Construction of high energy density azasydnone-pyrazole compounds

The search for advanced energetic materials has shifted beyond traditional groups like nitro to explore non-conventional explosophores. Among these, the azasydnone ring stands out, combining a zero-oxygen balance with high-energy bonds (N-N, N-O, N=N) for stable energy storage. Here, we report the introduction of azasydnone rings at different positions of dinitropyrazole. Although they have the same substituent group, the change of the position of the azasydone ring makes the two compounds show great differences in crystal density (4-azasydnone-3,5-dinitropyrazole 1.830 g·cm −3 , 5-azasydnone-3,4-dinitropyrazole 1.981 g·cm −3 ). Molecular structures are confirmed by 1 H and 13 C NMR, IR spectroscopy, and X-ray crystal diffraction. This serves as an example of the ability to construction of high-density azasydnone compounds. • Achieving the targeted introduction of azasydnone rings at two substitution sites on dinitropyrazole. • 5-azasydnone-3,4-dinitropyrazole (5) demonstrates high density (1.981 g cm −3 at 170 K) and excellent detonation performance ( D v : 9293 m s −1 , p : 38.8 GPa), making it the most outstanding azasydnone-based compound reported to date. • This method pave a new way for guiding the synthesis of high-density azasydnone-based energetic materials