Synthesis and characterization of quinoxalinone-based heterocycles for corrosion inhibition: electrochemical, spectroscopic, and microscopic studies with theoretical analysis

Purpose This study aims to synthesize two organic heterocyclic compounds, (2E,3E)-6-chloro-2,3-dihydrazinylidene-1-methyl-1,2,3,4-tetrahydroquinoxaline (MR1) and (2E,3E)-2,3-dihydrazinylidene-1-methyl-1,2,3,4-tetrahydroquinoxaline (MR2), characterize them using nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR) and evaluate their effectiveness as corrosion inhibitors in an acidic environment (15% HCl). Design/methodology/approach The synthesized compounds, MR1 and MR2, were tested for their corrosion inhibition properties using potentiodynamic polarization and electrochemical impedance spectroscopy. Post-corrosion, the steel surface was analyzed with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) to confirm the adsorption of the compounds. The experimental findings were further supported by density functional theory calculations and molecular dynamics simulations. Findings The results indicated that both MR1 and MR2 exhibit significant anticorrosive activity in a 15% HCl environment. The analyses performed with SEM, EDX and AFM confirmed the effective adsorption of the inhibitors on the steel surface, forming a protective layer. Theoretical studies provided additional insights into the adsorption mechanisms and stability of the inhibitors. Originality/value This work introduces novel organic heterocyclic compounds based on quinoxalinone as effective corrosion inhibitors in acidic environments. The combined experimental and theoretical approach provides a comprehensive understanding of their anticorrosive behavior.