N-Functionalization of 5-Aminotetrazoles: Balancing Energetic Performance and Molecular Stability by Introducing ADNP

Abstract

5-aminotetrazole is one of the most marked high-nitrogen tetrazole compounds. However, the structural modification of 5-aminotetrazole with nitro groups often leads to dramatically decreased molecular stability, while the N-bridging functionalization does not efficiently improve the density and performance. In this paper, we report on a straightforward approach for improving the density of 5-aminotetrazole by introducing 4-amino-3,5-dinitropyrazole. The following experimental and calculated properties show that nitropyrazole functionalization competes well with energetic performance and mechanic sensitivity. All compounds were thoroughly characterized using IR and NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Two energetic compounds (DMPT-1 and DMPT-2) were further confirmed by implementing single-crystal X-ray diffraction studies. Compound DMPT-1 featured a high crystal density of 1.806 g cm−3, excellent detonation velocity (vD = 8610 m s−1), detonation pressure (P = 30.2 GPa), and impact sensitivity of 30 J.

Asymmetrical Methylene-Bridge Linked Fully Iodinated Azoles as Energetic Biocidal Materials with Improved Thermal Stability

“…A symmetric or asymmetric structure is always formed alternatively when a connecting bridge is introduced. Compared with a symmetric structure that is limited by the constraints of a single-ring molecular skeleton, an asymmetric structure can build more molecular skeletons by freely combining different skeletons, resulting in more diversified molecular structures to achieve optimal comprehensive performance [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. The asymmetric bridge compounds based on oxadiazole rings through theoretical calculations and analyses demonstrate that the formation enthalpy, density, and detonation performance of the asymmetric compound are significantly improved [ 37 ].…”

“…Although 4-amino-3,5-dinitropyrazole (LLM-116) is a representative compound with a high density and low-impact sensitivity, its low decomposition temperature hinders its practical application. By methylene bridging with different ring skeletons (1,2,3-triazole or tetrazole), along with adjustable regional isomerization, it achieves higher thermal stability (T d : LLM-116: 178 °C, MPT-1: 190 °C, MPT-2: 269 °C, DMPT-1: 191 °C, DMPT-2: 209 °C) ( Figure 1 a) [ 40 , 41 ]. Based on N, N′ ethylene-bridging, energetic polyiodoazole compounds IETA and PETA were synthesized ( Figure 1 b) [ 42 ]; their iodine content decreased to a certain extent (iodine content: IETA = 68.3%, PETA = 68.3%), and due to the introduction of high-energy tetrazole, the thermal decomposition temperature of the compound decreased compared to the fully iodinated single-ring compound (T d : IETA: 186.2 °C, PETA: 247.3 °C).…”