Energetic Coordination Research Articles

Synthesis, crystal structure, and thermal properties of energetic complex Cu(II) and Ag(I) based on 3-amino-4-(4,5-diamino-1,2,4-triazole-3yl)-furazan

High nitrogen compounds have received much attention due to their great potential as high energy density materials, and the selection of high nitrogen heterocyclic rings as ligands for energetic coordination compounds (ECCs) play a leading role in regulating the energy properties of ECCs. Furazan is rarely used as a building block for the development of high-energy metal ligands. In this study, a new type of high nitrogen ligand 3-amino-4-(4,5-diamino-1,2,4-triazole-3yl)-furazan (ATF) was selected and four kinds of high energy coordination polymers [Cu(II)(ATF)2·4H2O](NO3)2·2H2O (1), [Cu(II)(ATF)2·4H2O](ClO4)2·2H2O (2), [Ag(I)(ATF)2]ClO4·H2O (3) and [Ag(I)(ATF)2NO3] (4) were prepared by water solvent volatilization method and characterized for the first time. The single crystal XRD confirmed that there were abundant hydrogen bond interactions in the four complexes, resulting in dense aggregation with densities of 1.680 ∼ 2.089 g·cm−3. Meanwhile, theoretical calculations show that the detonation velocities of the four ECCs, 7578 ∼ 8192 m·s−1. In terms of thermal stability, the decomposition temperatures of the four ECCs (Td: 253 ∼ 288 °C) showed higher thermal stability during the rapid heating process than the reported ECCs (Cu(PZCA)2(ClO4)2, [Ag+(daf)NO3−]n and CHHP). Both shock and friction sensitivities are greater than 20 J and 300 N. This new structural motif is a promising high-energy material. Moreover, they can promote the combustion decomposition of ammonium perchlorate (AP) well, and the promotion effect of 1 and 2 is better than that of 3 and 4. In the field of explosives and propellants, four ECCs can be attractive candidates.

Energetic Coordination Compounds: Investigation of Aliphatic Ligands and Development of Prototype Detonators.

In this work, energetic coordination compounds (ECCs) of transition metals (Fe, Ni, Cu, Zn) containing aliphatic amines as ligands were synthesized: ethylenediamine; 1,3-diaminopropane; tris(2-aminoethyl)amine; tris(3-aminopropyl)amine. The compounds were investigated in terms of ignition/explosion temperature, friction and impact sensitivity. For selected compounds, structural characterisation was presented (IR-ATR spectroscopy, Raman spectroscopy) and their morphology was determined (SEM, powder XRD). They were also investigated by differential scanning calorimetry (DSC). In order to assess the potential application of selected ECCs in detonators, underwater explosion tests were carried out, determining energetic performance. The results achieved for detonators containing ECCs were compared with those for reference detonators (containing pentaerythritol tetranitrate, PETN), indicating their potential use as a "green" alternative to nitric acid esters.

Unlocking the ultrafast laser response and low initiation energy of perchlorate-free tetrazine-based energetic coordination compounds

Laser ignition technology holds significant and diverse applications in the domains of weapon equipment, aerospace and engineering blasting because of its exceptional resistance to electromagnetic interference, outstanding ignition efficiency and flexible controllability. However, the commercial initiation material B/KNO3 still suffers the high minimum laser initiation energy (Emin = 723.2 mJ) and lengthy ignition delay time (ID=160 ms). In this study, we have successfully synthesized two perchlorate-free energetic coordination compounds (ECCs): [Cu(DHT)(NO3)(H2O)](NO3) 1 and [Ni(DHT)(H2O)2](NO3)22 (DHT=3,6-dihydrazine-1,2,4,5-tetrazine). Though two compounds with similar structures show high explosion parameter values, the behaviors of laser responsive ignition are different. Noteworthy, laser ignition tests demonstrate that Cu-based 1 exhibits excellent laser response characteristics with an ultra-low Emin value of 4.2 mJ and a short ID time of 20 ms, while Ni-based 2 shows extremely insensitivity to laser under identical conditions. Furthermore, theoretical calculations reveal that the higher sensitivity of 1 towards laser response activity might be attributed to the narrower band gap (Eg = 0.44 eV) resulting from Cu centers in contrast with 2. In addition, mechanical sensitivities between 1 and 2 are discussed sufficiently by theoretical and structural studies. Compared to the commercial B/KNO3, compound 1 has promise to serve as a competitive laser ignition material.

Energetic transition metal complexes based on 1‐allylimidazole and nitrocyanamide: Syntheses, characterizations and catalytic performances on the thermal decomposition of ammonium perchlorate

AbstractTo explore combustion catalysts for solid propellants, four novel energetic coordination compounds were prepared with the anion of nitrocyanamide (NCA) as the ligand and 1‐allyl‐imidazole (AIM) as the ligand, and transition metals Mn, Co, Ni, and Cu as the central ions. The structures of these compounds were [Mn(AIM)4] (NCA)2 (1), [Co(AIM)4](NCA)2 (2), [Ni(AIM)4](NCA)2 (3), [Cu(AIM)4](NCA)2 (4). The results showed that all of the compounds possessed high energy density, and compound 2 had a mass energy density (Eg) of 17.9 kJ g−1 and a volume energy density (Ev) of 25.59 kJ cm−3. The catalytic effect of these compounds on the thermal decomposition of ammonium perchlorate (AP) was studied using DSC. The addition of 5 % catalyst to AP samples advanced the high‐temperature decomposition temperature and significantly increased the heat release. Compound 4 exhibited the best catalytic performance, with an increased heat release of 1739 J g−1, decomposition temperature advanced by 88.2 °C, and activation energy reduced to 74.74 kJ mol−1. These results demonstrate the potential of these compounds as combustion catalysts for solid propellants.

High‐pressure studies of Mn2(C2H6N6)4(NO3)4·2H2O by Raman scattering, infrared absorption, and synchrotron X‐ray diffraction

AbstractMn2(C2H6N6)4(NO3)4·2H2O (Mn) as one of the energetic coordination complexes was chosen for high‐pressure research. In this work, Mn was analyzed by in situ Raman scattering, infrared absorption, and synchrotron angle‐dispersive X‐ray diffraction (ADXRD) technologies up to ~20 GPa at room temperature. The vibrational modes of Mn at ambient pressure were comprehensively resolved based on the experimental results. Detailed spectral analyses revealed that Mn underwent three pressure‐induced phase transitions at 0.5, 2.5, and 5.7 GPa, respectively. ADXRD experiments confirmed the existence of these three phase transitions in Raman and infrared spectra analyses. Based on the analysis of the vibrational spectra and the changes of lattice parameters under pressure, it can be considered that the deformation of the 3‐hydrazino‐4‐amino‐1, 2, 4‐triazole (HATr) ligand led to the first phase transition, and the distortion of the triazole ring induced the second phase transition, and the rearrangement of the hydrogen bonds resulted in the third phase transition. In addition, it can be inferred from Raman spectra and ADXRD data that Mn may have experienced the abnormal expansion during the first phase transition. This work may lay the foundation for further investigating the structure and properties of energetic coordination complexes under pressure.

1- and 2-Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds.

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by laser initiation in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)6](ClO4)2 were highlighted by the measurement of the temperature-dependent susceptibility curve.

N‐Azidoethyl azoles through N‐alkylation under highly harmonized reaction conditions: Synthesis, characterization, and complexation as energetic coordination compounds

AbstractOrganic azides are universally important in many areas of chemistry, particularly in organic synthesis. The availability of these azides often depends on specific transfer reagents and reaction conditions, or only work with certain substrates. Customizable transfer reagents offer a safe and direct pathway to desired compounds, thereby increasing the availability of N‐alkyl‐azides. In an effort to streamline the synthesis and broaden the scope of N‐azidoethyl‐containing molecules, three different versatile azidoethyl transfer reagents were synthesized and a uniform reaction protocol with azoles as substrates, including imidazole, pyrazole, 1,2,3‐triazole, 1,2,4‐triazole, and tetrazole was established. The resulting azidoethyl‐azoles were further used as ligands for energetic coordination compounds in an effort to create new lead‐free primary explosives. A comprehensive characterization of the transfer reagents, the azidoethyl‐containing products, and energetic coordination compounds was conducted using multinuclear nuclear magnetic resonance (NMR), elemental analysis, mass spectrometry, and infrared spectroscopy (IR). Furthermore, their thermal stability and sensitivity toward friction and impact were determined as well as the detonation properties were calculated by using the EXPLO5 code.

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.

Dinitromethyltetrazole (DNMT)-based energetic coordination polymers (ECPs) as lead-free primary explosives and laser initiators

A series of energetic coordination polymers has been synthesized by incorporating dinitromethyltetrazole with alkali metals (Na, K, Rb and Cs), which have potential applications in laser initiating high explosives.

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.

Synthesizing new Bi-structure energetic coordination compounds using ternary components

[Ag(1-APZ-5-HCA)(ClO4)2]n (ECPs-1) has a dual structure of ionic salt and coordination compounds. It also has the advantages of high ClO4− content and oxygen balance, acceptable mechanical stimulation and excellent explosion performance.

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.

Synthesis of energetic coordination compounds based on pyrazole and 4-chloropyrazole via co-melting crystallization method

Using pyrazole, 4-chloropyrazole, Cu(NO3)2, and Cu(ClO4)2 as raw materials, the target crystals of ECCs can be directly obtained by co-melting and heating, offering a more efficient alternative to traditional solvent-based preparation methods.

Elevating the energetic capabilities of metal coordination compounds by incorporating nitrate anions.

In the realm of energetic materials research, there has been notable interest in energetic coordination compounds (ECCs) owing to their remarkable thermal stability and resistance to mechanical stimuli. This study successfully demonstrated the synthesis of an azole-based C-C bonded ECC1 under ambient conditions. A comprehensive characterization study, employing techniques such as IR, TGA-DSC, NMR and single-crystal X-ray diffraction analysis, was conducted. The bulk compound was investigated by PXRD analysis. In-depth exploration of its physicochemical and energetic performance revealed good detonation properties such as a detonation velocity (VOD) of 8553 m s-1 and a detonation pressure (DP) of 36.2 GPa, which surpass those of heat resistant explosives HNS and TATB. Due to its remarkable high melting and onset decomposition temperature (278/379 °C), it also outperforms the benchmark explosive HMX (279 °C) and the heat-resistant explosive HNS (318 °C) and shows a high impact sensitivity (IS) of 20 J and friction sensitivity (FS) of 360 N. The study also employed Hirshfeld surface and 2D fingerprint analysis to elucidate the close contact of atoms within the molecules. The combination of high detonation properties, thermal stability, and low sensitivity makes the synthesized ECC1 intriguing for further investigations and suggests its potential applications as a safe and high-energy-dense material.

Preparation of Highly Energetic Coordination Compounds with Rich Oxidants and Lower Sensitivity Based on Methyl Groups.

Revamping the structure of energy storage is an efficient strategy for striking a balance between the performance and sensitivity of energetic materials to achieve high energy and reduced sensitivity. In continuation of prior research, this study utilized the ligand 3,5-dimethyl-1H-pyrazole-4-carbonhydrazide (DMPZCA) and innovatively designed and synthesized the compound ECCs [Cu(HDMPZCA)2(ClO4)2](ClO4)2·2H2O (ECCs-1·2H2O). Compared with the former research, solvent-free compound ECCs-1 refers to an innovative material characterized by a dual structure involving ionic salts and coordination compounds. Due to these unique structures, ECCs-1 exhibits an increased [ClO4-] content, a higher oxygen balance constant (OB = -7.9%), and improved mechanical sensitivity (IS = 8 J, FS = 32 N). Theoretical calculations support the superior detonation performance of ECCs-1. Additionally, experimental results confirm its ignition capability through lower-threshold lasers and highlight the outstanding initiation potential and explosive power, making it a suitable candidate for primary explosives.

Regulating the Coordination Environment by Using Isomeric Ligands: Enhancing the Energy and Sensitivity of Energetic Coordination Compounds.

Transforming the energy storage structure is an effective approach to achieve a balance between the detonation performance and the sensitivity of energetic compounds, with a goal of high energy and low sensitivity. Building upon previous work, this study employed an isomeric compound 1H-pyrazole-3-carbohydrazide (3-PZCA) as a ligand and creatively designed the energetic coordination compound (ECC) Ag(3-HPZCA)2(ClO4)3 (ECC-1). It is a novel material with a dual structure of ionic salts and coordination compounds, which represents the first report of such a structure in Ag(I)-based ECCs. With its unique structures, ECC-1 exhibits a larger [ClO4-] content, a higher oxygen balance constant (OB = 0%), and superior mechanical sensitivity (IS = 13 J and FS = 40 N). Theoretical calculations indicate that ECC-1 has a higher detonation performance compared to previous work. Furthermore, the explosive experiment testing results demonstrate that it can be ignited by lower-threshold lasers and possesses excellent initiation capability and explosive power, making it suitable not only as a primary explosive but also as a secondary explosive.

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

Study on Primary Explosive: Cu(ClO4)2-Based Energetic Coordination Compounds as a Template

Study on Primary Explosive: Cu(ClO₄)₂-Based Energetic Coordination Compounds as a Template

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.

Application of 1- and 2-propargyl-tetrazole in laser-ignitable energetic coordination compounds

1- and 2-Propargyl-tetrazole (1- and 2-PryTz) were synthesized by reaction of propargyl bromide with sodium tetrazolate and used as ligands in energetic coordination compounds (ECCs) and evaluated concerning their thermal and mechanical sensitivities. Furthermore, the two nitrogen-rich compounds 1-((1H-1,2,3-triazol-4-yl)methyl)-1H-tetrazole (TriMT, 3) and 1-((1-(2-(1H-tetrazol-1-yl)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-tetrazole (TriMTET, 4) were prepared. Both were characterized by IR spectroscopy, NMR measurements, and low-temperature X-Ray diffraction analysis. Due to the highly endothermic enthalpy of formation of the propargyl-tetrazole ligands, powerful, yet relatively safe to handle, laser-ignitable ECCs were obtained.