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首页> 外文期刊>Journal of molecular modeling >DFTstudy of the effect of solvent on the H-atom transfer involved in the scavenging of the free radicals ~●HO_2 and ~●O_2~- by caffeic acid phenethyl ester and some of its derivatives
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DFTstudy of the effect of solvent on the H-atom transfer involved in the scavenging of the free radicals ~●HO_2 and ~●O_2~- by caffeic acid phenethyl ester and some of its derivatives

机译：DFT研究溶剂对咖啡酸苯乙酯及其衍生物清除自由基〜●HO_2和〜●O_2〜-所涉及的H原子转移的影响

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H-atom transfer from caffeic acid phenethyl ester (CAPE), MBC (3-methyl-2-butenyl caffeate), BC (benzoic caffeate), P3HC (phenethyl-3-hydroxycinnamate), and P4HC (phenethyl-4-hydroxycinnamate) to the selected free radicals ~●HO_2 and ~●O_2~- was studied. Such a transfer can proceed in three different ways: concerted proton-coupled electron transfer (CPCET), electron transfer followed by proton transfer (ET-PT), and proton transfer followed by electron transfer (PT-ET). The latter pathway is sometimes competitive with SPLET (sequential proton loss electron transfer) in polar media. Analyzing the thermodynamic descriptors of the reactions of CAPE and its derivatives with co-reactive species-in particular, the free energies of reactions, the activation barrier to the CPCET mechanism, and their rate constants-appears to be the most realistic method of investigating the H-atom transfers of interest. These analyses were performed via DFT calculations, which agree well with the data acquired from experimental studies (IC50) and from CBS calculations. The CPCM solvation model was used throughout the work, while the SMD model-employed as a reference-was used only for CAPE. The main conclusion drawn from the analysis was that SPLET is the mechanism that governs the reaction of phenolic acids with ~●HO_2, while PT-ET governs the reaction of phenols with ~●O_2~-. In kinetic investigations of the CPCET process, the rate constant decreases as the solvent polarity increases, so the reaction velocity slows down.
机译：H原子从咖啡酸苯乙酯（CAPE），MBC（3-甲基-2-丁烯基咖啡酸酯），BC（苯甲酸咖啡酸酯），P3HC（苯乙基-3-羟基肉桂酸酯）和P4HC（苯乙基-4-羟基肉桂酸酯）转移到研究了选定的自由基〜●HO_2和〜●O_2〜-。这样的转移可以以三种不同的方式进行：质子耦合电子转移协同（CPCET），电子转移后的质子转移（ET-PT）和质子转移后的电子转移（PT-ET）。后一种途径有时与极性介质中的SPLET（顺序质子损失电子转移）竞争。分析CAPE及其衍生物与共反应物种的反应的热力学描述符-特别是反应的自由能，CPCET机制的活化障碍及其速率常数-似乎是研究该反应最现实的方法。感兴趣的H原子转移。这些分析是通过DFT计算进行的，与从实验研究（IC50）和CBS计算获得的数据非常吻合。在整个工作中都使用了CPCM溶剂化模型，而用作参考的SMD模型仅用于CAPE。从分析中得出的主要结论是，SPLET是控制酚酸与〜●HO_2反应的机理，而PT-ET控制酚与〜●O_2〜-的反应。在CPCET过程的动力学研究中，速率常数随着溶剂极性的增加而降低，因此反应速度变慢。

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