This review accounts for the most recent and significant research results from the literature on the design and synthesis of 1,2,3-triazole compounds and their usefulness as molecular well-defined corrosion inhibitors for steels, copper, iron, aluminum, and their alloys in several aggressive media. Of particular interest are the 1,4-disubstituted 1,2,3-triazole derivatives prepared in a regioselective manner under copper-catalyzed azide-alkyne cycloaddition (CuAAC) click reactions. They are easily and straightforwardly prepared compounds, non-toxic, environmentally friendly, and stable products to the hydrolysis under acidic conditions. Moreover, they have shown a good efficiency as corrosion inhibitors for metals and their alloys in different acidic media. The inhibition efficiencies (IEs) are evaluated from electrochemical impedance spectroscopy (EIS) parameters with different concentrations and environmental conditions. Mechanistic aspects of the 1,2,3-triazoles mediated corrosion inhibition in metals and metal alloy materials are also overviewed.

Two triazole derivatives with phosphonic acid as pendent group, namely [3-(4-phenyl-[1–3]triazol-1-yl)-propyl]-phosphonicaciddiethylester (PTP) and [3-[4-(4-dimethylamino-phenyl)-[1–3]triazol-1-yl]-propyl]-phosphonic acid diethylester (DMPTP) were synthesized and fully characterized using NMR spectroscopy, Mass spectrometry, Infra-Red (FT-IR) spectroscopy and elemental analysis. The synthesized multifunctional heterocycles were investigated to inhibit the corrosion of mild steel in acidic solution HCl (1 M) by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and weight loss measurements. The results of the different corrosion measurement techniques are in good agreement. The potentiodynamic polarization analysis shows that the PTP and DMPTP derivatives are mixed-type inhibitors. In addition, EIS measurements were used to simulate the corrosion inhibition process by using a suitable equivalent circuit. The thermodynamic and kinetic parameters obtained demonstrated that both inhibitors adsorb to the surface of mild steel according to the Langmuir model’s isotherm. A layer adsorbed onto the surface of the mild steel has been confirmed by FT-IR, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. Moreover, Density Functional Theory (DFT) analysis and Molecular Dynamics simulations (MD) have been carried out, the computational results agreeing with the experimental ones.

The reaction of copper(II) acetate with the 2-aminobenzothiazole (abt) heterocycle affords the new copper(II) complex of formula [Cu(abt)₂(OOCCH₃)₂] (1) in a straightforward manner. Compound 1 served as a precatalyst for azide/alkyne cycloaddition reactions (CuAAC) in water, leading to 1,4-disubstituted-1,2,3-triazole derivatives in a regioselective manner and with excellent yields at room temperature. The main advantages of the coordination of such a heterocyclic ligand in 1 are its strong σ-donating ability (N-Cu), nontoxicity and biological properties. In addition, the click chemistry reaction conditions using 1 allow the formation of a great variety of 1,2,3-triazole-based heterocyclic compounds that make this protocol potentially relevant from biological and sustainable viewpoints. A molecular electron density theory (MEDT) study was performed by using density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) (LANL2DZ for Cu) level to understand the observed regioselectivity in the CuAAC reaction. The intramolecular nature of this reaction accounts for the regioselective formation of the 1,4-regioisomeric triazole derivatives. The ionic nature of the starting copper-acetylide precludes any type of covalent interaction throughout the reaction, as supported by the electron localization function (ELF) topological analysis, reaffirming the zwitterionic-type (zw-type) mechanism of the copper(I)/aminobenzothiazole-catalysed azide-alkyne cycloaddition reactions.

The effect of an heterocycle triazole, namely (1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methanol (MTM) on the corrosion of mild steel in hydrochloric acid solution has been investigated...

A novel bis-isoxazole was synthesized from (R)-Carvone and p-methylbenzaldoxime, via two successive [3+2] cycloaddition reactions (32CA). The newly obtained bis-isoxazole has been fully characterized by HRMS and NMR spectroscopy. The HMBC experiment was performed to determine the stereo and the regioselectivity of the reaction. The electrochemical behavior of the studied compound, in oxidation and reduction processes, was examined using the cyclic voltammetry technique. In addition, the regioselectivity of the [3+2] cycloaddition reaction and the molecular structure of the title compound was performed by density functional theory (DFT). The HOMO and LUMO orbitals were investigated to determine the electronic properties of the synthesized compound. Besides, the global reactivity indexes were used to explain the regioselectivity for the formation of the bis-isoxazole, the theoretical results are in good agreement with experimental findings.