Competitive Assembly of π-Hole Interactions and Hydrogen-Bond Networks: Rational Design of Fluorinated Benzotriazole Derivatives as Advanced Low-Melting-Point Energetic Materials

The development of energetic materials that simultaneously achieve low melting points, high energy density, and insensitivity remains a formidable challenge due to inherent conflicts between these properties. Herein, we report a fluorine-modulated molecular design strategy to address this trilemma using benzotriazole-based derivatives. By integrating nitro groups as energy-enhancing units with fluorinated alkyl chains as crystal engineering modifiers, three novel compounds (MBT-1 to MBT-3) were synthesized and systematically characterized. The fluorinated derivative MBT-3 exhibits breakthrough performance: a low melting point (105.3 °C), superior thermal stability (T_d= 300 °C), and insensitivity (IS > 40 J, FS = 324 N, ESD = 7.2 J), while delivering enhanced detonation velocity (6418 m s^–1) and superior crystal density (1.742 g cm^–3) relative to DNAN. MBT-3 emerges as a prime candidate to replace DNAN, offering 7.4% higher detonation velocity and equivalent processability, marking a critical advancement toward safer, high-performance energetic systems. DFT calculations reveal that fluorine substitution in MBT-3 weakens the N–N bond, thereby altering the preferential thermal decomposition pathway from the conventional C-NO₂bond cleavage. Compared with MBT-1, crystallographic analysis reveals that MBT-2 and MBT-3 attenuate nitro π-hole interactions, which consequently directs the formation of different herringbone packing motifs. This electronic-structure-guided modulation establishes a foundational strategy for the directed construction of energetic crystals.