Theoretical studies on corrosion inhibition of N-aroyl-N’-aryl thiourea derivatives using conceptual DFT approach

In this paper, quantum chemical parameters at density functional theory (DFT) B3LYP/6-31G** (d,p) level of theory were calculated for three organic corrosion inhibitors [N-benzoyl-N-(p-aminophenyl) thiourea, N-benzoyl-N-(thiazole) thiourea and N-acetyl-N-(dibenzyl) thiourea. The calculated molecular descriptors such as the HOMO, LUMO, dipole moment, chemical potential (μ), chemical hardness (ղ), global nucleophilicity (ω) and average electronic charges on nitrogen atoms were explained in line with the experimental observed inhibitory efficiency for the compounds. The calculated results revealed that electron density on the rings (Qring (e)) and thiocarbonyl sulphur atom (S* in C=S) are strongly correlated to the observed %IE. Therefore, electronic interactions such as π-cationic and n-cationic interactions between the molecules and metal surface played prominent roles in adsorption process than electron donor-acceptor model as early reported by Uday et al., 2013 [19].