Effect of the phosphoryl substituent in the linear nitrone on the spin trapping of superoxide radical and the stability of the superoxide adduct: Combined experimental and theoretical studies
Effect of the phosphoryl substituent in the linear nitrone on the spin trapping of superoxide radical and the stability of the superoxide adduct: Combined experimental and theoretical studies
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DOI：
10.1021/jo061204m
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发表时间：
2006-09-29
影响因子：
3.6
通讯作者：
Tian, Qiu
中科院分区：
文献类型：
--
作者：
Liu, Yang-Ping;Wang, Lan-Fen;Tian, Qiu
合成了一种新的磷酸化线性硝酮N-（4-羟基亚苄基）-1-二乙氧基磷酰基-1-甲基乙胺N-氧化物（4-HOPPN），并测定了其X射线结构。评价了4-HOPPN对各种自由基的自旋捕获能力。超氧自由基自旋加合物的衰变动力学研究（4-HOPPN-OOH）显示半衰期为8.8 min。基于X射线结构坐标，在B3 LYP/6-31+ G（d，在p）//B3 LYP/6- 31 G（d）水平上研究了超氧自由基与4-HOPPN和PBN及其相应的超氧化物加合物的三种可能的衰变途径。通过对超氧自由基自旋捕获反应的比较计算，预测了两种自旋捕获剂具有相同的反应类型，并且在捕获超氧自由基时具有相当的能力。对4-HOPPN-OOH和PBN-OOH的优化几何构型的分析表明，磷酰基的引入可以通过分子内氢键、分子内非键吸引相互作用以及大体积的空间位阻保护作用有效地稳定自旋加合物.对4-HOPPN-OOH和PBN-OOH的分解热力学的研究进一步支持了磷酰基对线性磷酸化自旋加合物的稳定作用。
A new phosphorylated linear nitrone N-(4-hydroxybenzyliene)-1-diethoxyphosphoryl-1-methylethylamine N-oxide (4-HOPPN) was synthesized, and its X-ray structure was determined. The spin trapping ability of various kinds of free radicals by 4-HOPPN was evaluated. Kinetic study of decay of the superoxide spin adduct (4-HOPPN-OOH) shows the half-life time of 8.8 min. On the basis of the X-ray structural coordinates, theoretical analyses using density functional theory (DFT) calculations at the B3LYP/6-31+ G(d,p)//B3LYP/6-31G(d) level were performed on spin-trapping reactions of superoxide radical with 4-HOPPN and PBN and three possible decay routes for their corresponding superoxide adducts. The comparative calculations on the spin-trapping reactions with superoxide radical predicted that both spin traps share an identical reaction type and have comparable potency when spin trapping superoxide radical. Analysis of the optimized geometries of 4-HOPPN-OOH and PBN-OOH reveals that an introduction of the phosphoryl group can efficiently stabilize the spin adduct through the intramolecular H-bonds, the intramolecular nonbonding attractive interactions, as well as the bulky steric protection. Examination of the decomposition thermodynamics of 4-HOPPN-OOH and PBN-OOH further supports the stabilizing role of the phosphoryl group to a linear phosphorylated spin adduct.