Comprehensive energetic modifications of peptides for high-performance amphoteric compounds

Abstract

The structural uniqueness and versatile applications of energetic amphoteres have attracted widespread attention. However, their construction has traditionally relied on trial-and-error approaches and continues to lack targeted design strategies and efficient synthesis methods. Herein, leveraging peptides—nature’s paradigmatic amphoteric biomolecules—we developed an integrated energy-optimization strategy encompassing elements, precursors, synthesis, structures, aggregation, and resulting substances to architect a series of energetic amphoteres. Employing direct acid-base condensations, we achieved one-step synthesis of these compounds, exemplified by 2-(hydrazinecarbonyl)-N-nitrohydrazine-1-carboxamide (HNNC, 3b), with 10-gram-scalable production. Meanwhile, HNNC exhibited excellent properties, including high energy (ρ: 1.906 g/cm3; D: 9049 m/s) and high stability (IS: 40 J; Td: 191 oC). Furthermore, HNNC+ and HNNC- salts were synthesized to investigate the effects of proton addition and removal on molecular structures and physicochemical properties: HNNC+ salts exhibited higher energy, while HNNC- salts demonstrated higher stability, and notably, [HNNC+][NO3-] exhibits exceptionally high energy (D: 9462 m/s; P: 37.1 GPa), surpassing that of state-of-the-art FOX-7, RDX, and HMX. In addition, mechanistic insights were obtained through structural deconstruction via site-specific elimination of amino/nitro groups from HNNC, revealing that its high performance results from strong hydrogen bonding. This work provides new insights into the rational design of energetic amphoteres and expands the functional horizons of peptide-inspired materials in energy storage and molecular engineering.