Syntheses and crystal structures of hydrated and anhydrous 1:2 cocrystals of oxyresveratrol and zwitterionic proline

The hydrated and anhydrous 1:2 cocrystals of oxyresveratrol (4-[(E)-2-(3,5-di­hydroxy­phen­yl)ethen­yl]benzene-1,3-diol; OXY; C14H12O4) and proline [(S)-pyrrolidine-2-carb­oxy­lic acid; PRO; C5H9NO2], namely, 4-[(E)-2-(3,5-di­hydroxy­phen­yl)ethen­yl]benzene-1,3-diol bis­[(S)-pyrrolidin-1-ium-2-carboxyl­ate] monohydrate, C14H12O4·2C5H9NO2·H2O, and the anhydrous form, C14H12O4·2C5H9NO2, were obtained by crystallization at different temperatures. Both of them crystallize with ortho­rhom­bic (P212121) symmetry. The structures display N—H⋯O and O—H⋯O hydrogen-bonding inter­actions between PRO and PRO, OXY and OXY, and OXY and PRO. In the hydrated cocrystal, these types of contacts are also observed between the OXY, PRO and water mol­ecules. A combination of these inter­actions leads to a three-dimensional supra­molecular assembly in each case. Hirshfeld surfaces were used to gain further insight into the inter­molecular inter­actions in the packing, including the relative percentage contributions of the significant inter­molecular H⋯H and H⋯O/O⋯H contacts.