Solid-state NMR of unreceptive nuclei

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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.