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?

CrystEngComm Pub Date: 2014-02-17 DOI: 10.1039/C4CE00133H

Abstract

Tetrafluoroterephthalic acid, (H2tfBDC), 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?O, O–H?O hydrogen bonds, and weak but highly directional C–H?O and C–H?F interactions exist commonly in all nine novel crystals. Crystal structure analysis shows that the F atom of the H2tfBDC participates in C–H?F hydrogen bond formation, producing different supramolecular synthons. More importantly, the N–H?O, O–H?O, and C–H?O hydrogen bonds are mainly involved in the supramolecular assembly of these molecules, but C–H?F hydrogen bonds convert two-dimensional networks into three dimensional, hence, the C–H?F interactions have a crucial role in the formation of higher-order supramolecular structures.

Graphical abstract: 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
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