Noncovalent Modification of 4,4′-Azo-1,2,4-triazole Backbone via Cocrystallization with Polynitroazoles

Abstract

The investigation of high-nitrogen compounds has been significant for the evolution of energetic materials. Azo-bis-1,2,4-triazole (aTRz) can be an excellent energetic backbone, owing to its characteristics: high heat of formation, high nitrogen content, and plane structure. Nevertheless, aTRz-based energetic compounds have been rarely synthesized using the covalent modification method, owning to the decomposition of aTRz under harsh reaction conditions. Cocrystallization has been widely used as a mild and efficient method for modulating the properties of energetic compounds. In this study, electrostatic potential (ESP) maps were used for theoretical guidance, and four aTRz-based energetic cocrystals have been obtained via cocrystallization. The single-crystal structures of these cocrystals indicated that the N···H–N hydrogen bonds between the side nitrogen atoms of aTRz and the amino groups of the nitro azole compounds were the driving force for the assembly of multimers with aTRz and polynitroazole compounds. Consequently, the formation of cocrystals via the self-assembly of these multimers was driven by other weak hydrogen bonds and van der Waals forces. The detonation performance of aTRz-based cocrystals was increased by appropriately selecting the coformers. Particularly, when 4-amino-3,5-dinitro-pyrazole (ADNP) was used as coformer, resultant cocrystal 3 was a potential high-energy density material that exhibited high density, high detonation velocity (8329 m s–1) and detonation pressure (28.6 GPa). Thus, in this study, cocrystallization has been demonstrated to be an effective method for the noncovalent modification of aTRz-based energetic materials.

Eutectics and Salt of Dapsone With Hydroxybenzoic Acids: Binary Phase Diagrams, Characterization and Evaluation

“…40 The values of MEP are closely related to the strength of intermolecular interactions between 2 molecules and could be used as an indicator to evaluate the possibility of formation of multicomponent solids such as co-crystals and salts. 41 The MEP mapped on the vdW surface of DAP and coformer molecules where red color represents the positive potential and cyan represents the negative potential (Fig. 10).…”

Investigating the Stabilizing Forces of Pentazolate Salts

“…Layer-by-layer assembly of energetic molecules is an advantageous means of producing advanced materials. − Cocrystallization is an effective method for modifying the properties of the existing energetic compounds. , Given the structural features of 4 , we used the strong triazole-amino hydrogen bond to implement this critical intermolecular association in forming cocrystal 5 with TATOT. Compound 5 exhibits an unprecedented cyclo -N 5 – ···TATOT + ···TATOT triple stacking arrangement (Figure ), which we propose is a result of the competition between hydrogen bonding and π-stacking.…”

Review of the Intermolecular Interactions in Energetic Molecular Cocrystals

“…With respect to DNPP-based EMCCs (Figure l), the coformers 3-AT and 4-AT (Figure b2,b3) are both N rich, while they contain NH 2 as a HBD to form a rather strong HB . As a high-nitrogen azo-containing heterocyclic compound, aTRz (Figure k) includes several N atoms and a large conjugated structure and therefore can be a strong HBA as well . BTNMBT (Figure h) is perchlorate-free and exhibits a certain ability to form cocrystals with various coformers .…”

“…58 As a highnitrogen azo-containing heterocyclic compound, aTRz (Figure 1k) includes several N atoms and a large conjugated structure and therefore can be a strong HBA as well. 59 BTNMBT (Figure 1h) is perchlorate-free and exhibits a certain ability to form cocrystals with various coformers. 60 Similarly, the BTO molecule (Figure 1p) possesses two OH groups that facilitate the formation of intra-or intermolecular HBs.…”