Synthesis, experimental, theoretical, and molecular dynamic studies of 1-(2,5-dimethoxy-4-methylphenyl)ethan-1-thiosemicarbazone as green inhibitor for carbon steel corrosion.

• Synthesis and spectroscopic characterizations of new 1-(2,5-dimethoxy-4-methylphenyl)ethan-1-thiosemicarbazone molecules. • With an optimal dose (1.5 mM) the efficiency of inhibition reached 96% at 298 K in 1 M HCl. • Polarization measurements indicate that compound 4 exhibits a mixed-type corrosion inhibition mechanism. • The adsorption of compound 4 on the iron surface was demonstrated by DFT calculations as well as the dynamic Monte Carlo simulations. • Theoretical data provide an in-depth understanding of the experimental results. In this report, a thiosemicarbazone, namely, 1-(2,5-dimethoxy-4-methylphenyl) ethan-1-thiosemicarbazone 4 was synthesized from naturally occurring para methoxy-thymol and investigated as a new corrosion inhibitor on carbon steel in 1 M HCl solution, using combined experimental and theoretical explorations. Weight loss, potentiodynamic polarization (PDP), impedance spectroscopy (EIS), and Scanning Electron Microscopy (SEM) were used to research the inhibition performance and determine the adsorption distribution characteristics of compound 4. The obtained results revealed that this obtained molecule has a high corrosion inhibitory power for carbon steel in 1M HCl and its inhibition efficacy reaches a value of 96% at 1.5 mM compound 4. The results further revealed that compound 4 functions as an effective mixed-type inhibitor. Density function theory (DFT) and molecular dynamics simulations were also adopted to provide a robust representation of corrosion phenomena in realistic conditions. The structure synthesized was confirmed by NMR (1H & 13C), IR, and high-resolution mass spectroscopy (HRMS). [ABSTRACT FROM AUTHOR]