Unimolecular Photopolymerization of High-Emissive Materials on Cylindrical Self-Assemblies

Article abstract of DOI:10.1021/acs.macromol.5b01488

We report a novel self-assembly pathway from a bis(imidazolyl) diphenyl-diacetylene (DPDA) compound as a realization of self-templated photopolymerization with high polymerization degrees. The work takes advantage of a cylindrical self-assembly that stren

Full text of DOI:10.1021/acs.macromol.5b01488

Article
pubs.acs.org/Macromolecules
Unimolecular Photopolymerization of High-Emissive Materials on
Cylindrical Self-Assemblies
Liangliang Zhu,*,†,§ Xin Li,‡ Samuel N. Sanders,§ and Hans Ågren*,‡
†State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai
200433, China
‡Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm,
Sweden
§Department of Chemistry, Columbia University, New York, New York 10027, United States
S
* Supporting Information
ABSTRACT: We report a novel self-assembly pathway from a
bis(imidazolyl) diphenyl−diacetylene (DPDA) compound as a
realization of self-templated photopolymerization with high
polymerization degrees. The work takes advantage of a cylindrical
self-assembly that strengthens the preorganization of the
diphenyl−diacetylene moiety at the single molecular level. On
this basis, photopolymerization of DPDA can be conducted
smoothly to form high-molecular-weight polydiphenyl diacetylene.
Such a cylindrical self-assembly is highly dependent on molecular
structure, and control studies show that only oligomers can be
formed on random self-assemblies from a monoimidazolyl or
nonimidazolyl diphenyl−diacetylene compound. Moreover, the
cylindrical self-assembly based systems bear aggregation-induced
emission enhancement characteristics and are solution processable.
The leading thin-film could afford a selectively tunable function in luminescent micropatterns.
Gelation and monolayer strategies may somehow promote the
polymerization of DPDAs,8 but they lack solution process-
ability, which will limit large-scale development. A straightfor-
ward approach for enhancing the polymerization degree of
DPDA in a solution processable manner remains a challenge.
Structural-dependent ordered self-assembled nanoarchitec-
tures formed in a certain solvent environment generally show
properties distinct from those of their individual constituent
molecules,9and can even be helpful for improving the chemical
reaction behavior.10 In particular, self-assemblies formed by a
surfactant-like design could readily generate distinctive super-
structures in aqueous media thus to provide widely tunable
performance and effective solution-based processing character-
istics.11Inspired by the superiority of these pertinent super-
structures,9−11 we herein present a unimolecular strategy (see
compound 1 in Figure 1) of introducing a diphenyl−
diacetylene (DPDA) moiety as a polymerizable core and two
imidazole units as bilateral headgroups to realize this
supposition. This design takes advantage of the facts that (1)
the amphiphilic molecular structure can be employed to
establish ordered self-assemblies in aqueous media for
improving the polymerization behavior; (2) DPDA was bridged
INTRODUCTION
■
As compared with most conventional diacetylenes with alkyl
chains directly connected to the butadiyne unit, the diphenyl−
diacetylene (DPDA) moiety with aryl groups attached to the
butadiyne has an extended π-conjunction and introduces a large
intermolecular stacking tendency. These features generally
allow the mesogen as well as the corresponding polydiacetylene
species to exhibit more versatile optoelectronic properties,1−3
implying great interest for their potential exploitation in high
birefringence materials, modern display technologies, lumines-
cent emitting diodes, and ideal prototype for molecular devices,
etc.4 Since the first report of diacetylene polymerization in the
solid state by Wegner,5 it has been widely accepted that
molecular preorganization is a crucial factor to achieve highly
efficient topochemical polymerizations of diacetylene. To drive
such an effective polymerization on a diphenyl−diacetylene
(DPDA) monomer seems to be difficult, simply because the
bulky size of the neighboring phenyl rings in DPDA greatly
hampers the minimum movement of the butadiyne moiety. The
past decades have witnessed extensive progress in developing
many key strategies, based on grafting diacetylene monomers
on surface-aligned films or introducing functional groups on the
diacetylene monomers to control their aggregation and
crystallization, followed by thermal or photochemical polymer-
ization.6 However, only the formation of oligomers, or even no
reaction at all, is observed in most of cases of DPDAs.7
Received: July 7, 2015
Revised: July 20, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
RESULTS AND DISCUSSION
■
Cylindrical Self-Assembly of 1. To study the self-
assembly behavior of compounds 1−3, we first investigated
their photophysics. A colloidal solution of compound 1 was
observed in a mixed solvent system. 1 exists as monomeric state
in an anhydrous THF solution and its absorption bands can be
well assigned. The multiple peaks from 270 to 345 nm (curve 1,
Figure S1) originate from the alkynyl and aromatic
chromophores in 1. However, the absorption bands of 1
dispersed in THF with 90% water turns broad and all the main
peaks accordingly exhibit a bathochromical shift for ca. 10 nm
(curve 2, Figure S1), signifying that 1 forms a self-aggregated
state in the presence of a large amount of water. The self-
aggregation properties of 1 were examined by monitoring the
variation of absorption upon the concentration change. The
critical aggregation concentration (CAC) in THF with 90%
water was determined to be 15.5 μM (Figure S2, Supporting
Information).
To our surprise, the photoluminescent spectral change of 1
follows an opposite trend toward the UV−vis change upon
increasing the content of water. As seen from Figure 2A, 1
shows an emission maximum at around 410 nm while no
remarkable emission enhancement is observed from THF
solution with water content less than 70%. However, when a
large amount of water (fw >80%) is admixed with THF, the
emission intensity grows significantlyapproximately an 8-fold
increase over the intensity in neat THF solution. Such a distinct
photoluminescence can also be directly observed by the naked
eye (see the photographs in Figure S3). In contrast, the
emission intensity of the reference compound 2 and 3
decreases continuously in THF with increasing content of
water (see Figure 2, parts B and C). Attempts to obtain the
quantum yield of the aggregated state were unsuccessful,
Figure 1. (A) Chemical structures of the compound 1 and the
reference compounds 2 and 3. (B) Schematic representation of the
unimolecular photopolymerization process in aqueous media. By UV
irradiation under this solvent condition, 1 can form the corresponding
polymer species whereas 2 and 3 only produce oligomers.
with imidazole headgroups via two long alkyl chains, which are
also considered to regulate the self-assembly modes and
increase the processability from solution to solid state; (3)
DPDA is a smart luminogen whose photophysics can be
employed and modulated upon self-assembly and photo-
polymerization for high-tech applications with emissive
expressions. Reference compounds 2 and 3 with mono- or
nonimidazole headgroups, respectively, were also prepared for
control experiments. The synthesis of these compounds is
detailed in the Experimental Section.
Figure 2. (A−-C) Emission spectra (λex = 365 nm) of 1, 2, and 3, respectively, 40 μM, 298 K, in anhydrous THF (curve 1), THF with 30% water
(curve 2), THF with 70% water (curve 3), THF with 80% water (curve 4), and THF with 90% water (curve 5). (D−F) AFM images of 1, 2 and 3,
respectively, prepared from THF with 90% water. Scale bar: 1 μm.
B
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Figure 3. (A) Representative cylindrical self-assembly conformation of 1 from molecular dynamics simulations. (B) Distribution of van der Waals
interaction energies among the DPDA groups (curve 1−3) in the self-assemblies of compound 1, 2, and 3, respectively. (C) Autocorrelation
functions of the dihedral angle between the two phenyl rings (curve 1−3) in the self-assemblies of compounds 1, 2, and 3, respectively. Dashed lines
show fitting to the Kohlrausch−Williams−Watts relaxation function, from which the correlation time is calculated.
probably due to scattering; however, the huge differences
among the intensities in these experimental results suggest that
compound 1 is aggregation-induced emission enhancement
(AIEE) active12 and that this effect is structurally dependent,
opposite to the ordinary aggregation-caused quenching (ACQ)
effect of 2 and 3.13
Supporting Information), which is indicative of the formation
of an advanced column-shaped architecture through further
extension of the supramolecular interactions (Figure 2D).
Notably, the self-aggregation pattern was largely regulated by
the bilateral imidazole units, which show some hydrophilic
properties and stretch toward the water medium. Thus, the
diacetylene moiety was enforced to stay at the middle of the
cylinders, resulting in a self-sorted aggregation mode as shown
in Figure 3A.
The self-aggregated architectures under the specific solvent
conditions were further confirmed by atomic force microscopic
(AFM) studies. Column-shaped nanostructures with an average
cross-sectional diameter of 500 nm were observed from the
AFM images of 1 prepared from a THF/H2O (v:v = 1:9)
mixture solution (Figure 2D and Figure S7a in the Supporting
Information), whereas common spherical aggregates were
obtained from the reference compound 2 and 3 when prepared
in the same solvent conditions (Figure 2, parts E and F). It can
be suggested that such a peculiar self-assembly of 1 is
responsible for the generation of the AIEE effect. The XRD
diffractogram of the self-aggregated sample 1 shows a main
peak with a d-spacing of 3.54 Å (corresponding to the peak at
2θ = 25.1°, see curve 1 in Figure S4), which originates from the
stacking of the aromatic chromophore.14 This d-spacing value
was enlarged in samples of 2 and 3 up to 3.77 and 3.60 Å,
respectively, indicating different packing modes and weaker
π−π interactions in these crystalline samples (see also the
computational works for comparison, vide infra).
To gain further insight into the fine superstructures of the
nanoassemblies, molecular dynamics (MD) simulations15 were
carried out to study the self-assembly behavior of compound 1.
It was found that all molecules of 1 start to form aggregates in
the presence of an aqueous environment, and that the self-
assembly of 1 exhibits a distinct cylindrical conformation
(Figure 3A). The computed solvent accessible surface area and
order parameter suggest an ordered self-assembly of 1 (see
The aggregation characteristics of the three compounds were
also compared by MD simulations. We examined the van der
Waals (VDW) interaction potential energies among the DPDA
groups in the self-assemblies, which reflect the strengths of π−π
interactions. Figure 3B shows the distributions of the VDW
interaction energies in the self-assembled compounds. Here,
the positions of the peaks indicate that the strength of the
VDW interaction among the DPDA groups follows the order 1
> 3 ≫ 2, in accordance with the molecular packing distance
provided by XRD spectra (Figure S4). The rotation of the
phenyl−phenyl dihedral in the DPDA moiety before and after
self-aggregation was also examined. It can be seen that the
autocorrelation function of compound 1 decays much slower
than those of compounds 2 and 3, suggesting that the rotation
of the two phenyl rings are restricted in the self-assembled
molecules of 1 (Figure 3C). In this way, it can be concluded
that a barrier was established after the formation of the
cylindrical self-assembly of 1. Since the rotation of the aromatic
rings is considered as a crucial factor for photoluminescent
quenching, this finding is indeed in agreement with the
restriction of intramolecular rotation (RIR) mechanism.16
Therefore, such a confined nanoconformation significantly
enhances the quantum yield and in turn leads to the AIEE
effect.
C
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
High Polymerization Degree of 1 on Cylindrical Self-
Assembly. On the basis of these self-assemblies, next we turn
to study their polymerization degree by gel permeation
chromatography (GPC). The photopolymerization of these
compounds does not proceed with high efficiency in neat THF
solution, however, it could be promoted in the colloidal media
of THF with 90% water. Figure 4 shows the GPC
injection. On the basis of a polystyrene calibration curve, we
can see that compound 2 and 3 only form corresponding
oligomers upon photoirradiation (Figure 4, parts C and E). In
contrast, compound 1 results in a great deal of polymers except
some oligomers upon photoirradiation, as confirmed by an
extended broad band in Figure 4A. The degree of polymer-
ization (number of repeating units in the polymeric chain) was
observed to exceed 40 in the highest molecular weight species.
Since the sample solubility was proven to matter little about the
chain length, it is concluded here that such a unique self-
assembly of 1 leads to a higher degree of topochemical
polymerization.
Learning from the specific self-sorting of the DPDA moiety
and the bilateral imidazole units presented in the model in
Figure 3A as well as the RIR mode of the luminogen, we
suggest a locally ordered DPDA alignment was achieved inside
the cylinderical nanostructures. This specific packing of the
luminogen of this amphiphilic molecule keeps a quite favorable
preorganization of the DA moiety, such that a facile
polymerization can be conducted to yield high-molecular-
weight polymer species. In contrast, the random self-assemblies
of 2 and 3 exhibit very limited preorganization of the DPDA
moiety, offering oligomers only. Moreover, the UV−vis band
changes upon photoirradiation provide additional evidence for
the polymerization degree. To diminish the interference of the
scattering from a colloidal solution, we isolated and redissolved
the irradiated stuffs for UV−vis measurements. A continuous
absorption from UV region to over 580 nm of 1 after
irradiation was observed, indicating the formation of polymer
species, whereas the absorption band (corresponding to
oligomers) of 2 and 3 did not reach 500 nm after irradiation
(Figure S5).
Figure 4. GPC traces of the diacetylene samples with or without UV
irradiation.(254 nm Detector, THF eluent): (A, C, E) Compounds 1,
2, and 3 after irradiation, respectively. (B, D, F) Compounds 1, 2, and
3 without irradiation, respectively. Some representative polymerization
degrees were highlighted next to the traces.
Accompanied by such a photopolymerization process, an
obvious luminescent conversion can be observed upon UV
irradiation in the colloidal solution of 1. The original emission
band of 1 at around 420 nm was weakened, meanwhile a new
peak at ∼520 nm emerged due to photoluminescence of the
polymer species (Figure S6). Upon photopolymerization, the
AIEE effect of 1 was diminished with the shrinkage of the
cylindrical nanostructures (see the AFM characterization in
chromatograms of these three compounds before and after
photoirradiation. These GPC samples were first prepared from
the above-mentioned mixed solvent condition with or without
photoirradiation, followed by isolation and redissolvation for
Figure 5. Emission spectra (λex = 340 nm) of dumbbell molecule 1 (0.021 mM in DMSO, 295 K) (a) before and (b) after irradiation at 365 nm for
300 s, when compared with significant emission change for [3]rotaxane R1 (0.021 mM in DMSO, 295 K) and (c) before and (d) after irradiation at
365 nm for 300 s.
D
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Figure S7). A possible cycloaromatization mechanism17 could
be ruled out since the PL spectra varied according to first-order
kinetics with prolonged photoirradiation time (see Figure S8).
In this way, we suggest that the polymer species here are most
likely based on an enyne skeleton after a topochemical 1,4-
addition reaction. As shown in the AFM image in Figure S7b, it
can be also concluded that the polydiphenyl diacetylene
backbones are linear under the current preparation condition,
since the rigidity of the enyne skeleton are unfavorable for the
formation of a macrocyclic conformation.18
Solution Processability and Photopatterning. Such a
photoluminescent conversion with high emissive signals of 1
can be processed from solution to thin film by spin coating. In
contrast, the photoluminescent behavior of compound 2 and 3
in the solid-state was completely suppressed. As shown in
Figure 5A, we can observe that the solid-state emissive signal of
1 is still strong (curve 1), and that the emission of 2 and 3 was
quenched in films (curve 2 and 3). A comparison of AFM
images (Figure S9) confirms that cylindrical nanostructures are
still present in the film surface of 1, clarifying that the AIEE
effect still exists in the solid-state sample. Similar to the
behavior in the solution self-assemblies (Figure S6), the
photoluminescent change along with the photopolymerization
process of 1 on thin film can also be observed upon the
prolonging of UV irradiation (see curve 1 and p1 in Figure 5A).
Here we can find that the photoluminescent signal conversion
of 1 before and after polymerization on thin film can still be
clearly distinguished. We emphasize that such a highly emissive
event in the solid state still refers to a unimolecular process
without any assistance of matrix materials or templates.
Furthermore, this strategy with the superiority of strong
emission, photoinduced luminescent conversion, solution
processable characteristic, etc. is amenable to patterning over
large areas and can exhibit an unprecedented potential for
regionally selective emitting upon the channel (excitation/
collection) switching. The photopatterning treatment19can be
visualized by the schematic presentation in Figure 5B. A quartz
mask with a microscale grid was placed on the film of 1 for a
region-selective photoirradiation. Micropatterned imaging
based on thin film 1 can be obtained after UV irradiation as
monitored by confocal microscopy. To our delight, a
phenomenon of regionally selective imaging could be created
by switching of different detection modes. The bright imaging
of square areas can be clearly observed from a FITC mode
(excitation/reading wavelengths: ∼ 490/560−580 nm), while
the imaging of the rest lane parts appear dark (Figure 5C). In
contrast, the imaging of the square areas is relatively weak from
a DAPI mode (excitation/reading wavelengths: ∼ 350/440−
460 nm), whereas it is remarkably strengthened within the rest
lane parts (Figure 5D). The luminescent intensity along the
line profile from the FITC mode shows a peak-trough-peak
fluctuation; however, the intensity at the same location from
the DAPI mode behaves in a totally inverted manner (Figure
S10). As we demonstrated above, the photopolymerization
allows the emission of the materials to undergo a significant
bathochromical shift. This exploration suggests that the
photopolymerization took place only in those exposed square
areas since the brightness information performed by the
microspectroscopy is in agreement with the corresponding
photoluminescent spectra. Such a controllable regionally
selective imaging might find a promising potential for
applications of advanced optical imaging or lightening events
at microscale.20
CONCLUSION
■
We have demonstrated a bi-imidazolyl diphenyl diacetylene
(DPDA) compound that can act as a scaffold for a single-
molecule based photopolymerization with high polymerization
degree. Distinctive cylindrical self-assemblies of this molecule
can be formed in a colloidal aqueous solution and can be
processed into thin-film. Such a structural-dependent ordered
nanoarchitecture with the DPDA moiety packed toward the
inside and the bilateral imidazole units in the periphery is
favorable for molecular preorganization of the DPDA moiety.
On this basis, a topochemical reaction that yields high
molecular weight polydiacetylenes was observed upon UV
irradiation. In addition, this molecule exhibited an effect of
aggregation-induced emission enhancement not only in the
colloidal solution but also in the solid state. Regionally selective
imaging control using films of this unique compound has been
successfully carried out at the micropattern level. Future studies
will be geared toward exploiting this self-templated strategy,
which also could be useful for other topochemical reactions that
require highly uniform molecular alignment.
EXPERIMENTAL SECTION
■
General Data. 1H NMR and 13C NMR spectra were measured on
a Bruker 400L spectrometer. The fast atom bombardment (FAB) mass
spectra and high-resolution mass spectrometry (HR-MS) were
recorded on a JMS-HX110 HF mass spectrometer (ionization mode:
FAB+). Absorption spectra were recorded on a Shimadzu 1800
spectrophotometer, while the fluorescent emission spectra were taken
with a Jobin Yvon Fluorolog-3 spectrofluorometer (Model FL-TAU3).
The photoirradiation was carried on PL Series compact UV lamp (4
W) with the irradiation wavelength of 254 nm. The distance between
the lamp and the sample is kept within 3−5 cm. The polymer
molecular weight were determined with a Waters 1515 gel permeation
chromatograph (GPC) equipped with a UV detector and calibrated
with polystyrene standard samples. The Atomic force microscopy
(AFM) images were collected on a PSI XE100 atomic force
microscope (Park System). The confocal microscopic images were
captured by LEICA TCS SP5 confocal microscope. The photo images
were photographed by a Nikon COOLPIX S8000 digital camera.
Synthesis of Compound 6. The preparation for this compound was
according to a similar procedure described in the literature.21
Synthesis of Compound 5. A solution of hexyl bromide (1.05 g,
6.36 mmol) in anhydrous acetone (5 mL) was added dropwise into a
mixture of compound 6 (1.5 g, 6.41 mmol) and potassium carbonate
(0.8 g, 5.8 mmol) in anhydrous acetone (15 mL) at 60 °C. The
mixture was kept stirring for 12 h at that temperature under Ar
protection. The solvent was removed in vacuo, and the residue was
applied to silica gel chromatography (hexane/ethyl acetate =6:1) to
afford gray compound 5 (1.02 g, 50.4%). 1H NMR (400 MHz, CDCl3,
298 K): δ = 7.45 (d, J = 9.2 Hz, 2H), 7.42 (d, J = 8.8 Hz, 2H), 6.84 (d,
J = 8.8 Hz, 2H), 6.79 (d, J = 8.8 Hz, 2H), 3.97 (t, J = 6.4 Hz, 2H), 1.79
(m, 2H), 1.46 (m, 2H), 1.35 (m, 4H), 0.91 (t, J = 7.2 Hz, 3H). 13C
NMR (100 MHz, CDCl3, 298 K): δ = 159.91, 156.32, 134.29, 134.06,
115.66, 114.68, 114.36, 113.62, 81,43, 81.00, 73.01, 72.82, 68.25,
31.57, 29.18, 25.76, 22.60, 14.04. MS (FAB+): calcd for [M]+ m/z =
318.2; found m/z = 318.3; HR-MS (FAB+): calcd for C22H22O2 [M]+
m/z = 318.1620; found m/z = 318.1619.
Synthesis of Compound 4. Compound 5 (0.6 g, 1.89 mmol) was
added with magnetic stirring to 1,6-dibromohexane (4.5 g, 18.4 mmol)
acetone solution (5 mL). The mixture was then added upon potassium
carbonate (520 mg, 3.77 mmol). The mixture was stirred refluxing for
6 h under Ar protection and then was filtered. A great deal of solid was
precipitated from the filtrate while it was added into 4 fold volume of
hexane. The solid was filtered, washed with petroleum (30 mL) and
deionized water (20 mL), respectively, and dried under vacuum to
obtain gray compound 4 (737 mg, 81.1%). 1H NMR (400 MHz,
CDCl3, 298 K): δ = 7.44 (d, J = 8.0 Hz, 4H), 6.83 (d, J = 7.6 Hz, 4H),
E
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Figure 6. Synthetic route for the preparation of compounds 1, 2 and 3. Reagents and conditions: (i) Pd(PPh3)2Cl2, CuI, Et3N, DMF, (ii) Ag2CO3,
heating, (iii) hexyl bromide or dodecyl bromide, K2CO3, (iv) dibromoalkane, K2CO3, and (v) imidazole, KOH.
3.97 (m, 4H), 3.42 (t, J = 6.8 Hz, 2H), 1.90 (m, 2H), 1.81 (m, 4H),
1.50 (m, 6H), 1.34 (m, 4H), 0.91 (t, J = 6.8 Hz, 3H). 13C NMR (100
MHz, CDCl3, 298 K): δ = 159.89, 159.74, 134.04, 134.04, 114.66,
114.64, 113.85, 113.67, 81,38, 81.27, 72.97, 72.89, 68.17, 67.86, 33.79,
32.66, 31.56, 29.13, 28.99, 27.91, 25.69, 25.28, 22.61, 14.03. MS (FAB
+): calcd for [M]+ m/z = 480.2 (79Br); found m/z = 480.2 (79Br); HR-
MS (FAB+): calcd for C28H33O279Br [M]+ m/z = 480.1664; found m/
z = 480.1668.
Synthesis of Compound 3. Compound 6 (234 mg, 1.0 mmol) was
added with magnetic stirring to 1,6-dibromohexane (4.8 g, 19.6 mmol)
acetone solution (4 mL). The mixture was then added upon potassium
carbonate (552 mg, 4.02 mmol). The mixture was stirred refluxing for
6 h under Ar protection and then was filtered. A great deal of solid was
precipitated from the filtrate while it was added into a 5-fold volume of
hexane. The solid was filtered, washed with petroleum ether (20 mL)
and deionized water (15 mL), respectively, and dried under vacuum to
obtain gray compound 3 (449 mg, 80.2%). 1H NMR (400 MHz,
CDCl3, 298 K): δ = 7.44 (d, J = 9.0 Hz, 4H), 6.83 (d, J = 9.0 Hz, 4H),
3.97 (t, J = 6.4 Hz, 4H), 3.42 (t, J = 6.4 Hz, 4H), 1.89 (m, 4H), 1.80
(m, 4H), 1.50 (m, 8H). 13C NMR (100 MHz, CDCl3, 298 K): δ =
159.76, 134.05, 114.64, 113.82, 81.31, 72.95, 67.85, 33.72, 32.66,
28.99, 27.91, 25.28. MS (FAB+): calcd for [M]+ m/z = 558.1 (79Br);
found m/z = 558.2 (79Br); HR-MS (FAB+): calcd for C28H32O279Br2
[M]+ m/z = 558.0769; found m/z = 558.0791. A scheme showing the
syntheses of 1−3 is found in Figure 6.
81,42, 81.21, 73.01, 72.87, 68.16, 67.72, 46.94, 31.56, 31.03, 29.12,
28.97, 26.34, 25.69, 25.62, 22.60, 14.03. MS (FAB+): calcd for [M +
H]+ m/z = 469.3; found m/z = 469.4; HR-MS (FAB+): calcd for
C31H37O2N2 [M + H]+ m/z = 469.2855; found m/z = 469.2860.
Synthesis of Compound 1. To a mixture of compound 3 (200 mg,
0.36 mmol) and potassium hydroxide (80 mg, 1.43 mmol) in
acetonitrile (2.5 mL) was added imidazole (340 mg, 5.0 mmol). The
reaction mixture was refluxed for 8 h and then cooled to room
temperature. After a flash column chromatography (ethyl acetate/
methanol =25:6), the crude product was further washed with
deionized water (25 mL) and dried under vacuum to obtain pure
1
white compound 1 (152 mg, 76.7%). H NMR (400 MHz, CDCl3,
298 K): δ = 7.46 (s, 1H), 7.44 (d, J = 8.4 Hz, 4H), 7.06 (s, 1H), 6.91
(s, 1H), 6.82 (d, J = 8.8 Hz, 4H), 3.95 (t, J = 6.4 Hz, 8H), 1.80 (m,
8H), 1.50 (m, 4H), 1.36 (m, 4H). 13C NMR (100 MHz, CDCl3, 298
K): δ = 159.70, 137.08, 134.05, 129.50, 118.76, 114.62, 113.86, 81.29,
72.97, 67.74, 46.93, 31.03, 28.97, 26.33, 25.62. MS (FAB+): calcd for
[M + H]+ m/z = 535.3; found m/z = 535.4; HR-MS (FAB+): calcd for
C34H39O2N4 [M + H]+ m/z = 535.3073; found m/z = 535.3068.
Preparation of the Colloidal Solutions. THF solutions of 1, 2,
and 3 with concentration of 6 mM (1 mL) were added dropwise into a
water-dominated mixed solvent (150 mL) with stirring. The leading
colloidal solutions were standed for 15 min for the later related
measurements.
Preparation of the Thin Films. The films of 1, 2, and 3 were
obtained by spin-coating (2500 rpm for 45 s) the corresponding THF
solutions with concentration of 6 mM on silicon wafers. The wafers
were inserted into the cuvette holder with an angle about ∼45° to the
incident light for the optical tests.
Synthesis of Compound 2. To a mixture of compound 4 (650 mg,
1.35 mmol) and potassium hydroxide (151 mg, 2.78 mmol) in
acetonitrile (6 mL) was added imidazole (645 mg, 9.48 mmol). The
reaction mixture was refluxed for 8 h and then cooled to room
temperature. After a flash column chromatography (ethyl acetate/
methanol = 25:2), the crude product was further washed with
deionized water (15 mL) and dried under vacuum to obtain pure
Photopatterning. Upon the preparation of the thin film 1, a
quartz mask with microscale grid was placed on the film with nitrogen
purging. Photoirradiation with UV light was sufficient conducted for
20 min. Then, the film was observed under confocal microscopy with
different channels. The intensity of each channel was read under the
same gain.
1
white compound 2 (255 mg, 40.4%). H NMR (400 MHz, CDCl3,
298 K): δ = 7.46 (s, 1H), 7.44 (d, J = 8.4 Hz, 4H), 7.06 (s, 1H), 6.91
(s, 1H), 6.84 (d, J = 8.8 Hz, 2H), 6.81 (d, J = 8.4 Hz, 2H), 3.96 (m,
6H), 1.78 (m, 6H), 1.47 (m, 4H), 1.34 (m, 6H), 0.91 (t, J = 6.8 Hz,
3H). 13C NMR (100 MHz, CDCl3, 298 K): δ = 159.90, 159.67,
137.10, 134.04, 134.04, 129.50, 118.77, 114.67, 114.62, 113.91, 113.65,
F
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
(9) (a) Aida, T.; Meijer, E. W.; Stupp, S. I. Science 2012, 335, 813.
(b) Gopal, A.; Hifsudheen, M.; Furumi, S.; Takeuchi, M.; Ajayaghosh,
A. Angew. Chem., Int. Ed. 2012, 51, 10505. (c) Kiyonaka, S.; Sada, K.;
Yoshimura, I.; Shinkai, S.; Kato, N.; Hamachi, I. Nat. Mater. 2004, 3,
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.macro-
mol.5b01488.
■
S
58. (d) Zhang, X.; Chen, Z.; Wurthner, F. J. Am. Chem. Soc. 2007, 129,
̈
4886. (e) Zhu, L.; Li, X.; Zhang, Q.; Ma, X.; Li, M.; Zhang, H.; Luo,
Z.; Ågren, H.; Zhao, Y. J. Am. Chem. Soc. 2013, 135, 5175. (f) Ji, F.-Y.;
Zhu, L.-L. Chin. J. Org. Chem. 2011, 31, 973.
Supporting experimental data (including UV−vis, PL,
XRD, AFM, etc.) and computational details (PDF)
(10) (a) Eelkema, R.; van Esch, J. H. Org. Biomol. Chem. 2014, 12,
6292. (b) Gazit, E. Nat. Chem. 2010, 2, 1010.
AUTHOR INFORMATION
Corresponding Authors
*(L.Z.) E-mail: zhuliangliang@fudan.edu.cn.
*(H.Å.) E-mail:agren@theochem.kth.se.
Notes
(11) (a) Qiu, H.; Russo, G.; Rupar, P. A.; Chabanne, L.; Winnik, M.
A.; Manners, I. Angew. Chem., Int. Ed. 2012, 51, 11882. (b) Rupar, P.
A.; Chabanne, L.; Winnik, M. A.; Manners, I. Science 2012, 337, 559.
(12) (a) Hong, Y.; Lam, J. W. Y.; Tang, B. Z. Chem. Soc. Rev. 2011,
40, 5361. (b) An, B.-K.; Lee, D.-S.; Lee, J.-S.; Park, Y.-S.; Song, H.-S.;
Park, S. Y. J. Am. Chem. Soc. 2004, 126, 10232. (d) Zhang, Z.; Xu, B.;
Su, J.; Shen, L.; Xie, Y.; Tian, H. Angew. Chem., Int. Ed. 2011, 50,
11654.
■
The authors declare no competing financial interest.
(13) Thomas, S. W., III; Joly, G. D.; Swager, T. M. Chem. Rev. 2007,
107, 1339.
(14) Chang, J. Y.; Baik, J. H.; Lee, C. B.; Han, M. J.; Hong, S.-K. J.
Am. Chem. Soc. 1997, 119, 3197.
́
(15) (a) Danila, I.; Riobe, F.; Piron, F.; Puigmartí-Luis, J.; Wallis, J.
D.; Linares, M.; Ågren, H.; Beljonne, D.; Amabilino, D. B.; Avarvari, N.
J. Am. Chem. Soc. 2011, 133, 8344. (b) Hess, B.; Kutzner, C.; van der
Spoel, D.; Lindahl, E. J. Chem. Theory Comput. 2008, 4, 435. (c) Zhu,
L.; Li, X.; Wu, S.; Nguyen, K. T.; Yan, H.; Ågren, H.; Zhao, Y. J. Am.
Chem. Soc. 2013, 135, 9174.
(16) (a) Luo, J.; Xie, Z.; Lam, J. W. Y.; Cheng, L.; Chen, H.; Qiu, C.;
Kwok, H. S.; Zhan, X.; Liu, Y.; Zhu, D.; Tang, B. Z. Chem. Commun.
2001, 1740. (b) Wang, Z.; Chen, S.; Lam, J. W. Y.; Qin, W.; Kwok, R.
T. K.; Xie, N.; Hu, Q.; Tang, B. Z. J. Am. Chem. Soc. 2013, 135, 8238.
ACKNOWLEDGMENTS
■
This work was supported by the Research Grant for Talent
Introduction of Fudan University (JJH1717102) and partially
from Columbia University (award number W911NF-12-1-0252
to L. M. Campos). L.Z. thanks Prof. Dr. L. M. Campos and Dr.
K. L. Killops for helpful discussions. X.L. and H.Å. acknowledge
computational resources provided by the Swedish National
Infrastructure for Computing (SNIC) for the project “Multi-
physics Modeling of Molecular Materials”, SNIC 2013/26-31.
REFERENCES
■
(1) (a) Kim, J.-H.; Lee, E.; Jeong, Y.-H.; Jang, W.-D. Chem. Mater.
2012, 24, 2356. (b) Kraabel, B.; Hulin, D.; Aslangul, C.; Lapersonne-
Meyer, C.; Schott, M. Chem. Phys. 1998, 227, 83. (c) Xu, Q.; Lee, S.;
Cho, Y.; Kim, M. H.; Bouffard, J.; Yoon, J. J. Am. Chem. Soc. 2013, 135,
17751. (d) Chen, X.; Kang, S.; Kim, M. J.; Kim, J.; Kim, Y. S.; Kim, H.;
Chi, B.; Kim, S.-J.; Lee, J. Y.; Yoon, J. Angew. Chem., Int. Ed. 2010, 49,
1422.
(2) (a) Patel, G. N.; Walsh, E. K. J. Polym. Sci., Polym. Lett. Ed. 1979,
17, 203. (b) Plachetta, C.; Rau, N. O.; Hauck, A.; Schulz, R. C.
Makromol. Chem., Rapid Commun. 1982, 3, 249.
(17) Levesque, I.; Nea
C.; Daigle, M.; Morin, J.-F. Chem. Sci. 2014, 5, 831.
́ ́ ̀
bo, J. R.; Rondeau-Gagne, S.; Vigier-Carriere,
(18) (a) Okawa, Y.; Aono, M. J. Chem. Phys. 2001, 115, 2317.
(b) Zhang, Q.; Qu, D.-H.; Wu, J.; Ma, X.; Wang, Q.; Tian, H.
Langmuir 2013, 29, 5345.
(19) (a) Chai, J.; Huo, F.; Zheng, Z.; Giam, L. R.; Shim, W.; Mirkin,
C. A. Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 20202. (b) Morikawa, Y.;
Nagano, S.; Watanabe, K.; Kamata, K.; Iyoda, T.; Seki, T. Adv. Mater.
2006, 18, 883.
(3) Zhu, L.; Tran, H.; Beyer, F. L.; Walck, S. D.; Li, X.; Ågren, H.;
Killops, K. L.; Campos, L. M. J. Am. Chem. Soc. 2014, 136, 13381.
(4) (a) Arakawa, Y.; Nakajima, S.; Kang, S.; Konishi, G.-i.; Watanabe,
J. J. Mater. Chem. 2012, 22, 14346. (b) Arakawa, Y.; Kang, S.;
Watanabe, J.; Konishi, G.-i. Chem. Lett. 2014, 43, 1858. (c) Khoo, I. C.;
Webster, S.; Kubo, S.; Youngblood, W. J.; Liou, J. D.; Mallouk, T. E.;
Lin, P.; Hagan, D. J.; Van Stryland, E. W. J. Mater. Chem. 2009, 19,
7525. (d) Thulstrup, P. W.; Hoffmann, S. V.; Hansen, B. K. V.;
Spanget-Larsen, J. Phys. Chem. Chem. Phys. 2011, 13, 16168.
(e) Coates, G. W.; Dunn, A. R.; Henling, L. M.; Dougherty, D. A.;
Grubbs, R. H. Angew. Chem., Int. Ed. Engl. 1997, 36, 248.
(20) (a) Bedner, P.; Niessen, H.; Odermatt, B.; Kretz, M.; Willecke,
K.; Harz, H. J. Biol. Chem. 2006, 281, 6673. (b) Shi, W.; Li, X.; Ma, H.
Angew. Chem., Int. Ed. 2012, 51, 6432.
(21) Park, J.; Park, E.; Kim, A.; Park, S. A.; Lee, Y.; Chi, K. W.; Jung,
Y. H.; Kim, I. S. J. Org. Chem. 2011, 76, 2214.
(5) Wegner, G. Z. Naturforsch. 1969, 246, 824.
(6) (a) Xu, Y.; Smith, M. D.; Geer, M. F.; Pellechia, P. J.; Brown, J.
C.; Wibowo, A. C.; Shimizu, L. S. J. Am. Chem. Soc. 2010, 132, 5334.
(b) Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.; Haddad,
R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.; Shelnutt, J.; Brinker, C. J.
Nature 2001, 410, 913. (c) Sun, A.; Lauher, J. W.; Goroff, N. S. Science
2006, 312, 1030. (d) Yoon, B.; Lee, S.; Kim, J.-M. Chem. Soc. Rev.
2009, 38, 1958. (e) Sun, X.; Chen, T.; Huang, S.; Li, L.; Peng, H.
Chem. Soc. Rev. 2010, 39, 4244. (f) McQuade, D. T.; Pullen, A. E.;
Swager, T. M. Chem. Rev. 2000, 100, 2537.
(7) (a) Kojima, Y.; Tsuji, M.; Matsuoka, T.; Takahashi, H.
Macromolecules 1994, 27, 3735. (b) Lee, S. J.; Park, C. R.; Chang, J.
Y. Langmuir 2004, 20, 9513. (c) Wiley, R. H.; Lee, J. Y. J. Macromol.
Sci., Chem. 1971, 5, 513.
́
(8) (a) Neabo, J. R. o.; Tohoundjona, K. s. I. S.; Morin, J.-F. Org. Lett.
2011, 13, 1358. (b) Diegelmann, S. R.; Hartman, N.; Markovic, N.;
Tovar, J. D. J. Am. Chem. Soc. 2012, 134, 2028. (c) Chan, Y.-H.; Lin, J.-
T.; Chen, I-W P.; Chen, C.-H. J. Phys. Chem. B 2005, 109, 19161.
G
DOI: 10.1021/acs.macromol.5b01488
Macromolecules XXXX, XXX, XXX−XXX