Mixed-Metallic Energetic Metal–Organic Framework: New Structure Motif for Potential Heat-Resistant Energetic Materials

Abstract

The incessant pursuit of heat-resistant explosives with balanced energetic performance and safety is indispensable in civil and military sectors, particularly when employed in harsh environments. Herein, a new nanostructured highly energetic metal−organic framework (E-MOF), based on nickel(II) and sodium(I) mixed-metal has been constructed using an energetic poly tetrazole molecule by the hydrothermal approach. The Na/ Ni-MOF was thoroughly characterized using infrared radiation (IR), thermogravimetric analysis and differential scanning calorimetry, scanning electron microscopy, and powder X-ray diffraction analyses. Further, the crystal structure was authenticated by single crystal X-ray diffraction analysis, and their crystal packing features were well explored, revealing a wave-like 3D framework having a crystal density of 1.985 g cm −3 . This mixed-metallic E-MOF demonstrated a good enthalpy of combustion (−7.91 kJ•g −1 ), a good velocity of detonation (VOD = 7410 m s −1 ) exceeding that of trinitrotoluene (TNT, 6820 m/s) and Hexanitrostilbene (HNS, 7164 m/s), and excellent insensitivity [impact sensitivity (IS) > 40 J and friction sensitivity (FS) > 360 N]. Additionally, it exhibits outstanding thermal stability (T d = 387 °C). These fine-tuned properties are superior to those of continuously used benchmark heat-resistant explosives HNS and 2,4,6-triamino-1,3,5trinitrobenzene, suggesting that the newly reported poly tetrazole-based E-MOF is beneficial for improved physical performance. The results given in the present work highlighted the advantages of the mixed-metallic E-MOF as a potential heat-resistant explosive for future applications.

Highly Dense N–N-Bridged Dinitramino Bistriazole-Based 3D Metal–Organic Frameworks with Balanced Outstanding Energetic Performance

“…According to the Hirshfeld surface, the shape represents the planar conjugated structure, which contributes to insensitivity toward mechanical stimuli. Also, red dots reveal the primary interactions, which should be situated at the edge surface for more stacked interactions to adhere to the external stimuli . Thus, the Hirshfeld surfaces of K-MOF and Na-MOF agree with the above criteria and authenticate the experimental stability and sensitivity results.…”

“…Thus, the impact sensitivity (IS) and friction sensitivity (FS) of both compounds were explored with a BAM fall hammer and a BAM friction tester. As shown in Table , both E-MOFs demonstrate high insensitivity toward mechanical stimuli (FS > 360 N, IS = 30 J for K-MOF; FS > 360 N, IS = 40 J for Na-MOF), which is similar to or higher than benchmark explosives RDX (FS = 120 N, IS = 7.5 J), HNS (FS = 240 N, IS = 5 J), CL-20 (FS= 48 N, IS= 4 J), and HMX (FS = 120 N, IS = 7.5 J). ,, In addition, both E-MOFs reveal superior insensitivity in comparison to previously reported K-MOFs such as K 2 DNAF (FS = 120 N, IS = 1 J), K 2 DNABT (FS < 1 N, IS = 1 J), and K 2 DNAT (FS < 5 N, IS = 1 J), which may be attributed to the strong structural reinforcement and high dimensionality of both E-MOFs.…”