Experimental and theoretical evaluation of the anticorrosive proprieties of new 1,2,3-triazolyl-acridine derivatives

Three novel 1,2,3-triazolyl-acridine derivatives (abbreviated as TTA, ATM, and ATA) were synthesized via a fast ultrasound-assisted copper-catalyzed azide-alkyne cycloaddition (CuAAC) in good yields. They were studied as corrosion inhibitors for 1020 mild steel in acidic media (1 mol/L HCl) using gravimetric and electrochemical measurements. Weight Loss Study showed that those molecules have anticorrosive efficiency varying from 85 to 94 % at 1 mmol/L (298 K). They also increased their corrosion mitigation at higher temperatures, reaching up to 90-96 % at 338 K. Isotherm fitting revealed that all developed corrosion inhibitors follow the Langmuir theory and data crossing confirmed the monolayer formation. Atomic Force Microscopy suggested the presence of a protective film on the metal surface and Electrochemical Impedance Spectroscopy, Linear Polarization Resistance, and Electrochemical Frequency Modulation showed a better charge transfer and polarization resistance alongside a lower corrosion current density in the presence of TTA, ATM, and ATA in the corrosive media. Also, polarization curves characterized all three organic molecules as mixed-type corrosion inhibitors for mild steel. First-principles density functional theory (DFT) simulations revealed that all molecules form covalent bonds with iron atoms upon adsorption on Fe(1 1 0) surface. The ATA molecule exhibited a bond-breaking upon adsorption and had a higher interaction energy with the iron surface. The chemical interactions between inhibitors' molecules and iron atoms were confirmed by projected density of states analysis, showing a strong hybridization between molecules' orbitals and 3d iron orbitals.