Insight into the thermostability and low sensitivity of energetic salts based on planar fused-triazole cation

Article abstract of DOI:10.1016/j.poly.2021.115158

A new family of nitrogen-rich fused-triazole energetic salts based on 3,6-diamino-1H-[1,2,4]triazolo[4,3-b][1,2,4]triazole were synthesized and fully characterized by infrared spectroscopy (IR), ¹H and ¹³C nuclear magnetic resonance, elemental analysis, differential scanning calorimetry (DSC). Structures of 3 and 4·H₂O were confirmed by single-crystal X-ray diffraction analyses and their crystal packing characteristics were thoroughly analysed. All new compounds show good thermal stability (T_d > 223 °C) and tend to be insensitive to external mechanical stimulus. The densities of these salts ranged from 1.72 to 1.93 g cm^?3. Theoretical performance calculations (Gaussian 09 and EXPLO 5) provided detonation pressures and velocities within the ranges of 20.8 to 32.9 GPa and 7599 to 8719 m s^?1, respectively. The perchlorate salt 3 exhibits the highest density (1.93 g cm^?3) and best oxygen balance (?30.0%), good thermal stability (T_d = 258 °C), low sensitivities, and excellent detonation velocity (8719 m s^?1) and pressure (32.9 GPa), which suggest that it has the potential to be used as High-energy–density material.

Full text of DOI:10.1016/j.poly.2021.115158

Polyhedron 201 (2021) 115158
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Insight into the thermostability and low sensitivity of energetic salts
based on planar fused-triazole cation
Chengming Bian a,b, , Qunying Lei , Ji Zhang , Xiang Guo , Zhinan Ma , Haikuan Yang , Hongli Li
Zhongliang Xiao
a
⇑
a
a
c,
⇑
a
a
d,
⇑
,
e
School of Science, North University of China, Taiyuan, Shanxi 030051, PR China
b
CAS Key Laboratory of Energy Regulation Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Lingling Road 345, Shanghai 200032, PR China
Science and Technology on Aerospace Chemical Power Laboratory, Hubei Institute of Aerospace Chemotechnology, Xiangyang 441003, Hubei, PR China
Biochemistry, College of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing 401331, PR China
c
d
e
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A new family of nitrogen-rich fused-triazole energetic salts based on 3,6-diamino-1H-[1,2,4]triazolo[4,3-
Received 15 February 2021
Accepted 10 March 2021
Available online 16 March 2021
b][1,2,4]triazole were synthesized and fully characterized by infrared spectroscopy (IR), 1H and
nuclear magnetic resonance, elemental analysis, differential scanning calorimetry (DSC). Structures of
and 4ꢀH O were confirmed by single-crystal X-ray diffraction analyses and their crystal packing char-
acteristics were thoroughly analysed. All new compounds show good thermal stability (T > 223 °C) and
13
C
3
2
d
Keywords:
tend to be insensitive to external mechanical stimulus. The densities of these salts ranged from 1.72 to
Fused triazoles
Energetic salts
Detonation performance
Stability
ꢁ3
1
.93 g cm . Theoretical performance calculations (Gaussian 09 and EXPLO 5) provided detonation pres-
ꢁ1
sures and velocities within the ranges of 20.8 to 32.9 GPa and 7599 to 8719 m s , respectively. The per-
ꢁ3
chlorate salt 3 exhibits the highest density (1.93 g cm ) and best oxygen balance (ꢁ30.0%), good thermal
ꢁ1
stability (T
d
= 258 °C), low sensitivities, and excellent detonation velocity (8719 m s ) and pressure
(32.9 GPa), which suggest that it has the potential to be used as High-energy–density material.
Ó 2021 Elsevier Ltd. All rights reserved.
1
. Introduction
Five/six-membered heterocycles have widely been employed in
many fused compounds due to their high positive HOF and excel-
lent stability, among which, 1,2,4-triazole is frequently used as a
favorite building block for construction of high-energy–density
materials (HEDMs) [6], such as 2,5-dinitramide-7-amino-[1,2,4]tri-
azolo[1,5-a][1,3,5]triazine [7] and 4-amino-3,7-dinitrotriazolo[5,1-
c][1,2,4]triazine 4-oxide [8]. Developing from monocyclic triazole
to [1,2,4]triazolo[4,3-b][1,2,4]triazole, amino-substituted 1,2,4-tri-
azoles proved to be excellent precursors for cations in energetic
salts attributing to their high thermostability and low sensitivity,
From the traditional explosive TNT (2,4,6-trinitrotoluene) to
energetic salts of pentazolate anion (cyclo-N-
) [1], the development
5
of energetic materials has been a continuously growing research
topic for their academic and practical interests [2]. The design
and synthesis of new nitrogen-rich heterocyclic compounds have
been at the forefront of high-energy research, as they usually pos-
sess green decomposition products and high positive heats of for-
mation (HOF) resulting from the large number of NAC/N single and
double bonds [3]. Moreover, intra-/intermolecular hydrogen bonds
formed in nitrogen-rich compounds would improve the density
and decrease the sensitivity [4].Scheme 1.Scheme 2.
Compared to the non-fused ring analogues, nitrogen-rich fused
heterocyclic compounds recently have attracted great attention
due to the stronger delocalization effect of electron cloud, more
rigid molecular structure and larger ring strain energy, which
should lead to a higher density and superior performance [5].
0
0
0
such as 4,4 ,5,5 -tetraamino-3,3 -bi-1,2,4-triazolium dinitrate
(T = 275 °C, impact sensitivity (IS) = 15 J) [9] and 3,6,7-tri-
amino-7H-[1,2,4]triazolo[5,1-c][1,2,4]triazol-2-ium nitrate
(T = 279 °C, IS = 40 J) [10].
Although 3,6-diamino-1H-[1,2,4]triazolo[4,3-b][1,2,4]triazole
d
d
(2, DATT) has been reported just now [11], the intense interactions
in its salts have barely been studied which are supposed to be the
pivotal feature leading to good thermal stability and low sensitiv-
ity. Our research group had independently obtained DATT and its
salts with higher yields almost at the same time, herein we
reported five other energetic salts based on the planar fused-tria-
zole cation of DATT. All of the compounds were fully characterized
⇑
Corresponding authors.
E-mail addresses: biancm@nuc.edu.cn (C. Bian), guoxiang@casc42.cn (X. Guo),
3
44393820@qq.com (H. Li).
https://doi.org/10.1016/j.poly.2021.115158
277-5387/Ó 2021 Elsevier Ltd. All rights reserved.
0

C. Bian, Q. Lei, J. Zhang et al.
Polyhedron 201 (2021) 115158
NH2
N
NH2
N
2.2. Synthesis
N
H2N
NH
N
H2N
N
N
N
N
Fused-ring
N
N
2.2.1. 3,6-Diamino-1H-[1,2,4]triazolo[4,3-b][1,2,4]triazole (2, DATT)
-Amino-5-hydrazino-l,2,4-triazole dihydrochloride (1) was
N
N
N
N
3
NH2
NH2
NH2
d = 1.712 g cm-3
prepared according to the literature[12]. A solution of 1 (1.87 g,
10 mmol) and cyanogen bromide (1.27 g, 12 mmol) in aqueous
methanol (42 mL, 85%) was refluxed for two days. Methanol was
removed by evaporation, the solid residue was filtered and then
dispersed in proper water. The suspension system was neutralized
by sodium hydroxide and then recrystallized to give light brown
2
, DATT
d = 1.75 g cm
d = 1.725 g cm-3
-3
NH2
H2N
HN
H2N
N
N
N
N
N
N
N
NH
NH2
N
Dicyclic
N
N
NH2
1
H2N
crystals (1.17 g, 84%). H NMR: d = 11.55 (s, 1H), 6.11 (s, 2H),
1
3
d = 1.68 g cm-3
5.55 (s, 2H) ppm.
ESI): 140.15 (M + H) , 281.15 (M + H + MeCN) . IR (KBr pellet):
694, 3414, 3331, 3149, 2785, 1686, 1647, 1617, 1587, 1541,
1490, 1439, 1398, 1356, 1254, 1183, 1133, 1087, 1011, 882, 846,
C NMR: d = 170.25, 155.72, 141.73 ppm. MS
+
+
(
3
NH2
N
N
H2N
NH2
Monocyclic
H2N
NH2
ꢁ1
N
NH
750, 714, 680, 625, 601, 415 cm .Anal. Calcd. (%) For C
3 5 7
H N : C,
N
N
2
5.90; H, 3.62; N, 70.48; found: C, 25.95; H, 3.61; N, 70.43.
d = 1.499 g cm-3
d = 1.658 g cm-3
Scheme 1. Polyamine-triazole nitrogen-rich heterocyclic compounds.
2.2.2. General procedure for synthesis of 3–7
DATT (2 mmol) was dispersed in 40 mL water at room temper-
ature followed by adding one equivalents of free acid (nitric acid
(68%) or perchloric acid(70%)) in one portion. After stirring at
50 °C for 4 h, the solvent was evaporated in vacuo and the residue
was crystallized from water (for 4–7) or ethyl alcohol (for 3).
and their detonation properties were calculated. Structures of 3
2
and 4ꢀH O were confirmed by single-crystal X-ray diffraction anal-
yses and the intense interactions in them were thoroughly
analysed.
2
.2.3. 3,6-Diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium
perchlorate (3)
Colourless crystals (359 mg, 75% yield). H NMR: d = 13.18 (d,
1
2
. Experimental section
1
3
br, 2H), 8.08 (s, 2H), 7.07 (s, 2H) ppm. C NMR: d = 160.15,
148.76, 140.99 ppm. IR (KBr pellet): 1675, 1586, 1566, 1515,
1447, 1404, 1330, 1265, 1145, 1089, 941, 831, 718, 627, 492,
Caution! Although we have not encountered any difficulties in
handling these energetic materials, small scale and best safety
practices (leather gloves and face shield) are strongly encouraged!
ꢁ1
426 cm .Anal. Calcd. (%) For C
3 6 7 4
H ClN O : C, 15.04; H, 2.52; N,
4
0.92; found: C, 14.99; H, 2.61; N, 40.89.
2
.1. General methods
2.2.4. 3,6-Diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium 3-
nitro-5-oxo-1,2,4-triazolate (4)
1H, 13C NMR spectra were recorded at 25 °C on a 600 MHz
Pale brownish-yellow crystals (479 mg, 89% yield). 1H NMR:
d = 12.83 (s, 1H), 6.20 (s, 2H), 5.63 (s, 2H) ppm. 13C NMR:
d = 169.10, 156.06, 154.91, 149.78, 141.63 ppm. IR (KBr pellet):
3561, 3476, 3404, 3209, 1673, 1614, 1548, 1509, 1390, 1356,
1311, 1174, 1052, 1020, 974, 835, 780, 729, 629, 603, 542,
nuclear magnetic resonance spectrometer operating at 600 and
1
TMS for H and C NMR spectra. The solvent was [D
sulfoxide ([D ]DMSO) unless otherwise specified. The melting
and decomposition points were recorded on a differential scanning
calorimetry (DSC) and a Netzsch Sta449F3 equipment at a heating
rate of 5 °C min
rate = 50 mL min ). The infrared spectra were recorded using
KBr pellets. Densities were measured at 25 °C using a Micromerit-
ics Accupyc Ⅱ1340 gas pycnometer. Elemental analyses were
obtained on an Elementar Vario Micro Cube (Germany) elemental
analyzer. The sensitivities to impact (IS) and friction (FS) were
determined according to BAM standards [11].
50 MHz, respectively. Chemical shifts are reported relative to
1
13
6
] dimethyl
6
ꢁ1
419 cm .Anal. Calcd. (%) For C
5 7 11 3
H N O : C, 22.31; H, 2.62; N,
57.24; found: C, 22.37; H, 2.59; N, 57.17.
ꢁ
ꢁ
1
1
in a dynamic nitrogen atmosphere (flow
2.2.5. 3,6-Diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium 4,5-
dinitroimidazolate (5)
1
Yellow solid (552 mg, 93% yield). H NMR: d = 7.76 (s, 2H), 7.21
1
3
(s, 2H) ppm. C NMR: d = 161.65, 149.83, 141.11, 139.75, 139.07,
138.82 ppm. IR (KBr pellet): 3607, 3526, 3400, 3174, 1682, 1657,
1620, 1592, 1536, 1510, 1449, 1352, 1303, 1244, 1179, 1098,
H
H
N
N
N
N
H N
2
N
N
NH
H N
2
NHNH2
·
2HCl 85%MeOH
Energetic Acid
H N
2
N
[Anion]
N
N
N
1
) BrCN
N
NH
2
) NaOH
NH2
NH2
1
2, DATT
3-7
O N
H
2
N
N
N
N
O N
2
O
O N
2
NO2
N
N
NO
2
N
N
N
[Anion]
=
ClO
4
N
NH
N N
O N
2
3
4
5
6
7
Scheme 2. Synthetic route of compounds 2–7.
2

C. Bian, Q. Lei, J. Zhang et al.
Polyhedron 201 (2021) 115158
1
4
5
012, 979, 895, 875, 860, 815, 753, 706, 682, 622, 603, 508,
between triazole and two amino groups (2.78° and 0.60°, respec-
tively) are much smaller than those of 2. The bond lengths of
C1–N6 and C3–N7 are 1.340(3) and 1.320(3) Ǻ, respectively, which
are slightly shorter than those of 2, thus indicate strong conjuga-
tion effect throughout the cation. The lengths of hydrogen bonds
among cations vary from 2.981 Ǻ (N7–H7Aꢀ ꢀ ꢀN4) to 3.465 Ǻ
ꢁ1
24 cm .Anal. Calcd. (%) For C
6 7 11 4
H N O : C, 24.25; H, 2.37; N,
1.84; found: C, 24.27; H, 2.33; N, 51.89.
2.2.6. 3,6-Diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium 3,5-
dinitro-1,2,4-triazolate (6)
1
(N6–H6Bꢀ ꢀ ꢀN3) and are much shorter than those in 4ꢀH O. As
Yellow solid (513 mg, 86% yield). H NMR: d = 13.20 (s, br, 2H),
2
.05 (s, 2H), 7.06 (s, 2H) ppm. 13C NMR: d = 163.29, 160.04, 148.67,
shown in Fig. 1b, strong hydrogen bonds linked to O1 of perchlo-
8
1
1
rate with NAH of cations in the upper layer looks like funnels,
and their lengths lie in the range between 2.363 (N1–H1ꢀ ꢀ ꢀO1)
and 3.069 Ǻ (N7–H7Bꢀ ꢀ ꢀO1). It is critical that O2–O3–O4 in per-
chlorate anions almost lie in the same plane of its paired cations
with a small deviation of 4.02°, thus anions seems to be embedded
in the face-to-face stacking of cations. The strongest hydrogen
bonds are observed between perchlorate and its surrounding
cations in the same layer with the lengths varying from 2.009 Ǻ
to 2.607 Ǻ (Fig. 1c). Attributing to the abundant hydrogen bonds,
the discrete anions and cations are firmly linked into a 3D network.
The layer distance in the compact packing structure consequently
decreased to 3.123 Ǻ and led to the highest density among the
energetic salts of DATT.
40.98 ppm. IR (KBr pellet): 3304, 3164, 1680, 1553, 1500, 1450,
ꢁ
1
394, 1360, 1306, 1116, 1056, 986, 846, 652, 559, 416 cm .Anal.
: C, 20.14; H, 2.03; N, 56.37; found: C,
5 6 12 4
Calcd. (%) For C H N O
2
0.18; H, 2.13; N, 56.32.
2.2.7. 3,6-Diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium 5-
nitriminotetrazolate (7)
1
White solid (452 mg, 84% yield). H NMR: d = 12.86 (s, 2H), 7.85
and 7.07 (d, br, 4H) ppm. 13C NMR: d = 160.70, 157.76, 149.11,
1
1
1
4
41.05 ppm. IR (KBr pellet): 3402, 3348, 3266, 3143, 2671, 1684,
649, 1598, 1544, 1512, 1486, 1445, 1320, 1263, 1241, 1155,
110, 1081, 1037, 1010, 889, 827, 767, 745, 689, 610, 551, 484,
ꢁ1
4 7 13 2
44, 415 cm .Anal. Calcd. (%) For C H N O : C, 17.85; H, 2.62;
Compound 4ꢀH
/c with a calculated density of 1.772 g cm at 167(2) K. The
unit contains one fused-triazole cation, one 3-nitro-5-oxo-1,2,4-
triazolate anion and one H O molecule. The bond lengths of C1–
2
O crystallized in the monoclinic space group
N, 67.64; found: C, 17.92; H, 2.59; N, 67.60.
ꢁ3
P2
1
3
. Results and discussion
2
N6 and C3–N7 are 1.320(3) and 1.329(3) Ǻ, respectively. The dihe-
dral angles between triazole and two amino groups are 1.30° and
In contrast to the literature [11], 85% aqueous methanol was
employed as solvent instead of dilute hydrochloric acid, in which
-amino-5-hydrazino-l,2,4-triazole dihydrochloride (1) reacted
with cyanogen bromide to obtain DATT with a higher yield of
4%. Subsequently, a series of energetic salts (3–7) were prepared
1
.79°, respectively. The cations and anions are approximately par-
3
allel with a dihedral angle of 6.87°. As shown in Fig. 2b, the face-to-
face stacking structure of 4ꢀH
2
O was built up with a layer distance
8
of 3.200 Ǻ.
from the reaction of DATT with the corresponding acid in water. All
new compounds were dried at 60 °C under vacuum for 2 h before
characterization by IR spectroscopy, differential scanning
3
3
.2. Stability
1
13
calorimetry (DSC), H and C NMR spectroscopy and elemental
.2.1. Thermal stability
analysis. The data are listed in the Experimental Section.
The chemical shifts in the 13C NMR spectra of DATT are identi-
Thermal stability is an important property to evaluate the appli-
cation potential of energetic materials. As shown in Table 1, only
perchlorate (3) and 4,5-dinitroimidazolate (5) salts melt prior to
fied at 170.25, 155.72 and 141.73 ppm, and the shifts for its cation
are at around 160.45, 148.89, 141.05 ppm. The signal at
1
decomposition, having T
position temperatures of all new salts which range from 223 °C
5) to 258 °C (3) are lower than that of DATT (277 °C). Thus, ener-
getic salts of DATT exhibit good thermal stabilities which are supe-
rior to that of 1,3,5-trinitro-1,3,5-triazinane (RDX, T = 204 °C).
m
= 244 and 130 °C, respectively. Decom-
d = 11.55 ppm in H NMR spectra of DATT is assigned to the NH
in the fused-triazole backbone, while the rest peaks at 6.11 and
(
5
.55 ppm are attributed to two amino groups. It’s worth noting
that all the signals of the caitons are slightly shifted downfield rel-
ative to those of DATT. The NMR chemical shifts of the anions 4–7
are consistent with those of the previously published ones [6f,10].
d
3
.2.2. Mechanical sensitivity
DATT (2) and its 3-nitro-5-oxo-1,2,4-triazolate salt (4) are
classed as impact and friction insensitive energetic materials
3.1. Crystal structure analysis
(
(
IS > 40 J, FS > 360 N). Salts 3 and 5–7 are insensitive toward impact
IS > 40 J) and their FS values are higher than 216 N. All new com-
The X-ray quality crystal of 3 was obtained by slowly evaporat-
2
ing the ethanol at room temperature while 4ꢀH O was obtained
pounds are much less sensitive than RDX (IS = 7 J, FS = 120 N).
from water. All the crystallographic data in this paper are attached
in the supporting information as well as the reported crystal struc-
tures of DATT (2) and its 3,4,5-trinitropyrazolate salt which have
also been obtained in our study. It’s worth noting that both salt 3
3.3. Intermolecular interaction analysis
and 4ꢀH
2
O show face-to-face stacking structure which are sup-
In order to further insight the causes of good thermal stability
and low sensitivity of these energetic salts, non-covalent interac-
tion (NCI) analysis [13], two-dimensional (2D) fingerprints and
Hirshfeld surfaces analysis [14] of these compounds were
performed.
posed to obtain higher density compared to the crossing stacking
structure of DATT and wave-like stacking structure of 3,4,5-trini-
tropyrazolate salt.
Salt 3 crystallized in the triclinic space group P1 with a calcu-
ꢁ3
lated density of 1.939 g cm at 150(2) K. The salt was formed
by transfer of one proton from perchloric acid to precursor 2 and
synchronous tautomerism of N1 = C2–N5 moiety, thus two hydro-
gen atoms are present at N1 and N4 positions in the cation which
The NCI plots of compound 3 and 4 are shown in Fig. 3. The
face-to-face
p-p interaction surfaces can be distinctly observed
between parallel layers as green isosurfaces. Compared to salt 4
and 3,4,5-trinitropyrazolate salt, the larger isosurfaces in 3 indicate
the more extensive p-p interaction in its packing structure, thus
1
show broad double peaks at around 13.18 ppm in H NMR spectra.
All atoms in the cation are coplanar with the largest torsion angle
greatly improve the stability although perchlorate is usually a sen-
of ꢁ176.4(2)° between N2–N3–C3–N4 while the dihedral angles
sitive anion.
3

C. Bian, Q. Lei, J. Zhang et al.
Polyhedron 201 (2021) 115158
Fig. 1. (a) Crystal structure of compound 3. (b) Packing diagram of 3 viewed towards plane h, k, l = ꢁ275, 51, 370. Only strong hydrogen bonds between O1 of perchlorate and
NAH of cations are represented as blue dotted line for clarity. (c) Hydrogen bonds between perchlorate and its surrounding cations in the same layer.
Fig. 2. (a) Crystal structure of compound 4ꢀH
2
O. (b) Packing diagram of 4ꢀH
2
O viewed towards plane h, k, l = 0, 1, 0. Blue dotted line represents hydrogen bonds between
O molecules in the same
adjacent layersꢀH
2
O molecules are omitted for clarity. (c) Hydrogen bonds between 3-nitro-5-oxo-1,2,4-triazolate and its surrounding cations/H
2
layer.
Table 1
Physical properties and thermochemical values of compounds 2–7.
Comp.
2
3
4
5
6
7
RDX[k]
[
a]
T
T
q
m
(°C)
(°C)
(g cm
(%)
dec
277
244
258
dec
240
130
223
dec
232
dec
dec
204
1.80
37.84
ꢁ21.6
70.3
8795
34.9
7
[
b]
d
244
1.73
67.6
[
c]
ꢁ3
)
1.75
70.5
ꢁ97.7
220.7
7923
20.8
>40
1.93
40.9
ꢁ30.0
122.7
8719
32.9
>40
1.77
57.2
ꢁ62.4
490.9
7912
22.5
>40
1.73
51.8
ꢁ61.9
338.8
7599
21.3
>40
1.72
56.4
ꢁ48.3
401.5
7726
22.1
>40
[
d]
N
OB[ (%)
e]
ꢁ56.5
[
f]
ꢁ1
4
f
H
sal (kJ mol
)
440
[
g]
ꢁ1
v
P
D
(m s
)
7831
21.1
>40
[
h]
(GPa)
[i]
IS (J)
FS (N)
[j]
>360
216
>360
288
288
216
120
[
a] Melting point. [b] Thermal decomposition temperature. [c] Measured density (gas pynometer). [d] Nitrogen content. [e] Oxygen balance. [f] Calculated molar enthalpy of
formation of salts. [g] Detonation pressure. [h] Detonation velocity. [i] Impact sensitivity. [j] Friction sensitivity (BAM friction apparatus). [k] From Ref. [6b].
Fig. 3.
p-
p
Interactions in 3,4,5-trinitropyrazolate salt, 3 and 4 (blue, strong attraction; green, weak interaction; red, strong repulsion).
4

C. Bian, Q. Lei, J. Zhang et al.
Polyhedron 201 (2021) 115158
To better understand their structure-performance, 2D finger-
print plot and Hirshfeld surface were employed to demonstrate
the intermolecular interactions (Fig. 4). The red dots on the Hirsh-
feld surface are attributed to close contacts such Oꢀ ꢀ ꢀH/Hꢀ ꢀ ꢀO and
Nꢀ ꢀ ꢀH/Hꢀ ꢀ ꢀN interactions. As shown in 2D fingerprint plots, these
hydrogen bonds account for more than 60% of the total weak inter-
actions, implying that hydrogen bonds are the primary driven force
to construct these three self-assembled crystals. The blue regions
3.4. Energetic performance
Density is the critical parameter contributing to the perfor-
ꢁ3
mance. DATT has a density of 1.75 g cm , while the densities of
ꢁ3
its salts range from 1.72 (6) to 1.93 (3) g cm . It is noteworthy that
the density of perchlorate salt (3) is much higher than that of RDX
ꢁ
3
ꢁ3
(1.80 g cm ), and falls in the range of HEDMs (1.8–2.0 g cm ). In
addition, salt
3 also possesses the best oxygen balance
on the Hirshfeld surface belong to
C A O and N A O interaction. Consistent with NCI analysis, com-
pound 3 possesses the largest proportion of interaction
19.8%) among three crystals, which would give rise to high density
and low sensitivity especially when cooperated with hydrogen
bonds.
p
-
p
interaction, such as C A N,
(OB = ꢁ30.0%).
Heat of formations were calculated by G4(MP2)-6X method
[15] using the Gaussian 09 (Revision A.02) [16]. DATT has a posi-
p-p
ꢁ1
(
tive HOF of 306.1 kJ mol , whereas its cation possess a much
higher value of 907.0 kJ mol . HOFs of all salts are higher than that
ꢁ1
ꢁ
1
ꢁ1
of RDX (70.3 kJ mol ) and rang from 122.7 (3) to 490.9 kJ mol
4) as computed using the Born–Haber energy cycle.
(
Fig. 4. Hirshfeld surfaces, 2D fingerprint plots and the individual atomic contact percentage contribution of 3,4,5-trinitropyrazolate salt, 3 and 4.
5

C. Bian, Q. Lei, J. Zhang et al.
Polyhedron 201 (2021) 115158
Based on the density and HOF, the detonation pressures (P) and
[2] a) A.K. Chinnam, R.J. Staples, J.M. Shreeve, Org. Lett. 23 (2021) 76–80;
b) D.E. Dosch, M. Reichel, M. Born, T.M. Klapotke, K. Karaghiosoff, Cryst.
Growth Des. 21 (2021) 243–248;
D
velocities (v ) of all compounds were determined using the
EXPLO5 program (Version 6.01) [17]. The detonation velocities
c) L. Zhai, F. Bi, Y. Luo, L. Sun, H. Huo, J. Zhang, J. Zhang, B. Wang, S. Chen, Chem.
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d) Q. Yu, A.K. Chinnam, P. Yin, G.H. Imler, D.A. Parrishc, J.M. Shreeve, J. Mater.
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209–212.
ꢁ1
range from 7599 to 8719 m s and detonation pressure range
from 20.8 to 32.9 GPa, which are superior to traditional military
ꢁ
1
explosive TNT (v
D
= 6881 m s , P = 19.5 GPa). The perchlorate salt
ꢁ1
3
exhibits the best detonation performance (v
P = 32.9 GPa) which is comparable to RDX (v
D
= 8719 m s
= 8795 m sꢁ1,
D
,
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P = 34.9 GPa).
3
4
. Conclusions
(
d) Y. Cao, H. Huang, A. Pang, X. Lin, J. Yang, X. Gong, G. Fan, Chem. Eng. J. 393
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In this work, five energetic salts based on DATT were synthe-
sized and fully characterized. The structures of salts 3 and 4ꢀH
have been analyzed by single-crystal X-ray diffraction analysis.
All these compounds exhibit low sensitivity (IS 40 J,
2
O
114814.
[
[
4] a) Q. Ma, G. Zhang, J. Li, Z. Zhang, H. Lu, L. Liao, G. Fan, F. Nie, Chem. Eng. J. 379
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>
FS ꢂ 216 N) and good thermal stability with decomposition tem-
peratures above 223 °C. The densities of all nitrogen-rich salts lie
ꢁ3
in the range between 1.72 and 1.93 g cm . The calculated detona-
ꢁ1
tion velocities range from 7599 to 8719 m s and detonation pres-
sure range from 20.8 to 32.9 Gpa. According to 2D fingerprint,
Hirshfeld surface and NCI analysis, extensive hydrogen bonds
(
2020) 6084–6092.
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and impactful
p-p interactions lead to low sensitivity (IS > 40 J,
ꢁ3
FS = 216 N) and the highest density (d = 1.93 g cm ) of perchlorate
4
salt 3, thus confirming its excellent detonation performance
d) S. Chen, Y. Liu, Y. Feng, X. Yang, Q. Zhang, Chem. Commun. 56 (2020) 1493–
1496;
e) W. Zhang, H. Xia, R. Yu, J. Zhang, K. Wang, Q. Zhang, Propellants Explos.
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ꢁ1
D
(v = 8719 m s , P = 32.9 GPa) which is comparable to RDX. These
advantages suggest that perchlorate salt 3 may well have promis-
ing applications as high-energy–density materials.
[
4
9 (2020) 368–374;
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Declaration of Competing Interest
(
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared
to influence the work reported in this paper.
d) L. Hu, H. Gao, J.M. Shreeve, J. Mater. Chem. A 8 (2020) 17411–17414;
e) J. Ma, Y. Tang, G. Cheng, G.H. Imler, D.A. Parrish, J.M. Shreeve, Org. Lett. 22
(
2020) 1321–1325;
f) Y. Tang, C. He, G.H. Imler, D.A. Parrishb, J.M. Shreeve, J. Mater. Chem. A. 5
2017) 6100–6105.
7] J. Ma, G. Cheng, X. Ju, Z. Yi, S. Zhu, Z. Zhang, H. Yang, Dalton Trans. 47 (2018)
4483–14490.
(
[
[
[
Acknowledgements
1
8] D.G. Piercey, D.E. Chavez, B.L. Scott, G.H. Imler, D.A. Parrish, Angew. Chem. Int.
Ed. 55 (2016) 15315–15318.
9] T.M. Klapotke, P.C. Schmid, S. Schnell, J. Stierstorfer, J. Mater. Chem. A 3 (2015)
The authors gratefully acknowledge the support of NSFC (No.
2
1602209, 21975066), Open Research Fund Program of Cas Key
2658–2668.
Laboratory Of Energy Regulation Materials (ORFP2020-04), STIP
of Higher Education Institutions in Shanxi (No. 2020L0314), Open
Fund of State Key Laboratory of Deep Buried Target Damage, North
University of China (No. DXMBJJ2020-03), STACPL120201B03.
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[
[
[
8
Appendix A. Supplementary data
1
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Yang, J. Am. Chem. Soc. 132 (2010) 6498–6506;
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[17] M. Su c´ eska, EXPLO5, version 6.01, Brodarski Institute, Zagreb, Croatia, 2013.
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.poly.2021.115158.
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