Energetic–Energetic Cocrystals of Diacetone Diperoxide (DADP): Dramatic and Divergent Sensitivity Modifications via Cocrystallization

Here we report a series of energetic–energetic
cocrystals
that incorporate the primary explosive diacetone diperoxide (DADP)
with a series of trihalotrinitrobenzene explosives: 1:1 DADP/1,3,5-trichloro-2,4,6-trinitrobenzene
(TCTNB), 1:1 DADP/1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB), and
1:1 DADP/1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB). Acetone peroxides
are attractive for their inexpensive and facile synthesis, but undesirable
properties such as poor stability, intractably high sensitivity and
low density, an indicator for low explosive power, have limited their
application. Here through cocrystallization the density, oxygen balance,
and stability of DADP are dramatically improved. Regarding sensitivity,
in the case of the DADP/TCTNB cocrystal, the high impact sensitivity
of DADP is retained by the cocrystal, making it a denser and less
volatile form of DADP that remains viable as a primary explosive.
Conversely, the DADP/TITNB cocrystal features impact sensitivity that
is greatly reduced relative to both pure DADP and pure TITNB, demonstrating
for the first time an energetic cocrystal that is less sensitive to
impact than either of its pure components. This dramatic difference
in cocrystal sensitivities may stem from the significantly different
halogen–peroxide interactions seen in each cocrystal structure.
These results highlight how sensitivity is defined by complex relationships
between inherent bond strengths and solid-state properties, and cocrystal
series such as that presented here provide a powerful experimental
platform to probe this relationship.