A Charge-Transfer-Induced Self-Healing Supramolecular Hydrogel

Article abstract of DOI:10.1002/asia.201601216

In this study, a dual-component charge-transfer (CT)-induced supramolecular hydrogel was fabricated using pyrene-tailored pyridinium (PYP) and 2,4,7-trinitrofluorenone (TNF) as the electron donor and acceptor, respectively. Its thermal stability and mechanical property have been modulated effectively by altering the concentration or molar ratio of PYP and TNF. Moreover, this CT hydrogel exhibited a distinct injectable self-healing property that could be utilized to create desired patterns on substrates. Such property holds potential for this CT hydrogel in fields like three-dimensional printing and surface coating.

Full text of DOI:10.1002/asia.201601216

CHEMISTRY
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Accepted Article
Title: A charge-transfer induced self-healing supramolecular hydrogel
Authors: Lei Gao; Yuxia Gao; Yuan Lin; Yong Ju; Song Yang; Jun Hu
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A charge-transfer induced self-healing supramolecular hydrogel
[
a, b]
[c]
[b]
[c]
[a]
[b]
Lei Gao,
Yuxia Gao, Yuan Lin, Yong Ju, Song Yang* and Jun Hu*
Abstract: In this research a dual-component charge-transfer (CT)
induced supramolecular hydrogel was fabricated using pyrene-
tailored pyridinium (PYP) and 2,4,7-trinitrofluorenone (TNF) as the
electron donor and acceptor, respectively. Its thermal stability and
mechanical property have been modulated effectively by altering the
concentration or molar ratio of PYP and TNF. Moreover, this CT-
hydrogel exhibited a distinct injectable self-healing property, which
could be utilized to create desired patterns on substrates. Such
property renders this CT-hydrogel potential applications in fields like
three-dimensional printing and surface coating.
considerable efforts have been devoted to creating CT-induced
[4]
assemblies. For example, Ghosh et al. demonstrated that the
electron-deficient hydrazide derivative of 1,4,5,8-naphthalene-
tetracarboxylic acid diimide (NDI) could intercalate pyrene
through CT interactions, resulting in a morphology transition
[
3a]
from vesicles to fibers, and eventually the gelation;
whereas
Maitra and co-workers reported a bile acid-tailored anthracene
CT-organogel in various solvents, which achieved the maximum
thermal and mechanical properties with the equimolar amounts
[
3b]
of the two components.
supramolecular CT-organogels have been fabricated,
research on CT-induced hydrogels are relatively less explored,
To date, although a number of
[
5]
the
[
6]
especially the injectable self-healing hydrogel. Thus, it is
necessary and beneficial to explore more CT-induced
multifunctional supramolecular hydrogels.
Introduction
Supramolecular hydrogels, consisting of three-dimensional
networks formed by molecular self-assembly to encapsulate
water, have received great attention in the past decades due to
their applications in drug delivery, protein binding and separation,
cell encapsulation, tissue engineering, wound healing,
In this research an amphiphilic pyrene-tailored pyridinium (3-
hydroxy-1-[6-(pyren-1-ylmethoxy)hexyl]pyridinium
bromide,
PYP) was synthesized as shown in Figure 1a (synthetic details
see Experimental Section), where the hydrophobic electron-rich
pyrene group and the hydrophilic 3-hydroxyl-pyridinium cation
are linked by a flexible alkyl arm. Meanwhile, the electron-
deficient 2,4,7-trinitrofluorenone (TNF) was used as the electron
acceptor to form a CT-complex with PYP, due to its importance
[
1]
optoelectronic devices, and energy harvesting.
Unlike
conventional covalent hydrogels, supramolecular hydrogels are
physically cross-linked by noncovalent interactions, which
endow them with the potential shear-thinning and self-healing
[7]
as electronic relays in electron transfer systems. Our results
[
2]
properties. In the noncovalent interactions family, charge-
transfer (CT) interactions between the electron donor (D) and
acceptor (A) are of great importance since they can modulate
the structure and mechanical properties of assemblies
effectively by altering CT-pairs, as well as their molar ratio and
demonstrated that a dual-component supramolecular hydrogel
formed primarily driven by CT interactions, in which the pyrenyl
motif of PYP and the TNF molecule adopted a slipped “face-to-
face” packing pattern, consequently resulting in the two-
dimensional (2D) microsheets (Figure 1a). Moreover, this CT-
hydrogel exhibited the distinct injectable self-healing behaviour,
which renders it potential applications in fields like three-
dimensional (3D) printing and surface coating.
[
3]
concentration. According to their stacking patterns, there are
two organizations in the CT mixed-stack, randomly entrapped
[
3h-i]
within the assembly or arranged alternatively.
Additionally,
CT-interactions could lead to stronger gels relative to the gels
derived from one of the components. Therefore, co-assembly is
favoured over individual assembly through the complexation of
D/A molecules in this type of self-organization. Inspired by this,
Results and Discussion
As a general procedure, PYP and TNF (molar ratio 1:1) were
initially mixed and heated in deionized (DI) water, Kphos buffer,
and sodium chloride aqueous solution, respectively, and
subsequently cooled to room temperature. After standing for 20
[
a]
L. Gao, Prof. S. Yang
State Key Laboratory Breeding Base of Green Pesticide &
Agricultural Bioengineering, Centre for R&D of Fine Chemicals
Guizhou University
[8]
min, the “inverted test tube method” was used to determine
whether a hydrogel formed or not, and the results were
illustrated in Table S1 and Figure S1. It showed that the stable
brownish hydrogels were obtained in DI water (entry 1, Table
S1), Kphos buffer (1 mM, pH 7.1, entry 2, Table S1), and sodium
chloride aqueous solution (10 mM, entry 6, Table S1). Either
change in pH or salt concentration resulted in the collapse of
hydrogel (entries 3, 4, 5, 7, 8, Table S1), probably due to the
protonation/ deprotonation of hydroxyl group of PYP, or the
salting out effect. Notably, TNF has the poor solubility in water
even at high temperature, whereas a significant increase in
solubility of TNF was observed with the appearance of a
brownish color after complexing with PYP (Figure 1a and S1),
Guiyang, 550025, China
E-mail: jhzx.msm@gmail.com
L. Gao, Dr. Y. Lin, Dr. J. Hu
State Key Lab of Polymer Physics and Chemistry, Changchun
Institute of Applied Chemistry, Chinese Academy of Sciences
Changchun, 130022, China
E-mail: jhu@ciac.ac.cn
Y. Gao, Prof. Y. Ju
Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical
Biology, Ministry of Education Institute of Applied Chemistry,
Department of Chemistry, Tsinghua University
Beijing, 100084, China
Supporting information for this article is given via a link at the end of
the document.
[
[
b]
c]
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which strongly revealed the existence of CT interactions. In the
following study, DI water was chosen as the solvent for the
preparation of this CT-hydrogel.
As a crucial factor to estimate the hydrogel stability, Tgel of
PYP/TNF (1:1, molar ratio) hydrogel under different
concentrations was investigated. As shown in Figure S2, Tgel
o
increased from 65 to 86 C with the concentration of PYP from 5
to 9 mg/mL. Based on the relationship between Tgel and
concentration, thermodynamic parameters at 298 K (ΔH, ΔS,
ΔG) were calculated as shown in Figure S3. The unfavourable
-1
gel to sol process (ΔG = 29 kJ mol ) indicated the excellent
stability of this CT-hydrogel. Moreover, the thermal stability of
these CT-hydrogels as
performed with the consistent concentration of PYP ([PYP] vs.
TNF], 1:0.5, 1:0.7, 1:1, 1:1.5, 1:2). As shown in Table S2, Tgel
a function of stoichiometry was
[
increased with the amount of TNF in CT-hydrogels, and reached
a maximum value at 1:1. Conversely, the excess TNF more than
1:1 caused a hydrogel collapse.
Figure 2. a) UV-Vis spectra of PYP aqueous solution in the presence and
absence of TNF. b) Temperature-dependent UV-Vis spectra of PYP/TNF (1:1,
molar ratio) complex. Inset: the visible color change from colorless to light
brownish. c) Fluorescence spectra of PYP aqueous solution in presence and
absence of TNF. d) Temperature-dependent fluorescence spectra of PYP/TNF
(1:1, molar ratio) complex. Conc. of PYP = 0.1 mM, λex = 350 nm.
The obvious color change during the gelation process
prompted us to study the driving forces of this hydrogel by UV-
Vis and fluorescent spectroscopy. In comparison with PYP a
new broad absorption band at 550 nm appeared upon
complexation with TNF (Figure 2a), which clearly indicated the
[
9]
formation of CT-complex.
The change in CT band with
temperature was monitored in the temperature-dependent UV-
Vis experiment. As seen from Figure 2b, the intensity of CT
band at 550 nm increased gradually with the temperature
decrease, companied by the visible color change from colorless
to light brownish (Figure 2b, inset). This was supported by their
fluorescence spectra, where an obvious decrease in the
intensity of PYP occurred upon addition of TNF (Figure 2c). In
addition, variable temperature fluorescence of PYP/TNF CT-
complex showed that the emission intensity was significantly
increased in high-temperature state on account of the
dissociation of CT-complex (Figure 2d), which further confirmed
the formation of CT-complex between the pyrenyl motif of PYP
and the TNF molecule.
Figure 1. a) Schematic representation of the formation of CT-induced
supramolecular hydrogel based on PYP and TNF. SEM b), TEM c), and AFM
d) images of PYP/TNF CT-hydrogel (1:1 molar ratio, conc. of PYP = 5 mg/mL).
Scale bars are 1 μm for b), 2 μm for c), and 500 nm for d), respectively.
Morphologies of microscopic structures within CT-hydrogels
were evaluated by scanning electron microscopy (SEM),
transmission electron microscopy (TEM), and atomic force
microscopy (AFM). As shown in Figure 1b and 1c, 2D sheets
were observed with lateral dimensions in several micrometres.
AFM image and height profile analysis revealed the height of 2D
microsheets was close to ca. 2.6~3.5 nm (Figure 1d and S4).
These thin 2D microsheets further stacked into 3D environments
to trap water, consequently resulting in the formation of
supramolecular hydrogel.
To obtain a better insight into CT interactions, temperature-
1
dependent H NMR experiments of PYP/TNF (1:1, molar ratio)
complex were performed. As shown in Figure 3a, all resonances
of aromatic protons on the pyrenyl moiety (H
1 9 a
-H ) and TNF (H -
H
d
) shifted upfield as the temperature decreased from 90 to 30
o
C, clearly indicating the formation of CT-complex. Due to the
pyrenyl group of PYP and the TNF molecule were mutually
experiencing the shielding from the aromatic π-clouds, their
organization was possible only in “face-to-face” (mixed CT)
manner.
group and H
other protons (Δδ H
Table S3), which revealed that TNF was oriented on π-surface
[
10]
It should be noted that protons of H
, H at TNF molecule exhibited larger shifts than
0.23 ppm, H 0.20 ppm, H 0.24 ppm,
7
at the pyrenyl
a
e
7
a
e
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of the pyrenyl group in such a way that H
shielded than others.
a
and H
e
was more
molecule promotes a slipped “face-to-face” packing pattern with
overlapped D-A pairs located at the core and a fully extended
alkyl spacer at the edge, which consequently results in the
formation of 2D microsheets (Figure 1a). Notably, it is still
difficult to predict whether TNF molecules were randomly
entrapped within the assembly or arranged alternatively with
[
12]
PYP units.
In terms of practical applications it is important to determine
the rheological parameters of soft materials. Rheological studies
could provide direct information on the fluidity and rigidity of
viscoelastic materials. To examine the present PYP/TNF CT-
hydrogel system oscillatory frequency sweep experiments were
carried out. As shown in Figure 4a, the storage modulus G’ was
greater than the respective loss modulus G”, and invariant to the
frequency under an applied strain of 2% in the frequency range
of 0.1-100 rad/s, which revealed the viscoelastic nature of this
[
13]
CT-hydrogel over the entire angular frequency range.
Moreover, the highest G’ was obtained when PYP and TNF
were mixed at a molar ratio of 1:1, ascribing to the highest
[
14]
complexation density at 1:1.
When either PYP or TNF was
present in excess, a decrease in G’ was observed (excess TNF
led to a collapse of CT-hydrogel directly), which was consistent
with the tendency of Tgel-sol data. It clearly suggested that the
viscoelastic behaviour of this CT-hydrogel could be controlled by
altering the molar ratio of the electron donor and acceptor. In
addition, the G’ value progressively increased with the increase
in gelator concentration from 6 to 10 mg/mL at [PYP]/[TNF] = 1:1
(
Figure 4b), revealing the gradual increase in viscoelasticity.
Meanwhile, it was found that after transforming into sol by
shaking, this PYP/TNF CT-hydrogel could turn back into a
robust gel on resting, indicating the self-healing property. Such
self-healing behaviour has been confirmed by the strain
amplitude sweep and the alternate step strain experiments. As
shown in Figure 4c, under the strain from 0.1% to 70%, G’ was
larger than G’’, suggesting that the hydrogel networks were stiff
and the CT complexation remained undamaged. With G’ and G’’
curves crossed, a gel-sol transition point occurred at the strain of
1
Figure 3. a) Temperature-dependent H NMR spectra of PYP/TNF (1:1, molar
2 6
ratio) complex in DMSO/D O (2:1, v/v, 400 MHz). Conc. of PYP = 6 mM, *d -
DMSO. b) X-ray diffraction profile of PYP/TNF (1:1, molar ratio) CT-xerogel. c)
Theoretical optimized structure of PYP/TNF complex. Carbon atoms,
hydrogen atoms, oxygen atoms, nitrogen, and bromide are presented in gray,
light gray, red, blue, and brown, respectively.
7
8%, which implied the beginning of hydrogel networks
In order to elucidate the molecular packing mode of the
gelator in this 3D gel network, X-ray diffraction (XRD) and
theoretical computation were carried out. Three distinct Bragg
reflection peaks at 2ϴ = 2.65°, 7.80°, and 10.35° were detected
destruction due to the disruption of CT interactions at such
[15]
strain. According to the above results of strain sweep, the self-
healable capacity of PYP/TNF CT-hydrogel was verified by the
alternate step strain test (strain = 2 and 160%) with fixing the
applied frequency at 10 rad/s throughout the experiment as
shown in Figure 4d. Initially, 2% strain was applied to the CT-
hydrogel, at which G’ showed a higher value than G’’ indicating
the distinct gel characteristic. Subsequently, 160% strain was
applied to the CT-hydrogel, and resulted in a drastic decrease of
G’ below G’’ value, demonstrating that the gel behaviour was
completely destroyed while sol behaviour was prominent.
Whereas after removing the high strain and applying a constant
strain of 2% again, the original mechanical strength of the CT-
hydrogel was fully recovered, leading to a sol-to-gel transition.
Obviously, the large strain (160%) caused the destruction of CT-
complex, resulting in the hydrogel collapse and the drastic
decrease in G’ value, while a small strain (2%) could exert a
force that helped the remixing of D/A molecules to reconstruct
the CT-complex, thus leading to reforming the hydrogel inner
(
Figure 3b), corresponding to d-spacing of 3.33, 1.13, and 0.85
nm, respectively. The ratio of these reflection peaks (1: 1/3: 1/4)
indicated the presence of ordered lamellar structures in the gel
network with a repetitive period of 3.33 nm. Considering that the
extend dimeric length of PYP/TNF complex is between 2.07 nm
(
the single complex molecular length) and 3.39 nm (the dimer
complex length with an overlap on aromatic area) based on the
assumption that the alkyl spacer takes fully extended
a
conformation (optimized by Gaussian 09 B3LYP/6-31G*), the
distance of 3.33 nm corresponds nicely to the length of
PYP/TNF complex dimer in partial overlapped π-stacked
manner with sequestering the hydrophobic pyrenyl units and
TNF rings within the interior and projecting the hydrophilic
[
11]
pyridinium cations outside (Figure 3c).
Based on above
results, it is concluded that the CT interactions between the
electron-rich pyrenyl motif of PYP and the electron-deficient TNF
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network. The self-recovery experiment was repeated four times Experimental Section
in a cycle, and in each case the stiffness could be recovered
within a time interval of 180 seconds. This alternate step strain
results strongly indicated the self-healing property of PYP/TNF
General Materials: 1-Pyrenylmethanol was purchased from J&K
Chemical LTD. 1,6-Dibromohexane was purchased from Shanghai
Aladdin Bio-Chem Technology Co. LTD. 3-Hydroxypyridine was
purchased from Heowns Biochem Technologies LLC. TianJin. Other
common chemicals were from local commercial suppliers.
Tetrahydrofuran was dried with calcium hydride before the use.
(
1:1, molar ratio) CT-hydrogel, which made it suitable to be
utilized as an injectable material. As shown in Figure 4e, the
PYP/TNF (1:1, molar ratio) CT-hydrogel could easily be
transferred into a syringe and extruded to create desired
patterns on the substrate, which may make this hydrogel to
fabricate complex structures by 3D printing.
1
13
Characterization: H and C NMR spectra were recorded on JEOL
o
3 6
JNM-ECA 400 spectrometer in CDCl or d -DMSO at 25 C. Electrospray
ionization mass (ESI-MS) was analyzed on Bruker ESQUIRE-LC
spectrometer in positive mode. High-resolution mass spectrometry
(
(
HRMS) was measured in positive mode using quadrupole time-of-flight
Q-TOF) as mass analyzer. UV-Vis spectra were recorded on
NANODROP
2000C
spectrophotometer,
and
fluorescence
measurements were carried out on Luminescence Spectrometer 50B
from PerkinElmer instruments. Transmission Electron Microscopy (TEM)
was recorded on a JEOL JEM-1011 electron microscope operating at an
acceleration voltage of 100 kV. Atomic Force Microscopy (AFM)
measurements were performed on a NanoScope 3D AFM (Veeco, USA)
using the tapping mode with a SiN
Electron Microscopy (SEM) was recorded on
4
tip (radius of 10~20 nm). Scanning
a
Hitachi S-4800
microscope operating at 10-15 kV. Rheological experiments were
performed in a plate geometry (diameter 25 mm) on the rheometer plate
using a TA Instrument. X-ray diffraction was analyzed using a Bruker D8
Advance instrument. The X-ray beam generated with rotating Cu anode
at the wavelength of KR beam at 1.5418 Ǻ was directed toward the film
edge and scanning was done up to a 2θ value of 45°. Data were
analyzed and interpreted using the Bragg equation. Quantum chemistry
computations were performed using the B3LYP density functional theory
(DFT) with Gaussian09 suite of programs. The structure was optimized
by employing the 6-31G(d,p)* basis set in the gas phase.
Synthesis of PYB: 1-Pyrenylmethanol (1.00 g, 4.31 mmol) and sodium
hydride (NaH, 1.03 g, 43.05 mmol) were dissolved in 15 mL dry
tetrahydrofuran (THF), and then 1,6-dibromohexane (3.48 mL, 21.53
mmol) was added. The mixture was refluxed for 2 h under nitrogen
atmosphere, and afterwards the excess NaH was quenched by addition
of ethanol and water. The mixture was concentrated under reduced
Figure 4. Oscillatory frequency sweep of PYP/TNF CT-hydrogel with a)
different molar ratio of PYP/TNF (conc. of PYP = 8 mg/mL), and b) different
concentrations (1:1, molar ratio). c) G’ and G’’ of PYP/TNF CT-hydrogel (1:1, 8
mg/mL) as a function of strain (0.1 - 200%). d) G’ and G’’ of PYP/TNF CT-
hydrogel (1:1, 8 mg/mL) in alternate step strain measurements (25 C). e) The
sol-gel transition on resting and its injectability of PYP/TNF (1:1, molar ratio,
conc. of PYP = 8 mg/mL) CT-hydrogel.
o
pressure, and the aqueous phase was extracted with CH
The organic phases were then collected, washed with water, dried with
anhydrous sodium sulfate (Na SO ), filtered, concentrated under reduced
pressure, and purified by column chromatography (hexane/ethyl acetate
2 2
Cl (3 × 15 mL).
2
4
Conclusions
3
0:1, v/v) to give a faint yellow solid, PYB (1.45 g, yield 85%). ESI-MS (+):
+
+
419 [M + Na] ; ESI-HRMS (+): C23
H23BrO calc. 419.0807 [M + Na] ,
In conclusion, a dual-component CT-induced supramolecular
hydrogel was fabricated using pyrene-tailored pyridinium PYP
and TNF as the electron donor and acceptor, respectively.
Within this 3D hydrogel networks, the CT interactions primarily
promoted a slipped “face-to-face” packing pattern between the
1
found 419.0809; H NMR (400 MHz, CDCl
3
, ppm): δ 8.39 (d, 1H, J = 8.0
Hz, pyrene-H), 8.22 (m, 4H, pyrene-H), 8.06 (m, 4H, pyrene-H), 5.22 (s,
H, pyrenyl-CH O-), 3.61 (t, 2H, J = 6.0 Hz, -OCH -), 3.34 (t, 2H, J = 6.0
Br), 1.81 (m, 2H, CH ), 1.67 (m, 2H, CH ), 1.41 (m, 4H, CH );
, ppm): δ 131.87, 131.40, 131.39, 130.98,
2
2
2
Hz, -CH
C NMR (100 MHz, CDCl
2
2
2
2
13
3
electron-rich pyrenyl motif of PYP and the electron-deficient TNF, 129.50, 127.76, 127.56, 127.50, 127.06, 126.06, 125.33, 125.10, 124.90,
1
24.62, 123.64 (16C, pyrene-C), 71.69 (pyrenyl-CH
2 2
O), 70.35 (OCH ),
thus resulting in the formation of 2D microsheets. Moreover, its
thermal stability and mechanical property could be modulated
effectively by altering the concentration or molar ratio of PYP
and TNF. Additionally, this CT-hydrogel exhibited a distinct
injectable self-healing property, and could be utilized to create
desired patterns on substrates, which strongly renders this CT-
hydrogel potential applications such as 3D printing and surface
coating.
33.97 (CH Br), 32.87, 29.79, 28.07, 25.58 (4C, CH ).
2
2
Synthesis of PYP: 3-Hydroxypyridine (289 mg, 3.03 mmol) was added
to 5 mL N,N-dimethylformamide solution of PYB (600 mg, 1.51 mmol),
and then the mixture was stirred at 100 C for 5 h. After removing the
solvent under reduced pressure, the residue was purified by column
chromatography (dichloromethane/methanol 5:1, v/v) to afford a faint
o
+
yellow solid, PYP (695 mg, yield 93%). ESI-MS (+): 410 [M] ; ESI-HRMS
+
1
(
d
+): C28
-DMSO, ppm): δ 8.46 (m, 11H, pyrene-H, pyridine-H), 7.83 (m, 2H,
pyridine-H), 5.16 (s, 2H, pyrenyl-CH O-), 4.38 (t, 2H, J = 8.0 Hz, -CH N-),
2
H28NO calc. 410.2120 [M] , found 410.2122; H NMR (400 MHz,
6
2
2
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3
.56 (t, 2H, J = 6.0 Hz, -OCH
2
-), 1.81 (m, 2H, CH
2
), 1.57 (m, 2H, CH
2
),
1632; f) O. D. Parashchuk, T. V. Laptinskaya, D. Y. Paraschuk, Phys.
Chem. Chem. Phys. 2011, 13, 3775-3781; g) Y. Liu, Y. Yu, J. Gao, Z.
Wang, X. Zhang, Angew. Chem. Int. Ed. 2010, 49, 6576-6579; Angew.
Chem. 2010, 122, 6726-6729; h) H. Y. Au-Yeung, G. D. Pantos, J. K. M.
Sanders, Angew. Chem. Int. Ed. 2010, 49, 5331-5334; Angew. Chem.
2010,122, 5459-5462; i) N. S. S. Kumar, M. D. Gujrati, J. N. Wilson,
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Wang, Z. Li, X. Zhang, Langmuir 2012, 28, 10697-10702.
13
1.35 (m, 2H, CH ), 1.23 (m, 2H, CH
2
2
); C NMR (100 MHz, d -DMSO,
6
ppm): δ 133.03, 132.16, 131.48, 130.74, 130.55, 130.29, 128.63, 128.14,
127.47, 127.39, 127.26, 126.97, 126.30, 125.33, 125.26, 124.58, 124.00,
123.86, 123.59 (16C, pyrene-C; 5C, pyridine-C), 70.37 (pyrenyl-CH O),
69.61 (CH N), 60.42 (OCH ), 30.61, 29.02, 25.23 (4C, CH ).
2
2
2
2
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5]
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Acknowledgements
This work is supported by NSFC (No. 21604085, 21429401,
2
2
1374119), Jilin Science Foundation for Youths (No.
0160520135JH), and Open Research Fund of State Key
Laboratory of Polymer Physics and Chemistry, CIAC.
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Keywords: charge-transfer • hydrogel • self-healing • pyrene •
trinitrofluorenone
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For internal use, please do not delete. Submitted_Manuscript
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Chemistry - An Asian Journal
10.1002/asia.201601216
FULL PAPER
Layout 2:
FULL PAPER
Lei Gao, Yuxia Gao, Yuan Lin, Yong
Ju, Song Yang* and Jun Hu*
Page 1 – Page 4
A charge-transfer induced self-
healing supramolecular hydrogel
A dual-component CT-induced supramolecular hydrogel was fabricated, using
pyrene-tailored pyridinium (PYP) and 2, 4, 7-trinitrofluorenone (TNF) as the
electron donor and acceptor, respectively. Within this CT-hydrogel the pyrenyl
motif of PYP and the TNF molecule primarily promoted a slipped “face-to-face”
packing pattern, consequently resulting in the 2D microsheets. Moreover, this
CT-hydrogel exhibited a distinct injectable self-healing property, which could be
utilized to create desired patterns on substrates. Such property strongly renders
this CT-hydrogel potential applications in fields like 3D printing and surface
coating.
For internal use, please do not delete. Submitted_Manuscript
This article is protected by copyright. All rights reserved