Seven cocrystals of pyrazinamide and organic acids by H-bonds and some noncovalent associations

• Seven cocrystals have been prepared and structurally characterized. • H-bonds have been ascertained. • The classical H-bonds are the key forces. • Secondary interactions also play important role. Pyrazinamide, (PZA), forms seven novel co-crystals with a series of organic acids: 2‑chloro-4-nitrophenol (cnp), o‑hydroxy-cinnamic acid (ohcina), p‑hydroxy-cinnamic acid (phcina), 4-hydroxymandelic acid (hmna), 2,6-dichlorobenzoic acid (dcba), 5-hydroxyisophthalic acid (hispta) and 2,5-thiophenedicarboxylic acid (tpda). These crystal structures were analyzed and characterized by mp, single crystal X-ray diffraction, and IR. Single crystal X-ray diffractions show that the classical hydrogen bonds play a key part in binding individual molecules into larger architectures, especially the strong N H···N, N H···O, O H···N and O H···O hydrogen bonds, weak but highly directional C H···O interactions exist commonly in all co-crystals. Deep view into the crystal packing unveil that a different array of additional CH N, CH O, CH-π, CH CH, CH Cl, C C, O C, N-S, Cl-O, Cl-Cl and π-π contacts contribute to the stabilization and expansion of the total 3D nets. For the delicate balance of the various weak forces, these structures adopted homo or hetero supramolecular synthons or both. Particularly, apart from 1 , all of the reported co-crystals share the widely common R 2 2 (8) synthon.