Containment of Polynitroaromatic Compounds in a Hydrogen Bonded Triarylbenzene Host

Abstract

Co-crystallization of energetic materials has emerged as an important technique to modify their critical properties such as stability, sensitivity, etc. Using 1,3,5-tris­(4′-aminophenyl)­benzene (TAPB) as a novel co-crystal former, we have prepared co-crystals of 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), and <i>m</i>-dinitrobenzene (<i>m</i>DNB). Molecular structures of the co-crystals have been determined from single crystal X-ray diffraction data. The diffraction data analysis reveals that strong intermolecular π–π interaction directs the intercalation of polynitroaromatic explosives (PNACs) between the layers of TAPB molecules, which leads to the formation of vertically overlapped -A-B-A-B- types of π-stacks. Both TNT and TNP form π-interactions with the center of TAPB with 1:1 molar ratios, while <i>m</i>DNB forms a complex in a 1:3 stoichiometry through stacking between peripheral rings. The crystal lattices are further stabilized through interstack hydrogen bonds (N–H···N and N–H···O) between amino groups of TAPB and nitro groups of PNACs. NMR and Fourier transform infrared spectra further provide the information about the presence of various interactions in the crystal systems. Owing to the π electron-rich nature and ease of synthesis, triphenylbenzene systems are promising host candidates for co-crystallization of PNAC analytes