Fine-Tuning the Energetic Properties of Complexes through Ligand Modification

The modification of the properties of energetic materials is significant not only for gaining insight into the correlation between the structure and properties but also for various applications. In this study, three bis-1,2,4-triazole derivatives containing different energetic groups such as NH₂, NO₂, and NHNO₂ (5,5′-diamino-3,3′-bis-1,2,4-triazole (H₂DABT), 5,5′-dinitro-3,3′-bis-1,2,4-triazole (H₂DNBT) and 5,5′-dinitroimino-3,3′-bis-1,2,4-triazole (H₂DNABT)) were chosen as ligands to tune the structures and energetic properties of their complexes. Single-crystal X-ray diffraction studies show that as the modifying groups on the bis-1,2,4-triazole ligand were varied from NH₂ to NO₂ and NHNO₂, the densities of the resultant complexes gradually increased from 1.838 g cm^-3 to 1.978 g cm^-3 and 2.049 g cm^-3 for Cu-based complexes, while for Zn-based complexes, the densities also showed a gradual increase from 1.818 g cm^-3 to 2.044 g cm^-3 and 2.056 g cm^-3. Additionally, the thermal stabilities and sensitivities of these complexes were also determined, and their detonation properties were calculated by the modified Kamlet method. As a result, the energetic performances of these resultant complexes were successfully modulated. This work may provide an effective approach to modulate the energetic properties of complexes via introduction of different energetic groups into the ligands.