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; C 14 H 12 O 4 ) and proline [( S )-pyrrolidine-2-carboxylic acid; PRO; C 5 H 9 NO 2 ], namely, 4-[( E )-2-(3,5-dihydroxyphenyl)ethenyl]benzene-1,3-diol bis[( S )-pyrrolidin-1-ium-2-carboxylate] monohydrate, C 14 H 12 O 4 ·2C 5 H 9 NO 2 ·H 2 O, and the anhydrous form, C 14 H 12 O 4 ·2C 5 H 9 NO 2 , were obtained by crystallization at different temperatures. Both of them crystallize with orthorhombic ( P 2 1 2 1 2 1 ) 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.