title: Potassium caffeate/caffeic acid co-crystal: the rat race between the catecholic and carboxylic moieties in an atypical co-crystal.
abstract: The vast literature concerning caffeic acid and its derivatives lacks any reference to the solid state structures of its inorganic salts as these crystals are quite difficult grow. Most of the already published works deal with computational studies of these compounds as well as investigations of their behaviour in solution. Having obtained good quality potassium caffeate/caffeic acid co-crystals, we solved their structure and used a robust approach, already applied to caffeic acid alone, to compare the X-ray structure with the one inferred by Molecular Dynamics (MD), focusing our attention on the structure-property relationships. The reliability of this method is confirmed by the overall agreement extended up to the anisotropic displacement parameters calculated, on one hand, by means of MD and the ones gathered, on the other hand, by X-ray measurements. Moreover, the lack of experimental evidence of an enthalpically favored polymorph, arising from the MD calculations, were explained on the basis of the Shannon's entropy.
authors.affiliation: Dipartimento di Scienze del Farmaco, Università degli Studi di Catania, Viale Andrea Doria 6, 95125, Catania, Italy.
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Lombardo
authors.forename: Gustavo
authors.initials: G
authors.lastname: Portalone
authors.forename: Ugo
authors.initials: U
authors.lastname: Chiacchio
authors.forename: Antonio
authors.initials: A
authors.lastname: Rescifina
authors.forename: Francesco
authors.initials: F
authors.lastname: Punzo
mesh_terms: D002109:Caffeic Acids / Q000737:chemistry*; D002396:Catechols / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D056004:Molecular Dynamics Simulation; D011188:Potassium / Q000737:chemistry*
chemical_list: D002109:Caffeic Acids; D002396:Catechols; D011188:Potassium; C040048:caffeic acid