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The quantitative structure–property relationship (QSPR) models of the inhibition efficiency of seventeen α-amino acids for copper in acidic medium to their calculated reactivity indicators were developed. DFT calculations and Monte Carlo simulations were employed to find out these indicators. Both multi-linear regression (MLR) and artificial neural network (ANN) methods were employed. The most relevant global descriptors were selected using the simulated annealing algorithm. The QSPR studies showed that the inhibiting performance of the investigated compounds was influenced by their electronegativity, LUMO energy, fraction of electron transferred and total negative charge. The results show that the ANN based model exhibits a great predictive performance compared with MLR model according to correlation coefficient and the root-mean-squared error. In addition, this indicates that the corrosion inhibition of copper by these α-amino acids is mainly a complex phenomenon. Moreover, by analysis of local reactivity indicators and using the ANN constructed model, ten new designed derivative compounds with their predicted inhibition efficiency were proposed. Keywords: Corrosion, Modeling, DFT, Monte Carlo, Simulated annealing, QSPR

Three triazoles compounds used as corrosion inhibitors for copper in acidic medium, namely: 1,2,4 triazole (TR), 3-amino 1,2,4 triazole (3 ATR) and 3,5-diamino 1,2,4 triazole (3,5 DATR) have been studied theoretically in aim to investigate the correlation between its molecular reactivity indicators and the corresponding inhibition efficiency. All quantum chemical calculations at the B3LYP/6-31+G(d,p) method were performed with and without solvent effect. In the present paper, not only the neutral inhibitors has been studied, but also the first and the second protonation forms. A good correlation between theoretical and experimental data has been obtained both in gas and aqueous phases, notably for unprotonated inhibitors. Also, the interaction energy between inhibitors and copper has been calculated.

The corrosion inhibition of copper in the presence of 10-3 M of imidazole derivatives; Imidazole (IM), 2-Methyle imidazole (MIM), Benzimidazole (BIM) has been investigated in 1.0 M H2SO4 solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Relationship between molecular structure and their inhibition efficiency was elucidated by quantum chemical calculations using the density functional theory (DFT) at the B3LYP/6-31+G(d,p) level. Inhibition efficiency of these compounds which has been evaluated via experimental methods was accorded with reported theoretical ones, and following the same order as BIM ˃ MIM ˃ IM.