Synthesis and anticorrosive activity of two new imidazo[1, 2-a]pyridine Schiff bases

[Display omitted] •Synthesis of new Schiff bases based on imidazo[1, 2-a]pyridine.•Characterization of the synthesized ligands by different spectroscopic methods such as: NMR, MS, IR and melting point.•Valorization of these products as corrosion inhibitors.•Combination of AFM and SEM observations of the steel surface.•DFT and Molecular dynamics simulation studies to validate the experimental results. In the present work, the synthesis of two new imidazo[1, 2-a]pyridine derivatives belonging to the schiff base family was performed. They are named respectively : (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(thiophen-2-yl)methanimine (IP1) and (E)-N-(7-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(5-nitrothiophen-2-yl)methanimine (IP2). The ligands were synthesized from a condensation reaction between 2-phenylimidazo[1,2-a]pyridin-3-amine and a commercial aldehyde (2-thiphencarbaldehyde for IP1 and 5-Nitro-2-thiophencarbaldehyde for IP2 in the presence of a catalytic amount of acetic acid in diethyl ether). The structures of the titrated compounds were determined using various spectroscopic techniques such as 1H NMR, 13C NMR, FT-IR and MS. However, the synthetic ligands showed very good inhibitory efficacy against corrosion of mild steel in 1 M HCl medium. This was evaluated by various electrochemical techniques such as mass loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results showed that the inhibitory efficiency of the synthesized ligands improves with the increase of concentration to reach the maximum value of 91% for IP1 and 96% for IP2 for a concentration of 10−3M, which translates that the surface covered by the inhibitor increases with the concentration. In addition, quantum chemical calculation based on density functional theory (DFT) confirmed the existence of good correlations between experimental and predicted spectroscopic data. Surface analysis carried out by SEM and AFM showed a smooth surface in the presence of the ligands IP1 and IP2.