Energetic substances with layered crystal packing have been identified as the most promising next-generation high-energy materials (HEMs) due to their excellent insensitivity. The challenge, however, is how to design layered HEMs. In this study, a novel strategy called “acceptor–donor separation” was proposed to control the layer-by-layer stacking of energetic molecules through directional hydrogen boding: that is, a hydrogen bond donor and acceptor are located in different energetic segments and at least one of them has a conjugated planar structure, which will enable the energetic fragments to be infinitely extended in a two-dimensional plane to form a target layered structure. The experimental results showed that three exemplary substances designed by using this strategy possess the expected layered structures, which have been confirmed by single-crystal X-ray diffraction, demonstrating the robustness of this strategy. Moreover, the three as-synthesized HEMs all exhibit excellent insensitivity (impact sensitivity IS > 40 J; friction sensitivity FS > 360 N), affording safety far beyond those of the most powerful HEMs in use today. Especially, the hydroxylammonium energetic salts possess good detonation performance (detonation velocity D = 8924 m s–1; detonation pressure P = 36.9 GPa) comparable to that of 1,3,5-trinitro-1,3,5-triazine (RDX), one of the most powerful high explosives in use today.
The development of green energetic materials is based on environmental friendliness, safety and performance improvement. It is of great significance to design and synthesize new nitrogen rich salts for a new generation of green energetic materials. In the present work, a series of 3-amino-5-hydrazinopyrazole energetic salts comprising energetic anions were synthesized and were characterized using elemental analysis, IR spectroscopy and differential scanning calorimetry (DSC). Compounds 1–5 were further confirmed by single crystal X-ray diffraction and the sensitivities were measured by the standard BAM methods. Additionally, the structure–property relationship was elucidated from the experimental results and theoretical calculations. Energetic salts of 2 and 5 exhibited high heat of formation (5, 1160.06 kJ mol−1), high decomposition temperature (2, 172 °C; 5, 186 °C), excellent detonation performance (2, Dv, 9076 m s−1, P 34.1 GPa; 5, Dv, 8974 m s−1, P 31.9 GPa), moderate sensitivity towards outer stimuli and high nitrogen contents (2, 41.03%; 5, 63.84%). This work increases future prospects for the design of insensitive and novel high-energy green energetic material.