Freudenberger J Christoph, Spiteller Peter, Bauer Reinhard, Kessler Horst, Luy Burkhard
Lehrstuhl für Organische Chemie II, Department für Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
J Am Chem Soc. 2004 Nov 17;126(45):14690-1. doi: 10.1021/ja046155e.
The measurement of residual dipolar couplings (RDCs), meanwhile a standard method for obtaining structural information in biomolecular NMR, requires partial alignment of the sample. Special demands on alignment media so far limit the applicability of this approach to small molecules in organic solvents. Major limitations are the free scalability of alignment and the suppression of residual signals of the alignment medium to allow effective measurement of low-concentration samples. Here, we present stretched poly(dimethylsiloxane) (PDMS) cross-linked by beta-rays as an alignment medium with no visible impurities in 1H NMR spectra but a single signal at approximately 0.1 ppm that can easily be removed by slightly modified water suppression methods. Besides the free scalability, its applicability to the measurement of RDCs in small molecules at low concentration is demonstrated on a approximately 12 mM sample of spiroindene. The induced alignment tensor in this case can be predicted reasonably well by a simplified model on the basis of steric interactions only.
同时，残余偶极耦合（RDCs）测量作为在生物分子核磁共振中获取结构信息的标准方法，需要样品进行部分取向。到目前为止，对取向介质的特殊要求限制了这种方法在有机溶剂中小分子的适用性。主要限制在于取向的自由可扩展性以及取向介质残余信号的抑制，以允许对低浓度样品进行有效测量。在此，我们展示了通过β射线交联的拉伸聚二甲基硅氧烷（PDMS）作为一种取向介质，其在1H NMR谱中没有可见杂质，但在约0.1 ppm处有一个单一信号，通过稍微修改的水抑制方法可以很容易地去除。除了自由可扩展性外，在约12 mM的螺茚样品上证明了其在低浓度小分子RDCs测量中的适用性。在这种情况下，仅基于空间相互作用的简化模型就可以相当准确地预测诱导的取向张量。
