Balancing energy and safety in a nitropyrazole-based melt-cast explosive carrier: 1,4-dimethyl-3,5-dinitropyrazole

Abstract

The development of melt-cast explosives with balanced energy, safety, and processability remains a critical challenge due to the inherent trade-offs among these properties. Herein, we report a rationally designed melt-cast explosive carrier, 1,4-dimethyl-3,5-dinitropyrazole (DMDNP), synthesized via a one-step nitration from commercially available precursors. DMDNP exhibits a favorable melting point (101.0 °C), high thermal stability (T_d = 300.6 °C), and a density of 1.638 g cm⁻³ at 118 K. The detonation performance, based on EXPLO5 calculations, reaches a velocity of 7082 m s⁻¹ and a pressure of 19.2 GPa, outperforming traditional TNT and significantly exceeding DNAN. Notably, DMDNP demonstrates low mechanical sensitivities (IS = 50 J, FS > 360 N, and E₅₀ = 9.3 J), attributed to a synergistic combination of high bond dissociation energy, herringbone crystal packing, and a low proportion of unfavorable O⋯O and O⋯N intermolecular contacts. With straightforward synthesis, favorable thermal behavior, enhanced detonation performance, and low sensitivity, DMDNP exhibits well-balanced properties and holds promise for further application studies as a next generation melt-cast explosive carrier.