Jian-Guo Zhang

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 1u2006:u20061 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.

3,4-Diamino-1,2,4-triazole based energetic salts: synthesis, characterization, and energetic properties

The protonation or metathesis synthesis and energetic properties of a new class of energetic materials, energetic salts of 3,4-diamino-triazole (DATr), are described. They were characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), differential scanning calorimetry (DSC), and X-ray single-crystal diffraction. The DSC results showed that these salts had acceptable thermal stabilities; the decomposition temperatures of these salts, except compound 4, were over 200 °C. The density of the series of salts ranged from 1.704 g cm−3 (2 and 6) to 1.82 g cm−3 (7), placing them in a class of relatively dense compounds, and the heats of formation were calculated with the Gaussian 03 suite of programs. All the salts except 5 exhibited promising detonation performances (detonation pressure: 21.5–32.8 GPa, detonation velocity: 7017–8620 m s−1), which were much higher than both those of TNT, and salt 4 was even comparable to RDX. Impact sensitivities were also determined by hammer tests and the results ranged from 8 J (sensitive) to >40 J (insensitive).

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.

Energetic salts based on 3-hydrazino-4-amino-1,2,4-triazole (HATr): synthesis and properties

Several novel nitrogen-rich salts of 3-hydrazino-4-amino-1,2,4-triazole (HATr) were synthesized by means of metathesis reactions or Bronsted acid–base reactions in this work. These nitrogen-rich salts were fully characterized by means of single-crystal X-ray diffraction, elemental analysis, and infrared. Their structures showed that the extensive hydrogen bonding interactions between the cations and anions formed a complex 3D network, which contributes to the high density of the salts. Some of these salts exhibited reasonable thermal stability (Td = 168–266 °C) and good impact sensitivities (IS = 4–40 J). In addition, the detonation pressures and velocities of the energetic salts were calculated, ranging from 23.1 GPa to 32.3 GPa and 7421 m s−1 to 8455 m s−1, respectively.

A novel insensitive cocrystal explosive BTO/ATZ: preparation and performance

In order to explore new applications of novel nitrogen-rich energetic materials based on 1H,1′H-5,5′-bitetrazole-1,1′-diolate (BTO), aside from BTO based energetic-salts, a cocrystalline energetic material composed of BTO and 1-amino-1,2,3-triazole (ATZ) in a 1u2006:u20062 molar ratio was synthesized, which is the first reported BTO based material with a cocrystal structure. The structure of the cocrystal was characterized using powder X-ray diffraction and single crystal X-ray diffraction, which indicate that the cocrystal is formed by intermolecular hydrogen bonding interactions, and is crystallized in the monoclinic system, space group C2/c, with a density of 1.697 g cm−3. The properties of the cocrystal including the thermal decomposition, sensitivity, and detonation performances are discussed in detail. Differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG) technologies were employed to determine the thermal decomposition behavior of the cocrystal, and the results are significantly different from the decomposition behavior of the co-formers. The enthalpy of formation was calculated as 1376.5 kJ mol−1, which is obviously higher than that of RDX. Sensitivity studies showed that the cocrystal has an impact sensitivity of 24 J, and so is insensitive to impact stimulation. In addition, the detonation pressure (P) and detonation velocities (D) of the cocrystal were predicted by using K–J equations, and the results obtained are 8088 m s−1 for detonation velocity and 28.1 GPa for detonation pressure, which are at the same level as RDX. Combining these advantages, this cocrystal possesses a promising future for use as a type of insensitive explosive. The discovery of the cocrystal contributes significantly to the expansion and application of the chemistry of 1H,1′H-5,5′-bitetrazole-1,1′-diolate.

Hydrazine 5,5′-bitetrazole-1,1′-diolate: a promising high density energetic salt with good properties

The development of new environmentally friendly energetic compounds with reasonable detonation performance and safety is a long-term target in energetic materials research. A new energetic eco-friendly salt of hydrazine 5,5-bitetrazole-1,1-diolate (HA·BTO) is developed based on the reaction of 1H,1H-5,5-bitetrazole-1,1-diolate (BTO) with hydrazine hydrochloride (HA·HCl), and fully characterized. The monocrystal of the title salt is obtained and the structure is determined by powder X-ray diffraction and single crystal X-ray diffraction. Results show that the salt belongs to the triclinic space group P1[combining macron] with a relatively high density of 1.912 g cm-3 under 298 K. The properties of the salt are discussed in detail. The thermal decomposition behaviors of the salt are tested, indicating that the salt has good thermal stability with a decomposition temperature above 200 °C. The enthalpy of formation for the salt is dependent on the combustion heat date measured by oxygen bomb calorimetry with a result of 425.6 kJ mol-1, which is the same level as TKX-50, and four times higher than that of RDX. The detonation pressure (P) and detonation velocity (D) of the salt are calculated as 8931 m s-1 and 36.1 GPa, which are higher than those of RDX. In addition, the impact and friction sensitivities are tested through a relevant standard method with a result of 28 J and 120 N, which are better than those of TKX-50. We can draw the conclusion that the salt could provide a promising future in use as a kind of insensitive explosive alternative. The discovery also contributes significantly to the expansion and application of the chemistry of 1H,1H-5,5-bitetrazole-1,1-diolate, as well as N-heterocyclic compounds.

Green Energetic Nitrogen-rich Salts of 1,1'-Dinitramino-5,5'-Bistetrazolate

A series of nitrogen-rich energetic salts of 1,1-dinitramino-5,5-bistetrazolate (DNABT) guanidinium (1), aminoguanidinium (2), diaminoguanidinium (3), triaminoguanidinium (4), diaminouronium (5), 3,4-diamino-1,2,4-triazolium (6), and ethylenediammonium (7) was synthesized by a metathesis strategy and characterized by elemental analysis, mass spectrometry, and IR spectroscopy as well as single-crystal X-ray diffraction and differential scanning calorimetry (DSC). The natural bond orbitals (NBOs) and electrostatic potentials (ESPs) were further computed for a better understanding of the structures of the DNABT molecule. The heats of formation were calculated based on the Born-Haber energy cycle. The detonation parameters were evaluated by using the EXPLO5 program, and the sensitivities were measured according to BAM standers. These new salts exhibit highly positive heats of formation (407.0-1377.9u2005kJu2009mol-1 ) and good thermal stabilities (180-211u2009°C). Most of these compounds possess detonation velocities comparable to RDX and acceptable detonation pressures. The high volumes of explosion gases of the salts 3 and 4 (921 and 933u2005Lu2009kg-1 , respectively) further support their power as explosives. The enhancing performances, the fact of being free of metals, and the more moderate sensitivities than K2 DNABT, suggest that the salts 4 (D=8851u2005mu2009s-1 , P=29.0u2005GPa), 5 (D=9053u2005mu2009s-1 , P=32.3u2005GPa), and 6 (D=8835u2005mu2009s-1 , P=30.2u2005GPa) might be potential environmentally friendly energetic materials.

Synthesis, crystal structure and properties of a new 1D polymeric nitrogen-rich energetic complex {TAG[Li(BTO)(H2O)]}n based on 1H,1′H-5,5′-bitetrazole-1,1′-diolate

A novel energetic coordination polymer, or a new anionic metal–organic framework (MOF), of {TAG[Li(BTO)(H2O)]}n based on 1H,1′H-5,5′-bitetrazole-1,1′-diolate (BTO), was developed based on the reaction of BTO with triaminoguanidinium chloride (TAG·HCl) and lithium hydroxide (LiOH), and characterized by elemental analysis and IR spectroscopy. The crystal structure was determined by single-crystal X-ray diffraction measurements. Results show that the polymer belongs to the monoclinic space group C/2c with a density of 1.678 g cm−3, and the cell parameters were as follows: a = 15.6560(5) A, b = 6.3323(19) A, c = 23.8140(7) A, β = 91.342(3)°, V = 2360.20(12) A3, Z = 8, F(000) = 1232. The central lithium cation was coordinated by two N atoms, two O atoms from BTO ligands, and the O atom from one coordination water molecule. The infinite 1D-zigzag-chains were made up of the central lithium cations linked by bridging-chelating BTO ligands. The thermal decomposition of {TAG[Li(BTO)(H2O)]}n was studied based on technologies of differential scanning calorimetry (DSC) and thermogravimetry-differential thermogravimetry (TG-DTG). The non-isothermal kinetics parameters were calculated through the Kissinger and the Ozawa–Doyle methods, and the apparent activation energy was 236.6 kJ mol−1 and 233.1 kJ mol−1, while the critical temperature of thermal explosion was 231.6 °C. The enthalpy of formation for the polymer was also determined through the combustion heat data, measured by using oxygen bomb calorimetry, as 29.5 kJ mol−1. Additionally, the sensitivities towards impact and friction were assessed with relevant standard methods, the results show that the polymer can act as an insensitive explosive with its high nitrogen-content.

A 1D cadmium complex with 3,4-diamino-1,2,4-triazole as ligand: synthesis, molecular structure, characterization, and theoretical studies

An energetic complex, [Cd2(μ-Cl)4Cl2(DATr)2]n (1) (DATr = 3,4-diamino-1,2,4-triazole), was synthesized from DATr·HCl and cadmium(II) chloride. The product was characterized by Fourier transform infrared spectroscopy analysis, elemental analysis, X-ray diffraction analysis, and differential scanning calorimeter (DSC) analysis. The central cadmium(II) ions in 1 are six-coordinate twisted octahedral structures, which are made up of 1D chains linked by bridging chlorides. The results of the DSC analysis suggest the temperature of decomposition to be above 503.15 K. Furthermore, the kinetic properties of decomposition are studied by Kissinger’s and Ozawa–Doyle’s methods, and the calculated average activation is 166.5 kJ M−1, which means the complex is stable under normal conditions. In addition, the energy of combustion was measured by oxygen bomb calorimetry. The critical temperature of thermal explosion and parameters of thermodynamics of 1 were calculated. The periodic structure of 1 has been calculated based on the density functional theory. The theoretical results explain the electronic structure and thermal dynamic properties. Graphical abstract A new 1D Cd complex based on 3,4-diamino-1,2,4-triazole was synthesized and structurally characterized. Its thermal stability, non-isothermal kinetics analysis, and theoretical calculation were studied, and energy of combustion was also measured.

Controllable explosion: fine-tuning the sensitivity of high-energy complexes

Tuning the sensitivity of energetic materials has always been a research topic of interest. A lot of attention has been paid on changing the ligands previously used in traditional high energy density materials (HEDMs). Recently, we have stepped further along this path by thinking from another angle, i.e., changing the metal centre. Herein, we report 4 transition metal complexes bearing the 1,5-diaminotetrazole ligand, which have similar structures but drastically different sensitivities. These differences are apparently due to the different metal centres used.