Enhanced anti-corrosive properties of thiabendazoles: A computational study

Abstract In this work, various strategies, including introduction of functional groups (Cl, Br, OH, NH2, OCH3 and SH) with different electronic nature, aliphatic chains of varying length, and aza, oxa, and carbonylation substitutions to thiabendazole (TBZ), were employed to design novel thiabendazole derivatives, and to search for potential new inhibitors with higher inhibition efficiency. To this end, the geometries, frontier molecular orbital energies (EHOMO and ELUMO, energy gap), global electrophilicity index, nucleophilicity index, absolute electronegativity, absolute hardness, softness, fraction of electrons transferred and Fukui functions of 24 TBZ derivatives were investigated by the density functional theory method. The results showed that the strategies outlined above have significant effects on the anti-corrosive properties. Most of the designed TBZ derivatives are large, planar and conjugated molecules, and the introduced groups can improve the electronic delocalization through the p-π and π-π interactions. The OH, NH2 and OCH3 groups can improve the electron donating ability significantly. Aza, oxa and combination of oxa and carbonylation substitutions can greatly enhance the feedback bonding. The long alkyl chain can increase the electron donating ability to some degree, but also lead to decreased feedback bonding. In all, 18 TBZ derivatives are predicted to have better adsorption properties than TBZ and, therefore, improved inhibition efficiencies.