Characterization of Polymorphs and Solid-State Reactions for Paramagnetic Systems by 13C Solid-State NMR and ab Initio Calculations
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- 作者：Medhat A. Shaibat ; Leah B. Casabianca ; Nalinda P. Wickramasinghe ; Stephen Guggenheim ; Angel C. de Dios ; Yoshitaka Ishii
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：September 12, 2007
- 年：2007
- 卷：129
- 期：36
- 页码：10968 - 10969
- 全文大小：57K
- 年卷期：v.129,no.36(September 12, 2007)
- ISSN：1520-5126
文摘
Despite its importance in drug and material science, spectroscopic characterization of polymorphs or supramolecular structures of paramagnetic systems often poses challenges, particularly for noncrystalline solids. This work demonstrates that 13C solid-state NMR (SSNMR) of paramagnetic systems under very fast magic angle spinning (VFMAS) (spinning speed of 20 kHz or higher) provides exceptionally sensitive means to probe small structural difference among polymorphs of paramagnetic complexes in noncrystalline solids, including drugs and materials containing paramagnetic metal ions. 13C VFMAS SSNMR experiments and corresponding ab initio shift calculations for Cu(II)(8-quilinolinol)2, anticancer agents, show that 
- and 
-forms of this compound can be easily distinguished by notable difference in paramagnetic relaxation times and hyperfine shifts. It is also shown that applications of the present technique allow for quantitative and chemical characterization of solid-state reactions for Cu(8-quilinolinol)2 and Cu(imidazole)2 in a noninvasive manner.
- and -forms of this compound can be easily distinguished by notable difference in paramagnetic relaxation times and hyperfine shifts. It is also shown that applications of the present technique allow for quantitative and chemical characterization of solid-state reactions for Cu(8-quilinolinol)2 and Cu(imidazole)2 in a noninvasive manner.