Skeletal Editing of Energetic Materials: Acid-Catalyzed One-Step Synthesis of Bridged Triazoles as High-Energy-Density Materials via the Nef Reaction

Thermally stable insensitive energetic materials have
captivated
significant attention from the global research community due to their
potential impact. In this study, a series of symmetric and asymmetric
nitromethyl-bridged triazole compounds were synthesized from pyrimidine
moieties via a skeletal editing approach. Additionally, carbonyl-bridged
compounds were synthesized in a single step by using acid-catalyzed
Nef reactions from their nitromethyl precursors. Peripheral modifications
of pyrimidine resulted in fused energetic moieties. All synthesized
compounds were fully characterized by using infrared spectroscopy,
high-resolution mass spectrometry, multinuclear magnetic resonance
spectroscopy, elemental analysis, and differential scanning calorimetry.
Single-crystal X-ray diffraction analysis confirmed the structures
of compounds 4 and 10. The newly synthesized
moieties exhibit densities ranging from 1.75 to 1.86 g cm–3, detonation velocities between 8044 and 8608 m s–1, and detonation pressures between 23.10 and 30.31 GPa. Notably,
compounds 9 and 10 demonstrate exceptional
heat resistance, with decomposition temperatures of 315 and 335 °C,
respectively. Computational studies, including density functional
theory, quantum theory of atoms in molecules, noncovalent interactions,
and electrostatic surface potential analysis, account for hydrogen-bonding
and noncovalent interactions. This work highlights the potential of
skeletal editing in the development of high-performing, thermally
stable energetic materials.