C6N10O4: Thermally Stable Nitrogen-Rich Inner Bis(diazonium) Zwitterions

Zwitterionic Energetic Materials: Synthesis, Structural Diversity and Energetic Properties

Zwitterionic compounds are an emergent class of energetic materials and have gained synthetic interest of many in the recent years. Due to their better packing efficiencies and strong inter/intramolecular electrostatic interactions, they often ensue superior energetic properties than their salt analogues. A systematic review from the perspective of design, synthesis, and physicochemical properties evaluation of the zwitterionic energetic materials is presented. Depending on the parent ring(s) used for the synthesis and the type of moieties bearing positive and negative charges, different classes of energetic materials, such as primary explosives, secondary explosives, heat resistant explosives, oxidizers, etc., may result. The properties of some of the energetic zwitterionic compounds are also compared with analogous energetic salts. This review will encourage readers to explore the possibility of designing new zwitterionic energetic materials.

Solvent Free Potassium 3,5-dinitro-6-oxo-1,6-dihydropyrazin-2-olate 3D EMOF as Thermally Stable Energetic Material

Heat-resistant explosives play a vital role in indispensable applications. For this, we have synthesized a novel, three-dimensional, solvent-free energetic metal-organic framework (EMOF) potassium 3,5-dinitro-6-oxo-1,6-dihydropyrazin-2-olate (KDNODP) straightforwardly. The synthesized EMOF was characterized through IR, NMR spectroscopy, elemental analysis, and differential scanning calorimetry studies. Furthermore, single-crystal X-ray diffraction provided a complete description of KDNODP. It exhibits a three-dimensional EMOF structure with remarkably balanced properties such as high density (2.11 g cm-3), excellent thermal stability (291 °C), good detonation performance (8127 m s-1 and 26.94 GPa) and low mechanical sensitivity (IS=35 J; FS=360 N) than the commonly used heat-resistant explosives HNS (density=1.74 g cm-3; VOD=7164 m s-1, DP=21.65 GPa, IS=5 J) as well as the similar reported energetic potassium MOFs. To gain insights into the packing and intermolecular interactions, the Hirshfeld surface and a 2D fingerprint analysis were examined. Additionally, scanning electron microscopy was used to investigate the particle size and morphological characteristics of KDNODP. These outcomes highlight a successful method for creating 3D EMOF based on a six-membered heterocycle as a potential heat-resistant energetic material.

High-performing, insensitive and thermally stable energetic materials from zwitterionic gem-dinitromethyl substituted C-C bonded 1,2,4-triazole and 1,3,4-oxadiazole

A series of gem-dinitromethyl substituted zwitterionic C-C bonded azole based energetic materials (3-8) were designed, synthesized, and characterized through NMR, IR, EA, and DSC studies. Further, the structure of 5 was confirmed with SCXRD and those of 6 and 8 with ¹⁵N NMR. All the newly synthesized energetic molecules exhibited higher density, good thermal stability, excellent detonation performance, and low mechanical sensitivity to external stimuli such as impact and friction. Among all, compounds 6 and 7 may serve as ideal secondary high energy density materials due to their remarkable thermal decomposition (200 °C and 186 °C), insensitivity to impact (>30 J), velocity of detonation (9248 m s^-1 and 8861 m s^-1) and pressure (32.7 GPa and 32.1 GPa). Additionally, the melting and decomposition temperatures of 3 (T_m = 92 °C, T_d = 242 °C) indicate that it can be used as a melt-cast explosive. The novelty, synthetic feasibility, and energetic performance of all the molecules suggest that they can be used as potential secondary explosives in defence and civilian fields.

Chemical Descriptors for a Large-Scale Study on Drop-Weight Impact Sensitivity of High Explosives

The drop-weight impact test is an experiment that has been used for nearly 80 years to evaluate handling sensitivity of high explosives. Although the results of this test are known to have large statistical uncertainties, it is one of the most common tests due to its accessibility and modest material requirements. In this paper, we compile a large data set of drop-weight impact sensitivity test results (mainly performed at Los Alamos National Laboratory), along with a compendium of molecular and chemical descriptors for the explosives under test. These data consist of over 500 unique explosives, over 1000 repeat tests, and over 100 descriptors, for a total of about 1500 observations. We use random forest methods to estimate a model of explosive handling sensitivity as a function of chemical and molecular properties of the explosives under test. Our model predicts well across a wide range of explosive types, spanning a broad range of explosive performance and sensitivity. We find that properties related to explosive performance, such as heat of explosion, oxygen balance, and functional group, are highly predictive of explosive handling sensitivity. Yet, models that omit many of these properties still perform well. Our results suggest that there is not one or even several factors that explain explosive handling sensitivity, but that there are many complex, interrelated effects at play.

Imidazole-Based Energetic Materials: A Promising Family of N-Heterocyclic Framework

Imidazole represents a fascinating class of explosophoric units with exciting structures and unique properties. As compared to other nitrogen-rich heterocycles, imidazole demonstrates great potential applications due to economic effectiveness and superior energetic performances. The field of traditional chemistry has been extensively explored for imidazole, and thus established bond-building methods and functionalization strategies promote further development as high-energy density materials (HEDMs). This review addresses the development of energetic imidazole compounds in the past decade, summarizes their physiochemical properties, and is divided into three parts (explosives, propellants, and energetic biocides) according to application requirements. Various synthetic strategies for these energetic molecules are highlighted, including the construction of heterocyclic frameworks and following functionalization. The selected and discussed reactions illustrate the versatility of imidazole in energetic applications as building blocks for the future design of new HEDMs.

Novel polynitro azoxypyrazole-based energetic materials with high performance

Novel polynitro azoxypyrazole-based energetic compounds 1,2-bis (4-nitro-1H-pyrazol-5-yl) diazene 1-oxide (3) and 1,2-bis (1,4-dinitro-1H-pyrazol-3-yl) diazene 1-oxide (4) were synthesized from 5-amino-pyrazole-4-carbonitrile by optimized reactions. Their structures were characterized by elemental analysis and single-crystal X-ray diffraction techniques. Compound 3 exhibits high thermal stability (239 °C), low mechanical sensitivity (IS = 22 J, FS = 240 N) and moderate detonation performance (D_v = 8272 m s^-1, P = 28.1 GPa). Compound 4 shows moderate thermal stability (161 °C), decent mechanical sensitivity and higher detonation performance (D_v = 9228 m s^-1, P = 38.7 GPa) compared to that of RDX. These newly developed strategies for constructing novel energetic compounds enrich the content of the ever-expanding energetic materials.

Surface functionalization of nanomaterials by aryl diazonium salts for biomedical sciences

Nanoparticles (NPs) can be prepared by simple reactions and methods from a number of materials. Their small size opens up a number of applications in different fields, among which biomedicine, including: i) drug delivery, ii) biosensors, iii) bioimaging, iv) antibacterial activity. To be able to perform such tasks, NPs must be modified with a variety of functional molecules, such as drugs, targeting groups, chemical tags or antibacterial agents, and must also be prevented from aggregation. The attachment must be stable to resist during the transportation to the targeted location. Diazonium salts, which have been widely used for coupling applications and surface modification, fulfil such criteria. Moreover, they are simple to prepare and can be easily substituted with a large number of organic groups. This review describes the use of these compounds in nanomedicine with a focus on the construction of nanohybrids derived from metal, oxide and carbon-based NPs as well as viruses.

Boosting intermolecular interactions of fused cyclic explosives: the way to thermostable and insensitive energetic materials with high density

Improving the packing efficiency of explosives by strong intermolecular interactions can acquire high density while avoiding the expense of stability.

Laser ignition of energetic complexes: impact of metal ion on laser initiation ability

Alkali metal-containing energetic complexes were easy to initiate, followed by the free ligand, whereas the alkaline-earth metal complexes exhibited longer initiation delay times.

Combination of gem-dinitromethyl functionality and a 5-amino-1,3,4-oxadiazole framework for zwitterionic energetic materials

A series of zwitterionic energetic materials was reported, which exhibited higher densities and better detonation performances than common energetic salts.