Remarkable isomeric effects on the mechanofluorochromism of tetraphenylethylene-based D-π-A derivatives

Article abstract of DOI:10.1039/c8nj05933k

Three tetraphenylethylene (TPE) decorated benzaldehyde isomers were designed and synthesized via the Suzuki-Miyaura coupling reaction with higher yields by changing the linking positions of the peripheral TPE units to demonstrate the isomeric effects on t

Full text of DOI:10.1039/c8nj05933k

NJC
View Article Online
View Journal
PAPER
Remarkable isomeric effects on the
mechanofluorochromism of
Cite this:DOI: 10.1039/c8nj05933k
tetraphenylethylene-based D–p–A derivatives†
Junhui Jia * and Haixia Zhao
Three tetraphenylethylene (TPE) decorated benzaldehyde isomers were designed and synthesized via the
Suzuki–Miyaura coupling reaction with higher yields by changing the linking positions of the peripheral
TPE units to demonstrate the isomeric effects on the photophysical and MFC properties. The changes of
the linking positions could alter the molecular packing modes, and thus, their solid-state fluorescence
properties exhibit remarkable isomeric effects. Interestingly, the three isomers are all aggregation
induced emission (AIE) and MFC dyes. And the MFC activities of the three compounds are increased with
the sequence of m-TPEC (45 nm) 4 p-TPEC (39 nm) 4 o-TPEC (8 nm). X-ray structural analysis, XRD,
DSC and theoretical studies suggest that the change from a crystalline phase with a twisted molecular
structure to a more planar amorphous phase should be responsible for the MFC properties. These
findings suggest that subtle manipulation of the end groups capped at benzaldehyde could significantly
alter and tune the photophysical properties. And these results will be of great help in understanding the
structure–property relationships of MFC mechanisms and designing more new MFC materials.
Received 22nd November 2018,
Accepted 2nd January 2019
DOI: 10.1039/c8nj05933k
rsc.li/njc
their applications. This situation was greatly improved by the
important discovery of the aggregation induced emission (AIE)
Introduction
Organic solid luminescent materials are being widely investi- phenomenon by Tang et al. in 2001.7 The luminogens with the
gated for their potential applications in optoelectronic and bio- AIE feature usually show strong fluorescence upon aggregation,
logical fields, such as organic light-emitting diodes (OLEDs),1 which is beneficial for the acquisition of high-contrast mechano-
bioimaging,2 chemo/biosensors,3 DSSCs4 and so on. Moreover, chromic luminescent materials. Recently, a lot of organic fluores-
some organic materials can perceive changes in the surround- cent small molecules have been designed to simultaneously
ing environment, and make corresponding responses through exhibit AIE and MFC properties.8 However, to date, organic
dynamic and reversible fluorescence and color conversion. luminescent small molecules exhibiting mechanofluorochromic
Among these luminogens, mechanofluorochromic (MFC) characteristics with AIE are still insufficient, and designing and
materials, the emissions of which can be repeatedly switched synthesizing such compounds containing the two properties is
between different colors under external force stimuli such as meaningful and challenging. It is common knowledge that solid-
grinding, pressing, shearing, smearing, or crushing, have received state optical properties strongly depend on molecular packing
considerable attention in the construction of mechanical sensors, arrangements, so controlling the molecular packing could be a
memory devices, security printing, data-storage devices, optical promising strategy via chemical or physical alterations to tune
displays, and so forth.5,6
the solid state fluorescence properties.9 Moreover, modification
As is well known, conventional luminogens are normally of existing chromophores is an interesting and easy way to
highly emissive in dilute solutions while being weakly lumines- regulate the solid state emission, because of the known synthetic
cent or even totally quenched when aggregated, demonstrating pathway and expected photophysical characteristics. In recent
aggregation-caused quenching (ACQ) behavior, which limits years, positional isomers and polymorph dependent modu-
lated emissions have been wielded for various applications.10
Key Laboratory of Magnetic Molecules and Magnetic Information Material,
Ministry of Education, College of Chemistry and Material, Shanxi Normal University,
Linfen 041004, P. R. China. E-mail: jiajunhui@sxnu.edu.cn
† Electronic supplementary information (ESI) available: 1H and 13C NMR spectra,
HR-MS, absorption and emission spectra, and others. CCDC 1853608. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c8nj05933k
Therefore, further understanding the relationships between
fluorescence properties and molecular packing/conformation
of positional isomers could be more interesting and would be
key for future application of the designed fluorophores. More
and more extended conjugated systems, and donor–acceptor
(D–A) and donor–p–acceptor (D–p–A) chromophores have been
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019
New J. Chem.

View Article Online
Paper
NJC
Fig. 1 Images of o-TPEC, m-TPEC, and p-TPEC in THF solution (10ꢀ5 M,
Scheme 1 Synthetic routes of o-TPEC, m-TPEC, and p-TPEC.
top) and the solid state (bottom) under 365 nm light.
found to show optical properties via changing the position of
the substituents.10
However, their solids exhibited strong fluorescence under
365 nm light (Fig. 1). This result suggests that the three com-
pounds may be AIE molecules. This is further proved by a solvent–
nonsolvent fluorescence test. o-TPEC, m-TPEC, and p-TPEC are
highly soluble in THF, but insoluble in water. Using THF/water
as a mixed solvent and increasing the water fraction would cause
these molecules to aggregate and change their emission spectra.
As shown in Fig. 2, the fluorescence peak intensities of p-TPEC
are gradually intensified with the growing water fraction. It was
understandable that a new emission peak (shoulder) appeared at
about 500 nm for p-TPEC in THF/H2O with fw Z 20% with the
emission intensities gradually intensified. And when the water
fraction was at 90%, the fluorescence intensity of the mixture
solution reached the maximum with about 3.5-fold enhance-
ment higher than that in THF ( fw = 0%). The fluorescence
intensity increased significantly with the water fraction below
50% for compound o-TPEC. However, when the water fraction
was at 60%, the fluorescence intensity of the mixture solution
reached the maximum with a 2.82-fold enhancement higher
than that in pure THF. However the FL intensity decreased with
the water fraction over 60%, and when the water fraction was
80%, the fluorescence intensity was near to that of the THF
solution. The fluorescence behavior of m-TPEC in THF/H2O
solution was similar to that of o-TPEC (Fig. S2, ESI†). The strong
emission of o-TPEC ( fw = 0.5), m-TPEC ( fw = 0.6) and p-TPEC
( fw = 0.9) can be attributed to the formation of aggregates. The
aggregate formation was confirmed by field emission scanning
electron microscopy (FESEM) measurements (Fig. S3, ESI†). The
UV-vis absorption spectra of o-TPEC, m-TPEC, and p-TPEC were
obtained in THF/water mixtures (Fig. S4, ESI†), and a level-off
tail started to appear in the longer wavelength region when
the water content exceeded 50% (o-TPEC), 40% (m-TPEC) and
Above all, deciphering the structure–property relationships
of AIE luminogens is crucial to further molecular design and
understand the mechanism of operation. In this contribution,
we designed and synthesized three TPE-decorated benzaldehyde
isomers in high yields (Scheme 1) aiming to indicate the effect
of the substitution position on MFC. Then, we investigated the
aggregation-induced emission (AIE) properties in THF–H2O mix-
tures and reversible mechanochromic luminescent properties by
grinding with a mortar and pestle and fuming with dichloro-
methane (DCM). Interestingly, the three isomers showed differ-
ent MFC properties. X-ray structural analysis, XRD, DSC and
theoretical studies were performed to gain more insight on the
fluorescence switching mechanism. These studies suggest that
the switching of fluorescence was due to the change from the
crystalline phase with a twisted molecular structure to a more
planar amorphous phase.
Results and discussion
The target compounds were prepared in moderate to high
yields (78–85%) by Suzuki–Miyaura cross-coupling reactions cata-
lyzed by the palladium(0) complex, as illustrated in Scheme 1.
Briefly, p-TPEC was obtained by the coupling between (2-(4-
bromophenyl)ethene-1,1,2-triyl)tribenzene and (4-formylphenyl)-
boronic acid, while the other compounds were prepared by the
coupling between (2-(4-bromophenyl)ethene-1,1,2-triyl)tribenzene
and the corresponding boronic acids. The resulting compounds
were characterized by NMR spectroscopy and elemental analysis,
with satisfactory results being obtained.
Aggregation induced emission investigation
The absorption and fluorescence spectra of the three isomers in
THF (10ꢀ5 M) are given in Fig. S1 (ESI†). The absorption peaks/
shoulders at 247/300/325, 247/324, and 247/295/342 nm are
recorded for o-TPEC, m-TPEC, and p-TPEC, respectively. The last
band is assignable to the intramolecular charge transfer (ICT)
transition. And the fluorescence emission peaks are measured at
424, 408, and 483 nm for o-TPEC, m-TPEC, and p-TPEC, respec-
tively. These results indicate that p-TPEC has the largest conjuga-
tion among the three isomers.
Upon UV irradiation, the THF solutions of the three isomers
are weakly or even nonemissive, which should be ascribed to
Fig. 2 Fluorescence spectra of p-TPEC in the mixtures of THF and water
with different volume ratios (a); the plots of the intensities vs. water content (b);
the highly active energy consuming intramolecular motions. the inset is the corresponding images of p-TPEC under 365 nm light.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019

View Article Online
NJC
Paper
50% (p-TPEC), respectively, confirming the formation of aggre-
gates.11 To quantitatively estimate the emission properties, the
PL efficiencies of the luminogens in THF solution (Ff,s) and as-
prepared solid (Ff,solid) states were determined. The Ff,s values
are as low as 0.61%, 0.86%, and 0.78% for o-TPEC, m-TPEC, and
p-TPEC, and their Ff,solid values are boosted to 8.8%, 24.4%, and
22.8%, yielding AIE factors (aAIE = Ff,solid/Ff,s) of 14.4, 28.4,
and 29.3, respectively.6c The relatively low Ff,solid of o-TPEC
might be ascribed to its more active molecular motions in the
solid state.9b As mentioned above, the three isomers should be
AIE molecules.
Fig. 4 Photos of o-TPEC, m-TPEC and p-TPEC color changes under grinding
and fuming or heating stimuli conditions using a 365 nm UV lamp.
Electrochemical properties and density functional theory
calculations
Table 1 Electronic spectral data of o-TPEC, m-TPEC, and p-TPEC cal-
To more deeply study the three AIE molecules at the molecular
level, quantum mechanical computations were carried out to
obtain the optimized geometry of the compounds. The lowest
energy spatial conformations were calculated using Gaussian
09W software. Fig. 4 shows the highest occupied molecular
orbitals (HOMOs) and the lowest unoccupied molecular orbit-
als (LUMOs) of o-TPEC, m-TPEC, and p-TPEC after structural
optimization by the density functional method at the B3LYP/6-
31G(d,p) level. The optimized geometries show twisted confor-
mations with different dihedral angles of the TPE group and
the adjacent phenyl group, which are calculated to be 130.751,
34.921 and 34.631 (Fig. S5, ESI†), respectively, which indicated
that they are non-planar molecules. Interestingly, obvious migra-
tions of electron clouds are discovered from the TPE groups to
the formyl groups, and little difference in the migration of the
electron clouds among these compounds was found (Fig. 3).
As little difference in the migration of the electron clouds
was found, we further carried out quantitative analysis of the
electronic spectral data to explore the divergence between the
dipole moment and the energy gap. As shown in Table 1, time-
dependent density functional theory (TD-DFT) calculations
were carried out, and the dipole moments of the compounds
were determined to be 3.78, 3.63, and 4.83 Debye for o-TPEC,
m-TPEC, and p-TPEC respectively, which indicated that p-TPEC
had the largest molecular polarity. The calculated energy gaps
according to the difference in the HOMO and the LUMO for
o-TPEC, m-TPEC, and p-TPEC were 3.61, 3.51 and 3.44 eV,
culated with TD-DFT at the B3LYP/6-31 G level
mb
(debye) (eV)
HOMO LUMO HOMOc E1
E2
d
e
Compound f a
(eV)
(eV)
(eV) (eV)
o-TPEC
m-TPEC
p-TPEC
0.1265 3.78
0.0289 3.63
0.3977 4.83
ꢀ5.44
ꢀ1.83 ꢀ5.01
ꢀ1.87 ꢀ5.05
ꢀ2.02 ꢀ5.09
3.61 3.15
3.51 3.24
3.44 3.14
ꢀ5.38
ꢀ5.46
a
b
c
Oscillator strength. Dipole moment. Obtained using the onset
d
oxidation potentials from CV curves. Energy gaps calculated from
quantum chemical analysis. Energy gaps calculated from UV-vis
e
absorption spectra.
respectively. The energy levels of the HOMOs were also obtained
using the onset oxidation potentials from the CV curves (Fig. S6,
ESI†), and were consistent with the result of quantum chemical
computations. At the same time, the energy gaps calculated from
the UV-vis absorption spectra for o-TPEC, m-TPEC, and p-TPEC
were about 3.15, 3.24, and 3.14 eV, respectively. Moreover, the
stimulated absorption spectrum showed strong absorption bands
with maxima of ca. 392.4 nm, 393.3 nm and 399.9 nm because of
the transition from the HOMO to the LUMO (Fig. S7–S9 and
Tables S1–S3, ESI†).
Mechanofluorochromism (MFC)
As is well known, some AIE materials with a twisted structure
possess MFC properties. From the DFT analysis of o-TPEC,
m-TPEC, and p-TPEC, the structures possessed big torsions.
Thus, to check whether the three isomers possess MFC proper-
ties, a small amount of the pristine powers was ground using
vegetable parchments, and under UV irradiation a greenish-
yellow letter ‘‘T’’, yellowish-green letter ‘‘P’’, and bright-yellow
letter ‘‘E’’ were seen clearly on the ‘‘paper’’ in the written area for
o-TPEC, m-TPEC, and p-TPEC, and their emitting colors changed
into blue-green, bright blue, and cyan light upon fuming by
DCM for about 30 s (for o-TPEC) or 90 s (for m-TPEC and
p-TPEC). Moreover, the fluorescence color could also be restored
to that of the pristine material by heating the ground powder for
10 min at 110 1C (Fig. 4). In order to gain further information, the
emission spectra of o-TPEC, m-TPEC, and p-TPEC in solid states
were investigated. As shown in Fig. 5, the as-prepared solids of
o-TPEC, m-TPEC, and p-TPEC showed emission peaks/shoulders
at 488/498, 470, and 483 nm, respectively, whereas their ground
Fig. 3 Highest occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) of o-TPEC, m-TPEC, and p-TPEC.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019
New J. Chem.

View Article Online
Paper
NJC
Fig. 6 Powder wide-angle X-ray diffraction patterns of o-TPEC, m-TPEC,
and p-TPEC in different states at room temperature.
Fig. 5 Normalized PL spectra of o-TPEC (lex = 420 nm), m-TPEC (lex
=
400 nm), and p-TPEC (lex = 425 nm) in different solid-states: pristine,
grinding, heating and fuming.
amorphous solids exhibit greenish yellow or yellow emissions
with maxima at about 506, 515, and 522 nm. The grinding-
induced spectral shifts for o-TPEC, m-TPEC, and p-TPEC were
about 8 nm, 45 nm, and 39 nm. And the MFC activities of the
three compounds increased with the sequence of m-TPEC 4
p-TPEC 4 o-TPEC. The solid fluorescence efficiencies (F) of the
ground o-TPEC, m-TPEC, and p-TPEC solids are 9.3%, 21.2%,
and 20.4%, respectively, which are lower than those of the
crystalline states except for o-TPEC. After being fumed with
dichloromethane (DCM) solvent, the emissions of the ground
solids can be restored to their original states, thus suggesting
the reversibility of the mechanochromism. Moreover, this
reversible change of emissive color can be repeated many times
without fatigue under alternating grinding and solvent fuming
procedures (Fig. S10, ESI†).
Fig. 7 DSC curves of o-TPEC, m-TPEC, and p-TPEC under pristine and
ground states.
pristine and ground samples showed that new exothermal
re-crystallization peaks were observed at 102.7 1C, 93.8 1C, and
98.2 1C for ground o-TPEC, m-TPEC, and p-TPEC samples,
respectively (Fig. 7). These results indicated that at the above-
mentioned temperatures, thermal re-crystallization begins for
these ground amorphous powders, and it can be concluded that
the crystals of pristine samples were destroyed and converted to
the amorphous state by the grinding treatment.5,9
Fortunately, we are able to obtain a single crystal of o-TPEC
suitable for crystal structure analysis, and the single crystal
X-ray structure of o-TPEC provides more insight into the mechano-
chromic behaviors. As shown in Fig. 8 o-TPEC adopts twisted
conformations, one o-TPEC molecule has three intermolecular
In most cases, the mechanism of the MFC behavior results
from the change of molecular packing modes upon external
force. To deeply understand what happens upon pressing the
three isomers, powder wide-angle X-ray diffraction (XRD) and
differential scanning calorimetry (DSC) experiments were con-
ducted using the original, ground, and fumed samples. As
shown in Fig. 6, the sharp scattering and intense peaks in the
original solids suggested well-ordered microcrystalline struc-
tures. In contrast, the diffraction patterns of the ground samples
showed decreased or even no diffraction peaks, indicating that
the microcrystalline structure was destroyed and transformed
to an amorphous structure.12,13 As expected, the fumed samples
led to the regeneration of well-ordered microcrystalline struc-
tures accompanying the reappearance of sharp scattering peaks,
which was consistent with the original samples and implied the
restoration of the original regular crystalline molecular packing.
The results indicated that the phase transition between the
crystalline and amorphous states would cause MFC behaviours.
It is also noteworthy that, the crystalline fluorescence emission is
blue-shifted compared to its amorphous one, which indicated
that the molecular conformation is more twisted in the crystal-
Fig. 8 Molecular packing of o-TPEC in single crystals with C–HꢁꢁꢁO (2.70 Å)
line than amorphous states.9b In addition, DSC thermograms of and C–Hꢁ ꢁꢁp (2.88, 2.90 Å).
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019

View Article Online
NJC
Paper
weak interactions with four other molecules, including 0.0261 sꢀ1 in the 2y range from 5 to 50. Differential scanning
C–Hꢁ ꢁ ꢁO (2.70 Å) and C–Hꢁ ꢁ ꢁp (2.88 Å and 2.90 Å). Such twisted calorimetry (DSC) curves were obtained using a DSC 200 F3 at
conformations not only facilitate intramolecular motions in a heating rate of 10 1C minꢀ1, and the data of all samples
solution, which can effectively consume the exciton energies, (pristine and ground) were collected when they were heated for
thus making it poorly emissive, but also suppress the p–p the first time. FESEM was performed using a JSM-7500F. The
staking of the molecules in crystals. Meanwhile, intermolecular molecular configuration was used to obtain the frontier orbitals
interactions firmly rigidify the molecular conformations, thus of o-TPEC, m-TPEC, and p-TPEC by density functional theory
diminishing nonradiative deactivation of the excitons. Moreover, (DFT) calculations at the B3LYP/6-31G(d,p) level with the
such twisted conformations in crystals are easy to planarize Gaussian 09W program package. The single-crystal X-ray dif-
upon grinding, thus generating red-shifted emission.9b
fraction data of the o-TPEC crystal were collected using a Bruker
D8 Venture diffractometer. The CCDC number of o-TPEC is
1853608.
Conclusions
Synthesis
Three TPE decorated benzaldehyde isomers were designed and
synthesized via the Suzuki–Miyaura coupling reaction with
higher yields. Interestingly, the three isomers are all aggrega-
tion induced emission (AIE) and MFC dyes. The solid emission
studies showed that their fluorescence color could change
reversibly between blue-green, (488/498 nm), bright blue
(470 nm), and cyan (483 nm), and greenish-yellow (506 nm),
yellowish-green (515 nm), and bright-yellow (522 nm) through
grinding and dichloromethane (DCM) fuming treatment, giving
large spectral red-shifts of 8, 45, and 39 nm, respectively. And
the MFC activities of the three compounds are increased with
the sequence of m-TPEC (45 nm) 4 p-TPEC (39 nm) 4 o-TPEC
(8 nm). X-ray structural analysis, XRD, DSC and theoretical
studies suggest that the change from the crystalline phase with
a twisted molecular structure to a more planar amorphous
phase should be responsible for the MFC properties. These
results suggest the potential applications of these luminogens
as smart mechanochromic materials.
40-(1,2,2-Triphenylvinyl)-[1,10-biphenyl]-2-carbaldehyde (o-TPEC).
Under an atmosphere of nitrogen, to a mixture of compound
(2-(4-bromophenyl)ethene-1,1,2-triyl)tribenzene (411 mg, 1.0 mmol),
2-(dihydroxyboryl)benzaldehyde (225 mg, 1.5 mmol) and Pd(PPh3)4
(0.05 eq.) in 10 mL toluene/H2O (1:1) was added K2CO3 (345 mg,
2.5 mmol), and the reaction solution was refluxed overnight.
The reaction mixture was cooled to room temperature and then
poured into 500 mL water, extracted with CH2Cl2 and dried over
anhydrous MgSO4. The crude product was purified by column
chromatography on silica gel (petroleum ether/DCM = 2/1) to
yield o-TPEC as a white solid (349 mg, 80%). m.p.: 185–186 1C.
IR (KBr, cmꢀ1): 758, 831, 1026, 1333, 1443, 1576, 2366, 2848,
1
3023, 3059, 3078. H NMR (600 MHz, CDCl3) d = 9.89 (s, 1H),
7.99 (d, J = 7.8 Hz, 1H), 7.60 (t, J = 7.5 Hz, 1H), 7.46 (t, J = 7.6 Hz,
1H), 7.41 (d, J = 7.7 Hz, 1H), 7.15–7.11 (m, 13H), 7.10–7.07 (m,
3H), 7.07–7.04 (m, 3H) (Fig. S11, ESI†). 13C NMR (151 MHz,
CDCl3) d = 192.54, 145.83, 143.85, 143.51, 143.44, 143.35,
141.83, 140.16, 135.56, 133.66, 133.50, 131.35, 131.30, 130.63,
129.48, 127.81, 127.74, 127.70, 127.64, 127.48, 126.75, 126.65,
126.61 (Fig. S12, ESI†). HR-MS: m/z 459.1713, [M + Na]+
(Fig. S13, ESI,† calcd for C33H24ONa: 459.1719); anal. calcd (%)
for C33H24O: C, 90.79; H, 5.54; N, 3.67. Found (%): C, 90.75;
Experimental section
Measurements and instruments
All the raw materials were used without further purification. All H, 5.55; N, 3.69.
the solvents were purchased from Beijing Chemical Works
40-(1,2,2-Triphenylvinyl)-[1,10-biphenyl]-3-carbaldehyde (m-TPEC).
(Beijing, China) and were of analytical reagent grade; moreover, The synthetic method for compound m-TPEC was similar to
1
they were used without further purification. The H NMR and that of compound o-TPEC. It was purified by column chromato-
13C NMR spectra were recorded using a Mercury Plus instru- graphy (silica gel, petroleum ether/CH2Cl2 = 1/1) to afford a
ment at 600 MHz and 151 MHz by using CDCl3 as the solvent in white solid (78% in yield). m.p.: 150–152 1C. IR (KBr, cmꢀ1):
all cases. The HR-MS spectra were recorded using a Bruker 766, 832, 1027, 1361, 1441, 1583, 1732, 2355, 2733, 3030, 3055,
Impact II. The UV-vis absorption spectra were obtained using a 3078. 1H NMR (600 MHz, CDCl3) d = 10.06 (s, 1H), 8.05 (s, 1H),
VARIAN Cary 5000 spectrophotometer. The absorption spectra 7.81 (d, J = 7.7 Hz, 2H), 7.56 (t, J = 7.6 Hz, 1H), 7.38 (d, J = 8.3Hz,
of the solids were obtained by measuring their films on the 2H), 7.14–7.09 (m, 11H), 7.09–7.06 (m, 4H), 7.05–7.03 (m, 2H)
surface of a silica plate. Photoluminescence measurements (Fig. S14, ESI†). 13C NMR (151 MHz, CDCl3) 13C NMR (151 MHz,
were obtained using a Cary Eclipse fluorescence spectrophoto- CDCl3) d = 192.38, 143.66, 143.62, 143.61, 143.57, 141.69,
meter. The fluorescence quantum yields of TPE-based deriva- 141.51, 140.25, 137.35, 136.87, 132.80, 132.01, 131.39, 131.34,
tives in solvents were measured by comparing with a standard 131.33, 129.42, 129.02, 128.51, 127.98, 127.82, 127.76, 127.68,
(quinine in 0.1 N H2SO4, FF = 0.546) and the excitation 126.63, 126.58, 126.53, 126.27 (Fig. S15, ESI†). HR-MS: m/z
wavelength was 365 nm. C, H, and N elemental analyses were 459.1705, [M + Na]+ (Fig. S16, ESI,† calcd for C33H24ONa:
performed using a vario MACRO cube elemental analyzer. The 459.1719); anal. calcd (%) for C33H24O: C, 90.79; H, 5.54; N,
XRD patterns were obtained using an Empyrean X-ray diffraction 3.67. Found (%): C, 90.75; H, 5.52; N, 3.69.
instrument equipped with graphite-monochromatized Cu Ka
radiation (l = 1.5418 Å) by employing a scanning rate of The synthetic method for compound p-TPEC was similar to
40-(1,2,2-Triphenylvinyl)-[1,10-biphenyl]-4-carbaldehyde (p-TPEC).
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019
New J. Chem.

View Article Online
Paper
NJC
5 (a) Y. Sagara and T. Kato, Nat. Chem., 2009, 1, 605–610;
(b) Z. Mao, Z. Y. Yang, Y. X. Mu, Y. Zhang, Y. F. Wang,
Z. G. Chi, C. C. Lo, S. W. Liu, A. Lien and J. R. Xu,
Angew. Chem., Int. Ed., 2015, 54, 6270–6273; (c) J. H. Jia
and Y. Y. Wu, Dyes Pigm., 2017, 147, 537–543; (d) T. Jadhav,
J. M. Choi, B. Dhokale, S. M. Mobin, J. Y. Lee and
R. Misra, J. Phys. Chem. C, 2016, 120, 18487–18495;
(e) C. D. Dou, L. Han, S. S. Zhao, H. Y. Zhang and
Y. Wang, J. Phys. Chem. Lett., 2011, 2, 666–670; ( f ) P. Wen,
Z. X. Gao, R. Zhang, A. R. Li, F. Zhang, J. Li, J. J.
Xie, Y. Z. Wu, M. Wu and K. P. Guo, J. Mater. Chem. C,
2017, 5, 6136–6143; (g) P. C. Xue, P. Chen, J. H. Jia,
Q. X. Xu, J. B. Sun and B. Q. Yao, Chem. Commun., 2014,
50, 2569–2571.
that of compound o-TPEC. It was purified by column chromato-
graphy (silica gel, petroleum ether/CH2Cl2 = 1/1) to give a white
solid (85% in yield). m.p.: 196–198 1C. IR (KBr, cmꢀ1): 765, 821,
1025, 1308, 1444, 1696, 1726, 2343, 2725, 2821, 3030, 3056,
1
3075. H NMR (600 MHz, CDCl3) d = 10.03 (s, 1H), 7.91 (d, J =
8.3 Hz, 2H), 7.71 (d, J = 8.2 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.14–
7.10 (m, 11H), 7.09–7.05 (m, 4H), 7.05–7.02 (m, 2H) (Fig. S17,
ESI†). 13C NMR (151 MHz, CDCl3) d = 191.92, 146.69, 144.22,
143.56, 143.51, 141.68, 140.17, 137.29, 135.05, 132.03, 131.39,
131.34, 131.31, 130.23, 127.83, 127.78, 127.68, 127.37, 126.66,
126.61, 126.57, 126.53 (Fig. S18, ESI†). HR-MS: m/z 459.1703,
[M + Na]+ (Fig. S19, ESI,† calcd for C33H24ONa: 459.1719); anal.
calcd (%) for C33H24O: C, 90.79; H, 5.54; N, 3.67. Found (%): C,
90.75; H, 5.54; N, 3.69.
6 (a) Z. G. Chi, X. Q. Zhang, B. J. Xu, X. Zhou, C. Q. Ma,
Y. Zhang, S. W. Liu and J. R. Xu, Chem. Soc. Rev., 2012,
41, 3878–3896; (b) P. C. Xue, J. P. Ding, P. P. Wang and
R. Lu, J. Mater. Chem. C, 2016, 4, 6688–6706; (c) J. H. Jia,
P. C. Xue and R. Lu, Tetrahedron Lett., 2016, 57, 2544–2548;
(d) J. H. Jia and H. J. Zhang, J. Photochem. Photobiol., A, 2018,
361, 112–116; (e) J. H. Jia and Y. Y. Wu, Dyes Pigm., 2017,
136, 657–662; ( f ) P. C. Xue, Z. C. Yang and P. Chen,
J. Mater. Chem. C, 2018, 6, 4994–5000; (g) A. Kishimura,
T. Yamashita, K. Yamaguchi and T. Aida, Nat. Mater.,
2005, 4, 546–549; (h) S. Yagai, T. Seki, H. Aonuma,
K. Kawaguchi, T. Karatsu, T. Okura, A. Sakon, H. Uekusa
and H. Ito, Chem. Mater., 2016, 28, 234–241; (i) P. C. Xue,
J. P. Ding, Y. B. Shen, H. Q. Gao and J. Y. Zhao, Dyes Pigm.,
2017, 145, 12–20.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
This work was financially supported by the National Natural
Science Foundation of China (21805175), the Natural Science
Foundation of Shanxi Province (201601D021056), and the
Scientific and Technological Innovation Foundation of Higher
Education of Shanxi Province (20161111).
Notes and references
7 J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu,
H. S. Kwok, X. Zhan, Y. Liu, D. Zhu and B. Z. Tang, Chem.
Commun., 2001, 1740–1741.
1 (a) L. Yao, S. T. Zhang, R. Wang, W. J. Li, F. Z. Shen,
B. Yang and Y. G. Ma, Angew. Chem., Int. Ed., 2014, 53,
2119–2123; (b) M. A. Baldo, M. E. Thompson and
S. R. Forrest, Nature, 2000, 403, 750–753; (c) J. Yang,
J. Huang, Q. Q. Li and Z. Li, J. Mater. Chem. C, 2016, 4,
2663–2684; (d) L. Ding, S. C. Dong, Z. Q. Jiang, H. Chen and
L. S. Liao, Adv. Funct. Mater., 2015, 25, 645–650;
(e) Y. J. Wang, Y. H. Zhu, G. H. Xie, H. M. Zhan,
C. L. Yang and Y. X. Cheng, J. Mater. Chem. C, 2017, 5,
10715–10720; ( f ) W. Z. Yuan, Y. G. Gong, S. M. Chen,
X. Y. Shen, J. W. Y. Lam, P. Lu, Y. W. Lu, Z. M. Wang,
R. R. Hu and N. Xie, et al., Chem. Mater., 2012, 24,
1518–1528.
8 (a) T. Butler, W. A. Morris, J. Samonina-Kosicka and C. L.
Fraser, Chem. Commun., 2015, 51, 3359–3362; (b) Q. Lu,
X. Li, J. Li, Z. Yang, B. Xu, Z. Chi, J. Xu and Y. Zhang,
J. Mater. Chem. C, 2015, 3, 1225–1234; (c) R. Misra,
T. Jadhav, B. Dhokale and S. M. Mobin, Chem. Commun.,
2014, 50, 9076–9078; (d) X. Zhang, Z. Chi, B. Xu, L. Jiang,
X. Zhou, Y. Zhang, S. Liu and J. Xu, Chem. Commun.,
2012, 48, 10895–10897; (e) S. Gundu, M. Kim, N. Mergu
and Y. A. Son, Dyes Pigm., 2017, 146, 7–13; ( f ) F. Han,
R. Zhang, Z. Zhang, J. Su and Z. Ni, RSC Adv., 2016, 6,
68178–68184.
2 (a) Q. Zhao, C. H. Huang and F. Y. Li, Chem. Soc. Rev.,
2011, 40, 2508–2524; (b) Y. M. Yang, Q. Zhao, W. Feng and
F. Y. Li, Chem. Rev., 2013, 113, 192–270; (c) Z. Q.
Guo, S. Park, J. Yoon and I. Shin, Chem. Soc. Rev., 2014,
43, 16–29.
9 (a) Y. X. Li, Z. Chen, Y. Cui, G. M. Xia and X. F. Yang, J. Phys.
Chem. C, 2012, 116, 6401–6408; (b) S. P. Pei, X. H. Chen,
Z. S. Zhou, H. Z. Zou. and Y. Y. Gong, Dyes Pigm., 2018, 154,
113–120; (c) V. S. Padalkar, K. Kuwada, D. Sakamaki,
N. Tohnai, T. Akutagawa, K. Sakai, T. Sakurai and S. Seki,
ChemistrySelect, 2017, 2, 1959–1966.
3 (a) J. Liang, B. Z. Tang and B. Liu, Chem. Soc. Rev., 2015, 44,
2798–2811; (b) J. F. Zhang, Y. Zhou, J. Yoon. and J. S. Kim, 10 (a) R. Wei, P. Song and A. Tong, J. Phys. Chem. C, 2013, 117,
Chem. Soc. Rev., 2011, 40, 3416–3429.
4 (a) P. Agarwala and D. Kabra, J. Mater. Chem. A, 2017, 5,
3467–3474; (b) G. B. Bodedla, K. R. Justin Thomas, M. S. Fan
and K. C. Ho, J. Org. Chem., 2016, 81, 640–653.
1348–1373; (b) J. H. Jia, K. Y. Cao, P. C. Xue, Y. Zhang, 11 (a) S. Mukherjee and P. Thilagar, Chem. Commun., 2013,
H. P. Zhou and R. Lu, Tetrahedron, 2012, 68, 3626–3632;
(c) J. H. Jia, Y. Zhang, P. C. Xue, P. Zhang, X. Zhao, B. J. Liu
and R. Lu, Dyes Pigm., 2013, 96, 407–413.
49, 7292–7294; (b) J. Mei, Y. Hong, J. W. Y. Lam,
A. Qin, Y. Tang and B. Z. Tang, Adv. Mater., 2014, 26,
5429–5479; (c) Y. Cao, M. Yang, Y. Wang, H. Zhou,
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019

View Article Online
NJC
Paper
J. Zheng, X. Zhang, J. Wu, Y. Tian and Z. Wu, J. Mater. 13 (a) B. Zhang, C. H. Hsu, Z. Q. Yu, S. Yang and E. Q.
Chem. C, 2014, 2, 3686–3694.
Chen, Chem. Commun., 2013, 49, 8872–8874; (b) T. Wen,
D. Zhang, J. Liu, R. Lin and J. Zhang, Chem. Commun.,
2013, 49, 5660–5662; (c) J. Wang, J. Mei, R. Hu, J. Z. Sun,
A. Qin and B. Z. Tang, J. Am. Chem. Soc., 2012, 134,
9956–9966.
12 (a) K. Mizuguchi and H. Nakano, Dyes Pigm., 2013, 96,
76–80; (b) T. Nishida, S. Ohta, F. Xu, K. Shinohara,
T. Kamada, H. Akashi, M. Takezaki, K. Wakamatsu and
A. Orita, Org. Lett., 2016, 18, 3988–3991.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019
New J. Chem.