Self-assembly of azobenzene-based two-component gels

Article abstract of DOI:10.1039/c4nj01131g

An azobenzene derivative was found to form a two-component gelator with lauroyl or stearoyl phenylalanine although phenylalanine units failed to gel the solvent. During gelation, the yellow sols turned into red gels, implying a sharp color change in the system. In gel, molecules self-assembled into one-dimensional nanofibers. Circular dichroism spectral results indicated that the chirality of phenylalanine was passed on to the azobenzene moiety, which formed a right-handed helical stacking in the gel phase. UV-vis experiments and NMR spectra revealed that the azobenzene derivative and lauroyl phenylalanine formed a complex with a ratio of 1:4. The critical gelation concentrations and gel-to-sol phase transition temperatures were dependent on the ratio of the two compounds. Moreover, the response of two-component gels to mechanical stimulus could result in a gel-to-sol transition. The gels can again self-heal after resting, which is a process that can be reversed numerous times. This journal is

Full text of DOI:10.1039/c4nj01131g

NJC
View Article Online
View Journal
PAPER
Self-assembly of azobenzene-based
two-component gels†
Cite this:DOI: 10.1039/c4nj01131g
a
b
b
b
Yuan Zhang, Pengchong Xue,* Boqi Yao and Jiabao Sun
An azobenzene derivative was found to form
a two-component gelator with lauroyl or stearoyl
phenylalanine although phenylalanine units failed to gel the solvent. During gelation, the yellow sols turned
into red gels, implying a sharp color change in the system. In gel, molecules self-assembled into one-
dimensional nanofibers. Circular dichroism spectral results indicated that the chirality of phenylalanine was
passed on to the azobenzene moiety, which formed a right-handed helical stacking in the gel phase. UV-vis
experiments and NMR spectra revealed that the azobenzene derivative and lauroyl phenylalanine formed a
Received (in Montpellier, France)
8th July 2014,
Accepted 7th August 2014
complex with
a ratio of 1 : 4. The critical gelation concentrations and gel-to-sol phase transition
temperatures were dependent on the ratio of the two compounds. Moreover, the response of two-
component gels to mechanical stimulus could result in a gel-to-sol transition. The gels can again self-heal
after resting, which is a process that can be reversed numerous times.
DOI: 10.1039/c4nj01131g
www.rsc.org/njc
Smith discovered numerous two-component dendritic gels, the
Introduction
properties and morphologies of which can be controlled by com-
8
Non-covalent interactions are effective tools for constructing ponents. Shinkai found that fullerene can form a one-dimensional
well-defined supramolecular structures driven by molecular self- multicapsular structure with a tetraphenylporphyrin derivative,
1
9
assembly, which generally determine material properties. Consider- after which a gel phase was observed. Yi, Fang, Ajayaghosh, and
able interest has been directed toward these interactions for the Meijer et al. also developed numerous functional two-component
10
development of novel gel-phase materials on the basis of low- organogels. Some useful two-component gels have recently been
2
molecular-mass gelators. The self-assembly process facilitates investigated by our group, and have been used in temperature-
the formation of supramolecular polymer-like structures through controlled fluorescence switches, chemosensors for volatile acids,
intermolecular non-covalent interactions (i.e., van der Waals, p–p, and organic amines and for photocurrent generation in electronic
11
hydrogen bonding, electrostatic, coordination, and charge-transfer donor–acceptor gels.
interactions). Organogels are jelly-like soft materials that are gen- In this study, we found that an azobenzene derivative (PDNA)
erally composed of a one-component gelator and a large amount of can aid lauroyl or stearoyl phenylalanine (C12Ph and C18Ph) to gel
solvent. To achieve unique properties in the gel phase, a simple hexane, octane, and cyclohexane even when phenylalanine units
method is to introduce functional moieties into the molecular fail to gel these solvents. In gel, molecules self-assembled into one-
structure through a covalent bond. So far, one-component gels dimensional nanofibers. Results of the circular dichroism (CD)
3
4
have been useful in photovoltaics, field-effect transistors,
spectra indicated that the chirality of phenylalanine was passed on
to the azobenzene moiety, which formed a right-handed helical
5
6
sensors, and various stimuli-responsive materials, and so on.
Two-component gels composed of two compounds have stacking in the gel phase. Moreover, the critical gelation concen-
7
recently been developed. A functional moiety can be easily intro- tration (CGC) and gel-to-sol phase transition temperatures (Tgel
)
duced by non-covalent bonds, and the properties of two-component depended on the ratio of these two components. The response
gels can be controlled by adjusting the ratio of two components. of these gels to mechanical stimulus could result in a gel-to-sol
transition. The gels could self-heal after resting, which is a
a
process that can be reversed numerous times.
Key Laboratory of Theoretical and Computational Photochemistry, Ministry of
Education, College of Chemistry, Beijing Normal University, 19# XinJieKouWai St.,
HaiDian District, Beijing, P. R. China
b
State Key Laboratory of Supramolecular Structure and Materials,
College of Chemistry, Jilin University, 2699# Qianjin Street, Changchun,
P. R. China. E-mail: xuepengchong@jlu.edu.cn
Results and discussion
1
Three compounds were easily synthesized by classical methods
†
Electronic supplementary information (ESI) available: H NMR spectra, rheo-
(
Scheme 1) and characterized by NMR, IR, MS and elemental
metry data, IR spectra and SEM images of complexes, and absorption spectra of
complexes (3 : 1) at different concentrations. See DOI: 10.1039/c4nj01131g
analysis. For detailed procedures see Experimental section.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
0
measurements. The strength (storage modulus, G ) of the gel is
more than 6500 pa with a small strain of 0.01% when the
ꢀ
1
0
00
concentration was 1.0 mg mL . G and the loss modulus (G )
0
00
remained nearly constant up to 3% and G was greater than G of
the gel (Fig. S4, ESI†). This result suggests that cyclohexane is stable
because of the presence of a 3D fibrous network.
A sharp color change was observed during gelation. UV-vis
spectra were used to monitor the gelation process. The absorp-
tion peak at 415 nm in the hot cyclohexane solution gradually
decreased when the solution was cooled (Fig. 3a). Meanwhile, a
Scheme 1 Synthesis routes of C12Ph, C18Ph, and PDNA.
Fig. 1 Mixtures of PDNA and C12Ph in a ratio of 1 : 1 in cyclohexane.
First, the mixture of PDNA and C12Ph in a 1 : 1 molar ratio was
prepared by mixing the two compounds in CH Cl and then
2
2
removing the solvent. The CH Cl solution was yellow, whereas the
2
2
solid changed to dark red, indicating that PDNA formed aggregates
12
in the solid state. This red mixture was dissolved in cyclohexane,
hexane, and octane to form a clear yellow solution upon heating,
and then transformed into red gels upon cooling (Fig. 1). Under the
same conditions, C12Ph formed white precipitation in these solvents
11b
despite containing amide and the long alkyl chain. The mixture of
PDNA and C18Ph (1 : 1) can also form a red gel in these solvents.
Therefore, PDNA can help C12ph to gel the solvent.
The light microscopy image (Fig. 2a) of the cyclohexane gel
illustrates that the mixture of PDNA and C12Ph (1 : 1) prefers to
self-assemble and form long and thin fibers. A fibrous network
structure is also formed by intertwining fibers. A scanning electron
microscope (SEM) was used further to study the microscopic
structure of the gels. An extended fibrillar network was observed
(Fig. 2b). Thus, the mixture is likely to self-assemble into a one-
dimensional fiber. The gel stability was studied by rheological
Fig. 3 UV-vis spectral change of C12Ph and PDNA with different molar
ratios of 1 : 1 (a), 3 : 1 (b), and 4 : 1 (c) during gelation (from 80 to 10 1C, at an
interval of temperature is 5 1C) in cyclohexane. Concentration of three
Fig. 2 (a) Optical microscopy images and (b) SEM images of the cyclo-
hexane gel formed by C12Ph and PNDA (1 : 1).
ꢀ1
samples is 1.8 mg mL . The optical path is 0.2 mm.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
new peak at 500 nm with a shoulder peak at 555 nm appeared
Accordingly, C12Ph and PDNA form the hydrogen bond
and gradually increased. The appearance of two new peaks complex in a ratio of 4 : 1. The gel properties are possibly
suggests why the gel is red and implies that PDNA self- dependent on the components of the two compounds. It was
1
3
assembled into J-aggregates. Thus, the exciton coupling exists found that the microstructures of gels with different molar
between PDNA molecules. ratios were similar. For example, the gels (3 : 1 and 4 : 1) were
The 415 nm absorption peak did not disappear and was comprised of thin and long fibers (Fig. S7, ESI†). This result
stronger than that at 500 nm, thus indicating that many PDNA suggests that microstructures of gels are independent of the
molecules exist in the monomeric state in the gel of the mixture components of gels. This case is different from that reported by
(
1 : 1). Such a result can be confirmed by the following experi- Smith, in which morphologies of gels are strongly affected by
8
e
ment. The gel was first destroyed through mechanical stirring. the ratio of two components. When the ratio of C12Ph and
Clear yellow solution and red solid were obtained by centrifu- PDNA was 3 : 1, the absorption peak at 415 nm decreased, and
gation, and their absorption spectra were recorded. The clear the peak at 500 nm was enhanced (Fig. 3b). In the complex gel
yellow solution has an absorption band with a maximal peak of with a 4 : 1 ratio, the monomeric absorption band disappeared
415 nm, and its absorbance is almost the same as that of the (Fig. 3c), thus indicating that all PDNA molecules formed
wet gel (Fig. 4). The absorption band of the red solid is similar aggregates. The concentration-dependent UV-vis spectra of
to that of the new peak at 500 nm in the wet gel. This result the complex (4 : 1) are shown in Fig. S8 (ESI†). At high concen-
affirms that a large amount of PDNA did not aggregate in the trations, the absorption band of the monomeric state cannot be
1
gel mixture (1 : 1). The H NMR spectrum of red solid obtained found. When concentration decreases, the absorbance at
in the wet gel suggests that the molar ratio of C12Ph and PDNA around 400 nm gradually increases, and the absorption band
is 4 : 1 in red solid (Fig. S5, ESI†). That is, C12Ph and PDNA at 500 nm becomes weaker. When the concentration reaches
ꢀ
1
formed a complex with a molar ratio of 4 : 1, not 1 : 1, which differs 0.003 mg mL , the peak at 500 nm vanishes, and only an
from that of hydrogen-bonded two-component gels previously absorption band at 415 nm remains. Hence, the aggregation
14
1
reported. Small shifts of PDNA protons in the H NMR spectrum degree of PDNA is correlated with concentration.
of the red solid may imply the hydrogen-bonded complex formed The component of the two compounds determined their
by C12Ph and PDNA rather than a hydrogen-bonded ion pair. CGCs, as shown in Fig. 5. The equimolar mixture of PDNA and
ꢀ
1
The infrared (IR) spectra also suggest the same result. C12Ph in C12Ph in cyclohexane had a CGC of 1.4 mg mL . When the
ꢀ
1
the solid state has a strong IR absorption peak at 1707 cm
,
molar ratio of C12Ph and PDNA increased to 3 : 1, CGC
15
ꢀ1
indicating a dimer structure of carboxylic acid groups. The red decreased to 0.8 mg mL . The complex of 4 : 1 had the smallest
solid possessed a weak and wide peak at 1705 cm with a CGC (0.74 mg mL ). The excess PDNA molecules existing in the
shoulder peak at 1715 cm (Fig. S6, ESI†). These results suggest solution of equimolar mixture may be responsible for the high
a hydrogen-bonded complex. Moreover, the vibration absorption CGC. Moreover, the CGCs of C18Ph and PDNA mixtures are
peaks of NH and amide I appeared at 3306 and 1646 cm, associated with the component of two compounds (Fig. 5). For
respectively, indicating the formation of intermolecular hydrogen example, 1 mL of cyclohexane requires an equimolar mixture of
bonds between amide units in the gel. As suggested by NMR 20 mg for gelation. The CGC of the complex of 4 : 1 decreased to
spectra, the hydrogen bonded complex in CDCl solution existed 4 mg mL . The mixture of C18Ph and PDNA clearly exhibited a
ꢀ
1
ꢀ1
ꢀ1
16
17
ꢀ1
3
and its color was yellow, indicating that the color change during higher CGC than those of C12Ph and PDNA at the same molar
gelation is ascribed to p–p interaction between PDNA molecules, ratio. C18Ph demonstrates higher solubility than C12Ph in
18
rather than the charge transfer complex.
cyclohexane, which may explain the difference in CGC.
Fig. 4 UV-vis spectra of the mixture of PDNA and C12Ph in a 1 : 1 ratio in
Fig. 5 Critical gelation concentration of the mixtures with different molar
hot solution and gel, and the solution and dried gel after centrifugation.
ratios.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
Fig. 7 Circular dichroism and UV-vis absorption spectra of the gel (4 : 1) in
ꢀ1
cyclohexane at 1.0 mg mL concentration.
Fig. 6
Tgels of cyclohexane gels of C12Ph/PDNA vs. concentration.
The CGCs of gels are found to depend on their components.
Thus, gel components can also determine Tgels. Fig. 6 shows the
relationship between Tgels and concentration. Tgels of all gels
increase as gelator concentration increases. For instance, the gel
ꢀ1
of C12Ph and PDNA (1 : 1) at a concentration of 1.6 mg mL
transformed into a sol at 41 1C. When the concentration increased
ꢀ1
to 3.5 mg mL , Tgel reached 52 1C. As the amount of C12Ph
increased, the corresponding Tgel also improved. The gels of the
complex (4 : 1) exhibited the highest Tgels at the same concen-
ꢀ
1
tration. At a 3.5 mg mL concentration, high temperature (66 1C) Fig. 8 Photos of the complex (4 : 1) in cyclohexane.
was required for gel–sol transformation. This temperature was
higher than that (52 1C) of the gel (1 : 1) at the same concentration.
Gels also exhibited thixotropic behavior. When we applied
This result is similar to that in CGC observation and indicates that
the complex (4 : 1) is an optimal two-component gelator relative to
other two mixtures.
external mechanical stress, such as shaking and stirring, the cyclo-
hexane gel of the complex (4 : 1) lost its viscosity and transformed
23
into a sol (Fig. 8). After resting for almost 1 h at room temperature,
the gel could be recovered. The self-healing process after the gel-
to-sol transition can be repeated many times. The self-healing time
of the destroyed gel is inversely proportional to its concen-
The thermodynamic parameters (DH1, DS1) associated with the
sol–gel phase transition can be obtained by using the van’t Hoff
method that plots ln(C) against 1/T. DH1 and DS1 were determined
ꢀ
1
ꢀ1 ꢀ1
19
to be ꢀ44.9 kJ mol and ꢀ95.6 J mol
K , respectively. The
ꢀ
1
ꢀ
1
tration. At a concentration of 5 mg mL , the sol can change
into a gel after 5 min. The two-component gel containing
C18Ph and PDNA also possesses thixotropic activity.
Gibbs free-energy change DG was calculated to be ꢀ16.4 kJ mol
,
indicating the occurrence of spontaneous gel formation.
Owing to the occurrence of exciton coupling between PDNA
molecules and molecular chirality of C12Ph, CD spectroscopy
may be an appropriate method for further studying the assem-
bly process. Strong bisignated-induced CD bands (the positive
Conclusions
cotton effect) were found in the 475 nm to 650 nm region An azobenzene derivative can aid lauroyl or stearoyl phenylalanine to
max = 524 nm, lmin = 480 nm, ly=0 = 500 nm, Fig. 7). PDNA is form two-component gels. During gelation, the yellow sols turned
not a chiral molecule. Thus, CD signals are induced by the into red gels, and molecules self-assembled into one-dimensional
(l
2
0
chiral packing of PDNA. The positive cotton effect implies a nanofibers. Circular dichroism spectral results indicated that the
2
1
right-handed helical aggregate in the gel. Such a chiral chirality of phenylalanine was passed on to the azobenzene moiety,
packing of PDNA in gel is obviously caused by the chirality of which formed a right-handed helical stacking in the gel phase. The
C12Ph. As the temperature increased to 40 1C, CD intensity spectral results suggested that the molar ratio of the azobenzene
decreased, indicating that some PDNA molecules broke away derivative and lauroyl phenylalanine in gel fibers is 1 : 4. Moreover,
from the aggregate. When the temperature increased to 60 1C, the UV-vis spectra, critical gelation concentration, and T s were
gel
at which point the red gel changed into the yellow sol, no found to be dependent on the ratio of two compounds. Interestingly,
detectable CD was observed. These findings further reflect that the two-component gels exhibited outstanding self-healing proper-
the CD signals in the visible region in the gel can indeed be ties after being destroyed by vigorous shaking or stirring. These gels
2
2
attributed to molecular aggregates of PDNA.
are considered as useful materials for further applications.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
Experimental section
Instruments
6.8, 1.1 Hz, 1H), 7.56 (ddd, J = 8.3, 6.8, 1.1 Hz, 1H), 7.53
(
(
tt, J = 8.0, 1.6 Hz, 2H), 7.43 (tt, J = 7.3, 1.3 Hz, 1H), 6.83
d, J = 8.3 Hz, 1H), 4.6 (s, 2H). MALDI-TOF MS: m/z: calcd for
Infrared spectra were recorded using a Nicolet-360 FT-IR
spectrometer by incorporating the samples in KBr disks. The
UV-vis absorption spectra were determined on a Mapada UV-1800pc
spectrophotometer. C, H, and N elemental analyses were performed
on a Perkin-Elmer 240C elemental analyzer. SEM images were
recorded on a Japan Hitachi model X-650 Scanning electron
microscope. The samples for SEM observation were prepared by
a freeze-drying method. The optical microscopy (OM) images
were obtained on a XP-213 polarizing microscope. The samples
for OM observation were prepared by a method of drop-cast film.
The samples were then kept overnight in a vacuum oven at room
+
C H N : 247.1; found: 248.1 [M + H] .
1
6
13 3
N-Dodecanoyl (L)-phenylalanine (C12Ph). The solution con-
taining L-phenylalanine (2.26 g, 13.7 mmol) and NaOH (0.55 g,
2
13.8 mmol), H O (90 mL) and acetone (30 mL) was cooled for
30 min in an ice-water bath. The acetone solution of dodecanoyl
chloride (3.0 g, 13.8 mmol) and the aqueous solution of NaOH
0.55 g, 13.8 mmol) were slowly and simultaneously added into
(
the above solution. The mixture was stirred overnight and
acidified to pH = 1 using concentrated HCl. The white solid
was obtained by filtration and purified by recrystallization in
petroleum ether. Yield: 83%. mp = 97–98 1C FT-IR: 3313, 3030,
1
temperature. H NMR spectra were recorded on a Bruker Avance
3
1
068, 2950, 2923, 2854, 2479, 1945, 1891, 1701, 1670, 1604, 1246,
118, 697 and 538 cm : elemental analysis (%): calculated for
III 500 MHz NMR spectrometer. Circular dichroism (CD) spectra
of gels were recorded by using a quartz cuvette of 1 mm path
length and using a Biologic PMS 450 spectropolarimeter. Mass
spectra were obtained using Agilent 1100 MS series and AXIMA
CFR MALDI-TOF (Compact) mass spectrometers. Rheological
measurements were carried out on gels using a TA Instruments
AR 2000 and using parallel plates (25 mm diameter).
ꢀ1
C
21
H
33NO
3
: C, 72.58; H, 9.57; N, 4.03; found: C, 72.54; H, 9.54;
) d 8.79 (s, 1H), 7.31–7.15
1
N, 4.04. H NMR (500 MHz, CDCl
3
(m, 5H), 5.92 (d, J = 7.3 Hz, 1H), 4.87 (dd, J = 13.0, 6.3 Hz, 1H),
3
2
0
3
.24 (dd, J = 14.1, 5.5 Hz, 1H), 3.13 (dd, J = 14.1, 6.4 Hz, 1H),
.25–2.03 (m, 2H), 1.56 (d, J = 6.6 Hz, 2H), 1.40–1.08 (m, 16H),
.88 (t, J = 6.9 Hz, 3H). MALDI-TOF MS: m/z: calcd for C21
H
33NO
3
:
+
47.2; found: 346.2 [M ꢀ H] .
Gelation test
N-Octadecanoyl (L)-phenylalanine (C18Ph). Yield: 80%. mp =
4–65 1C FT-IR: 3317, 3032, 3068, 2950, 2923, 2854, 2478, 1702,
The solution containing weighed compound in organic solvent
was heated in a sealed sample bottle with 1 cm diameter in an oil
bath until the solid was dissolved. After the solution was allowed
to stand at room temperature for 6 h, the state of the mixture was
evaluated by the ‘‘stable to inversion of a test tube’’ method.
6
1
ꢀ1
671, 1604, 1246, 1117, 697 and 538 cm : elemental analysis
(
%): calculated for C H NO : C, 75.13; H, 10.51; N, 3.24; found:
27 45 3
1
C, 75.11; H, 10.54; N, 3.25. H NMR (500 MHz, CDCl ) d 8.80
3
(
b, 1H) 7.40–7.07 (m, 5H), 6.02 (s, 1H), 4.85 (s, 1H), 3.24 (dd,
J = 13.8, 4.6 Hz, 1H), 3.11 (dd, J = 13.5, 5.9 Hz, 1H), 2.15 (s, 2H),
.53 (s, 2H), 1.30–1.19 (m, 28H), 0.88 (t, J = 6.8 Hz, 3H).. MALDI-
Gel-to-sol transition temperature (Tgel
)
1
+
The gel-to-sol transition temperature (Tgel) was determined in an TOF MS: m/z: calcd for C H NO : 431.3; found: 431.2 M .
2
7
45
3
oil bath by slowly raising the temperature of the bath at a rate
ꢀ
1
of 1 1C min . The Tgel was defined as the temperature (ꢁ0.5 1C)
at which the gel melted and started to flow.
Acknowledgements
This work was financially supported by the National Natural
Science Foundation of China (21103067), the Youth Science
Foundation of Jilin Province (20130522134JH), the Open Project of
State Laboratory of Theoretical and Computational Chemistry
Synthetic procedures and characterization
C12Ph and C18Ph were synthesized by the reported method
2
4
(
Scheme 1).
E)-4-(Phenyldiazenyl)naphthalen-1-amine (PDNA). Aniline
3.39 g) was added into the mixture of concentrated HCl (7 mL)
(
(K2013-02), and the Fundamental Research Funds for the Central
(
Universities.
and water (10 mL). After the solid was dissolved the aqueous
solution of NaNO (2.5 g) was dropped into the above solution at
2
0
–5 1C. After 2 h, the reaction mixture was neutralized to pH = 6
Notes and references
using potassium acetate. At 0–5 1C the above mixture was added
slowly into the solution containing naphthalen-1-amine (5.2 g),
water (100 mL), ethanol (12 mL) and dense HCl (3 mL). After 10 h,
the solution was neutralized by potassium acetate aqueous
solution (pH = 8–9). The crude product was obtained by filtration
1 (a) T. Aida, E. W. Meijer and S. I. Stupp, Science, 2012, 335,
813–817; (b) T. F. A. De Greef, M. M. J. Smulders, M. Wolffs,
A. P. H. J. Schenning, R. P. Sijbesma and E. W. Meijer, Chem.
Rev., 2009, 109, 5687–5754; (c) F. J. M. Hoeben, P. Jonkheijm,
E. W. Meijer and A. P. H. J. Schenning, Chem. Rev., 2005, 105,
1491–1546; (d) M. Wang, A. R. Mohebbi, Y. Sun and F. Wudl,
Angew. Chem., Int. Ed., 2012, 51, 6920–6924; (e) B. K. An,
J. Gierschner and S. Y. Park, Acc. Chem. Res., 2012, 45,
544–554; ( f ) A. Ajayaghosh and V. K. Praveen, Acc. Chem.
Res., 2007, 40, 644–656; (g) H. Jintoku, T. Sagawa, M. Takafuji
and H. Ihara, Chem. – Eur. J., 2011, 17, 11628–11636.
and purified by a silica gel column using CH
2 2
Cl as the eluent
(R = 0.63). Yield = 91%. mp = 127–128 1C. FT-IR: 3454, 3374, 3324,
f
ꢀ
1
3216, 3052, 3055, 1634, 1617, 1571, 1517, 1465, 749 and 682 cm
.
Elemental analysis (%): calculated for C H N : C, 77.71; H, 5.30;
1
6 13 3
1
N, 16.99; found: C, 77.73; H, 5.33; N, 16.92. H NMR (500 MHz,
CDCl ) d 9.07 (d, J = 8.5 Hz, 1H), 7.99 (dd, J = 8.4, 1.1 Hz, 2H),
.93 (d, J = 8.3 Hz, 1H), 7.82 (d, J = 8.5 Hz, 1H), 7.65 (ddd, J = 8.3,
3
7
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
2
(a) P. Terech and R. G. Weiss, Chem. Rev., 1997, 97,
133–3159; (b) N. Yan, Z. Xu, K. K. Diehn, S. R. Raghavan,
Y. Fang and R. G. Weiss, J. Am. Chem. Soc., 2013, 135, 8989–8999;
c) S. S. Babu, S. Prasanthkumar and A. Ajayaghosh, Angew.
Chem., Int. Ed., 2012, 51, 1766–1776; (d) Z. Zhao, J. W. Y. Lam
and B. Z. Tang, Soft Matter, 2013, 9, 4564–4579; (e) S. K. Samanta
and S. Bhattacharya, Chem. Commun., 2013, 49, 1425–1427;
8 (a) A. R. Hirst, J. F. Miravet, B. Escuder, L. Noirez,
V. Castelletto, I. W. Hamley and D. K. Smith, Chem. – Eur. J.,
2009, 15, 372–379; (b) A. R. Hirst, D. K. Smith, M. C. Feiters
and H. P. M. Geurts, Langmuir, 2004, 20, 7070–7077;
(c) D. Cornwell, B. O. Okesola and D. K. Smith, Soft Matter,
2013, 9, 8730–8736; (d) W. Edwards and D. K. Smith, J. Am.
Chem. Soc., 2013, 135, 5911–5920; (e) A. R. Hirst, D. K. Smith
and J. P. Harrington, Chem. – Eur. J., 2005, 11, 6552–6559.
9 (a) A. Dawn, T. Shiraki, H. Ichikawa, A. Takada, Y. Takahashi,
Y. Tsuchiya, L. T. N. Lien and S. Shinkai, J. Am. Chem. Soc.,
2012, 134, 2161–2171; (b) M. Shirakawa, N. Fujita and
S. Shinkai, J. Am. Chem. Soc., 2003, 125, 9902–9903.
3
(
(
f ) S. S. Babu, K. K. Kartha and A. Ajayaghosh, J. Phys. Chem.
Lett., 2010, 1, 3413–3424; (g) Y. He, Z. Bian, C. Kang, R. Jin and
L. Gao, New J. Chem., 2009, 33, 2073–2080.
(a) I. D. Tevis, W. Tsai, L. C. Palmer, T. Aytun and S. I. Stupp,
ACS Nano, 2012, 6, 2023–2024; (b) Z. Yu, D. Qin, Y. Zhang,
3
4
H. Sun, Y. Luo, Q. Meng and D. Li, Energy Environ. Sci., 2011, 10 (a) X. Yu, X. Cao, L. Chen, H. Lan, B. Liu and T. Yi, Soft
4
, 1298–1305; (c) S. Park, I. Y. Song, J. Lim, Y. S. Kwon,
J. Choi, S. Song, J. Lee and T. Park, Energy Environ. Sci., 2013,
, 1559–1564.
Matter, 2012, 8, 3329–3334; (b) X. Yu, L. Chen, M. Zhang and
T. Yi, Chem. Soc. Rev., 2014, 43, 5346–5371; (c) C. Vijayakumar,
V. K. Praveen and A. Ajayaghosh, Adv. Mater., 2009, 21,
2059–2063; (d) C. Vijayakumar, V. K. Praveen, K. K. Kartha and
A. Ajayaghosh, Phys. Chem. Chem. Phys., 2011, 13, 4942–4949;
(e) R. Abbel, R. van der Weegen, W. Pisula, M. Surin, P. Lecl `e re,
R. Lazzaroni, E. W. Meijer and A. P. H. J. Schenning, Chem. –
Eur. J., 2009, 15, 9737–9746; ( f ) S. Sun, X. Chen, J. Liu, J. Yan and
Y. Fang, Polym. Eng. Sci., 2009, 49, 99–103; (g) Q. Xia, Y. Mao,
J. Wu, T. Shua and T. Yi, J. Mater. Chem. C, 2014, 2, 1854–1861;
(h) Y. Ohsedo, M. Oono, A. Tanaka and H. Watanabe, New
J. Chem., 2013, 37, 2250–2253.
6
(a) J. P. Hong, M. C. Um, S. R. Nam, J. I. Hong and S. Lee,
Chem. Commun., 2009, 310–312; (b) W. W. Tsai, I. D. Tevis,
A. S. Tayi, H. Cui and S. I. Stupp, J. Phys. Chem. B, 2010, 114,
1
4778–14786; (c) D. A. Stone, A. S. Tayi, J. E. Goldberger,
L. C. Palmera and S. I. Stupp, Chem. Commun., 2011, 47,
702–5704; (d) S. Diring, F. Camerel, B. Donnio, T. Dintzer,
5
S. Toffanin, R. Capelli, M. Muccini and R. Ziessel, J. Am.
Chem. Soc., 2009, 131, 18177–18185; (e) R. Marty, R. Nigon,
D. Leite and H. Frauenrath, J. Am. Chem. Soc., 2014, 136,
3
919–3927.
11 (a) X. Yang, R. Lu, P. Xue, B. Li, D. Xu, T. Xu and Y. Zhao,
Langmuir, 2008, 24, 13730–13735; (b) P. Xue, Q. Xu, P. Gong,
C. Qian, A. Ren, Y. Zhang and R. Lu, Chem. Commun., 2013,
49, 5838–5840; (c) P. Xue, R. Lu, P. Zhang, J. Jia, Q. Xu,
T. Zhang, M. Takafuji and H. Ihara, Langmuir, 2013, 29,
417–425; (d) O. Simalou, X. Zhao, R. Lu, P. Xue, X. Yang and
X. Zhang, Langmuir, 2009, 25, 11255–11260; (e) P. Xue,
Q. Xu, P. Gong, C. Qian, Z. Zhang, J. Jia, X. Zhao, R. Lu,
A. Ren and T. Zhang, RSC Adv., 2013, 3, 26403–26411;
( f ) P. Xue, R. Lu, L. Zhao, D. Xu, X. Zhang, K. Li, Z. Song,
X. Yang, M. Takafuji and H. Ihara, Langmuir, 2010, 26,
6669–6675.
5
6
(a) X. Liu, X. Zhang, R. Lu, P. Xue, D. Xu and H. Zhou,
J. Mater. Chem., 2011, 21, 8756–8765; (b) H. Peng, L. Ding,
T. Liu, X. Chen, L. Li, S. Yin and Y. Fang, Chem. – Asian J.,
2
012, 7, 1576–1782; (c) P. Xue, R. Lu, J. Jia, M. Takafuji and
H. Ihara, Chem. – Eur. J., 2012, 18, 3549–3558; (d) Q. Xia,
Y. Mao, J. Wu, T. Shu and T. Yi, J. Mater. Chem. C, 2014, 2,
1
(a) J. W. Chung, S. Yoon, S. Lim, B. An and S. Y. Park, Angew.
Chem., Int. Ed., 2009, 48, 7030–7034; (b) X. Cai, Y. Wu,
L. Wang, N. Yan, J. Liu, X. Fang and Y. Fang, Soft Matter,
854–1861.
2
013, 9, 5807–5814; (c) P. Fat ´a s, J. Bachl, S. Oehm,
A. I. Jim ´ı nez, C. Cativiela and D. D. D ´ı az, Chem. – Eur. J., 12 (a) S. S. Babu, V. K. Praveen and A. Ajayaghosh, Chem. Rev.,
2
013, 19, 8861–8874; (d) Y. Hisamatsu, S. Banerjee,
2014, 114, 1973–2129; (b) A. Hemamalinia and T. M. Das,
New J. Chem., 2013, 37, 2419–2425; (c) X. Yang, G. Zhang,
D. Zhang and D. Zhu, Langmuir, 2010, 26, 11720–11725;
(d) C. Mondal, M. Ganguly, J. Pal, R. Sahoo, A. K. Sinha and
T. Pal, Chem. Commun., 2013, 49, 9428–9430.
M. B. Avinash, T. Govindaraju and C. Schmuck, Angew.
Chem., Int. Ed., 2013, 52, 12550–12554; (e) C. Huang,
L. Chen, J. Huang and L. Xu, RSC Adv., 2014, 4,
1
9538–19549; ( f ) B. Bai, J. Ma, J. Wei, J. Song, H. Wang
and M. Li, Org. Biomol. Chem., 2014, 12, 3478–3483; 13 (a) P. Xue, R. Lu, G. Chen, Y. Zhang, H. Nomoto, M. Takafuji
(
g) S. Sarkar, S. Dutta, S. Chakrabarti, P. Bairi and T. Pal,
and H. Ihara, Chem. – Eur. J., 2007, 13, 8231–8239;
(b) P. Xue, R. Lu, X. Yang, L. Zhao, D. Xu, Y. Liu,
H. Zhang, H. Nomoto, M. Takafuji and H. Ihara, Chem. –
Eur. J., 2009, 15, 9824–9835; (c) S. Yoon, J. H. Kim,
J. W. Chung and S. Y. Park, J. Mater. Chem., 2011, 21,
18971–18973; (d) B. An, D. Lee, J. Lee, Y. Park, H. Song
and S. Y. Park, J. Am. Chem. Soc., 2004, 126, 10232–10233;
(e) X. Li, X. Zhang, S. Ghosh and F. W u¨ rthner, Chem. – Eur. J.,
2008, 14, 8074–8078.
ACS Appl. Mater. Interfaces, 2014, 6, 6308–6316; (h) Y. Tian,
L. Zhang, P. Duan, F. Liu, B. Zhang, C. Liu and M. Liu, New
J. Chem., 2010, 34, 2847–2852.
(a) Y. Liu, T. Wang and M. Liu, Chem. – Eur. J., 2012, 18,
1
Rev., 2012, 41, 6089–6102; (c) A. R. Hirst and D. K. Smith,
Chem. – Eur. J., 2005, 11, 5496–5508; (d) M. Suzuki, H. Saito,
H. Shirai and K. Hanabusa, New J. Chem., 2007, 31, 1654–1660;
7
4650–14659; (b) L. E. Buerklea and S. J. Rowan, Chem. Soc.
(e) R. Amemiya, M. Mizutani and M. Yamaguchi, Angew. 14 (a) C. Bao, R. Lu, M. Jin, P. Xue, C. Tan, G. Liu and Y. Zhao,
Chem., Int. Ed., 2010, 49, 1995–1999; ( f ) N. Wu, J. Zhang,
X. Xu and H. Yang, Chem. Commun., 2014, 50, 10269–10272.
Org. Biomol. Chem., 2005, 3, 2508–2512; (b) O. Simalou,
P. Xue and R. Lu, Tetrahedron Lett., 2010, 51, 3685–3690.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
1
5 (a) C. Tan, Y. Zhu, R. Lu, P. Xue, C. Bao, X. Liu, Z. Fei and
Y. Zhao, Mater. Chem. Phys., 2005, 91, 44–47; (b) V. Doan,
R. K o¨ ppe and P. H. Kasai, J. Am. Chem. Soc., 1997, 119,
and S. J. George, Angew. Chem., Int. Ed., 2006, 45, 456–460;
(c) K. Murata, M. Aoki, T. Suzuki, T. Harada, H. Kawabata,
T. Komri, F. Ohseto, K. Ueda and S. Shinkai, J. Am. Chem.
Soc., 1994, 116, 6664–6676; (d) V. V. Borovkov and Y. Inoue,
Top. Curr. Chem., 2006, 265, 89–146; (e) T. Arimura,
S. Edamitsu, S. Shinkai, O. Manabe, T. Muramatsu and
M. Tashiro, Chem. Lett., 1987, 2269–2272.
9810–9815.
1
1
6 Y. Q. Tian, X. H. Xu, Y. Y. Zhao, X. Y. Tang and T. J. Li, Liq.
Cryst., 1997, 22, 87–96.
7 (a) X. Zhu, Y. Li, P. Duan and M. Liu, Chem. – Eur. J., 2010,
16, 8034–8040; (b) P. Xue, R. Lu, J. Jia, M. Takafuji and 21 (a) P. Xue, Y. Zhang, J. Jia, D. Xu, X. Zhang, X. Liu, H. Zhou,
H. Ihara, Chem. – Eur. J., 2012, 18, 3549; (c) J. Puigmart-Luis,
P. Zhang, R. Lu, M. Takafuji and H. Ihara, Soft Matter, 2011, 7,
8296–8304; (b) H. Jintoku, M. Takafuji, R. Oda and H. Ihara,
Chem. Commun., 2012, 48, 4881–4883; (c) S. Allenmark,
Chirality, 2003, 15, 409–422; (d) T. Ishi-i, J. H. Jung and
S. Shinkai, J. Mater. Chem., 2000, 10, 2238–2240; (e) G. Qing,
X. Shan, W. Chen, Z. Lv, P. Xiong and T. Sun, Angew. Chem.,
Int. Ed., 2014, 53, 2124–2129.
´
V. Laukhin, A. P. del Pino, J. Vidal-Gancedo, C. Rovira,
E. Laukhina and D. B. Amabilino, Angew. Chem., Int. Ed.,
2
007, 46, 238–241; (d) F. Aparicio, B. Nieto-Ortega, F. N ´a jera,
F. J. Ram ´ı ez, J. T. L. Navarrete, J. Casado and L. S ´a nchez, Angew.
Chem., Int. Ed., 2014, 53, 1373–1377; (e) T. K. S. Mukherjee and
P. K. Das, New J. Chem., 2014, 38, 1158–1167; ( f ) M. Suzuki,
T. Nigawara, M. Yumoto, M. Kimura, H. Shirai and K. Hanabusa, 22 (a) P. Mukhopadhyay, N. Fujita, A. Takada, T. Kishida,
Org. Biomol. Chem., 2003, 1, 4124–4131.
8 (a) B. G. Bag, G. C. Maity and S. K. Dinda, Org. Lett., 2006, 8,
M. Shirakawa and S. Shinkai, Angew. Chem., Int. Ed., 2010,
49, 6338–6342; (b) X. Yu, X. Cao, L. Chen, H. Lan, B. Liu and
T. Yi, Soft Matter, 2012, 8, 3329–3334; (c) M. Lescanne,
P. Grondin, A. d’Al ´e o, F. Fages, J. L. Pozzo, O. M. Monval,
P. Reinheimer and A. Colin, Langmuir, 2004, 20, 3032–3041.
1
5
457–5460; (b) U. Maitra, P. V. Kumar, N. Chandra,
L. J. D’Souza, M. D. Prasanna and A. R. Raju, Chem. Commun.,
999, 595–596; (c) J. Hu, J. Wu, Q. Wang and Y. Ju, Beilstein
1
J. Org. Chem., 2013, 9, 2877–2885; (d) A. Friggeri, 23 (a) V. Percec, M. Peterca, M. E. Yurchenko, J. G. Rudick and
O. Gronwald, K. J. C. van Bommel, S. Shinkai and
D. N. Reinhoud, J. Am. Chem. Soc., 2002, 124, 10754–10758.
9 (a) W. Edwards and D. K. Smith, J. Am. Chem. Soc., 2014,
P. A. Heiney, Chem. – Eur. J., 2008, 14, 909–918; (b) J. Brinksma,
B. L. Feringa, R. M. Kellogg, R. Vreeker and J. van Esch,
Langmuir, 2000, 16, 9249–9255; (c) Y. Feng, Z. Liu, H. Chen,
Z. Yan, Y. He, C. Liu and Q. Fan, Chem. – Eur. J., 2014, 20,
7069–7082.
1
136, 1116–1124; (b) M. J. Hynes, J. Chem. Soc., Dalton Trans.,
1993, 311–312; (c) P. N. Borer, B. Dengler, I. J. Tinoco and
O. C. Uhlenbeck, J. Mol. Biol., 1974, 86, 843–853.
0 (a) C. Thalacker and F. W u¨ rthner, Adv. Funct. Mater., 2002,
24 (a) S. Y. Mhaskar, R. B. N. Prasad and G. Lakshminarayana,
J. Am. Oil Chem. Soc., 1990, 67, 1015–1019; (b) A. Pal, Y. K. Ghosh
and S. Bhattacharya, Tetrahedron, 2007, 63, 7334–7348.
2
12, 209–218; (b) A. Ajayaghosh, C. Vijayakumar, R. Varghese
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.