3D high-energy-density and low sensitivity materials: synthesis, structure and physicochemical properties of an azide-Cu(II) complex with 3,5-dinitrobenzoic acid

A novel 3D energetic coordination polymer of azide-Cu(II), Cu(3,5-DNBA)(N-3), was synthesized and structurally characterized by single crystal X-ray diffraction, where 3,5-DNBA represents 3,5dinitrobenzoic acid. Structural analysis reveals that the central Cu(II) ion coordinates with two azide anions and three 3,5-dinitrobenzoic acid anions to form a five-coordinated tetragonal pyramid structure. Remarkably, one oxygen atom in the nitro group displays rare coordination to the Cu(II) ions in the complex. The as-prepared compound showed abrupt thermal decomposition at 268 degrees C, representing explosive performance and superior thermostability based on DSC and TG-DTG analyses. Sensitivity tests revealed that the title complex was insensitive to external stimuli. The kinetic parameters of an exothermic process for the complex were studied by Kissinger's and Ozawa-Doyle's methods. In addition, the constant-volume combustion energy of the complex was determined using a precise rotating-bomb calorimeter, and the standard molar enthalpy of combustion and the standard molar enthalpy of formation were calculated.