Tonglai Zhang

Synthesis, structural investigation, thermal decomposition mechanism and sensitivity properties of an energetic compound [Cd(DAT)6](ClO4)2 (DAT=1,5-diaminotetrazole)

An energetic coordination compound [Cd(DAT)(6)](ClO(4))(2) has been synthesized by using 1,5-diaminotetrazole (DAT) as ligand and its structure has been characterized by applying X-ray single crystal diffraction, elemental analysis and FT-IR spectroscopy. The central cadmium(II) cation is coordinated by six N atoms from six DAT molecules to form a six-coordinated and distorted octahedral structure. Di-dimension layer structure was formed and the layers were linked together by the extensive intermolecular hydrogen bonds between DAT ligands and ClO(4)(-) anions. Thermal decomposition mechanism of the title compound was predicted based on DSC, TG-DTG and FT-IR analyses results. The kinetic parameters of the first exothermic process of the title compound were studied by applying the Kissingers and Ozawa-Doyles methods. Sensitivity tests reveal that the title compound has sensitive nature.

Synthesis, crystal structure, thermal decomposition, and non-isothermal reaction kinetic analysis of an energetic complex: [Mg(CHZ)3](ClO4)2 (CHZ = carbohydrazide)

An energetic complex [Mg(CHZ)3](ClO4)2 was synthesized by the reaction of carbohydrazide (CHZ) with magnesium perchlorate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The crystal belongs to the monoclinic system with space group P2(1)/n. Cell parameters: a = 10.034(2) Å, b = 8.5069(16) Å, c = 21.285(4) Å, β = 100.901(3)°, V = 1784.1(6) Å3, Z = 4. The central magnesium is six-coordinate with three oxygen atoms of carbonyl groups and three terminal nitrogen atoms of the hydrazine groups from three CHZs to form a distorted octahedron. Differential scanning calorimetry and thermogravimetric-differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics. The equation can be expressed as . Moreover, the values of critical temperature of thermal explosion, ΔS≠ , ΔH≠ , ΔG≠ , and the energy of combustion were obtained as 284°C, −169.76 J mol−1 K−1, 65.46 kJ mol−1, 154.27 kJ mol−1, and 6759 kJkg−1, respectively.

A novel cocrystal explosive NTO/TZTN with good comprehensive properties

In order to decrease the acidity of the highly explosive 3-nitro-1,2,4-triazol-5-one (NTO), we cocrystallized NTO with a nitrogen-rich weak base compound 5,6,7,8-tetrahydrotetrazolo[1,5-b] [1,2,4]-triazine (TZTN) in a molar ratio 1 : 1 to form a novel cocrystal explosive. Structure determination showed that the cocrystal is formed by strong intermolecular hydrogen bond interaction. Optical microscopy demonstrated that the crystal morphology of the cocrystal was significantly improved in contrast to the crystal of NTO and TZTN. The differential scanning calorimetry (DSC) showed that the cocrystal exhibited the enhancement of thermal stability and became less sensitive to impact, compared with the TZTN. Moreover, the results suggested that the NTO/TZTN cocrystal not only has unique performance itself, but also effectively alters the properties of NTO and TZTN.

Nitrogen-rich salts based on the energetic [monoaquabis(N,N-bis(1H-tetrazol-5-yl)amine)-zinc(II)] anion: a promising design in the development of new energetic materials.

Nitrogen-rich energetic salts involving various cations (lithium, 1; ammonium, 2; hydrazinium, 3; hydroxylammonium, 4; guanidinium, 5; aminoguanidinium, 6; diaminoguanidinium, 7; and triaminoguanidinium, 8) based on nitrogen-rich anion [Zn(BTA)2(H2O)](2-) (N% = 65.37, BTA = N,N-bis[1H-tetrazol-5-yl]amine anion) were synthesized with a simple method. The crystal structures of all compounds except 1, 2, and 6 were determined by single-crystal X-ray diffraction and fully characterized by elemental analysis and FT-IR spectroscopy. The thermal stabilities were investigated by differential scanning calorimetry (DSC). The DSC results show that all compounds exhibit high thermal stabilities (decomposition temperature >200 °C). Additionally, the heats of formation were calculated on the basis of the experimental constant-volume energies of combustion measured by using bomb calorimetry. Lastly, the sensitivities toward impact and friction were assessed according to Bundesamt für Materialforschung (BAM) standard methods.

Synthesis, structure, and thermal behavior of a 2-D polymeric Ca(II) compound with tetrazole-1-acetic acid

A 2-D polymeric Ca(II) compound, [Ca(tza)2(H2O)2] n , was synthesized by the reaction of tetrazole-1-acetic acid with calcium carbonate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The calcium center is six-coordinate in a slightly distorted octahedral configuration by four carboxylic oxygens from four different tza− ligands and two waters. The 2-D supramolecular laminar structure in b-axis × c-axis plane was constructed via four bridging tza− ions connecting one Ca(II) with four adjacent Ca(II) ions. Differential scanning calorimetry and thermogravimetric–differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 21.96–262.2 × 103/RT. The values of critical temperature of thermal explosion, ΔS≠ , ΔH≠ , and ΔG≠ were obtained as 574 K, −67.62 J mol−1 K−1, 257.52 kJ mol−1, and 295.59 kJ mol−1, respectively.

A screened hybrid density functional study on energetic complexes: cobalt, nickel and copper carbohydrazide perchlorates.

The molecular geometry, electronic structure, infrared spectra and thermochemical properties of cobalt and nickel tris(carbohydrazide) perchlorates (CoCP and NiCP) as well as copper bis(carbohydrazide) perchlorate (CuCP) were investigated using the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid density functional. The results show that both perchlorate ions coordinate with the copper atom, and the interactions between copper and perchlorate are ionic, whereas all the metal-carbohydrazide interactions are covalent. Due to the delocalization from the sigma(N-H) bond orbital to the n*(M) antibond orbital, the amino stretching vibrations of these complexes show considerable red-shift compared with those of free carbohydrazide ligand. The calculated heats of reaction and formation indicate that the formations of these complexes are exothermic, and the order of their thermal stability is NiCP>CoCP>CuCP. These agree well with the experimental results. Finally, we find that there is a relationship between the energy gap and impact sensitivity.

Research on thermal decomposition of trinitrophloroglucinol salts by DSC, TG and DVST

AbstractThe thermal decomposition of the four nitrogen-rich salts of ammonia (NH4), aminoguanidine (AG), carbohydrazide (CHZ) and 5-aminotetrazo (ATZ) based on trinitrophloroglucinol (H3TNPG) was investigated using the differential scanning calorimetry (DSC), thermogravity (TG), and dynamic vacuum stability test (DVST). DSC and TG methods research the complete decomposition, while DVST method researches the very early reaction stage. The peak temperatures of DSC curves are consistent with the temperatures of maximum mass loss rates of TG curves. The apparent activation energies of these H3TNPG-based salts obtained by DSC and DVST have the same regularity, i.e., (ATZ)(H2TNPG)·2H2O < (CHZ)(HTNPG)·0.5H2O < NH4(H2TNPG) < (AG)(H2TNPG). The thermal stability order is (ATZ)(H2TNPG)·2H2O < (CHZ)(HTNPG)·0.5H2O < (AG)(H2TNPG) < NH4(H2TNPG), which was evaluated by DVST according to the evolved gas amount of thermal decomposition. DVST can monitor the real-time temperature and pressure changes caused by thermal decomposition, dehydration, phase transition and secondary reaction, and also evaluate the thermal stability and kinetics.

Crystal structures, thermal decompositions and sensitivity properties of [Cu(ethylenediamine)2(nitroformate)2] and [Cd(ethylenediamine)3](nitroformate)2.

Two new coordination compounds [Cu(ethylenediamine)(2)(nitroformate)(2)] and [Cd(ethylenediamine)(3)](nitroformate)(2) were synthesized and characterized through elemental analysis, IR and UV spectra. Their crystal structures were determined through X-ray single crystal diffraction. The first compound crystallizes in the triclinic space group P1; the second one crystallizes in the orthorhombic space group Pbca. For the first compound, central Cu(II) ion is hexa-coordinated with two ethylenediamine ligand molecules and two nitroformate anions to form the centrosymmetric octahedral structure. For the second one, central Cd(II) ion is hexa-coordinated with three ethylenediamine ligand molecules to form the slightly distorted octahedra. Through hydrogen bonds, molecules are linked together to form the three-dimensional packing diagrams. Thermal decomposition mechanisms of these two compounds were predicted through DSC, TG-DTG and FTIR analyses. In addition, the impact sensitivity, friction sensitivity and flame sensitivity were measured. All observed properties show that the first one has high energy, good thermal stability and moderate flame sensitivity.

Preparation, crystal structures, thermal decompositions and explosive properties of two new high-nitrogen azide ethylenediamine energetic compounds

Two new multi-ligand coordination compounds of copper(II) ethylenediamine (en) azide and cobalt(III) ethylenediamine azide, [Cu2(en)2(N3)4]n (1) and Co(en)2(N3)2(NO3) (2), were synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structures were determined by X-ray single crystal diffraction. The obtained results show that the crystals of 1 and 2 belong to the monoclinic, C2/c space group. The metal cations are six-coordinated with the azido ligands and ethylenediamine molecules through nitrogen atoms. The coordination modes of the azido-groups were μ-1, μ-1,1 and μ-1,1,3 modes for 1, and μ-1 mode for 2. Under a nitrogen atmosphere, with a heating rate of 5 K min−1, the thermal decompositions contain two main exothermic stages in the DSC curves corresponding to the TG-DTG curves. The non-isothermal kinetics parameters were calculated by the Kissingers method and Ozawas method, respectively. The energies of combustion, enthalpies of formation, critical temperature of thermal explosion, entropies of activation (ΔS≠), enthalpies of activation (ΔH≠), and free energies of activation (ΔG≠) were measured and calculated. The sensitivity properties were also determined with standard methods and the results showed that 1 had a much higher flame sensitivity and lower impact sensitivity.

Energetic Salts Based on Tetrazole N-Oxide

Energetic materials (explosives, propellants, and pyrotechnics) are used extensively for both civilian and military applications and the development of such materials, particularly in the case of energetic salts, is subject to continuous research efforts all over the world. This Review concerns recent advances in the syntheses, properties, and potential applications of ionic salts based on tetrazole N-oxide. Most of these salts exhibit excellent characteristics and can be classified as a new family of highly energetic materials with increased density and performance, alongside decreased mechanical sensitivity. Additionally, novel tetrazole N-oxide salts are proposed based on a diverse array of functional groups and ions pairs, which may be promising candidates for new energetic materials.