Corrosion inhibition performance of organic compounds and theoretical calculations based on density functional theory (DFT)

Abstract 2,5-Bis(4-dimethylaminophenyl)-1,3,4-oxadiazole (DAPO), 2-acetylthiophene thiosemicarbazone (2-AT), 2-hydroxyphenyl-5-mercapto-1-oxa-3,4-diazole (HMO), and 2-cinnamyl-5-mercapto-1-oxa-3,4-diazole (CMO) have been studied by measurement several quantum chemical parameters such as E HOMO , E LUMO , bandgap energy, softness, hardness, electrophilicity, nucleophilicity, and Fukui function analysis. The best corrosion inhibition efficiency was evaluated through a comparison between theoretical and experimental results. In gas and aqueous phases, protonated and nonprotonated species were investigated for their electronic structures in order to discover the factors and reasons behind corrosion inhibition. A theoretical study of all the studied compounds in gas and aqueous phases was investigated by employing the density functional theory (DFT) at 6–311++G(d, p) basis set and Becke’s three parameters hybrid exchange–correlation functional (B3LYP). The molecules are calculated using quantum computational chemistry calculations such as Gaussian09 software. The experiments were carried out on carbon steel and HCL. Carbon steel is the most often used steel because it combines outstanding mechanical qualities with a low cost. One of the most commonly utilized agents for these purposes is HCl solution. On the other hand, steel and ferrous alloys are likely to corrode under certain conditions. One of the most effective strategies for protecting metals against corrosion is corrosion inhibitors, and they are becoming more common.