Achieving the highest density and energy within diazo-oxide compounds

Diazo-oxide compounds are energetic materials with diverse structures and a wide range of applications. However, these compounds exhibit low density and energy (detonation velocity), with values lower than 1.810 g cm⁻³ and 8100 m s⁻¹, respectively. To increase the density and energy limits of diazo-oxide compounds, dinitromethyl and trinitromethyl groups were introduced to the 4-diazo-5-nitro-pyrazol-3-one zwitterion (DNPO) system to produce two new diazo-oxide compounds: 1-dinitromethyl-4-diazo-3-nitro-5-oxo-pyrazole zwitterion (compound 2) and 1-trinitromethyl-4-diazo-3-nitro-5-oxo-pyrazole zwitterion (compound 3). Experimental results and theoretical evaluation revealed that compound 3 exhibited a density of 1.917 g cm⁻³ and a detonation velocity of 9012 m s⁻¹, both ranked as the new peaks among all diazo-oxide compounds. Based on X-ray data and quantum computing, in addition to the weight effect of the dinitromethyl and trinitromethyl groups, the significant changes in noncovalent interactions and crystal packing generated by their introduction also contributed to the increase in density of these compounds. Despite the high energy, compound 3 was sensitive to outside stimuli (IS: 3J, FS: 50 N), making practical application relatively difficult.