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5-氨基-2-巯基-1,3,4-噻二唑(AMT)能和青铜器表面铜离子作用生成一种配位型聚合物的保护膜[AMT-Cu(Ⅰ)]n,并将腐蚀层中的氯离子置换出来,避免了青铜器的进一步腐蚀.为了深入了解AMT的缓蚀作用机理,本文采用密度泛函理论(DFT)和自然键轨道理论(NBO),在B3LYP/6-31+G(d,p)水平上确定AMT中反应活性位点、活性原子所带电荷和杂化形式,并利用Multiwfn波函数分析了反应前后前线轨道能的变化.结果表明,-SH基中的S7原子能与Cu(Ⅱ)形成有效的共价键,而N6原子可与Cu(Ⅱ)形成配位键,促进聚合物膜[AMT-Cu(Ⅰ)]n的形成,并且从概念DFT的活性指数(主要为μ,η,ω,ΔEn,ΔEe)比较中发现,AMT-Cu(Ⅰ)-H较AMT的亲电性指数增加,有利于形成高聚物膜,而且反应前后AMT构型中的C、N、S却始终在同一平面,但C-S和C-N键键长和键角均有不同程度的变化.
5-Amino-2-mercapto-1,3,4-thiadiazole (AMT) can act as a protective film [AMT-Cu (I)] n to the copper ion on the surface of bronze, In order to further understand the mechanism of corrosion inhibition of AMT, chloride ion in the corrosion layer is replaced to avoid further corrosion of the bronze.In order to further understand the corrosion inhibition mechanism of AMT, this paper adopts density functional theory (DFT) and natural bond orbital theory (NBO) + G (d, p), the active sites in the AMT and the charges and hybrids of the active atoms were determined. The changes of the orbital energies before and after the reaction were analyzed by the Multiwfn wave function. The results show that the S7 atom can form effective covalent bond with Cu (Ⅱ), while N6 atom can form coordination bond with Cu (Ⅱ) to promote the formation of polymer film [AMT-Cu (Ⅰ)] n, It was found that the electrophilicity index of AMT-Cu (Ⅰ) -H was higher than that of AMT, which was in favor of the formation of high polymer film. Moreover, in the AMT configuration before and after the reaction C, N, S are always in the same plane, but the CS and CN key length and key angle have different degrees of change.