Aggregation-induced emission properties of pyridyl-containing tetra-arylethenes

Article abstract of DOI:10.1002/bio.4023

Tetra-arylethene is one of the most important aggregation-induced emission (AIE) fluorophores. The electronic effect usually plays a vital role in their optical properties. However, the relationship between AIE property and electronic effect in the same fluorophore is rarely studied. Here, we designed and synthesized a series of pyridyl-containing tetra-arylethenes, whose electronic densities could be easily adjusted by the N-oxide or N-methylation of their pyridyl moieties. The optical data of these compounds at aggregation in different solvent systems or solid state exhibited obviously different AIE properties compared with the classic AIE-active tetraphenylethene (TPE).

Full text of DOI:10.1002/bio.4023

Received: 16 December 2020
DOI: 10.1002/bio.4023
Revised: 1 February 2021
Accepted: 1 February 2021
R E S E A R C H A R T I C L E
Aggregation-induced emission properties of pyridyl-containing
tetra-arylethenes
Shuwei Zhang
| Dong Li | Xinyao Wang | Jie Fan | Ting Wang |
Shangkui Yu | Wenyi Liao | Xiaodong Jia | Yu Yuan
School of Chemistry and Chemical
Abstract
Engineering, Yangzhou University, Yangzhou,
China
Tetra-arylethene is one of the most important aggregation-induced emission (AIE)
fluorophores. The electronic effect usually plays a vital role in their optical properties.
However, the relationship between AIE property and electronic effect in the same
fluorophore is rarely studied. Here, we designed and synthesized a series of pyridyl-
containing tetra-arylethenes, whose electronic densities could be easily adjusted by
the N-oxide or N-methylation of their pyridyl moieties. The optical data of these
compounds at aggregation in different solvent systems or solid state exhibited
obviously different AIE properties compared with the classic AIE-active
tetraphenylethene (TPE).
Correspondence
Shuwei Zhang, School of Chemistry and
Chemical Engineering, Yangzhou University,
Yangzhou, 225002, China.
Email: shuweiz@yzu.edu.cn
Funding information
Priority Academic Program Development of
Jiangsu Higher Education Institutions;
Yangzhou University Research Startup Fund;
National Natural Science Foundation of China,
Grant/Award Number: 21702180
1
|
INTRODUCTION
deficient, or by N-oxide to make it electron-rich, which could be used
to study the influence of electronic effect on AIE properties of
Organic fluorescent molecules whose optical properties can be conve-
niently tuned by adjusting molecular structures or physical states have
been attracting great attention in fields of biological imaging, chemical
sensing and optoelectronic systems etc.[1–6] Among these molecules,
aggregation-induced emission (AIE) fluorophores exhibited strong
emission in aggregation and solid state, which well overcame the defi-
ciency in aggregation-induced quenching (ACQ) that often happens in
traditional luminescent materials.[7,8] Over the past two decades,
many AIE-active fluorophores have been prepared and applied in vari-
ous fields due to their excellent optical properties in aggregation.[9–15]
As one type of representative AIE-active fluorophore, tetra-
arylethene derivatives such as tetraphenylethene, tetrathienylethene,
tetrafurylethene have been studied.[16–22]
fluorophores with the same emissive core.
Here, we designed and synthesized a series of pyridyl-containing
tetra-arylethenes whose molecular electronic properties could be easily
adjusted by N-oxide or N-methylation. The formation of salts resulted
in a stronger intramolecular charge transfer (ICT) that led to poor AIE
properties in more polar mixed solvents system such as the THF/water
system. When the solvents were changed to DCM/hexane, the com-
pounds and their N-oxides displayed AIE properties. In this way, we
could study the relationship between AIE properties and electronic
effects in the same fluorophore (Scheme 1).
2
|
EXPERIMENTAL
As well known, the electronic characteristic of organic fluorescent
molecules greatly affects their optical properties.[23–27] Many organic
AIE-active fluorophores have been employed to study the relationship
between electronic effects and AIE properties, however these mole-
cules usually have obvious distinct molecular structures.[28–32] The
AIE properties of fluorophores with the same emissive core and obvi-
ously different electronic effects are rarely studied. Pyridine is one
class of electron-withdrawing aryl ring, and exists widely in nature and
other functional compounds.[33–38] Electronic characteristics of pyri-
dine can be easily adjusted by N-methylation to make it more electron
2.1
|
Materials and apparatus
Unless otherwise stated, all the solvents and regents were of analyti-
cal grade and used directly without further purification after purchase
from commercial suppliers. NMR spectra were measured on an
Agilent 400-MR DD2 NMR spectrometer and reported as parts per
million (ppm) from the internal standard TMS. High-resolution mass
spectrometry (HRMS) data were collected on a Bruker Dalton maXis
mass spectrometer. Mass spectra (MS) were obtained using a Bruker
958
© 2021 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/bio
Luminescence. 2021;36:958–963.

ZHANG ET AL.
959
stirred at 25ꢀC for 2 h, then the mixture was concentrated under
reduced pressure to obtain the residue, which was purified by silica
column chromatography using petroleum ether/ethyl acetate (5/1 v/v)
to give 3Ph-Py-O as a yellow solid (0.36 g, 85.9%). 1H NMR
(400 MHz, CDCl3): δ 7.92–7.87 (m, 2H), 7.19 (dd, J = 5.0, 1.9 Hz, 3H),
7.17–7.12 (m, 3H), 7.11–7.03 (m, 5H), 7.03–6.95 (m, 4H), 6.87–6.83
(m, 2H); 13C NMR (101 MHz, CDCl3): δ 144.61, 143.41, 142.32,
142.17, 141.56, 138.42, 136.37, 131.21, 131.02, 128.50, 128.45,
128.41, 128.28, 128.15, 127.79, 127.40, 127.28; HRMS (ESI, m/z):
calc. For
C25H20NO[M
+
H]+: 350.1539; found, 350.1551
(Figures S17 and S18).
2.2.3
|
Synthesis of compound 3Ph-Py-Me
Compound 3Ph-Py (0.50 g, 1.50 mmol) was dissolved in 10 ml
acetonitrile, followed by the addition of iodomethane (0.43 g,
3.0 mmol), then the mixture was refluxed for 16 h. After cooling
to room temperature, the mixture was concentrated under reduced
pressure to produce the residue, which was purified by silica
column chromatography to obtain 3Ph-Py-Me as a yellow solid
SCHEME 1 Molecular structures of pyridyl-containing tetra-
arylethenes
(0.61 mg, 85.5%). 1H NMR (400 MHz, CDCl3):
δ 8.89–8.83
(m, 2H), 7.40–7.36 (m, 2H), 7.26 (d, J = 1.8 Hz, 2H), 7.24 (s, 1H),
AutoFlex matrix assisted laser desorption/ionisation (MALDI) time of
flight (TOF) mass spectrometer (MALDI-TOF-MS). UV–visible spectra
were measured on a UV-2550 ultraviolet spectrophotometer. Fluores-
cence spectra were obtained on an F-4500 spectrofluorometer
(Figure S14).
7.20–7.00 (m, 8H), 7.00–6.92 (m, 4H), 4.48 (d, J = 2.1 Hz, 3H).
HRMS (ESI, m/z): calc. For
348.1759 (Figure S19).
C26H22N
[M]+: 348.1747; found,
2.2.4
|
Synthesis of compound 2Ph-2Py
2.2
|
Synthesis of the compounds
A mixture of phenyl(pyridin-4-yl)methanone (2.00 g, 10.9 mmol)
and zinc dust (2.14 g, 32.8 mmol) was dissolved in 40 ml of anhy-
drous THF under a nitrogen atmosphere. Then TiCl4 (7.20 ml,
65.5 mmol) was slowly added under stirring in an ice bath. After-
wards the reaction mixture was slowly warmed to room tempera-
ture, and then refluxed overnight. After cooling to room
temperature, a saturated K2CO3 aqueous solution was added. The
resulting mixture was extracted with ethyl acetate, and the
combined organic layer was washed further with brine, and dried
over Na2SO4. The solvent was then removed under reduced
pressure to produce the intermediate that was mixed with
trimethylorthoformate (1.42 ml, 5.46 mmol) and benzoic acid
(0.67 g, 5.46 mmol). The mixture was stirred at 180ꢀC for 2 h.
After cooling to room temperature, 20 ml dichloromethane was
added, and the solution was washed with saturated Na2CO3, and
dried with anhydrous Na2SO4. The solvent was removed under
reduced pressure to produce the crude product, which was purified
by silica column chromatography using petroleum ether/ethyl ace-
tate (10/1 v/v) as eluent to give 2Ph-2Py as a yellow solid (0.36 g,
2.2.1
|
Synthesis of compound 3Ph-Py
(2-Bromoethene-1,1,2-triyl)tribenzene (0.50 g, 1.49 mmol), Na2CO3
(0.79 g, 7.45 mmol), Pd(OAc)2 (33.5 mg, 0.15 mmol), PPh3 (0.78 g,
2.98 mmol) and 4-pyridylboronic acid (0.92 g, 7.45 mmol) were dis-
solved in 30 ml of dioxane/water (4/1 v/v). The reaction mixture was
refluxed under a nitrogen atmosphere overnight. After cooling to
room temperature, the reaction mixture was extracted with ethyl ace-
tate and dried over anhydrous Na2SO4. After removal of the solvent
under reduced pressure, the crude product was purified using silica
column chromatography with petroleum ether/ethyl acetate (10/1 v/v)
as the eluent to produce 3Ph-Py as a slightly yellow solid (0.45 g,
91.2%). 1H NMR (400 MHz, CDCl3): δ 8.35–8.28 (m, 2H), 7.16–6.89
(m, 17H). HRMS (ESI, m/z): calc. For C25H20N [M + H]+: 334.1596;
found, 334.1587 (Figure S16).
2.2.2
|
Synthesis of compound 3Ph-Py-O
85.9%). 1H NMR (400 MHz, CDCl3):
δ 8.82–8.74 (m, 4H),
7.82–7.73 (m, 4H), 7.64–7.57 (m, 2H), 7.54 (dd, J = 4.4, 1.5 Hz,
4H), 7.48 (t, J = 7.8 Hz, 4H). HRMS (ESI, m/z): calc. For C24H19N2
[M + H]+: 335.1548; found, 335.1559 (Figure S20).
A mixture of 3Ph-Py (0.40 g, 1.20 mmol) and m-CPBA (0.31 g,
1.80 mmol) were dissolved in 8 ml dichloromethane. The reaction was

960
ZHANG ET AL.
2.2.5
|
Synthesis of compound Ph-3Py
2 ml THF/H2O and DCM/hexane mixed solvents to give sample
solutions at the concentration of 10 μM, water and hexane fractions
of the mixed solvents were from 0 to 90%. The optical measurements
were taken a2 h later.
The synthesis procedure for 3Ph-Py was same as that for Ph-3Py. 1
H
NMR (400 MHz, CDCl3): δ 8.42–8.37 (m, 6H), 7.23–7.15 (m, 3H), 6.96
(d, J = 7.5 Hz, 2H), 6.92–6.89 (m, 4H), 6.87 (d, J = 4.8 Hz, 2H). HRMS
(ESI, m/z): calc. For C23H18N3 [M + H]+: 336.1501; found, 336.1512
(Figure S25).
3
|
RESULTS AND DISCUSSION
3.1
|
Synthesis of the pyridyl-containing tetra-
2.2.6
|
Synthesis of compounds 2Ph-2Py-O and
arylethenes
Ph-3Py-O
The synthesis routes of these pyridyl-containing compounds are
shown in Scheme S1. Compounds 3Ph-Py and Ph-3Py were synthe-
sized using the Suzuki coupling reaction, followed by N-oxide and
N-methylation to give compounds 3Ph-Py-O, 3Ph-Py-Me, Ph-3Py-O
and Ph-3Py-Me. Compound 2Ph-2Py was produced using the
McMurray coupling reaction. Compounds 2Ph-2Py-Me and 2Ph-2Py-O
were obtained by N-oxide and N-methylation of 2Ph-2Py. All
compounds were characterized by NMR and HRMS. The detailed
procedures and characterizations are described in the Supporting
information.
The synthesis procedures for compounds 2Ph-2Py-O and Ph-3Py-O
were same as for 3Ph-Py-O. Compound 2Ph-2Py-O: 1H NMR
(400 MHz, CDCl3): δ 8.24 (d, J = 7.2 Hz, 4H), 7.77–7.67 (m, 8H),
7.66–7.59 (m, 2H), 7.51 (t, J = 7.6 Hz, 4H); 13C NMR (101 MHz,
CDCl3): δ 139.27, 135.93, 133.25, 133.02, 129.54, 128.71, 126.88;
HRMS (ESI, m/z): calc. For C24H19N2O2 [M + H]+: 367.1441; found,
367.1452.
Compound Ph-3Py-O: 1H NMR (400 MHz, CDCl3): δ 8.06 (d,
J = 7.2 Hz, 2H), 8.00 (d, J = 7.3 Hz, 2H), 7.94 (d, J = 7.3 Hz, 2H),
7.32–7.26 (m, 2H), 7.24 (s, 1H), 7.02–6.92 (m, 4H), 6.89 (d, J = 7.3 Hz,
2H), 6.82 (d, J = 7.3 Hz, 2H); 13C NMR (101 MHz, CD3OD): δ 144.54,
143.44, 143.21, 142.34, 141.05, 140.64, 140.36, 140.13, 136.84,
132.23, 130.44, 130.31, 130.29, 130.12, 130.10; HRMS (ESI, m/z):
3.2
|
Optical properties
calc. For
C
23H18N3O3 [M
+
H]+: 384.1343; found, 384.1352
After we obtained the pyridyl-containing tetra-arylethenes, their
absorption and emission behaviours were investigated in two widely
used good/bad mixed solvents, THF/water and dichloromethane/hex-
ane, at a fixed concentration (1.0 × 10−5 mol L−1). As shown in
Figures 1 and S1–S6, all these compounds had obvious absorption
peaks ascribed to the π–π* transitions of the conjugated structures.
Compounds 3Ph-Py and Ph-3Py and their derivatives exhibited three
absorption peaks ranging from 210 to 380 nm, while 2Ph-2Py and its
derivatives displayed two peaks in this region. When increasing the
number of pyridyl moieties in the molecular structures, the absorption
wavelengths shifted to shorter regions. N-methylations also induced a
blue shift compared with their precursor compounds and N-oxides
resulted in these compounds having longer absorption peaks.
Compared with the absorption in THF/water mixed solvents, those
compounds in less polar DCM/hexane mixed solvents displayed a red
shift in the absorbance maximums, which could due to the existence
of heteroatoms. When the amount of bad solvent was increased in
the mixed solvents, a decreased absorbance and spectral tails in the
long wavelength region were obvious, probably due to the formation
of aggregates; the observed blue shift indicated that an H-aggregate
should be formed in the mixed solvents.
(Figures S21, S22, S26 and S27).
2.2.7
Ph-3Py-Me
|
Synthesis of compounds 2Ph-2Py-Me and
The synthesis procedures for compounds 2Ph-2Py-Me and Ph-
3Py-Me were same as for 3Ph-Py-Me. Compound 2Ph-2Py-Me:
1H NMR (400 MHz, DMSO-d6): δ 9.17 (d, J = 6.5 Hz, 4H), 8.32 (d,
J = 6.5 Hz, 4H), 7.84–7.74 (m, 6H), 7.61 (t, J = 7.8 Hz, 4H), 4.41 (s,
6H); 13C NMR (101 MHz, DMSO-d6): δ 151.70, 146.93, 135.27,
134.62, 130.70, 129.55, 126.91, 48.68; HRMS (ESI, m/z): calc. For
C
26H24N2 [M]2+/2: 182.0964; found, 182.0971.
Compound Ph-3Py-Me: 1H NMR (400 MHz, CD3OD): δ 8.84 (t,
J = 6.6 Hz, 4H), 8.78–8.74 (m, 2H), 8.03–7.89 (m, 6H), 7.45–7.28 (m,
5H), 4.37–4.33 (m, 9H); 13C NMR (101 MHz, CD3OD): δ 156.95,
156.71, 155.21, 148.77, 147.83, 147.62, 147.03, 138.59, 136.57,
132.55, 131.72, 131.56, 131.49, 130.74, 130.59, 49.39, 48.95; HRMS
(ESI, m/z): calc. For C26H26N3 [M]3+/3: 126.7370; found, 126.7376
(Figures S23, S24, S28 and S29).
The fluorescent spectra of these tetra-arylethenes are shown in
Figures 2, 3 and S7–S13. Compound 3Ph-Py, 2Ph-2Py and Ph-3Py
exhibited the maximum peaks at 375, 310 and 305 nm in pure THF,
respectively, in which the emission intensity was much stronger than
that of TPE in THF. These emission intensities decreased when
increasing the water fraction (fw) in the mixed solvents. These results
indicated that substitution of pyridyl for phenyl in tetraphenylethene
2.3
|
Preparation of samples for optical
measurement
Stock solutions of the compounds were first prepared in THF (2 mM)
and DCM (2 mM), then 10 μl of stock solutions were transferred to

ZHANG ET AL.
961
FIGURE 1 UV–visible absorption spectra of (a) 3Ph-Py, (b) 3Ph-Py-O and (c) 3Ph-Py-me in THF/water mixed solvents with different fw.
Concentration: 1 × 10−5
M
FIGURE 2 Fluorescent spectra of (a) 3Ph-Py, (b) 3Ph-Py-O and (c) 3Ph-Py-me in THF/H2O mixed solvents with different fw; plot of I/I0
values versus fw (a1–c1), where I and I0 represent the emission intensities in THF/H2O mixed solvents and pure THF (a1–c1), respectively.
Concentration: 1 × 10−5
M
(TPE) distinctly changed the emission behaviours to ACQ. Similar
emission behaviours with longer wavelengths were detected for the
N-oxides at 400, 375 and 422 nm. However, the emission intensities
of N-methylations first increased, and then decreased with fw increase
in the mixed solvents. In these molecules, the introduction of
electron-withdrawing pyridyl moieties enabled the compounds to
undergo ICT that usually resulted in decreasing emission intensity and
a red shift, especially in the strongly polar protic solvents such as
water. Therefore, the different emission properties of these pyridyl-
containing compounds could be induced by competition between ICT
and aggregation.
Emission of these molecules in DCM/hexane mixed solvents
displayed similar characteristic peaks at longer wavelengths. However,
the pyridyl-containing compounds and their N-oxides showed AIE
properties, while the N-methylations still exhibited ACQ properties.
The emissive behaviours in DCM/hexane mixed solvents could have

962
ZHANG ET AL.
resulted from aggregation having more influence on emission than
ICT for the former two types of compounds, while ICT influenced the
N-methylations more. Next, we studied the luminescence properties
of these tetra-arylethenes in the solid state. When comparing the
fluorescent spectra of these compounds in mixed solvents, the
emission peaks of the solids were obviously red shifted. Compound
3Ph-Py had an obvious emission peak at 458 nm, and its N-oxide
exhibited a higher emission peak with a red shift of 10 nm. However,
the emission of its N-methylation was very poor. The three 2Ph-2Py
derivatives displayed very weak emission peaks in the region
400–500 nm. For Ph-3Py derivatives, compound Ph-3Py had a weak
emission peak at about 430 nm, and Ph-3Py-O had an obviously
increased emission peak at 530 nm, while Ph-3Py-Me was non-
emissive. The emission behaviours of these solids could be observed
directly from their luminescence images taken under a commercially
available UV lamp (Figures 4). These results demonstrated that the
emission behaviours of these compounds, especially their AIE
properties, can be tuned by changing the electronic effect.
FIGURE 3 Fluorescent spectra of (a) 3Ph-Py, (b) 3Ph-Py-O and (c) 3Ph-Py-me in DCM/hexane mixed solvents with different fh; plot of I/I0
values versus fh (A1-C1), where I and I0 represent the emission intensities in DCM/hexane mixed solvents and pure DCM (A1-C1), respectively.
Concentration: 1 × 10−5
M
FIGURE 4 Solid-phase luminescent spectra of the pyridyl-containing tetra-arylethenes. Inset: Photographs of solid-phase the pyridyl-
containing tetra-arylethenes under a 365 nm UV lamp

ZHANG ET AL.
963
[16] L. Viglianti, N. C. Leung, N. Xie, X. Gu, H. Sung, Q. Miao, D. Williams,
E. Licandro, B. Z. Tang, Chem. Sci. 2017, 8, 2629.
4
|
CONCLUSION
[17] C. Shen, Y. Wu, H. Zhang, E. Li, W. Zhang, X. Xu, W. Wu, H. Tian, W.
Zhu, Angew. Chem. Int. Ed. 2019, 58, 3784.
In conclusion, we designed and synthesized a series of pyridyl-
containing tetra-arylethenes, whose electronic densities could be
easily adjusted by the N-oxide or N-methylation of pyridyl moieties in
the same emissive cores. The obtained compounds exhibited obvious
distinct AIE properties compared with typical AIE-active TPE. The
introduction of pyridyl moieties could induce an ICT effect, and result
in the changed AIE behaviours of tetra-arylethenes. In this work, we
developed an easy way to study the relationship between the AIE
properties and electronic effects of tetra-arylethene using the same
fluorophore.
[18] L. Viglianti, N. Xie, H. Sung, A. Voityuk, N. C. Leung, Y. Tu, C. Baldoli,
I. Williams, R. K. Kwok, J. Y. Lam, E. Licandro, L. Blancafort, B. Z.
Tang, Angew. Chem. Int. Ed. 2020, 59, 8552.
[19] Y. Li, Y. Dong, L. Cheng, C. Qin, H. Nian, H. Zhang, Y. Yu, L. Cao,
J. Am. Chem. Soc. 2019, 141, 8412.
[20] M. Gabr, F. C. Pigge, RSC Adv. 2015, 5, 90226.
[21] J. Liu, J. Yang, J. Wang, Z. Chang, B. Li, W. Song, Z. Zhao, X. Lou, J.
Dai, F. Xia, Mater. Chem. Front. 2018, 2, 1126.
[22] J. Shen, D. Li, Y. Ruan, S. Xu, T. Yu, H. Zhang, Y. Jiang, Luminescence
2012, 27, 317.
[23] X. Zhang, H. Qi, Y. Liu, S. Yang, P. Li, Y. Qiao, P. Zhang, S. Wen, H.
Piao, K. Han, Chem. Sci. 2020, 11, 11205.
[24] S. Sarveswari, A. J. Beneto, A. Siva, Sens. Actuators B 2017, 245, 428.
[25] L. Xu, Q. Wang, Y. Zhang, Dyes Pigm. 2017, 136, 732.
[26] N. Hashimoto, R. Umano, Y. Ochi, K. Shimahara, J. Nakamura, S.
Mori, H. Ohta, Y. Watanabe, M. Hayashi, J. Am. Chem. Soc. 2018,
140, 2046.
ACKNOWLEDGEMENTS
We gratefully acknowledge the financial support from the National
Natural Science Foundation of China (No. 21702180), Yangzhou
University Research Startup Fund and the Priority Academic Program
Development of Jiangsu Higher Education Institutions.
[27] J. Papadopoulos, T. Müller, Dyes Pigm. 2019, 166, 357.
[28] Y. Chen, J. Guo, X. Wu, D. Jia, F. Tong, Dyes Pigm. 2018, 148, 180.
[29] Y. Lin, G. Chen, L. Zhao, W. Yuan, Y. Zhang, B. Z. Tang, J. Mater.
Chem. C 2015, 3, 112.
ORCID
Shuwei Zhang
https://orcid.org/0000-0002-1879-9063
[30] S. Gan, W. Luo, B. He, L. Chen, H. Nie, R. Hu, A. Qin, Z. Zhao, B. Z.
Tang, J. Mater. Chem. C 2016, 4, 3705.
[31] L. Biesen, N. N. Budau, K. Hoffmann, U. R. Genger, T. J. Muller,
Angew. Chem. Int. Ed. 2020, 59, 10037.
REFERENCES
[1] N. H. Mudliar, P. M. Dongre, P. K. Singh, Sens. Actuators B 2019, 301,
127089.
[32] S. Redon, G. Eucat, M. Ipuy, E. Jeanneau, I. G. Luneau, A. Ibanez, C.
Andraud, Y. Bretonnière, Dyes Pigm. 2018, 156, 116.
[33] Y. Wang, M. Yang, M. Zheng, X. Zhao, Y. Xie, J. Jin, Tetrahedron Lett.
2016, 57, 2399.
[2] Y. Ding, W. Zhu, Y. Xie, Chem. Rev. 2017, 117, 2203.
[3] J. Han, K. Burgess, Chem. Rev. 2010, 110, 5.
[4] D. Liu, J. De, H. Gao, S. Ma, Q. Ou, S. Li, Z. Qin, H. Dong, Q. Liao, B.
Xu, Q. Peng, Z. Shuai, W. Tian, H. Fu, X. Zhang, Y. Zhen, W. Hu,
J. Am. Chem. Soc. 2020, 142, 6332.
[34] J. Xu, B. Zhang, M. Jansen, L. Goerigk, W. W. H. Wong, C. Ritchie,
Angew. Chem. Int. Ed. 2017, 56, 13882.
[35] M. Zhang, M. Saha, M. Wang, Z. Zhou, B. Song, C. Lu, X. Yan, X. Li, F.
Huang, S. Yin, P. Stang, J. Am. Chem. Soc. 2017, 139, 5067.
[36] R. Hancock, Chem. Soc. Rev. 2013, 42, 1500.
[5] P. Rajamalli, N. Senthilkumar, P. Gandeepan, P. Huang, M. Huang, C.
Zheng, R. Wu, C. Yang, M. Chiu, L. Chu, H. Lin, C. Cheng, J. Am. Chem.
Soc. 2016, 138, 628.
[37] J. Yang, J. Liu, H. Neumann, R. Franke, R. Jackstell, M. Beller, Science
2019, 366, 1514.
[6] K. Albrecht, K. Matsuoka, D. Yokoyama, Y. Sakai, A. Nakayama, K.
Fujita, K. Yamamoto, Chem. Commun. 2017, 53, 2439.
[7] J. Mei, N. C. Leung, R. K. Kwok, J. Y. Lam, B. Z. Tang, Chem. Rev.
2015, 115, 11718.
[38] B. Wong, S. Friedle, S. Lippard, J. Am. Chem. Soc. 2009, 131, 7142.
[8] J. Luo, Z. Xie, J. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S. Kwok, X.
Zhan, Y. Liu, D. Zhu, B. Z. Tang, Chem. Commun. 2001, 37, 1740.
[9] S. Xu, T. Liu, Y. Mu, Y. Wang, Z. Chi, C. Lo, S. Liu, Y. Zhang, A. Lien, J.
Xu, Angew. Chem. Int. Ed. 2015, 54, 874.
SUPPORTING INFORMATION
Additional supporting information may be found online in the
Supporting Information section at the end of this article.
[10] H. Lu, Y. Zheng, X. Zhao, L. Wang, S. Ma, X. Han, B. Xu, W. Tian, H.
Gao, Angew. Chem. Int. Ed. 2016, 55, 155.
[11] J. Huang, H. Nie, J. Zeng, Z. Zhuang, S. Gan, Y. Cai, J. Guo, S. Su, Z.
Zhao, B. Z. Tang, Angew. Chem. Int. Ed. 2017, 56, 12971.
[12] Y. Hong, J. Y. Lam, B. Z. Tang, Chem. Commun. 2009, 45, 4332.
[13] R. Kwok, C. T. Leung, J. Y. Lam, B. Z. Tang, Chem. Soc. Rev. 2015, 44,
4228.
How to cite this article: Zhang S, Li D, Wang X, et al.
Aggregation-induced emission properties of pyridyl-containing
tetra-arylethenes. Luminescence. 2021;36:958–963. https://
doi.org/10.1002/bio.4023
[14] Y. Hong, J. Y. Lam, B. Z. Tang, Chem. Soc. Rev. 2011, 40, 5361.
[15] Y. Wang, T. Zhang, X. Liang, Small 2016, 12, 6451.