Coordination Polymerization of Metal Azides and Powerful Nitrogen-Rich Ligand toward Primary Explosives with Excellent Energetic Performances

Advancement
in explosive systems toward miniaturization and enhanced
safety has prompted the development of primary explosives with powerful
detonation performance and relatively low sensitivities. Energetic
coordination polymers (ECPs) as a new type of energetic materials
have attracted wide attention. However, regulating the energetic characters
of ECPs and establishing the relationship between structure and energetic
property remains great challenges. In this study, two isomorphic 2D
π-stacked solvent-free coordination polymers, [M­(N3)2(atrz)]n (M = Co 1, Cd 2; atrz = 4,4′-azo-1,2,4-triazole), were
hydrothermally prepared and structurally characterized by X-ray diffraction.
The two compounds exhibit reliable stabilities, remarkable positive
enthalpies of formation, and prominent heats of detonation. The enthalpy
of formation of 1 is 4.21 kJ·g–1, which is higher than those of all hitherto known primary explosives.
Repulsive steric clashes between the sensitive azide ions in 1 and 2 influence the mechanical sensitivities
deduced from the calculated noncovalent interaction domains. The two
energetic π-stacked ECPs 1 and 2 can
serve as candidates for primary explosives with an approved level
of safety.