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Substitution of Nitrogen-Rich Linkers with Insensitive Linkers in Azide-Based Energetic Coordination Polymers toward Safe Energetic Materials
Primary explosives with powerful and reliable stabilities have attractive applications in the field of military and civilian technologies. In this work, four two-dimensional, solvent-free metal azide-based energetic coordination polymers [M(N3)2(btze)] n (M = Co for 1, Cd for 2; btze = 1,2-bis(tet...
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| Published in: | Crystal growth & design 2019-07, Vol.19 (7), p.3934-3944 |
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| Main Authors: | , , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Primary explosives with powerful and reliable stabilities have attractive applications in the field of military and civilian technologies. In this work, four two-dimensional, solvent-free metal azide-based energetic coordination polymers [M(N3)2(btze)] n (M = Co for 1, Cd for 2; btze = 1,2-bis(tetrazol-1-yl)ethane), [Cd2(N3)3Cl(btze)2] n 3, and [Cd2(N3)2Br2(btze)2] n 4 were prepared through a hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. All four compounds exhibit two times higher heats of detonation than that of the traditional lead azide (LA), high thermal stabilities (>200 °C), and relatively low sensitivities. The values of enthalpies of formation (Δf H°) of 1 and 2 are high up to 4.088 and 3.925 kJ·g–1, respectively, which belong to those of the largest Δf H° values among metal-based primary explosives. Although 1 and 2 are isostructural energetic compounds, their mechanical sensitivities are discrepant, which mainly originates from different metal atomic radii and distinct levels of repulsive steric clashes between the adjacent azides. As the less sensitive ligand btze is present in place of the previously reported atrz (4,4′-azo-1,2,4-triazole), the resultant coordination polymers with the same metal center exhibit lower mechanical sensitivities confirmed by experimental results and theoretical analyses. The mechanical sensitivities of 3 and 4 with almost the same structures display similarities despite different types and amounts of halogen ions in place of azide ions. Compounds 1 and 2 are detonated with a powerful blast. The sensitivities of 1 and 2 are in the range of applicable primary explosives, which makes 1 and 2 act as competitive and safe primary explosives. |
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| ISSN: | 1528-7483 1528-7505 |
| DOI: | 10.1021/acs.cgd.9b00351 |