Exoergic pathways triggered by O/H radicals in different metallic carbohydrazide perchlorates (M2+ = Mn2+, Fe2+, Co2+, Ni2+, Zn2+ and Cd2+)

Metal-Determined Explosive Characteristics of M(NO3)2(1-AT)x of Thermal and Laser Ignition (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+; x = 2 or 3)

Optical and thermal ignition are two common pathways to initiate the explosion of primary explosives, where laser ignition is a more reliable and safer initiation method. Caused by the current-applied laser igniter with the wavelength of 1064 or 915 nm, the energetic complexes with strong absorption in the near-infrared (NIR) region are possibly applied as laser-ignited explosives. Recently, [Cu(NO3)2(1-AT)3] complex has been synthesized with excellent NIR absorption properties, where 1-amino-5H-tetrazole (1-AT) has been proved to be a promising laser-ignited energetic ligand. To confirm the structure-thermal/optical explosive characteristics, based on the structure of synthesized [Cu(NO3)2(1-AT)3], the commonly used transition-metal cations (M2+ = Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) have been selected to construct the series of complexes of M(NO3)2(1-AT)x (x = 2 or 3) theoretically. Car-Parrinello molecular dynamics (CPMD) method has been applied to unveil the role of center metals in the initiation and growth pathways. Time-dependent density functional theory (TD-DFT) method is used to explore their charge-transfer (CT) characteristics. The optical characteristic of the metal complex is mainly determined by the behaviors of the 3d electrons of center metals in excitation, where the activity of β-d electrons is an important factor to affect the NIR characteristic of complexes.

Compressive Symbol: A New Way to Evaluate the High-Pressure Behaviors of Energetic Tetrazole Materials

Energetic materials may transit to different phases or decompose directly under compression. Their reactivity in the explosions can be evaluated by their high-pressure induced behaviors, including polymorphism or phase transition. Here, we applied DFT methods to understand high-pressure behaviors of four typical tetrazole derivate crystals, including 5-aminotetrazole (ATZ), 1,5-aminotetrazole (DAT), 5-hydrazinotetrazole (HTZ), and 5-azidotetrazole (ADT), under the gradually increased pressure from ambient pressure to 200 GPa. In response to the extreme-high pressures, the performances are dominated by compressibility of crystals, reflected by compressive symbols on the basis of the molecular orientation in crystals. The crystal with weak compressibility (large symbol) generally dissociates, triggered by cleavage of weak bonds. However, the crystal with low compressive symbol is generally corresponding to a pressure-induced structural transformation or phase transition.