Cocrystals of nutraceutical p-coumaric acid with caffeine and theophylline: Polymorphism and solid-state stability explored in detail using their crystal graphs

Article abstract of DOI:10.1039/c0ce00214c

Cocrystals constructed with p-coumaric acid (a phytochemical and nutraceutical compound) are investigated with xanthine compounds, caffeine and theophylline. Four cocrystals of p-coumaric acid with caffeine (1:1 and 1:2 stoichiometric ratios) and theophylline (two 1:1 polymorphs, Form I and Form II) were generated and their structures determined by single-crystal X-ray crystallography. The two theophylline cocrystals display synthon polymorphism, where both structures possess a carboxylic acid-imidazole heteromeric synthon; however, one polymorph also has a hydroxyl-carbonyl synthon (Form I), while in the other a hydroxyl-imidazole synthon (Form II) is present. Furthermore, the solid-state stability of the two p-coumaric acid:theophylline polymorphs was explored experimentally and computationally.