| Autor: |
Hartman JD; Department of Chemistry, University of California , Riverside, California 92521 United States., Day GM; School of Chemistry, University of Southampton , Highfield, Southampton SO17 1BJ, United Kingdom., Beran GJ; Department of Chemistry, University of California , Riverside, California 92521 United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Crystal growth & design [Cryst Growth Des] 2016 Nov 02; Vol. 16 (11), pp. 6479-6493. Date of Electronic Publication: 2016 Oct 04. |
| DOI: |
10.1021/acs.cgd.6b01157 |
| Abstrakt: |
Chemical shift prediction plays an important role in the determination or validation of crystal structures with solid-state nuclear magnetic resonance (NMR) spectroscopy. One of the fundamental theoretical challenges lies in discriminating variations in chemical shifts resulting from different crystallographic environments. Fragment-based electronic structure methods provide an alternative to the widely used plane wave gauge-including projector augmented wave (GIPAW) density functional technique for chemical shift prediction. Fragment methods allow hybrid density functionals to be employed routinely in chemical shift prediction, and we have recently demonstrated appreciable improvements in the accuracy of the predicted shifts when using the hybrid PBE0 functional instead of generalized gradient approximation (GGA) functionals like PBE. Here, we investigate the solid-state 13 C and 15 N NMR spectra for multiple crystal forms of acetaminophen, phenobarbital, and testosterone. We demonstrate that the use of the hybrid density functional instead of a GGA provides both higher accuracy in the chemical shifts and increased discrimination among the different crystallographic environments. Finally, these results also provide compelling evidence for the transferability of the linear regression parameters mapping predicted chemical shieldings to chemical shifts that were derived in an earlier study. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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