Inhibitory effect of some benzoxazole derivatives on corrosion of mild steel: a computational study

Abstract

Inhibitory effect of five benzoxazole derivatives (Benzoxazole [BZ], 2-methylbenzoxazole [MBZ], 6-Nitro-1,3-benzoxazole [NBZ], 2-benzoxazolethiol [BZT] and 2-phenylbenzoxazole [PBZ]) on corrosion of mild steel were theoretically evaluated using Density Functional Theory (DFT) method in gas phase. Quantum chemical parameters such as highest occupied molecular orbital energy (E(HOMO)), lowest unoccupied molecular orbital energy (E(LUMO)), energy gap (?E), global hardness (?), global softness (?), polarizability (?), dipole moment (?), ionization potential (I), electron affirnity (A), electronegativity (?), and fraction of electron transferred (?N), were calculated at the B3LYP level of theory with 6-31G* basis set. PBZ showed the highest inhibitory effect among the five molecules having close agreement with experimental results. The Mullikan charges of the atoms of these molecules were also computed. They revealed that the possible sites of electrophilic attack were on the nitrogen and oxygen atoms, which had greater negative charges. The electronic structures as well as reactivity of these molecules and other parameters could be used in designing novel, high-efficient, cheap, and eco-friendly inhibitors.