Alkali and alkaline-earth metal salts with 3,4-dinitropyrazole (DNP) were synthesized by the reaction of DNP with stoichiometric amounts of the corresponding metal hydroxide-, oxide-, or carbonate-based highly pure salts, and products were fully characterized. Determination of single-crystal structures of all new complexes except for the lithium and strontium salts was performed by X-ray diffraction techniques. The cesium salt crystallized no water among them. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) manifested that these salts have satisfactory thermal stabilities with decomposition temperatures above 210 °C. They also showed that there exists strong bonding of crystallized water among lattices, which disappeared at temperatures equal to or above 115 °C except for salts MES-3, MES-4, and MES-9. In addition, the percentage of water contents was confirmed by using DSC and TGA methods. The constant-volume combustion heats of these metal salts containing DNP anions were measured using an oxygen bomb calorimeter due to their expectant interest in energetic materials, and their standard molar formation enthalpies were obtained. The investigated salts were found to be insensitive toward friction and impact. Findings of burning tests performed with experimental formulations using MES-1, MES-7, MES-8, and MES-9 certify that these four salts might be more promising candidates for application in green pyrotechnics.
Keywords: 3,4-dinitropyrazole; burning test; crystal structures; green compositions; pyrotechnics.