High-Density Energetic Metal–Organic Frameworks Based on the 5,5′-Dinitro-2H,2′H-3,3′-bi-1,2,4-triazole

Abstract

High-energy metal–organic frameworks (MOFs) based on nitrogen-rich ligands are an emerging class of explosives, and density is one of the positive factors that can influence the performance of energetic materials. Thus, it is important to design and synthesize high-density energetic MOFs. In the present work, hydrothermal reactions of Cu(II) with the rigid polynitro heterocyclic ligands 5,5′-dinitro-2H,2′H-3,3′-bi-1,2,4-triazole (DNBT) and 5,5′-dinitro-3,3′-bis-1,2,4-triazole-1-diol (DNBTO) gave two high-density MOFs: [Cu(DNBT)(ATRZ)3]n (1) and [Cu(DNBTO)(ATRZ)2(H2O)2]n (2), where ATRZ represents 4,4′-azo-1,2,4-triazole. The structures were characterized by infrared spectroscopy, elemental analysis, ultraviolet-visible (UV) absorption spectroscopy and single-crystal X-ray diffraction. Their thermal stabilities were also determined by thermogravimetric/differential scanning calorimetry analysis (TG/DSC). The results revealed that complex 1 has a two-dimensional porous framework that possesses the most stable chair conformations (like cyclohexane), whereas complex 2 has a one-dimensional polymeric structure. Compared with previously reported MOFs based on copper ions, the complexes have higher density (ρ = 1.93 g cm−3 for complex 1 and ρ = 1.96 g cm−3 for complex 2) and high thermal stability (decomposition temperatures of 323 °C for complex 1 and 333.3 °C for complex 2), especially because of the introduction of an N–O bond in complex 2. We anticipate that these two complexes would be potential high-energy density materials.

TGA, DSC and DFT Studies of TKX‐50, ABTOX and Their Key Precursors

“…Research and development work is being carried out all over the world in the area of energetic materials based on heterocyclic compounds . Nitrogen heterocycles are the fore‐front runners in the category of ionic liquid based energetic materials .…”

Microporous Materials in Scalable Shapes: Fiber Sorbents

“…Since an MOF has a metal source, it has a relatively wide range of structural densities of 300–2000 kg/m 3 compared to those of organic frameworks such as the covalent organic framework (COF) and zeolite templated carbon (ZTC) (Table ), − which have structural densities of about 200–700 kg/m 3 and about 500 kg/m 3 , respectively. − This physical property provides a huge advantage in the preparation of dope solutions because, as mentioned above, low-density sorbents require high volumetric loadings, which lead to high dope solution viscosity challenging to process. Also, an additional step of volumetric benefit can be achieved by using metal oxide precursors in a polymer dope followed by MOF conversion through postspinning treatment, for maximum sorbent load in fiber sorbents.…”

Energetic Salts of Sensitive N,N′-(3,5-Dinitropyrazine-2,6-diyl)dinitramide Stabilized through Three-Dimensional Intermolecular Interactions

“…Recently, various research groups disclosed the preparation of EMOFs based on nitro (NO 2 ) or nitramide (NHNO 2 )-substituted azole rings. , However, these EMOFs show a decrease in stability with the increase in explosophore units, and only a few show balance between performance and stability (Figure ). − Recently, several EMOFs were disclosed based on nitrogen-rich five-membered rings . In contrast, there are only a few reports of EMOFs based on planar six-membered azines …”

“…26−28 Recently, several EMOFs were disclosed based on nitrogen-rich five-membered rings. 29 In contrast, there are only a few reports of EMOFs based on planar six-membered azines. 30 Pyrazine-based energetic compounds are often under the spotlight by virtue of their good thermal stability, high density, planar geometry, and facile syntheses.…”