Trinitromethyl-Functionalized Isoxazole: Achieving the Low Melting Point and Novel Thermal Stability

Low-melting-point energetic compounds, such as trinitrotoluene (TNT) and nitroglycerin (NG), play a crucial role in energetic composites. However, it still remains a great challenge to hunt for promising alternatives due to the multitudinous requirements for practical use. Herein, we reported a new promising molecule, 3-methyl-4-nitro-5-(trinitromethyl) isoxazole (TNMNI, 1) prepared via a simple one-step reaction. The single crystal X-ray structure analysis, Hirshfeld surface, electrostatic potential (ESP), noncovalent interaction (NCI), and LUMO–HOMO molecular orbitals were further investigated to theoretically verify its chemical reactivity, thermostability, and sensitivity. Interestingly, it exhibits a low melting point (Tm: 48.1 °C) and good thermostability (Td: 198.2 °C), which is superior to other high-energy trinitromethyl derivatives. Its calculated detonation velocity and detonation pressure are 8534 m·s–1 and 31.7 GPa, respectively. This work shows significant potential for advancing the development of next-generation energetic plasticizers and melt-castable materials.