Multidimensional Energetic Coordination Polymers as Flame Colorants: Intriguing Architecture and Excellent Performance

Abstract

A flexible and multifunctional 4-hydroxy-3,5-dinitropyrazole (DNPO) ligand was produced while seeking "green" energetic coordination polymers (ECPs). A series of alkali metal and alkaline earth metal ECPs of DNPO were successfully prepared and comprehensively characterized using elemental analysis, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. All ECPs were characterized via single-crystal X-ray diffraction. They have high crystal densities ranging from 1.743 (ECP-6) to 3.399 g cm −3 (ECP-5). Furthermore, various shapes of zero-dimensional (0D), onedimensional (1D), two-dimensional (2D), and three-dimensional (3D) supramolecular structures were found for the preparation of ECP, and each metal was combined in a specific and characteristic manner. All the prepared ECPs show excellent thermal stability, and the decomposition temperatures are higher than 347.0 °C (ECP-9) and 418.0 °C (ECP-1), due to the numerous coordination bonds and the network structure of the complex. The sensitivities toward impact and friction were tested using standard methods, and most of ECPs (ECP-1, ECP-2, and ECP-6 to ECP-9) can be considered insensitive to impact and friction, with values higher than 40 J and 360 N, respectively. ECP-3, ECP-4, and ECP-5 are sensitive toward impact (30, 12, and 8 J, respectively), while they are insensitive toward friction (≥360 N). Upon their combustion, these ECPs exhibit a series of unique flame colors, making them promising flame colorants for various ecofriendly pyrotechnic formulations.

Metal Salts of 4-Chloro-3,5-dinitropyrazole for Promising Eco-Friendly Primary Colors Pyrotechnics

“…In our previous work, our group developed a series of new pyrotechnics based on DNPO and DNP (Figure ). , However, during combustion testing, it was found that the characteristic color of DNPO exhibited low purity and poor brightness. To increase the combustion temperature of DNP-based metal salts, we introduced aluminum, while a combustible agent was also added to enhance its combustion efficiency.…”

In situ growth of copper-based energetic complexes on GO and an MXene to synergistically promote the thermal decomposition of ammonium perchlorate

“…6–12 Among them, energetic complexes (ECs) based on the coordination self-assembly of metal ions and nitrogen-rich ligands have the advantages of a high energy level, a large specific surface area and high gas production, thus receiving widespread attention in the field of energetic materials and combustion promoters. 9,13–21…”

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.…”