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Energetic Metal-Organic Framework (EMOF) compounds have gained significant attention in recent years as a hot research topic in the fields of explosives and propellants. This article provides an overview of the latest research progress of EMOFs in various areas, including heat-resistant explosives, burning rate catalysts and initiating explosives. It discusses the recent development trends of high-energy EMOFs, such as high-dimensional and solvent-free structural design, simplified and scalable synthesis conditions, environmentally friendly manufacturing processes with tunable structures, high-energy, low-sensitivity and multifunctional target products. The challenges and issues faced by EMOFs in heat-resistant explosives, burning rate catalysts and initiating explosives are presented. Furthermore, the key research directions for future applications of EMOFs in the fields of explosives and propellants are discussed, including solvent-free high-dimensional EMOFs design and synthesis, precise modulation of EMOFs molecular composition and pore structure, improvement of accurate prediction methods for physicochemical properties of high-energy EMOFs, low-cost large-scale production and development of multifunctional composite EMOFs as energetic materials, exploration of influencing factors, and comprehensive study on the application of novel and high-performance multifunctional EMOFs.

Background: Systemic lupus erythematosus (SLE) is a complex autoimmune disorder that affects multiple organ systems, with a higher prevalence among women in their reproductive years. The disease's multifactorial etiology involves genetic, environmental, and hormonal components. Recent studies have highlighted the potential impact of dietary factors, particularly unsaturated fatty acids, on the modulation of SLE due to their anti-inflammatory properties. This meta-analysis aims to evaluate the association between unsaturated fatty acid consumption and the risk, progression, and clinical manifestations of SLE, providing evidence-based guidance for dietary management., Methods: We conducted a comprehensive search across major medical databases up to January 2024, focusing on studies that examined the intake of unsaturated fatty acids and the impact of such intake on SLE. Using the PICOS (population, intervention, comparator, outcomes, study design) framework, we included randomized controlled trials and case-control studies, assessing outcomes such as SLE activity, measured by SLE Disease Activity Index (SLEDAI) or the British Isles Lupus Assessment Group (BILAG) index, inflammation biomarkers. Studies were analyzed using either a fixed- or random-effects model based on heterogeneity ( I 2 statistic), with sensitivity analyses performed to assess the robustness of the findings., Results: Our search included 10 studies, encompassing a wide variety of designs and populations. The meta-analysis showed that a diet rich in unsaturated fatty acids is significantly associated with a reduction in SLEDAI scores (pooled SMD) of -0.36, 95% CI: -0.61 to -0.11, p = 0.007, indicating a beneficial effect on disease activity. Additionally, we found that unsaturated fatty acid intake has a significant impact on HDL levels, suggesting a positive effect on lipid profiles. However, no significant effects were observed on levels of the inflammatory marker IL-6 or other lipid components (LDL and cholesterol). With minimal heterogeneity among studies ( I 2 ≤ 15%), sensitivity analysis confirmed the stability and reliability of these results, highlighting the potential role of unsaturated fatty acids in SLE management., Conclusions: This meta-analysis suggests that dietary intake of unsaturated fatty acids may play a positive role in reducing SLE activity and may significantly affect HDL levels without having significant effects on inflammation markers or other lipid profiles. These findings support the inclusion of unsaturated fatty acids in the dietary management of SLE patients, although further research is required to refine dietary recommendations and explore the mechanisms underlying these associations., Competing Interests: The authors declare no conflicts of interest.

In our pursuit of promoting the green development of energetic materials and harnessing their functional benefits, we strive to address the inherent contradiction between energy and low sensitivity. In this regard, we have successfully constructed an azotriazole framework via environmentally friendly electrochemistry with a satisfactory yield of 62.3%. Through a simple ion-exchange process, we then synthesized nitrogen-rich salt derivatives of azotriazolone. These nitrogen-rich salts exhibit a wide range of nitrogen contents, ranging from 32.16 to 68.80%. Remarkably, crystallographic analysis of these green energy-containing salts reveals substantial advantages in terms of thermodynamic stability and low sensitivity. Experimental investigations have demonstrated a positive relationship between the nitrogen content and the pyrothermal performance of the azotriazolone derivatives. Of particular significance is compound 5 , a triaminoguanidine salt, which exhibits an exceptionally high nitrogen content of 68.80%. It displays a detonation pressure of 28.2 GPa and a detonation velocity of 7939.4 m s -1 . Moreover, the derivatives of azotriazolone salts demonstrate the formation of nitrogen-rich compounds, characterized by insensitive properties, attributed to the hydrogen-bonded network structures resulting from anion-cation interactions. With the exception of compound 5 , which exhibits a friction sensitivity of 252 N, the remaining derivatives show a similar value of approximately 360 N. This suggests that azotriazolone serves as a promising material possessing both stabilizing properties and better detonation performance, thereby providing a favorable platform for the synthesis of novel compounds with advantageous properties.

Based on N-B bonds, a novel strategy was developed for improving the energetic performance of tetrazoles. By employing the amino neighboring group participation, the azolyl borane compound 7 was selectively constructed, which exhibited excellent stability in water and air. This strategy solved the acidity problem of tetrazole as well as increasing the heat of detonation and combustion by 25% and 36%, respectively. Through laser ignition experiments, it also improved the combustion performance of tetrazoles. In DSC experiments, thermal decomposition temperatures of N-B covalent compounds were elevated as well. In an electrostatic potential calculation and sensitivity test, N-B covalent compounds exhibited good sensitivity (IS > 40 J and FS > 360 N). Through TG-DSC-FTIR-MS and in situ IR experiments, decomposition products were investigated to determine the next optimization stage for heat of detonation. It offered a significant potential for development to incorporate the N-B bond into nitrogen-rich compounds.

The structural motif of biazoles is the predominant substructure of many natural products, pharmaceuticals, and organic materials. Considerable efforts have focused on synthesizing these compounds; however, a limited number of processes have been reported for the efficient formation of biazoles. Herein, we report a "pre-join" approach for the dehydrogenative synthesis of biazoles, which are challenging to prepare using conventional methods. A bench-stable and easily synthesized pyrazine-based group is critical for this transformation. This strategy enables the homocoupling of biazoles and the heterocoupling of two different azoles. Due to the broad substrate scope, this strategy exhibits potential for use in other fields, such as medicine, materials, and natural product chemistry., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Safety concerns remain a bottleneck for the application of 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)/1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX) cocrystal. Melamine-formaldehyde (MF) resin was chosen to fabricate CL-20/HMX cocrystal-based core-shell composites (CH@MF composites) via a facile in situ polymerization method. The resulted CH@MF composites were comprehensively characterized, and a compact core-shell structure was confirmed. The effects of the shell content on the properties of the composites were explored as well. As a result, we found that, except for CH@MF-2 with a 1% shell content, the increase in shell content led to a rougher surface morphology and more close-packed structure. The thermal decomposition peak temperature improved by 5.3 °C for the cocrystal enabled in 1.0 wt% MF resin. Regarding the sensitivity, the CH@MF composites exhibited a significantly reduced impact and friction sensitivity with negligible energy loss compared with the raw cocrystal and physical mixtures due to the cushioning and insulation effects of the MF coating. The formation mechanism of the core-shell micro-composites was further clarified. Overall, this work provides a green, facile and industrially potential strategy for the desensitization of energetic cocrystals. The CH@MF composites with high thermal stability and low sensitivity are promising to be applied in propellants and polymer-bonded explosive (PBX) formulations.

The structural units of amino-/cyano-substituted furazans and furoxans played significant roles in the synthesis of nitrogen-rich energetic compounds. This account focused on the synthetic strategies toward nitrogen-rich energetic compounds through the transformations based on cyanofurazan/furoxan structures, including 3-amino-4-cyanofurazan, 4-amino-3-cyano furoxan, 3,4-dicyanofurazan, and 3,4-dicyanofuroxan. The synthetic strategies toward seven kinds of nitrogen-rich energetic compounds, such as azo (azoxy)-bridged, ether-bridged, methylene-bridged, hybrid furazan/furoxan-tetrazole-based, tandem furoxan-based, hybrid furazan-isofurazan-based, hybrid furoxan-isoxazole-based and fused framework-based energetic compounds were fully reviewed, with the corresponding reaction mechanisms toward the nitrogen-rich aromatic frameworks and examples of using the frameworks to create high energetic substances highlighted and discussed. The energetic properties of typical nitrogen-rich energetic compounds had also been compared and summarized., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Zhai, She, Wang, Zhang and Wang.)

Two energetic bicyclic scaffolds (furazan-isoxazole and furazan-1,3,4-oxadiazole) were constructed via different cyclization reactions. Based on the energetic bicyclic scaffolds, the energetic compounds, 3-(4-nitraminofurazan-3-ly)-isoxazole-5-methylnitrate 1c and 5-(4-nitraminofurazan-3-ly)-1,3,4-oxadiazole-2-methylnitrate 2c, were designed and synthesized in good yields. Because of the acidity of nitramine, the corresponding energetic ionic salts, ammonium 3-(4-nitraminofurazan-3-ly)isoxazole-5-methylnitrate 1d and ammonium 5-(4-nitraminofurazan-3-ly)-1,3,4-oxadiazole-2-methylnitrate 2e, were also obtained and well characterized, their structures were further determined by X-ray single crystal diffraction. To have a better understanding of the structure-property relationships of furazan-bicyclic scaffolds and nitrate groups, their thermal behaviors, detonation performances and the sensitivities were investigated via differential scanning calorimetry (DSC), ESP analysis, Hirshfeld surfaces calculation, EXPLO5 program and BAM standard techniques. Compared with those of ammonium 5-(4-nitraminofurazan-3-ly)-1,2,4-oxadiazole-2-methylnitrate 3e, the results show that all these methyl nitrate energetic compounds based on bicyclic scaffolds of furazan-isofurazan exhibit good detonation performances and extraordinary insensitivities. As supported by experimental and theoretical data, the formation of energetic ionic salts causes an increase of the weak interactions, significantly improving the thermal performance over 110 °C., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Molecular perovskites are promising practicable energetic materials with easy access and outstanding performances. Herein, we reported the first comparative thermal research on energetic molecular perovskite structures of (C 6 H 14 N 2 )[NH 4 (ClO 4 ) 3 ], (C 6 H 14 N 2 )[Na(ClO 4 ) 3 ], and (C 6 H 14 ON 2 )[NH 4 (ClO 4 ) 3 ] through both calculation and experimental methods with different heating rates such as 2, 5, 10, and 20 °C/min. The peak temperature of thermal decompositions of (C 6 H 14 ON 2 )[NH 4 (ClO 4 ) 3 ] and (C 6 H 14 N 2 ) [Na(ClO 4 ) 3 ] were 384 and 354 °C at the heating rate of 10 °C/min, which are lower than that of (C 6 H 14 N 2 )[NH 4 (ClO 4 ) 3 ] (401 °C). The choice of organic component with larger molecular volume, as well as the replacement of ammonium cation by alkali cation weakened the cubic cage skeletons; meanwhile, corresponding kinetic parameters were calculated with thermokinetics software. The synergistic catalysis thermal decomposition mechanisms of the molecular perovskites were also investigated based on condensed-phase thermolysis/Fourier-transform infrared spectroscopy method and DSC-TG-FTIR-MS quadruple technology at different temperatures.

Domain-related knowledge promoted high-throughput cage scaffold screening from the ZINC15 database containing over 130 000 scaffolds and cooperated with combinatorial design to alleviate the lack of cage energetic materials. A dozen candidates were discovered that show excellent energy and safety performance, confirming the effectiveness of our strategy.

A new structural type for melt cast materials was designed by linking nitrotetrazole ring with 1,2,4-oxadiazole through a N-CH 2 -C bridge for the first time. Three N-CH 2 -C linkage bridged energetic compounds, including 3-((5-nitro-2H-tetrazol-2-yl) methyl)-1,2,4-oxadiazole (NTOM), 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-(trifluoromethyl)-1,2,4 -oxadiazole (NTOF) and 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-amine-1,2,4-oxadiazole (NTOA), were designed and synthesized through a two-step reaction by using 2-(5-nitro-2H-tetrazole -2-yl)acetonitrile as the starting material. The synthesized compounds were fully characterized by NMR ( 1 H, 13 C), IR spectroscopy and elemental analysis. The single crystals of NTOM, NTOF and NTOA were successfully obtained and investigated by single-crystal X-ray diffraction. The thermal stabilities of these compounds were evaluated by DSC-TG measurements, and their apparent activation energies were calculated by Kissinger and Ozawa methods. The crystal densities of the three compounds were between 1.66 g/cm 3 (NTOA) and 1.87 g/cm 3 (NTOF). The impact and friction sensitivities were measured by standard BAM fall-hammer techniques, and their detonation performances were computed using the EXPLO 5 (v. 6.04) program. The detonation velocities of the three compounds are between 7271 m/s (NTOF) and 7909 m/s (NTOM). The impact sensitivities are >40 J, and the friction sensitivities are >360 N. NTOM, NTOF and NTOA are thermally stable, with decomposition points > 240 °C. The melting points of NTOM and NTOF are 82.6 °C and 71.7 °C, respectively. Hence, they possess potential to be used as melt cast materials with good thermal stabilities and better detonation performances than TNT.

Dinitropyrazole is an important structure for the design and synthesis of energetic materials. In this work, we reported the first comparative thermal studies of two representative dinitropyrazole-based energetic materials, 4-amino-3,5-dinitropyrazole (LLM-116) and its novel trimer derivative (LLM-226). Both the experimental and theoretical results proved the active aromatic N-H moiety would cause incredible variations in the physicochemical characteristics of the obtained energetic materials. Thermal behaviors and kinetic studies of the two related dinitropyrazole-based energetic structures showed that impressive thermal stabilization could be achieved after the trimerization, but also would result in a less concentrated heat-release process. Detailed analysis of condensed-phase systems and the gaseous products during the thermal decomposition processes, and simulation studies based on ReaxFF force field, indicated that the ring opening of LLM-116 was triggered by hydrogen transfer of the active aromatic N-H moiety. In contrast, the initial decomposition of LLM-226 was caused by the rupture of carbon-nitrogen bonds at the diazo moiety.

Weak interfacial interactions remain a bottleneck for composite materials due to their weakened performance and restricted applications. The development of core-shell engineering shed light on the preparation of compact and intact composites with improved interfacial interactions. This review addresses how core-shell engineering has been applied to energetic materials, with emphasis upon how micro-energetic materials, the most widely used particles in the military field, can be generated in a rational way. The preparation methods of core-shell structured explosives (CSEs) developed in the past few decades are summarized herein. Case studies on polymer-, explosive- and novel materials-based CSEs are presented in terms of their compositions and physical properties (e.g., thermal stability, mechanical properties and sensitivity). The mechanisms behind the dramatic and divergent properties of CSEs are also clarified. A glimpse of the future in this area is given to show the potential for CSEs and some suggestions regarding the future research directions are proposed.

Diversity-oriented synthesis of energetic pyrimidine structures with geminal explosophoric groups of geminal dinitro and azido-nitro groups via a novel reductive cleavage and oxidative coupling strategy is reported. Fluorine has also been introduced for the first time based on the nucleophilic coupling process. The obtained energetic pyrimidines are investigated via X-ray diffraction and theoretical techniques of electrostatic potential and proton affinity calculations. Both experimental and calculation results showed impressive detonation performances and good application prospects of the energetic pyrimidine structures. Among them, DNNC exhibited great promise as a green oxidant in solid propellant formulations to replace ammonium perchlorate (AP). TNHA (ρ = 1.79 g cm-3, D = 8537 m s-1, P = 32.69 Gpa) and TNHF (ρ = 1.85 g cm-3, D = 8517 m s-1, P = 32.64 Gpa) proved to be ideal candidates for high explosives due to their high densities and detonation properties. Moreover, TNHA could also be applied as a potential underwater explosive owing to its great heat of formation.

Oxidation of nitrogen-rich aromatic heterocycles has a significant impact on the development of energetic materials. 2,4,6-Triamino-1,3,5-triazine-1,3-dioxide (MDO) is a promising insensitive energetic backbone obtained from melamine under strong oxidation conditions with impressive thermal behaviors and detonation performances. In this paper, MDO was prepared with improved yields of 85% and its thermal behavior, non-isothermal decomposition kinetics and gas products were investigated in detail. The corresponding decomposition mechanism was also deduced by applying the TG-DSC-FTIR-MS technique for the first time. The decomposition temperature of MDO reaches 300 °C and the apparent activation energy of MDO ( E ) calculated by the Kissinger and Ozawa method proved to be 303.63 and 279.95 kJ mol -1 , indicating great thermal stability. Three new monoanionic energetic salts with impressively improved properties were achieved based on the basicity of MDO with yields of >80%. Their thermal decomposition temperatures proved to be higher than 230 °C and their densities are in the range of 1.75-1.89 g cm -3 . The calculations and experiments show that their detonation velocities ( v D : 8711-9085 m s -1 ) are comparable to or exceed those of RDX ( D : 8795 m s -1 ) while the sensitivities to impact (IS: 23-27 J) and friction (FS: >240 J) are much lower., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Organic inner salt structures are ideal backbones for heat-resistant energetic materials and systematic studies towards the thermal properties of energetic organic inner salt structures are crucial to their applications. Herein, we report a comparative thermal research of two energetic organic inner salts with different tetraazapentalene backbones. Detailed thermal decomposition behaviors and kinetics were investigated through differential scanning calorimetry and thermogravimetric analysis (DSC-TG) methods, showing that the thermal stability of the inner salts is higher than most of the traditional heat-resistant energetic materials. Further studies towards the thermal decomposition mechanism were carried out through condensed-phase thermolysis/Fourier-transform infrared (in-situ FTIR) spectroscopy and the combination of differential scanning calorimetry-thermogravimetry-mass spectrometry-Fourier-transform infrared spectroscopy (DSC-TG-MS-FTIR) techniques. The experiment and calculation results prove that the arrangement of the inner salt backbones has great influence on the thermal decompositions of the corresponding energetic materials. The weak N4-N5 bond in "y-" pattern tetraazapentalene backbone lead to early decomposition process and the "z-" pattern tetraazapentalene backbone exhibits more concentrated decomposition behaviors.

In this paper, twelve 1,3-dinitrohexahydropyrimidine-based energetic compounds were designed by introducing various explosopheres into hexahydropyrimidine skeleton. Their geometric and electronic structures, heats of formation (HOFs), energetic performance, thermal stability and impact sensitivity were discussed. It is found that the incorporation of electron-withdrawing groups (-NO 2 , -NHNO 2 , -N 3 , -CH(NO 2 ) 2 , -CF(NO 2 ) 2 , -C(NO 2 ) 3 ) improves HOFs of the derivatives and all the substituents contribute to enhancing the densities and detonation properties (D, P) of the title compounds. Therein, the substitution of -C(NO 2 ) 3 features the best energetic performance with detonation velocity of 9.40 km s -1 and detonation pressure of 40.20 GPa. An analysis of the bond dissociation energies suggests that N-NO 2 bond may be the initial site in the thermal decompositions for most of the derivatives. Besides, -ONO 2 and -NF 2 derivatives stand out with lower impact sensitivity. Characters with striking detonation properties (D = 8.62 km s -1 , P = 35.08 GPa; D = 8.81 km s -1 , P = 34.88 GPa), good thermal stability, and acceptable impact sensitivity (characteristic height H 50 over 34 cm) lead novel compounds 5,5-difluoramine-1,3-dinitrohexahydropyrimidine (K) and 5-fluoro-1,3,5-trinitrohexahydropyrimidine (L) to be very promising energetic materials. This work provides the theoretical molecular design and a reasonable synthetic route of L for further experimental synthesis and testing.

Although energetic regioisomers have attracted intensive attention due to their interesting structure-property correlation, their effective synthesis and accurate identification has remained very difficult. In this paper, we synthesized two energetic regioisomers, namely 3-(4-aminofurazan-3-yl)-4-(4-nitrofurazan-3-yl)furoxan (ANFF-34) and 4-(4-aminofurazan-3-yl)-3-(4-nitrofurazan-3-yl)furoxan (ANFF-43), via a controllable strategy with improved yields of 32% and 38%, respectively. The structures of ANFF-34 and ANFF-43 were unambiguously identified using comparative studies of 15 N NMR and single-crystal X-ray diffraction. Moreover, their thermal behaviours, and non-isothermal thermodynamic parameters were systematically investigated. Both ANFF-34 ( T m : 116.2 °C, T d : 255.4 °C) and ANFF-43 ( T m : 106.2 °C, T d : 255.6 °C) have similar thermal decomposition processes to that of DNTF. The superior performances of ANFF-34 ( ρ : 1.8 g cm -3 , D : 8214 m s -1 , P : 30.5 GPa, IS > 40 J) and ANFF-43 ( ρ : 1.7 g cm -3 , D : 7868 m s -1 , P : 27.0 GPa, IS > 40 J) indicate their great potential to be used as melt-cast carrier explosives. This study provides a solid foundation for the design and synthesis of new energetic compounds through isomer effects., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

3,3'-Bi(1,2,4-oxadiazole)-5,5'-diylbis(methylene)dinitrate (BOM) is a liquid phase carrier for melt cast explosives that is expected to replace TNT. The combination of a conjugated 1,2,4-oxadiazole backbone and nitrate ester groups endows BOM with both good energetic performance and impressive insensitivity. In this paper, the thermal behaviors of BOM were investigated using a TG-DSC synchronous thermal analyzer, proving that BOM is basically non-volatile under heating and melting processes. The apparent activation energy of BOM calculated by the Kissinger method was 158.2 kJ mol -1 at atmospheric pressure, which is higher than that of DNTF at atmospheric pressure and TNT at 2 MPa, indicating good thermal stability at low temperatures. The thermal decomposition mechanism of BOM was studied through both DSC-MS and in situ FTIR technologies. The low eutectic characteristics of BOM and DNTF were also investigated carefully and the best ratio of BOM/DNTF was 40/60 with a melting point at 75.5 °C. Finally, the detonation performances of TNT/HMX, BOM/HMX and BOM/DNTF(40/60)/HMX explosive formulations were calculated, showing that the detonation performances of the latter two formulations were significantly higher than that of TNT/HMX., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The design and preparation of new nitrogen-rich heterocyclic compounds are of considerable significance for the development of high-performing energetic materials. By combining nitrogen-rich tetrazole and oxygen-rich furoxan, a linear C-C bonded pentaheterocyclic energetic compound, 3,4-bis(3-tetrazolylfuroxan-4-yl) furoxan (BTTFO), was synthesized using a facile and straightforward method. Comprehensive X-ray analysis reveals the key role of hydrogen bonds, π-π interactions, and short contacts in the formation of dense packing of BTTFO and explains why a long chain-shaped molecule has a high density. This multicyclic structure incorporating three furoxan and two tetrazole moieties results in an exceptionally high heat of formation (1290.8 kJ mol -1 ) and favorable calculated detonation performances ( v D , 8621 m s -1 , P , 31.5 GPa). The interesting structure and fascinating properties demonstrated the feasibility of a linear multicyclic approach as a high-energy-density skeleton. Additionally, the thermodynamic parameters, electrostatic potential (ESP), and frontier molecular orbitals were also studied to get a better understanding of structure-property correlations., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

The introduction of fluorodinitromethyl energetic groups is an efficient strategy to improve the performances of energetic materials. In this paper, an insensitive energetic compound 6-(fluorodinitromethyl)-3-nitro-1,2,3,4-tetrahydro-1,3,5-triazine (FMTNT) was designed and synthesized based on the modification of 1,3,5-triazine backbone via the nitration-rearrangement, reduction and fluorination sequence. The single crystal of FMTNT was firstly obtained and determined, meanwhile, this novel structure was also fully characterized by the methods of IR, 1 H NMR, 13 C NMR, 19 F NMR and elemental analysis. Studies on thermal behaviors and detonation performances of FMTNT were also carried out through differential scanning calorimetry (DSC-TG) approach and EXPLO5 program, respectively. The decomposition temperature of FMTNT is found to be at 157.5 °C via thermal chemical analysis and the detonation performances were proved to be good, with a detonation velocity of 8624.8 m s -1 and detonation pressure of 29.1 Gpa. Furthermore, the experimental results showed that impact and friction sensitivity reaches 20 J and 240 N, even less sensitive than TNT, indicating a broad perspective in the application of insensitive explosives and propellants., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

4,8-Dihydrodifurazano[3,4- b , e ]pyrazine (DFP) is one kind of parent compound for the synthesis of various promising difurazanopyrazine derivatives. In this paper, eleven series of energetic salts composed of 4,8-dihydrodifurazano[3,4- b , e ]pyrazine-based anions and ammonium-based cations were designed. Their densities, heats of formation, energetic properties, impact sensitivity, and thermodynamics of formation were studied and compared based on density functional theory and volume-based thermodynamics method. Results show that ammonium and hydroxylammonium salts exhibit higher densities and more excellent detonation performance than guanidinium and triaminoguanidinium salts. Therein, the substitution with electron-withdrawing groups (-NO 2 , -CH 2 NF 2 , -CH 2 ONO 2 , -C(NO 2 ) 3 , -CH 2 N 3 ) contributes to enhancing the densities, heats of formation, and detonation properties of the title salts, and the substitution of -C(NO 2 ) 3 features the best performance. Incorporating N-O oxidation bond to difurazano[3,4- b , e ]pyrazine anion gives a rise to the detonation performance of the title salts, while increasing their impact sensitivity meanwhile. Importantly, triaminoguanidinium 4,8-dihydrodifurazano[3,4- b , e ]pyrazine (J4) has been successfully synthesized. The experimentally determined density and H 50 value of J4 are 1.602 g/cm 3 and higher than 112 cm, which are consistent with theoretical values, supporting the reliability of calculation methods. J4 proves to be a thermally stable and energetic explosive with decomposition peak temperature of 216.7 °C, detonation velocity 7732 m/s, and detonation pressure 25.42 GPa, respectively. These results confirm that the derivative work in furazanopyrazine compounds is an effective strategy to design and screen out potential candidates for high-performance energetic salts.

Density, detonation property, and sensitivity may be the most valued features when evaluating an energetic material. By reasoning structure-property relationships, a nitro-free planar energetic material with high nitrogen and oxygen content, 7-hydroxy-difurazano[3,4- b :3',4'- f ]furoxano[3″,4″- d ]azepine ( 4 ), was synthesized using a unique and facile approach. The structure was fully characterized by IR and NMR spectra, elemental analysis, differential scanning calorimetry (DSC), and single-crystal X-ray diffraction. The expected properties of 4 , including a high density of 1.92 g cm -3 , high detonation velocity of 8,875 m s -1 , and low mechanical sensitivities (impact sensitivity, 21 J and friction sensitivity, >360 N), confirm our strategy. Interestingly, the single-crystal structures of 4 reveal expected face-to-face and edge-to-face π-interactions in the crystal stacking. The remarkable differences in crystal stacking of 4 provide unequivocal evidence that face-to-face π-π interactions contribute significantly to closer assembly and higher density.

1,3-oxazinane is an ideal framework for advanced energetic materials because of its compact skeleton and the presence of several modifiable sites. However, investigations on characterization and performance of 1,3-oxazinane energetic compounds are extremely limited. Two heterocyclic 1,3-oxazinane molecules were synthesized under different Mannich condensation processes and further reacted to form nitro- and azide-substituted energetic compounds 3,5,5-trinitro-1,3-oxazinane (TNTON) and 5-azido-3,5-dinitro-1,3-oxazinane (ADTON), in good yields. Interestingly, the two energetic molecules showed distinct physical properties. ADTON shows an impressive glass transition temperature (Tg) as low as -46 °C with high density, which is highly suitable for rate-accelerating materials. TNTON exhibits good thermal stabilities (melting point of 89 °C and a decomposition point of 231 °C) and highly insensitive behavior (38 J, 360 N). The theoretical detonation pressure of TNTON is ca. 63 % higher than that of TNT, indicating broad application prospects in melt-cast explosives., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

It is of current development to construct high-performance energetic compounds by aggregation of energetic groups with dense arrangement. In this study, a hydrogen-free high-density energetic 3,4-bis(3-nitrofuroxan-4-yl)furoxan (BNTFO-I) was designed and synthesized in a simple, and straightforward manner. Its isomer, 3,4-bis(4-nitrofuroxan-3-yl)furoxan (BNTFO-IV), was also obtained by isomerization. The structures of BNTFO-I and BNTFO-IV were confirmed by single-crystal X-ray analysis for the first time. Surprisingly, BNTFO-I has a remarkable calculated crystal density of 1983 g cm -3 at 296 K, which is distinctly higher than BNTFO-IV (1.936 g cm -3 , 296 K), and ranks highest among azole-based CNO compounds yet reported. It is noteworthy that BNTFO-I exhibits excellent calculated detonation properties (v D , 9867 m s -1 , P, 45.0 GPa). The interesting configuration differences of BNTFO-I and BNTFO-IV provide insight into the design of new advanced energetic materials.

The replacement of traditional polynitroarylenes by their fluorinated derivatives has attracted great attention due to the improvements on detonation performance caused by the fluorine effect. A straightforward synthesis of three novel fluorinated nitrotoluenes with different degrees of nitration was achieved under selected high temperatures. The fluorine exerted remarkable influence on the nitration process through the electron-withdrawing effect and a mechanism of the transformation was proposed according to the experimental results. Thermal decomposition behavior of the fluorinated nitrotoluenes was investigated by differential scanning calorimetry and all the compounds showed ideal low melt points for the melt-cast process. X-ray analysis of the fluorinated derivatives were carried out as well as density functional calculations to establish the electronic density and electrostatic potential on the molecular surface of the optimized structures. The good thermal and detonation properties make the newly developed fluorinated nitrotoluenes possible replacements for trinitrotoluene and dinitrotoluene in the formation of melt-cast energetic materials., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Molecular dynamics simulation was performed on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), 2,4-dinitro-2,4-diazapentane (DNDAP), and CL-20/DNDAP cocrystal and composite under COMPASS force field at different temperatures. The binding energy ( E bind ), radial distribution function (RDF), trigger bond length, cohesive energy density (CED) and mechanical properties were studied and compared. The results show that the binding energy of the cocrystal is evidently higher than that of the composite at the same temperature. RDF analysis reveals that hydrogen bonds and vdW forces between CL-20 and DNDAP exist in both CL-20/DNDAP cocrystal and composite, and the interactions in the cocrystal are stronger than those in the composite. The maximum trigger bond length decreases in the order ε-CL-20 > CL-20/DNDAP composite > CL-20/DNDAP cocrystal. Moreover, the rigidity and stiffness of the cocrystal and composite decrease compared to that of CL-20, while the ductility and elasticity are better than that of the two pure components. These results demonstrate that CL-20/DNDAP cocrystal might be very promising in explosive applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, the growth morphologies of 1,1-diamino-2,2-dinitroethene (FOX-7) in vacuum and solvent conditions were investigated by molecular dynamics simulation. The modified attachment energy (MAE) model and occupancy model were used separately to predict the crystal morphology by calculating relative growth rate of different crystal faces in H 2 O/NMP and DMSO/AC solvent system. The calculated results show that the (0 1 1) face and (1 0 1) face are the most important crystal face in both two solvents towards the MAE model and the occupancy model, respectively. Compared with that from the MAE model, the predicted morphologies from the occupancy model are in better agreement with the experimental results. Radial distribution function (RDF) analyses were employed to demonstrate that the hydrogen bonds and vdW interactions play the dominant role between solvent molecules and FOX-7 surfaces. The above results allow us to understand the role played by solvents and solute molecules on growth morphologies of FOX-7 crystals., (Copyright © 2018 Elsevier Inc. All rights reserved.)

To obtain a deeper understanding of the process involved in the synthesis of N -nitrodiethanolamine dinitrate (DINA), in this work we carried out systematic studies on the transformation and stability of the N -nitration liquid and DINA. The thermal decomposition processes and dynamic characteristics for both the N -nitration liquid and DINA were carried out by thermal analysis methods and the mechanism for the decrease of stability of the N -nitration liquid was proposed according to experimental results. Mechanical stimulation of the N -nitration liquid and DINA were also studied by friction and impact sensitivity testing. The experimental results showed that the N -nitration liquid is highly sensitive to temperature and can decompose easily when the reaction temperature increases. However, mechanical sensitivity of the N -nitration was demonstrated to be much lower than that of DINA. Therefore, precise thermal control is the key factor to ensure safety during the preparation of DINA.

1-Amino-3,5-dinitro-1,2,4-triazole (ADNT) was prepared using an efficient N-amination process. Three novel catenated N 6 energetic derivatives of ADNT, which contain 1,1'-azobis(3,5-dinitro-1,2,4-triazole) (ABDNT), 1,1'-azobis(3-chloro-5-nitro-1,2,4-triazole) (ABCNT) and 1,1'-azobis(3,5-diazido-1,2,4-triazole) (ABDAT), were synthesized from N-amino oxidative-coupling reactions of ADNT. All compounds were fully characterized by 1 H and 13 C nuclear magnetic resonance spectroscopies, infrared spectroscopy, elemental analysis, mass spectrum, as well as differential scanning calorimetry (DSC). The crystal structure of compound ABCNT was confirmed by single-crystal X-ray diffraction showing an extensive conjugated structure. The densities of energetic derivatives ranged from 1.71 to 1.93 g cm -3 , and all compounds have positive heats of formation in the range of 774.8 to 2150.8 kJ mol -1 . Based on the measured densities and calculated heats of formation, theoretical performance calculations, including detonation pressures (29.6-42.4 GPa) and detonation velocities (8.22-9.49 km s -1 ) were carried out using the Gaussian 09 program and Kamlet-Jacobs equations, and they compared favorably with those of TNT and RDX. These properties make them potentially competitive as new high energy-density compounds., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The hydrolysis mechanism and the kinetics of using 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione (NMP) to prepare the representative insensitive energetic material 1,1-diamino-2,2-dinitroethylene (FOX-7) in a nitric-sulfuric acid system are systematically investigated via a density functional theory (DFT) method. The impact of the co-existing acidic group of HSO 4 - as well as the solvent effects of the mixed acids on the hydrolysis of NMP are elucidated and discerned, and the proposed catalysis and promotion of the hydrolysis of NMP with HSO 4 - are verified. The HSO 4 - -catalyzed hydrolysis pathway is more favorable than the direct pathway as well as the H 2 O-catalyzed hydrolysis, indicating that HSO 4 - may be a promising catalyst for the preparation of FOX-7 in a mixed acid system. The present study is expected to provide a better understanding of the hydrolysis of NMP, and will significantly help with better preparation of FOX-7 and other nitro-energetic materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The persistent challenge in the field of energetic materials is how to synthesize energetic compounds with high density, high heat of detonation and outstanding detonation performance by gathering the maximum number of energetic groups in the smallest volume. The self-assembly of energetic groups with metal ions is crucially influenced by the solvent conditions. Here, the reaction of Cu(NO 3 ) 2 ·3H 2 O with 3-nitro-1H-1,2,4-triazole (Hntz) in aqueous ammonia under hydrothermal conditions via a self-assembly strategy yielded the Cu(i) energetic compound [Cu(ntz)] n (1). In order to further enhance the energetic property, an N 3 - anion was introduced into the system and two Cu(ii) energetic compounds, [Cu(ntz)(N 3 )(DMF)] n (2) and [Cu(ntz)(N 3 )(H 2 O)] n (3), were successfully synthesized under different solvent conditions. Structural analyses show that compound 1 features a compacted 3D structure framework and compounds 2-3 exhibit 1D butterfly-like chain structures. The experimental results reveal that 1 possesses attractive thermal stability up to 315.0 °C and 1-3 present excellent insensitivity. Importantly, the heat of detonation of compound 2 has been factually improved due to the abundant energetic bonds in the coordinated DMF molecules compared to 1 and lots of energies are taken away during the release of the coordinated solvent molecules in the low temperature range resulting in the obvious decreases in detonation pressure and detonation velocity for compounds 2-3, which further exemplifies that the subtle change of reaction conditions may have a crucial effect on the resultant detonation performance. In addition, the detonation performances of 1-3 calculated by both a simple method for metal-containing explosives developed by Pang et al. and the commercial program EXPLO5 v6.01, are discussed in detail.

3-Oxy-furoxanate is immobilized in a heterometallic energetic metal-organic framework (MOFs). Two furoxan-based MOFs ([Ag 2 K 4 (BDOFO)(BDFO) 2 (H 2 O) 6 ] n , [K 2 (BDFO)] n ) and a salt ([(BDFO 2- )(NH 2 NH 3 + ) 2 (H 2 O)] n (BDOFO 2- =4,5-bis(dinitromethyl)-3-oxy-furoxanate, BDFO 2- =4,5-bis(dinitromethyl)-furoxanate) are synthesized and their energetic performance evaluated. This study outlines the systematic investigation of detonation performance of 3-oxy-furoxan and its derivatives., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)