Effect of hydroxyl group position on adsorption behavior and corrosion inhibition of hydroxybenzaldehyde Schiff bases: Electrochemical and quantum calculations

• Published in: Journal of molecular structure Vol. 1035; pp. 247 - 259
• Main Authors: Danaee, I., Ghasemi, O., Rashed, G.R., Rashvand Avei, M., Maddahy, M.H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 13.03.2013
• Subjects: Ab initio calculation; adsorption; AFM; corrosion; Density functional theory (DFT); electrochemistry; electrodes; hydrochloric acid; hydroxybenzaldehyde; Inhibition; quantitative structure-activity relationships; Schiff base; schiff bases; steel; superoxide anion; Schiff base; AFM; Ab initio calculation; Inhibition; Density functional theory (DFT)
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2012.11.013

► The inhibition ability of Schiff bases against the corrosion of steel was evaluated. ► Schiff bases retard both the cathodic and anodic reactions through chemical adsorption. ► The correlation of inhibition effect and molecular structure was discussed. ► Frontier orbital theory which was applied to the results of quantum chemistry. The corrosion inhibition and adsorption of N,N′-bis(n-hydroxybenzaldehyde)-1,3-propandiimine (n-HBP) Schiff bases has been investigated on steel electrode in 1M HCl by using electrochemical techniques. The experimental results suggest that the highest inhibition efficiency was obtained for 3-HBP. Polarization curves reveal that all studied inhibitors are mixed type. Density functional theory (DFT) at the B3LYP/6-31G(d,p) and B3LYP/3-21G basis set levels and ab initio calculations using HF/6-31G(d,p) and HF/3-21G methods were performed on three Schiff bases. By studying the effects of hydroxyl groups in ortho-, meta-, para- positions, the best one as inhibitor was found to be meta-position of OH in Schiff base (i.e., 3-HBP). The order of inhibition efficiency obtained was corresponded with the order of most of the calculated quantum chemical parameters. Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the Schiff bases studied. The results showed that %IE of the Schiff bases was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the Schiff base studied was found to be close to their experimental corrosion inhibition efficiencies.