Theoretical Analysis of Substituent Effects on Iron Corrosion Inhibition Capability of Phenylalanine and Its Derivatives

The corrosion inhibition activity of phenylalanine derivatives has been systematically examined by calculating quantum chemical parameters at the B3LYP/6-311++G(d,p) level. The results consistently demonstrate that derivatives containing the electron-donating groups exhibit superior efficiency in inhibiting iron corrosion compared to phenylalanine. Additionally, an investigation into the corrosion inhibition ability of derivatives containing the $\mathbf{N H}_{2}$ group reveals that $7-\mathrm{NH}_{2}$-phenylalanine emerges as the most effective inhibitor, boasting an efficiency value of 91.99%. These calculated outcomes align with previously studied experimental results, underscoring the remarkable corrosion resistance of derivatives containing electron-donating groups, particularly in acidic environments.