Solid-state NMR of unreceptive nuclei

固体核磁共振（SSNMR）是在分子水平上探测固体材料结构和动力学的最强大的技术之一。 虽然大多数NMR应用于有机分子中发现的元素的同位素（例如，1H、13 C、15 N等），还有许多其它的NMR活性核素可以研究。 我们的研究小组专门研究周期表中核素的SSNMR，包括自旋1/2核（例如，89Y、109Ag、195Pt、207Pb等）和四极（自旋> 1/2）核（例如，14N，35Cl，49Ti，65Cu，91Zr）;后者构成约。周期表中73%的核磁共振活性核。 这些核中的许多被分类为不受欢迎的，这意味着由于（i）低NMR频率，（ii）低天然丰度，（iii）由大的各向异性NMR相互作用产生的宽模式，（iv）不方便的弛豫特性或（v）其组合，它们的研究非常具有挑战性。 我的团队利用SSNMR作为主要技术，沿着X射线衍射和量子化学计算来解决各种问题。 特别是，我们致力于开发有效获取许多这些核素的SSNMR光谱的方法，因为它们在化学，生物学和物理学的许多领域都非常重要。 我们应用我们的新方法来研究各种材料，包括（1）用于生产聚合物的多相催化剂，（2）多肽，生物聚合物和其他生物分子，以及（3）固体药物及其多晶型物，它们是由至少两种不同的原子排列产生的纯固体物质的不同相。 最后一个问题特别有趣，因为我们应用基础科学来理解NMR参数与分子结构之间的关系，并利用它来解决与制药行业及其消费者非常相关的问题：即，如何区分药物成分的多晶型物，以便我们可以了解哪些分子相互作用可以改善稳定性，保质期和生物利用度。 此外，每一种多晶型都是可申请专利的，因此我们可以帮助保护知识产权和有价值的专利。

Solid-state nuclear magnetic resonance (SSNMR) is one of the most powerful techniques available for probing structure and dynamics in solid materials at the molecular level. While the majority of NMR is applied to isotopes of elements found in organic molecules (e.g., 1H, 13C, 15N, etc.), there are many other NMR-active nuclides that can be investigated. Our research group specializes in SSNMR of nuclides across the periodic table, including spin-1/2 nuclei (e.g., 89Y, 109Ag, 195Pt, 207Pb, etc.) and quadrupolar (spin > 1/2) nuclei (e.g., 14N, 35Cl, 49Ti, 65Cu, 91Zr); this latter category constitutes ca. 73% of the NMR-active nuclei in the periodic table. Many of these nuclei are classified as unreceptive, meaning that they are very challenging to study due to (i) low NMR frequencies, (ii) low natural abundance (iii) broad patterns arising from large anisotropic NMR interactions, (iv) inconvenient relaxation characteristics or (v) combinations thereof. My group utilizes SSNMR as the primary technique, along with X-ray diffraction and quantum chemical computations to solve a variety of problems. In particular, we work on development of methodologies to efficiently acquire SSNMR spectra of many of these nuclides, since they are so important in many areas of chemistry, biology and physics. We apply our new methodologies to study a variety of materials, including (1) heterogeneous catalysts used to produce polymers, (2) polypeptides, biopolymers and other biological molecules, and (3) solid pharmaceuticals and their polymorphs, which are distinct phases of a pure solid substance resulting from at least two differing arrangements of atoms. The last problem is particularly interesting, since we apply fundamental science to understand the relationship between NMR parameters and molecular structure, and use this to solve a problem of great relevance to the pharmaceutical industry and its consumers: i.e., how to differentiate polymorphs of pharmaceutical ingredients, so that we may understand what molecular interactions may lead to improved stability, shelf-life and bioavailability. In addition, each polymorph is patentable, so we may aid in the protection of intellectual property and valuable patents.