600 MHz NMR spectrometer

本文提出了一种新型600 MHz液体核磁共振谱仪，其探头为氮气冷却的低温探头，具有“正常”线圈排列(内为X，外为1H/19F)。与室温探头相比，低温技术的使用将信噪比提高了三倍。在给定物质含量的情况下，不仅可以显著缩短测量时间，而且还可以使用2D核磁共振波谱领域中更复杂的测量方法，显著减少测量时间。由于探头的几何形状(内部13C线圈)，该设备将代表显著的增益，特别是在高取代度的天然和活性物质的结构阐明方面，这些物质的特征是高水平的季碳原子。此外，多芳香族体系，如那些主要用于材料科学领域的体系，也具有大量季碳原子的特征，可以更好地表征。另一种方法在新天然产物的生物合成阐明(这里也使用不充分)、活性物质的代谢降解以及在机理阐明领域特别有用，其基础是通过同位素标记(例如2H、15N、18O)转移13C信号。由于低温探针头具有高的13C灵敏度，因此不仅可以通过13C核磁共振谱确定准确位置的同位素标记。相反，同位素含量也可以通过积分来自标记碳原子的13C信号来量化。最后，该装置提供了直接测量动力学同位素效应的可能性，例如通过1H-13C极化转移测量，这是对上述方法的补充。

A modern 600 MHz liquid NMR spectrometer with a nitrogen-cooled cryo probe head with a "normal" coil arrangement (X inside, 1H/19F outside) is proposed. The use of cryo technology improves the signal-to-noise ratio by a factor of three compared to room temperature probes. With a given amount of substance, not only can significant measurement time reductions be achieved, but more complex NMR measurement methods in the field of 2D NMR spectroscopy with significantly reduced measurement times can also be used. Due to the geometry of the probe head (internal 13C coil), this device will represent a significant gain, especially in the structural elucidation of highly substituted natural and active substances that are characterized by a high level of quaternary carbon atoms. Furthermore, polyaromatic systems, such as those used primarily in the field of materials science and which are also characterized by a large number of quaternary carbon atoms, can be characterized much better. Another method that is particularly useful in the field of biosynthesis elucidation of new natural products (here also using INADEQUATE), the metabolic degradation of active substances, as well as in the field of mechanism elucidation is based on the shifting of 13C signals by isotope labeling (e.g. 2H, 15N, 18O). Due to the high 13C sensitivity, which is achieved by the cryo probe head, not only isotope labels can be determined with exact position via 13C NMR spectra. Rather, the isotope content can also be quantified by integrating the 13C signals from labeled carbon atoms. Finally, the device opens up the possibility of direct measurement of a kinetic isotope effect, e.g. by 1H-13C polarization transfer measurements, which is complementary to the method described above.