Rational Design of Diphenyldiacetylene-Based Fluorescent Materials Enabling a 365-nm Light-Initiated Topochemical Polymerization

Article abstract of DOI:10.1002/asia.202100468

Photopolymerization of diacetylenes usually requires stringent reaction conditions like high energy irradiation of 254-nm light or even γ-rays, which are generally harmful to the human body and thus mild conditions with lower energy irradiation are requir

Full text of DOI:10.1002/asia.202100468

DOI: 10.1002/asia.202100468
Full Paper
Rational Design of Diphenyldiacetylene-Based Fluorescent
Materials Enabling a 365-nm Light-Initiated Topochemical
Polymerization
Mingjie Zhu and Liangliang Zhu*[a]
Abstract: Photopolymerization of diacetylenes usually re-
quires stringent reaction conditions like high energy irradi-
ation of 254-nm light or even γ-rays, which are generally
harmful to the human body and thus mild conditions with
lower energy irradiation are required. In this study, different
diphenyldiacetylene (DPDA) derivatives were rationally de-
signed followed by the investigation of their photopolymeri-
zation behavior. It was found that the para-substituted amino
groups could render the absorption band of DPDA bath-
ochromically shifted, ensuring a 365-nm light wavelength
coverage. On this basis, an organogel system was constructed
by chemically modifying cholesteryl and lipoic acid onto the
DPDA moiety in aromatic solvents. Such uniform self-
assemblies further facilitated to a rather high degree of
polymerization by 365-nm irradiation. As a kind of fluorescent
materials, the whole polymerization process of this system
can be visualized by a photoluminescent signal.
Introduction
by irradiation or by heat. To be specific, crystal structures with a
°
tilt angle of 45 relative to the diacetylene axis, and a spacing
Polydiacetylenes (PDAs) are usually fabricated through top-
ochemical reaction initiated remotely without any additives.
The well-defined alternating ene-yne conjugated skeleton
allows the resulting materials to exhibit fascinating optical[1]
and electrical[2] properties like chromatism and semi-conductiv-
ity, providing versatile prototypes for applications in cell
imaging,[3] photo-patterning,[4] anti-counterfeiting,[5] information
encryption,[6] photocatalysis,[7] optoelectronic devices,[8] etc. Be-
sides, comprehensive works have also been reported by Prof.
Juyoung Yoon,[9] Prof. Jong-Man Kim[10] and others,[11] where
various aliphatic PDAs are widely functionalized to be used as
chemo/bio sensors since conventional PDAs usually go through
a significant blue-to-red colorimetric transition as well as a non-
fluorescent to fluorescent transition upon external stimuli.
Diphenyldiacetylene (DPDA) has received considerable
attention for its uniqueness such as an extended π-conjugation
structure relative to bare diacetylenes (DAs), along with a larger
intermolecular stacking tendency. Although Wegner had dem-
onstrated the topochemical reactivity of DPDA as far back as
1971,[12] however, successful cases on polymerization of such
aromatized derivatives received far less coverage in contrast
with massive reports on conventional PDAs, probably due to a
more stringent condition for conformational change in the
molecular level. It has been generally acknowledged that the
pre-arrangement of monomers is crucial to perform the 1,4-
addition topochemical transformation for polymerization either
distance of 4.9 Å between two repeating units, are necessary.[13]
Yet, the bulky phenyl rings at both ends enhance the rigidity of
DPDA molecular structures and obstruct the formation of
alternating ene-yne bonds greatly. So far, much effort has been
devoted to aligning DA monomers into such ordered systems
as Langmuir-Blodgett films,[14] crystals,[15] liquid crystals,[16]
monolayers,[17] gels,[18] self-assemblies,[19] and sacrificial tem-
plates like porous materials[20] and block copolymers,[21] relying
on various noncovalent interactions[22] including π-π stacking,[23]
coordination bond,[24] intermolecular hydrogen bond,[25] hydro-
phobic interaction[26] and electrostatic interaction[27] to maintain
an ordered structure. To the best of our knowledge, most of
these strategies were generally conducted by heating, 254-nm
light or even γ-ray irradiation, with only a few reports
concerning the topochemical reaction of aliphatic DAs initiated
under 365-nm light.[28] Unfortunately, such a relatively mild
condition to trigger the topochemical polymerization of DPDA
has remained less explored. In particular, the topochemical
transformation process of DPDA is characterized by a distinctive
photoluminescence enhancement as a result of the enlarged π-
conjugated skeleton, endowing the corresponding polymeric
species with prospective applications as fluorescent materials.
In this work, we aim to rationally design a pure organic
material to attend this goal. Three types of DPDA derivatives
containing ester or amide groups in para- or meta-position
were designed (see Figure 1) for an absorption-band compar-
ison. It is believed that to strengthen the electron-donating
effect with an extended π-conjugation in DPDA can be helpful
to shift its absorption bands bathochromically, ensuring a 365-
nm light wavelength coverage. Cholesterol and (R)-α-lipoic acid
have been widely used as highly efficient components to
construct chiral low molar-mass organic gel[29] with no interfer-
ence with the chromophore. Moreover, organogel systems,
where the reactants are aligned at proximity, are considerably
[a] M. Zhu, Prof. L. Zhu
State Key Laboratory of Molecular Engineering of Polymers
Department of Macromolecular Science
Fudan University
Shanghai 200438 (P. R. China)
E-mail: zhuliangliang@fudan.edu.cn
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/asia.202100468
Chem Asian J. 2021, 16, 1–8
1
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
in all solvents tested rather than gel (Figure S7 and S8, SI),
indicative of the significance of the amide groups and
substitution position for the gelation process. In addition to
altering the absorption band, amide groups are expected to
form intermolecular hydrogen bond and support the construc-
tion of the gel network.
Repeating the heating and cooling process of LAC always
led to similar gels, indicating a reversible sol-gel transition
(Figure 2a and S9, SI). The evidence of hydrogen-bond
formation in LAC gel can be found by concentration-dependent
1H NMR spectroscopy. Chemical shifts of two amide protons go
downfield while the other protons remain untouched (Figure 2b
and Figure S10, SI), until the concentration reaches 3.0 mM. The
lack of hydrogen bond among ester groups led to the failure of
LHC to gel in aromatic solvents as illustrated in 1H NMR
(Figure S12, SI). For mLAC, although the intermolecular hydro-
gen bond exists while monitored by the chemical shifts of
amide protons (Figure S11, SI), the situation was dramatically
contrary when amide groups were introduced in meta-position,
leading to no gelation either. FESEM image showed that large
coils with hierarchical nanostructures were formed rather than
an entangled fibrous network. The difference in molecular
Figure 1. a) Chemical structures of the compounds in this work. b)
Normalized absorption spectra measured in p-xylene by using quartz
cuvettes with a path length of 0.1 mm at a concentration of 0.5 mM.
favorable for the pre-arrangement of monomers for topochem-
ical transformation and polymerization.[30] The synthesis of all
compounds is detailed in the Experimental Section. We
eventually found that the para-substituted amino groups
contained monomer (LAC) can both regulate the absorption
and form a chiral organogel in aromatic solvents, enabling a
365-nm light initiated topochemical polymerization as desired.
Also, the reaction featured a remarkably progressive lumines-
cence enhancement as well as a rather high degree of polymer-
ization.
Results and Discussion
Molecular Design of the DPDA Gelators
Although the substitution of phenyl rings causes an extended
π-conjugation structure in DPDA relative to bare DAs, it still fails
to reach a 365-nm wavelength coverage without an appropriate
further modification. To realize the supposition of photo-
chemical reaction, the priority is to regulate the absorption of
the DPDA derivatives through proper chemical modifications.
Specifically, as illustrated in Figure S1, three types of DPDA
molecular cores were synthesized followed by reactions with
(R)-α-lipoic acid and cholesteryl chloroformate to afford the
compounds used in this work. Figure 1b gives their normalized
absorption spectra originating from the DPDA moiety (com-
pared with Figure S2, SI). One can find that the absorption band
of LAC covers longer-wavelength range than that of mLAC and
LHC since a bathochromic shift of 20 nm was recorded.
Gelation Study in Selective Solvents
Organogels are known to be ideal self-assemblies with
entangled three-dimensional networks for facilitating many
cases of topo-polymerization in gel or xerogel state.[31] Thus,
selective solvent conditions were explored to attempt the
gelation of these DPDA derivatives (see detailed results
presented in Figure S3, SI). It was figured out by optimization
that LAC could gel well in aromatic solvents like toluene, p-
xylene, and o-xylene (Figure S4–S6, SI), with a critical gel
concentration (CGC) as low as 2.0 mM in p-xylene. On the
contrary, mLAC and LHC were found to dissolve or precipitate
Figure 2. a) Photograph showing a reversible sol-gel transition of a LAC gel
in p-xylene upon heating and cooling. b) Concentration-dependent 1H NMR
(400 MHz, toluene-d8, 298 K) of LAC indicating the formation of intermo-
lecular hydrogen bond. c) Temperature-dependent absorption spectra and
d) CD spectra of LAC gel in p-xylene measured by using quartz cuvettes
with a path length of 0.1 mm. The curves were recorded at 25, 45, 75 and
°
85 C, respectively. The absorbance gradually decreased a little while
positive CD signals gradually increased upon cooling.
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
2
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
alignment was supposed to cause the failure of mLAC to gel
(Figure S13, SI). In generally, the driving force of gelation was
mainly attributed to a synergetic effect of intermolecular
hydrogen bond, strong Van der Waals force and π-π stacking.
As hydrogen bond is sensitive to heat and can be rebuilt at low
temperature, heating the gel will weaken the hydrogen bond
and disintegrate the assemblies, whereas cooling brings out an
opposite effect. This thermo reversible sol-gel transition always
occurs in accompany with spectral changes. As shown in
absorption spectra (Figure 2c), the decrease of absorbance as
well as the bathochromic shift of absorption band edge were in
accordance with gel formation when the temperature dropped.
Since both the lipoyl and cholesteryl substituents bear chiral
centers, circular dichroism (CD) spectrum was used to study the
optical activity of LAC gel formed in p-xylene. The molecular
chirality of LAC is approximately absent in the region of 285–
385 nm because the absorption of cholesterol falls in the range
below 250 nm and the Cotton effect of lipoic acid is negligible
due to its rather low extinction coefficient in the region tested
(Figure S14, SI). However, strong supramolecular chirality was
recorded after gelation of LAC (Figure 2d). It has been clarified
in many reports[32] that the self-assembly could cause the
chirality transfer from the chiral groups to achiral moiety. In this
case, Cotton effect with positive signals centered at 295 nm,
310 nm, 340 nm and 365 nm was exhibited due to the chirality
transfer from chiral cholesterol and (R)-α-lipoic acid to DPDA
moiety upon gelation. It should be pointed out that the CD
signals originating from lipoic acid were considered to be
negligible after comparing the CD signal intensities, and these
four positive signals were in good agreement with the
absorption peaks of DPDA moiety as shown in Figure 2c. Upon
heating, the Cotton effect gradually decreased since the
weakened hydrogen bond caused the disassembly of the gel
and greatly hampered the chirality transfer, further proving the
CD signals were induced by employment of hydrogen bond
and molecular stacking. The Cotton effect of LAC gel in toluene
and o-xylene was also observed (Figure S15a, SI). In addition,
the CD spectra of mLAC and LHC in aromatic solvents were
recorded and all the samples remained CD silent as expected,
since no gelation was observed as mentioned above (Fig-
ure S15b and 15c, SI).
Figure 3. a) Concentration-dependent CD spectra of LAC gel in p-xylene
measured in a quartz cuvette with a path length of 0.1 mm. FESEM images
of nanofibrils prepared from samples at b) 1.0 mM, c) 2.0 mM and d) 3.0 mM
by spin coating onto silicon wafers.
(Figure 3a). In this way, discrete helical nanofibrils intertwined
with each other and assembled into a dense fibrous network as
the concentration increased (Figure 3c and 3d), suggesting
strong interfiber interactions. We believe that these findings
may disclose a detailed assembly progression from the micro-
scopic level to some extent.
Photopolymerization Initiated by 365-nm Irradiation
As discussed above, we’ve been successfully realized a great
bathochromic shift of 20 nm in absorption bands compared
with that of LHC and mLAC, along with the well-ordered pre-
arrangement of monomers and through the gelation of LAC. A
portable UV flashlight (λ=365 nm, 5 W) was used then to
initiate the topochemical reaction. Before irradiation, this white
translucent gel only showed dim blue light under 365-nm
illumination as indicated by the emission and excitation spectra
(Figure 4a and S16, SI). Along with prolonging the irradiation
time, a remarkable change in photoluminescence could be
observed with the naked eye by giving out bright yellow light
(Figure 4b, λex =365 nm).
Molecular Alignment Study
During this process, a gradually increased emission intensity
and a bathochromic shift can be clearly recorded (Figure 4c).
The emission band centered at 475 nm shifted to 550 nm with
the band edge extended to 725 nm or even longer. This
dynamic progress reflected the progressive enlargement of π-
conjugated skeleton upon photopolymerization. The reaction
reached its equilibrium within 10 minutes while further pro-
longing the irradiation time to 30 minutes caused a slight
hypsochromic shift again, probably due to the occurrence of
photodegradation or photobleaching (Figure S17, SI). The
efficiency can be further improved once an optimized light
source could be applied. By altering the excitation wavelength,
emission bands of various intensity or center wavelength were
Though lower than CGC, four CD signals appeared when the
concentration increased from 0.75 mM to 1.0 mM, indicating
that molecules have already started to assemble (Figure 3a).
Meanwhile, one-dimensional nanofibrils of several micrometers
in length and a few tens of nanometers in diameter were
observed via field emission scanning electron microscope
(FESEM, see Figure 3b). Upon further increasing the concen-
tration to 3.0 mM, bathochromic shifts of 5 nm were clearly
recorded in CD signals, suggesting a higher degree of π-
conjugation and a better coplanarity. This spectral change
reflected that the DPDA units aligned into a one-dimensional
array of molecules for facilitating the topochemical progress
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
3
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
(Figure 4f). Such disintegration process has been observed
before, mainly attributed to a significant conformational change
of bulky phenyl rings and the formation of π-conjugated
skeleton disturbing the hydrogen bond network.[18a,33] Similar to
the cases reporting the enantioselective photopolymerization
of aliphatic diacetylenes,[34] the helical architecture in our case is
definitely crucial to the bond-breaking and bond-making since
the polymerization occurred along with a loss of chiral gel. As
for the 2.0 mM and 1.0 mM samples, the rather loose stacking
mode not only disturbed the chirality transfer, but hampered
the polymerization also. Compared with 3.0 mM samples, after
the same time of irradiation, emission bands at short wave-
length when excited by 385 nm and below can be found. Due
to a relatively weak π-electron delocalization, oligomers of
DPDA derivatives usually possess emission bands at short
27b]
wavelength, usually around 420 nm.[19a,20a,
The observed
emission bands centered at 440 nm represented the formation
of oligomeric species. Meanwhile, the relatively weak emission
excited by 488 nm also indicated a lower content or absence of
high polymers (Figure S21, SI). Of course, a THF solution of LAC
resulted in an even less efficiency of the photopolymerization
(only a little bit of oligomerization was indicated by a series of
optical study, see Figure S22 and S23, SI).
Figure 4. a–b) Photos of LAC gel (3.0 mM) in p-xylene with or without
irradiation taken under day light or 365-nm light. Polymerization progress is
monitored by c) emission spectra (λex =405 nm). d) The altering of excitation
wavelength to 488 nm that to confirm the existence of high polymeric
species after 10 min of irradiation. Polymerization progress monitored by e)
absorption and f) CD spectra. Emission band centered at 550 nm and
increase of absorption in the region of 370–440 nm both indicate a high
degree of polymerization.
Gel Transformation with Fluorescent Visualization
Thanks to such a longer-wavelength initiation, the topochem-
ical reaction could be efficiently achieved in a glass vial.
Figure 5a presents a series of photos captured from a time-
lapse video (see Video, SI) recording the photopolymerization
to visualize the transformation progress macroscopically. It
should be noted that owing to the compact structure of gel,
however, it was difficult for the light to penetrate a thick gel
and the photopolymerization would be confined to the bottom
(Figure S24, SI). Therefore, in order to reduce the effect of gel
thickness, photopolymerization in an inverted quartz cuvette
was carried out to picture the collapse of gel in motion. We can
see that the yellow fluorescence extended from the edge to the
center, which got brighter progressively upon irradiation. When
the reaction went on to a certain extent, the hydrogen bond
presented (Figure 4d and S18, SI). Since an enlarged π-
conjugated structure, originating from a higher degree of
polymerization, usually possesses a longer-wavelength excita-
tion, a prominent emission band centered at 585 nm when
excited by 488 nm clearly indicated the existence of high
polymer species.
The reduced original absorption band of the monomer and
the progressive increase of absorbance in the region of 370–
440 nm (Figure 4e), resulting from the enlarged π-conjugated
structure, also confirmed the photopolymerization process.
Raman spectra showed that the peak at 2213 cmÀ 1 attributed to
the stretching of diacetylene was reduced after irradiation.
Simultaneously, the formation of ene-yne unit associated with
phenyl rings can be observed from the broad band centered at
1579 cmÀ 1 (Figure S20, SI). In addition to the spectrometry
methods, gel permeation chromatography results (Figure S19,
SI) gave more solid evidence of the coexistence of polymer
species with different degrees of polymerization from lower to
higher. The number of repeating units was observed to exceed
10 in the highest molecular weight species. Thus, it can be
concluded that this uniform gel network leads to a rather high
degree of polymerization of diphenyldiacetylene-based fluores-
cent materials. As the polymerization proceeds, the originally
stable gel began to disassemble. Therefore, CD signals gradually
disappeared during the whole process, suggesting the polymer-
ization occurred together with a loss of the gel network
Figure 5. a) Images captured from a time-lapse video recording the photo-
polymerization process carried out in a glass vial irradiated by a 365 nm
flashlight from the bottom. b) Images presenting the photopolymerization
process of LAC gel in an inverted quartz cuvette with a path length of 1 mm
irradiated by a 365-nm flashlight from the side.
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
4
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
Photopolymerization. Photopolymerization was performed by
irradiation with a UV flashlight (λ=365 nm, 5 W) at a distance of
1 cm from the cell. The progress of the reaction was monitored by
UV-vis spectra, emission spectra and CD spectra at different time
intervals.
network was disassembled and the gel collapsed to the ground
as circled in Figure 5b. These results clearly visualized a gel
transformation process along with the photopolymerization.
Synthesis of APDA (C16H12N2). APDA was synthesized from 4-
ethynylaniline according to a similar procedure described in the
literature.[35] 1H NMR (400 MHz, DMSO-d6, 298 K): δ 7.23–7.18 (m,
4H), 6.55–6.51 (m, 4H), 5.73 (s, 4H). 13C NMR (101 MHz, DMSO-d6,
298 K): δ 150.62, 133.99, 114.03, 106.86, 83.37, 72.48. MS (Maldi-
ToF): calcd for [M+] m/z=232.10, found m/z: 232.1772.
Conclusion
In summary, a universal strategy to rationally design fluorescent
materials enabling a 365-nm light-initiated topochemical poly-
merization was demonstrated here. Through chemical modifica-
tion of para-substituted amide groups on the phenyl rings, the
absorption bands of DPDA moiety were rendered bathochromi-
cally shifted to longer wavelength. On this basis, in situ
topochemical reaction initiated by 365 nm was successfully
conducted upon the gelation of monomers. Intermolecular
hydrogen bond plays a key role for pre-arrangement of the
light-active reactants. The gel network composed of helical
nanofibrils was believed to situate the reactive moiety in a
serviceable position for facilitating the 1,4-addition polymer-
ization, leading to a rather high degree of polymerization. This
strategy, achieved under a rather mild conditions, could be
monitored facilely by spectrometric methods as well as the
Synthesis of LA (C24H24N2OS2). (R)-α-lipoic acid (0.2491 g,
1.2 mmol), HATU (0.4790 g, 1.3 mmol) and DIPEA (0.5 mL, 3 mmol)
°
were dissolved in 20 mL DMF. After 30 min of pre-reaction at 0 C,
the mixed solution was added dropwise into APDA (0.2474 g,
1.1 mmol) solution in DMF (5 mL). The mixture was allowed to react
°
at 45 C for 4 h under N2. The solution was diluted with 100 mL
chloroform and then washed by NaHCO3 sat. solution, HCl and NaCl
sat. solution in sequence. The organic layer was collected and dried
by anhydrous Na2SO4 overnight. Compound LA was purified by
silica gel chromatography (PE/EA=4:1) to obtain yellow powder
(0.2845 g, 61.5%). 1H NMR (400 MHz, DMSO-d6, 298 K): δ 10.11 (s,
1H), 7.71–7.58 (m, 2H), 7.55–7.42 (m, 2H), 7.30–7.18 (m, 2H), 6.60–
6.49 (m, 2H), 5.79 (s, 2H), 3.64 (dq, J=8.7, 6.2 Hz, 1H), 3.24–3.08 (m,
2H), 2.42 (dt, J=18.5, 6.4 Hz, 1H), 2.34 (t, J=7.3 Hz, 2H), 1.94–1.82
(m, 1H), 1.76–1.52 (m, 4H), 1.41 (dt, J=14.1, 7.2 Hz, 2H). 13C NMR
(101 MHz, DMSO-d6, 298 K): δ 171.90, 151.00, 140.71, 134.25, 133.34,
119.34, 115.52, 114.04, 106.14, 84.53, 81.48, 74.31, 71.89, 56.55,
40.39, 38.57, 36.77, 34.61, 28.78, 25.22. MS (Maldi-ToF): calcd for
[M+] m/z=420.13, found m/z: 420.2525.
naked eye, accompanied by
a remarkable luminescence
enhancement in response to the enlarged π-conjugated
structure and the gel disassembly as the polymerization
proceeds. We anticipate that the establishment of such a
methodology could be valuable for further study on latent
application of topochemical materials.
Synthesis of LAC (C52H68N2O3S2). The solution of LA (0.2104 g,
0.5 mmol), cholesteryl chloroformate (0.1690 g, 0.8 mmol) and Et3N
(0.5 mL, 3.6 mmol) in THF (10 mL) was refluxed overnight under N2.
Solvent was removed by rotary evaporator, and pale-yellow powder
was obtained (0.2196 g, 52.7%) through silica gel chromatography
Experimental Section
1
(PE/DCM=1:1). H NMR (400 MHz, DMSO-d6, 298 K): δ 10.12 (s, 1H),
General. Chemical reagents and solvents were all commercially
available and used as received. H NMR and 13C NMR spectra were
1
9.93 (s, 1H), 7.65 (d, J=8.8 Hz, 2H), 7.57–7.47 (m, 6H), 5.39 (s, 1H),
4.47 (dd, J=13.7, 9.1 Hz, 1H), 3.68–3.58 (m, 1H), 3.15 (ddt, J=30.5,
11.0, 6.8 Hz, 2H), 2.47–2.29 (m, 5H), 2.05–1.78 (m, 6H), 1.75–1.28 (m,
17H), 1.10 (dd, J=17.9, 9.6 Hz, 6H), 0.97 (d, J=18.3 Hz, 6H), 0.93–
0.80 (m, 10H), 0.66 (s, 3H). 13C NMR (101 MHz, CDCl3, 298 K): δ
170.98, 152.62, 139.42, 138.94, 138.59, 133.50, 133.39, 122.93,
119.33, 118.11, 117.29, 116.15, 81.51, 81.17, 75.33, 73.79, 73.42,
56.67, 56.37, 56.12, 49.98, 42.31, 40.28, 39.71, 39.52, 38.51, 38.40,
37.52, 36.93, 36.57, 36.18, 35.82, 34.64, 31.91, 31.86, 28.85, 28.25,
28.05, 28.03, 25.12, 24.30, 23.85, 22.85, 22.59, 21.05, 19.35, 18.73,
measured on a Bruker 400 MHz spectrometer. MS was measured by
Matrix Assisted Laser Desorption Ionization-Time of Flight (Maldi-
ToF) Mass Spectrometer (AB SCIEX 5800) using default Reflector
Positive mode, with DCTB as the matrix. UV-vis absorption spectra
were recorded in quartz cuvettes with a path length of 0.1 mm on
a Shimadzu 1800 spectrophotometer. Emission spectra were taken
in quartz cuvettes with a path length of 1 mm with an Edinburgh
FLS1000 spectrofluorometer. Circular Dichroism (CD) spectra were
recorded in quartz cuvettes with a path length of 0.1 mm on a
Chirascan qCD. Raman spectra were recorded using XploRA Raman
spectrometer. Field emission scanning electron microscope (FESEM)
was performed on a Zeiss Gemini SEM500. Samples were prepared
by spin coating onto silicon wafers and coated with a thin layer of
Au to increase contrast. The polymeric species were analyzed with
Agilent 1260 gel permeation chromatography (GPC) equipped with
a UV detector and calibrated with polystyrene standard samples.
THF was used as the eluent. See supporting information for the
synthesis scheme pertaining to the compound labels.
+
11.88. MS (Maldi-ToF): calcd for [M+K] m/z=871.43, found m/z:
871.2699.
Synthesis of mAPDA (C16H12N2). mAPDA was synthesized from 3-
1
ethynylaniline in the same way as APDA. H NMR (400 MHz, DMSO-
d6, 298 K): δ 7.06 (t, J=7.8 Hz, 2H), 6.71 (dt, J=2.3, 1.5 Hz, 4H), 6.66
(ddd, J=8.1, 2.2, 1.0 Hz, 2H), 5.32 (s, 4H). 13C NMR (101 MHz, DMSO-
d6, 298 K): δ 149.37, 129.85, 121.14, 120.21, 117.09, 116.16, 82.77,
72.83. MS (Maldi-ToF): calcd for [M+] m/z=232.10, found m/z:
232.0432.
Gelation in Organic Solvents. A typical procedure for gel formed in
aromatic solvents including toluene, p-xylene and o-xylene is
described as follows: LAC was suspended in the solvents in a sealed
Synthesis of mLAC (C52H68N2O3S2). Synthetic route of mLAC was
similar to that of LAC except for the starting compound mAPDA.
After reaction of mAPDA with (R)-α-lipoic acid and cholesteryl
chloroformate successively, white powder mLAC was obtained
through silica gel chromatography (PE/EA=4:1). 1H NMR (400 MHz,
DMSO-d6, 298 K): δ 10.07 (s, 1H), 9.85 (s, 1H), 7.90 (s, 1H), 7.72–7.54
(m, 3H), 7.31 (ddd, J=26.1, 17.3, 7.9 Hz, 4H), 5.40 (s, 1H), 4.48 (s,
1H), 3.64 (td, J=12.1, 6.1 Hz, 1H), 3.25–3.08 (m, 2H), 2.45–2.30 (m,
°
glass vial and gently heated at 80–90 C until a transparent solution
was obtained. After spontaneous cooling to room temperature, gel
was formed with no gravitational flow upon inversion of the vial. To
be specific, the concentration was 3 mM for p-xylene and 6 mM for
toluene and o-xylene.
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
5
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
[3] a) H. Jiang, X. Y. Hu, S. Schlesiger, M. Li, E. Zellermann, S. K. Knauer, C.
Schmuck, Angew. Chem. Int. Ed. Engl. 2017, 56, 14526–14530; b) Y. K.
Jung, M. A. Woo, H. T. Soh, H. G. Park, Chem. Commun. 2014, 50, 12329–
12332.
[4] a) Y. K. Jung, C. Jung, H. G. Park, ACS Appl. Mater. Interfaces 2016, 8,
15684–15690; b) D. J. Ahn, J. M. Kim, Acc. Chem. Res. 2008, 41, 805–816.
[5] Y. J. Choi, S. Park, W. J. Yoon, S. I. Lim, J. Koo, D. G. Kang, S. Park, N. Kim,
K. U. Jeong, Adv. Mater. 2020, 32, 2003980.
[6] J. Lee, S. Seo, J. Kim, ACS Appl. Mater. Interfaces 2018, 10, 3164–3169.
[7] a) S. Kim, S. Lee, T. F. Anjong, H. Y. Jang, J. Y. Kim, C. Lee, S. Park, H. J.
Lee, J. Yoon, J. Kim, J. Phys. Chem. C 2016, 120, 28407–28414; b) L. Xia,
B. F. Cheng, T. Y. Zeng, X. Nie, G. Chen, Z. Zhang, W. J. Zhang, C. Y.
Hong, Y. Z. You, Adv. Sci. 2020, 7, 1902451.
[8] a) N. Pootrakulchote, C. Reanprayoon, J. Gasiorowski, N. S. Sariciftci, P.
Thamyongkit, New J. Chem. 2015, 39, 9228–9233; b) M. A. Desta, C.-W.
Liao, S.-S. Sun, Chem. Asian J. 2017, 12, 690–697; c) J. Nishide, T.
Oyamada, S. Akiyama, H. Sasabe, C. Adachi, Adv. Mater. 2006, 18, 3120–
3124.
[9] a) X. Chen, G. Zhou, X. Peng, J. Yoon, Chem. Soc. Rev. 2012, 41, 4610–
4630; b) S. Lee, J. Y. Kim, X. Chen, J. Yoon, Chem. Commun. 2016, 52,
9178–9196; c) H. N. Kim, Z. Guo, W. Zhu, J. Yoon, H. Tian, Chem. Soc. Rev.
2011, 40, 79–93.
[10] a) O. Yarimaga, J. Jaworski, B. Yoon, J. M. Kim, Chem. Commun. 2012, 48,
2469–2485; b) D. H. Park, J. Hong, I. S. Park, C. W. Lee, J. M. Kim, Adv.
Funct. Mater. 2014, 24, 5186–5193; c) S. Chae, J. P. Lee, J. M. Kim, Adv.
Funct. Mater. 2016, 26, 1769–1776.
[11] a) X. Qian, B. Städler, Adv. Funct. Mater. 2020, 30, 2004605; b) X. M. Qian,
C. Gargalo, K. V. Gernaey, B. Stadler, ACS Appl. Nano Mater. 2020, 3,
3439–3448; c) X. M. Qian, B. Stadler, Chem. Mater. 2019, 31, 1196–1222.
[12] G. Wegner, J. Polym. Sci., Part B: Polym. Lett. 1971, 9, 133–144.
[13] Z. Li, F. W. Fowler, J. W. Lauher, J. Am. Chem. Soc. 2009, 131, 634–643.
[14] a) L. Zhong, X. Zhu, P. Duan, M. Liu, J. Phys. Chem. B 2010, 114, 8871–
8878; b) X. Huang, M. Liu, Chem. Commun. 2003, 66–67; c) Y. Xu, J. Li, W.
Hu, G. Zou, Q. Zhang, J. Colloid Interface Sci. 2013, 400, 116–122.
[15] a) Y. Xu, M. D. Smith, M. F. Geer, P. J. Pellechia, J. C. Brown, A. C.
Wibowo, L. S. Shimizu, J. Am. Chem. Soc. 2010, 132, 5334–5335;
b) W. W. L. Xu, M. D. Smith, J. A. Krause, A. B. Greytak, S. G. Ma, C. M.
Read, L. S. Shimizu, Cryst. Growth Des. 2014, 14, 993–1002; c) J. W.
Lauher, F. W. Fowler, N. S. Goroff, Acc. Chem. Res. 2008, 41, 1215–1229.
[16] a) J. Y. Chang, J. R. Yeon, Y. S. Shin, M. J. Han, S. K. Hong, Chem. Mater.
2000, 12, 1076–1082; b) Y. Xu, H. Jiang, Q. Zhang, F. Wang, G. Zou,
Chem. Commun. 2014, 50, 365–367.
5H), 2.01–1.77 (m, 6H), 1.71–1.29 (m, 17H), 1.10 (d, J=18.7 Hz, 6H),
0.98 (d, J=17.1 Hz, 6H), 0.94–0.82 (m, 10H), 0.67 (s, 3H). 13C NMR
(101 MHz, CDCl3, 298 K): δ 171.00, 152.85, 139.49, 138.22, 137.95,
129.22, 128.38, 127.44, 123.30, 122.88, 122.40, 122.09, 120.79,
119.53, 81.34, 81.09, 75.26, 74.14, 73.95, 56.68, 56.37, 56.12, 49.99,
42.32, 40.27, 39.73, 39.52, 38.51, 38.41, 37.45, 36.95, 36.58, 36.19,
35.81, 34.66, 31.92, 31.87, 28.85, 28.25, 28.06, 28.03, 25.16, 24.30,
23.84, 22.85, 22.58, 21.05, 19.35, 18.73, 11.88. MS (Maldi-ToF): calcd
+
+
for [M+K]
m/z=871.43, found m/z: 871.3015; [M+Na]
=
855.46, found m/z=855.3115.
Synthesis of HPDA (C16H10O2). HPDA was synthesized according to
the procedure described in the literature.[36] 1H NMR (400 MHz,
DMSO-d6, 298 K): δ 10.13 (s, 2H), 7.41 (d, J=8.8 Hz, 4H), 6.79 (d, J=
8.8 Hz, 4H). 13C NMR (101 MHz, DMSO-d6, 298 K): δ 159.36, 134.57,
116.38, 111.18, 82.29, 72.76. MS (Maldi-ToF): calcd for [M+] m/z
=234.07, found m/z: 234.2119.
Synthesis of LHC (C52H66O5S2). Synthetic route of LHC was similar
to that of LAC except for the starting compound HPDA. After
reaction of HPDA with (R)-α-lipoic acid and cholesteryl chlorofor-
mate successively, white powder LHC was obtained through silica
gel chromatography (PE/DCM=2:1). 1H NMR (400 MHz, CDCl3,
298 K): δ 7.53 (dd, J=6.6, 4.7 Hz, 4H), 7.18 (d, J=8.7 Hz, 2H), 7.07 (d,
J=8.6 Hz, 2H), 5.43 (s, 1H), 4.58 (dt, J=10.5, 5.1 Hz, 1H), 3.60 (dt, J=
13.0, 6.5 Hz, 1H), 3.25–3.08 (m, 2H), 2.59 (t, J=7.3 Hz, 2H), 2.54–2.41
(m, 3H), 2.07–1.83 (m, 6H), 1.81–1.59 (m, 7H), 1.52–1.40 (m, 5H), 1.33
(dd, J=22.6, 15.4 Hz, 5H), 1.18–1.09 (m, 6H), 1.05–0.97 (m, 6H), 0.92
(d, J=6.5 Hz, 3H), 0.86 (dd, J=6.6, 1.7 Hz, 7H), 0.68 (s, 3H). 13C NMR
(101 MHz, CDCl3, 298 K): δ 171.52, 152.42, 151.58, 151.23, 139.02,
133.78, 133.76, 123.32, 121.90, 121.37, 119.38, 119.27, 80.86, 80.71,
79.22, 74.01, 73.91, 56.67, 56.29, 56.11, 49.96, 42.32, 40.26, 39.70,
39.52, 38.54, 37.90, 36.81, 36.55, 36.18, 35.80, 34.61, 34.13, 31.92,
31.83, 28.71, 28.24, 28.03, 27.62, 24.57, 24.29, 23.83, 22.85, 22.58,
+
21.06, 19.30, 18.73, 11.88. MS (Maldi-ToF): calcd for [M+K] m/z=
874.18, found m/z: 874.4517.
Acknowledgements
[17] a) F. L. Wu, N. V. S. D. K. Bhupathiraju, A. Brown, Z. T. Liu, C. M. Drain,
J. D. Batteas, J. Phys. Chem. C 2020, 124, 4081–4089; b) F. Xie, C. F. Chen,
J. Chen, M. H. Liu, J. Photochem. Photobiol. A 2018, 355, 283–289; c) Y. H.
Chan, J. T. Lin, I. W. Chen, C. H. Chen, J. Phys. Chem. B 2005, 109, 19161–
19168.
This work was financially supported by 2019 NSFC (21975046) and
partially from the National Key Research and Development
Program of China (2017YFA0207700).
[18] a) J. R. Neabo, K. I. Tohoundjona, J. F. Morin, Org. Lett. 2011, 13, 1358–
1361; b) G. Wang, N. Goyal, H. P. Mangunuru, H. Yang, S. Cheuk, P. V.
Reddy, J. Org. Chem. 2015, 80, 733–743; c) Y. J. Choi, D. Jung, S. I. Lim,
W. J. Yoon, D. Y. Kim, K. U. Jeong, ACS Appl. Mater. Interfaces 2020, 12,
33239–33245; d) Y. Xu, S. Fu, F. Liu, H. Yu, J. Gao, Soft Matter 2018, 14,
8044–8050; e) S. R. Diegelmann, N. Hartman, N. Markovic, J. D. Tovar, J.
Am. Chem. Soc. 2012, 134, 2028–2031; f) S. Li, L. Zhang, J. Jiang, Y.
Meng, M. Liu, ACS Appl. Mater. Interfaces 2017, 9, 37386–37394.
[19] a) L. Zhu, M. T. Trinh, L. Yin, Z. Zhang, Chem. Sci. 2016, 7, 2058–2065;
b) L. L. Zhu, X. Li, S. N. Sanders, H. Agren, Macromolecules 2015, 48,
5099–5105; c) M. J. Zhu, L. Y. Yin, Y. Y. Zhou, H. W. Wu, L. L. Zhu,
Macromolecules 2018, 51, 746–754; d) S. Rondeau-Gagne, J. R. Neabo,
M. Desroches, J. Larouche, J. Brisson, J. F. Morin, J. Am. Chem. Soc. 2013,
135, 110–113; e) J. Q. Fan, X. Xu, W. Yu, Z. H. Wei, D. Q. Zhang, Polym.
Chem. 2020, 11, 1947–1953; f) M. N. Tahir, A. Nyayachavadi, J. F. Morin,
S. Rondeau-Gagne, Polym. Chem. 2018, 9, 3019–3028.
Conflict of Interest
The authors declare no conflict of interest.
Keywords: diphenyldiacetylene
·
topochemical
polymerization · organogel · hydrogen bond · fluorescent
materials
[20] a) Y. I. Fujiwara, K. Kadota, S. S. Nagarkar, N. Tobori, S. Kitagawa, S.
Horike, J. Am. Chem. Soc. 2017, 139, 13876–13881; b) N. Kameta, W.
Ding, M. Masuda, Chem. Commun. 2021, 57, 464–467.
[21] a) L. Zhu, H. Tran, F. L. Beyer, S. D. Walck, X. Li, H. Agren, K. L. Killops,
L. M. Campos, J. Am. Chem. Soc. 2014, 136, 13381–13387; b) D. Krishnan,
R. B. A. Raj, E. B. Gowd, Polym. Chem. 2019, 10, 3154–3162.
[22] J. P. Huo, Q. J. Deng, T. Fan, G. Z. He, X. H. Hu, X. X. Hong, H. Chen, S. H.
Luo, Z. Y. Wang, D. C. Chen, Polym. Chem. 2017, 8, 7438–7445.
[23] G. Shin, M. I. Khazi, J.-M. Kim, Macromolecules 2019, 53, 149–157.
[24] M. N. Tahir, E. Abdulhamied, A. Nyayachavadi, M. Selivanova, S. H.
Eichhorn, S. Rondeau-Gagne, Langmuir 2019, 35, 15158–15167.
[1] a) X. Sun, T. Chen, S. Huang, L. Li, H. Peng, Chem. Soc. Rev. 2010, 39,
4244–4257; b) A. Sarkar, S. Okada, H. Matsuzawa, H. Matsuda, H.
Nakanishi, J. Mater. Chem. 2000, 10, 819–828.
[2] a) B. P. Krishnan, S. Mukherjee, P. M. Aneesh, M. A. Namboothiry, K. M.
Sureshan, Angew. Chem. Int. Ed. Engl. 2016, 55, 2345–2349; b) M.
Ulaganathan, R. V. Hansen, N. Drayton, H. Hingorani, R. G. Kutty, H.
Joshi, S. Sreejith, Z. Liu, J. Yang, Y. Zhao, ACS Appl. Mater. Interfaces
2016, 8, 32643–32648; c) S. Cho, G. Han, K. Kim, M. M. Sung, Angew.
Chem. Int. Ed. 2011, 50, 2742–2746; Angew. Chem. 2011, 123, 2794–
2798.
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
6
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
[25] a) E. Jahnke, I. Lieberwirth, N. Severin, J. P. Rabe, H. Frauenrath, Angew.
Chem. Int. Ed. Engl. 2006, 45, 5383–5386; b) P. Tanphibal, K. Tashiro, S.
Chirachanchai, Macromol. Rapid Commun. 2016, 37, 685–690; c) Y.
Meng, J. Jiang, M. Liu, Nanoscale 2017, 9, 7199–7206; d) S. M. Curtis, N.
Le, F. W. Fowler, J. W. Lauher, Cryst. Growth Des. 2005, 5, 2313–2321.
[26] Y. Lu, Y. Yang, A. Sellinger, M. Lu, J. Huang, H. Fan, R. Haddad, G. Lopez,
A. R. Burns, D. Y. Sasaki, J. Shelnutt, C. J. Brinker, Nature 2001, 410, 913–
917.
[27] a) S. Wu, L. Pan, Y. Huang, N. Yang, Q. Zhang, Soft Matter 2018, 14,
6929–6937; b) X. Y. Jia, M. J. Zhu, Q. Bian, B. B. Yue, Y. P. Zhuang, B. Wu,
L. Yu, J. D. Ding, J. J. Zhang, L. L. Zhu, Macromolecules 2018, 51, 8038–
8045.
[28] a) Y. Wang, L. Li, K. Yang, L. A. Samuelson, J. Kumar, J. Am. Chem. Soc.
2007, 129, 7238–7239; b) S. Wang, Y. Li, H. Liu, J. Li, T. Li, Y. Wu, S.
Okada, H. Nakanishi, Org. Biomol. Chem. 2015, 13, 5467–5474.
[29] a) D. A. Stone, L. Hsu, N. R. Wheeler, E. Wilusz, W. Zukas, G. E. Wnek,
L. T. J. Korley, Soft Matter 2011, 7, 2449–2455; b) M. H. Liu, G. H. Ouyang,
D. Niu, Y. T. Sang, Org. Chem. Front. 2018, 5, 2885–2900; c) P. Xing, H.
Chen, L. Bai, A. Hao, Y. Zhao, ACS Nano 2016, 10, 2716–2727; d) S.
Shinkai, K. Murata, J. Mater. Chem. 1998, 8, 485–495.
[31] a) B. P. Krishnan, K. M. Sureshan, J. Am. Chem. Soc. 2017, 139, 1584–
1589; b) B. P. Krishnan, S. Ramakrishnan, K. M. Sureshan, Chem.
Commun. 2013, 49, 1494–1496.
[32] a) L. Zhang, T. Wang, Z. Shen, M. Liu, Adv. Mater. 2016, 28, 1044–1059;
b) M. Liu, L. Zhang, T. Wang, Chem. Rev. 2015, 115, 7304–7397; c) P.
Duan, H. Cao, L. Zhang, M. Liu, Soft Matter 2014, 10, 5428–5448.
[33] O. J. Dautel, M. Robitzer, J. P. Lere-Porte, F. Serein-Spirau, J. J. Moreau, J.
Am. Chem. Soc. 2006, 128, 16213–16223.
[34] a) J. Kim, J. Lee, W. Y. Kim, H. Kim, S. Lee, H. C. Lee, Y. S. Lee, M. Seo, S. Y.
Kim, Nat. Commun. 2015, 6, 6959; b) Y. Xu, G. Yang, H. Xia, G. Zou, Q.
Zhang, J. Gao, Nat. Commun. 2014, 5, 5050; c) C. He, Z. Feng, S. Shan, M.
Wang, X. Chen, G. Zou, Nat. Commun. 2020, 11, 1188; d) C. Chen, J.
Chen, T. Wang, M. Liu, ACS Appl. Mater. Interfaces 2016, 8, 30608–30615.
[35] I. Yamaguchi, H. Higashi, S. Kimura, M. Sato, Helv. Chim. Acta 2010, 93,
819–828.
[36] J. Park, E. Park, A. Kim, S. A. Park, Y. Lee, K. W. Chi, Y. H. Jung, I. S. Kim, J.
Org. Chem. 2011, 76, 2214–2219.
Manuscript received: April 30, 2021
[30] a) R. Mohanrao, K. Hema, K. M. Sureshan, ACS Appl. Polym. Mater. 2020,
2, 4985–4992; b) B. P. Krishnan, S. Raghu, S. Mukherjee, K. M. Sureshan,
Chem. Commun. 2016, 52, 14089–14092.
Revised manuscript received: May 29, 2021
Accepted manuscript online: June 1, 2021
Version of record online: ■■■, ■■■■
Chem Asian J. 2021, 16, 1–8
www.chemasianj.org
7
© 2021 Wiley-VCH GmbH
��
These are not the final page numbers!

Full Paper
FULL PAPER
A universal strategy to rationally
design diphenyldiacetylene-based
fluorescent materials enabling a
365-nm light-initiated topochemical
polymerization is demonstrated here.
Through chemical modification of
para-substituted amide groups and
construction of gel networks, the
reaction featured a remarkably pro-
gressive luminescence enhancement
and gel disassembly upon irradiation,
leading to a rather high degree of
polymerization.
M. Zhu, Prof. L. Zhu*
1 – 8
Rational Design of Diphenyldiacety-
lene-Based Fluorescent Materials
Enabling a 365-nm Light-Initiated
Topochemical Polymerization