Investigation of 3‐(phenylsulfinyl)indoles self‐assembled monolayer for the inhibition of iron corrosion in acidic media

Abstract 3‐(phenylsulfinyl)indoles have been synthesized by the direct sulfoxide reaction of 1 H ‐indoles with benzenesulfenamide in water as a green reaction medium. The corrosion inhibition effects and the hydrophobicity of the self‐assembled films were explored by electrochemical methods and surface analysis methods. The results show that the self‐assembled film mainly inhibits the cathodic process of the iron electrode. After the iron electrode was assembled in 5 mM 3‐(p‐tolylsulfinyl)‐1 H ‐indole/3‐((4‐fluorophenyl)sulfinyl)‐1H‐indole ethanol solutions for 9 h, the corrosion inhibition efficiencies in 1.0 M HCl solution reached 91.50% and 94.24%, respectively. The surface morphology of the self‐assembled film on iron exposed to the test solution was examined using scanning electron microscopy and the chemical composition of the corrosion inhibition surface was analyzed by X‐ray photoelectron spectroscopy. In the quantum chemical calculation part of this study, the active adsorption sites on the metal surface are located in the indole‐sulfoxide framework, forming feedback bonds and coordination bonds with an iron atom.