Construction of zwitterionic 3D hydrogen-bonded networks: Exploring the upper-limit of thermal stability in ternary CHN-based energetic materials

Two energetic zwitterionic CHN compounds 5-(1,3-diamino-5-iminio-1,5-dihydro-4H-1,2,4-triazol-4-yl)tetrazole (5) and 5-(6,7-diamino-3-iminio-3H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2(7H)-yl)tetrazole (6) were synthesized effectively by using a straightforward one-step synthetic route. With a rational arrangement of amino and tetrazole units as hydrogen bond (HB) donors and acceptors, 6 has more HB acceptors and displays a layer-by-layer structure. In comparison, the crystal packing of 5 displays twisted layers. In addition, the N-amino group of 6 contributes to inter-layer hydrogen-bonded interactions, thereby giving rise to a three-dimensional hydrogen-bonded network. Benefiting from unique structural features, the decomposition temperature of 6 is 371 °C, which approaches the relatively excellent among energetic ternary CHN compounds. Additionally, 6 exhibits good detonation performance and low impact sensitivity. This unique molecular structure, incorporating a fused nitrogen-rich zwitterionic 3D hydrogen-bonded interaction, provides a promising pathway for the development of high-nitrogen energetic materials.