Pillararene-Based Two-Component Thixotropic Supramolecular Organogels: Complementarity and Multivalency as Prominent Motifs

Article abstract of DOI:10.1002/chem.201801418

Rationally designed two-component supramolecular organogels based on multiple chemical interactions between percarboxylato- and peramino-pillararenes are described. Mixing low concentration solutions (<1 % w/v) of decacarboxylato-pillar[5]arene (1) with decaamino-pillar[5]arenes (2 b–d) affords, rapidly and without heating, organogels displaying an exceptional combination of properties. These supramolecular organogels, the characteristics of which are tunable, were found to be thixotropic and thermally stable, with T_gel values in some cases exceeding the boiling point of the embedded solvent. It is demonstrated that both structural complementarity and multivalency are important determinants in the gelation process of these attractive soft materials.

Full text of DOI:10.1002/chem.201801418

A Journal of
Accepted Article
Title: Pillararene-based Two-Component Thixotropic Supramolecular
Organogels: Complementarity and Multivalency as Prominent
Motifs
Authors: Yoram Cohen, Yossi Zafrani, Dana Kaizerman, Maya Hadar,
Nitzan Bigan, Eran Granot, Moumita Ghosh, Lihi Alder-
Abramovich, and Fernando Patolsky
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To be cited as: Chem. Eur. J. 10.1002/chem.201801418
Link to VoR: http://dx.doi.org/10.1002/chem.201801418
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Pillararene-based Two-Component Thixotropic Supramolecular
Organogels: Complementarity and Multivalency as Prominent
Motifs
Yossi Zafrani,*[a,b] Dana Kaizerman,[a] Maya Hadar,[a] Nitzan Bigan,[a] Eran Granot, [a] Moumita Ghosh,[c]
Lihi Adler-Abramovich,[c] Fernando Patolsky,[a] and Yoram Cohen*[a].
self-assembled supramolecular systems, such as organic
nanotubes,[11] capsules,[12]
molecular supramolecular
Abstract: Rational designed two-component supramolecular
organogels based on multiple chemical interactions between
percarboxylato- and peramino-pillararenes are described. Mixing low
concentration solutions (<1% w/v) of decacarboxylato-pillar[5]arene
(1) with decaamino-pillar[5]arenes (2b-d) affords, rapidly and without
heating, organogels displaying exceptional combination of properties.
These supramolecular organogels, which characteristics are tunable,
were found to be thixotropic and thermally-stable with Tgel values in
some cases, exceeding the boiling point of the embedded solvent.
We demonstrate that both structural complementarity and
multivalency are important determinants in the gelation process of
these attractive soft materials.
polymers,[13] and more. In the last decade, pillar[n]arenes,[14a]
which provide the opportunity of anchoring a plurality of
functional groups on both sides of a relatively rigid molecular
framework, have emerged into an important building block in the
field of supramolecular chemistry.[14] This occurred since
pillararenes are easy-to-prepare, and molecular manipulations at
both rims of these symmetric macrocycles is straightforward.
This enables one to easily prepare organic and water soluble-
pillararenes with different functionalities.[14-15] Recently, we
became interested in the synthesis and applications of water
soluble pillar[n]arenes, and explored their potential as anti-
biofilm agents,[16a,b] and 129Xe-NMR biosensors.[16c] Based on the
structural characteristics of pillararenes, we hypothesized that
the interactions between percarboxylato- and peramino-
pillararenes may produce supramolecular architectures, such as
organic nanotubes, via multiple attractive electrostatic forces
associated to hydrogen bond which in turn may provide 3D
networks. Figure 1 presents the structures of the percarboxylato-
and peramino-pillararenes, and some of the modular variety that
can be obtained by their molecular modifications.
Supramolecular organogels are attracting much interest in
recent years as soft matters, since their properties can be easily
tuned by structural modification of their low-molecular-mass
organic gelator (LMOG) units.[1] These organogels, which are
dynamic and stimuli-responsive soft materials, have been used
in various fields including, sensing,[2] drug delivery,[3] tissue
engineering,[4] food,[5] cosmetics,[6a] and more.[6b-c] From the
mechanistic view, they represent a macroscopic expression of
the self-assembly of LMOGs via non-covalent interactions, into
one dimensional (1D) structures that eventually entangled into a
three dimensional (3D) network immobilizing the solvent. While
in most cases gels are obtained by a one-component LMOG,
that has to be dissolved in a hot solvent and later gelates under
cooling, in the case of a more intriguing gelation process two
components are mixed to form a gel at room temperature.[7,8]
Currently, two-component organogels are relatively rare, and
those displaying a unique combination of properties, such as
thixotropy, low minimal gelation concentration (MGC) and
thermal stability are even more scarce.[9]
Multivalency is an essential concept in Nature[10] that has been
adopted and used by supramolecular chemists to form complex
Figure 1. Rational design of pillararene-based nano-tubular supramolecular
polymers via multiple acid-base interactions.
[a]
Dr. Y. Zafrani*, D. Kaizerman, M. Hadar, N. Bigan, E. Granot. Prof.
Dr. F. Patolsky, Prof. Dr. Y. Cohen*
On the basis of the above hypothesis we discovered a new
family of two-component supramolecular organogels, formed at
low monomeric concentrations (<1% w/v), and displaying an
exceptional combination of physicochemical properties. We
also show that structural complementarity and multivalency are
important determinants in the gelation process of these
rationally designed two-component supramolecular, thixotropic,
tunable and thermally-stable organogels.
Pillararene derivatives used in the last decade for multiple
applications [14-16] were, very recently, also used to prepare few
organogels.[17-18] However, the two-component pillararene-
based organogels known, unlike those presented herein, were
formed by host-guest or metal-ligand interactions.
School of Chemistry, Sackler Faculty of Exact sciences
Tel Aviv University, Ramat Aviv 69978
Tel Aviv, Israel
E-mail:ycohen@post.tau.ac.il
Dr. Y. Zafrani,
Department of Organic Chemistry,
Israel Institute for Biological Research, Ness-Ziona 740000, Israel
E-mail: yossiz@iibr.gov.il
Dr. M. Gosh, Prof. Dr. L, Alder-Abramoivich
Department of Oral Biology, Goldschleger School of Dental
Medicine, Sackler Faculty of Medicine, Tel Aviv University,
Ramat Aviv 69978, Tel Aviv, Israel
[b]
[c]
Supporting information for this article is given via a link at the end of
the document
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The percarboxylato- (1) and peramino-pillar[n]arenes (2a-e,
3), used in this study were prepared by modifications of
previously reported procedures (see Schemes S1-S2 and
Figures S1-S17 in the Supporting Information Section (SI)).[16]
Because of solubility issues, we started examining the formation
of supramolecular gels by mixing solutions of 1 in DMSO and 2b
in CHCl3 in a 10:1 v/v. We found that at a concentration of 3.3
mM (1.0 % w/v), this mixture becomes a transparent gel that can
be further diluted to a minimum gelation concentration (MGC) of
1.7 mM (0.5 % w/v, Figure 2). Some assign LMOGs with such
low MGCs as supergelators.[19] Interestingly these stable soft
materials (months at room temperature) were found to be
with the bulkier amines (2e), mixing with 1 led to precipitation,
apparently due to steric effects weakening the interaction
between 1 and 2e. On the other hand, mixing 1 with the
homologues pillar[5]arenes 2c and 2d (having longer alkyl
chains) lead to the formation of organogels displaying different
properties. The 1:2b pair was found to be the best combination
for gelation in various organic solvents, leading to the formation
Table 1. MGC and Tgel values of organogels prepared from 1 and 2a-d.
[e]
run
solvent
gelator
MGC
Tgel
[% w/v][d]
thixotropic,
a
relatively rare feature in two-component
1
2
Various [a]
methanol
ethanol
1:2a
1:2b
P
VS
-
-
organogels with such low MGC (Figure 2).[9] Moreover and
interestingly, as also shown in Figure 2, these gels convert from
optically transparent to opaque upon heating, and collapse far
above the original boiling point of the immobilized chloroform
solvent (94oC at MGC). After vigorous shaking for 15 minutes,
followed by a resting period, the gels reform (Figure 2). A similar
behavior is also observed with the corresponding ethanolic gel
(Figure S18, SI). Pillar-[5]arenes 2b and 1 were dissolved in
CDCl3 and DMSO-d6, respectively, and their 1H-NMR spectra
are presented in Figure S19 (SI). Upon mixing equivalent
amounts of these solutions (0.6 % w/v in 10:1 CDCl3-DMSO-d6)
a transparent gel is observed, and the recorded 1H-NMR
spectrum exhibits no signals except some broad lines of the
residual solvents, suggesting a significant decrease in molecular
mobility (Figure S19C, SI).
3
G (0.4)
G (0.7)
G (0.4)
G (0.2)
P
115
79
101
62
-
4
2-propanol[b]
1-butanol[b]
1-octanol[b]
toluene
5
6
7
8
DMSO[c]
G (1.4)
G (1.1)
G (0.5)
P
69
86
94
-
9
DMF
10
11
12
13
14
15
16
17
18
Chloroform[b]
ethanol
1:2c
1-butanol[b]
DMF
G (0.5)
P
67
-
Chloroform[b]
ethanol
P
-
1:2d
1:2e
P
-
1-butanol[b]
Chloroform[b]
Various [a]
G (0.8)
S
83
-
P
-
[a] Ethanol, chloroform, 1-butanol, DMF, 1-octanol. [b] With DMSO as co-
solvent (5-10% v/v).[c] With chloroform as co-solvent (10 % v/v). [d]
Abbreviations used: G = gel; P = precipitate; VS = viscous solution; S =
solution. [e] Here the Tgel values refers to the collapse temperature (in DMF
the process is irreversible).
Figure 2. Photographs of the two-component chloroform-DMSO (10:1) gel
formed between 1 and 2b, and its stimuli responsiveness to shaking and heat.
1
In addition, even for H-NMR spectra taken immediately after a
1
vigorous shaking converting the gel to a clear solution, no H-
of organogels with superior physical properties. The results
presented in Table 1 reveal that it is possible to tune the
properties of the obtained organogels by tailoring the lipophilicity
(or size) of the amine group on the pillararene skeleton. To
further explore the effect of the amine group we examined the
interaction between 1 and 2b-d in CDCl3-DMSO-d6 (10:1 v/v)
solutions. Interestingly, while the 1:2b pair forms an organogel in
these deuterated solvents, the 1:2c pair precipitates and their
more lipophilic counterpart 1:2d pair forms a clear solution.
Inspection of the 1H NMR spectra of these three phases, i.e. the
transparent gel, the suspension and the clear solution revealed
that in all cases most signals of both molecular components
were too broad to be observed (Figures S19-S21, SI). These
NMR signals of 1 or 2b could be observed, indicating that not
only the 3D-structure, but also the lower hierarchical self-
assembled 1D structures, have limited mobility. Table 1 presents
the MGC values and the gel-to-solution (suspension) transition
temperatures (Tgel) of the different organogels formed between 1
and 2a-e in various organic solvents. This Table shows that
different organic solvents allow the formation of gels between 1
and 2b, with a higher tendency to gelate in chloroform and
alcohols. Table 1 also shows that both, the gelation readiness
and gel properties are strongly dependent on the alkyl
substituents on the amine groups. With primary amines (2a), no
gelation occurs in any of the tested organic solvents. Similarly,
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results suggest that in the hierarchical assembly of the pillar-
shaped components 1 and 2b-d, not only the 3D-networks but
also the 1D-structures are too immobile to be observed in the 1H
NMR spectra.
thixotropic nature of the organogels could be demonstrated by
measuring the recovery of their mechanical strength after a large
amplitude oscillatory breakdown. For the ethanolic gel, the initial
storage modulus (G’) value was about 327 Pa; dropping to 19
Pa under a large amplitude oscillatory force of 100% strain and
1.0 Hz frequency, indicating the transformation to a sol-state.
The gel regains its gelation property as the oscillation amplitude
decreases to 0.1% at the same frequency of 1.0 Hz, and G’
recovers to about 426 Pa, representing the recovery of a gel
state (Figure 3c). Similarly, for the octanolic gel, the initial value
of G’ is about 1484 Pa, displaying a larger rigidity than its
ethanolic counterpart. Under 100% oscillatory force strain
amplitude and 1.0 Hz frequency, G' reaches a value of 8 Pa, and
recovers again to 2040 Pa indicating the thixotropic property of
the gel (Figure 3d). Furthermore, this thixotropic process could
be repeated multiple times (see also Figures S26 and S27, SI),
with an increase in G’ values observed during the first cycles
until a steady state is achieved.
We next examined the optimal 2b:1 ratio for gelation and
found, not surprisingly, using Tgel determination, that the 1:1 ratio
is the optimal stoichiometry for gelation (see Figure S22 in SI).
1H NMR analysis of these samples shows no signals for both
components when the 2b:1 ratio was 1:2, 2:3 and 1:1. When 2b
was in excess it was observed in the 1H NMR spectra and when
its concentration was twice that of 1 the measured Tgel was
significantly lower, implying that this excess, in fact, disturbs the
gelation process (Figures S22-S23, SI). Interestingly, during the
thermo-stability measurements we found that all these
organogels have the same characteristics and in all these cases,
except for the DMF-based gels, after the heating-cooling cycles,
the gel state could be recovered from the turbid solutions by
vigorous shaking before the resting period. It appears that upon
heating, the 3D-networks reorganize into more organized
structures. Note that we found only few cases in which
organogels become more rigid, and/or more opaque, under
heating.20 These thermal behavior is reminiscent of the so-called
thermogels (or injectable hydrogels).21 Contrary to thermogels,
our organogels did not liquidify under cooling. In addition, Tgel
was measured using the test tube inversion method at different
concentrations of organogels made between 1 and 2b in ethanol,
butanol, octanol and DMF (Figure S24). In all four cases the Tgel
values increase with the increase in the LMOG concentrations.
Note that at all concentrations, the translucent gel becomes
opaque and finally collapses alongside precipitation upon
heating. Interestingly, when the resulting turbid solution is
vigorously shaken by vortex, this process was found to be
reversible in all the protic solvents tested but not in DMF. For
1
DMF, this process was also followed by H NMR (Figure S25).
All these findings are probably the manifestation of the
continued organization of the 3D-network upon temperature
increase. Regarding the alcoholic solvents, one may conclude
that the 3D-network growth is controlled by the lipophilicity of the
alcohol. These results suggest that the organogels can be easily
tuned by the solvent nature.
Another interesting feature of the above-mentioned
organogels is their thixotropy, even at their MGC, in many cases
being lower than 1 % w/v of the gelator. The shaking-resting
cycle could be repeated countless times, and the sol-gel
recovery time can be easily tuned from seconds to several hours
as a function of the concentration and solvent type. The
responsiveness to mechanical stimuli in the ethanolic and
octanolic organogels, based on the 1:2b pair, was investigated
by rheological means. First, dynamic frequency sweep (at 0.1%
strain) and strain sweep (at 1 Hz) oscillatory measurements
were performed to optimize the appropriate measurement
Figure 3. Rheological analysis of 5mM (~1.6% wtv) ethanolic and
octanolic organogels of 1:2b at 25 oC: (a) G’ and G” values as a function of
frequency sweep, (b) G’ and G” values as a function of strain sweep, and as a
function of continuous step strain for (c) ethanol and (d) octanol.
Next, we studied the importance of multivalency and
structure complementarity in the formation of these
supramolecular organogels both, macroscopically by following
1
gel formation, and molecularly by following their H NMR spectra.
We assumed that the pre-organized multivalent sites of
pillararenes 1 and 2b have a pivotal role in the hierarchical self-
assembly process and the eventual gel formation in these
systems. To explore these important issues, we monitored the
gel formation process of the 1:2b pair and the interaction
between the two acyclic monomers, 1,4-bis-diethylamino-
ethoxybenzene (4) and 1,4-bis-carboxylato-methoxybenzene (5)
in CDCl3-DMSO-d6 solutions (10:1 v/v). The 1H NMR spectra
presented in Figure S28, showing significant changes in
chemical shift upon mixing of the two monomeric materials,
conditions. The frequency sweep experiments, using
a
frequency range of 0.1-100 Hz, showed wide linear
a
viscoelastic range (LVR) in both ethanolic and octanolic gels
(Figure 3a). Furthermore, to analyse the effect of oscillatory
strain, the organogels were subjected to 0.01-100% strain
sweep which showed a LVR of up to 10% strain (Figure 3b). The
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clearly demonstrate the existence of strong acid-base and π-π-
interactions between 4 and 5 in this solution. However, when 1
was mixed with five equivalents of the monomeric diamine 4 a
spherical assemblies, was previously reported in the literature.[23]
Interestingly, after heating this gel to its Tgel value (96oC),
followed by vigorous shaking of the turbid solution and resting,
led to a change in morphology of the resulting xerogel from
microspheres to microcubes (Figure 5b).
1
precipitate was formed (Figure 4). This is corroborated by the H
NMR spectra presented in Figure S29. These results suggest
that both, the rigid decaamine and deca-carboxylic pillararenes
are required for the organogels formation. To obtain further
insights regarding the structural complementarity needed for gel
formation in these systems, we added the dodeca-diethylamino
pillar[6]arene 3 to the solution of the pentameric pillararene 1.
Interestingly, no gel formation was observed. This mixture led to
the formation of a precipitate, probably due to non-specific
random interactions between 1 and 3 (Figure 4 and Figure S30).
Next, we proceeded to investigate the process of gel formation
between 1 and 2b in the presence of 3 or 4. We found that these
three-component systems afford organogels in the CDCl3-
Figure 5. SEM images from chloroform-DMSO (10:1) gel. (a) Xerogel
obtained from the 2 mM 1:2b gel before heating to Tgel; b) Xerogel of the same
preparation after heating to Tgel, shaking and resting.
1
DMSO-d6 solution (10:1 v/v), as shown in Figure 4. H NMR
analysis of these gels clearly shows that in both cases the
signals of 1 and 2b are significantly broadened, while those of
the third component, 3 or 4, remain much sharper as shown in
Figures S31-S32. Moreover, diffusion NMR experiments[22] of
the later three-component organogels revealed that the diffusion
coefficients of the third components, 3 and 4, remain similar to
those measured for the isolated compounds in the above
solvents (Figure S33 and Table S1, SI). In addition, the Tgel
value is less affected when the third component is the monomer
4, compared to the situation when the third component is the
hexameric macrocycle 3 (Figure 4). All these results are a
manifestation of the pivotal role played by multivalency and
structural complementarity during the formation of the two-
component pillararene-based organogels.
These results suggest that the resulting 3D networks
significantly change upon gel heating, as also visually observed
when the transparent gel becomes a turbid solution at the Tgel
.
Both DMF and i-PrOH-based gels exhibit similar coralloid
morphology, contrary to the ethanolic gel, that displays a smooth
surface with sporadic strands (Figure S34). Remarkably, the
homologous pairs 1:2c (precipitation) and 1:2d (clear solution)
exhibit a rough surface and intertwined fibrils, respectively
(Figure S36, SI), suggesting that with these two candidates,
which eventually failed to produce a gel, the initial self-assembly
do occur, as also observed by 1H NMR spectra presented in
Figures S20B and S21B. In a control SEM imaging experiment,
a solution of the decacarboxylato-pilar[5]arene 1 showed micron
sized rod-like structures (5 µm, Figure S36, SI). Remarkably, the
gel formed by mixing 1 and 2b in the presence of 4 exhibited a
homogeneous dispersion of microspheres (ca 3 µm) wrapped by
thick fibers (ca 0.2 µm) as shown in Figure S37 (SI). The gel
formed by 1 and 2b in the presence of 3 displayed sub-micron
size spheres (Figure S37, SI). Based on the above results a
plausible mechanism for the formation of the pillararene-based
organogels is presented in Figure 6.
Figure 4. Photographs of the different phases obtained in CDCl3-
DMSOd6 (10:1) by mixing 1 with 2b or 3 or 4, and for the 1:2b pairs in the
presence of 3 and 4.
Finally, the morphology of selected xerogels and some of
the related non-gel systems were studied by scanning electron
microscopy (SEM). The images of a representative xerogel
prepared by a 2mM solution of 1:2b, in chloroform-DMSO (10:1
v/v), reveal nano- to micro-sized spheres (0.2-1.3 µm) on and
around coralloid structures (Figure 5a). Such interesting
morphology, reflecting evolution of nano- to micron-sized
Figure 6. A plausible mechanism for the formation of the two components
pillararene-based supramolecular organogels.
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[6]
(a) S. Uzan, D. Baris, M. Colak, H. Aydin, H. Hosgoren, Tetrahedron,
2016, 72, 7517-7525. (b) B. O. Okesola, V. M. P. Vieira, D. J. Cornwell,
N. K. Whitelaw, D. K. Smith, Soft Matter 2015, 11, 4768-4787. (c) T
Cardolaccia, Y. Li, K. S. Schanze, J. Am. Chem. Soc. 2008, 130, 2535-
2545.
In light of the facts that; a) the optimal ratio for gelation was
found to be 1:1, i.e. excess of 2b was observed by 1H NMR and
excess of 1 simply precipitated; b) the organogels are formed via
shape-based complementarity, i. e. only when pentagonal are
facing pentagonal structures; c) the 1:2b pair effectively forms
organogels in the presence of 4, 5 and even 3, it is plausible to
assume that the self-assembly between 1 and 2 occurs via
alternate organization of these two components as described in
Figure 6. Note that the formation of 1D nanotubes of
[7]
[8]
A. R. Hirst, D. K. Smith, Chem. Eur. J. 2005, 11, 5496-5508.
Selected examples: (a) W. Miao, L. Qin, D. Yang, X. Jin, M. Liu, Chem.
Eur. J. 2015, 21, 1064-1072. (b) Y. He, M. Xu, R. Gao, X. Li, F. Li, X.
Wu, D. Xu, H. Zeng, L. Yuan, Angew. Chem. Int, Ed. 2014, 53, 11834-
11839. (c) W. Edwards, D. K. Smith, J. Am. Chem. Soc. 2013, 135,
5911-5920. (d) Y. Zhou, M. Xu, T. Yi, S. Xiao, Z. Zhou, F. Li, C. Huang,
Langmuir 2007, 23, 202-208. (e) S. Yagai, M. Higashi, T. Karatsu, A.
Kitamura, Chem. Mater. 2004, 16, 3582-3585. (f) A. R. Hirst, D. K.
Smith, M. C. Feiters, H. P. M. Geurst, A. C. Wright, J. Am. Chem. Soc.
2003, 125, 9010-9011.
pillar[5]arenes was recently suggested.[24]
Based on the
significant difference in the pKa values of 1 and 2, one can
assume, that their assembly to supramolecular nanotubes
occurs via multiple charge-assisted hydrogen bonds,[25] which
overcome the competition of the surrounding polar protic/aprotic
solvent molecules. Note that addition of solid NaOH disrupts to
formed supramolecular gels. The formed 1D structure may, then,
aggregate to fibers via both charge-assisted hydrogen bonds
and - interactions that eventually lead to the entangled
structures.
In conclusion, we found, by rational planning, a new family
of two-component, supramolecular organogels based on
structurally complementary pillararenes. These supramolecular
organogels, presumably consisting of hollow nano-tubular
structures, obtained by simple mixing (no heating required), in
different organic solvents, were found to be thixotropic and are
characterized by high stability, low MGC and high Tgel values,
which in some cases exceed the boiling point of the embedded
solvent. Importantly, we demonstrated that the different
characteristics of these organogels are tunable. By performing
competition experiments, and following them macroscopically
and by 1H NMR, we could demonstrate the importance of
multivalency and structural complementarity in the formation of
such organogels. A plausible mechanism for the formation of
these supramolecular organogels is also suggested.
[9]
P. Mukhopadhyay, N. Fujita, A. Takada, T. Kishida, M. Shirakawa, S.
Shinkai, Angew. Chem. Int. Ed. 2010, 49, 6338-6342.
[10] (a) S. Bhatia, L. C. Camacho, R. Haag, J. Am. Chem. Soc. 2016, 138,
8654-8566. (b) A. Barnard, D. K. Smith, Angew. Chem. In. Ed. 2012, 51,
6572-6581.
[11] (a) D. T. Bong, T. D. Clark, J. R. Granja, M. R. Ghadiri, Angew. Chem.
Int. Ed. 2001, 40, 988-1011. (b) L. S. Shimizu, S. R. Salpage, A. A.
Korous, Acc. Chem. Res. 2014, 47, 2116-2127. (c) A. Nitti, A. Pacini, D.
Pasini, Nanomaterials 2017, 7, 167.
[12] (a) L. R. MacGillivray, J. L. Atwood, Nature 1997, 389, 469-472. (b) L.
Avram, Y. Cohen, J. Am. Chem. Soc.2002, 124, 15148-15149. (c) L.
Avram, Y. Cohen, J. Rebek, Chem. Commun. 2011, 47, 5368-5375. (d)
J. Rebek, "hydrogen-bonded capsules: molecular behavior in small
spaces" World Scientific Publishing, Singapore, 2015.
[13] (a) E. Krieg, M. M. C. Bastings, P. Besenius, B. Rybtchinski, Chem.
Rev. 2016, 116, 2014-2477. (b) S. Dong, B. Zheng, F. Wang, F. Huang,
Acc. Chem. Res. 2014, 47, 1982-1994.
[14] (a) T. Ogoshi, S. Kanai, S. Fujinami, T.-A. Yamagishi, Y. Nakamoto, J.
Am. Chem. Soc. 2008, 130, 5022-5023. For a few recent reviews on
pillararenes see: (b) T. Kalkuta, T.-A. Yamagishi, T. Ogoshi, Chem.
Comm. 2017, 53, 5250-5266. (c) C. W. Sathiyajith, R. R. Shaikh, Q.
Han, Y. Zhang, K. Meguellati, Y.-W. Yang, Chem. Comm. 2017, 53,
677-696. (d) T. Ogoshi, Yamagishi, T. -A. Y. Nakamoto, Chem. Rev.
2016, 116, 7937-8002. (e) C. Li, Chem. Commun. 2014, 50, 12420-
12433. (f) N. l. Strutt, H. Zhang, S. T. Schneebeli, J. F. Stoddart, Acc.
Chem. Res. 2014, 47, 2631-2642.(g) T. Ogoshi, T. -A. Yamagishi,
Chem. Commun. 2014, 50, 4776-4787. (h) J.-F. Chen, Q. Lin, Y.-M.
Zhang, H. Yao, T.-B. Wei, Chem. Comm. 2017, 53, 13296-13311. (i) K.
Yang, Y. Pei, J. Wen, Z. Pei, Chem. Commun. 2016, 52, 9316-9326.
[15] (a) G.C. Yu, J. Zhou, J. Shen, G. Tang, F. Huang, Chem. Sci. 2016, 7,
4073-4078. (b) K. C. Jie, M. Liu, Y.J. Zhou, M. A. Little, S. Bonakala, S.
Y. Chong, A. Stephenson, L. Chen, F. Huang, A. I. Cooper, J. Am.
Chem. Soc. 2017, 139, 2908–2911. (c) T. Ogoshi, R. Sueto, K.
Yoshikoshi, K. Yasuhara, T.-A. Yamagishi, J. Am. Chem. Soc. 2016,
138, 8064-8067. (d) T. Ogoshi, H. Kayama, D. Yamafuji, T. Aoki, T.-A.
Yamagishi, Chem. Sci. 2012, 3, 3221--3226.
Keywords: organogels • pillararenes • self-assembly •
thixotropy• multivalency
[1]
Selected recent reviews: (a) S. Cherumukkil, B. Vedhanarayanan, G.
Das, V. K. Praveen, A. Ajayaghosh, Bull. Chem. Soc. Jpn. 2018, 91,
100-120. (b) E. R. Draper, D. J. Adams, Chem. 2017, 3, 390-410. (c) N.
Singh, M. Kumar, J. F. Miravet, R. V. Ulijn, B. Escuder, Chem. Eur. J.
2017, 23, 981-993. (d) S. Manchineella, T. Govindaraju,
ChemPlusChem 2017, 82, 88-106. (e) K. Hanabusa, M. Suzuki, Bull.
Chem. Soc. Jpn. 2016, 89, 174-182. (f) J. Raeburn, D. J. Adams, Chem.
Commun. 2015, 51, 5170-5180. (g) R. G. Weiss, J. Am. Chem. Soc.
2014, 136, 7519-7530. (h) L. E. Buerklea, S. J. Rowan, Chem. Soc.
Rev. 2012, 41, 6089-6102. (i) J. W. Steed, Chem. Commun. 2011, 47,
1379-1383 (j) P. Dastidar, Chem. Soc. Rev. 2008, 37, 2699-2715. (k) N.
M. Sangeetha, U. Maitra, Chem. Soc. Rev. 2005, 34, 821-836.
(a) K. K. Kartha, S. S. Babu, S. Srinivasan, A. Ajayaghosh, J. Am.
Chem. Soc. 2012, 134, 4834-4841, (b) A. Kishimura, T. Yamashita, T.
Aida, J. Am. Chem. Soc. 2005, 127, 179-183.
[16] (a) R. Joseph, A. Naugolny, M. Feldman, I. M. Herzog, M. Fridman, Y.
Cohen, J. Am. Chem. Soc. 2016, 138, 754–757. (b) R. Joseph, D.
Kaizerman, I. M. Herzog, M. Hadar, M. Feldman, M. Fridman, Y. Cohen,
Chem. Commun. 2016, 52, 10656-10659. (c) T. Adiri, D. Marciano, Y.
Cohen, Chem. Commun. 2013, 49, 7082-7084.
[2]
[3]
[17] (a) M. Ni, N. Zhang, W. Xia, X. Wu. C. Yao, X. Liu, X.-Y. Hu, C. Lin, L.
Wang, J. Am. Chem. Soc. 2016, 138, 6643-6649. (b) L. Gao, B. Zheng,
Y. Yao, F. Huang, Soft Matter 2013, 9, 7314-7319. (c) Y. Yao, Y. Sun,
H. Yu, W. Chen, H. Dai, Y. Shi, Dalton. Trans. 2017, 46, 16802-16806.
(d) W. Xia, M. Ni, C. Yao, X. Wang, D. Chen, C. Lin, X.-Y. Hu, L. Wang,
Macromolecules, 2015, 48, 4403-4409. (e) Q. Lin, P.-P. Mao, Y.-Q. Fan,
L. Liu, J. Liu, Y.-M. Zhang, , H. Yao, T.-B. Wei, Soft Matter 2017, 13,
7085-7089.
(a) A. Vintiloiu, J.-C. Leroux, J. Control. Relaese 2008, 125, 179-192.
(b) S. S. Sagiri, B. Behera, R. R. Rafanan, C. Bhattacharya, K. Pal, I
Banerjee, D. S. Rousseau, Soft Matter. 2014, 12, 47-72.
[4]
[5]
K. J. Skilling, F. Citossi, T. D. Bradshaw, M. Ashford, B. Kellam, M.
Marlow, Soft Matter. 2014, 12, 237-256.
H. Yu, K. Shi, D. Liu, Q. Huang, Food Chemistry 2012, 131, 48-54.
[18] (a) Z.-Y. Li, Y. Zhang, C.-W. Zhang, L.-J. Chen, C. Wang, H. Tan. Y. Yu,
X. Li, H.-B. Yang, J. Am. Chem. Soc. 2014, 136, 8577-8589. (b) X.
This article is protected by copyright. All rights reserved.

10.1002/chem.201801418
Chemistry - A European Journal
COMMUNICATION
Zhang, J. Xu, C. Lang, S. Qiao, G. An, X. Fan, L. Zhao, C. Hou, J. Liu,
Biomacromolecules, 2017, 18, 1885-1892. (c) J. Chang, Q. Zhao, L.
Kang, H. Li, M. Xie, X. Liao, Macromolecules, 2016, 49, 2814-2820. (d)
Y. Liu, L. Shangguan, H. Wang, D. Xia, B. Shi, Polym. Chem. 2017, 8,
3783-3787. (e) V. Kardelis, K. Li, I. Nierengarten, M. Holler, J.-F.
Nierengarten, A. Adronov, Macromolecules 2017, 50, 9144-9150.
[19] R. G. Weiss, P. Terech, Molecular Gels Materials with Self-Assembled
Fibrillar Networks, Springer, Dordrecht, 2006. (b) D. K. Smith, in
Organic Nanostructures, ed. J. L. Atwood and J. W. Steed, WILEY-
VCH, Weinheim, 2008, pp. 111–148.
[21] L. Yu, J. Ding, Chem. Soc. Rev. 2008, 37, 1473-1481.
[22] Y. Cohen, L. Avram, L. Frish, Angew. Chem. Int, Ed. 2005, 44, 520-554.
(b) L. Avram, Y. Cohen, Chem. Soc. Rev. 2015, 44, 586-602.
[23] (a) A. Ajayaghosh, R. Varghese, V. K. Praveen, S. Mahesh, Angew.
Chem. Int. Ed. 2006, 45, 3261-3264. (b) C.-C. Tsai, K.-C. Chang, I-T.
Ho, J.-H. Chu, Y.-T. Cheng, L.-C. Shen, W.-S. Chung, Chem. Commun.
2013, 49, 3037-3039.
[24] T. Ogoshi, S. Takashima, T.-A. Yamagishi, J. Am. Chem. Soc. 2018,
140, 1544-1548.
[25] (a) P. Gilli, L. Pretto, V. Bertolasi, G. Gilli, Acc. Chem. Res. 2009, 42,
33-44. (b) M. Thomas, T. A. Lagones, M. Judd, M. Morshedi, M. L.
OMara, N. G, White, Chem. Asian. J. 2017, 12, 1587-1597.
[20] (a) S. Ghosh, R. D. Mahapatra, J. Dey, Langmuir 2014, 30, 1677-1685.
(b) Y- S. Kim, Y-G. Cho, D. Odkhuu, N. Park, H-K. Song, Sci. Rep.
2013, 3, 1917.
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A rational design of a new family
of supramolecular organogels
based on percarboxylato- and
Yossi Zafrani*, Dana Kaizerman,
Maya Hadar, Nitzan Bigan, Eran
Granot, Moumita Gosh, Lihi
Alder-Abramovich, Fernando
Patolsky, Yoram Cohen*
perdialkylamino-pillararenes
is
presented. These low MGC
organogels obtained with no
heating are thixotropic and
thermally stable with Tgel in cases
exceeding the boiling point of the
solvent. Structural complemen-
tarity and multivalency are shown
to be important determinants of
their gelation process.
Page No. – Page No.
Pillararene-based Two
Components Thixotropic
Supramolecular Organogels:
Complementarity and
Multivalency as Prominent
Motifs
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Author(s), Corresponding Author(s)*
((Insert TOC Graphic here))
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Title
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