Energetic multi-component molecular solids of tetrafluoroterephthalic acid with some aza compounds by strong hydrogen bonds and weak intermolecular interactions of C-H•••F and C-H•••O

Tetrafluoroterephthalic acid, (H(2)tfBDC), forms nine novel crystals with a series of N-containing heterocycles: 2,3-dimethyl pyrazine (2,3-Pyr), 2,6-dimethyl pyrazine (2,6-Pyr), 2,4-diamino-6-methyl-1,3,5-triazine (dmt), Benzoguanamine (bga), 2-methylbenzimidazole (2-MeBzlmH), 1,4-bis(imidazol) butane (bimb), 2-amino-4-hydroxy-6-methyl pyrimidine (ahmp), 1,2-bis[(2-methylimidazol-1-yl)methyl] benzene (L7), and 1,4-bis[(2-methylimidazol-1-yl) methyl] benzene (L5). These crystal structures including salts/co-crystals/hydrates were analyzed and characterized by single crystal X-ray diffraction, IR, and TGA. Single crystal X-ray diffraction studies show that the huge numbers of hydrogen bonds play a significance part in assembling individual molecules into larger architectures, especially the strong N-H center dot center dot center dot O, O-H center dot center dot center dot O hydrogen bonds, and weak but highly directional C-H center dot center dot center dot O and C-H center dot center dot center dot F interactions exist commonly in all nine novel crystals. Crystal structure analysis shows that the F atom of the H(2)tfBDC participates in C-H center dot center dot center dot F hydrogen bond formation, producing different supramolecular synthons. More importantly, the N-H center dot center dot center dot O, O-H center dot center dot center dot O, and C-H center dot center dot center dot O hydrogen bonds are mainly involved in the supramolecular assembly of these molecules, but C-H center dot center dot center dot F hydrogen bonds convert two-dimensional networks into three dimensional, hence, the C-H center dot center dot center dot F interactions have a crucial role in the formation of higher-order supramolecular structures.