Energetic Coordination Polymers Research Articles

Assembly of 1D Helical Energetic Coordination Polymers Using a Flexible Bridged Furazan-triazole Cation.

Two new energetic coordination compounds with 1D helical chain structures have been synthesized. First, the polyamine precursor 4,5-diamino-2-((4-amino-1,2,5-oxadiazole-3-yl)methyl)-2,4-dihydro-3H-1,2,4-triazole-3-imino chloride salt (TATAF-Cl) is obtained by incorporating 4-(chloromethyl)-1,2,5-oxadiazol-3-amine with 4H-1,2,4-triazole-3,4,5-triamine. Using a simple hydrothermal method, two energetic complexes, Ag(TATAF)(ClO4)2 (ECP-1) and Ag(TATAF)(NO3)2·H2O (ECP-2), with a helical 1D MOF structure of furazan and triazole were synthesized. Compounds ECP-1 and ECP-2 have relatively high nitrogen and oxygen content (N + O%: 52.04%, 61.04%), excellent crystal density (2.229 g cm-3, 2.116 g cm-3 at 298 K) and high heat of detonation (1.18 kcal g-1, 1.06 kcal g-1), good detonation performance (P: 35.34 GPa, 29.52 GPa; Dv: 8412 m s-1, 7794 m s-1), and moderate sensitivity (IS: 8 J, 13 J; FS: 72 N, 64 N). Structurally, the Ag+ of the two ECPs is coordinated with two energetic cations, two perchlorates, or one nitrate via tetragonal coordination to form a single helical structure that is interspersed up and down in two directions.

Constructing energetic coordination polymers through mixed-ligand strategy: way to achieve reduced sensitivity with significant energetic performance

This study explores the development of energetic coordination polymers (CPs) based on the atrz and HDNBA ligands through mixed-ligand strategy resulted in reduced sensitivity while maintaining the significant energetic performance.

Increasing the Energy Limit of Single Triazole–Tetrazole: HNANTT Modified with Its Energetic Coordination Polymers, Co-Crystals, and Energetic Salts

Increasing the Energy Limit of Single Triazole–Tetrazole: HNANTT Modified with Its Energetic Coordination Polymers, Co-Crystals, and Energetic Salts

The azido-embedded nanoarchitectonics of 2D energetic coordination polymer with high energy and low sensitivities

Recently, energetic coordination polymers (ECPs) have attracted much attention with the reinforced structure and enhanced energetic performance. In the fields of energetic materials (EMs), azido-based EMs always possess excellent detonation properties with high sensitivities. To develop novel EMs with high energy and low sensitivity simultaneously, in this study, a new azido-based ECP [Ni3(TTA)4(N3)2·2MeOH]n1 (HTTA ​= ​1H-tetrazol-1-ylacetic acid) featuring in a 2D network structure were obtained though nanoarchitectonics and a simple solvothermal method. The single crystal X-ray diffraction analysis indicates that 1 consists of Ni2+ centers and nitrogen-rich TTA– ligands with sensitive azido ions embedded in the 2D plane. Moreover, strong hydrogen bonds between carboxyl groups and MeOH molecules can further reinforce the structure and improve the stabilities. The decomposition temperature (Tdec), impact sensitivity (IS), and the friction sensitivity (FS) of 1 is 251 ​°C, >40 ​J, and 80 ​N, respectively, showing significant advantages in contrast with the reported azido-based ECPs. The calculated heat of detonation (ΔHdet) value is 3.270 ​kJ ​g−1, which is higher than that of TNT (ΔHdet ​= ​1.220 ​kJ ​g−1). According to the above analysis, compound 1 has promise to serve as EMs because of its high stability and excellent energetic performance.

Energetic Coordination Polymers Based on Copper Furazans and 1,2,3-Triazoles: Tuning the Oxygen Balance with Nitramino Functionalities

Four novel energetic complexes comprising furazan/nitramino groups were synthesized through a simple hydrothermal method. Owing to the introduction of an oxygen-containing nitramino group, Cu(DNAF)(NH3)3 (ECP-1), Cu(DNAF)(H2O)3 (ECP-2), Cu(ANFZ)2(H2O)5 (ECP-3), and Cu2(TA)2(H2O)6 (ECP-4) (DNAF = 4,5-dinitraminofurazan, ANFZ = 4-amino-3-nitraminofurazan, TA = 5-nitro-4-nitramino-1,2,3-triazole) possess relatively high oxygen contents and oxygen balance, indicating efficient energy release during the self-sustained redox process. In addition, these energetic coordination polymers (ECPs) possess exceptional crystal density and insensitivity to external stimuli. Compared to the energetic complexes reported previously, the oxygen balance and contents of nitrogen and oxygen atoms of ECP-1–ECP-4 remain at a relatively higher level (OB > −20%, N+O% > 60%), ECP-2 and ECP-4 have excellent positive oxygen balance (10.5% and 5.5%, respectively), and ECP-4 has the highest density (2.22 g/cm3) among these four coordination polymers.

Tailoring Transition Metals and Biuret into Laser-Ignitable Energetic Coordination Polymers with Improved Oxygen Balance and Multidentate Coordination Structures

Eight kinds of energetic coordination polymers (ECPs) with multi-coordination were designed and synthesized by combining the carbonyl group with coordination potential in biuret with transition metal nitrates and perchlorates (Co2+, Ni2+, Cu2+, and Ag+). The structures of these complexes are confirmed by infrared spectroscopy, elemental analysis, and X-ray single-crystal diffraction. The physical and chemical performance test results show that the solvent-free ECPs 7 (Cu(BIU)2(ClO4)2) has the best performance (Tdec = 328 °C, D = 7600 km·s–1, P = 27.8 Gpa, IS = 25 J, FS = 240 N). Among them, ECPs 7 and 8 (Ag(BIU)ClO4) have good detonation performance during hot plate and laser ignition tests (ECPs 7: P = 15 W, τ = 6 ms, E = 80 mJ; ECPs 8: P = 20 W, τ = 5 ms, E = 100 mJ). The result shows that improving the oxygen balance of ligands and constructing multidentate coordination structures may be a new effective strategy for improving the performance of laser-sensitive ECPs.

Graphene Oxide-Intercalated Tetrazole-Based Coordination Polymers: Thermally Stable Hybrid Energetic Crystals with Enhanced Photosensitivity

High-energy-density photosensitive pyrotechnics with good thermal stability have been in increasing demand in recent years. In this paper, graphene oxide (GO)-intercalated energetic coordination polymers (ECPs) are prepared with improved thermostability but great photosensitivity by using high nitrogen compounds azotetrazole (AT) and 5,5'-bistetrazole-1,1'-diolate dehydrate (BTO) as ligands. The decomposition activation energy (Ea) of Cu-AT has been increased from 135.7 to 151.9 kJ·mol-1 after intercalating 5 wt% GO, and in the meantime, the exothermic peak temperature (Tp) was increased by 12.6 °C. However, the decomposition Ea of Cu-BTO decreased under the effect of the same amount of GO with little effect on Tp. This confirms that GO has stabilization effects on the Cu-AT crystal, whereas the catalytic effects on Cu-BTO would dominate after dehydration with its crystal lattice collapse. Also, when the content of GO was 3%, the resultant GO0.03-Cu-AT exhibits a higher density (2.88 g·cm-3) and good thermostability (Tp = 293.7 °C). This ECP shows excellent low-energy laser ignition performance, which can be ignited with an energy of less than 1 mJ at a wavelength of 976 nm. Low-energy laser initiation is considered to be a safer but more reliable method than the traditional electrical-based ones.

Coordination polymerization of nitrogen-rich linkers and dicyanamide anions toward energetic coordination polymers with low sensitivities.

The design and synthesis of energetic materials (EMs) with high energy and reliable stabilities has attracted much attention in the field of EMs. In this work, we employed a strategy of the coordination polymerization of mild dicyanamide ions (DCA-), two isomeric ligands 1-methyl-5-aminotetrazole (1-MAT) and 2-methyl-5-aminotetrazole (2-MAT) to construct energetic coordination polymers (ECPs). Four new ECPs {[Co(DCA)2(1-MAT)2]·H2O}n1, [Cu(DCA)2(1-MAT)]n2, [Cd(DCA)2(1-MAT)2]n3 and [Cd(DCA)2(2-MAT)2]n4 were successfully synthesized through solvent evaporation routes. Compounds 1 and 4 display 1D chains, while 2 and 3 exhibit 2D-layered structures. Compounds 1-3 with the 1-MAT ligand all exhibit reliable thermal stabilities (> 200 °C). The calculated heats of detonation (ΔHdet) of 1-3 are all higher than 1.4 kJ g-1, which are higher than traditional explosive TNT (1.22 kJ g-1) and the reported ECP AgMtta (HMtta = 5-methyl-1H-tetrazole, ΔHdet = 1.32 kJ g-1). Furthermore, sensitivity testing demonstrates that 1-4 features low mechanical sensitivity to external mechanical action in contrast with the extremely sensitive azide-based ECPs [Cu3(2-MAT)2(N3)6]n. In addition, compound 2 shows hypergolic properties via an 'oxidizer-fuel' drop experiment, demonstrating its application prospects in the field of propellants. This work details an approach of synthesizing multipurpose ECPs with reliable stabilities by introducing mild dicyanamide anions into nitrogen-rich skeletons.

Synthesis of energetic coordination polymers based on 4-nitropyrazole by solid-melt crystallization in non-ionization condition

Based on the theory of crystallization, a solvent-free solid-liquid phase crystallization method called solid-melt crystallization was designed to prepare energetic coordination polymers. Two target compounds [Cu(NPyz)4NO3]·NO3 (ECPs-1) and Cu(NPyz)4(ClO4)2 (ECCs-2) were prepared through programmed heating and cooling by using 4-nitropyrazole (NPyz), (Cu(NO3)2·5H2O and Cu(ClO4)2·5H2O as raw materials. In addition, crystallization pre-experiments and annealing experiments also verified the feasibility of the method. Their structures were confirmed by IR, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction. The physicochemical properties and sensitivity test results showed that ECCs-2 has better thermal stability (Td = 221 °C), while ECPs-1 is less sensitive to mechanical stimuli (IS = 12 J, FS = 240 N). Calculations based on EXPLO5 and the Kamlet-Jacobs equation showed that ECCs-2 has more considerable detonation performance (P = 25.2 GPa, D = 7.5 km/s). In comparison, the more intuitive results from the HN test, flame test, thermal resistance test and lead plate explosion test revealed that ECCs-2 has an “ acceptable” detonation performance. The laser detonation test also showed that ECCs-2 is a promising excellent laser detonation material (E = 408 mJ, P = 24 W, τ = 17 ms).

Alkali metals dancing with 4,5-bis(1-hydroxytetrazol-5-yl)-2H-1,2,3-triazole: A family of energetic coordination polymers as prospective “green” pyrotechnics

Energetic coordination polymers (ECPs) with alkali metals remain at the forefront of pyrotechnics research due to their enormous potential for improving the safety and compatibility of pyrotechnics. Herein, we selected 4,5-bis(1-hydroxytetrazol-5-yl)-2H-1,2,3-triazole (H3OBTT) as the energetic linker because of its high nitrogen content (64.98%), abundant coordination sites, and good thermal stability (Tp = 246 °C). A family of new ECPs, namely, [Li2(HOBTT) (H2O)]n·2H2O (1), [Na2(HOBTT)(H2O)2]n·H2O (2), [K(H2OBTT)]n (3), and [Cs2(HOBTT)]n (4), were successfully prepared and characterized. Among them, 3 and 4 displayed three-dimensional solvent-free frameworks. They exhibit excellent thermal stabilities (Tdec>280 °C) and mechanical sensitivities (IS > 40 J, FS > 250 N). The flame colors of 1–4 were largely due to the unique excitation of different alkali metals ranging from red to yellow. The dynamic combustion of 1–4 discovered that the combustion duration of 3 was more than 1.720 s, and its flame stability time reached 1.400 s. Additionally, 3 was simple to prepare under mild conditions with a short reaction time, making it prospective “green” pyrotechnic candidates.

Controllable Structural Modulation: Assembling Variable Dimension Energetic Metal-Organic Frameworks via Free Protons.

Herein, we provide an efficient strategy for constructing three-dimensional (3D) energetic coordination polymers (ECPs), namely, metal-organic frameworks (EMOFs), avoiding solvent coordination without changing the organic ligands or metal nodes. Three ECPs with the same ligand and metal center, namely, two-dimensional (2D) layer ECP [Pb(HOBTT)(H2O)2]n (1), 3D solvent-free EMOFs [Pb(HOBTT)]n (2), and dense [Pb3(OBTT)2]n (3) (H3OBTT = 4,5-bis(1-hydroxytetrazol-5-yl)-2H-1,2,3-triazole), were rationally designed and synthesized via free protons. As expected, the theoretical density of 3 (4.080 g·cm-3) is greater than those of 2 (3.299 g·cm-3) and 1 (3.055 g·cm-3). Thermal stabilities indicate that their decomposition temperature exceeds 300 °C. Theoretical calculations show that the detonation performance of 3 is better than that of 1 and 2. The detonation performance of 1-3 was further proven by laser irradiation.

Two silver energetic coordination polymers based on a new N-amino-contained ligand: Towards good detonation performance and excellent laser-initiating ability

High-nitrogen heterocycle ligands, as an important part of energetic coordination polymers (ECPs), play a dominant role on regulating the energetic performance of ECPs. In inspire of the higher enthalpy and higher nitrogen contents after amination reaction, we synthesized a novel energetic ligand, 4-(2-amino-2H-tetrazol-5-yl)-1,2,5-oxadiazol-3-amine (ATNT), which has enhanced physicochemical properties (ΔHf: 524.2 kJ mol−1; D: 8248 m s−1; P: 24.67 GPa). Based on ATNT, two Ag-ECPs, [Ag2(ATNT)2](NO3)2 and [Ag2(ATNT)4](ClO4)2, were prepared and their structures were determined by single-crystal XRD. The high energetic performance of ATNT promotes the further improvement of the energy density of ECPs in this work. With excellent crystal densities (2.405/ 2.675 g cm−3) and high heat of detonation (0.91/ 0.88 kcal g−1), the detonation properties of two ECPs are 7286 m s−1/27.89 GPa, 8085 m s−1/40.08 GPa, respectively, which are at advanced level among the reported silver-based complexes. Moreover, laser initiation experiments show that both ECPs possess low initiation delay times (<20 μs) under 70 mJ initiation energy, revealing their potential as novel laser-initiating energetic materials. Presented ECPs in our work combine the advantages of simple synthesis method, high density, good detonation performance, excellent laser-initiating ability, exhibiting the great development potentials.

The role of anion in supramolecular aggregation and energetic properties in a series of Cd picolinamide complexes

A novel group of energetic compounds, known as energetic coordination polymers (ECPs), can be rationally designed by introducing of highly energetic ions like ClO4-, N3–, NO3– and NO2– into a polymeric framework. Herein we report the preparation of four novel cadmium(II) complexes with picolinamide (pia) as ligand and different ions: [Cd(pia)3](ClO4)2·2H2O (1), [Cd(NO3)(ac)(pia)2] (2), [Cd(NO2)2(pia)2] (3), [Cd2(μ1,1-N3)4(pia)2]n [Cd(μ1,1-N3)2(pia)]n (4). The presence of different anions from starting Cd(II) salts caused the formation of discrete coordination compounds(1, 2 and 3), and coordination polymer (4). In 2, 3 and 4 anions are coordinated to Cd(II), while in 1 perchlorate anions act as a counterion. The molecular and crystal structure analysis has shown that in all compounds pia acts as N,O-chelator in various coordination arrangements depending on the present anion (1, 2 and 4 - distorted octahedral, 3- distorted square antiprismatic). In the crystal structures, the dominant mode of intermolecular interaction is a strong head−to−head amide hydrogen bond, with exception of 1. Structural analysis of herein-reported compounds and previously described Cd(pia)A (A – anion) compounds has shown that bulky tetrahedral anions (ClO4- and SO42-) inhibit the formation of the strong head−to−head amide hydrogen bonds. The investigations of energetic properties and sensitivity indicate a possible application of compound 4 as a secondary explosive material with energetic properties like those of LA (lead azide), mercury fulminate, or ammonium nitrate.

Catalytic reactivity of graphene oxide stabilized Fe complexe of triaminoguanidine on thermolysis of HNTO/AN co-crystal

The catalytic activity of energetic coordination polymers of triaminoguanidine-transition iron, containing graphene oxide (GO-T-Fe-T) or not (T-Fe), on the thermolysis of an energetic co-crystal of hydrazinium 3-nitro-1,2,4-triazol-5-one and ammonium nitrate (HNTO/AN) has been investigated. DSC apparatus has been employed to investigate the thermal behavior of the different products. Four isoconversional integral kinetic approaches have been used to calculate the kinetics triplets. The achieved results showed that both of T-Fe and GO-T-Fe-T possess good catalytic activity. The decomposition temperature and the activation energy of the co-crystal were reduced by 31 kJ/mol and by 55 kJ/mol when T-Fe and GO-T-Fe-T are introduced, respectively. Furthermore, using iron as a metal in the catalysts increased the decomposition heat released from the co-crystal. This can be due to the better dispersion of Fe on the GO sheets, which enhanced the decomposition reaction.

High energy core-shell Al@PVDF/AP composites with enhanced combustion efficiency by doping of graphene-based carbohydrazide complexes as catalysts

In this paper, energetic combustion catalysts doped core–shell Al@PVDF/AP composites have been fabricated via a spray-drying method, where three kinds of graphene-based energetic coordination polymers (GECPs, GO-CHZ-Co, GO-CHZ-Ni and GO-CHZ-Cu) are employed. These composites have been characterized comprehensively in terms of morphologies, thermal decomposition behaviors, energy density, combustion performances and condensed combustion products (CCPs). The results show that the GO-CHZ-Co and GO-CHZ-Cu could increases the heat of explosion for Al@PVDF/AP composites from 6885.2 J·g−1 to 7491.0 J·g−1 and 7390.1 J·g−1, respectively, which are 8.8 % and 7.3 % higher than the blank reference samples. Moreover, the burn rates for these composites decrease when GO-CHZ-Co or GO-CHZ-Ni is included, indicating that these composites are promising candidates with improved energy density even unusually with decreased burn rates.

Multidimensional Energetic Coordination Polymers as Flame Colorants: Intriguing Architecture and Excellent Performance

A flexible and multifunctional 4-hydroxy-3,5-dinitropyrazole (DNPO) ligand was produced while seeking “green” energetic coordination polymers (ECPs). A series of alkali metal and alkaline earth metal ECPs of DNPO were successfully prepared and comprehensively characterized using elemental analysis, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. All ECPs were characterized via single-crystal X-ray diffraction. They have high crystal densities ranging from 1.743 (ECP-6) to 3.399 g cm–3 (ECP-5). Furthermore, various shapes of zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) supramolecular structures were found for the preparation of ECP, and each metal was combined in a specific and characteristic manner. All the prepared ECPs show excellent thermal stability, and the decomposition temperatures are higher than 347.0 °C (ECP-9) and 418.0 °C (ECP-1), due to the numerous coordination bonds and the network structure of the complex. The sensitivities toward impact and friction were tested using standard methods, and most of ECPs (ECP-1, ECP-2, and ECP-6 to ECP-9) can be considered insensitive to impact and friction, with values higher than 40 J and 360 N, respectively. ECP-3, ECP-4, and ECP-5 are sensitive toward impact (30, 12, and 8 J, respectively), while they are insensitive toward friction (≥360 N). Upon their combustion, these ECPs exhibit a series of unique flame colors, making them promising flame colorants for various ecofriendly pyrotechnic formulations.

Three new energetic coordination polymers based on nitrogen-rich heterocyclic ligand for thermal catalysis of ammonium perchlorate

Three new one-dimensional energetic coordination polymers (ECPs) were prepared by solvothermal method and liquid diffusion method, namely, [Mn(BODDTO)(H2O)4]n (1), [Zn(BODDTO)(H2O)4]n (2) and [Pb(BODDTO)(H2O)4]n (3) (H2BODDTO ​= ​5,5'-([3,3′-bi(1,2,4-oxadiazole)]-5,5′-diyl)bis(1H-tetrazol-1-ol)). Compounds 1 and 2 possess the same crystal structures, crystallizing in the triclinic space group P-1 with a calculated density of 1.970 ​g ​cm−3 for 1 and 2.047 ​g ​cm−3 for 2. Meanwhile, Compound 3 pertains to the P212121 space group of the orthorhombic crystal system with a density of 2.618 ​g ​cm−3. The thermal behaviors were studied by employing a Thermogravimetry instrument, the results show that the compounds have good thermal stability with the decomposition temperatures above 520 ​K. The studies of mechanical sensitivity and detonation performance reveal that these complexes are both safe and have high energy. Furthermore, the ability to catalyze the thermal decomposition of ammonium perchlorate (AP) by compounds 1–3 was studied through a differential thermal analysis instrument. The high-temperature decomposition peak temperature of AP is reduced by 94.8 ​K at most and the activation energy is also decreased. It is disclosed that three compounds can be potentially used as high-energy AP catalysts.

A Solvent‐free energetic coordination polymer [N, N‐(3,4‐dinitropyrazolate)Ag]: synthesis, structure and energetic performance

AbstractA novel solvent‐free energetic coordination polymer [Ag(3,4‐dnp)] was performed by dehydration. The structure was confirmed by single‐crystal X‐ray crystallography and the Ag(I) ions are coordinated in bidentate‐bridging mode. The results of thermal analysis (thermogravimetric and accelerating rate calorimeter) show that this compound has higher thermal stability than that of the traditional CHON‐containing energetic materials, RDX, HMX and CL‐20. The detonation velocity and detonation pressure of [Ag(3,4‐dnp)] are 5.532 km s−1, 15.88 GPa, respectively, which is lower than that HMX, RDX and TNT, and comparable with the 2D MOFs [Ag(Mtta)] based on the Ag ions and 5‐methyl tetrazole. The impact and friction sensitivities of this compound are infinitely close to RDX, state‐of‐the‐art explosive. The coordination polymers based on metal ions and nitropyrazole are promising potential as energetic materials.

Copper-Based Energetic Coordination Polymers Regulated by CN– and NO3– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri(1H-1,2,4-triazol-1-yl)benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu(TTB)(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field.

An Energetic Coordination Polymer with High Thermal Stability and Initiation Power

AbstractLead‐free, eco‐friendly primary explosive which can replace lead azide (LA) has been a long‐lasting challenge. Hereby, a new candidate copper(I) 5‐(2,2‐diamino‐1‐nitrovinyl)tetrazolate (CTX) was synthesized through a mild metathesis reaction by bridging nitrogen‐rich heterocycles with Cu(I) centers. The structure was characterized with IR spectrum, NMR spectrum, X‐ray diffraction, and elemental analysis. The linear reinforced structure and condensed packing pattern of CTX lead to its high density (2.16 g cm−3) and low sensitivities (IS=10 J, FS&gt;120 N). It also exhibits a remarkably high thermal stability (340 °C), which to our knowledge, is the highest one known for the energetic coordination polymers (ECPs). The initiation capability test reveals CTX has high priming ability comparable to LA. The combined properties and performances contribute to its future prospects as a promising green primary explosive.