Indirect detection of mercury-199 nuclear magnetic resonance spectra of methylmercury complexes.
Indirect detection of mercury-199 nuclear magnetic resonance spectra of methylmercury complexes.
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DOI：
10.1021/ac00023a003
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发表时间：
1991-12
影响因子：
7.4
通讯作者：
J. Robert;D. Rabenstein
中科院分区：
文献类型：
--
作者：
J. Robert;D. Rabenstein
本文介绍了用HMQC间接质子探测法测量甲基汞的~（199）Hg NMR谱，并将其应用于CH_3HgII-硫醇配体络合物的溶液化学研究。通过间接检测方法测量4 mM CH 3 HgII-谷胱甘肽复合物溶液的199 Hg NMR光谱，获得灵敏度增强因子为16，而理论增强因子为74。低于理论的增强归因于HMQC脉冲序列期间弛豫导致的信号损失。纵向弛豫的199汞在CH 3 HgII硫醇盐复合物是快速在本研究中使用的场强（11.7 T）由于有效的弛豫的化学位移各向异性机制。这反过来又导致199 Hg自旋耦合甲基质子的横向弛豫速率很快，这是由于另一种机制的有效弛豫，即第二类标量弛豫。根据CH 3 HgII在其复合形式之间的交换速率，199 Hg的线宽也可以包括来自交换加宽的大贡献。在这种情况下，它表明，非常广泛的199 Hg共振，这将是很难检测到的方向观察，可以观察到的间接检测方法。例如，199 Hg共振与交换加宽的线宽高达8000赫兹观察到的间接检测方法为CH 3 HgII的混合物中的CH 3 HgOD和CH 3 HgII-巯基乙醇或CH 3 HgII-谷胱甘肽复合物。199 Hg在CH_3HgII-硫醇配体配合物中的化学位移被发现对硫醇配体的性质非常敏感。（250字处删节）
Measurement of 199Hg NMR spectra of methylmercury species by the heteronuclear multiple quantum coherence (HMQC) indirect proton detection method and its application to the study of the solution chemistry of CH3HgII-thiol ligand complexes are described. A sensitivity enhancement factor of 16 is obtained for measurement of the 199Hg NMR spectrum of a 4 mM solution of the CH3HgII-glutathione complex by the indirect detection method, as compared to a theoretical enhancement of 74. The less-than-theoretical enhancement is attributed to loss of signal by relaxation during the HMQC pulse sequence. Longitudinal relaxation of the 199Hg in CH3HgII-thiolate complexes is fast at the field strength used in this research (11.7 T) due to efficient relaxation by the chemical shift anisotropy mechanism. This in turn causes the transverse relaxation rate for the 199Hg spin-coupled methyl protons to be fast due to efficient relaxation by another mechanism, scalar relaxation of the second kind. Depending on the rate of exchange of CH3HgII among its complexed forms, the 199Hg line width can also include a large contribution from exchange broadening. In such cases, it is shown that extremely broad 199Hg resonances, which would be difficult to detect by direction observation, can be observed by the indirect detection method. For example, 199Hg resonances with exchange-broadened line widths up to 8000 Hz are observed by the indirect detection method for CH3HgII in mixtures of CH3HgOD and the CH3HgII-mercaptoethanol or CH3HgII-glutathione complex. The chemical shift of 199Hg in CH3HgII-thiolate ligand complexes is found to be extremely sensitive to the nature of the thiolate ligand.(ABSTRACT TRUNCATED AT 250 WORDS)