Effect of substituents in 5-R-3-amino-1,2,4-triazoles on the chemisorption on copper surface in neutral media

Abstract

Using a complex of physical and electrochemical methods, the effect of R-substituent on the adsorption of 5-R-3-amino-1,2,4-triazoles on copper surface in neutral buffer solution was studied. Minimum concentrations C _min, which suppresses the first anodic peak of copper dissolution were found, and two different linear correlations of log C _min values on induction constant σ_I were plotted: for compounds with electron-donor and electron-withdrawing ones. Using ellipsometry, free adsorption energies −ΔG ⁰ _а,max were determined. It was shown that adsorption of triazoles with electron acceptor R, which have the highest σ_I, occurs at very low concentrations and −ΔG ⁰ _а,max = 96.6 kJ mol⁻¹ that is higher than for inhibitors of the same reaction series, but with electron-donor R (70 ÷ 85 kJ mol⁻¹). In this case, monolayers are formed, whose thicknesses are close to molecule size. The formation of chemisorption bonds is confirmed using XPS by studying the composition of adsorption layers formed by 5-CF₃-3-amino-1,2,4-triazole on the copper surface.