Regulating the Thermal Stability and Energy of Fused-Ring Energetic Materials by Hydrazo Bridging and Hydrogen-Bonding Networks

Inthis work, a combined strategy of bridging two tetrazolo[1,5-b]pyridazine rings and introducing intramolecular hydrogenbonds (N-H center dot center dot center dot O) with a hydrazo group was developedto construct a new high-energy and heat-resistant energetic compoundnamed 6,6 '-hydrazo-bis(8-amino-7-nitrotetrazolo[1,5-b]pyridazine) (1). Its dehydrogenated derivative6,6 '-azo-bis(8-amino-7-nitrotetrazolo[1,5-b]pyridazine) (2), which had fewer intramolecular hydrogenbonds (N-H center dot center dot center dot O), was also synthesized for comparison.Compounds 1 and 2 were characterized byhigh-resolution mass spectrometry, nuclear magnetic resonance, single-crystalX-ray diffraction, infrared spectroscopy, and elemental analysis.Their properties, such as densities (rho: 1.87 g center dot cm(-3) for 1, 1.77 g center dot cm(-3) for 2), heat of formation values (Delta H (f): 1079 kJ center dot mol(-1) for 1,1235 kJ center dot mol(-1) for 2), detonationvelocities (D (v): 9064 m center dot s(-1) for 1, 8429 m center dot s(-1) for 2), detonation pressures (P: 35.2 GPa for 1, 27.8 GPa for 2), decomposition temperatures(T (d): 292 degrees C for 1, 260 degrees C for 2), impact sensitivities (IS: 16 J for 1, 4 J for 2), and friction sensitivities (FS:>360 N for 1, 160 N for 2), were tested.These results suggest that compound 1 is a promisinghigh-energy and thermally stable energetic material. A combined strategy of hydrazo bridgingand hydrogen-bondingnetwork was developed to construct new high-energy and thermally stableenergetic materials.