Energetic Metal-organic Frameworks Research Articles

Solvent Free Potassium 3,5-dinitro-6-oxo-1,6-dihydropyrazin-2-olate 3D EMOF as Thermally Stable Energetic Material.

Heat-resistant explosives play a vital role in indispensable applications. For this, we have synthesized a novel, three-dimensional, solvent-free energetic metal-organic framework (EMOF) potassium 3,5-dinitro-6-oxo-1,6-dihydropyrazin-2-olate (KDNODP) straightforwardly. The synthesized EMOF was characterized through IR, NMR spectroscopy, elemental analysis, and differential scanning calorimetry studies. Furthermore, single-crystal X-ray diffraction provided a complete description of KDNODP. It exhibits a three-dimensional EMOF structure with remarkably balanced properties such as high density (2.11 g cm-3), excellent thermal stability (291 °C), good detonation performance (8127 m s-1 and 26.94 GPa) and low mechanical sensitivity (IS=35 J; FS=360 N) than the commonly used heat-resistant explosives HNS (density=1.74 g cm-3; VOD=7164 m s-1, DP=21.65 GPa, IS=5 J) as well as the similar reported energetic potassium MOFs. To gain insights into the packing and intermolecular interactions, the Hirshfeld surface and a 2D fingerprint analysis were examined. Additionally, scanning electron microscopy was used to investigate the particle size and morphological characteristics of KDNODP. These outcomes highlight a successful method for creating 3D EMOF based on a six-membered heterocycle as a potential heat-resistant energetic material.

Advanced oxidation processes of persulfate coupled with sequencing batch reactor activated sludge process (AOPs-SBR): Biodegradability and toxicity analysis of degradation intermediates

Although carbon-based catalysts are of great significance for potential application in advanced oxidation processes of persulfate, the biotoxicity and biodegradability of degradation intermediates of organic pollutants have been rarely reported. Herein, carbon-based nanofiber materials are prepared by electrospinning energetic metal–organic framework (EMOF) and ferric acetylacetonate, where the puff up of the EMOF creates hierarchical porous structure during high-temperature pyrolysis and provides sufficient space to expose Fe/N active sites. When organic pollutant tetracycline (TTCH) as target contaminant, energetic MOF derived carbon/Fe nanofiber in 900C named ECFe-9, which exhibits larger specific surface area (546.8 m2/g) and higher reaction rate constant k value (0.186 min−1) than that of in 700, 800 and 1000 °C. The biotoxicity of degradation intermediates is investigated by toxicity simulation. The biodegradability is analyzed by using advanced oxidation coupled with sequencing batch reactor activated sludge process (AOPs-SBR). This study provides a new perspective for advanced oxidation processes of persulfate as pretreatment methods for aerobic biochemical degradation of persistent organic pollutants.

Self-Assembly Method for Synthesizing High-Dimensional EMOFs with High Stability and Laser Response.

Dimension and solvent molecules affect the performance of energetic metal-organic frameworks (EMOFs). High-dimensional EMOFs are usually characterized by high stability and low sensitivity due to their complex network structure. However, solvent molecules affect the detonation performance of EMOFs, and these molecules may be removed at low temperatures, resulting in structural collapse and affecting the stability of EMOFs. In this work, zero-dimensional (0D) Co(AFTO)2·(H2O)2 (EMOF 1) and Ni(AFTO)2·(H2O)2 (EMOF 2) with coordinated water molecules and [Co(AFTO)2]n·EtOH (EMOF 3) and [Ni(AFTO)2]n (EMOF 4) (AFTO = 5-(4-amino-furazan-3-yl)-1-hydroxytetrazole) with high-dimensional structure were synthesized using hydrothermal and self-assembly methods in ethanol, respectively. Structural and performance tests show that EMOF 3 and 4 exhibit remarkable thermal stability and low mechanical sensitivity. This method is a simple, effective, and green technique for synthesizing high-dimensional EMOFs with high stability through self-assembly in ethanol solution. In addition, EMOF 3 and 4 can be used as primary green laser explosives.

Simple Method for Predicting the Heats of Formation of Energetic Metal–Organic Frameworks

Abstract The heats of formation (HOF) of energetic materials is crucial in determining their performance. A novel approach has been introduced to accurately predict the condensed phase HOF of energetic metal-organic frameworks (EMOFs). The experimental condensed phase HOF data of 63 EMOFs were utilized to develop and evaluate the model. This model relies on particular chemical bonds, elemental composition, and some of the specific structural parameters that can be obtained from the chemical structures of EMOFs. This model can be easily applied to EMOFs with intricate compositions and structures, without the need for complicated computer codes. Statistical parameters along with the internal and external validation approaches were employed to assess the accuracy, precision, goodness-of-fit, and goodness-of-prediction of the model. Values of the coefficients of determination in training set, as well as internal and external validation, i.e., R2, $${\text{Q}}_{{{\text{LOO}}}}^{2}$$, $${\text{Q}}_{{5{\text{-fold}}}}^{2}$$, and $$R_{{{\text{External}}}}^{2}$$ are 0.96, 0.93, 0.91, and 0.94, respectively.

Highly Dense N-N-Bridged Dinitramino Bistriazole-Based 3D Metal-Organic Frameworks with Balanced Outstanding Energetic Performance.

Due to the inherent conflict between energy and safety, the construction of energetic materials or energetic metal-organic frameworks (E-MOFs) with balanced thermal stability, sensitivity, and high detonation performance is challenging for chemists worldwide. In this regard, in recent times self-assembly of energetic ligands (high nitrogen- and oxygen-containing small molecules) with alkali metals were probed as a promising strategy to build high-energy materials with excellent density, insensitivity, stability, and detonation performance. Herein, based on the nitrogen-rich N,N'-([4,4'-bi(1,2,4-triazole)]-3,3'-dial)dinitramide (H2BDNBT) energetic ligand, two new environmentally benign E-MOFs including potassium [K2BDNBT]n (K-MOF) and sodium [Na2BDNBT]n (Na-MOF) have been introduced and characterized by NMR, IR, TGA-DSC, ICP-MS, PXRD, elemental analyses, and SCXRD. Interestingly, Na-MOF and K-MOF demonstrate solvent-free 3D dense frameworks having crystal densities of 2.16 and 2.14 g cm-3, respectively. Both the E-MOFs show high detonation velocity (VOD) of 8557-9724 m/s, detonation pressure (DP) of 30.41-36.97 GPa, positive heat of formation of 122.52-242.25 kJ mol-1, and insensitivity to mechanical stimuli such as impact and friction (IS = 30-40 J, FS > 360 N). Among them, Na-MOF has a detonation velocity (9724 m/s) superior to that of conventional explosives. Additionally, both the E-MOFs are highly heat-resistant, having higher decomposition (319 °C for K-MOF and 293 °C for Na-MOF) than the traditional explosives RDX (210 °C), HMX (279 °C), and CL-20 (221 °C). This stability is ascribed to the extensive structure and strong covalent interactions between BDNBT2- and K(I)/Na(I) ions. To the best of our knowledge, for the first time, we report dinitramino-based E-MOFs as highly stable secondary explosives, and Na-MOF may serve as a promising next-generation high-energy-density material for the replacement of presently used secondary thermally stable energetic materials such as RDX, HNS, HMX, and CL-20.

Two Energetic Framework Materials Based on DNM-TNBI as Host Molecule: Effectively Coordinated by Different Cations.

With the demand of develop outstanding-performance energetic materials, 1-(dinitromethyl)-4,4',5,5'-tetranitro-1H,1'H-2,2'-biimidazole (DNM-TNBI) emerged as a great contender (D: 9102 m ⋅ s-1; P: 37.6 GPa). However, the relatively poor thermal stability (Td: 142 °C) limits its practical application. In this study, DNM-TNBI as a host molecule to synthesize two new energetic open-framework materials by effectively coordinated with different cations. Their supramolecular structures were investigated and indicated that [DNM-TNBI2 -][2NH4 +] and [DNM-TNBI2 -][2K+] can be classified as a new energetic hydrogen-bonded ammonium framework (EHAF) and an energetic metal organic framework (EMOF). Meanwhile, their thermal stabilities are higher than that of DNM-TNBI and have satisfactory detonation performance ([DNM-TNBI2 -][2NH4 +], D: 8050 m ⋅ s-1, P: 26.4 GPa; [DNM-TNBI2 -][2K+], D: 8301 m ⋅ s-1, P: 30.8 GPa).

Construction of energetic metal-organic frameworks based on 5-aminotetrazole

Metal-Organic Frameworks (MOFs) have recently gained prominence as a novel class of energetic materials, owing to their systematic design and the ability to fine-tune properties such as energy content, sensitivity, and thermal stability. In this study, two new MOFs namely Cd(5-AT)3NH2(CH3)2+(1) and Zn(5-AT)(AMP) (2) (5-HAT = 5-aminotetrazole) were prepared under solvothermal conditions using 5-aminotetrazole as the high-nitrogen energetic ligand. X-ray single crystal diffraction analysis revealed that compound 1 possess an ABX3-type perovskite-like structure, whereas compound 2 forms a two-dimensional layer. The high thermal stability of both compounds were confirmed through thermogravimetry (TG) and differential scanning calorimetry (DSC). Their constant-volume combustion heat (ΔcU) was first determined by oxygen-bomb calorimetry and then the standard molar enthalpy of formation (ΔfHo) was calculated. Furthermore, both compounds demonstrated great detonation properties and low sensitivity, showing their potential application as new explosive materials (EMs).

Application and prospects of EMOFs in the fields of explosives and propellants.

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.

A novel and reliable method for prediction of the density of energetic metal–organic frameworks

A novel and reliable method for prediction of the density of energetic metal–organic frameworks

An aldehyde-group-containing energetic ZIF with unprecedented “negative” catalytic properties for seven different energetic materials

Energetic materials possessing high energy content, exceptional heat resistance, and insensitivity have long been recognized as a significant and prominent subject of academic debate. In this study, the necessity for high-energy explosives in both military and civilian domains prompted the introduction of the concept of an “energetic negative-burning rate catalyst” in heat-resistant and insensitive energetic materials. Therefore, a typical and effective catalyst (ZIF-90) was discovered. ZIF-90, which can be easily synthesized and features a large specific surface area and regular pore structure, contributes to molecular-scale changes in the pyrolysis process of energetic materials. Additionally, the presence of surface aldehyde groups facilitates the partial absorption of heat, thereby collectively contributing to the augmentation of pyrolysis peak temperatures for seven distinct energetic materials (RDX, HMX, CL-20, LLM-105, LLM-126, AlH3, and DAP-4). Specifically, the pyrolysis peak temperatures were elevated by 6.6 ​°C, 1.7 ​°C, 1.6 ​°C, 6.4 ​°C, 1.4 ​°C, 13.1 ​°C, and 7.0 ​°C, respectively. Moreover, the highly stable ZIF-90, functioning as an intrinsically insensitive Energetic Metal-Organic Framework (EMOF), not only effectively mitigates the sensitivity of energetic materials but also ensures minimal energy loss. Notably, the incorporation of a mere 5 ​wt% of ZIF-90 resulted in a significant enhancement of over one-fold in the heat resistance of LLM-105-based explosive cylinders, thereby validating the practical applicability of ZIF-90 in energetic materials. Moreover, the efficacy of ZIF-90 in solid propellant formulations was corroborated through flame experiments conducted on solid propellants. The development of such a pragmatic and universally applicable energetic negative-burning rate catalyst presents a promising strategy for the future advancement of high-performance, heat-resistant, and insensitive energetic materials.

Energetic metal-organic framework based on multinuclear clusters of Cu(II) and Fe(III) and its catalytic action on thermal decomposition of solid propellant components (RDX, HMX, CL-20 and AP)

Using nitrogen-rich tetrazole derivatives with multifunctional groups and ligand sites in metal–organic frameworks (MOFs) is a strategy to enhance their energy levels and broaden their applications. In the present study, a Cu(II) and Fe(III) heteronuclear {[CuFe3O(tza)6(H2O)3]·(NO3)2·OH}n (CuFe-MOF) based on the high-energy ligand tetrazole-1-acetic acid (Htza) was synthesized and its structures and properties were evaluated. The effects of CuFe-MOF as a catalyst on the thermal decomposition performance of the solid propellant components (RDX, HMX, CL-20 and AP) were investigated. The results demonstrated that the successfully prepared compound, an infinite 3D meshwork structure composed of [Fe3O(tza)6]+ and Cu2+, is in the ortho-hexagonal crystal system, P63/m space group. CuFe-MOF exhibited good thermal stability (Tdec = 238.9 °C) and insensitivity to impact (IS > 40 J) and friction (FS > 360 J). The addition of 5 % CuFe-MOF significantly reduces the decomposition peak temperature (1.9 °C, 5.8 °C, 5.7 °C and 71.4 °C) and apparent activation energy (38.5 kJ·mol−1, 38.3 kJ·mol−1, 63.9 kJ·mol−1, and 27.0 kJ·mol−1) of the RDX, HMX, CL-20, and AP compared to the raw materials while notably enhancing the heat release (509.8 J·g−1, 613.1 J·g−1, 578.4 J·g−1 and 584.3 J·g−1). Furthermore, good compatibility with RDX, HMX, CL-20, and AP was demonstrated using VST method. This research indicates the potential of {[CuFe3O(tza)6(H2O)3]·(NO3)2·OH}n as a promising alternative to the existing inert catalysts in propellants containing RDX, HMX, CL-20, and AP components, serving as an energetic combustion catalyst.

Fabrication of Energetic Metal-Organic Frameworks: Potassium 5-Carboxylato-3,4-Dinitropyrazole and Potassium 5-(Hydrazinecarbonyl)-3,4-Dinitropyrazole.

Energetic materials have been widely applied in civil and military fields, whose thermostability is a key indicator to evaluate their safety levels under severe conditions. Herein, two novel energetic metal-organic frameworks (EMOFs), namely, 4 and 6, were experimentally obtained and comprehensively characterized. The two EMOFs both possess unique three-dimensional (3D) coordination structures. With a high crystal density of 2.184 g·cm-3, EMOF 4 exhibits outstandingly superior thermostability (onset: 290 °C; peak: 303 °C), while EMOF 6 features onset and peak decomposition temperatures of 220 and 230 °C. The calculated energetic parameters of 4 and 6 are as follows: detonation velocity: 8731 m·s-1 and 8294 m·s-1; detonation pressure: 26.5 and 26.4 GPa. Compared to EMOF 6, EMOF 4 features high energy, excellent thermostability, and low mechanical sensitivities, which should be partly attributed to more plentiful coordination interactions. More coordination bonds are conducive to strengthening the EMOF framework, which needs much more energy to collapse, thereby maintaining higher thermal stability. The above favorable characteristics not only indicate EMOF 4 has a promising future in applications as a thermostable explosive but also provide an effective and feasible strategy for developing novel heat-resistant energetic materials via reinforced frame structures of EMOFs.

Nickel hydrazine nitrate/TNT hybrid: toward novel castable energetic nanocomposite with customized performance and decomposition kinetics via novel synergistic effect

Advanced energetic metal–organic frameworks (MOFs) can expose novel characteristics. Highly crystalline nickel hydrazine nitrate (NHN) MOF of 50 nm size was developed via wet coordination. NHN experienced superior decomposition enthalpy of 3100 J g−1 at 222 °C using differential scanning calorimetry. NHN could act as a sensitizer for trinitrotoluene (TNT) and could boost its decomposition enthalpy, detonation velocity, and decomposition kinetics. NHN nanoparticles were effectively integrated into TNT energetic matrix; proper particle dispersion was verified via energy-dispersive X-ray analysis, whereas TNT experienced decomposition enthalpy of 340 J g−1; NHN boosted TNT decomposition enthalpy by 282%, with decrease in main decomposition temperature by 31 °C. NHN/TNT nanocomposite revealed a decrease in TNT activation energy by − 23.5% and − 22% via Kissinger and KAS models, respectively. The synergistic effect of NHN on TNT was ascribed its high decomposition enthalpy, gaseous products. NHN could secure novel catalytic effect on TNT decomposition with increase in detonation velocity by 11%; this was ascribed to the release of active hydrogen that could support CH-α attack with the exclusive formation of nickel nanocatalyst.

Bespoke Energetic Zeolite Imidazolate Frameworks-8 (ZIF-8)/Ammonium Perchlorate Nanocomposite: A Novel Reactive Catalyzed High Energy Dense Material with Superior Decomposition Kinetics

Aluminum is the universal fuel for solid propellants; however, its passive oxide layer could impede the full exploitation of its enthalpy. Meanwhile, common catalyst could not contribute to combustion enthalpy. This study shaded light on the multifunctional energetic metal-organic frameworks ZIF-8 with combustion enthalpy 21 KJ/g as high energy dense material as well as a novel catalyst for solid propellants. As-prepared ZIF-8 particles exhibited a highly crystalline structure with an average particle size of 40 nm. The performance of ZIF-8 as high-energy dense material was assessed to aluminum particles via integration into ammonium perchlorate (APC). ZIF-8/APC and Al/APC composites were prepared via the solvent–nonsolvent method; the decomposition enthalpy was investigated via DSC. ZIF-8 offered an increase in APC total decomposition enthalpy by 98.4%, to 39.11% for Al. ZIF-8 exhibited a superior catalytic behavior by lowering the APC high-temperature decomposition peak (HTD) by 81.48 °C compared to 70.3 °C for Al. The decomposition kinetics of ZIF-8/AP nanocomposite was investigated via Kissinger’s formula. The ZIF-8 offered a remarkable reduction in APC apparent activation energy at low-temperature decomposition peak and HTD peaks by peak by 16.5% and 30%, respectively. The superior catalytic performance of ZIF-8 was attributed to Zn+2 electron deficient centers with the exclusive formation of ZnO nanoparticles during combustion. ZIF-8 with gaseous decomposition products could boost specific impulses.

An energetic MOF-assistant confined expansion strategy to fabricate Fe-doped porous carbon beads for advanced oxidation processes: Interfacial reaction mechanism and biological toxicity

Porous carbon material catalysts derived from MOFs-based precursors are gradually being used extensively in advanced oxidation possesses. However, some of the existing problems such as hard to recovery and easy to secondary pollution still need to be solved. Here, a series of Fe-doped energetic metal–organic framework (EMOF)-derived porous carbon spheres (EMFexS) were obtained by the phase inversion route. EMOFs puffed up during pyrolysis at high temperatures to create large-sized hierarchically porous structure. The large specific surface area (483.4 m2/g) and high nitrogen content, and hierarchically porous structure endow EMFe0.2S with excellent catalytic performance to remove tetracycline removal efficiency. By activating peroxymonosulfate (PMS), it was found that the rate constant (k) in EMFe0.2S/PMS system was 0.058 min−1, which was 1.75, 1.56 and 1.52 times than that of EMFe0S/PMS system, EMFe0.1S/PMS system and EMFe0.25S/PMS system, respectively. Experiments and material characterization point that the existence of nitrogen and iron in the catalyst were the potential active sites. The continuous flow catalytic reaction and biological toxicity experiments were employed to evaluate practical application value. This study provides new insights into the preparation of microspheres for water treatment with the help of EMOF-assisted confined expansion strategy.

Energetic metal-organic frameworks based on H2BTA and their effect on thermal decomposition of ammonium perchlorate

The effective thermal decomposition of ammonium perchlorate (AP) is an essential area of research in improving propellant combustion behavior. In this article, non-heavy metal cations such as Co(II), Mn(II), and Cu(II) were used for the preparation of a metal-organic framework based on 5,5′-tetrazole-amine (BTA). The low sensitivity of these compounds is of great importance in energy applications. XRD and FT-IR analyses were used to confirm the MOF structure. Adding MOF alters thermal decomposition processes, according to a thermal analysis obtained from the polymer DSC curve. The strong catalytic activity of the H-MOF for AP thermal decomposition is probably due to the synergistic effect of metal nodes and energetic ligands. The total heat released in the thermal decomposition of AP increased from 535.9 to 2435 J·g−1, and the high-temperature decomposition peak was dramatically reduced by 67 °C. Finally, we performed kinetic and thermodynamic studies on the thermal decomposition of AP and calculated the activation energy of AP decreased from 91.9 to 72.1 kJ·mol−1 and other parameters.

An ultrasensitive dietary caffeic acid electrochemical sensor based on Pd-Ru bimetal catalyst doped nano sponge-like carbon

Caffeic acid (CA) is widely present in the human daily diet, and a reliable CA detection method is beneficial to food safety. Herein, we constructed a CA electrochemical sensor employing a glassy carbon electrode (GCE) which was modified by the bimetallic Pd-Ru nanoparticles decorated N-doped spongy porous carbon obtained by pyrolysis of the energetic metal–organic framework (MET). The high-energy bond N-NN in MET explodes to form N-doped sponge-like carbon materials (N-SCs) with porous structures, boosting the adsorptive capacity for CA. The addition of Pd-Ru bimetal improves the electrochemical sensitivity. The linear range of the PdRu/N-SCs/GCE sensor is 1 nM-100 nM and 100 nM-15 μM, with a low detection limit (LOD) of 0.19 nM. It has a high sensitivity (55 μA/μM) and repeatability. The PdRu/N-SCs/GCE sensor has been used to detect CA in actual samples of red wine, strawberries, and blueberries, providing a novel approach for CA detection in food analysis.

Thermally stable and insensitive energetic metal-organic frameworks based on two new tetrazole ligands

Two new tetrazole ligands were designed and synthesized using simple methods in this study, namely 1H-tetrazole-5-carbohydrazide (HCHT, 1) and 2-amino-5-(1H-tetrazol-5-yl)-1,3,4-oxadiazole (HAOT, 2). Their solvent-free potassium salts [K(CHT)]n (3) and [K(AOT)]n (4) are new two-dimensional energetic metal-organic frameworks (EMOFs), and their structures were characterized using nuclear magnetic resonance (NMR), infrared spectroscopy (IR), mass spectrometry (MS), elemental analysis (EA), and single-crystal X-ray diffraction (SXRD). Both compounds 3 and 4 exhibit high decomposition temperatures (Td) of 314 ​°C and 310 ​°C, respectively and are highly insensitive to impact and friction stimuli (IS ​> ​40 ​J, FS ​> ​360 ​N). The detonation velocity and pressure of 3 were calculated at 9141 ​m ​s−1 and 29.0 ​GPa, respectively, and those of 4 were determined at 8423 ​m ​s−1 and 24.5 ​GPa, respectively. Furthermore, intermolecular interactions in 3 and 4 were analyzed using 2D fingerprint plots with associated Hirshfeld surfaces. In this manner, two thermally stable and insensitive EMOFs were developed based on two new tetrazole ligands.

Poly Tetrazole Containing Thermally Stable and Insensitive Alkali Metal-Based 3D Energetic Metal-Organic Frameworks.

Poly tetrazole-containing thermally stable and insensitive alkali metal-based 3D energetic metal-organic frameworks (EMOFs) are promising high energy density materials to balance the sensitivity, stability, and detonation performance of explosives in defense, space, and civilian applications. Herein, the self-assembly of L3- ligand with alkali metals Na(I) and K(I) was prepared at ambient conditions, introducing two new EMOFs, [Na3(L)3(H2O)6]n (1) and [K3(L)3(H2O)3]n (2). Single crystal analysis reveals that Na-MOF (1) exhibited a 3D wave-like supramolecular structure with significant hydrogen bonding among the layers, while K-MOF (2) also featured a 3D framework. Both EMOFs were thoroughly characterized by NMR, IR, PXRD, and TGA/DSC analyses. Compounds 1 and 2 show excellent thermal decomposition Td = 344 and 337 °C, respectively, compared to the presently used benchmark explosives RDX (210 °C), HMX (279 °C), and HNS (318 °C), which is attributed to structural reinforcement induced by extensive coordination. They also show remarkable detonation performance (VOD = 8500 m s-1, 7320 m s-1, DP = 26.74 GPa, 20 GPa for 1 and 2, respectively) and insensitivity toward impact and friction (IS ≥ 40 J, FS ≥ 360 N for 1; IS ≥ 40 J, FS ≥ 360 N for 2). Their excellent synthetic feasibility and energetic performance suggest that they are the perfect blend for the replacement of present benchmark explosives such as HNS, RDX, and HMX.

Accelerated thermal decomposition of ammonium perchlorate by electron transfer from dinuclear rare-earth EMOFs

Energetic metal-organic framework materials (EMOFs) are a class of energetic complexes formed by constructing energetic organic compounds with metal ions, which have garnered considerable attention due to their potential catalytic role in promoting the thermal decomposition of ammonium perchlorate (AP). However, how to improve the catalytic effect is still long-standing issue for EMOFs. Based on the electron transfer between rare earth metal ions with positive holes in the d, f-orbital and ammonium perchlorate ions, three rare earth EMOFs (La2(tza)3(H2O)6·4H2O, Ce2(tza)3(H2O)6·3H2O, and Nd2(tza)3(H2O)6·4H2O) were synthesized by solution evaporation method and their effects on the thermal decomposition of AP were investigated. The three EMOFs are binuclear isomorphic and form thermally stable (Tdet > 630.0 K) 3D structures through extensive hydrogen bonds. In addition, the introduction of lanthanide metals can enhance the electron transfer ability of EMOFs and promote the electron transfer of AP/EMOFs mixtures, which is beneficial to modulate the catalytic performance of EMOFs for the AP thermal decomposition. The addition of the three EMOFs caused the high-temperature decomposition peak of AP towards the low-temperature. Meanwhile, the temperature of the high-temperature decomposition peak was advanced by 46.8 K ∼ 59.8 K, and the activation energy (Ea) was reduced by 85.02 ∼ 117.71 kJ/mol, which could significantly improve the thermal decomposition performance of AP. Most importantly, compared to the other two EMOFs, the cation in Nd2(tza)3(H2O)6·4H2O has the highest effective nuclear charge number in the f orbital and strongest electron transfer ability, which can reduce the Ea of AP to 96.85 kJ/mol. Overall, the strategy of construction EMOFs by increase the electron transfer ability can provide guidance for the exploration of novel and efficient energetic catalysts.