Aromaticity of Heterocyclic Compounds and Their Corrosion Inhibition Property: Experimental and Theoretical Analysis

Abstract

Heterocycle derived moieties, namely, <i>N</i>-(4-methoxyphenyl)-1-(1<i>H</i>-pyrrol-2-yl)methanimine (MPM), 1-(furan-2-yl)-<i>N</i>-(4-methoxyphenyl)methanimine (FMM), and <i>N</i>-(4-methoxyphenyl)-1-(thiophen-2-yl)methanimine (MTM), were synthesized followed by analysis of their structural aspects using FTIR and ¹H NMR spectroscopic techniques. The corrosion retarding abilities of the same were distinguished by gravimetric and certain electrochemical measures for mild steel in 0.5 M H₂SO₄, and MTM was obtained with maximum inhibition efficiency of 97.93% at 250 mg L^-1 concentration; the thermodynamic and activation parameters were recorded in this regard. The results were further seen to be supported by various surface studies: SEM-EDS, XPS, AFM, contact angle, and UV-visible spectroscopy. Potentiodynamic polarization studies unveiled the mixed nature of heterocyclic inhibitors with overriding anodic effect. Furthermore, the adsorption of inhibitors over mild steel coupons demarcates the prevalence of physical and chemical interactions in the environment. In addition, the computational studies, global and local reactivity, molecular dynamics, and density functional theory, were employed and the experimental results obtained were found in correlation with the theoretical results.