Synthesis,Crystal Structure,and Thermal Behavior of a Novel Insensitive Energetic Cocrystal Composed of 3,3′‐Bis(1,2,4‐oxadiazole)‐5,5′‐dione and 4‐Amino‐1,2,4‐triazole

A novel insensitive energetic cocrystal consisting of 3,3′‐bis(1,2,4‐oxadiazole)‐5,5′‐dione and 4‐amino‐1,2,4‐triazole in a 1:2 molar ratio was prepared and characterized. The structure of this cocrystal was characterized by single‐crystal X‐ray diffraction. The crystal structure of the cocrystal is a monoclinic system with P1 space group. Properties of the cocrystal studied included thermal decomposition and detonation performance. This cocrystal has a crystal density of 1.689 g · cm^–3 at 173 K and good detonation performance (D = 6940 m · s^–1, P = 20.9 GPa). Moreover, measured impact and friction sensitivities (IS > 40 J, FS > 360 N) show that it can be classified as an insensitive energetic material. Its thermodynamic properties indicate that it has moderate thermal stability with a sharp exothermic peak (244 °C, 5 K · min^–1) and a high critical temperature of thermal explosion (523 K). In view of the observations above, it may serve as a promising alternative to known explosives such as TNT.     

Synthesis,Structural and Energetic Properties of Copper(II) Perchlorate Complex with Aminoguanidine

The complexation of copper(II) perchlorate with aminoguanidine hemesulfate (AGHS) yield related mononuclear complex bis(aminoguanidine)copper(II) perchlorate; [Cu(AG)₂](ClO₄)₂ ( I ). The characterization of complex I was done by elemental analysis, electronic spectra, IR studies, and X‐ray diffraction. From analytical data, a stoichiometry of 1:2 of metal to ligand was determined for the complex. The structure consists of centrosymmetric square planar [Cu(AG)₂]²⁺ cations and perchlorate counterions. The Cu^II atom is four‐coordinate by two imine N atoms and two amine N atoms from two aminoguanidine ligands, forming a slightly distorted square‐planar coordination. In the crystal structure, molecules are linked through intermolecular N–H ··· O hydrogen bonds, forming a network. The thermal decomposition process of this complex was investigated through differential scanning calorimetry (DSC) and the sensitivities toward impact and friction were assessed using a BAM drophammer and a BAM friction tester.     

Synthesis and Properties of [Ba(CHZ)(BT)(H2O)2]n as a New Energetic Coordination Compound

In order to enhance the thermal stability of the barium salt of 5,5′‐bistetrazole (H₂BT), carbohydrazide (CHZ) was used to build [Ba(CHZ)(BT)(H₂O)₂]_n as a new energetic coordination compound by using a simple aqueous solution method. It was characterized by FT‐IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. The crystal belongs to the monoclinic P2₁/c space group [a = 8.6827(18) Å, b = 17.945(4) Å, c = 7.2525 Å, β = 94.395(2)°, V = 1126.7(4) ų, and ρ = 2.356 g · cm^–3]. The Ba^II cation is ten‐coordinated with one BT^2–, two shared carbohydrazides, and four shared water molecules. The thermal stabilities were investigated by differential scanning calorimetry (DSC) and thermal gravity analysis (TGA). The dehyration temperature (T_dehydro) is at 187 °C, whereas the decomposition temperature (T_d) is 432 °C. Non‐isothermal reaction kinetics parameters were calculated by Kissinger's method and Ozawa's method to work out E_K = 155.2 kJ · mol^–1, lgA_K = 9.25, and E_O = 158.8 kJ · mol^–1. The values of thermodynamic parameters, the peak temperature (while β → 0) (T_p0 = 674.85 K), the critical temperature of thermal explosion (T_b = 700.5 K), the free energy of activation (ΔG^≠ = 194.6 kJ · mol^–1), the entropy of activation (ΔS^≠ = –66.7 J · mol^–1), and the enthalpy of activation (ΔH^≠ = 149.6 kJ · mol^–1) were obtained. Additionally, the enthalpy of formation was calculated with density functional theory (DFT), obtaining Δ_fH°₂₉₈ ≈ 1962.6 kJ · mol^–1. Finally, the sensitivities toward impact and friction were assessed according to relevant methods. The result indicates the compound as an insensitive energetic material.     

Synthesis and Investigation of Energetic Boron Compounds for Pyrotechnics

The energetic boron esters tris(1‐ethyl‐5‐aminotetrazolyl) borate, tris(2‐ethyl‐5‐aminotetrazolyl) borate, tris(1‐ethyltetrazolyl) borate, tris(2‐ethyltetrazolyl) borate, and tris(2‐(3‐nitro‐1, 2,4‐triazolyl)ethyl) borate were synthesized and analyzed by NMR and IR spectroscopy, elemental analysis, and mass spectrometry. Two tetracoordinate borates potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were synthesized and fully characterized as well. Moreover, the energetic and thermal properties of the energetic boron esters and tetracoordinate borates were determined. The ¹¹B NMR chemical shifts of potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were calculated and compared to the experimental values. Tris(1‐ethyl‐5‐aminotetrazolyl) borate was tested as colorant in pyrotechnic formulations with respect to the combustion behavior and color properties as well as the energetic and thermal properties.     

Synthesis and Characterization of Energetic Salts of the (C4N122–) Dianion

3, 6‐Bis(tetrazol‐5‐yl)‐1, 2, 4, 5‐tetrazine is a nitrogen‐rich energetic compound readily prepared and a strong dibasic acid. By the reaction with energetic bases such including hydroxylamine, triaminoguanidine, hydrazine, and diaminourea, multiple ionic energetic materials were prepared and characterized for the first time. Both chemical (multinuclear NMR, Infrared, Raman, MS, etc) as well as explosive (Impact, Friction, Static sensitivities) properties are reported. The materials prepared, with the exception of the silver salt, which is a primary explosive, fall into the classification of low‐sensitivity energetic materials due to desensitizing hydration waters. Calculated explosive performances using the EXPLO5 computer code are also reported.     

Synthesis and Properties of [Cd(HTRTR)2(H2O)4](HTNR)2 as an Energetic Complex

The energetic complex, [Cd(HTRTR)₂(H₂O)₄](HTNR)₂ {HTRTR = 4‐[3‐(1,2,4‐triazol‐yl)‐1,2,4‐triaozle; HTNR^– = styphnic acid anion) was synthesized and characterized by FT‐IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. It crystallizes triclinic in space group P$\bar{1}$ [a = 8.156(2) Å, b = 8.374(2) Å, c = 13.267(4) Å, α = 84.925(11)°, β = 87.016(11)°, γ = 63.683(5)°, V = 808.9(4) ų, ρ = 1.940 g · cm^–3]. The Cd^II ion is six‐coordinate with two HTRTRs and four water molecules. The thermal stabilities were investigated by differential scanning calorimetry (DSC). Non‐isothermal reaction kinetic parameters were calculated by Kissinger's and Ozawa‐Doyle's methods to obtain E_K = 144.0 kJ · mol^–1, lgA_K = 14.22, and E_O = 144.3 kJ · mol^–1. The values of thermodynamic parameters, the peak temperature while β→0 (T_p0), free energy of activation (ΔG^≠), entropy of activation (ΔS^≠), and enthalpy of activation (ΔH^≠) were obtained. Additionally, the enthalpy of formation was calculated by Hess's law on the basis of the experimental constant‐volume heat of combustion measured by bomb calorimetry, obtaining Δ_fH°₂₉₈ = 4985.5 kJ · mol^–1. Finally, the sensitivities toward impact and friction were assessed according to relevant methods. The result indicates it as an insensitive energetic material.     

3‐Nitramino‐4‐nitrofurazan: Enhancing the Stability and Energetic Properties by Introduction of Alkylnitramines

Nitration of 3‐amino‐4‐nitrofurazan with N₂O₅ yielded the corresponding nitramine. 3‐Nitramino‐4‐nitrofurazan is a very promising explosive regarding detonation performance but it suffers from its hygroscopicity, low thermal stability, and high sensitivity to external stimuli. The introduction of other nitramine groups either by alkylation with 1‐chloro‐2‐nitrazapropane or by combination of two 3‐nitramino‐4‐nitrofurazans yielded the corresponding more stable and non‐hygroscopic open‐chain nitramines. Their molecular structures were investigated by single‐crystal X‐ray diffraction. The remarkable difference of their impact sensitivities were evaluated by calculation of their electrostatic potential of the molecular surfaces. Furthermore, the detonation parameters and combustion parameters of the open‐chain nitramines were computed with the EXPLO5 (v. 6.02) computer code.     

Two Energetic Ionic Salts of en·PA·H2O and en·TNR: Preparation,Structural Characterization,and Properties

Energetic salts of en · PA · H₂O and en · TNR were synthesized by using ethylenediamine and picric acid (PA) or 2,4,6‐trinitroresorcinol (TNR) as raw materials, and their structures were characterized by elemental analysis and FT‐IR spectroscopy. Single crystals of the title salts were obtained and their structures were determined by single‐crystal X‐ray diffraction. The thermal decomposition behaviors were investigated by DSC and TG‐DTG technologies, furthermore the non‐isothermal kinetic parameters and enthalpies of formation for the salts were calculated. Their combustion heats were measured by oxygen bomb calorimetry and their enthalpies of formation were also calculated based on the combustion heat data. In addition, the detonation pressure (P) and detonation velocities (D) of the salts were predicted by using the K‐J equations. The results indicated that the title salts have potential applications in the field of energetic materials.     

Synthesis,Characterization, and Energetic Properties of Nitroso Compounds

Sodium and potassium methyl(nitroso)amide (M[CH₃N₂O], M = Na ( 1 ), K ( 2 )) were prepared by the reaction of monomethylhydrazine with iso‐pentyl nitrite or n‐butyl nitrite and a suitable metal ethoxide (M[CH₃CH₂O], M = Na, K) in an ethanol‐ether mixture. The reaction of monomethylhydrazine with a small excess of iso‐pentyl nitrite or n‐butyl nitrite and in the absence of a metal ethoxide led to the formation of N‐nitroso‐N‐methylhydrazine (CH₃(NO)N–NH₂, ( 3 )). Alternatively, compound 3 was prepared by the amination reaction of 1 or 2 using the sodium salt of HOSA in ethanol solution. Compounds 1–3 were characterized using elemental analysis, differential scanning calorimetry, mass spectrometry, vibrational (infrared and Raman) and UV spectroscopy and multinuclear (¹H, ¹³C and ¹⁵N) NMR spectroscopy. For compounds 1–3 , several physical and chemical properties of interest and sensitivity data were measured and for compound 3 thermodynamic and explosive properties are also given. Additionally, the solid‐state structure of compound 3 was determined by single‐crystal X‐ray analysis and the structures of the cis‐ and trans‐[CH₃N₂O]^– anions and that of 3 were optimized using DFT calculations and used to calculate the NBO charges.     

Synthesis and Characterization of a New Energetic Salt based on Dinitramide

The development of new ionic salt as green propellants is one of intense investigations to replace toxic N, N′‐dimethylhydrazine. A new energetic salt N, N′,N′′‐tri(propan‐2‐ylidene)methanetriamium dinitramide (NTAGDN) based on dinitramide was synthesized by reacting silver dinitramide with triaminoguanidinium chloride. The structure of this new energetic salt was confirmed by single‐crystal X‐ray diffraction, elemental analysis, Fourier transform infrared spectrometry, ultraviolet‐visible spectrophotometry, and nuclear magnetic resonance spectroscopy. NTAGDN crystallizes in the orthorhombic space group R$\bar{3}$ . Thermal decomposition was studied by differential scanning calorimetry, differential thermal analysis, and thermogravimetric tandem infrared spectrometry. Results indicated that NTAGDN exhibited excellent resistance to thermal decompositions of up to 470 K and incurred an 80.54 % mass loss between 450 and 523 K via exothermic decomposition. The kinetic parameters of NTAGDN thermal decomposition were also obtained from the differential thermal analysis data by Kissinger's method with E_a = 125.46 kJ · mol^–1. Moreover, based on the Kamlet‐Jacobs formula, the detonation velocity and detonation pressure of NTAGDN were calculated as 6.3 km · s^–1 and 15 GPa, respectively.     

Syntheses,Crystal Structures,and Properties of Two Novel CL‐20‐based Cocrystals

In recent years, cocrystallization has emerged as an effective way of tuning the properties of compounds and has been widely used in the field of energetic materials. In this study, we have prepared two novel cocrystals of CL‐20 and methylimidazole, including a 1:2 CL‐20 / 2‐mercapto‐1‐methylimidazole ( 1 ) and a 1:4 CL‐20 / 4‐methyl‐5‐nitroimidazole ( 2 ). Cocrystal 1 has good physical and detonation properties (ρ₁ = 1.652 g · cm^–3, D₁ = 7073 m · s^–1, P₁ = 21.6 GPa); however, cocrystal 2 shows higher properties (ρ₂ = 1.680 g · cm^–3, D₂ = 7945 m · s^–1, P₂ = 27.4 GPa). The performance of both cocrystals is better than those of TNT. Thermal performance suggests that both the cocrystals have moderate thermal stabilities. Cocrystal 1 decomposes at 164.9 °C and cocrystal 2 has an exothermic peak at 221 °C. Both cocrystals are insensitive energetic explosives (IS > 40 J, FS > 360 N). Methylimidazole compounds are rarely used as coformers to form cocrystals with CL‐20, which possess good properties for a range of potential applications. Herein, we provide new possible directions for enriching cocrystal speciation.     

Insensitive and Thermostable Energetic Materials Based on 3‐Ureido‐4‐tetrazole‐furazan: Synthesis,Characterization, and Properties

Energetic salts composed of ureido, furazan, and tetrazole were prepared by simple and efficient chemical routes to explore new insensitive and thermostable energetic materials. 3‐Ureido‐4‐tetrazole‐furazan ( 3 ) and its ammonium salt ( 5 ) and hydrazinium salt ( 6 ) were confirmed by single‐crystal X‐ray diffraction. The thermal stabilities of the synthesized salts were studied using differential scanning calorimetry, and the detonation performances of these salts were calculated using EXPLO 5 V6.01. All the salts exhibit good thermal stability (Td: 148–259 °C) and mechanical sensitivities (IS > 40 J, FS > 360 N), and their detonation velocities range from 7316 to 8655 m · s^–1. Compounds 6 and 10 are potential candidates as novel insensitive and heat‐resistant explosives because of their high detonation temperatures of 247 and 256 °C, good detonation velocities of 8432 and 8523 m · s^–1, and good detonation pressures of 25.6 and 26.8 GPa.     

Ammonia Oxide as a Building Block for High-Performance and Insensitive Energetic Materials

3,5-Dinitrimino-1,2,4-triazole ( 2 ) with three protons has the potential of deprotonation to form energetic salts. Neutralization of 2 with 50 % hydroxylamine in varying molar ratios leads to the formation of the corresponding mono/dihydroxylammonium energetic salts. Additionally compound 5 , an ammonia oxide adduct of dihydroxylammonium 3,5-dinitramino-1,2,4-triazolate, was prepared when excess hydroxylamine was used. The structures of 3 – 5 are supported by single-crystal X-ray diffraction. The energetic properties of the new materials are competitive. Utilization of ammonia oxide adducts in hydroxylammonium energetic salts could lead to future practical applications as energetic materials.     

Magnesium Azotetrazole‐1,1′‐dioxide: Synthesis and Promising Properties of Green Insensitive Energetic Materials

Magnesium azotetrazole‐1,1′‐dioxide ( 1 ) was first prepared and intensively characterized by single‐crystal X‐ray diffraction, IR spectroscopy, mass spectrometry, elemental analysis, and DSC measurements. The heat of formation was calculated using the atomization energy method based on quantum chemistry and the heat of detonation was also predicted. The NBO analysis was performed for inspecting charge distributions. The sensitivities towards impact and friction were tested using the BAM standard. The high detonation performance (5289 kJ · kg^–1), good thermal stabilities (245.5 °C) and excellent insensitivity (39.2 J and >360 N) as well as clean decomposition products supports it of great interest as a promising candidate of green insensitive energetic materials.     

Energetic cuprous azide complex: synthesis,crystal structure,and characterization

An energetic cuprous azide complex, [Cu₂(2apyz)(N₃)₂] _n (1) (2apyz?=?2-aminopyrazine), has been synthesized through hydrothermal method by utilizing the reducibility of H₃PO₃ and structurally characterized by single-crystal X-ray diffraction. Complex 1 has a 2-D layer structure constructed from copper(I) bridged by azide and pyrazine. Catalysis research shows 1 can promote the burning rate of the main component of rocket propellant.     

Synthesis and Characterization of a New Energetic Plasticizer: Acyl-Terminated GAP

A new energetic plasticizer, acyl-terminated glycidyl azide polymer (GAP), was synthesized through the reaction between 2,4,6-trinitrobenzoyl (TNB) chloride and GAP. The TNB-GAP structure was confirmed by FT-IR, UV-vis, ¹H NMR, and ¹³C NMR. The glass transition temperature (T _g ) of TNB-GAP was evaluated by differential scanning calorimetry (DSC), and the thermal stability of TNB-GAP was tested by thermogravimetric analysis (TGA). DSC traces showed that TNB-GAP had a T _g of ?46.01°C. TGA curves showed that the thermo-oxidative degradation of TNB-GAP in air was a two-step reaction, and the percentage of degraded TNB-GAP nearly reached 100% at 650°C. Exothermic decomposition reaction kinetic parameters of TNB-GAP were also studied using the non-isothermal DSC method. Results indicated that the values of apparent activation energy of TNB-GAP were 80.16 and 162.92 kJ/mol, and the values of the pre-exponential constant were 1.75 × 10¹⁰ and 1.22 × 10¹⁶.     

Preparation,Crystal Structure,and Thermal Analysis of Two Energetic Salts Based on Nitro Phenolic Compounds with Diamino‐glyoxine

As a key research objective for environmentally friendly energetic materials, energetic salts without heavy metal have received wide attention. The energetic salts DAG · PA · H₂O ( 1 ) and DAG · TNR · H₂O ( 2 ) were synthesized by using diamino‐glyoxine (DAG) and picric acid (PA) or 2, 4,6‐trinitro‐resorcinol (TNR) as raw materials, and their structures were characterized by elemental analysis, FT‐IR, ¹H NMR, and ¹³C NMR spectroscopy. Single crystals of the title salts were cultured and their structures were determined by X‐ray single‐crystal diffraction. Both salts belong to the triclinic space group P1 with density values of 1.764 and 1.751 g · cm^–3, respectively. The thermal decomposition behaviors of both salts were investigated by differential scanning calorimetry (DSC), the non‐isothermal kinetic parameters and the critical temperature of thermal explosion were calculated. The heats of formation for the salts were also determined through the combustion heats date measured by using the oxygen bomb calorimetry. In addition, the detonation pressure (P) and detonation velocities (D) of the salts were predicted by using the K‐J equations, and their sensitivities towards impact and friction were tested. The results indicated that the title salts have potential applications in the field of energetic materials.     

含能配位聚合物[Cu(tza)2]n的晶体结构、热分析、感度和催化性能

以碱式碳酸铜和四氮唑乙酸在水中反应制备得到四唑乙酸铜(II)含能配位聚合物, 并培养出单晶. 运用元素分析, FT-IR分析和X-射线单晶衍射对标题配合物的组成和结构进行了全面的表征. 采用差示扫描量热分析(DSC)和热重-微分热重分析(TG-DTG)研究了标题配合物的热分解过程, 表明标题配合物的热分解主要包含三个放热峰. 用Kissinger和Ozawa-Doyle法对标题配合物的第一放热分解过程进行了动力学研究, 计算得到其活化能为356.1 kJ/mol. 对配合物的撞击、摩擦、火焰感度和5s爆发点测试表明该配合物具有一定的感度, 有望作为含能材料应用于相关领域. 同时研究了标题配合物对RDX热分解的影响, 结果表明: 标题配合物可以使RDX的放热分解峰的温度提前16.4 ℃,分解速度加快, 对RDX具有良好的催化作用.     

Synthesis,Crystal Structure,and Thermal Properties of the Energetic Coordination Compound [Co(DAT)2(H2O)4](HTNR)2·2H2O (DAT = 1,5‐diaminotetrazole)

A new coordination complex, [Co(DAT)₂(H₂O)₄](HTNR)₂ · 2H₂O [DAT = 1,5‐diaminotetrazole, HTNR = 2,4,6‐trinitroresorcinol (styphnic acid)], was obtained in high yield and characterized by elemental analysis and Fourier‐transform infrared (FT‐IR) spectroscopy. The molecular structure of [Co(DAT)₂(H₂O)₄](HTNR)₂ · 2H₂O in the crystalline state is determined by X‐ray crystallography is as follows: monoclinic, C2/c, a = 19.216(3) Å, b = 5.4992(8) Å, c = 30.418(5) Å, β = 104.500(5), V = 3112.0(8) ų, Z = 4, ρ_calc. = 1.851 g · cm^–3, R₁ = 0.0271 and wR₂ = (all data) 0.0674. The central cobalt(II) cation is coordinated by two nitrogen atoms of two DAT and four oxygen atoms of four H₂O ligand molecules to form a six‐coordinate and slightly distorted octahedral structure. Extensive intermolecular hydrogen bonds link molecular units of [Co(DAT)₂(H₂O)₄(HTNR)₂ · 2H₂O together to form a 3D net structure with pore canals. The thermal decomposition mechanism for the title compound was predicted based on DSC, TG‐DTG, and FT‐IR analyses and non‐kinetic parameters of the first exothermic process were estimated by applying the Kissinger, Starink, and Ozawa–Doyle methods.