Design and Synthesis of a Series of Nitrogen-Rich Energetic Cocrystals of 5,5′-Dinitro‑2<i>H</i>,2<i>H</i>′‑3,3′-bi-1,2,4-triazole (DNBT)

A series of three energetic cocrystals containing 5,5′-dinitro-<i>2H</i>,2<i>H</i>′-3,3′-bi-1,2,4-triazole (DNBT) were obtained. These incorporate a class of energetic materials that has seen significant synthetic work, the azole family (tetrazoles, triazole, pyrazole, etc.), and yet have struggled to see broad application. A cocrystal was obtained with the triazole 5-amino-3-nitro-1<i>H</i>-1,2,4-triazole (ANTA) in a stoichiometry of 2:1 (ANTA:DNBT). Two cocrystals were obtained with the pyrazoles 1<i>H</i>,4<i>H</i>-3,6-dinitropyrazolo­[4,3-<i>c</i>]­pyrazole (DNPP) and 3,4-dinitropyrazole (3,4-DNP) in ratios of 1:1 (DNPP:DNBT) and 2:1 (3,4-DNP:DNBT). All three cocrystals, 2:1 ANTA/DNBT (<b>1</b>), 1:1 DNPP/DNBT (<b>2</b>), and 2:1 3,4-DNP/DNBT (<b>3</b>), have high densities (>1.800 g/cm³) and high predicted detonation velocities (>8000 m/s). In small-scale impact drop tests, cocrystals <b>1</b> and <b>2</b> were both found to be insensitive, whereas cocrystal <b>3</b> possesses sensitivity between that of its two pure components 3,4-DNP and DNBT. The hydrogen bonding motif of the three components with DNBT is preserved among all three cocrystals, and this observation suggests a generally useful motif to be employed in the development of other energetic–energetic cocrystals. These cocrystals represent an area of energetic materials that has yet to be explored for cocrystalline materials