Synthesis and detonation performance of novel tetrazolyl-triazine nitrogen-rich energetic materials

The properties of energetic materials (EMs) are significantly influenced by specific features of their components and including multiple nitrogen-rich (N-rich) heterocycles within a single rigid framework is perhaps one of the most impactful and modern techniques employed in the design and development of novel high-performing explosives. In this regard, coupling tetrazole and s-triazine moieties is an attractive approach given their high nitrogen content and heats of formation resulting from the multiple N-N and/or C-N bonds in their frameworks. With this in mind, herein we report the synthesis of 2,4,6-tris(1H-tetrazol-5-yl)-1,3,5-triazine (H3TTT, 1), a new N-rich (73.7%) EM, along with a series of its salts (3-7). All compounds were physically characterized by IR, multinuclear (1H, 13C) NMR spectroscopy, gas pycnometry, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The molecular structure of the TTT3- moiety was confirmed through single-crystal X-ray diffraction (SCXRD) analysis of the triethylammonium (TEA) salt (2). Key energetic parameters were assessed, revealing neutral H3TTT (1) exhibits excellent thermal stability over 247 degrees C as confirmed through DSC studies, while the decomposition temperatures of the energetic salts (3-7) were found to be lower than the parent material 1 (Tdec ranges from 144 degrees C (7) to 217 degrees C (3)). In terms of detonation performance, the highest values were observed for 4 (Pdet = 24.8 GPa, Vdet = 8061 m s-1) and 5 (Pdet = 24.6 GPa, Vdet = 7984 m s-1), as well as for 1 (Pdet = 22.4 GPa, Vdet = 7430 m s-1), where all three outperform TNT (Pdet = 19.5 GPa; Vdet = 6881 m s-1). The results of the thermochemical calculations indicate that H3TTT (1) and its salts 4 and 5 are characterized by ballistic parameters comparable to those of the commonly used JA-2 propellant. By using this simple and straightforward approach to EM development, we have generated a series of materials that may be employed as green alternatives to TNT secondary explosives and low-erosion, environmentally benign high-nitrogen ingredients for gun-propellants. A novel N-rich (73.7%) energetic material, 2,4,6-tris(1H-tetrazol-5-yl)-1,3,5-triazine, along with a series of its salts were synthesized and physically characterized revealing excellent thermal stability and intriguing detonation parameters.