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Research data for "Testing the limits of NMR crystallography: the case of caffeine–citric acid hydrate" Open Access

The crystal structure of a new 1:2 caffeine-citric acid hydrate cocrystal is presented. The caffeine molecules are disordered over two positions, with the nature of the disorder confirmed to be static by 13C solid-state NMR. NMR linewidths in statically disordered systems reflect the distribution of local chemical environments, and this study investigates whether the disorder contribution to 13C linewidths can be predicted computationally. The limits of NMR crystallography calculations using density functional theory are tested by investigating how geometry optimisation conditions affect calculated NMR parameters. Careful optimisation is shown to reduce differences between 13C constants of symmetry-related sites to about 0.1 ppm. This is just sufficient to observe a correlation between calculated and experimental linewidths, and also show that systematic errors associated with geometry optimisation do not compromise other applications of “NMR crystallography”. In addition, the unit cell enthalpies calculated after careful optimisations provide insight into why the disordered structure is adopted.

Descriptions

Resource type

Dataset

Contributors

Creator: Kerr, Hannah E. ¹
Data collector: Kerr, Hannah E. ¹
Contact person: Hodgkinson, Paul ¹

¹ Durham University, UK

Funder

Research methods

Other description

Keyword

NMR crystallography
solid-state NMR
disorder
first-principles calculation
cocrystal

Subject

Crystallography
X-rays--Diffraction
Nuclear magnetic resonance spectroscopy

Location

Language

English

Cited in

doi:10.1039/c6ce01453d

Identifier

ark:/32150/r1np193917h
doi:10.15128/r1np193917h

Rights

Creative Commons Attribution 4.0 International (CC BY)

Publisher

Durham University

Date Created

2016-07-21

File Details

Depositor

P. Hodgkinson

Date Uploaded

26 July 2016, 11:07:55

Date Modified

27 July 2016, 12:07:32

Audit Status

Audits have not yet been run on this file.

Characterization

File format: zip (ZIP Format)

Mime type: application/zip

File size: 18179736

Last modified: 2016:07:26 12:14:09+01:00

Filename: CCA-databundle.zip

Original checksum: 1803464d14d2d30b5ab31f1eef9eb9f6