Experimental and Computational Studies of Two Cu (II) and Zn (II) Coordination Polymers Based on Acyclic Cryptate-Bis(1H-1,2,4-Triazole) as Promising Corrosion Inhibitors in Molar HCl Medium.

The inhibition potential of two new 1D coordination polymers (CP), CuL₂(NO₃)₂ (C₁) and ZnL₂(BF₄)₂ (C₂), and their cryptate-bis(1H-1,2,4-triazole)-based ligand (L₁) against the corrosion of mild steel (MS) in molar hydrochloric acid medium was evaluated by employing the weight loss (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques. In addition, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) was used to assess the surface of the steel before and after corrosion. UV–visible spectroscopy was used to examine the gravimetric solution, and to fully understand the inhibitory effect, we employed quantum chemical descriptors and Monte Carlo simulation. Based on the outcomes of the electrochemical and computational research, combined with characterization of the metal surface morphology, both metal complexes were found to be highly effective compared to the parent ligand. The findings of the EIS measurements showed that at 308 K, complexes C₁ and C₂ retained their inhibitory efficiency at levels over 92.3%. Furthermore, these compounds are of the mixed type, and their adsorption on the MS face was found to follow the Langmuir adsorption isotherm with the free energies of adsorption of − 42.3 and − 46.2 kJ mol⁻¹, respectively. The experimental findings were reinforced by quantum computations and computer simulation. [ABSTRACT FROM AUTHOR]