Alkali Metals‐Based Energetic Coordination Polymers as Promising Primary Explosives: Crystal Structures, Energetic Properties, and Environmental Impact

Abstract

Coordination polymers (CPs) consisting of alkali metals (Na, K, Rb, and Cs) and a powerful nitrogen- and oxygen-rich energetic ligand (4,4'-bis(dinitromethyl)-3,3'-bisnitramide-methylene-furazanate, DBMF ) were developed. Molecular structures of these CPs, confirmed by single-crystal X-ray diffraction analysis, indicated that the same ligand takes on a U-shaped state for Na and an N-shaped state for K, Rb, and Cs. Explosion tests demonstrated that both Na DBMF and K DBMF efficiently detonated the secondary explosive RDX. This indicates that they are both effective primary explosives. K DBMF exhibits better calculated detonation performance (D: 8227 m s ; P: 32.5 GPa) than the primary explosive Pb(N ) . In addition, toxicity tests and evaluation of their decomposition products reveal their low impact on the environment. Both experimental results and theoretical analyses indicate that the combination of alkali metals and a powerful energetic ligand can stimulate the development of primary explosives.

Synthesis and characterization of the mixed-ligand coordination polymer Cu3Cl(N4C-NO2)2

“…Lead-free energetic compounds with high thermal and hydrolytic stability are highly sought-after materials in current efforts to replace lead-containing initiatory explosives such as lead azide and lead styphnate. [1][2][3][4][5] Although well-characterised and effective in their intended use, the latter compounds should be replaced due to the deleterious effects of their heavy metal content, which is present in all stages of their manufacture, storage, processing, use, remediation, and disposal. A number of alternatives with fewer health and environmental issues have been investigated and include, amongst others, 5-nitro-(1H)-tetrazolates of silver 6,7,14,18 and, in particular, copper azides and nitrotetrazolates (DBX-1).…”

“…A number of alternatives with fewer health and environmental issues have been investigated and include, amongst others, 5-nitro-(1H)-tetrazolates of silver 6,7,14,18 and, in particular, copper azides and nitrotetrazolates (DBX-1). [8][9][10][11][12] DBX-1 is a member of a family of energetic copper nitrotetrazolates consisting of Cu(en) 2 (NT) 2 , 14 Cu(NH 3 ) 3 (NT) 2 , 14 (M′) 2 [Cu 2+ (NT) 4 •(H 2 O) 2 ], 15 copper(I) nitrotetrazolate 16,17 or DBX-1, 8,9 Cu(NT) 2 18 and Cu(H 3 O)(NT) 3 •3H 2 O 10,13,19 (en = ethyl-ene diamine, NT = 5-nitrotetrazolate). The synthesis of DBX-1 is not straightforward.…”

“…Fronabarger and colleagues found that the nitric acid needed for the synthesis of NaNT can be replaced by the more cost effective sulphuric acid. 22 It was noted that the mechanism of the DBX-1 formation is composed of several steps and begins with an induction period in which Cu(H 3 O)(NT) 3 •3H 2 O (vide supra) acts as an intermediate. Ford and co-workers suggested that crystal seeds play a role.…”

“…10 Finally, Fronabarger provided a detailed preparative method for the synthesis of DBX-1 and reported yields ranging from 80% to 85%. 8,9,24,25 Neither polymorphs of DBX-1, nor any by-products other than the aforementioned Cu(H 3 O)(NT) 3 •3H 2 O, are known. In this paper, we detail results of an in-depth investigation into the selectivity of the reduction reaction discussed above, which forms not just DBX-1, but also a previously unreported compound depending on reaction conditions.…”

Higher performing and less sensitive CN7−-based high-energy-density material

“…Solvent molecules can sometimes generate interesting property changes in energetic materials. Crystal water plays an important role to establish hydrogen bonds, thus helping stabilize the molecule [27][28][29]. However, water molecules decrease the density and heat of formation, which results in lower detonation performance.…”