Acta Cryst. (2014). B70, 72-80 [ doi:10.1107/S2052520613033167 ]
Abstract: A polymorph screen on a new 1:1 co-crystal of caffeine, C8H10N4O2, with anthranilic acid, C7H7NO2, has revealed a rich diversity of crystal forms (two polymorphs, two hydrates and seven solvates, including two sets of isostructural solvates). These forms were prepared by liquid-assisted grinding and solution crystallization, and the crystal structures of nine of these forms have been solved using either single-crystal or powder X-ray data. The structures contain O-HN and N-HO hydrogen bonds through which caffeine and anthranilic acid molecules assemble to form zigzag-type chains. These chains can interact in an anti-parallel and offset manner to form cage- or channel-type skeletons within which solvent molecules can be located, giving rise to the diversity of forms observed for this co-crystal. In contrast, an equivalent series of liquid-assisted grinding and solution crystallization experiments with the closely related system of theobromine, C7H8N4O2, and anthranilic acid resulted in the formation of only one 1:1 co-crystal form.
CCDC references: 907851, 907852, 907853, 907855, 907856, 907857, 907858, 907859, 975719 and 975720
Keywords: co-crystals; polymorphism; solvates; hydrates.
Rietveld powder data file (CIF format) (270.8 kbytes)
Rietveld powder data file (CIF format) (273.1 kbytes)
Rietveld powder data file (CIF format) (101.7 kbytes)
Rietveld powder data file (CIF format) (68.5 kbytes)
Rietveld powder data file (CIF format) (49.7 kbytes)
To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.
The download button will force most browsers to prompt for a file name to store the data on your hard disk.
Where possible, images are represented by thumbnails.