Access to Green Pyrotechnic Compositions via Constructing Coordination Polymers: A New Approach to the Application of 3,4-Dinitropyrazole

Abstract

Alkali and alkaline-earth metal salts with 3,4dinitropyrazole (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.

Lithium-Promoted Formation of M-2AZTO-Li (M = N2H5+ or NH3OH+ and AZTO = Anion of 1-Hydroxytetrazole-5-hydrazide)-Type “Quaternary” Complexes with Nitrogen-Rich Characteristics: Construction of Novel Insensitive Energetic Materials

“…Energetic complexes are typically produced in the following three forms (Figure A–C): (A) high-energy anion-metal-cation, − (B) high-energy cation-metal-ion-oxygen-rich-anion, − and (C) azole anion-heavy metal-cation-azide anion. − The foregoing three types of complexes exhibit different characteristics in terms of their physicochemical properties, and of these, types A and B tend to form high-energy complexes with a high oxygen content; a majority of such complexes also have a high mechanical sensitivity, facilitating their use as primary explosives, oxidizer combustion promoters, or heat-resistant explosives. Furthermore, C-type complexes are more likely to form nitrogen-rich structures and exhibit favorable thermal stabilities.…”

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

“…(2) the ligands for preparing ECPs are nitro-rich compounds, which greatly increases the difficulty of synthesis and the cost of preparing pyrotechnics; and (3) the colors of pyrotechnics are single, and they are mostly concentrated in red [Li(I)-ECPs, 8 Sr(II)-ECPs], 11 and green [Ba(II)-ECPs]. 10,12 Although Cao 13 and Dong 14 have developed a series of new pyrotechnic powders, there are many fatal defects, such as poor flame color effect, lack of characterization of emission wavelength, no flame purity test, and unprofessional flame As we all know, Cu(I) is a special metal, and its different forms of existence will produce different colors: CuCl or CuBr is the source of blue light and CuOH produces green light. 15,16 The multirole play makes it possible for Cu-based ECPs to construct different colors of pyrotechnic agents.…”

“…Although Cao and Dong have developed a series of new pyrotechnic powders, there are many fatal defects, such as poor flame color effect, lack of characterization of emission wavelength, no flame purity test, and unprofessional flame test. Most importantly, in the pyrotechnic agents they studied, additional oxidizing or reducing agents were added, which did not fully exploit the advantages of ECPs.…”

Ligand as Buffer for Improving Chemical Stability of Coordination Polymers

“…Coordination polymers (CPs) are inorganic–organic hybrid crystalline materials assembled from metal ions as nodes and polydentate organic ligands as linkers via M–O or M–N coordination bonds. − They feature infinite one-, two-, and three-dimensional (1D, 2D, and 3D) network structures and play pivotal roles in catalysis, gas separation, sensing, anticounterfeiting, magnetism, etc. − However, the poor chemical stability always inhibits widespread application of CPs. , On one hand, the weak M–O or M–N coordination bonds are fragile in polar solvents like water. On the other hand, acidic or alkaline environments provide an ionic platform to further break the coordination bonds.…”