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A 13 C solid‐state NMR analysis of steroid compounds
Author(s) -
Yang JenHsien,
Ho Yu,
Tzou DerLii M.
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2235
Subject(s) - chemistry , steroid , singlet state , nuclear magnetic resonance spectroscopy , crystallography , nmr spectra database , stereochemistry , spectroscopy , solid state , chemical shift , crystal structure , spectral line , biochemistry , physics , quantum mechanics , astronomy , hormone , nuclear physics , excited state
13 C CP/MAS solid‐state NMR spectroscopy has been utilized to analyze six steroid compounds, namely testosterone (Tes), hydrocortisone (Cor), trans ‐dehydroandrosterone (Adr), prednisolone (Prd), prednisone (Pre) and estradiol (Est). Among them, Tes displays a doublet pattern for all residues, whereas Prd, Pre and Est, exhibit exclusively singlets . For Cor and Adr, the 13 C spectra contain both doublet and singlet patterns. The 13 C doublet signal, with splittings of 0.2–1.5 ppm, are ascribed to local differences in the ring conformations associated with polymorphism. We have assigned all of the 13 C resonances to the different residues in these steroid compounds on the basis of solution NMR data. The C‐7, C‐8, C‐10, C‐15 and C‐16 residues of Tes, Cor and Adr consistently give rise to singlets or doublets with splittings of less than 0.5 ppm, indicating similar local conformations. Accompanying hydration and dehydration processes, a reversible phase transformation between δ‐ and α‐crystal forms has been observed in Tes, corresponding to singlet and doublet 13 C patterns, respectively. To further characterize the ring conformations in the α‐form, we have successfully extracted chemical shift tensor elements for the 13 C doublets . It is demonstrated that 13 C solid‐state NMR spectroscopy provides a reliable and sensitive means of characterizing polymorphism in steroids. Copyright © 2008 John Wiley & Sons, Ltd.