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首页> 外文期刊>Physical chemistry chemical physics: PCCP >EPR, ENDOR, TRIPLE resonance spectroscopy and MO studies on radical anion, neutral radical and radical cation of vitamin K_3 in a selection of solvents
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EPR, ENDOR, TRIPLE resonance spectroscopy and MO studies on radical anion, neutral radical and radical cation of vitamin K_3 in a selection of solvents

机译：EPR，ENDOR，TRIPLE共振光谱和MO研究维生素K_3在某些溶剂中的自由基阴离子，中性自由基和自由基阳离子

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摘要

All three radical species (radical anion, neutral radical and radical cation) from 2-methyl-1,4-naphthoquinone (vitamin K_3) were prepared in liquid solutions and measured by EPR and ENDOR/TRIPLE resonance spectroscopy. The methyl group protons showed the largest variation of isotropic hyperfine coupling, from 8.3 MHz (anion) to 19.1 MHz (neutral) to 9.3 MHz (cation). Isotropic hyperfine couplings of a proton in the quinoid ring and the methyl group protons in different solutions were shown to be dependent on the relative permittivity of the solvent. A prominent alternating linewidth effect was detected in the EPR spectra of the radical anion of 2-methyl-1,4-naphthoquinone at different concentrations and at different temperatures in 1,2-dimethoxyethane. This was explained as being due to the counter-cation fluctuation between the two quinodic oxygens. A solid dipotassium radical salt of vitamin K_3 was prepared and its EPR spectra measured. Isotropic hyperfine coupling constants were also calculated for all three radical species using the UB3LYP density functional method.
机译：来自2-甲基-1,4-萘醌（维生素K_3）的所有三种自由基物质（自由基阴离子，中性自由基和自由基阳离子）均在液体溶液中制备，并通过EPR和ENDOR / TRIPLE共振光谱法进行测量。甲基质子表现出最大的各向同性超精细偶联变化，从8.3 MHz（阴离子）到19.1 MHz（中性）到9.3 MHz（阳离子）。醌环中的质子与不同溶液中的甲基质子的各向同性超精细偶合显示出取决于溶剂的相对介电常数。在1,2-二甲氧基乙烷中，在不同浓度和温度下，2-甲基-1,4-萘醌的自由基阴离子的EPR光谱中检测到显着的交替线宽效应。这被解释为是由于两个喹啉氧之间的抗衡阳离子波动引起的。制备了维生素K_3的固体二钾自由基盐，并测量了其EPR光谱。还使用UB3LYP密度泛函方法计算了所有三种自由基的各向同性超细偶合常数。

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