Unsymmetrical Functionalization of Bis-1,2,4-triazoles Skeleton: Exploring for Promising Energetic Materials

Abstract

Unsymmetrical functionalization of bis-1,2,4-triazoles was attempted, and a series of nitrogen/oxygen-rich energetic materials were designed and synthesized in this study. Compared with previously reported symmetrical bis-1,2,4-triazole derivatives (iv and v), both unsymmetrically functionalized bis-1,2,4-triazole derivatives (3 and 7) in this work possess improved safety properties (impact sensitivities: 22 J (3) and 11 J (7); friction sensitivities: >360 N (3) and 250 N (7)). Meanwhile, the detonation performance of 3 was apparently improved compared with the C-nitrated compound iv. These features indicate that unsymmetrical functionalization would be a favorable strategy to construct energetic materials with both high energy and safety. Moreover, N-trinitromethyl-functionalized compound 5 possesses high density (1.92 g cm–3), positive oxygen balance (+25.1%), and desirable detonation performance similar to HMX, with higher specific impulse (I sp = 265.1 s) than ADN, suggesting its superiority as a highly energetic oxidizer.

Synthetic Strategies Toward Nitrogen-Rich Energetic Compounds Via the Reaction Characteristics of Cyanofurazan/Furoxan

“…During the past decades, heterocyclic five-membered rings of furazan, furoxan, isofurazan (1,2,4-oxadiazole and 1,3,4-oxadiazole), tetrazole, isoxazole, and their fused derivatives (such as pyridofurazan, triazolofurazan, pyridazinofuroxan etc.) are the most popular choice in the creation of new nitrogen-rich energetic compounds ( Tang et al, 2016a ; Zhang et al, 2017 ; Huang et al, 2020 ; Voronin et al, 2020 ; Yan et al, 2020 ; Dalinger et al, 2021 ; Larin et al, 2021 ). From the structural point of view, the frameworks based on the combinations of these heterocyclic five-membered rings, especially the ones with furazan, furoxan, tetrazole, or isofurazan units, can achieve more compact structures and higher enthalpy of positive formations, leading to corresponding nitrogen-rich energetic compounds with excellent detonation performances ( Jaidann et al, 2010 ; Swain et al, 2010 ; Suntsova and Dorofeeva, 2017 ).…”

Series of AzTO-Based Energetic Materials: Effect of Different π–π Stacking Modes on Their Thermal Stability and Sensitivity

“…Compared with traditional high-energy materials, the design of novel high-energy explosives is based on insights into multiple subjects, including synthetic methodology, crystal engineering, and computational science. − Crystal design of high-energy materials is also an important method. In nature, molecules with a layer-by-layer structure are widespread. − More importantly, highly ordered structures formed in this way often exhibit fascinating properties, which have enlightened researchers to advance in-depth research on this system. − …”

Computational investigation and screening of high‐energy‐density materials: Based on nitrogen‐rich 1,2,4,5‐tetrazine energetic derivatives

“…Meanwhile, its characteristics of high nitrogen and low hydrocarbon content make it have the dual effect of not only increasing the material density, but also achieving better oxygen balance easily. [ 3,4 ] Among them, the nitrogen content of tetrazine compounds reached 68.3% is a very effective structural unit in the design of high‐energy insensitive energy‐containing materials, tetrazine compounds have high thermal stability, high positive heats of formation (HOF) and low sensitivity, because of their powerful N–N and C–N bonds. [ 5‐8 ] With the increase of oxygen atoms coordinated with tetrazine, the density and properties of the molecule are improved, and the whole molecule tends to be stable.…”