Acid–Base-Mediated Self-Assembly: Synthetic Access to High-Energy-Density Metal–Organic Frameworks and Host–Guest Energetic Materials

Abstract

Controlled condensed-state chemical reactions are critical for smart-material development. Reaction-driven self-assembly materials have been explored for decades across organic nanostructure, polymer, and biomaterial research. This strategy has recently enabled the design and synthesis of nitrogen-rich hydrogen-bonded organic frameworks and size-matched hydrogen-bonded hydroxylammonium frameworks. Nevertheless, energetic-material research lacks reports on tuning self-assembled structures of a single molecule via acid–base interactions. Herein, we present an acid–base-mediated, reaction-driven self-assembly strategy to fabricate the high-energy-density metal–organic framework KADNPP (potassium 2-((7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidine-2-carbonyl)oxy)) and host–guest energetic material HGEM-8. KADNPP displays an exceptionally high measured density of 2.238 g cm^–3 and remarkable thermal stability (T_d = 376 °C). Meanwhile, HGEM-8 possesses a high density of 1.940 g cm^–3 (single crystal X-ray diffraction: 1.982 g cm^–3), excellent detonation performance (D = 9464 m s^–1; P = 43.5 GPa), and superior solid-propellant performance (I_sp = 293 s, calculated by NASA CEA). These results demonstrate the significant potential of the present synthetic strategy for constructing high-energy-density self-assembled energetic materials.