Study of Physicochemical and Explosive Properties of a 2,4,6-Trinitrotoluene/Aniline Cocrystal Solvate

Abstract

In the development of crystal engineering and supramolecular chemistry, cocrystallization has been used as a way to develop novel explosives with tailored properties. We present a novel cocrystal solvate composed of 2,4,6trinitrotoluene (TNT) and aniline that exhibits unique physicochemical and explosive properties. X-ray diffraction studies reveal the crystallographic structure to contain TNT and aniline in a 1:1 molecular ratio. The crystals themselves exhibit a vibrant, ruby red color that likely results due to a charge-transfer interaction between the overlapping π-orbitals of the aromatic rings. The most notable evidence for a chargetransfer complex is the appearance of a broad absorbance peak in the visible region which is not present in the spectrum of either pure component. Comparisons of the cocrystal solvate to that of pure TNT are conducted to determine thermodynamic and kinetic parameters using both experimental and theoretical techniques. The desolvation of aniline from the cocrystal solvate was also investigated using both in situ powder X-ray diffraction and atomic force microscopy measurements to monitor changes in the crystal structure and surface topography, respectively.

Effects of Solution Conditions on Polymorph Development in 2,4,6-Trinitrotoluene

“…Note: Aniline was also investigated as one of the solvents to be included in this study, but, rather than a pure TNT polymorph, a cocrystal solvate with a red appearance was found to form between the two. These results have been reported elsewhere …”

“…The polymorphs obtained from all temperature combinations of the respective (polar) solvent and water (the antisolvent) are shown in Table . In addition to these results, toluene and benzene (and aniline) were the only nonpolar solvents in which TNT crystals were successfully precipitated from using hexanes as the antisolvent. In both nonpolar solvent cases, the TNT crystals were determined to be orthorhombic which differs from the monoclinic polymorphism obtained using solvent evaporation (Table ) in these two solvents.…”

“…These results have been reported elsewhere. 44 Crystallization was induced after pipetting water atop the surface of the respective TNT solution. Furthermore, the temperature of each liquid upon mixing was varied.…”