English

• As known, the performance of energetic materials exhibits inherently contradictory concerning both energy and safety^[1]. Over the past decades, the long-term challenge in this field has been to develop high-energy-density materials (HEDM) with low toxicity, acceptable sensitivity, excellent thermal stability, and excellent detonation performance^[2-4]. Energetic coordination polymers (ECPs), bridging metal ions and energetic organic ligands, are considered promising candidates to balance the conflicts. Specifically, the packed structures of ECPs with strong coordination bonds can significantly enhance the stability for practical applications. Meanwhile, powerful energetic organic molecules can directly ensure the energy source, and the designability of ECPs also facilitates the investigation of the relationship of structure-energy-sensitivity^[5-6]. Based on reported high-performance ECPs, introducing rich-nitrogen heterocycle ligands into a molecule is an effective and feasible strategy to improve performance. The significant reason is that rich-nitrogen heterocycles have abundant energetic C=N bonds (615 kJ·mol^-1) and N=N bonds (456 kJ·mol^-1) with the formation of high positive enthalpy^[7-9]. At the same time, abundant coordination sites on the heterocycles generally have various coordination modes, resulting in the forming of diverse energetic materials. Therefore, more exploration is expected to be conducted to develop such materials to improve detonation performance^[10-12].

  In our research, a rich-nitrogen ligand 4, 5-bis (tetrazol-5-yl)imidazole (H₃BTI) (w_N=68.61%) is considered to construct novel ECPs. One factor is that a high nitrogen content of ligand H₃BTI may contribute to the enhancement of energetic performance. Another factor is the coplanarity of the imidazole and tetrazole rings that could play a role in the construction of rigid structure ECPs^[13]. Recently, different from the previously synthesized Pb-based ECPs ([Pb(HBTI)]_n)^[14], our current attention is focused on low-toxicity ions to construct eco-friendly energetic materials that can replace toxic explosives. Well-known, the combustion performance of the high-efficiency oxidants ammonium perchlorate (AP) and 1, 3, 5-trinitro-1, 3, 5-triazacyclohexane (RDX) has a direct effect on solid propellant properties^[15]. However, traditional combustion promoters (metal powders, metal oxide, carbon nanotubes) lack energetic groups leading to partial energy loss during combustion. Recent studies have proven that ECPs are effective combustion promoters toward the AP and RDX in the propellant^[16-19]. During the combustion process, it can release massive heat and generate metal/metal oxide active centers, as well as the nitrogen-rich ligands further can provide a certain amount of energy^[20].

  Considering the above mentioned, a novel ECP [Co₄(HBTI)₄(H₂O)₈] (1) was synthesized based on the energetic ligand H₃BTI (Scheme 1) and low-toxicity cobalt ions in this work. The crystal structure of 1 and its composition and thermal stability were systematically identified by various characterization methods. Based on the two different methods of Kissinger and Ozawa-Doyle, the non-isothermal kinetic parameters of 1 were also determined. In addition, energetic properties for 1 were calculated and discussed in detail. The sensitivity experiment results show that 1 exhibits low sensitivity to impact and friction. Additionally, ECP 1 could promote the decomposition temperature of AP and RDX by about 25 and 11 ℃, respectively.

  Scheme 1

  

  Scheme 1.  Synthetic diagram of ligand H₃BTI

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  1.   Experimental

  1.1   Materials and measurements

  Solid reagents used included 4, 5-dicyanoimidazole, sodium azide, cobalt nitrate hexahydrate, ammonium perchlorate, and 1, 3, 5-trinitro-1, 3, 5-triazacyclohexane. Liquid reagents consisted of N, N-dimethylformamide, nitric acid, and hydrochloric acid. The 4, 5-dicyanoimidazole was purchased by Beijing J & K Scientific Technology Co., Ltd. The ammonium perchlorate and 1, 3, 5-trinitro-1, 3, 5-triazacyclohexane were provided by the Xi′an Modern Chemistry Research Institute. All other reagents were obtained from Aladdin Reagent Co., Ltd.

  The IR spectrum data were obtained using Bruker Tensor 27 infrared spectrometer, employing the KBr pellet method in a wavelength range of 4 000-400 cm^-1. Elemental analysis was performed using a Vario EL Ⅲ analyzer. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were performed using the Netzsch STA 449C instrument and CDR-4P thermal analyzer, respectively. Crystal morphology was observed using Carl Zeiss Microscopy GmbH microscope. Impact sensitivity (IS) was characterized using a fall hammer instrument by the standard staircase method. Friction sensitivity (FS) was measured using the BAM method.

  1.2   Synthesis

  1.2.1   Synthesis of ligand H₃IBT

  The ligand H₃IBT was prepared by an optimized reported method^[21]. At room temperature, NaN₃ (0.048 mmol, 3.120 g), NH₄Cl (0.047 7 mmol, 2.557 g), 4, 5-dicyanoimidazole (0.02 mol, 2.362 g) were added into a round-bottom flask with N, N-dimethylformamide (30 mL) and stirred. The solution was refluxed and gradually heated to 95 ℃. After 8 h, the solid was collected by vacuum filtration, and it was dispersed in deionized water (200 mL) with 10% hydrochloric acid. Then, the solid was further dispersed in NaOH aqueous solution. 10% hydrochloric acid was added until the generation of a white solid. After washing, filtering, and drying, the ligand H₃IBT was obtained (Yield: 95.2%).

  1.2.2   Synthesis of ECP 1

  Co(NO₃)₂·6(H₂O) (0.2 mmol, 0.047 4 g) and the energetic ligand H₃BTI (0.05 mmol, 0.0102 g) were sealed into a 25 mL autoclave with deionized water (6 mL). At room temperature, the nitric acid (34 µL) was subsequently dripped into the autoclave and stirred. Then the autoclave was subsequently heated until 150 ℃ and maintained for three days. The cooling rate was 3 ℃·min^-1. After filtration, washed in distilled water, the pink single crystals were obtained (Yield: 58%). Elemental analysis Calcd. for Co₄C₂₀H₂₄O₈N₄₀(%): C 20.19, H 2.02, N 47.12; Found(%): C 20.22, H 2.06, N 47.16. IR (KBr, cm^-1): 3 428(s), 3 131(s), 2 861(s), 2 680(w), 2 361(w), 1 611(s), 1 568(s), 1 487(m), 1 243(w), 1 037(w), 983(m), 880(m), 851(m), 700(w).

  1.3   X-ray crystallographic analysis

  The pink block single crystal of 1 was selected for the X-ray diffraction analysis. The crystal data of 1 was determined by the Bruker Apex Ⅱ CCD X-ray diffractometer with graphite-monochromated Mo Kα radiation using φ‑ω scan technique. The wavelength was 0.071 073 nm. Using the SHELXS-97 program, the crystal structure of ECP 1 was solved by the direct methods and further refined by full-matrix least squares on F² with the Olex2 program. All the hydrogen atoms were placed geometrically and refined by a riding model. Table 1 lists the related crystallographic parameters, and some bond information for 1 is also provided in Table S1 (Supporting information).

  Table 1

  

  Table 1.  Structure refinements and crystalline information of ECP 1

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  Parameter	1
  Formula	C20H24Co4N40O8
  Formula weight	1 188.51
  Crystal system	Monoclinic
  Space group	P21/n
  a / nm	7.501(6)
  b / nm	16.013(12)
  c / nm	16.186(12)
  β / (°)	102.517(14)
  V / nm3	1 898(2)
  Z	2
  Dc / (g·cm-3)	2.08
  μ / mm-1	1.826
  F(000)	1 192
  GOF on F2	1.023
  R1, wR2 [I > 2σ(I)]	0.081 1, 0.209 9
  R1, wR2 (all data)	0.124 4, 0.234 3

  2.   Results and discussion

  2.1   Crystal structure of ECP 1

  According to the result of single crystal measurement, ECP 1 crystallizes in the monoclinic system with the P2₁/n space group. The asymmetric unit of 1 is made up of two Co(Ⅱ) ions, two HBTI^2- ligands, and four H₂O molecules. The Co(Ⅱ) ions in 1 have two different coordination modes, Both Co1 and Co2 adopt octahedral coordination geometry, which contains two oxygen atoms and four nitrogen atoms from H₂O molecules and HBTI^2- ligands. The difference lies in that on the equatorial plane, the O1 atom in Co1 replaces the N3 atom in Co2, and at the bottom of the octahedron, the N18A atom replaces the O3 atom (Fig. 1). Co(Ⅱ) ions in 1 are bridged by the HBTI^2- ligand, forming the [Co1-(μ₂′-HBTI)-Co2-(μ₂′-HBTI)-Co1] configuration with a μ₂∶η¹∶η¹∶η¹∶η¹ coordination mode. In ECP 1, the shortest distance of Co…Co is 0.620 8 nm, and the distances of Co—N range from 0.211 5(9) to 0.214 9(10) nm, The dinuclear units are connected with the μ₂-HBTI^2- ligands (Fig. 2), generating a symmetrical ellipsoidal tetranuclear structure. Under high temperature and acidic conditions, one of the tetrazole rings in 1 has slight torsion, whereas another tetrazole ring in its deprotonated form participates in coordination^[22]. The special structural characteristics are different from those reported ones with the coplanarity of H₃BTI. Moreover, the molecule contains a lot of hydrogen bonds, which bring about the formation of the 3D supramolecular structure for 1 (Fig. 3).

  Figure 1

  

  Figure 1.  Coordination polyhedron for Co ions in ECP 1

  Symmetry code: A: 2-x, 1-y, -z.

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  Figure 2

  

  Figure 2.  Ellipsoidal diagram of molecular structure of ECP 1

  The ellipsoid contour has 50% probability levels in the structure; Symmetry code: A: 2-x, 1-y, -z.

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  Figure 3

  

  Figure 3.  Three-dimensional supramolecular configuration of ECP 1 along the b-axis

  Symmetry codes: B: 1-x, 1-y, -z; C: -1+x, y, z; D: -1/2+x, 1/2-y, 1/2+z.

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  2.2   Thermal decomposition behavior

  The energetic materials must balance the detonation performance and safety parameters to ensure safety during experimental or operational processes^[23-24]. Thus, for evaluating the thermal stability of ECP 1, under a nitrogen atmosphere, the TG and DSC experiments with a heating rate of 10 ℃·min^-1 up to 800 ℃ for single crystal sample 1 were performed. According to the TG curve, the thermal decomposition of 1 went through two weight loss processes (Fig. 4). The first process took place at temperatures ranging from 230 to 270 ℃ with a 12.98% weight loss (Calcd. 12.16%) as a result of the loss of coordinated water molecules. In addition, the abundance of hydrogen bonding in the system causes a deceleration of the weight loss process. After this, a steady state remained until 337 ℃. Then, the second weight loss process happened owing to the main framework collapse of 1, and the mass fraction of the residue was 52.66%. Besides, the DSC curve for 1 showed an endothermic stage before transitioning into exothermic periods with peak temperatures of 368 ℃(Fig. 5).

  Figure 4

  

  Figure 4.  TG curve of ECP 1

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  Figure 5

  

  Figure 5.  DSC curve of ECP 1

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  2.3   Non-isothermal kinetics analysis

  We utilized two different methods including Kissinger and Ozawa-Doyle to study non-isothermal kinetic for ECP 1. As follows, the calculation formulas 1 and 2 represent Kissinger and Ozawa-Doyle methods^[25-26], respectively:

  $ \ln \frac{\beta}{T_{\mathrm{p}}^2}=\ln \frac{A R}{E}-\frac{E}{E T_{\mathrm{p}}} $

  (1)

  $ {\rm{lg}}\beta + \frac{{0.456{\rm{}}7E}}{{E{T_{\rm{p}}}}} = C $

  (2)

  where E and β are apparent activation energy and linear heating rate, respectively; A and C are the pre-exponential factor and a constant, respectively; while R and T_p are gas constant and the peak temperature. DSC technology was performed to measure the first exothermic peak temperature (T_p) of 1 at varied heating rates (2, 5, 8, and 10 ℃·min^-1). Based on the experiment results, the apparent activation energy (E_k, E_o), pre-exponential factor (A_k), and linear correlation coefficients (R_k, R_o) were further calculated using the two different methods (Kissinger, Ozawa-Doyle). The detailed parameters for the exothermic process of 1 are provided in Table S2 (the subscripts "k" and "o" represent the corresponding method of Kissinger and Ozawa, respectively). The results indicated that T_p increased along with the increased heating rate. In addition, the calculated kinetic parameters from two different approaches were essentially consistent. Its Arrhenius equation was conducted as ln k=8.932 0-137.58×10³/(RT) using the obtained average activation energy E of E_k and E_o, which are related to the inherent thermal decomposition rate constant of 1.

  2.4   Sensitivity tests

  Sensitivity is an essential indicator for evaluating the safety performance of explosives^[27-28]. To explore the usefulness of ECP 1 as an explosive, the sensitivity measurement was performed using the standard BAM instrument. 20 mg prepared sample 1 was hit by a drop hammer with 2 kg. As a result, the drop-weight experiment indicated that 1 showed a better impact sensitivity with an energy of 40 J at a height of 200 cm. Additionally, there was no sensitivity to friction up to 360 N. For comparison, TNT was measured under the same conditions, and its impact and friction sensitivity was 15.0 J and 120 N. These values were consistent with previously reported values. According to the above results, compound 1 exhibited low sensitivity to both impact and frictional stimulation, indicating a low sensitivity of 1 to the environment.

  2.5   Detonation performance

  To investigate the detonation performance of ECP 1, we employed the density functional theory (DFT) method to get its detonation energy (ΔE_det) and further combined it with the linear equation (ΔH_det=1.127ΔE_det+0.046) to determine the detonation enthalpy (ΔH_det) of 1. This method is an effective and known strategy for predicting the detonation enthalpy of explosive materials in the field. Moreover, according to the reported H₂O-CO₂ theory^[29], the concluding decomposition products of 1 are predicted to be cobalt, nitrogen, carbon, as well as ammonia. The relevant combustion reaction was represented as Eq.3, and the calculated theoretical detonation heat was 6.98 kJ·g^-1. The relevant computational parameters for 1 are listed in Table S3. Furthermore, using the Kamlet-Jacobs equation^[30], the theoretical detonation velocity (D) and detonation pressure (p) of 1 can be further estimated by following Eq.4, 5, and 6:

  $ \mathrm{Co}_4 \mathrm{C}_{20} \mathrm{H}_{24} \mathrm{O}_8 \mathrm{~N}_{40} \rightarrow 4 \mathrm{Co}+8 \mathrm{H}_2 \mathrm{O}+\frac{8}{3} \mathrm{NH}_3+20 \mathrm{C}+\frac{56}{3} \mathrm{~N}_2 $

  (3)

  $ D=1.01 {\mathit{\Phi}}^{1 / 2}(1+1.30 \rho) $

  (4)

  $ P=1.558 {\mathit{\Phi}} \rho^2 $

  (5)

  $ {\mathit{\Phi}}=15.495 N(M {\mathit{\Phi}})^{1 / 2} $

  (6)

  where Q is the heat of detonation (kJ·g^-1), N is the moles of detonation gases per gram of explosive (mol·g^-1), M is the average molecular weight of the gases, and ρ is the density of explosive (g·cm^-3). We also compared the D, p, and other energy parameters of 1 with several known energetic materials, and the detailed experimental results and relevant physicochemical properties are listed in Table 2. The heat of detonation of ECP 1 was found to be superior to known energetic materials.

  Table 2

  

  Table 2.  Comparison of key energetic parameters between 1 and some known energetic compounds (ECs)

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  EC	wNa / %	ρb / (g·cm-3)	Tdecc / ℃	Q / (kJ·g-1)	D / (m·s-1)	p / GPa	IS / J	FS / N
  1	47.12	2.08	230	6.98	8 349	33.51	> 40	> 360
  TNT[31]	18.50	1.653	244	5.10	7 178	20.5	15	353
  RDX[31]	37.80	1.800	210	6.019	8 906	34.1	7.5	120
  CHP[32]	14.71	1.948	194	5.225	8 225	31.73	0.5	—
  NHP[32]	33.49	1.983	220	5.727	9 184	39.69	—	—
  ZnHHP[33]	23.61	2.117	293	2.926	7 016	23.58	—	—
  CHHP[33]	23.58	2.000	231	3.135	6 205	17.96	0.8	—
  ATRZ-1[34]	53.35	1.680	243	15.123	9 160	35.68	22.5	—
  ATRZ-2[34]	43.76	2.160	257	5.773	7 773	29.70	30	—
  IFMC-1[35]	47.26	1.468	392	23.492	8 210	26.23	> 40	> 360
  a Mass fraction of nitrogen in the energetic material; b Density from X-ray diffraction analysis; c Thermal decomposition temperature.

  2.6   Application performance

  AP and RDX is the main ingredient in solid propellants, and their application can greatly promote the performance of solid propellants. As described in the introduction, the energy characteristics of propellants can be directly impacted by the combustion decomposition of oxidizer AP and RDX^[36]. Based on this, we explored the impact of ECP 1 as a combustion catalyst on the combustion decomposition process of AP and RDX. To get the target sample, single crystal 1 was prepared into powder after grinding and mixed with the oxidizer component AP/RDX in a mass ratio of 1∶3.

  Under a nitrogen atmosphere, both the combustion decomposition behavior of pure AP and the mixture sample 1+AP were investigated by the DSC technology. Experimental results illustrate that there were one endothermic peak and two exothermic peaks for pure AP (Fig. 6). The endothermic peak at 240 ℃ is the crystalline transformation peak of AP, in which the crystal system transforms from monoclinic into cubic. Furthermore, The exothermic peaks at 335 and 440 ℃ are caused by the thermal decomposition of AP, which corresponds to decomposition exothermic processes of low-temperature as well as high-temperature^[37]. During the process, partially AP decomposes into porous material and releases heat, and then the remaining solid further decomposes into volatile substances. For the mixture 1+AP, its DSC curve exhibited a similar peak to pure AP at 240 ℃, implying that 1 has a negligible effect on the crystalline transformation of AP. In contrast to the two exothermic peaks observed in AP, the mixture of AP with 1 overlapped one sharp exothermic peak at 310℃, and the peak temperature advanced by 25 ℃. After catalytic combustion, the particle size of combustion residues for sample (1+AP) was smaller and more dispersed than that of compound 1 (Fig. 7). From the above results, it is inferred that ECP 1 can promote the combustion decomposition of AP. The acceleration effects can be reasonably attributed to the huge amount of energy and the production of metal in the combustion process.

  Figure 6

  

  Figure 6.  DSC curves of pure AP and the mixture sample particles

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  Figure 7

  

  Figure 7.  SEM images of (a, b) single crystal 1 and (c, d) combustion residues from the mixture sample of 1+AP particles

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  We further studied the influence of ECP 1 on the combustion performance of oxidizer components RDX. The DSC curve for pure RDX showed an endothermic peak at 204 ℃ and an exothermic peak at 237 ℃ (Fig. 8). The endothermic peak represents the melting of RDX, while the exothermic peak corresponds to the thermal decomposition of RDX. After that, RDX underwent a slow decomposition process until it was completely decomposed^[38]. The mixture of 1+RDX exhibited a similar endothermic process to that of pure RDX at 204 ℃, but its exothermic peak temperature (226 ℃) was lower than pure RDX (237 ℃). Therefore, 1 exhibits a promotion impact on the combustion decomposition of RDX. In comparison, 1 has better promotion performance on AP than RDX.

  Figure 8

  

  Figure 8.  DSC curves of pure RDX and the mixture sample particles

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  3.   Conclusions

  To summarize, we successfully synthesized a novel energetic coordination polymer [Co₄(HBTI)₄(H₂O)₈] (1), using the hydrothermal method and the energetic ligand 4, 5-bistetrazole-imidazole (H₃BTI). The non-isothermal kinetics during the decomposition were systematically investigated by combining two different methods of Kissinger and Ozawa-Doyle. In addition, the calculated heat of detonation of 1 was found to be significantly superior to known energetic materials like hexogen (RDX) and trinitrotoluene(TNT). Furthermore, DSC experiments revealed that ECP 1 is capable of catalyzing the thermal decomposition reactions of AP and RDX. Based on its environmental friendliness, low sensitivities, and good detonation and catalytic performance, 1 can act as a HEDM that could potentially be utilized in explosives and propellants.

  
  Supporting information is available at http://www.wjhxxb.cn
  
• 1. [1]

     Zhang C, Sun C G, Hu B C, Yu C M, Lu M. Synthesis and characterization of the pentazolate anion cyclo-N5^- in (N₅)₆(H₃O)₃(NH₄)₄Cl[J]. Science, 2017, 355(6323):  374-376. doi: 10.1126/science.aah3840

  2. [2]

     Zhang J H, Guo Z C, Song Y L, Hao W J, Peng R F, Jin B. Hydrogen bond and 3D frameworks to reconcile the conflict between safety and detonation performance in energetic metal-organic frameworks[J]. Chem. Eng. J., 2023, 453(2):  139726.

  3. [3]

     Ma Q, Gu H, Huang J L, Liu D B, Li J S, Fan G J. Synthesis and characterization of new melt-cast energetic salts: Dipotassium and diaminoguanidinium N, N′-dinitro-N, N′-bis(3-dinitromethyl-furazanate-4-yl)methylenediamine[J]. Propellants Explos. Pyrotech., 2018, 43(1):  90-95. doi: 10.1002/prep.201700164

  4. [4]

     Wu S, Li M, Yang Z Y, Xia Z Q, Liu B, Yang Q, Wei Q, Xie G, Chen S P, Gao S L, Lu J Y. Synthesis and characterization of a new energetic metal-organic framework for use in potential propellant compositions[J]. Green Chem., 2020, 22(15):  5050-5058. doi: 10.1039/D0GC01594F

  5. [5]

     Xu J G, Lin S J, Li X Z, Wu H F, Lu J, Wang W F, Chen J, Zheng F, Guo G C. Energetic azide-based coordination polymers: Sensitivity tuning through diverse structural motifs[J]. Chem. Eng. J., 2020, 390(15):  124587.

  6. [6]

     Zhang W Q, Zhang J H, Deng M C, Qi X J, Nie F D, Zhang Q H. A promising high-energy-density material[J]. Nat. Commun., 2017, 8(1):  181-185. doi: 10.1038/s41467-017-00286-0

  7. [7]

     Zhang H B, Zhang M J, Lin P, Malgras V, Tang J, Alshehri S M, Yamauchi Y, Du S W, Zhang J. A highly energetic N-rich metal-organic framework as a new high-energy-density material[J]. Chem.-Eur. J., 2016, 22(3):  1141-1145. doi: 10.1002/chem.201503561

  8. [8]

     Li Q, Yu M H, Xu J, Li A L, Hu T L, Bu X H. Two new metal-organic frameworks based on tetrazole-heterocyclic ligands accompanied by in situ ligand formation[J]. Dalton Trans., 2017, 46(10):  3223-3228. doi: 10.1039/C7DT00005G

  9. [9]

     Yang Q, Yang G L, Ge J, Yang L L, Song X X, Wei Q, Xie G, Chen S P, Gao S L. Thermodynamic properties of 3D copper(Ⅱ)-MOFs assembled by 1H-tetrazole[J]. J. Therm. Anal. Calorim., 2016, 128(2):  1175-1182.

  10. [10]

      Zhong Y, Li Z M, Xu Y Q, Lei G R, Zhang J G, Zhang T L. Transition metal(Mn/Co/Ni/Cu) complexes based on 1‑ethylimidazole and di-cyandiamide: Syntheses, characterizations, and catalytic effects on the thermal decomposition of ammonium perchlorate[J]. J. Energ. Mater., 2021, 39(2):  215-227. doi: 10.1080/07370652.2020.1770897

  11. [11]

      Zhang J H, Zhang Q H, Vo T T, Parrish D A, Shreeve J. Energetic salts with π-stacking and hydrogen-bonding interactions lead the way to future energetic materials[J]. J. Am. Chem. Soc., 2015, 137(4):  1697-1704. doi: 10.1021/ja5126275

  12. [12]

      刘进剑, 刘祖亮, 成健, 方东, 王俊. 含能配合物2, 6-二氨基-3, 5二硝基1-氧化物合钴(Ⅲ)的合成、晶体结构及催化性能[J]. 无机化学学报, 2013,29,(2): 289-294. doi: 10.3969/j.issn.1001-4861.2013.02.011LIU J J, LIU Z L, CHENG J, FANF D, WANG J. Synthesis, crystal structure and catalytic properties of 2, 6-diamino-3, 5-dinitropyridine-1-oxide cobalt(Ⅲ)[J]. Chinese J. Inorg. Chem., 2013, 29(2):  289-294. doi: 10.3969/j.issn.1001-4861.2013.02.011

  13. [13]

      Li X, Yang Q, Wei Q, Xie G, Chen S P, Gao S L. Axial substitution of a precursor resulted in two high-energy copper(Ⅰ) complexes with superior detonation performances[J]. Dalton Trans., 2017, 46(38):  12893-12900. doi: 10.1039/C7DT02179H

  14. [14]

      Yang Q, Yang G L, Zhang W D, Zhang S, Yang Z h, Xie G, Wei Q, Chen S P, Gao S L. Superior thermostability, good detonation property, insensitivity and effect on the thermal decomposition of ammonium perchlorate of a new solvent-free 3D energetic Pb(Ⅱ)-MOF[J]. Chem.-Eur. J., 2017, 23(38):  9149-9155. doi: 10.1002/chem.201701325

  15. [15]

      Guo Z Q, Wu Y L, Deng C Q, Yang G P, Zhang J G, Sun Z H, Ma H X, Gao C, An Z W. Structural modulation from 1D chain to 3D framework: Improved thermostability, insensitivity, and energies of two nitrogen-rich energetic coordination polymers[J]. Inorg. Chem., 2016, 55(21):  11064-11071. doi: 10.1021/acs.inorgchem.6b01630

  16. [16]

      Qu X N, Yang Q, Han J, Wei Q, Xie G, Chen S P, Gao S L. High performance 5-aminotetrazole-based energetic MOF and its catalytic effect on decomposition of RDX[J]. RSC Adv., 2016, 6(52):  46212-46217. doi: 10.1039/C6RA07301H

  17. [17]

      Shen C, Xu Y G, Lu M. A series of high-energy coordination polymers with 3, 6-bis(4-nitroamino-1, 2, 5-oxadiazol-3-yl)-1, 4, 2, 5-dioxadiazine, a ligand with multi-coordination sites, high oxygen content and detonation performance: Syntheses, structures, and performance[J]. J. Mater. Chem. A, 2017, 5(35):  18854-18861. doi: 10.1039/C7TA05479C

  18. [18]

      Kizhnyaev V N, Golobokova T V, Pokatilov F A, Vereshchagin L I, Estrin Y I. Synthesis of energetic triazole- and tetrazole-containing oligomers and polymers[J]. Chem. Heterocycl. Compd., 2017, 53(6/7):  682-692.

  19. [19]

      Kang L, Wei Z X, Song J F, Qu Y Y, Wang Y L. Two new energetic coordination compounds based on tetrazole-1-acetic acid: Syntheses, crystal structures and their synergistic catalytic effect for thermal decomposition of ammonium perchlorate[J]. RSC Adv., 2016, 6(40):  33332-33338. doi: 10.1039/C6RA02034H

  20. [20]

      Chen D, Huang S L, Zhang Q, Yu Q, Zhou X Q, Li H Z, Li J S. Two nitrogen-rich Ni(Ⅱ) coordination compounds based on 5, 5-azotetrazole: Synthesis, characterization and effect on thermal decomposition for RDX, HMX and AP[J]. RSC Adv., 2015, 5(41):  32872-32879. doi: 10.1039/C5RA02464A

  21. [21]

      Guo M. 4, 5-Bis(1H-tetrazol-5-yl)-1H-imidazole monohydrate[J]. Acta Crystallogr., Sect. E, 2009, E65(6):  O1403-U2972.

  22. [22]

      Tang Y X, Kumar D, Shreeve J M. Balancing excellent performance and high thermal stability in a dinitropyrazole fused 1, 2, 3, 4-tetrazine[J]. J. Am. Chem. Soc., 2017, 139(39):  13684-13687. doi: 10.1021/jacs.7b08789

  23. [23]

      Zhai C, Yang Z Y, Xu D, Wang Z K, Hao X Y, Shi Y J, Yang G W, Li Q Y. pH dependent synthesis of two zinc(Ⅱ) compounds derived from 5-aminotetrazole-1-isopropanoic acid for treatment of cancer cells[J]. J. Solid State Chem., 2017, 258:  156-162.

  24. [24]

      Xu Y Q, Wang Y N, Zhong Y, Lei G R, Li Z M, Zhang J G, Zhang T L. Transition metal complexes based on hypergolic anions for catalysis of ammonium perchlorate thermal decomposition[J]. Energy Fuels, 2020, 34(11):  14667-14675. doi: 10.1021/acs.energyfuels.0c02570

  25. [25]

      Kissinger H E. Reaction kinetics in differential thermal analysis[J]. Anal. Chem., 1957, 29(11):  1702-1706. doi: 10.1021/ac60131a045

  26. [26]

      Ozawa T. A new method of analyzing thermogravimetric data[J]. Bull. Chem. Soc. Jpn., 1965, 38(11):  1881-1886. doi: 10.1246/bcsj.38.1881

  27. [27]

      Tang Y X, He C L, Mitchell L A, Shreeve J M. Potassium 4, 4′-bis (dinitromethyl)-3, 3′-azofurazanate: A highly energetic 3D metal-organic framework as a promising primary explosive[J]. Angew. Chem. Int. Ed., 2016, 128(18):  5655-5657. doi: 10.1002/ange.201601432

  28. [28]

      Zhang S, Liu X Y, Yang Q, Su Z Y, Gao W J, Wei Q, Xie G, Chen S P, Gao S L. A new strategy for storage and transportation of sensitive high energy materials: Guest-dependent energy and sensitivity of 3D metal-organic-framework-based energetic compounds[J]. Chem.-Eur. J., 2014, 20(26):  7906-7910. doi: 10.1002/chem.201402783

  29. [29]

      Kamlet M J, Hurwitz H. Chemistry of detonations. Ⅳ. Evaluation of a simple predictional method for detonation velocities of C—H—N—O explosives[J]. J. Chem. Phys., 1968, 48(8):  3685-3692. doi: 10.1063/1.1669671

  30. [30]

      Wang Y, Zhang J C, Su H, Li S H, Zhang S W, Pang S. P.. A simple method for the prediction of the detonation performances of metal-containing explosives[J]. J. Phys. Chem. A, 2014, 118(25):  4575-4581. doi: 10.1021/jp502857d

  31. [31]

      Yang G L, Li X, Wang M, Xia Z Q, Yang Q, Wei Q, Xie G, Chen S P, Gao S L, Lu J. Improved detonation performance via coordination substitution: Synthesis and characterization of two new green energetic coordination polymers[J]. ACS Appl. Mater. Interfaces, 2021, 13(1):  563-569. doi: 10.1021/acsami.0c18271

  32. [32]

      Bushuyev O S, Brown P, Maiti A, Gee R H, Peterson G R, Weeks B L, Hope-Weeks L J. Ionic polymers as a new structural motif for high-energy-density materials[J]. J. Am. Chem. Soc., 2012, 134(3):  1422-1425. doi: 10.1021/ja209640k

  33. [33]

      Bushuyev O S, Peterson G R, Brown P, Maiti A, Gee R H, Weeks B L, Hope-Weeks L J. Metal-organic frameworks (MOFs) as safer, structurally reinforced energetics[J]. Chem.-Eur. J., 2013, 19(5):  1706-1711. doi: 10.1002/chem.201203610

  34. [34]

      Li S H, Wang Y, Cai Q, Zhao X X, Zhang J C, Zhang S W, Pang S P. 3D energetic metal-organic frameworks: Synthesis and properties of high energy materials[J]. Angew. Chem. Int. Ed., 2013, 52(52):  14031-14035. doi: 10.1002/anie.201307118

  35. [35]

      Qin J S, Zhang J C, Zhang M, Du D Y, Li J, Su Z M, Wang Y Y, Pang S P, Li S. H, Lan Y Q. A highly energetic N-rich zeolite-like metal-organic framework with excellent air stability and insensitivity[J]. Adv. Sci., 2015, 2(12):  1500150. doi: 10.1002/advs.201500150b03397

  36. [36]

      Shusser M, Culick F E C, Cohen N S. Combustion response of ammonium perchlorate composite propellants[J]. J. Propul. Power, 2002, 18(5):  1093-1100. doi: 10.2514/2.6039

  37. [37]

      Cheng J, Zheng Y, Li Z M, Liu Z L, Li L X, Zhao F Q, Xu S Y. Catalytic reaction of ammonium perchlorate with energetic cobalt complex of 2, 6-diamino-3, 5-dinitropyrazine-1-oxide during thermal decomposition process[J]. J. Therm. Anal. Calorim., 2017, 129(3):  1875-1885. doi: 10.1007/s10973-017-6263-y

  38. [38]

      Hsieh W H, Li W Y. Combustion behavior and thermochemical properties of RDX-based solid propellants[J]. Propellants Explos. Pyrotech., 2015, 23(3):  128-136.

• 

  Scheme 1  Synthetic diagram of ligand H₃BTI

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  Figure 1  Coordination polyhedron for Co ions in ECP 1

  Symmetry code: A: 2-x, 1-y, -z.

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  Figure 2  Ellipsoidal diagram of molecular structure of ECP 1

  The ellipsoid contour has 50% probability levels in the structure; Symmetry code: A: 2-x, 1-y, -z.

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  Figure 3  Three-dimensional supramolecular configuration of ECP 1 along the b-axis

  Symmetry codes: B: 1-x, 1-y, -z; C: -1+x, y, z; D: -1/2+x, 1/2-y, 1/2+z.

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  Figure 4  TG curve of ECP 1

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  Figure 5  DSC curve of ECP 1

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  Figure 6  DSC curves of pure AP and the mixture sample particles

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  Figure 7  SEM images of (a, b) single crystal 1 and (c, d) combustion residues from the mixture sample of 1+AP particles

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  Figure 8  DSC curves of pure RDX and the mixture sample particles

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  Table 1.  Structure refinements and crystalline information of ECP 1

  Parameter	1
  Formula	C20H24Co4N40O8
  Formula weight	1 188.51
  Crystal system	Monoclinic
  Space group	P21/n
  a / nm	7.501(6)
  b / nm	16.013(12)
  c / nm	16.186(12)
  β / (°)	102.517(14)
  V / nm3	1 898(2)
  Z	2
  Dc / (g·cm-3)	2.08
  μ / mm-1	1.826
  F(000)	1 192
  GOF on F2	1.023
  R1, wR2 [I > 2σ(I)]	0.081 1, 0.209 9
  R1, wR2 (all data)	0.124 4, 0.234 3

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  Table 2.  Comparison of key energetic parameters between 1 and some known energetic compounds (ECs)

  EC	wNa / %	ρb / (g·cm-3)	Tdecc / ℃	Q / (kJ·g-1)	D / (m·s-1)	p / GPa	IS / J	FS / N
  1	47.12	2.08	230	6.98	8 349	33.51	> 40	> 360
  TNT[31]	18.50	1.653	244	5.10	7 178	20.5	15	353
  RDX[31]	37.80	1.800	210	6.019	8 906	34.1	7.5	120
  CHP[32]	14.71	1.948	194	5.225	8 225	31.73	0.5	—
  NHP[32]	33.49	1.983	220	5.727	9 184	39.69	—	—
  ZnHHP[33]	23.61	2.117	293	2.926	7 016	23.58	—	—
  CHHP[33]	23.58	2.000	231	3.135	6 205	17.96	0.8	—
  ATRZ-1[34]	53.35	1.680	243	15.123	9 160	35.68	22.5	—
  ATRZ-2[34]	43.76	2.160	257	5.773	7 773	29.70	30	—
  IFMC-1[35]	47.26	1.468	392	23.492	8 210	26.23	> 40	> 360
  a Mass fraction of nitrogen in the energetic material; b Density from X-ray diffraction analysis; c Thermal decomposition temperature.

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