of an inhibitor on a metal surface is not only via the heteroatoms like O, Cl, Br, and N. The contribution of carbon atoms as nucleophilic and electrophilic centers ensures effective interaction between a metal surface and the inhibitor and isolates the material from corroding environment.