Dihydrogen Bond Cooperativity Resolves Zero-Linear Compressibility in an Energetic Crystal

Zero linear compressibility (ZLC) energetic materials can be used as anti-shock materials to maintain stability in at high-pressure environments up to tens of gigapascals under shock conditions. Achieving an energetic material with ZLC properties and clarifying its structure-activity relationship should meet the urgent safety demands. In this study, the first ZLC organic molecular crystal, trimethylamine borane (TMAB), which can be utilized as a propellant component, was discovered. TMAB underwent an isostructural phase transition at 9.2 GPa, as evidenced by the combination of Raman, infrared, and UV-vis absorption spectra and in situ synchrotron x-ray diffraction patterns. Note that the c axis exhibited intriguing ZLC in the pressure range from 9.2 to 14.0 GPa, indicating the superior stability of TMAB under extreme high pressure. The dihydrogen-bonding cooperativity effect under high pressure was responsible for the observed ZLC in TMAB, unlike that observed for previously reported ZLC materials. This study developed a ZLC energetic organic molecular crystal and revealed its underlying mechanism, which facilitates the design of anti-shock propellants.