Computational assessment of structure-activity relationship, adsorption behaviour and significance on corrosion inhibition of some benzothiazole-based compounds

Adsorption of organic compounds on surfaces plays a decisive role in corrosion inhibition, especially on steel materials. The interaction of the sites on the organic molecule with the active sites on the surface remains a complex phenomenon that is very challenging to explain from purely experimental investigation. The integration of computational intelligence through computer algorithms and softwares reduces the laborious and time consuming trial and error stages of laboratory experiments. In this study, density functional theory was deployed to expound the adsorption of benzothiazole and four of its derivatives, namely: benzothiazol-2-ol (BZT-OH), benzothiazol-2-amine (BZT-NH2), benzothiazol-2-carboxylic acid (BZT-COOH) and benzothiazol-2-thiol (BZT-SH) on Fe(110) surface. Energy and quantum chemical calculations were performed to determine the positions and orientations of molecular orbitals, molecular reactivity, most preferable sites for nucleophilic and electrophilic attack as well as potential adsorption sites. Molecular dynamics simulation were performed to understand the configuration of the adsorbed molecules on the surface and to predict the mechanism of adsorption. Results reveal that the adsorption sites were mostly domiciled around N, O and S atoms of the amine, carboxyl/hydroxyl and thiol groups, respectively. Adsorption energy decreased following the trend BTZ-COOH > BTZ-SH > BTZ-NH2 > BTZ > BTZ-OH whereas binding energy decreased following the trend BTZ-SH > BTZ-COOH > BTZ-OH > BTZ-NH2 > BTZ. Overall, adsorption of BTZ-COOH and BTZ-SH respectively was most enhanced and strongest on Fe(110) surface. All the studied molecules would exhibit good adsorption characteristics on steel surface, making them potential efficient ingredients for formulation of corrosion inhibitors.