3,3′-Dinitroamino-4,4′-azoxyfurazan and Its Derivatives: An Assembly of Diverse N–O Building Blocks for High-Performance Energetic Materials

On the basis of a design strategy that results in the assembly of diverse N–O building blocks leading to energetic materials, 3,3′-dinitroamino-4,4′-azoxyfurazan and its nitrogen-rich salts were obtained and fully characterized via spectral and elemental analyses. Oxone (potassium peroxomonosulfate) is an efficient oxidizing agent for introducing the azoxy N-oxide functionality into the furazan backbone, giving a straightforward and low-cost synthetic route. On the basis of heats of formation calculated with Gaussian 03 and combined with experimentally determined densities, energetic properties (detonation velocity, pressure and specific impulse) were obtained using the EXPLO v6.01 program. These new molecules exhibit high density, moderate to good thermal stability, acceptable impact and friction sensitivities, and excellent detonation properties, which suggest potential applications as energetic materials. Interestingly, 3,3′-dinitroamino-4,4′-azoxyfurazan (4) has the highest calculated crystal density of 2.02 g cm–3 at 173 K (gas pycnometer measured density is 1.96 g cm–3 at 298 K) for N-oxide energetic compounds yet reported. Another promising compound is the hydroxylammonium salt (6), which has four different kinds of N–O moieties and a detonation performance superior to those of 1,3,5,7-tetranitrotetraazacyclooctane (HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclododecane (CL-20). Furthermore, computational results, viz., NBO charges and ESP, also support the superior qualities of the newly prepared compounds and the design strategy.本研究基于组装多样N-O结构单元以制备含能材料的设计策略，成功合成了3,3'-二硝氨基-4,4'-氧化偶氮呋咱（3,3′-dinitroamino-4,4′-azoxyfurazan）及其富氮盐，并通过光谱分析与元素分析对其进行了全面表征。过一硫酸氢钾复合盐（Oxone, potassium peroxomonosulfate）是一种高效氧化剂，可将氧化偶氮N-氧官能团引入呋咱骨架，为目标产物提供了一条简便且低成本的合成路径。基于Gaussian 03软件计算得到的生成焓，结合实验测得的密度，本研究通过EXPLO v6.01程序计算得到了目标化合物的含能性能，包括爆速、爆压与比冲。这类新型化合物展现出高晶体密度、中等至优异的热稳定性、可接受的撞击与摩擦感度，以及优异的爆轰性能，具备作为含能材料的应用潜力。值得注意的是，3,3'-二硝氨基-4,4'-氧化偶氮呋咱（3,3′-dinitroamino-4,4′-azoxyfurazan，化合物4）在173 K下的理论计算晶体密度可达2.02 g·cm⁻³，为目前已报道的N-氧代含能化合物中最高者（298 K下气体比重瓶实测密度为1.96 g·cm⁻³）。另一款颇具应用前景的化合物为羟胺盐（hydroxylammonium salt，化合物6），其含有四种不同的N-O官能团，爆轰性能优于奥克托今（1,3,5,7-四硝基四氮杂环辛烷，HMX）与六硝基六氮杂异伍兹烷（2,4,6,8,10,12-六硝基-2,4,6,8,10,12-六氮杂四环十二烷，CL-20）。此外，自然键轨道（NBO, Natural Bond Orbital）电荷与静电势（ESP, Electrostatic Potential）等计算结果，也进一步佐证了新型合成化合物及本设计策略的优异性能。