Single-crystal-to-single-crystal MOF encapsulation of copper azide to prepare laser-sensitive primary explosives

Abstract

Laser-sensitive primary explosives (LSPEs) are crucial material bases of advanced laser initiation technology. Copper azide (CA), a primary explosive with excellent detonation properties, is limited in preparation and application owing to its extremely high sensitivity. Thus, incorporating CA into LSPEs relies on precise desensitisation strategies. This study successfully implemented a strategy involving sensitive-unit molecular-scale encapsulation. A 2D energetic metal–organic framework (EMOF) [Cu(ATRZ)(N₃)₂]_n (CA-ATRZ) (ATRZ = 4,4′-azo-1,2,4-triazole) was designed and synthesized via a safe and facile single-crystal-to-single-crystal (SCSC) transformation from a 3D EMOF [Cu(ATRZ)₃(NO₃)₂]_n. Leveraging its distinctive structural attributes of encapsulated confinement, CA-ATRZ is substantially improved in terms of safety compared to CA, while maintaining its superior detonation performance. Furthermore, CA-ATRZ obtained by combining MOFs with CA has outstanding ultrafast direct laser initiation characteristics, is free of toxic metals and perchlorate, has high initiating ability, and has decent thermal stability. This strategy could pave the way for developing advanced high-energy LSPEs.