Top Development of Green-Light Pyrotechnics: Hypergolic Cu(II)-Based Coordination Polymers

Guided by structural chemistry and crystallization chemistry, two coordination polymers Cu(AOCA)2(NO3)2 (ECPs-1) and [Cu(PZCA)(NO3)](NO3) (ECPs-2) were prepared by reacting 4-amino-1,2,5-oxadiazole-3-carbohydrazide (AOCA) and pyrazole-4-carbohydrazide (PZCA) with Cu(NO3)2, respectively, and their structures and properties were characterized. Single-crystal XRD proved that ECPs-1 was a solvent-free 0D structure, while ECPs-2 was a one-dimensional (1D) structure containing coordinated water. TG-DSC tests manifested that ECPs-1 had better thermal stability (Tted = 159 °C), while ECPs-2 had a better decomposition rate (ΔT = 25 °C). In addition, their safety was evaluated by measuring their combustion heat and mechanical sensitivity. Using only ECPs-1 and ECPs-2 as the main components of the pyrotechnic agents, the combustion performance and flame color effect were studied. The results proved that they both have the potential to be used as pyrotechnics, and the purity of ECPs-1 is higher, reaching 79%.