Two bimetallic complexes of 4-hydroxy-3,5-dinitropyrazole, [K2Mn(DNPO)2(H2O)4]n2∙H2O (BMEP-1) and [K2Zn(DNPO)2(H2O)6]n (BMEP-2) were synthesized and characterized by IR spectroscopy and elemental analysis. The crystal structures of BMEP-1 and BMEP-2 were determined by...
The cocrystallization effect plays a prominent role in
improving
the performance of energetic materials. A combinational strategy based
on density functional tight-binding molecular dynamics (DFTB-MD) simulations
and density functional theory (DFT) was used to elucidate the decomposition
mechanisms and reaction kinetics of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine
(HMX)-based cocrystal explosives [HMX/N,N-dimethylformamide (DMF) and HMX/bis(2,4-dinitro-2,4-diazapentane)
(DNDAP)] at high temperatures. The decomposition and reaction mechanisms
of the two cocrystals showed great dependence on the temperature.
In the HMX/DMF cocrystal, a conformational change of HMX at 2000 K
and subsequent initial decomposition of HMX at 2500 K is involved.
At 3000 K, the global decomposition and interaction of the HMX and
cocrystal molecules occurred. There are two dominant competing reaction
channels in the two cocrystals. The comparative results reveal that
the HMX molecules have a larger reactivity with DNDAP at low temperatures
but with DMF at high temperatures. The decomposition pathways of the
HMX molecules based on DFT calculations were studied as a useful addition
to the MD results. These findings provide a basic understanding of
the thermal decomposition mechanisms and reaction kinetics of HMX-based
cocrystal energetic materials at high temperatures.
A flexible and multifunctional 4-hydroxy-3,5-dinitropyrazole (DNPO) ligand was produced while seeking "green" energetic coordination polymers (ECPs). A series of alkali metal and alkaline earth metal ECPs of DNPO were successfully prepared and comprehensively characterized using elemental analysis, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. All ECPs were characterized via single-crystal X-ray diffraction. They have high crystal densities ranging from 1.743 (ECP-6) to 3.399 g cm −3 (ECP-5). Furthermore, various shapes of zero-dimensional (0D), onedimensional (1D), two-dimensional (2D), and three-dimensional (3D) supramolecular structures were found for the preparation of ECP, and each metal was combined in a specific and characteristic manner. All the prepared ECPs show excellent thermal stability, and the decomposition temperatures are higher than 347.0 °C (ECP-9) and 418.0 °C (ECP-1), due to the numerous coordination bonds and the network structure of the complex. The sensitivities toward impact and friction were tested using standard methods, and most of ECPs (ECP-1, ECP-2, and ECP-6 to ECP-9) can be considered insensitive to impact and friction, with values higher than 40 J and 360 N, respectively. ECP-3, ECP-4, and ECP-5 are sensitive toward impact (30, 12, and 8 J, respectively), while they are insensitive toward friction (≥360 N). Upon their combustion, these ECPs exhibit a series of unique flame colors, making them promising flame colorants for various ecofriendly pyrotechnic formulations.
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