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A new symmetric compound 3,5-bis(3-amine-4H-1,2,4-triazole)-1H-pyrazole and a series of corresponding energetic salts 5–9 were synthesized. All the new compounds were fully characterized by spectroscopy (IR, NMR, and elemental) analyses and differential scanning calorimetry (DSC). Compound 6 was further investigated by X-ray crystal-structure analysis. Various performance tests of all the compounds, such as density, thermal behavior, mechanical sensitivity and detonation property, were tested. All the target compounds showed relatively positive calculated heat of formation (24.9 to 2396.4 kJ mol−1), good mechanical sensitivity (IS > 24 J, FS > 280 N) and acceptable detonation property (D > 7400 m s−1, P > 19.5 GPa). In particular, energetic salt 9 exhibits prominent detonation property (D > 8964 m s−1, P > 37.1 GPa) and excellent sensitivity (IS > 40 J, FS > 360 N), which show its potential application prospects as a new high energy insensitive material. [ABSTRACT FROM AUTHOR]

The intramolecular cyclization reaction of picrylhydrazone into an indazole derivative was systematically studied. The optimized conditions, mechanism and the generality of the cyclization reaction from picrylhydrazone to indazole were investigated. Picrylhydrazones 1a–6a and indazole derivatives 1b and 3b–7b were synthesized through a one-step reaction and the crystal structures of 2a, 4a and 5b were characterized by single crystal X-ray diffraction analysis. Among all the compounds, the indazole derivatives exhibit an increase of 24–341 m s−1 (0.3–4.3%), 0.6–3.1 GPa (2.2–14.3%) and 9–82 °C (5.0–44.0%) in detonation performance and thermal stability as well as a decrease of 4–10 J (15.4–33.3%) and 50–120 N (16.1–50.0%) in mechanical sensitivity to impact and friction compared with picrylhydrazones. Furthermore, the structure–property relationship was demonstrated by a combination of fingerprint plots, Hirshfeld surfaces and explosive properties. All those results demonstrated that this study can enrich the future prospects of the design of energetic materials. [ABSTRACT FROM AUTHOR]