Synthesis, Characterization, and Corrosion Inhibition Activity of New Imidazo[1.2-A]pyridine Chalcones

In this work, two new Imidazo[1.2-a]pyridine chalcones (IMZs) namely, 1-(3-methylpyrazin-2-yl)-3-(2-phenylimidazo[1,2-a]pyridin-3-yl)prop-2-en-1-one (IMZ1) and 3-(2-(4-chlorophenyl)imidazo[1,2-a]pyridin-3-yl)-1-(3methylpyridin-2-yl)prop-2-en-1-one (IMZ2) were synthesized and characterized by spectroscopic methods namely, High Performance Liquid Chromatography (HPLC) coupled to Mass Spectrometry (MS) and NMR Nuclear Magnetic Resonance (1H and 13C) and investigated as corrosion inhibitors for mild steel (MS). The study included surface morphology, electrochemistry, gravimetric, theoretical, and computational analyses.Electrochemical results (Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization (PDP)) demonstrate that IMZs are effective MS inhibitors in 1 M HCl. PDP studies demonstrated Imidazo[1,2-a]pyiridine chalcones at the ideal 1 mM concentration decreased the icorr from 0.948 mA/cm2 (blank) to 0.069 mA/cm2 and 0.051 mA/cm2 for IMZ1 and IMZ2, respectively, with the assistance of a mixed type inhibitor with cathodic predominance. Similarly, the maximal efficiencies of IMZ1 and IMZ2 ligands were 92.43 and 95.40 percent, respectively. Langmuir isotherm and adsorption thermodynamics investigation indicated that the chosen inhibitors adsorb on the metal surface by forming covalent bonds with adsorption constants on the order of 104 M-1. The potential sites for molecule adsorption on the metal surface were identified by theoretical and computational studies, offering new knowledge about the corrosion prevention process.