Regulating the interaction mechanism of thiazole derivatives with mild steel through the conjugation effect: a combined DFT and MD simulation

Abstract

DFT calculations qualitatively and quantitatively reveal that increased charge accumulation at the 2-isobutylthiazole (IBT)/2-acetylthiazole (ACT) with Fe interface strengthens the bonding between heteroatom active sites and Fe atoms. ACT exhibits superior inhibition performance, with adsorption energies of −70.56 kcal/mol⁻¹ for ACT compared to −61.33 kcal/mol⁻¹ for IBT, attributed to its extended conjugation and the strongest FeO bonding energy (−1.08 eV). The interaction originates from π-d hybridization, where enhanced π/π* delocalization promotes orbital overlap with Fe d states, confirming that a parallel molecular orientation is most favorable. MD simulations under acidic conditions further demonstrate that both conjugation and active sites dictate the extent of π-d coupling. Greater surface coverage of ACT leads to a more compact and stable protective film that effectively blocks corrosive species. The results provide atomic level insights into the anticorrosion mechanism, which could help in understanding the organic-metal interface and designing more effective inhibitors.