Mild steel, copper, and aluminum alloy 2024-T3 remain indispensable in industrial applications, from aerospace structures to marine equipment, owing to their mechanical and physical properties. Mild steel offers high tensile and impact strength alongside favorable magnetic characteristics. Copper, with its purplish-red luster, demonstrates excellent castability, wear resistance, and notable corrosion resistance. Aluminum alloy 2024-T3 combines low density with high ductility, thermal conductivity, and resistance to heat and radiation. Yet, exposure to aggressive environments, particularly acidic media, accelerates corrosion, leading to economic losses and safety risks across sectors such as shipping, mining, and manufacturing.
Corrosion occurs when thermodynamic conditions favor metal oxidation, with kinetics dictating the rate of degradation. Protective coatings and chemical inhibitors are widely employed to mitigate this process. Organic inhibitors, especially heterocyclic compounds containing nitrogen, sulfur, and oxygen, have proven effective by adsorbing onto metal surfaces, blocking active sites from corrosive agents. Among these, imidazole and thiazole derivatives have drawn significant attention for their ability to safeguard metals in acidic solutions.
Imidazole derivatives have demonstrated strong anticorrosion performance for mild steel in hydrochloric acid, with electrochemical impedance spectroscopy (EIS) studies showing efficiencies up to 84.3% at 6.5 mM concentration, exhibiting mixed-type inhibition with predominant cathodic action, as reported by He et al. Thiazole compounds have achieved approximately 90% inhibition efficiency for copper at 2 mM in similar conditions, according to Farahati et al., forming protective layers over the metal surface. For aluminum alloy 2024, thiazole derivatives facilitate the formation of thin aluminum oxide films, effectively preventing acid-induced degradation.
Imidazothiazoles, combining structural features of both imidazole and thiazole rings, are well known in pharmaceutical chemistry for their antitumor, antibacterial, anticancer, anti-inflammatory, and anthelmintic properties. Leveraging these molecular attributes for corrosion protection offers a promising avenue. In the present study, a novel imidazothiazole derivative, (E)-1-(4-methoxyphenyl)-3-(6-phenylimidazo[2,1-b]thiazol-5-yl)prop-2-en-1-one (IMT), was synthesized with a yield of 74%. The compound’s corrosion inhibition performance was evaluated for mild steel, copper, and aluminum alloy 2024-T3 in 1 M hydrochloric acid.
Electrochemical techniques, including potentiodynamic polarization (PDP) and EIS, were employed alongside surface characterization by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). Computational methods—density functional theory (DFT) and molecular dynamics (MD) simulations—were used to elucidate the adsorption behavior of IMT on metallic surfaces. The study’s novelty lies in assessing the inhibitor’s performance across three distinct metals, each with different electrochemical and microstructural properties.
Open circuit potential (OCP) measurements indicated minimal changes over time after IMT addition, suggesting stable electrochemical conditions prior to polarization testing. For mild steel and copper electrodes, steady-state OCP was achieved within 30 minutes, while aluminum required approximately one hour. This stability is critical for ensuring reproducible electrochemical data.
EIS results revealed significant increases in charge transfer resistance (Rct) upon IMT addition, indicative of reduced corrosion rates. The inhibitor’s efficiency peaked at a concentration of 10⁻⁴ M, with values following the sequence: copper (96.9%) > mild steel (95.4%) > aluminum alloy 2024-T3 (91.0%). These high efficiencies reflect strong adsorption of IMT molecules onto the metal surfaces, forming barrier layers that impede both anodic and cathodic reactions.
Surface analysis confirmed the presence of protective films on all tested metals. SEM images showed smoother surfaces in the presence of IMT compared to the rough, pitted morphology observed in uninhibited samples. EDX spectra detected characteristic peaks corresponding to IMT’s constituent elements, supporting the adsorption mechanism inferred from electrochemical data.
The combination of imidazole and thiazole functionalities within the IMT molecule appears to enhance its affinity for diverse metallic substrates, likely due to synergistic interactions between heteroatoms and π-electron systems with surface atoms. This structural design enables broad-spectrum corrosion protection, relevant for industries where multiple metals coexist in acidic environments, such as aerospace fuel systems, automotive cooling circuits, and chemical processing equipment.