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This study aims to explore the inhibitory action of certain derivatives of Schiff's base, namely 4-(pyridin-2-ylimino) pentan-2-one (CE5),4-(pyrimidin-2-ylimino) pentan-2-one (CE4) and 4-((1H-tetrazol-5-yl) imino) pentan-2-one (CE20) against mild steel (MS) corrosion in 1 M HCl by the gravimetric, stationary and transient method. For additional information on the inhibitory properties of the studied compounds, scanning electron microscopy (SEM) and functional density theory (DFT) calculations were also performed. The effectiveness of the Schiff's base derivatives studied follows the order: CE20 > CE4 > CE5. The electrochemical impedance curves show that the corrosion reaction is controlled by a charge transfer process, while the potentiodynamic polarization curves indicate that the synthesized compounds act as a mixed-type inhibitor. The adsorption process follows the Langmuir isotherm. Kinetic, as well as thermodynamic parameters, were calculated and discussed. The increase in EHOMO and decrease in gap energy ΔEgap lead to an increase in the inhibition efficiency. Results obtained from quantum chemical studies are in good agreement with quantum chemical parameters and experimental inhibition efficiencies. [ABSTRACT FROM AUTHOR]

[Display omitted] • SAP1, SAP2, and SAP3 performance towards the corrosion inhibition for mild steel in 1 M HCl using weight loss, EIS and PP measurements revealed excellent results. • The inhibition efficiency showed a slight decrease with the rise of temperature. • The surface characterization SEM/EDX justified the adsorption of SAP molecules on mild steel surface. • Quantum chemical calculations and Monte Carlo simulation confirmed the experimentally obtained results. Controlling corrosion of metals and their alloys in acidic environments has recently received increasing scientific attention. Therefore, our study investigated three newly synthesized Schiff base (imine) derivatives, namely (3Z,3'Z)-4,4′-(ethane-1,2-diyldiimino)bispent-3-en-2-one (SAP1), (4′E)-4,4′-(pyridine-2,6-diyldinitrilo)dipentan-2-one (SAP2), and (4′E)-4,4′-(benzene-1,3-diyldinitrilo)dipentan-2-one (SAP3) to understand their adsorption on mild steel (MS) surface effects in 1 M HCl solution using electrochemical and theoretical methods. The obtained results show that the three inhibitors have good protective effects. Electrochemical techniques show that the presence of these compounds significantly increases the polarization resistance and influences both the anodic and cathodic reactions. This means that these inhibitors have mixed properties. The stability of these molecules at higher temperatures, from 298 K up to 328 K, was examined by polarization potentiodynamic measurements. This study revealed that these compounds resist temperature by adsorbing on the MS surface to form a protective barrier. Scanning electron microscopy with Energy Dispersive X-ray Analysis (SEM-EDX) was also implemented to understand the adsorption phenomenon. In addition, density functional theory (DFT) and Monte Carlo simulation (MC) were performed to confirm the experimental results. [ABSTRACT FROM AUTHOR]