A Novel Heat-Resistant Energetic Material: Pyrazolopyrimidine–Bistetrazole Compound

Nowadays, nitrogen-rich tetrazole is the key research object due to high heats of formation in energy materials, but low thermal stability limits its widely application. Herein, two tetrazole groups were introduced to the fused ring backbone to obtain pyrazolopyrimidine-bistetrazole compounds by the cyclization of amino-pyrazole and the cyclization of dicyano groups, resulting in a series of bistetrazole compounds <b>5</b>-<b>8</b>. All compounds exhibit superior overall performance (<i>T</i>_d = 292-313 °C, <i>D</i> = 7552-8414 m/s, IS = 28-32 J). Notably, compound <b>7</b> not only exhibits thermal stability (<i>T</i>_d = 313 °C) comparable to that of the traditional heat-resistant explosive HNS (<i>T</i>_d = 318 °C) but also possesses lower mechanical sensitivity (FS = 342 N, IS = 30 J) and superior detonation performance (<i>D</i> = 8414 m/s) compared to HNS (<i>D</i> = 7612 m/s, IS = 5 J), due to high nitrogen content and an extensive conjugated system. The structure-properties relationship was elucidated through theoretical calculations and experimental testing. The bistetrazole compound <b>7</b> with excellent performances shows great promise as a candidate material for a new generation of advanced heat-resistant explosive.