Synthesis of energetic coordination polymers based on 4-nitropyrazole by solid-melt crystallization in non-ionization condition

Based on the theory of crystallization, a solvent-free solid-liquid phase crystallization method called solid-melt crystallization was designed to prepare energetic coordination polymers. Two target compounds [Cu(NPyz)4NO3]·NO3 (ECPs-1) and Cu(NPyz)4(ClO4)2 (ECCs-2) were prepared through programmed heating and cooling by using 4-nitropyrazole (NPyz), (Cu(NO3)2·5H2O and Cu(ClO4)2·5H2O as raw materials. In addition, crystallization pre-experiments and annealing experiments also verified the feasibility of the method. Their structures were confirmed by IR, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction. The physicochemical properties and sensitivity test results showed that ECCs-2 has better thermal stability (Td = 221 °C), while ECPs-1 is less sensitive to mechanical stimuli (IS = 12 J, FS = 240 N). Calculations based on EXPLO5 and the Kamlet-Jacobs equation showed that ECCs-2 has more considerable detonation performance (P = 25.2 GPa, D = 7.5 km/s). In comparison, the more intuitive results from the HN test, flame test, thermal resistance test and lead plate explosion test revealed that ECCs-2 has an “ acceptable” detonation performance. The laser detonation test also showed that ECCs-2 is a promising excellent laser detonation material (E = 408 mJ, P = 24 W, τ = 17 ms).