Improved oxygen balance and effective energy density by coligand and dehydration strategy: Synthesis and characterization of two new energetic coordination polymers

Based on the excellent energetic ligand of N, N-bis(1H-tetrazole-5-yl)-amine (H₂bta) and coligand of oxalic acid (oa), Cu(Ⅱ) as the metal center ion, a new energetic coordination polymer (ECP), {[Cu₂(bta)₂(oa)(H₂O)₂]∙4H₂O}_n (1), was synthesized by hydrothermal method. Single crystal X-ray diffraction indicates that 1 possess 3D supramolecular configuration. Due to the existence of a large number of lattice water and coordination water molecules in 1, however, the effective energy density of 1 is limited. To further improve the performance of 1, according to its thermal decomposition behavior, we dehydrated 1 at 280 °C to obtain a new ECP [Cu₂(bta)₂(oa)]_n (2). The thermodynamic parameter of the decomposition process of 1 was discussed by Kissinger's and Ozawa's methods. Sensitivity tests show that 2 is more sensitivity to impact stimuli than 1, reflecting guest-dependent energy and sensitivity of ECPs. The theoretical calculation results show that 1 possess good detonation performances. The promotion effects of two ECPs on the combustion decomposition of ammonium perchlorate were studied using a differential scanning calorimetry method. Experimental results showed that 1 and 2 can be used as high energy density materials in the field of combustion promoter and the insensitive 1 can be regarded as a safe form for mass storge and transportation of sensitive 2.