Structure–activity relationship and adsorption behavior of a thiazole-derived Schiff base corrosion inhibitor for mild steel: integrated experimental and theoretical study

The corrosion of mild steel in acidic environments remains a critical challenge across various industrial sectors. In this work, a novel thiazole-derived Schiff base inhibitor was synthesized via a mild ethanol-assisted condensation method and comprehensively evaluated for its anticorrosion performance in 1 M HCl. The molecular design incorporates multiple active centers (–OH, C = N, N, S) and a conjugated π-system to promote surface adsorption. Weight loss measurements revealed a maximum inhibition efficiency of 91.2% at 1000 ppm, while electrochemical studies (OCP, EIS, and PDP) confirmed the formation of a protective barrier that significantly reduced corrosion current density. Surface analyses (SEM/EDS and XPS) indicated reduced surface degradation and strong nitrogen–metal interactions, affirming inhibitor adsorption. Temperature-dependent studies showed increased activation energy upon inhibitor addition. Quantum chemical (DFT) and molecular dynamics (MD) simulations supported the experimental results, revealing a stable parallel adsorption geometry on Fe(110) and a high adsorption energy (–273 kcal/mol). Comparative analysis with reported thiazole-based inhibitors highlights the superior performance of the synthesized compound. The integrated experimental–computational strategy provides new insights into structure–activity relationships and offers a promising, eco-conscious inhibitor for industrial corrosion protection.