HIGH FREQUENCY (95 GHZ) EPR SPECTROSCOPY TO CHARACTERIZE SPIN ADDUCTS

用于表征自旋加合物的高频 (95 GHZ) EPR 光谱

• 批准号: 6120683
• 负责人: TATYANA I SMIRNOVA
• 金额: $ 0.27万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-15 至 1999-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6120683
• 关键词: biological products; biomaterials; biomedical resource; computers

Spin trapping experiments are usually carried out with continuous-wave (cw) X-band (9.5 GHz) EPR spectroscopy because of the good concentration sensitivity and ready availability of this method. Characterization of the spin adducts is usually based on analysis of isotropic hyperfine coupling and comparison of these coupling factors with those for the reference spin adducts. These experiments encounter two major challenges: (i) spin adducts from many carbon-centered free radicals have close g-values (resulting in strongly overlapping spectra), and (ii) measurable hyperfine couplings correspond to interactions of the electron spin with just the nearest nuclei. Therefore, very little or no information is obtained on the overall structure of the spin adduct molecule. In this presentation we demonstrate how high frequency EPR at 95 GHz (W-band) with enhanced g-value resolution and sensitivity to sotational motion can be applied to solve some of these problems. Ten-fold better g-value resol ution allows us, e.g., to clearly separate methyl and trichloromethyl phenyl-tert-butylnitrone (PBN) from a mixture at W-band while the presence of two species is practically unnoticeable in the corresponding X-band EPR spectra. Rotational dynamics parameters can be measured much more accurately at W-band, providing information on rotational radii which characterize the adduct molecule as a whole.

自旋捕获实验通常用 连续波（cw）X波段（9.5 GHz）EPR光谱，因为 该方法具有浓度灵敏度高、操作简便等优点。 自旋加合物的表征通常基于对以下物质的分析： 各向同性超精细耦合及其耦合因子比较 与参比自旋加合物的结果一致。 这些实验 遇到两个主要挑战：（i）来自许多 以碳为中心的自由基具有接近的g值（导致 强烈重叠光谱），和（ii）可测量的超精细耦合 对应于电子自旋与最近的 原子核。 因此，很少或没有获得关于 自旋加合物分子的总体结构。 本演示文稿中 我们演示了如何在95 GHz（W波段）的高频EPR与增强 可以应用g值分辨率和对振动运动的灵敏度 来解决这些问题。 g值分辨率提高10倍 允许我们，例如，将甲基和三氯甲基 苯基-叔丁基硝酮（PBN）的混合物在W波段，而 两个物种的存在实际上是不明显的， 相应的X波段EPR谱。 旋转动力学参数可以 在W波段更准确地测量，提供有关 表征加合物分子整体的旋转半径。