Energetic Metal-Organic Frameworks Incorporating NH3OH+ for New High-Energy-Density Materials.

Energetic metal-organic frameworks (E-MOFs) have witnessed increasing development over the past several years. However, as a highly energetic cation, NH3OH+ has never been explored to construct transition-metal-based E-MOFs. Herein, we report the first examples of NH3OH+-containing E-MOFs with bis(tetrazole)methane (H2btm) as a ligand and copper and manganese as central metal ions, [(NH3OH)2(Cu(btm)2)]n and [(NH3OH)2(Mn(btm)2)]n. Crystal structure determinations reveal that both E-MOFs show two-dimensional layered structures. Experimental results suggest that they have high thermal decomposition temperatures (>200 °C). Among them, Cu-based E-MOFs possesses outstanding thermal stability (Tdec = 230.3 °C), which surpasses those of known NH3OH+-containing compounds. They also have high energy density; in particular, the Cu-based E-MOF affords a high heat of combustion (11447 kJ kg-1) and high heat of detonation (713.8 kJ mol-1) beyond the most powerful organic explosives in use today. Additionally, the two E-MOFs show completely different sensitivity properties: the Mn-based E-MOF is an insensitive high-energy-density material (IS > 40 J; FS > 360 N; EDS > 20 J), while the Cu-based E-MOF can be classified as a sensitive energetic material (IS = 13 J; FS = 216 N; EDS = 10.25 J), demonstrating their diverse applications in different fields. Our research proposes a unique class of high-energy-density materials.

A green metal-free fused-ring initiating substance.

Over the past century, the search for lead-free, environmentally friendly initiating substances has been a highly challenging task in the field of energetic materials. Here, an organic primary explosive featuring a fused-ring structure, 6-nitro-7-azido-pyrazol[3,4-d][1,2,3]triazine-2-oxide, was designed and synthesized through a facile two-step reaction from commercially available reagents. This organic initiating substance meets nearly all of the stringent criteria of environmentally friendly primary explosives for commercial applications: it is free of toxic metals and perchlorate, has a high density, high priming ability, unusual sensitivities towards non-explosive stimuli, excellent environmental resistance, decent thermal stability, high detonation performance, satisfactory flowability and pressure durability, and is low-cost and easy to scale-up. These combined properties and performance measures surpass the current and widely used organic primary explosive, DDNP. The fused-ring organic primary explosive reported herein may find real-world application as an initiating explosive device in the near future.

Designing Explosive Poly(Ionic Liquid)s as Novel Energetic Polymers.

The development of ionic-liquid-derived functional materials would be vital for stimulation of the interdisciplinary research in the fields of ionic liquid chemistry and material science. Here, a series of novel poly(ionic liquid)s with explosive capability were designed and prepared by introducing the energetic nitrato group and nitro-rich anions, such as nitrate, dinitramide, and nitroform into the polymeric chains. The as-synthesized explosive poly(ionic liquid)s (E-PILs) were fully characterized, and their physicochemical and detonation properties were investigated. All E-PILs show higher detonation performances than state-of-the-art energetic polymers including glycidyl azide polymer (GAP) and poly(glycidyl nitrate) [poly(GLYN)]. Some E-PILs exhibit higher calculated detonation velocities and pressures than 2,4,6-trinitrotoluene (TNT). These E-PILs are promising candidates for applications as new high-performance energetic polymers.

A promising high-energy-density material.

High-energy density materials represent a significant class of advanced materials and have been the focus of energetic materials community. The main challenge in this field is to design and synthesize energetic compounds with a highest possible density and a maximum possible chemical stability. Here we show an energetic compound, [2,2'-bi(1,3,4-oxadiazole)]-5,5'-dinitramide, is synthesized through a two-step reaction from commercially available reagents. It exhibits a surprisingly high density (1.99 g cm-3 at 298 K), poor solubility in water and most organic solvents, decent thermal stability, a positive heat of formation and excellent detonation properties. The solid-state structural features of the synthesized compound are also investigated via X-ray diffraction and several theoretical techniques. The energetic and sensitivity properties of the explosive compound are similar to those of 2, 4, 6, 8, 10, 12-(hexanitrohexaaza)cyclododecane (CL-20), and the developed compound shows a great promise for potential applications as a high-energy density material.High energy density materials are of interest, but density is the limiting factor for many organic compounds. Here the authors show the formation of a high density energetic compound from a two-step reaction between commercially available compounds that exhibit good heat thermal stability and detonation properties.