Fast-MAS solid-state NMR of efavirenz: Insights into spectral assignments and molecular asymmetry
- 1Interdisciplinary Institute of NMR and Molecular Sciences, Academy of Advanced Interdisciplinary Research, Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials, School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, China
Abstract
Solid-state nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for characterizing pharmaceutical solids, yet inconsistencies in spectral assignment can hinder accurate structural interpretation. In this study, we revisit the solid-state NMR of efavirenz (EFV), a widely used anti-HIV drug, by employing fast magic-angle spinning (MAS) at 37 kHz. Through a combination of one-dimensional (1H, 19F, 13C) and two-dimensional correlation (13C–1H and 13C–19F) experiments, we resolve previously disputed assignments. Critically, we correct the misassignment of the aromatic C3 and C4 resonances, which is unambiguously confirmed by a 2D 13C–1H correlation spectrum using the key HN–C4 proximity. The 19F spectrum reveals two distinct peaks with an integral ratio of 1:2, directly reflecting the three crystallographically independent molecules in the unit cell and offering a facile diagnostic for molecular asymmetry. 19F-detected 13C–19F correlations further differentiate carbon environments. This work not only rectifies prior assignment errors but also establishes a robust multinuclear approach, integrating 1H, 13C, and 19F NMR, for detailed analysis of fluorinated pharmaceuticals.
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BibTeX
@article{li2026fastmas,
title = {{Fast-MAS solid-state NMR of efavirenz: Insights into spectral assignments and molecular asymmetry}},
author = {Ziqian Li and Dina Wang and Hailu Zhang and Jun Yang and Zhengfeng Zhang},
journal = {Magnetic Resonance Letters},
year = {2026},
month = oct,
doi = {10.1016/j.mrl.2026.200310},
url = {https://doi.org/10.1016/j.mrl.2026.200310},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Fast-MAS solid-state NMR of efavirenz: Insights into spectral assignments and molecular asymmetry
AU - Ziqian Li
AU - Dina Wang
AU - Hailu Zhang
AU - Jun Yang
AU - Zhengfeng Zhang
PY - 2026
DA - 2026/10/13
JO - Magnetic Resonance Letters
DO - 10.1016/j.mrl.2026.200310
UR - https://doi.org/10.1016/j.mrl.2026.200310
AB - Solid-state nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for characterizing pharmaceutical solids, yet inconsistencies in spectral assignment can hinder accurate structural interpretation. In this study, we revisit the solid-state NMR of efavirenz (EFV), a widely used anti-HIV drug, by employing fast magic-angle spinning (MAS) at 37 kHz. Through a combination of one-dimensional (1H, 19F, 13C) and two-dimensional correlation (13C–1H and 13C–19F) experiments, we resolve previously disputed assignments. Critically, we correct the misassignment of the aromatic C3 and C4 resonances, which is unambiguously confirmed by a 2D 13C–1H correlation spectrum using the key HN–C4 proximity. The 19F spectrum reveals two distinct peaks with an integral ratio of 1:2, directly reflecting the three crystallographically independent molecules in the unit cell and offering a facile diagnostic for molecular asymmetry. 19F-detected 13C–19F correlations further differentiate carbon environments. This work not only rectifies prior assignment errors but also establishes a robust multinuclear approach, integrating 1H, 13C, and 19F NMR, for detailed analysis of fluorinated pharmaceuticals.
SN - 2097-0048
SN - 2772-5162
ER -