Combining X-ray and NMR Crystallography to Explore the Crystallographic Disorder in Salbutamol Oxalate
| Autor: | Aneesa J. Al-Ani, Patrick M. J. Szell, Zainab Rehman, Helen Blade, Helen P. Wheatcroft, Leslie P. Hughes, Steven P. Brown, Chick C. Wilson |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Crystal Growth & Design. 22:4696-4707 |
| ISSN: | 1528-7505 1528-7483 |
| DOI: | 10.1021/acs.cgd.1c01093 |
| Popis: | Salbutamol is an active pharmaceutical ingredient commonly used to treat respiratory distress, and is listed by the World Health Organization as an essential medicine. Here, we establish the crystal structure of its oxalate form, salbutamol oxalate, and explore the nature of its crystallographic disorder by combined X-ray crystallography and 13 C cross-polarization (CP) magic-angle spinning (MAS) solid-state NMR. The *C-OH chiral center of salbutamol (note that the crystal structures are a racemic mixture of the two enantiomers of salbutamol) is disordered over two positions, and the tert-butyl group is rotating rapidly, as revealed by 13 C solid-state NMR. The impact of crystallisation conditions on the disorder was investigated, finding variations in the occupancy ratio of the *C-OH chiral center between single crystals, and a consistency across samples in the bulk powder. Overall, this work highlights the contrast between investigating crystallographic disorder by X-ray diffraction, solid-state NMR crystallography, and gauge-including projector augmented wave (GIPAW) DFT calculations, with their combined use yielding an improved understanding of the nature of the crystallographic disorder between the local (i.e., as viewed by NMR) and the longer-range periodic (i.e., as viewed by diffraction) scale. |
| Databáze: | OpenAIRE |
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