Pillar[5]arene-Based [2]Rotaxane: Synthesis, Characterization, and Application in a Coupling Reaction

Article abstract of DOI:10.1021/acs.inorgchem.0c01752

Mechanically interlocked molecules are a class of smart supramolecular species because of their interesting topological structure and application in various areas, such as biology and nanoscience. In this work, we used "multicomponent reaction"to fabricate a new [2]rotaxane based on pillar[5]arene from different small-sized molecules. The molecular structure of the obtained [2]rotaxane R was confirmed by 1H and 13C NMR, high-resolution electrospray ionization mass spectrometry, two-dimensional nuclear Overhauser effect spectroscopy, and density functional theory studies. Interestingly, the [2]rotaxane-based organometallic cross-linked catalyst (Pd?R) was easily constructed via the coordination between triazole groups and Pd(NO3)2. Pd?R proved to be a good catalyst for the Suzuki-Miyaura coupling reaction with excellent stability and repeatability.

Full text of DOI:10.1021/acs.inorgchem.0c01752

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Pillar[5]arene-Based [2]Rotaxane: Synthesis, Characterization, and
Application in a Coupling Reaction
Hao Guo, Junmei Ye, Zhecheng Zhang, Yang Wang, Xiaolei Yuan, Changjin Ou, Yue Ding,
Chaoguo Yan,* Jin Wang, and Yong Yao*
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ABSTRACT: Mechanically interlocked molecules are a class of smart supramolecular species because of their interesting
topological structure and application in various areas, such as biology and nanoscience. In this work, we used “multicomponent
reaction” to fabricate a new [2]rotaxane based on pillar[5]arene from different small-sized molecules. The molecular structure of the
1
13
obtained [2]rotaxane R was confirmed by H and C NMR, high-resolution electrospray ionization mass spectrometry, two-
dimensional nuclear Overhauser effect spectroscopy, and density functional theory studies. Interestingly, the [2]rotaxane-based
organometallic cross-linked catalyst (Pd@R) was easily constructed via the coordination between triazole groups and Pd(NO ) .
3
2
Pd@R proved to be a good catalyst for the Suzuki−Miyaura coupling reaction with excellent stability and repeatability.
echanically interlocked molecules (MIMs) are a type of
smart supramolecular species because of their interest-
Scheme 1. Classical Large Size Stoppers in Construction
Pillar[5]arene-Based [2]Rotaxanes
M
ing topological structure and wide application in biology and
1
nanoscience areas. [2]Rotaxane, which contains a dumbbell-
like architecture with a macrocycle sliding along a linear axle, is
a popular MIM and can be treated as an ideal candidate for
molecular machines and devices. Currently, on the one hand,
many well-know macrocycle compounds, such as crown ethers,
cyclodextrins, calixar[n]arenes, and cucurbiturils, have been
pillar[5]arene-based [2]rotaxane from different small-sized
molecules (Scheme 2a). Interestingly, [2]rotaxane-based
organometallic cross-linked catalyst (Pd@R) was easily
constructed via the coordination between triazole groups and
Pd(NO ) . Pd@R proved to be a good catalyst for the
Suzuki−Miyaura coupling reaction with excellent stability and
repeatability (Scheme 2b).
The synthetic process of pillar[5]arene-based [2]rotaxane R
was shown in Scheme 2. At first, the aliphatic chain axle G was
successfully prepared in two steps. The substitution reaction of
dibromohexane and sodium azide was dispersed in dimethyl-
formamide (DMF) with tetra-n-butylammonium bromide
2
applied as wheel components to fabricate [2]rotaxanes. On
the other hand, various molecular recognition motifs, such as
crown ethers/ammonium salts, have been utilized to
3
investigate the [2]rotaxane-based molecular motions.
3
2
Pillar[5]arenes, a new class of “popular” macrocyclic hosts,
were designed and prepared by Ogoshi and co-workers in
2
008. During the past decade, the synthetic methods, host−
guest properties, and applications of pillar[5]arenes have been
developed rapidly. On the one hand, pillar[n]arenes possess a
4
more rigid structure than crown ethers and calixar[n]arenes,
which made a large number of guests suitable for pillar[n]-
arenes. On the other hand, it is easier to prepare and
functionalize pillar[n]arenes than cyclodextrins and cucurbi-
turils. Stoddart and co-workers designed and developed the
first pillar[5]arene-based [2]rotaxane in 2011 with pillar[5]-
arene as the wheel, 1,8-diaminooctane as the axle, and 3,5-di-
(
TBAB) as a phase-transfer catalyst to give the desired
diazoalkanes, which in turn reacted with 4-(prop-2-yn-1-
yloxy)benzaldehyde according to the copper-catalyzed azide-
alkyne cycloaddition (CuAAC) reaction to give the desired
axle G. As we know, G and perethylpillar[5]arene can form a
5
tert-butylbenzaldehyde as the stopper.
10
stable complex in a solvent (Figure S13). Then, for the
After this pioneer, various types of pillar[5]arene-based
2]rotaxanes have been fabricated by other research groups.
construction of pillar[5]arene-based [2]rotaxane, the tradi-
tional threading-stopper method was employed. The mixture
6
[
However, when constructing pillar[5]arene-based [2]-
rotaxanes, most of the previous methods used a large-sized
stopper that reacted with the linear axle (Scheme 1); this
significantly restrained the diversity of [2]rotaxanes. Therefore,
it is quite necessary to develop a new strategy to fabricate
pillar[5]arene-based [2]rotaxanes. Furthermore, the investiga-
Received: June 14, 2020
7
tion of rotaxane’s application has rarely been reported. In this
article, we used a “multicomponent reaction” to fabricate a new
©
XXXX American Chemical Society
https://dx.doi.org/10.1021/acs.inorgchem.0c01752
A
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a
Scheme 2
Then the three-component reaction, in refluxing ethanol, of
dimedone, malononitrile, and benzaldehyde catalyzed by
piperidine was applied as the stopper formation reaction.
The expected [2]rotaxane R was successfully prepared in a
moderate yield. The molecular structure of the obtained
1
13
[2]rotaxane R was thoroughly investigated by H NMR,
C
NMR, two-dimensional (2D) nuclear Overhauser effect
spectroscopy (NOESY), high-resolution electrospray ioniza-
tion mass spectrometry (HR-ESI-MS), and density functional
theory (DFT) studies.
1
From the H NMR spectra we found that Hb, Hc, Hd, and
He in the linear axle of R showed obvious upfield shifts (−Δδ
=
0.52−3.03 ppm) compared with those of compound 1
(
Figure 1a,b). On the one hand, this phenomenon can be
explained by the encapsulation-induced shielding effects. On
the other hand, the Hi of wheel pillar[5]arene showed
downfield shifts compared with free pillar[5]arene because of
the deshielding effects. What’s more, Hd and He also located
below 0 ppm after being heated in the highly polar solvent
deuterated dimethyl sulfoxide (DMSO-d ) at 75 °C overnight
6
(
Figure S2), indicating that the stopper constructed by
multicomponent reaction is bulky enough. 2D NOESY NMR
spectroscopy also gives credible evidence for the formation of
[2]rotaxane. As shown in Figure 2, the 2D NOESY NMR
spectroscopy of R in DMSO-d6 showed strong nuclear
Overhauser effect (NOE) correlation signals between the
pillar[5]arene wheel (Hh, Hi, Hg, and Hf) and the compound
1 axle (Hb, Hc, Hd, and He), indicating that the alkyl chain on
the axle penetrated into the perethylpillar[5]aren cavity to
form a host−guest complex. Furthermore, the exact mass of
the obtained [2]rotaxane was given by HR-ESI-MS (Figure
a
(
a) The synthetic route to [2]rotaxane based on pillar[5]arene (R)
and the chemical structure of compound 1. (b) Cartoon
representation of the formation of Pd@R and its application in the
coupling reaction.
S6). A relative peak was found at 1756.9103, which
+
of G and perethylpillar[5]arene was stirred in CHCl and
corresponded to C103H123N O ([M + H] ) for R.
3
10 16
CH CH OH at room temperature for 12 h, which enabled the
axle to be threaded into the cavity of perethylpillar[5]arene.
To better understand the topological structures of the
[2]rotaxane, a theoretical calculation using the density
3
2
1
Figure 1. H NMR spectra (rt, 400 MHz, DMSO-d ) of (a) compound 1, (b) [2]rotaxane R, and (c) perethylpillar[5]arene.
6
B
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Figure 2. NOESY spectrum of [2]rotaxane R (rt, 400 MHz, DMSO-d6).
functional theory for R was also performed. As shown in Figure
3
, the calculated results gave direct evidence that the aliphatic
Figure 4. (a) TEM image of Pd@R. (b) The corresponding EDX
spectrum of Pd@R.
Figure 3. (a) Side view, (b) top view, and (c) space-filling view of the
calculated structure of R3 at the B3LYP/6-31G(D) level using the
polarizable continuum model in DMSO, where only the hydrogens in
question are given for clarity. The gray dashed lines indicate C−H···π
interactions and H bonds.
(
EDX), powder X-ray diffraction (XRD) analysis, and scanning
electron microscopy (SEM) mapping provided direct evidence
for the incorporation of Pd in the polymeric materials (Figures
4
8
b, S11, and S12).
With Pd@R in hand, the Suzuki coupling reaction was
9
selected to investigate its catalytic capability. As shown in
Table 1, the catalytic activity of Pd@R is ∼95% overnight.
What’s more, the Pd@R catalyst can be reused for several
chain on 1 was located in the perethylpillar[5]arene cavity to
form stable [2]rotaxane. The distances of the C−H···π and H
bonds are from 2.3 to 2.9 Å, which is shorter than 3.05 Å.
What’s more, the angles of C−H···π were larger than 90°,
indicating the formation of multiple C−H···π interactions. All
a
Table 1. Suzuki-Miyaura Coupling Reaction Catalyzed by
Pd Catalysts
1
the H NMR, 2D NOESY, HR-ESI-MS, and DFT results
confirmed the construction of pillar[5]arene-based [2]-
rotaxane.
From the structural features of our [2]rotaxane, we can see
that there are two triazole units on the axle; the triazole units
can act as anchoring sites for metal-based catalysts. Taking R as
an example, Pd(NO ) was conveniently introduced to form
yields of conversion (%)
catalyst
cycle 1
cycle 2
93
cycle 3
95
3
2
Pd@R
Pd(NO3)2
Pd@1
95
30
66
2
+
Pd -loaded supramolecular polymeric materials through the
coordination interaction between the triazole groups and the
Pd ions. After the addition of Pd(NO ) into the solution of R,
65
66
3
2
polymeric materials (Pd@R) were created immediately. A
transmission electron microscopy (TEM) image showed that it
was formed by hinges of small particles with a diameter of 50
nm (Figure 4a). Further, energy-dispersive X-ray spectroscopy
a
Reaction conditions: Phenyl-OTf (1.00 mmol), 4-boronic acid
pyridine (1.50 mmol), K CO (2.00 mmol), catalyst (0.50 mol % Pd),
DMF (5 mL), 100 °C. Yields were determined by gas chromatog-
raphy/mass spectrometry (Agilent 1260).
2
3
C
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cycles without any loss of conversion ratio. From the X-ray
photoelectron spectroscopy (XPS) analysis, we found that,
after the coupling reaction, Pd(II) in the catalyst transformed
into Pd(0); however, the Pd(0) particles were still
incorporated in the polymeric materials, so after the catalyst
was cycled three times, the XPS spectra did not show any
changes compared with the catalyst used after the first time
Authors
Hao Guo − School of Chemistry and Chemical Engineering,
Yangzhou University, Yangzhou, Jiangsu 225000, P. R. China;
School of Chemistry and Chemical Engineering, Nantong
University, Nantong, Jiangsu 226019, P. R. China
Junmei Ye − School of Chemistry and Chemical Engineering,
Yangzhou University, Yangzhou, Jiangsu 225000, P. R. China
Zhecheng Zhang − School of Chemistry and Chemical
Engineering, Nantong University, Nantong, Jiangsu 226019, P.
R. China
Yang Wang − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China;
orcid.org/0000-0003-2500-5708
Xiaolei Yuan − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China;
orcid.org/0000-0002-8660-7246
Changjin Ou − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China
Yue Ding − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China
Jin Wang − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China
(Figure S16). A TEM image also confirmed that Pd(0)
particles were incorporated in the polymeric catalyst after three
times cycling and that the polymeric catalyst maintained its
spherical morphology (Figure S17). Furthermore, different
substrates were investigated in the coupling reaction, all giving
good yields (Table S2). For comparison, Pd(NO ) and the
3
2
Pd/compound 1 complex (Pd@1) were also used to catalyze
the coupling reaction under the same conditions. On the one
hand, it was found that the use of Pd(NO ) instead of Pd@R
3
2
caused the conversion of the coupling reaction to decrease to
0%. Moreover, it is difficult to recover and reuse Pd(NO ) .
3
3
2
On the other hand, the conversion of Pd@1 as catalyst was
66% under the same conditions. Although polymeric Pd@R
is nonporous with Brunauer-Emmett-Teller surface area (SBET)
∼
2
−1
of 8.45 m g (Figure S18), it is also larger than the surface
area of Pd@1. A possible reason for this may be that the
existence of the large-sized pillar[5]arene framework inhibits
the close stacking of the molecules. What’s more, Pd@R can
adsorb a decent amount of substrates, indicating it is a good
reaction carrier (Figures S15 and S19).
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c01752
Notes
The authors declare no competing financial interest.
In conclusion, pillar[5]arene-based [2]rotaxane was con-
structed efficiently via a multicomponent reaction through a
ACKNOWLEDGMENTS
■
We thank the National Natural Science Foundation of China
(Nos. 21801139 and 21871227), the Natural Science
Foundation of Jiangsu Province (No. BK20180942), the
Natural Science Foundation of Nantong City (JC2019087),
the project of “Six Talent Peaks in Jiangsu Province” (XCL-
85), and the project of Jiangsu Association for Science and
Technology Young Science and Technology Talents Lifting.
“
[
multicomponent reaction”. The structure of the obtained
1
2]rotaxane was characterized by various methods, such as H
1
3
NMR, C NMR, NOESY, HR-ESI-MS, and DFT calculation.
2
+
Moreover, the polymeric materials prepared from Pd and R
through the coordination interaction between the triazole
groups and Pd ions were used to catalyze the Suzuki−Miyaura
coupling reaction. Compared with Pd(NO ) and Pd@1, Pd@
0
3
2
R showed better catalytic activity and recyclability. We hope
the fusion of pillar[5]arene-based [2]rotaxane and metal ions
will expand the application in supramolecular polymeric
materials in many other areas, such as asymmetric catalysis
and organic optical materials.
REFERENCES
■
(
1) (a) Zhu, K.; Vukotic, V. N.; Noujeim, N.; Loeb, S. J.
Bis(benzimidazolium) axles and crown ether wheels: a versatile
templating pair for the formation of [2]rotaxane molecular shuttles.
Chem. Sci. 2012, 3, 3265−3271. (b) Mena-Hernando, S.; Perez, E. M.
Mechanically interlocked materials. Rotaxanes and catenanes beyond
the small molecule. Chem. Soc. Rev. 2019, 48, 5016−5032. (c) Lewis,
J. E. M.; Beer, P. D.; Loeb, S. J.; Goldup, S. M. Metal ions in the
synthesis of interlocked molecules and materials. Chem. Soc. Rev.
ASSOCIATED CONTENT
■
*
sı Supporting Information
2
(
017, 46, 2577−2591.
2) (a) Kay, E. R.; Leigh, D. A. Rise of the Molecular Machines.
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c01752.
Angew. Chem., Int. Ed. 2015, 54, 10080−10088. (b) Xue, M.; Yang, Y.;
Chi, X.; Yan, X.; Huang, F. Development of Pseudorotaxanes and
Rotaxanes: From Synthesis to Stimuli-Responsive Motions to
Applications. Chem. Rev. 2015, 115, 7398−7501. (c) Coskun, A.;
Banaszak, M.; Astumian, R. D.; Stoddart, J. F.; Grzybowski, B. A.
Great expectations: can artificial molecular machines deliver on their
promise? Chem. Soc. Rev. 2012, 41, 19−30. (d) Sauvage, J.-P.
Transition Metal-Containing Rotaxanes and Catenanes in Motion:
Toward Molecular Machines and Motors. Acc. Chem. Res. 1998, 31,
Syntheses methods of R and R@Pd, structure character-
ization, catalytic property of R@Pd (PDF)
AUTHOR INFORMATION
■
Corresponding Authors
Chaoguo Yan − School of Chemistry and Chemical Engineering,
Yangzhou University, Yangzhou, Jiangsu 225000, P. R. China;
orcid.org/0000-0002-2777-9582; Email: cgyan@
yzu.edu.cn
Yong Yao − School of Chemistry and Chemical Engineering,
Nantong University, Nantong, Jiangsu 226019, P. R. China;
orcid.org/0000-0001-5566-4822; Email: yaoyong1986@
ntu.edu.cn
6
11−619. (e) Wittenberg, J. B.; Costales, M. G.; Zavalij, P. Y.; Isaacs,
L. A clipped [3]rotaxane derived from bis-nor-seco-cucurbit[10]uril.
Chem. Commun. 2011, 47, 9420−9422. (f) Kohsaka, Y.; Koyama, Y.;
Takata, T. Graft Polyrotaxanes: A New Class of Graft Copolymers
with Mobile Graft Chains. Angew. Chem., Int. Ed. 2011, 50, 10417−
10420. (g) Arduini, A.; Bussolati, R.; Credi, A.; Faimani, G.;
Garaudee, S.; Pochini, A.; Secchi, A.; Semeraro, M.; Silvi, S.;
Venturi, M. Towards Controlling the Threading Direction of a
D
https://dx.doi.org/10.1021/acs.inorgchem.0c01752
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Communication
Calix[6]arene Wheel by Using Nonsymmetric Axles. Chem. - Eur. J.
009, 15, 3230−3242. (h) Zhao, Y. L.; Aprahamian, I.; Trabolsi, A.;
Metal Nanoparticles inside or outside of Organic Microstructures via
Self-Assembly of Resorcinarene. ACS Nano 2010, 4, 2129−2141.
(9) (a) Miyaura, N.; Yanagi, T.; Suzuki, A. The Palladium-Catalyzed
Cross-Coupling Reaction of Phenylboronic Acid with Haloarenes in
the Presence of Bases. Synth. Commun. 1981, 11, 513−519.
(b) Verma, A.; Tomar, K.; Bharadwaj, P. K. Nanosized Bispyrazole-
Based Cryptand-Stabilized Palladium(0) Nanoparticles: A Reusable
Heterogeneous Catalyst for the Suzuki-Miyaura Coupling Reaction in
Water. Inorg. Chem. 2019, 58, 1003−1006.
(10) Han, K.; Zhang, Y.; Li, J.; Yu, Y.; Jia, X.; Li, C. Binding
Mechanisms and Driving Forces for the Selective Complexation
between Pillar[5]arenes and Neutral Nitrogen Heterocyclic Com-
pounds. Eur. J. Org. Chem. 2013, 11, 2057−2060.
2
Erina, N.; Stoddart, J. F. Organogel Formation by a Cholesterol-
Stoppered Bistable [2]Rotaxane and Its Dumbbell Precursor. J. Am.
Chem. Soc. 2008, 130, 6348−6350.
(3) Zhang, C.; Li, S.; Zhang, J.; Zhu, K.; Li, N.; Huang, F. Benzo-21-
Crown-7/Secondary Dialkylammonium Salt [2]Pseudorotaxane- and
2]Rotaxane-Type Threaded Structures. Org. Lett. 2007, 9, 5553−
556.
4) (a) Ogoshi, T.; Kanai, S.; Fujinami, S.; Yamagishi, T.-a.;
[
5
(
Nakamoto, Y. para-Bridged Symmetrical Pillar[5]arenes: Their Lewis
Acid Catalyzed Synthesis and Host−Guest Property. J. Am. Chem. Soc.
2
008, 130, 5022−5023. (b) Ni, Y.; Yin, M.; Dong, S.; Huang, F.;
Zhao, Q. A poly(ionic liquid)-pillar[5]arene honeycombed isoporous
2
+
membrane for high performance Cu sensors. Appl. Surf. Sci. 2020,
00, 144056. (c) Yang, K.; Chao, S.; Zhang, F.; Pei, Y.; Pei, Z. Recent
5
advances in the development of rotaxanes and pseudorotaxanes based
on pillar[n]arenes: from construction to application. Chem. Commun.
2
019, 55, 13198−13210. (d) Kakuta, T.; Yamagishi, T.-a.; Ogoshi, T.
Stimuli-Responsive Supramolecular Assemblies Constructed from
Pillar[n]arenes. Acc. Chem. Res. 2018, 51, 1656−1666. (e) Lin, Q.;
Jiang, X.-M.; Ma, X.-Q.; Liu, J.; Yao, H.; Zhang, Y.-M.; Wei, T. B.
Novel bispillar[5]arene-based AIEgen and its’ application in mercury-
(II) detection. Sens. Actuators, B 2018, 272, 139−145. (f) Xia, D.; Lv,
X.; Chen, K.; Wang, P. A [2]pseudorotaxane based on a pillar[6]arene
and its application in the construction of a metallosupramolecular
polymer. Dalton Trans. 2019, 48, 9954−9958. (g) Wang, M.; Zhou, J.;
Li, E.; Zhou, Y.; Li, Q.; Huang, F. Separation of Monochlorotoluene
Isomers by Nonporous Adaptive Crystals of Perethylated Pillar[5]-
arene and Pillar[6]arene. J. Am. Chem. Soc. 2019, 141, 17102−17106.
(h) Sun, G.; He, Z.; Hao, M.; Xu, Z.; Hu, X.-Y.; Zhu, J.-J.; Wang, L.
Bifunctional supramolecular prodrug vesicles constructed from a
camptothecin derivative with a water-soluble pillar[5]arene for cancer
diagnosis and therapy. Chem. Commun. 2019, 55, 10892−10895.
(i) Chen, J.; Wang, Y.; Wang, C.; Long, R.; Chen, T.; Yao, Y.
Functionalization of inorganic nanomaterials with pillar[n]arenes.
Chem. Commun. 2019, 55, 6817−6826. (j) Guo, M.; Wang, X.; Zhan,
C.; Demay-Drouhard, P.; Li, W.; Du, K.; Olson, M. A.; Zuilhof, H.;
Sue, A. C.-H. Rim-Differentiated C5-Symmetric Tiara-Pillar[5]arenes.
J. Am. Chem. Soc. 2018, 140, 74−77. (k) Han, B.; Zhu, L.; Wang, X.;
Bai, M.; Jiang, J. Conformation-controlled emission of AIE
luminogen: a tetraphenylethene embedded pillar[5]arene skeleton.
Chem. Commun. 2018, 54, 837−840. (l) Ma, L.; Wang, S.; Li, C.; Cao,
D.; Li, T.; Ma, X. Photo-controlled fluorescence on/off switching of a
pseudo[3]rotaxane between an AIE-active pillar[5]arene host and a
photochromic bithienylethene guest. Chem. Commun. 2018, 54,
2
(
405−2408.
5) Strutt, N. L.; Forgan, R. S.; Spruell, J. M.; Botros, Y. Y.; Stoddart,
J. F. Monofunctionalized Pillar[5]arene as a Host for Alkanediamines.
J. Am. Chem. Soc. 2011, 133, 5668−5671.
(6) (a) Ogoshi, T.; Kotera, D.; Nishida, S.; Kakuta, T.; Yamagishi,
T.-a.; Brouwer, A. M. Spacer Length-Independent Shuttling of the
Pillar[5]arene Ring in Neutral [2]Rotaxanes. Chem. - Eur. J. 2018, 24,
6
325−6329. (b) Dong, S.; Yuan, J.; Huang, F. A pillar[5]arene/
imidazolium [2]rotaxane: solvent- and thermo-driven molecular
motions and supramolecular gel formation. Chem. Sci. 2014, 5,
2
47−252. (c) Ogoshi, T.; Yamafuji, D.; Aoki, T.; Yamagishi, T.-a.
Thermally responsive shuttling behavior of a pillar[6]arene-based
2]rotaxane. Chem. Commun. 2012, 48, 6842−6844. (d) Zeng, X.;
Deng, H.; Jia, X.; Cui, L.; Li, J.; Li, C.; Fang, J. Construction of
2]rotaxane-based supramolecular polymers driven by wheel-stopper
π-π interactions. Chem. Commun. 2018, 54, 11634−11637.
7) Cui, Y.-H.; Deng, R.; Li, Z.; Du, X.-S.; Jia, Q.; Wang, X.-H.;
[
[
(
Wang, C.-Y.; Meguellati, K.; Yang, Y.-W. Pillar[5]arene pseudo[1]-
rotaxane-based redox-responsive supramolecular vesicles for con-
trolled drug release. Mater. Chem. Front. 2019, 3, 1427−1432.
(8) (a) Li, Z. Q.; Zhang, Y.-M.; Chen, Y.; Liu, Y. A Supramolecular
Tubular Nanoreactor. Chem. - Eur. J. 2014, 20, 8566−8570. (b) Sun,
Y.; Yao, Y.; Yan, C.-G.; Han, Y.; Shen, M. Selective Decoration of
E
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