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

Abstract

In this study, 3,6-bis(4-nitroamino-1,2,5-oxadiazol-3-yl)-1,4,2,5-dioxadiazine (H₂BNOD), with a relatively high oxygen content (37.41%) and good detonation performance (density = 1.817 g cm⁻³, detonation velocity = 8490 m s⁻¹), is used to prepare three new high-energy coordination polymers (CPs), {Ag₂(BNOD)(DMF)₂}_n (1), {Ag₂(BNOD)}_n (1a), and {Cu(BNOD)(H₂O)₆}_n (2), and a metal salt, Co(BNOD)(H₂O)₆ (3). Crystal structure analyses indicated that 1 is a 2D energetic coordination polymer (E-CP) with a three-dimensional wavy layer structure; 1a is a compact 3D E-CP without any solvent molecules. 2 exhibits a zigzag 1D chain structure, while the ionic salt 3 has a layer-by-layer structure (0D). Thermal analysis indicated that 1 and 1a exhibit good, as well as similar, thermostability (200 °C) owing to their compact framework structures. The enthalpy of formation is calculated from the constant-volume combustion energy. The four compounds exhibit detonation velocities (D) ranging from 7141 to 10 084 m s⁻¹, detonation pressures (P) ranging from 25.10 to 58.04 GPa, and heat of detonation (Q) values from 1.11 to 1.91 kcal g⁻¹. The impact sensitivities of the energetic salts were between 5 and 12 J, and their friction sensitivities ranged from 120 to 180 N, at the same level as those of RDX and HMX. Among these four compounds, 1a exhibits outstanding performance (D = 10 084 m s⁻¹, P = 58.04 GPa and Q = 1.91 kcal g⁻¹) with a compact 3D CP structure.