Spin trapping by 5-carbamoyl-5-methyl-1-pyrroline N-oxide (AMPO): theoretical and experimental studies.
Spin trapping by 5-carbamoyl-5-methyl-1-pyrroline N-oxide (AMPO): theoretical and experimental studies.
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DOI：
10.1021/jo049244i
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
F. Villamena;A. Rockenbauer;J. Gallucci;M. Velayutham;C. Hadad;J. Zweier
中科院分区：
文献类型：
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作者：
F. Villamena;A. Rockenbauer;J. Gallucci;M. Velayutham;C. Hadad;J. Zweier
合成并表征了硝酮5-氨甲酰基-5-甲基-1-吡咯啉N-氧化物（AMPO）。电子顺磁共振（EPR）谱首次证实了AMPO对各种自由基的自旋捕获。这些自由基中的每一个产生的自旋加合物给出了独特的光谱轮廓。超氧化物加合物的超精细分裂常数如下：异构体I（80%），a（硝酰基）（-）（N）= 13.0 G和a（β）（-）（H）= 10.8 G;异构体II（20%），a（硝酰基）（-）（N）= 13.1 G，a（β）（-）（H）= 12.5 G和a（γ）（-）（H）= 1.75 G。AMPO-O（2）H的半衰期约为8 min，与EMPO观察到的半衰期相似，但明显短于DEPMPO-O（2）H的半衰期，t（1/2）约为16 min。然而，AMPO-O（2）H在高S/N比下的光谱图与（*）OH加合物的光谱图不同。采用密度泛函理论（DFT）在B3 LYP/6-31+G//B3 LYP/6- 31 G水平上对AMPO及其超氧加合物进行了理论分析.计算预测的存在下，分子内的H-键合的AMPO和超氧化物加合物。通过对AMPO和类似的酰胺硝酮2-氨基-5-氨甲酰基-5-甲基-1-吡咯啉N-氧化物（NH（2）-AMPO）的X-射线结构分析，进一步证实了氢键的相互作用。各种硝酮捕获超氧自由基的热力学量已被发现预测某些异构体的形成。在正辛醇/缓冲液体系中，AMPO的分配系数与DMPO和DEPMPO的分配系数相似。这项研究表明，AMPO硝酮用作自旋陷阱，研究自由基在水溶液中的生产的适用性。
The nitrone 5-carbamoyl-5-methyl-1-pyrroline N-oxide (AMPO) was synthesized and characterized. Spin trapping of various radicals by AMPO was demonstrated for the first time by electron paramagnetic resonance (EPR) spectroscopy. The resulting spin adducts for each of these radicals gave unique spectral profiles. The hyperfine splitting constants for the superoxide adduct are as follows: isomer I (80%), a(nitronyl)(-)(N) = 13.0 G and a(beta)(-)(H) = 10.8 G; isomer II (20%), a(nitronyl)(-)(N) = 13.1 G, a(beta)(-)(H) = 12.5 G, and a(gamma)(-)(H) = 1.75 G. The half-life of the AMPO-O(2)H was about 8 min, similar to that observed for EMPO but significantly shorter than that of the DEPMPO-O(2)H with t(1/2) approximately 16 min. However, the spectral profile of AMPO-O(2)H at high S/N ratio is distinguishable from the spectrum of the (*)OH adduct. Theoretical analyses using density functional theory calculations at the B3LYP/6-31+G//B3LYP/6-31G level were performed on AMPO and its corresponding superoxide adduct. Calculations predicted the presence of intramolecular H-bonding in both AMPO and its superoxide adduct. The H-bonding interaction was further confirmed by an X-ray structure of AMPO, and of the novel and analogous amido nitrone 2-amino-5-carbamoyl-5-methyl-1-pyrroline N-oxide (NH(2)-AMPO). The thermodynamic quantities for superoxide radical trapping by various nitrones have been found to predict favorable formation of certain isomers. The measured partition coefficient in an n-octanol/buffer system of AMPO was similar to those of DMPO and DEPMPO. This study demonstrates the suitability of the AMPO nitrone for use as a spin trap to study radical production in aqueous systems.