Prof Gordon Wallace, Prof Maria Forsyth, Prof Douglas MacFarlane, Prof David Officer, Prof Mark Cook, Prof Susan Dodds, Prof Geoffrey Spinks, Prof Gursel Alici, A/Prof Simon Moulton, A/Prof Marc in het Panhuis, A/Prof Robert Kapsa, A/Prof Jeremy Crook, A/Prof Peter Innis, Dr Attila Mozer, Dr Michael Higgins, Prof Michelle Coote, Prof Xungai Wang, A/Prof Patrick Howlett, A/Prof Jenny Pringle, Prof Linda Hancock, Prof Leone Spiccia, Dr Jie Zhang, A/Prof Robert Sparrow, Prof Brett Paull, A/Prof Dirk Guldi, Prof Masayoshi Watanabe, A/Prof Seon-Jeong Kim, Prof Dermot Diamond, Prof Patrick Unwin, Dr Millicent Firestone
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 – 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 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.