Energetic coordination polymers (ECPs) based on tetrazole N-oxides: green nitrogen-rich energetic complexes of variable dimensions

In recent years, it has been demonstrated that the energetic properties of many tetrazole-containing compounds can be enhanced through the formation of the corresponding N-oxides. The introduction of N-O groups increases the oxygen balance of tetrazole compounds, while providing additional coordination sites and enriching the coordination modes between tetrazole compounds and metal ions. The introduction of O atoms alters the polarity of the substance from N to N-O, the packing and density increase and therefore the detonation velocity (VD) and pressure (P) also increase. Based on this, energetic coordination polymers (ECPs) with tetrazole N-oxides serving as ligands possess extremely high research value. In this paper, we aim to summarize the existing ECPs based on tetrazole N-oxides briefly and discuss their advantages, emphasizing their excellent stability and application prospects.

Research progress of EMOFs-based burning rate catalysts for solid propellants

Energetic Metal Organic Frameworks (EMOFs) have been a hotspot of research on solid propellants in recent years. In this paper, research on the application of EMOFs-based burning rate catalysts in solid propellants was reviewed and the development trend of these catalysts was explored. The catalysts analyzed included monometallic organic frameworks-based energetic burning rate catalysts, bimetallic multifunctional energetic burning rate catalysts, carbon-supported EMOFs burning rate catalysts, and catalysts that can be used in conjunction with EMOFs. The review suggest that monometallic organic frameworks-based burning rate catalysts have relatively simple catalytic effects, and adding metal salts can improve their catalytic effect. Bimetallic multifunctional energetic burning rate catalysts have excellent catalytic performance and the potential for broad application. The investigation of carbon-supported EMOFs burning rate catalysts is still at a preliminary stage, but their preparation and application have become a research focus in the burning rate catalyst field. The application of catalysts that can be compounded with EMOFs should be promoted. Finally, environmental protection, high energy and low sensitivity, nanometerization, multifunctional compounding and solvent-free are proposed as key directions of future research. This study aims to provide a reference for the application of energetic organic burning rate catalysts in solid propellants.

Energetic Bimetallic MOF: A Promising Promoter for Ionic Liquid Hypergolic Ignition

A bimetallic MOF, CoNi(EIM)₂(DCA)₂ (1), containing an energetic 1-ethylimidazole (EIM) ligand and a hypergolic linker, dicyandiamide (DCA), was synthesized via a facile method. A fascinating three-dimensional reticular architecture was observed by single-crystal X-ray diffraction in this bimetallic MOF, whereas the corresponding monometallic compounds Co(EIM)₄(DCA)₂ (2) and Ni(EIM)₄(DCA)₂ (3) were in the mononuclear coordination mode. Uniformly distributed Co and Ni were observed in the bimetallic MOF crystals by SEM-EDS elemental mapping. Bimetallic MOF 1 was thermally stable and insensitive to mechanical stimuli and possessed an excellent energetic density (22.37 kJ·g^-1). Using 1 as a hypergolic promoter, the ignition delay time of 1-butyl-3-methylimidazolium dicyanamide (BMIM DCA) was reduced from 53 to 37 ms, better than that of 2 and 3 as promoters, due to the synergistic catalysis of the bimetal. Furthermore, the thermal decomposition mechanisms of BMIM DCA with 1, 2, and 3 were studied by differential scanning calorimetry (DSC). 1 had the best catalytic performance in BMIM DCA thermolysis with a decrease in the decomposition temperature from 314.5 to 308.0 °C and a decrease in the activation energy by 16.3%. All results shed light on the better catalytic effect of the bimetallic MOF on ionic liquid hypergolic ignition than monometallic coordination compounds.

Thermodynamics and Catalytic Properties of Two Novel Energetic Complexes Based on 3-Amino-1,2,4-triazole-5-carboxylic Acid

For energetic materials (EMs), the key point of the present research is to improve the energetic property and reduce sensitivity. In this work, two new energetic complexes, Mn(atzc)₂(H₂O)₂·2H₂O (1) and Zn(atzc)₂(H₂O) (2) (Hatzc = 3-amino-1,2,4-triazole-5-carboxylic acid), were synthesized by solvent evaporation and diffusion methods, respectively. The structural analyses illustrate that 1 and 2 exhibit zero-dimensional structural units, which are linked by hydrogen-bonding interactions to give three-dimensional supramolecular architectures. For complexes 1 and 2, the detonation velocities (D) are 10.4 and 10.2 km·s^-1 and detonation pressures (P) are 48.7 and 48.6 GPa, respectively. They are higher than most of the reported EMs, which present prominent detonation characteristics. In addition, two complexes can accelerate the thermal decomposition of ammonium perchlorate and exhibit excellent catalytic activity. Therefore, the two complexes can serve as a new class of promising EMs, which have potential application in the design of new high-efficiency solid catalysts.

Construction of highly energetic metal-organic frameworks with a nitrobenzene derivative

Three metal–organic frameworks [CdL(DMF)]n 1, {[CuL(H2O)(DMF)]•DMF•0.5H2O}n 2 and [Nd(HL)L(DMF)3]n 3 have been synthesized with a nitrobenzene derivative 4-((5-hydroxy-2,4-dinitrophenoxy)methyl)-3-nitrobenzoic acid (H2L). Compound 1 has a dense three-dimensional framework with 1D Cd...

Oxygen-Enriched Metal-Organic Frameworks Based on 1-(Trinitromethyl)-1H-1,2,4-Triazole-3-Carboxylic Acid and Their Thermal Decomposition and Effects on the Decomposition of Ammonium Perchlorate

Energetic metal-organic frameworks (EMOFs) with a high oxygen content are currently a hot spot in the field of energetic materials research. In this article, two series of EMOFs with different ligands were obtained by reacting 1-(trinitromethyl)-1H-1,2,4-triazole-3-carboxylic acid (tntrza) with metal iodide and metal nitrate, respectively. Furthermore, their structure, thermal stability, thermal decomposition kinetics, and energy performance are fully characterized. The research results revealed that the synthesized EMOFs possess a wide range of density (ρ = 1.88∼2.595 g cm^-3), oxygen balance (OB(CO₂) = -21.1∼ -4.3%), and acceptable energy performance (D = 7.73∼8.74 km s^-1 and P = 28.1∼41.1 GPa). The difference in OB(CO₂) caused by the ligand structure and metal properties has a great impact on the distribution of gas-phase products after the decomposition of these EMOFs. Noteworthy, [Ag(tntrza)]_n is particularly prominent among these EMOFs, not only because of its excellent detonation performance (D = 8.74 km s^-1 and P = 41.1 GPa) endowed by its extremely high density (ρ = 2.595 g cm^-3) and oxygen balance (OB(CO₂) = -4.3%) but also because of its effective catalytic effect on the decomposition of ammonium perchlorate (AP). This article broadens the horizon for the study of oxygen-enriched EMOFs with catalytic effects and helps understand the mechanism of thermal decomposition of EMOFs with nitroform and dinitro groups.

Constructing Strategies and Applications of Nitrogen-Rich Energetic Metal–Organic Framework Materials

The synthesis of energetic metal–organic frameworks (EMOFs) with one-dimensional, two-dimensional and three-dimensional structures is an effective strategy for developing new-generation high-energy-density and insensitive materials. The basic properties, models, synthetic strategies and applications of EMOF materials with nitrogen-rich energetic groups as ligands are reviewed. In contrast with traditional energetic materials, EMOFs exhibit some interesting characteristics, like tunable structure, diverse pores, high-density, high-detonation heat and so on. The traditional strategies to design EMOF materials with ideal properties are just to change the types and the size of energetic ligands and to select different metal ions. Recently, some new design concepts have come forth to produce more EMOFs materials with excellent properties, by modifying the energetic groups on the ligands and introducing highly energetic anion into skeleton, encapsulating metastable anions, introducing templates and so on. The paper points out that appropriate constructing strategy should be adopted according to the inherent characteristics of different EMOFs, by combining with functional requirements and considering the difficulties and the cost of production. To promote the development and application of EMOF materials, the more accurate and comprehensive synthesis, systematic performance measurement methods, theoretical calculation and structure simulation should be reinforced.

Adsorption of tetranitromethane in zeolitic imidazolate frameworks yields energetic materials

Absorption of tetranitromethane in the zeolitic imidazolate frameworks ZIF-8 and ZIF-70 is a facile route to borderline primary/secondary explosives that contain no toxic heavy metals.

A solvent-free dense energetic metal-organic framework (EMOF): to improve stability and energetic performance via in situ microcalorimetry

It is a tremendous challenge to prepare solvent-free dense energetic metal-organic frameworks (EMOFs), hence also to improve their stability and energetic performance. In this study, based on in situ microcalorimetry, an interpenetrating EMOF without solvent molecules, [Cu(tztr)]_n (1, H₂tztr = 3-(tetrazol-5-yl)triazole) was obtained, possessing high stability (T_dec = 360 °C) and outstanding energetic properties (ΔH_det = 7.53 kcal cm^-3, D = 8.429 km s^-1, P = 40.02 GPa).

Design and fabrication of energetic metal-organic framework [Cu(ntz)]n films with high energy-density and stability

In this work, for the first time, we have successfully prepared energetic metal-organic framework [Cu(ntz)]_n films by integrating electrochemical deposition and solvothermal growth. With its excellent energy, stability and ignition performances, the [Cu(ntz)]_n film has potential application in microelectromechanical systems (MEMS) to achieve functional nanoenergetics-on-a-chip.

Self-assembled energetic 3D metal–organic framework [Na8(N5)8(H2O)3]n based on cyclo-N5–

A new 3D zeolite-like MOF [Na₈(N₅)₈(H₂O)₃]_n with an enhanced stability has been successfully synthesized by the self-assembly of Na⁺ with cyclo-N₅⁻ ligands.

Three novel Co(ii)/Ni(ii)-based coordination polymers as efficient heterogeneous catalysts for dye degradation

Three novel Co(ii)/Ni(ii)-based coordination polymers have been synthesized and characterized. Compound 2 shows a rare 2D + 2D heterogeneous framework. Compound 3 is a chiral 0-D molecular complex driven by the solvent-assisted homochiral helix. The photocatalytic oxidation activities and mechanism have been studied.

Explosives in the Cage: Metal-Organic Frameworks for High-Energy Materials Sensing and Desensitization

An overview of the current status of coordination polymers and metal-organic frameworks (MOFs) pertaining to the field of energetic materials is provided. The explosive applications of MOFs are discussed from two aspects: one for detection of explosives, and the other for explosive desensitization. By virtue of their adjustable pore/cage sizes, high surface area, tunable functional sites, and rich host-guest chemistry, MOFs have emerged as promising candidates for both explosive sensing and desensitization. The challenges and perspectives in these two areas are thoroughly discussed, and the processing methods for practical applications are also discussed briefly.

Self-assembly of silver(i)-based high-energy metal–organic frameworks (HE-MOFs) at ambient temperature and pressure: synthesis, structure and superior explosive performance

Two HE-MOFs, {Ag₂(DNMAF)(H₂O)₂}_n (1) and {Ag₂(DNMAF)}_n (2), were prepared using K₂DNMAF in a mild self-assembly strategy.

Green primary energetic materials based on N-(3-nitro-1-(trinitromethyl)-1H-1,2,4-triazol-5-yl)nitramide

A series of green primary energetic materials based on N-(3-nitro-1-(trinitromethyl)-1,2,4-triazol-5-yl)nitramide were synthesized and structurally characterized.