Inhibitory behavior and adsorption of asparagine dipeptide amino acid on the Fe(111) surface.

Context: The inhibitory effect of asparagine (Asn) and its derivatives on iron (Fe) corrosion was studied by performing density functional theory (DFT) calculations. In this paper, the global and local reactivity descriptors of Asn in the protonated and neutral forms were evaluated. Also, the changes in reactivity were investigated when dipeptides were combined with Asn. Due to the increase in the reaction centers within their molecular structure, there was an enhancement in the inhibitory effect of these dipeptides. Moreover, the adsorption energies (E) and the adsorption configurations of Asn and small peptides (SPs) with most stability were determined on the surface of Fe(111). It was found that dipeptides had a chemical adsorption on these substrates. In the protonated forms, there was an enhancement in the absolute values of E between the inhibitors and the Fe(111) surfaces. Peptides were more likely to be adsorbed on the Fe surfaces, showing the great inhibitory effect of these moieties. The results of the current research demonstrate the possibility of utilizing SPs as efficient "green" corrosion inhibitors.

Methods: DFT computations were undertaken by employing the BIOVIA Material Studio with B3LYP-D3 functional and 6-31 + G* basis set. The theoretical evaluation of the inhibitory effect of asparagine (Asn) dipeptides, and the potential analysis of small peptides to protect against the corrosion of Fe, was done.