Enhancing NMR Sensitivity of Natural‐Abundance Low‐γ Nuclei by Ultrafast Magic‐Angle‐Spinning Solid‐State NMR Spectroscopy |
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| Authors: | Dr. Rongchun Zhang Yitian Chen Prof. Dr. Nair Rodriguez‐Hornedo Prof. Dr. Ayyalusamy Ramamoorthy |
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| Affiliation: | 1. Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan, USA;2. Department of Pharmaceutical Science, The University of Michigan, Ann Arbor, Michigan, USA |
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| Abstract: | Although magic‐angle‐spinning (MAS) solid‐state NMR spectroscopy has been able to provide piercing atomic‐level insights into the structure and dynamics of various solids, the poor sensitivity has limited its widespread application, especially when the sample amount is limited. Herein, we demonstrate the feasibility of acquiring high S/N ratio natural‐abundance 13C NMR spectrum of a small amount of sample (≈2.0 mg) by using multiple‐contact cross polarization (MCP) under ultrafast MAS. As shown by our data from pharmaceutical compounds, the signal enhancement achieved depends on the number of CP contacts employed within a single scan, which depends on the T1ρ of protons. The use of MCP for fast 2D 1H/13C heteronuclear correlation experiments is also demonstrated. The significant signal enhancement can be greatly beneficial for the atomic‐resolution characterization of many types of crystalline solids including polymorphic drugs and nanomaterials. |
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| Keywords: | cross-polarization NMR spectroscopy signal enhancement structure elucidation ultrafast MAS |
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