Isomer-driven pyrazole frameworks: structural and zwitterionic insights for advanced energetics

Abstract

High-energy density materials (HEDMs) demand innovative molecular strategies for achieving optimized detonation performance, stability, and insensitivity. Now we present an isomer-driven design of two advanced energetic frameworks: a high-energy compound, 5-(3,4-dinitro-1H-pyrazol-5-yl)-3-(trinitromethyl)-1H-1,2,4-triazole (5) and zwitterionic compound 11, N-(5-(5-amino-1,3,4-oxadiazol-2-yl)-4-nitro-1H-pyrazol-3-yl)nitramide (11). The detonation performance was predicted using EXPLO5 (v7.01.01), while thermal stability and sensitivity were evaluated through DSC, and BAM impact and friction apparatus. Additionally, Multiwfn and VMD software were used to visualize ESP maps and LOL-π isosurfaces, providing insights into electronic structure and charge distribution. Compound 5 has an impressive density of 1.926 g cm⁻³, high detonation velocity of 9206 m s⁻¹, outperforming RDX with an acceptable thermal stability of 163.9 °C. Compound 11 has an excellent density of 1.918 g cm⁻³, an RDX-like detonation velocity of 8797 m s⁻¹, exceptionally high thermal stability of 242.7 °C, and is insensitive to external stimuli. The outstanding properties of 11 are attributed to its zwitterionic nature, as confirmed by crystal structure analysis, NCI interactions, ESP and aromaticity studies. These findings highlight a paradigm for leveraging positional isomerism and zwitterionic architectures to advance the design of HEDMs with superior performance and stability.