Differences in Performance among ECPs with Different Metal Centers Based on Highly Stable TzTO

The stability and detonation properties of energetic coordination polymers (ECPs) are usually directly related to the selection of ligands. However, different metals and ligands may form different structures, which will greatly affect the stability and detonation performance of ECPs. Three-dimensional (3D) energetic metal–organic frameworks (EMOFs) usually exhibit enhanced energetic performances and modest stability compared with one-dimensional (1D) and two-dimensional (2D) ECPs. In this work, an energetic internal salt H2TzTO (5-(1H-1,2,4-triazol-4-ium-3-yl)-1H-tetrazol-1-olate) with high stability was selected as the ligand and coordinated with four metal centers, Na(I), K(I), Co(II), and Ni(II), to form three ECPs, named [Na(HTzTO)(H2O)]n·0.5H2O, Co(HTzTO)2(H2O)2, and Ni(HTzTO)2(H2O)2·2H2O, and one EMOF [K(HTzTO)]n, respectively. The four compounds showed excellent thermal stability [decomposition temperature (Td) ≥ 263 °C] and detonation properties [detonation velocity (D) ≥ 8587 m·s–1 and detonation pressure (P) ≥ 33.8 GPa], but their properties are different due to the influence of the metal center and structure. Among them, [K(HTzTO)]n and Co(HTzTO)2(H2O)2 exhibit surprising thermal stability (Td = 344 and 347 °C, respectively) due to the formation of face-to-face π–π stacking in their structures, which greatly enhances the stability of the molecules.