An Investigation into Quantum Chemistry and Experimental Evaluation of Imidazopyridine Derivatives as Corrosion Inhibitors for C-Steel in Acidic Media

The corrosion inhibition performance of two imidazopyridine derivatives, namely 6-nitroso-2-phenylimidazo[1,2-a]pyridine-3 carbaldehyde (C1) and (2-phenylimidazo[1,2-a]pyridin-3-yl)methanol (C2) for carbon steel in 1.0 M hydrochloric acid solution, was evaluated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and quantum chemical calculations. The surface morphology was examined using Scanning Electron Microscopy (SEM). Imidazopyridine derivatives adsorbed onto the carbon steel surface via mixed types of adsorption with predominantly chemisorption obeying Langmuir adsorption isotherm. DFT computational chemistry at B3LYP/6-31G(d,p) basis set level was applied in order to correlate some electronic properties of tested molecules to the inhibition efficiencies obtained from experimental data. The computed Fukui functions have been useful to predict the reactive sites of nucleophilic and electrophilic attacks.