Desensitization Induced by Alternating Layered Stacking: Structure–Property Correlation in CL-20/DMDNP Cocrystals

The pursuit of high-energy-density materials (HEDMs) with low mechanical sensitivity remains a paramount challenge in energetic materials science. This study addresses this challenge through the rational design and synthesis of a novel cocrystal formed between the powerful explosive CL-20 and the insensitive molecule 1,4-dimethyl-3,5-dinitropyrazole (DMDNP) in a 1:2 stoichiometry. Single-crystal X-ray diffraction reveals a unique alternating layered architecture (DMDNP|CL-20|DMDNP), where DMDNP layers act as spacers to isolate high-energy CL-20 layers. This cocrystal exhibits a significant reduction in mechanical sensitivity (impact sensitivity: 20 J) compared to pure CL-20, while maintaining competitive detonation performance (detonation velocity: 8227 m s^–1). Multiscale analysis reveals that its superior desensitization stems from a synergistic mechanism: at the molecular scale, the coformer DMDNP itself is insensitive; at the crystalline scale, the unique alternating layered stacking structure spatially isolates the high-energy CL-20 layers; at the interaction scale, the interlayer hydrogen-bonding network facilitates energy dissipation; and at the electronic structure scale, the reduced proportion of sensitive O···O/N short contacts combined with the optimized intralayer interaction network within CL-20 collectively lowers the propensity for hot-spot initiation. This work provides fundamental insights into how cocrystal engineering can balance energy and safety through tailored molecular packing, offering a promising strategy for the development of next-generation insensitive HEDMs.