Tunable Mechanical Response from a Crystal Undergoing Topochemical Dimerization: Instant Explosion at a Faster Rate and Chemical Storage of a Harvestable Explosion at a Slower Rate

Article abstract of DOI:10.1002/anie.201804589

Strain developed in crystals in response to stimuli causes mechanical response. Methods to tune such mechanical response is important for practical applications. Crystals of a monomer having azide and alkyne units pre-organized in a ready-to-react orientation, undergo thermal topochemical dimerization and show rate-dependent mechanical response. When the reaction rate is fast, the crystals explode violently. When the reaction rate is slow, the crystals absorb water from the surroundings contemporaneously with the reaction to form the dimer-hydrate in a single-crystal-to-single-crystal (SCSC) manner. Crystals of the dimer-hydrate upon dehydration also undergo explosion. Thus, at slow reaction rate, the strain gets stored in crystals by hydration and the explosion can be harvested, at will, by dehydration. Use of this rate-dependent explosion in the automatic activation of a remedial electrical circuit in case of a sudden rise in temperature has been demonstrated.

Full text of DOI:10.1002/anie.201804589

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Tunable Mechanical Response from a Crystal Undergoing
Topochemical Dimerization: Instant Explosion at Faster Rate and
Chemical Storage of 'Harvestable Explosion' at Slower Rate
Authors: Kana M Sureshan and Arthi Ravi
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201804589
Angew. Chem. 10.1002/ange.201804589
Link to VoR: http://dx.doi.org/10.1002/anie.201804589
http://dx.doi.org/10.1002/ange.201804589

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
Tunable Mechanical Response from a Crystal Undergoing
Topochemical Dimerization: Instant Explosion at Faster Rate and
Chemical Storage of ‘Harvestable Explosion’ at Slower Rate
Arthi Ravi and Kana M. Sureshan*
Dedicated to Prof. K. N. Ganesh on his 65th birthday
Abstract: Strain developed in crystals in response to stimuli, causes
mechanical response. Methods to tune such mechanical response is
important for practical applications. Here we report that crystals of
monomer 1, having azide and alkyne units pre-organized in a ready-
to-react orientation, undergo thermal topochemical dimerization to
dimer 2 and show rate-dependent mechanical response. When the
reaction rate is fast, the crystals explode violently. When the reaction
rate is slow, the crystals absorb water from the surroundings
contemporaneously with the reaction to form the dimer-hydrate in a
single-crystal-to-single-crystal (SCSC) manner. Crystals of dimer-
hydrate upon dehydration also undergo explosion. Thus, at slow
reaction rate, the strain gets stored in crystals by hydration and the
explosion can be harvested, at will, by dehydration. Use of this rate-
dependent explosion in the automatic activation of a remedial
electrical circuit in case of sudden rise in temperature has been
demonstrated.
single-crystal-to-single-crystal (SCSC) pathway and releases
this stored strain later upon dehydration.
Figure 1. a) Chemical structure and b) ORTEP diagram of compound 1. The
thermal ellipsoids are at 30% probability. c) Head-to-tail centrosymmetric non-
covalent dimer of compound 1 showing the juxtaposed azide and alkyne
motifs. The reacting motifs are highlighted as ball and stick.
Materials that respond to various stimuli are of great interest in
view of their possible applications in electronics, sensing, smart
materials etc.[1] There is a growing interest in stimuli responsive
crystals recently. Crystals respond to stimuli viz. light, heat,
pressure etc.[2] primarily by molecular processes such as
polymorphic transition,[3] chemical reaction,[4] isomerization,[5] or
conformational change to form daughter-phase. The growth of
daughter-phase in the parent-phase develops strain in the
crystal,[2a,6] and to release this strain, such crystals show some
macroscopic mechanical response[2a] in addition to the basic
molecular processes. While elastic crystals release the strain as
and when developed by slow and continuous mechanical
reconfiguration such as bending,[4g-i,7] twisting,[4e-h] curling,[5b]
rolling,[4i] change of size and shape[8] etc., plastic crystals, on the
other hand, build up the strain to a critical level and then
suddenly release by jumping, exploding, cracking etc.[3b-c,4a-c,9] In
either case, the stimuli-induced strain-energy cannot be stored
in the crystal for longer durations. A remarkable advancement in
this area would be to store the strain energy in the single crystal
itself for future harvest of the mechanical response at will. Here
we report a topochemically-reactive crystal that, at faster
reaction-rate, releases the developed strain instantly by
explosion and, at slower rate, store the strain by absorbing water
from the surroundings contemporaneously with the reaction in a
Monomers decorated with azide and alkyne groups can
give triazole-linked polymers via Cu(I)-catalyzed click reaction.[10]
There are also a few reports that they can undergo uncatalyzed
polymerization via proximity-driven cycloaddition reaction in solid
state.[11,4e] We have synthesized the monomer 1 (Supporting
Information) having azide and alkyne groups (Figure 1a) and
crystallized from 1:1 ethyl acetate/hexane mixture (Figure 1b,
Table S1). Crystal structure of compound 1, determined by
Single-Crystal X-ray Diffraction (SCXRD) revealed that the
molecules form a head-to-tail centrosymmetric supramolecular
dimer through weak C-H…N hydrogen bond (Figure S1).
Several other interactions stabilize such a packing (Table S2).
The reaction partners in the dimer are juxtaposed parallelly as in
the transition state for their cycloaddition reaction. The distances
between the termini of azide and alkyne moieties (4.0 Å and 3.6
Å) are apt for their topochemical cycloaddition reaction (Figure
1c).[12] Crystals of compound 1 are stable at room temperature
for several months. But at temperatures above 50 oC, the
crystals react to form the1,5-triazolyl linked cyclic dimer 2
(Supporting Information Section 3) as the only product, as a
result of regiospecific 1,3-dipolar cycloaddition between azide
and alkyne as expected from the crystal structure of compound
1. The progress of the reaction was followed using time-
dependent 1H NMR, IR, DSC and PXRD techniques by
withdrawing small portions of the heated sample at different time
intervals and these experiments revealed that the dimerization
reaction happens under topochemical control (Supporting
Information Section 6, Figure S2).
[a]
A. Ravi, Prof. Dr. K. M. Sureshan
School of Chemistry, Indian Institute of Science Education and
Research Thiruvananthapuram, Vithura – 695551 (India)
E-mail: kms@iisertvm.ac.in
Supporting
information
can
be
found
under
It was observed that the crystals of monomer 1 do not melt
https://doi.org/10.10xxx. CCDC 1829360-1829362 contain the
supplementary crystallographic data for this paper. These data are
provided free of charge by The Cambridge Crystallographic Data
Centre.
o
even at very high temperature (300 C) but interestingly explode
o
at around 190 C. To investigate this further, we have heated
several crystals of 1 on a hot-stage microscope at a heating rate
This article is protected by copyright. All rights reserved.

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
of 5 oC/min. All the crystals exploded, and the debris scattered
all around (Movie S1). 1H NMR spectroscopy and HRMS
analysis of the debris formed after the explosion showed that it
contains only dimer 2 (Figure S3). This implies that the
explosion happens after the complete dimerization reaction.
was cooled and then analyzed by single crystal X-ray diffraction.
The crystal contained both the dimer 2 (66%) and the monomer
1 (34%). The crystal structure of this partially reacted crystal
suggests that the dimerization happens in a single-crystal-to-
single-crystal manner even at high temperature (Figure 2e).
Though the space group remained unchanged (P21/c), the unit
cell dimensions changed due to the reaction. While the unit cell
parameter ‘a’ expanded by 2.8%, ‘b’ and ‘c’ contracted by 2%
and 2.5% respectively (Table S1) and resulted in an overall
reduction of volume by 1.8%. Clearly, the macroscopic changes
in the crystal dimensions arise from these changes in unit cell
dimensions.
Figure 2. a) Optical microscopy images of a single crystal heated at 5 oC/min
at various stages. b) Plot of change in dimensions of crystal of monomer 1
with temperature. c) DSC thermogram of monomer 1 (rate of heating is 5
oC/min). d) Chemical structure of dimer 2. e) ORTEP diagram of partially
reacted monomer showing the fragments of both monomer and dimer. The
thermal ellipsoids are at 20% probability.
Figure 3. a) BFDH morphology of monomer 1 and partially reacted crystal. b)
Face-indexing of single crystal of monomer 1 with the respective faces
assigned. c) Schematic representation of single crystal of monomer
expanding along a-direction and contracting along the b- and c-directions.
1
The Bravais-Friedel-Donnay-Harker (BFDH) morphology of
the crystal of monomer 1 and partially reacted crystal were
determined from the diffraction data (Figure 3a). Face-indexing
of a few single crystals of monomer 1 were carried out to identify
various faces of the crystals (Figure 3b). To correlate the
molecular-level changes with the macroscopic change, the faces
determined from crystal structure morphology were matched
with that of face-indexed crystals. This comparison revealed that
the cycloaddition between juxtaposed azide-alkyne moieties
occur along c- and b-axes (corresponding to breadth and
thickness of the crystal), and the monomer molecules must
move closer to achieve the reaction (Figure 3). This accounts for
the shrinking of crystal along the breadth and height, during
product formation. As no reaction occurs along the length of the
crystal (a-direction) and the intermolecular interactions are weak
along this direction (Figure S5), the crystal undergoes elongation
to compensate for the contraction along breadth and thickness
(to avoid large change in the volume).
It was found that the crystals change their dimensions prior
to bursting (Figure 2a). A plot of % change in dimensions
against temperature revealed that, at all heating rates, the length
of the crystal increased, and the breadth of the crystal
decreased gradually and an abrupt change in dimension was
observed just before the explosion (Figure 3b, Figure S4). The
o
temperature (175 C) at which this sudden dimensional-change
happens coincided with the temperature at which the maximum
topochemical reaction occurs. DSC profile of crystals of 1, at a
o
heating rate of 5 C/min, suggested that the maximum reaction
happens at 175 oC (Figure 2c). This suggests that the change in
crystal dimensions may be due to the topochemical reaction.
To understand the molecular level changes responsible for
this macroscopic change, crystal structure of a single crystal
was solved by SCXRD at its elongated stage just before
explosion. For this, a single crystal of compound 1 was heated
at a heating rate of 5 oC/min under a hot stage optical
o
microscope. When the temperature reached 190 C, maximum
change in crystal dimensions was observed and at this point it
This article is protected by copyright. All rights reserved.

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
Figure 4. a) ORTEP diagram of dimer 2.H2O. The thermal ellipsoids are at 30% probability. b) Packing arrangement of monomer 1 stabilized by C-H…O and C-
H…N hydrogen bonds. c) Packing arrangement of dimer 2.H2O in the ‘bc’ plane stabilized by weak (C-H…O and C-H…N) and strong (O-H…O & O-H…N)
hydrogen bonding; Dimer molecules are bridged by water molecules and due to this the dimer 2.H2O is stabilized by more number of interactions compared to the
monomer. d) TGA analyses of dimer formed under slow and fast heating rate. The dimer formed under slow heating rate shows a weight loss of 1.5% starting at
178 oC. e) Comparison of PXRD spectra of the dimer formed under slow and fast heating. f) Moisture dictates! Snapshots of the monomer crystals heated at 90
oC for 6 days in (i) dry (inert) condition; the crystals of monomer 1 convert to dimer 2 but crumble to powder. (ii) open (humid) condition; the crystals of monomer 1
convert to dimer 2.H2O in a SCSC manner.
In order to see whether we can control the mechanical
response and get fully reacted single-crystal, the rate of the
reaction was slowed down by keeping the crystals of 1 at a
constant temperature of 90 oC. The reaction was complete in
132 h. To our delight, the single crystals were intact even after
complete reaction. We have solved the crystal structure of one
of these crystals by using SCXRD analysis. It is gratifying to
six other dimer molecules arranged in a hexagonal arrangement
(Figure 4c). Several weak CH…O and CH…N H-bonds also
stabilize such connectivity (Table S2). Along “a” axis, dimer
molecules are connected through weak van der Waal
interactions (Figure S5).
From the crystal structure, it is clear that the water
molecule stabilizes the crystal of the dimer 2. TGA of 2.H2O
revealed that the water molecules escape from the crystal only
note that the topochemical dimerization of monomer
1
o
proceeded quantitatively in a SCSC fashion with preservation of
the space group (Table S1). In addition to the dimer 2, one water
molecule per dimer was also found in the crystal lattice (Figure
4a). Each water molecule is tetrahedrally coordinated to four
molecules of dimer 2 through OH…N, OH…O and CH…O
hydrogen bonds (Figure S5, Figure 4c). In ‘bc’ plane each dimer
2 molecule is non-covalently bridged through water molecules to
at very high temperature of 178-294 C (Figure 4d). This is not
surprising as each water molecule is connected to four dimer
molecules through two hydrogen bonds and two CH…O H-
bonds (Figure 4c, Table S2). A comparison of PXRD profiles of
the debris formed via explosion of crystals under fast heating
rate and the single crystals formed via SCSC transition under
slow heating rate revealed that the packing of these two crystals
This article is protected by copyright. All rights reserved.

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
are different (Figure 4e). TGA of the debris formed after
explosion of the crystal, under fast heating rate (5 oC/min),
proved the absence of water in them (Figure 4d).
(Figure 5). In the experimental setup, one of the terminals is
connected to a conducting plate, on which a single crystal was
placed, and the other terminal was placed above the crystal. As
the insulator crystal separates the electrodes, at ambient
temperature the circuit is in ‘OFF’ state. However, upon heating
the plate, the crystal exploded, and the circuit was switched ‘ON’
(Movie S3).
In order to check the role of water in the SCSC nature of
the reaction, crystals of 1 was heated in a dry atmosphere (glove
box) at 90 oC, the same temperature at which the reaction
followed an SCSC pathway in an open atmosphere, and
regularly monitored by 1H NMR as before. The reaction
proceeded as expected and at the same rate as the reaction in
an open atmosphere of relative humidity 50%. However, the
crystal gradually lost its transparency and slowly crumbled into a
heap of powder at the end of 132 h (Figure 4f). Thus, the
reaction under open atmosphere follows a SCSC pathway (vide
supra), but under dry conditions the reaction leads to the loss of
crystal-integrity. This clearly establishes that water is essential
for the reaction to proceed in a SCSC fashion.
A comparison of the crystal structures of monomer 1 and
dimer 2 reveals that the monomer molecules in the non-covalent
centrosymmetric dimer move closer by approximately 1Å during
the reaction (Supporting Information Section 9, Figure S6) and
this generates free space (cavity) in the crystal lattice (Figure
S6). Crystals in general prefer close packing [13] and the empty
volume generated as a result of the reaction causes strain in the
crystals. In addition, the heat liberated due to the exothermic
reaction contributes to the overall strain. The fate of the reacting
crystal depends on the rate of the reaction (heating rate). When
the rate of the reaction is fast, huge strain is generated rapidly
and to relax this strain, the crystal undergoes sudden
dimensional change (shrinking along its breadth and thickness
and consequent elongation) to such an extent that the crystal
cannot retain its structural integrity and hence undergoes
explosion. When the rate of the reaction is sufficiently slow, the
free space (and hence the strain) is created slowly and this
would allow gradual absorption of water from the surroundings
to fill these cavities contemporaneously with the reaction to form
a stable stoichiometric hydrate in a SCSC fashion till the end of
the reaction. In this case, as the rate of strain development is
slow, the crystal is stabilized through slow hydration.
It is clear that without water, the crystal of 2 is unstable
(strained) and hence explodes. We were curious to see whether
the removal of water from crystals of 2.H2O will regenerate the
strain in the crystal and thus show mechanical response. To
investigate this, we have heated a few crystals of 2.H2O on a
hot-stage microscope at heating rate of 5 oC/min (Movie S2). We
found that when the temperature reached around 180 oC, the
crystal exploded. It is to be recalled that TGA at this heating rate
suggested that the dehydration occurs at this temperature
(Figure 4d). Thus, it is clear that when water is removed, the
crystals regain the strain and undergo explosion. This is the first
case showing that the strain generated in a crystal due to a
stimulus can be stored in the crystal itself and can be harvested
as and when required. Controlling the mechanical response by
modulating the external stimuli is of great significance.[14]
Figure 5. a) and b) Schematic representation of the electrical circuit in which
crystals of compound 1 were used as a switch; c) Photograph of the electrical
circuit.
In conclusion, we reported a thermal dimerization of a
monomer, having azide and alkyne groups, to its cyclic dimer via
dipolar cycloaddition reaction. The ready-to-dimerize pre-
organized arrangement of monomer molecules facilitates
regiospecific topochemical dimerization in the crystal. Though
the dimerization reaction proceeds topochemically at all heating
rates, the rate of the reaction dictates the fate of the reacting
crystal. When the rate is fast, the crystal explodes violently due
to the sudden increase in the strain and when the rate is slow
the reaction follows a silent SCSC pathway by absorbing water
molecules from surroundings forming a hydrate. By this hydrate
formation, the strain developed slowly due to the slow
topochemical reaction is stored in the crystal itself and up on
dehydration, these hydrated crystals exhibit violent explosion.
Apart from this interesting storage of stimuli-induced strain and
its possible harvest at will, the heating rate-dependent explosion
might find application in the design of turn on switches for
activation of remedial electrical circuit without human
intervention in case of sudden rise in temperature.
Acknowledgements
K.M.S. thanks Department of Science and Technology for a
SwarnaJayanti Fellowship (DST/SJF/CS02/2012-13)
Keywords: cycloaddition • dimerization • exploding crystals •
mechanical response • electrical switch
We envisioned the utility of such heating-rate dependent
exploding-crystals for the activation of remedial electrical circuits
in an unmanned mission or machinery in case of a sudden rise
in temperature. To demonstrate such a practical application, we
made an electrical circuit comprising of a DC power source, an
LED strip as the load and a single crystal of 1 as the switch
[1]
a) C. J. Kloxin, C. N. Bowman, Chem. Soc. Rev. 2013, 42, 7161; b) R.
Verduzco, Science 2015, 347, 949; c) S. Iamsaard, S. J. Aßhoff, B.
This article is protected by copyright. All rights reserved.

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
Matt, T. Kudernac, J. J. L. M. Cornelissen, S. P. Fletcher, N. Katsonis,
[5]
a) O. S. Bushuyev, A. Tomberg, T. Friščić, C. J. Barrett, J. Am. Chem.
Soc. 2013, 135, 12556; b) T. Kim, M. K. Al-Muhanna, S. D. Al-
Suwaidan, R. O. Al-Kaysi, C. J. Bardeen, Angew. Chem. Int. Ed. 2013,
52, 6889; Angew. Chem. 2013, 125, 7027.
Nat. Chem. 2014, 6, 229.
[2]
[3]
a) P. Naumov, S. Chizhik, M. K. Panda, N. K. Nath, E. Boldyreva,
Chem. Rev. 2015, 115, 12440; b) N. K. Nath, M. K. Panda, S. C. Sahoo,
P. Naumov, CrystEngComm 2014, 16, 1850; c) O. Sato, Nat. Chem.
2016, 8, 644; d) G. R. Krishna, R. Devarapalli, G. Lal, C. M. Reddy, J.
Am. Chem. Soc. 2017, 138, 13561; e) S. Saha, G. R. Desiraju, J. Am.
Chem. Soc. 2017, 139, 1975.
[6]
[7]
P. Commins, I. T. Desta, D. P. Karothu, M. K. Panda, P. Naumov,
Chem. Commun. 2016, 52, 13941.
a) S. H. Mir, Y. Takasaki, E. R. Engel, S. Takamizawa, Angew. Chem.
Int. Ed. 2017, 56, 15882; Angew. Chem. 2017, 129,16098; b) A. Worthy,
A. Grosjean, M. C. Pfrunder, Y. Xu, C. Yan, G. Edwards, J. K. Clegg, J.
C. McMurtrie, Nat. Chem. 2018, 10, 65.
a) Z. S. Yao, M. Mito, T. Kamachi, Y. Shiota, K. Yoshizawa, N. Azuma,
Y. Miyazaki, K. Takahashi, K. Zhang, T. Nakanishi, S. Kang, S.
Kanegawa, O. Sato, Nat. Chem. 2014, 6, 1079; b) S. C. Sahoo, S. B.
Sinha, M. S. R. N. Kiran, U. Ramamurty, A. F. Dericioglu, C. M. Reddy,
P. Naumov, J. Am. Chem. Soc. 2013, 135, 13843; c) M. K. Panda, R.
Centore, M. Causà, A. Tuzi, F. Borbone, P. Naumov, Sci. Rep. 2016, 6,
29610.
[8]
[9]
a) M. Irie, S. Kobatake, M. Horichi, Science 2001, 291, 1769; b) K.-J.
Chen, Y.-C. Tsai, Y. Suzaki, K. Osakada, A. Miura, M. Horie, Nat.
Commun. 2016, 7, 13321.
a) R. Medishetty, S. C. Sahoo, C. Mulijanto, P. Naumov, J. J. Vittal,
Chem. Mater. 2015, 27, 1821; b) M. K. Panda, T. Runcevski, A. Husain,
R. E. Dinnebier, P. Naumov, J. Am. Chem. Soc. 2015, 137, 1895; c) S.
Ghosh, M. K. Mishra, S. Ganguly, G. R. Desiraju, J. Am. Chem. Soc.
2015, 137, 9912; d) D. Kitagawa, T. Okuyama, R. Tanaka, S. Kobatake
Chem. Mater. 2016, 28, 4889.
[4]
a) A. Natarajan, C. K. Tsai, S. I. Khan, P. McCarren, K. N. Houk, M. A.
Garcia-Garibay, J. Am. Chem. Soc. 2007, 129, 9846; b) R. Medishetty,
A. Husain, Z. Bai, T. Runčevski, R. E. Dinnebier, P. Naumov, J. J. Vittal,
Angew. Chem. Int. Ed. 2014, 53, 5907; Angew. Chem. 2014, 126,
6017; c) E. Hatano, M. Morimoto, T. Imai, K. Hyodo, A. Fujimoto, R.
Nishimura, A. Sekine, N. Yasuda, S. Yokojima, S. Nakamura, K. Uchida,
Angew. Chem. Int. Ed. 2017, 56, 12576; Angew. Chem. 2017, 129,
12750; d) S. Kobatake, S. Takami, H. Muto, T. Ishikawa, M. Irie, Nature
2007, 446, 778; e) R. Rai, B. P. Krishnan, K. M. Sureshan, Proc. Natl.
Acad. Sci. U.S.A. 2018, 115, 2896; f) D. Kitagawa, H. Tsujioka, F. Tong,
X. Dong, C. J. Bardeen, S. Kobatake, J. Am. Chem. Soc. 2018, 140,
4208; g) T. Kim, L. Zhu, L. J. Mueller, C. J. Bardeen, J. Am. Chem. Soc.
2014, 136, 6617; h) L. Zhu, R. O. Al-Kaysi, C. J. Bardeen, Angew.
Chem. Int. Ed. 2016, 55, 7073; Angew. Chem. 2016, 128, 7189; i) H.
Wang, P. Chen, Z. Wu, J. Zhao, J. Sun, R. Lu, R. Angew. Chem. Int.
Ed. 2017, 56, 9463; Angew. Chem. 2017, 129, 9591.
[10] a) Y. Chen, Z. Guan, J. Am. Chem. Soc. 2010, 132, 4577; b) S. Hartwig,
S. Hecht S. Macromolecules 2010, 43, 242.
[11] a) W. Li, X. Li, W. Zhu, C. Li, D. Xu, Y. Ju, G. Li, Chem. Commun. 2011,
47, 7728; b) B. P. Krishnan, R. Rai, A. Asokan, K. M. Sureshan, J. Am.
Chem. Soc. 2016, 138, 14824; c) Pathigoolla, A.; Sureshan, K. M.
Angew. Chem. Int. Ed. 2014, 53, 9522; Angew. Chem. 2014, 126, 9676.
[12] G. M. J. Schmidt, Pure. Appl. Chem. 1971, 27, 647.
[13] I. Hargittai, Struct. Chem. 2014, 25, 1321.
[14] A. A. Matvienko, D. V. Maslennikov, B. A. Zakharov, A. A. Sidelnikov, S.
A. Chizhik, E. V. Boldyreva, IUCrJ 2017, 4, 588.
This article is protected by copyright. All rights reserved.

10.1002/anie.201804589
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Crystals of an azide-and-alkyne
functionalized cyclitol derivative
undergo topochemical azide-alkyne
cycloaddition reaction to form its
cyclic dimer. When the reaction-rate
is faster, the crystals explode and
when it is slower, the crystal absorb
water from the surroundings to form
Arthi Ravi, Kana M. Sureshan*
Page No. – Page No.
Tunable Mechanical Response
from a Crystal Undergoing
Topochemical Dimerization:
Instant Explosion at Faster Rate
and Chemical Storage of
‘Harvestable Explosion’ at Slower
Rate
the hydrated-dimer in
crystal-to-single-crystal
a
single-
manner,
which upon dehydration explodes
violently. Thus, hydration stores the
strain and dehydration releases it.
This article is protected by copyright. All rights reserved.