Experimental and theoretical study of new Schiff bases based on Imidazo(1,2-a)pyridine as corrosion inhibitor of mild steel in 1M HCl

Abstract In this work, we report a study on the synthesis and characterization, using several spectroscopic techniques such as IR, 13C NMR, 1H NMR and mass spectroscopy, of a new series of Schiff bases based on imidazo(1,2a)pyridine (IMP) scaffold, and the evaluation of their ability to inhibit the corrosion of mild steel in 1M HCl by mass loss techniques, Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and quantum chemistry calculation based on density functional theory (DFT). The obtained results show that these inhibitors, namely (E)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)-1-(1H-pyrrol-2-yl)methanimine (IMP1), (E)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)-1-(thiophen-2-yl)methanimine (IMP2) and (E)-1-(5-nitrothiophen-2-yl)-N-(2-phenylimidazo(1,2-a)pyridin-3-yl)methanimine (IMP3), act only by reducing the cathode area without changing the mechanism of the cathodic reaction, and that the effectiveness of the inhibition increases with increasing concentration of the inhibitors. The adsorption of the studied compounds on the surface of mild steel follows the Langmuir isotherm model. And finally, we highlighted the existence of a correlation between the molecular structure of the tested inhibitors and their anticorrosion activity.