Combined DFT and Monte Carlo simulation studies of potential corrosion inhibition properties of heterocyclic derivatives with an extended π-System

Sustainable corrosion inhibitors play a crucial role as corrosion results in substantial economic and environmental harm. The objective of this study was to investigate in silico the corrosion inhibition capabilities of a series of the closely related heterocyclic compounds containing oxygen, sulfur and nitrogen atoms, namely namely dibenzofuran (1), 1 ), dibenzothiophene (2), 2 ), phenoxazine (3), 3 ), phenothiazine (4), 4 ), benzoxazole (5), 5 ), benzothiazole (6), 6 ), xanthene (7) 7 ) and thioxanthene (8), 8 ), using the DFT/B3LYP/6-311++G(d,p) ++G(d,p) basis set. In addition, Monte Carlo simulations were applied to reveal adsorption of the studied compounds on the Fe(1 1 0) and Cu (11 1) surfaces. It was established that all the studied compounds exhibit good molecule-to-metal electron charge transfer for both metals, of which compounds 3 and 4 , followed by 7 and 8 , exhibit the best results. The Monte Carlo simulations predicted that compounds 4 and 8 exhibit the lowest adsorption energy with the Fe(1 1 0) surface, while the same energy absolute value is about two times lower for the Cu(1 11) surface. This allowed to conclude that compounds 4 and 8 are the most promising candidates among the series of the studied compounds for inhibiting corrosion on both iron and copper.