Programming a Metal–Organic Framework toward Excellent Hypergolicity

Abstract

Exploring novel hypergolic fuels for modern space propulsion is highly desired. However, the analysis and understanding of the structure and hypergolic performance at the molecular level are still insufficient. To understand the factors that dictate hypergolicity, we conducted a comparative study on a series of metal–organic frameworks (MOFs) characterized by the same topology but with varied ligand structures. The ignition delay (ID) time trend was found to be imidazole < triazole < tetrazole, and the rapid ID time was 8 ms. By combining experimental studies and density functional theory (DFT) calculations, we found that propargyl and cyanoborohydride groups that functioned as dual hypergolic triggers contributed to the hypergolicity, and a distinct electronic structure was detrimental to ID time. The structure–performance relationships presented herein can potentially provide some fundamental insights into the field of developing high-performance hypergolic fuels.

Coordination polymerization of nitrogen-rich linkers and dicyanamide anions toward energetic coordination polymers with low sensitivities

“…5 The poor activity of 1–4 is probably attributed to the tetrazole ring being an electron-withdrawing group that increases the bandgap. 4 We can detect that 2 displays stable combustion with a high flame height (>25 cm) and long flame duration (1061 ms).…”

“…Energetic materials (EMs) have been widely used in propellants, explosives, and pyrotechnics. [1][2][3][4][5][6][7][8] Excellent EMs should not only have high energy but low sensitivities in consideration of safety. However, the development of EMs always shows that the sensitivities of EMs exponentially increase with the enhancement in their energy.…”

Experimentally Validated Ab Initio Crystal Structure Prediction of Novel Metal–Organic Framework Materials

“…The outstanding rarity of copper­(II)-based materials among ZIFs, combined with the ability of such systems to exhibit hypergolic behavior of potential value in the design of hypergolic propellants, − inspired us to focus on copper­(II)-based ZIFs as suitably novel and challenging targets for this first proof-of-principle application of CSP for MOF discovery.…”

Energetic isostructural metal imidazolate frameworks with a bridging dicyanamide linker towards high-performance hypergolic fuels

“…9,29 (ii) The imidazole-based linkers have the trend of short ID times in contrast with triazoles and tetrazole-based ligands. 30 (iii) Contrary to Cl − , Br − and solvent molecules, the DCA − anions equipped with plenty of N–C and CN bonds can provide a high energy density and exhibit good spontaneous combustion properties in the field of energetic ionic liquids. 31 (iv) The DCA − anions can connect metal atoms to form energetic materials with unique features because of their manifold bridging styles.…”