Computational simulation and statistical analysis on the relationship between corrosion inhibition efficiency and molecular structure of some phenanthroline derivatives on mild steel surface

The density functional theory (DFT) at the B3LYP/631G (d) basis set level was performed on three phenanthroline derivatives used as corrosion inhibitors, namely 2-mesityl-1H-imidazo[4,5-f][1,10]phenanthroline (G), 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (J) and 2-(pyridine-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (K) to investigate the correlation between molecular structure and the corresponding inhibition efficiency (I%). The quantum chemical properties most relevant to their potential action as corrosion inhibitors have been calculated in the neutral and protonated forms in aqueous phase for comparison. Results obtained in this study indicate that indeed, in acidic media, one should consider the protonated species involved because they seem to represent better the actual experimental situation.