How Many Molecules Can You Crystallize From One Experiment? Chalcone-Flavanone Isomerization in a Beaker

Michelle Duong, Vassar College ’12 and Prof.Miriam Rossi and Dr. Francesco Caruso, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Rome, Italy

Chalcones, flavones and flavanones are naturally occurring compounds from plants with a wide range of biological activities. We are interested in studying the molecular structures using X-ray diffraction of these compounds so that a correlation between the chemical structure and the biological activities may be seen. The crystallization of C16 H14 O5, 3-methoxy-4,2’,5’-trihydroxyxchalcone from a mixture of ethanol-water produced three different types of crystals which were visually different. We report the results of these 3 crystal structure determinations that show, respectively, the chalcone and the flavanone isomers and a third structure showing the conformational disorder of the isomerization equilibrium between the flavanone and the chalcone molecular structure!