Configuration flexibility of 2,5-bis(3-pyridyl)-1,3,4-oxadiazole in controllable cocrystallization with 3-hydroxybenzoic acid

Cocrystallization of 3-hydroxybenzoic acid (H2mba) with a versatile angular dipyridyl building block 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) under the ambient or hydrothermal condition affords, two binary molecular cocrystals [(H2mba)·(3-bpo)] (2) and [(H2mba)·(3-bpo)]·3.5H2O (3). X-ray single-crystal diffraction of 3-bpo (1) suggests that 1D infinite tape is formed via weak C-H⋯N interactions. With regard to pseudopolymorphs 2 and 3, similar 1D acid-base chains are generated through hard O-H⋯N hydrogen bonds, which however, adopt distinct 3D lattice packing. Significantly, three typical conformations of 3-bpo are observed in the structures of 1-3 to meet the requirements of the formation of different hydrogen-bonding patterns.