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Updated: Jun 2, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Intramolecular Cyclization and Energetic Group Modifications for Thermally Stable and Low-Sensitivity Monocyclic
Changlin Zhou1,2, Qingshan Xie1, Junqi Wang1
1College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, China Three Gorges University, Yichang 443002, China.
Abstract:
Zwitterionic energetic materials offer a unique combination of high performance and stability, yet their synthesis and stability enhancement remain key challenges. In this study, we report the synthesis of a highly stable (dinitromethyl-functionalized zwitterionic compound, 1-(amino(iminio)methyl)-4,5-dihydro-1H-pyrazol-5-yl)dinitromethanide (4), with a thermal decomposition temperature of 215 °C, surpassing that of most previously reported energetic monocyclic zwitterions (Td < 150 °C). This compound was synthesized via intramolecular cyclization of a trinitromethyl-functionalized hydrazone precursor. Further chemical modifications, including nitration and fluorination, enabled zwitterion-to-zwitterion transformations, resulting in the formation of nitramines 10 and 12. Additionally, the perchlorate salt (8) of 4 was synthesized, along with ammonium (13), guanidinium (14), and potassium (15) salts derived from 10, all retaining zwitterionic properties. Physicochemical evaluations reveal that zwitterion 12 exhibits excellent thermal stability (Td = 181 °C) and an optimal balance between high energy output (detonation velocity: 8329 m s-1, detonation pressure: 29.4 GPa) and reduced sensitivity (impact sensitivity: 35 J, friction sensitivity: 320 N). Notably, potassium salt 15 demonstrates superior thermal stability (Td = 233 °C), exceeding that of RDX. These results expand the design framework for energetic zwitterions and contribute to the development of high-energy, low-sensitivity energetic materials.
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