Abstract

Majid Khodaei-Tehrani¹* and Ali Niazi

DOI : http://dx.doi.org/10.13005/ojc/310150

The density functional theory (DFT) at the B3LYP/6-31G (d,p) basis set level method were performed on three hector bases used as corrosion inhibitors; namely, 3-anilino-5-imino-4-phenyl-1, 2,4-thiadiazoline (AIPT), 3-anilino-5-imino-4-tolyl-1, 2,4-thiadiazoline (AITT), and 4-(4-chlorophenyl)-5-imino-N-phenyl-4,5-dihydro-1,2,4-thiadiazol-3-amine (AICT). They were used as corrosion inhibitors for mild steel in acidic medium in order to determine the relationship between molecular structure and their corresponding inhibition efficiency (%IE). The results of the quantum chemical calculations and experimental %IE were subjected to correlation analysis. This indicates that their inhibition effects are closely related to the highest occupied molecular orbital energy (E_HOMO), the lowest unoccupied molecular orbital energy (E_LUMO), the energy gap (ΔE), the hardness (η), the softness (σ), the electronegativity (χ), and the fraction of electrons transferred from the inhibitor molecule to the metal surface (ΔN). In addition, the local reactivity has been analyzed through the Fukui function. Two QSAR equations were developed and used to predict the corrosion inhibition efficiency for hector bases.

hector bases; Inhibition of corrosion; Quantum chemical parameters; Fukui function

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