Capturing a new hydrate polymorph of amodiaquine dihydrochloride dihydrate via heterogeneous crystallisation

Herein, we report a new polymorph of amodiaquine dihydrochloride dihydrate obtained via heterogeneous crystallisation. This new polymorph exhibits similarity in molecular conformation as well as in its one-dimensional chain structure with a previously known polymorph, however with a difference in its two-dimensional sheet structure. Although crystal DFT-calculations predict the new form to be thermodynamically less stable compared to the previously known polymorph, the preparation method applied opened up the access to its metastable zone.