Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic surface. In this work, three heterocyclic compounds such as 1-azanaphthalene-8-ol (8-AN), 2-methylquinoline-8-ol (8-MQ), and 8-quinolinol-5-sulfonic acid (8-QSA) were used as green compounds, and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface analysis. Findings found that the electrochemical performance was improved in the order of 8-AN > 8-MQ > 8-QSA, demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium surface. From the electrochemical performance, the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments, with potential inhibition efficiency of 87.4%, 99.0%, and 99.9% for 8-QSA, 8-MQ, and 8-AN, respectively. Quantum chemical parameters and electron density distribution for free organic species in the absence and presence of Mg²⁺ cation were evaluated using density functional theory (DFT). Upon the formation of coordination complexes between organic compound and Mg²⁺, energy gap underwent change about ∆E = 5.7 eV in the 8-AN/Mg²⁺ system. Furthermore, the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms, which further confirmed by the electron density difference and projected density of states analyses. Based on theoretical calculations, three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C, O and N atoms. In the parallel configuration, the C-Mg, N-Mg and O-Mg bond distances are between 2.11 and 2.25 Å, whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40 Å (covalent bonds via O and N atoms). The results indicated that parallel configurations are energetically more stable, in which the adsorption energies are -4.48 eV (8-AN), -4.28 eV (8-MQ) and -3.82 eV (8-QSA) compared to that of perpendicular adsorption (-3.65, -3.40, and -2.63 eV). As a result, experimental and theoretical studies were in well agreement and confirm that the nitrogen and oxygen atoms will be the main adsorption sites.

杂环化合物是一种很有前途的生物化合物，对金属表面的腐蚀保护具有自然友好性。在这项工作中，三种杂环化合物如 1-azanaphthalene-8-ol (8-AN)、2-methylquinoline-8-ol (8-MQ) 和 8-quinolinol-5-sulfonic acid (8-QSA)用作绿色化合物，并在阻抗解释和表面分析的基础上讨论了它们对AZ31 Mg在盐水中的防腐性能。结果发现，电化学性能的提高顺序为8-AN > 8-MQ > 8-QSA，证明了N-杂环在镁表面形成配位络合物的电子供体效应。从电化学性能来看，以最佳浓度构建的保护层增强了对侵蚀性环境的屏障，8-QSA、8-MQ 和 8-AN 的潜在抑制效率分别为 87.4%、99.0% 和 99.9%。存在和不存在 Mg 时游离有机物的量子化学参数和电子密度分布使用密度泛函理论 (DFT) 评估^{2+阳离子。有机化合物与Mg 2+}形成配位化合物后，  8-AN/Mg ²⁺中的能隙发生变化，ΔE = 5.7 eV系统。此外，杂环化合物在镁表面的吸附揭示了与镁原子形成强共价键，电子密度差和投影态密度分析进一步证实了这一点。根据理论计算，三种抑制剂可以通过C、O和N原子以平行和垂直方向吸附在金属表面。在平行配置中，C-Mg、N-Mg 和 O-Mg 键距在 2.11 和 2.25 之间，而垂直吸附情况下的距离在 2.20 和 2.40 之间（通过 O 和 N 原子的共价键） . 结果表明平行配置在能量上更稳定，与垂直吸附相比，平行配置的吸附能为-4.48 eV（8-AN），-4.28 eV（8-MQ）和-3.82 eV（8-QSA）（ -3.65、-3.40 和 -2。63 电子伏特）。结果，实验和理论研究非常一致，并证实氮和氧原子将是主要的吸附位点。