Skip to main content

Higher performing and less sensitive CN7-based high-energy-density material



The highest nitrogen-containing binary C-N anion, 5-azido-tetrazolate (CN7), has attracted significant attention owing to its high-energy content. Due to its relative instability and high sensitivity, it is an ongoing challenge to develop more stable and less sensitive novel materials based on CN7. Towards this goal, we have stabilized the CN7 anion without compromising its energetic performance by formation of its NH3OH+ salt containing an additional NH2OH molecule, [NH3OH][CN7][NH2OH] (2). It possesses the best detonation performance and the lowest mechanical sensitivity among all known CN7-based materials. The structure-property relationship was elucidated through a careful investigation of the noncovalent interactions in the crystal lattice and the important role of the NH2OH moiety. In addition, the structurally related compound [NH3OH][CN7] (1) was also studied.


具有最高氮含量的二元C-N阴离子, 叠氮四唑离子—CN7, 因其极高的能量密度受到广泛关注, 但由于CN7的不稳定性, 以此合成新型低感的高能量密度材料存在极大难度. 本文制备出一种新型高能加合物[NH3OH][CN7][NH2OH], 该化合物在所有已知的CN7化合物中表现出最好的爆轰性能与最低的机械感度. 为了探索NH2OH分子对含能化合物性质的影响, 我们合成了另一种含能盐[NH3OH][CN7], 并对其与加合物[NH3OH][CN7][NH2OH]的结构与性能进行了比较. 结果表明NH2OH及其氢键作用对于改善CN7的热稳定性和机械感度起到了重要作用.


  1. 1

    Li YC, Qi C, Li SH, et al. 1,1′-Azobis-1,2,3-triazole: a high-nitrogen compound with stable N8 structure and photochromism. J Am Chem Soc, 2010, 132: 12172–12173

    CAS  Article  Google Scholar 

  2. 2

    Klapötke TM, Martin FA, Stierstorfer J. C2N14: an energetic and highly sensitive binary azidotetrazole. Angew Chem Int Ed, 2011, 50: 4227–4229

    Article  Google Scholar 

  3. 3

    Bennion JC, Chowdhury N, Kampf JW, et al. Hydrogen peroxide solvates of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. Angew Chem Int Ed, 2016, 55: 13118–13121

    CAS  Article  Google Scholar 

  4. 4

    Hu L, Yin P, Zhao G, et al. Conjugated energetic salts based on fused rings: insensitive and highly dense materials. J Am Chem Soc, 2018, 140: 15001–15007

    CAS  Article  Google Scholar 

  5. 5

    Baxter AF, Martin I, Christe KO, et al. Formamidinium nitroformate: an insensitive RDX alternative. J Am Chem Soc, 2018, 140: 15089–15098

    CAS  Article  Google Scholar 

  6. 6

    Tang Y, Yang H, Wu B, et al. Synthesis and characterization of a stable, catenated N11 energetic salt. Angew Chem Int Ed, 2013, 52: 4875–4877

    CAS  Article  Google Scholar 

  7. 7

    Wang PC, Xu YG, Wang Q, et al. Self-assembled energetic coordination polymers based on multidentate pentazole cyclo-N5. Sci China Mater, 2019, 62: 122–129

    CAS  Article  Google Scholar 

  8. 8

    Xu Y, Wang P, Lin Q, et al. Cationic and anionic energetic materials based on a new amphotère. Sci China Mater, 2019, 62: 751–758

    Article  Google Scholar 

  9. 9

    Zhang C, Sun C, Hu B, et al. Synthesis and characterization of the pentazolate anion cyclo-N5 in (N5)6(H3O)3(NH4)4Cl. Science, 2017, 355: 374–376

    CAS  Article  Google Scholar 

  10. 10

    Zhang C, Yang C, Hu B, et al. A symmetric Co(N5)2(H2O)4·4 H2O high-nitrogen compound formed by cobalt(II) cation trapping of a cyclo-N5 anion. Angew Chem Int Ed, 2017, 56: 4512–4514

    CAS  Article  Google Scholar 

  11. 11

    Xu Y, Wang Q, Shen C, et al. A series of energetic metal pentazolate hydrates. Nature, 2017, 549: 78–81

    CAS  Article  Google Scholar 

  12. 12

    Christe KO, Dixon DA, Vasiliu M, et al. How energetic are cyclo-pentazolates? Prop Explos Pyrotech, 2019, 22: 263–266

    Article  Google Scholar 

  13. 13

    Christe KO, Wilson WW, Sheehy JA, et al. N5+: a novel homoleptic polynitrogen ion as a high energy density material. Angew Chem Int Ed, 1999, 38: 2004–2009

    CAS  Article  Google Scholar 

  14. 14

    Zhang W, Wang K, Li J, et al. Stabilization of the pentazolate anion in a zeolitic architecture with Na20N60 and Na24N60 nanocages. Angew Chem Int Ed, 2018, 57: 2592–2595

    CAS  Article  Google Scholar 

  15. 15

    Sun C, Zhang C, Jiang C, et al. Synthesis of AgN5 and its extended 3D energetic framework. Nat Commun, 2018, 9: 1269–1275

    Article  Google Scholar 

  16. 16

    Yang C, Zhang C, Zheng Z, et al. Synthesis and characterization of cyclo-pentazolate salts of NH4+, NH3OH+, N2H5+, C(NH2)3+, and N(CH3)4+. J Am Chem Soc, 2018, 140: 16488–16494

    CAS  Article  Google Scholar 

  17. 17

    Xu Y, Lin Q, Wang P, et al. Stabilization of the pentazolate anion in three anhydrous and metal-free energetic salts. Chem Asian J, 2018, 13: 924–928

    CAS  Article  Google Scholar 

  18. 18

    Arp HPH, Decken A, Passmore J, et al. Preparation, characterization, X-ray crystal structure, and energetics of cesium 5-cyano-1,2,3,4-tetrazolate: Cs[NCCNNNN]. Inorg Chem, 2000, 39: 1840–1848

    CAS  Article  Google Scholar 

  19. 19

    Fischer N, Hüll K, Klapötke TM, et al. 5,5′-Azoxytetrazolates—a new nitrogen-rich dianion and its comparison to 5,5′-azotetrazolate. Dalton Trans, 2012, 41: 11201–11211

    CAS  Article  Google Scholar 

  20. 20

    Akutsu Y, Tamura M. Calculations of heats of formation for azoles with PM3. J Energetic Mater, 1993, 11: 205–217

    CAS  Article  Google Scholar 

  21. 21

    Hiskey MA, Chavez DE, Naud DL, et al. Progress in high-nitrogen chemistry in explosives, propellants and pyrotechnics. Proc Int Pyrotech Semin, 2000, 27: 3–14

    Google Scholar 

  22. 22

    Klapötke TM, Piercey DG, Rohrbacher F, et al. Synthesis and characterization of energetic salts of the (C4N122−) dianion. Z anorg allg Chem, 2012

  23. 23

    Klapotke TM, Stierstorfer J. The CN7 anion. J Am Chem Soc, 2009, 131: 1122–1134

    CAS  Article  Google Scholar 

  24. 24

    Stierstorfer J, Klapötke TM, Hammerl A, et al. 5-Azido-1H-tetrazole—improved synthesis, crystal structure and sensitivity data. Z anorg allg Chem, 2008, 634: 1051–1057

    CAS  Article  Google Scholar 

  25. 25

    Hammerl A, Klapötke TM. Tetrazolylpentazoles: nitrogen-rich compounds. Inorg Chem, 2002, 41: 906–912

    CAS  Article  Google Scholar 

  26. 26

    Hammerl A, Klapötke T, Nöth H, et al. Synthesis, structure, molecular orbital and valence bond calculations for tetrazole azide, CHN7. Propell Explos Pyrotech, 2003, 28: 165–173

    CAS  Article  Google Scholar 

  27. 27

    Tang Y, Gao H, Mitchell LA, et al. Enhancing energetic properties and sensitivity by incorporating amino and nitramino groups into a 1,2,4-oxadiazole building block. Angew Chem Int Ed, 2016, 55: 1147–1150

    CAS  Article  Google Scholar 

  28. 28

    Wiscons RA, Bellas MK, Bennion JC, et al. Detonation performance of ten forms of 5,5′-dinitro-2H,2H′-3,3′-bi-1,2,4-triazole (DNBT). Cryst Growth Des, 2018, 18: 7701–7707

    CAS  Article  Google Scholar 

  29. 29

    Sun Q, Liu Y, Li X, et al. Alkali metals-based energetic coordination polymers as promising primary explosives: crystal structures, energetic properties, and environmental impact. Chem Eur J, 2018, 24: 14213–14219

    CAS  Article  Google Scholar 

  30. 30

    Fischer D, Klapötke TM, Stierstorfer J. 1,5-Di(nitramino)tetrazole: high sensitivity and superior explosive performance. Angew Chem Int Ed, 2015, 54: 10299–10302

    CAS  Article  Google Scholar 

  31. 31

    Tang Y, Mitchell LA, Imler GH, et al. Ammonia oxide as a building block for high-performance and insensitive energetic materials. Angew Chem, 2017, 129: 5988–5992

    Article  Google Scholar 

  32. 32

    Klapötke TM, Piercey DG, Stierstorfer J. The taming of CN7: the azidotetrazolate 2-oxide anion. Chem Eur J, 2011, 46: 13068–13077

    Article  Google Scholar 

  33. 33

    Frisch MJ, Trucks GW, Schlegel HB, et al. Gaussian 09, Revision A.02, Gaussian, Inc., Wallingford, CT, 2009

    Google Scholar 

  34. 34

    Suceska M. EXPLO5 program, Version 6.01, 2011

  35. 35

    UN Recommendations on the transport of Dangerous Goods. Manual of Tests and Criteria, 5th rev. Ed. New York: United Nations Publication, 2009

    Google Scholar 

Download references


We gratefully acknowledge the National Natural Science Foundation of China (21771108 and 21805138), and the Natural Science Foundation of Jiangsu Province (BK20191291).

Author information




Author contributions Lin QH and Lu M designed the study. Sun Q and Li X performed the experiments and characterizations. Sun Q conducted the DFT calculations. Sun Q, Bamforth C and Murugesu M prepared the manuscript. All the authors discussed the results of the paper.

Corresponding authors

Correspondence to Qiu-han Lin or Muralee Murugesu or Ming Lu.

Ethics declarations

Conflict of interest The authors declare that they have no conflict of interest.

Additional information

Qi Sun was born in Jiangsu (China) in 1993. He is currently a PhD candidate under the supervision of Prof. Ming Lu at Nanjing University Of Science and Technology (NJUST) and a visiting student in the lab of Prof Muralee Murugesu. His research interest is the synthesis of nitrogen-rich high-energy-density materials.

Qiuhan Lin obtained his BSc in 2008 and PhD in 2013 from Beijing Institute of Technology (BIT), China. His current research interest is the synthesis and crystal engineering of energetic salts.

Muralee Murugesu received his PhD degree from the University of Karlsruhe in 2002. He undertook postdoctoral research at the University of Florida, University of California, Berkeley and the University of California, San Francisco. He is currently a full professor at the University of Ottawa. His research focuses on novel nanoscale materials and highly energetic materials.

Ming Lu obtained his BSc in 1984, MSc in 1989 and PhD in 1999 at NJUST. His current research interest is focused on the synthesis and crystal engineering of energetic materials, pharmaceutical intermediates and green chemistry.

Supplementary Information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sun, Q., Li, X., Bamforth, C. et al. Higher performing and less sensitive CN7-based high-energy-density material. Sci. China Mater. 63, 1779–1787 (2020).

Download citation


  • high nitrogen
  • binary C-N anion
  • hydrogen bonds
  • high-energy-density material