Synthesis, thermal and spectroscopical properties of the cocrystal CL-20-MDNT

Abstract. Comparing different solvents applied in cooling and evaporation crystallization methods, ethyl acetate was found to be a suitable solvent for the crystallization of the cocrystal of Hexanitroisowurtzitan (C6H6N12O12)-Methyldinitrotriazol (C3H3N5O4) in the ratio 1:1. The cocrystal is a promising candidate for an explosive material with a detonation performance superior to Octogen and improved sensitivities compared to pure CL-20. A phase pure product was obtained with a density of 1.86 g/cm³ at ambient temperature. Raman spectra show a split of the signals attributed to the MDNT methyl group as well as shifts of 4-10 cm-1 for nitro group signals comparing pure MDNT with the cocrystal. Single crystal diffraction experiments confirmed space group P212121 for the crystal structure and offered input for further theoretical considerations. DSC measurements show a decomposition peak at 246 °C and a small endothermic signal at about 168 °C, linked with an irreversible phase transition and a reduction in volume, which is subject of investigations via in-situ diffraction and thermal analytic methods.