Tetraphenylene-Coated Near-Infrared Benzoselenodiazole Dye: AIE Behavior, Mechanochromism, and Bioimaging

Article abstract of DOI:10.1021/acs.orglett.9b02292

A D-A-D type of tetraphenylene-coating benzoselenodiazole fluorescence dye with near-infrared emission has been designed and constructed. This dye shows an obvious aggregation-induced-emission behavior. In the solid state, it exhibits a reversible mechanochromism with the changes of near-infrared emission. Furthermore, this dye can be used to track the lysosomes of living cells and images in vivo.

Full text of DOI:10.1021/acs.orglett.9b02292

Letter
pubs.acs.org/OrgLett
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
Tetraphenylene-Coated Near-Infrared Benzoselenodiazole Dye: AIE
Behavior, Mechanochromism, and Bioimaging
Fengying Ye,† Yuhong Liu,‡ Jianhua Chen,† Sheng Hua Liu,† Wenbo Zhao,*,‡ and Jun Yin*,†
†Key Laboratory of Pesticide and Chemical Biology, Ministry of Education; Hubei International Scientific and Technological
Cooperation Base of Pesticide and Green Synthesis; International Joint Research Center for Intelligent Biosensing Technology and
Health; College of Chemistry, Central China Normal University, Wuhan 430079, P.R. China
‡National and Local Joint Engineering Research, Center of Biomedical Functional Materials, Jiangsu Key Laboratory of
Bio-functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, P.R. China
S
* Supporting Information
ABSTRACT: A D−π−A−π−D type of tetraphenylene-coating benzoselenodiazole fluorescence dye with near-infrared
emission has been designed and constructed. This dye shows an obvious aggregation-induced-emission behavior. In the solid
state, it exhibits a reversible mechanochromism with the changes of near-infrared emission. Furthermore, this dye can be used to
track the lysosomes of living cells and images in vivo.
employing benzothiadiazole as the electron-withdrawing core,
n recent years, near-infrared fluorescent dyes have aroused
Itremendous attention due to their comprehensive applica- the N,N-dimethylamino group as the electron-donating unit,
tion in biological imaging, intelligent sensing, and other fields.1
and styryl as the conjugated spacer. It showed a reversible
mechanochromic behavior accompanying with fluorescence
emission switching from 685 to 725 nm. On the basis of
compound BTD-S, we further modified the molecular
structure in order to advance functional diversity of dyes and
further near-infrared fluorescence. For this purpose, first, the
original D−π−A−π−D electronic characteristics were still
reserved to obtain dye with NIR fluorescence emission.4
Second, the electron-withdrawing core benzothiadiazole was
replaced with benzoselenodiazole. By taking advantage of the
polarization effect of selenium atom, the electron-withdrawing
ability of the central nucleus was further increased so as to
reduce the lowest unoccupied molecular orbital (LUMO) in
the molecule and achieve the final outcome of fluorescence
signal red-shift.5 Third, the typical aggregation-induced
emission (AIE) agent tetraphenylethene structure was
introduced to regulate the luminescence properties of
molecules in an aggregated state.6
On one hand, as smart-sensing materials, the near-infrared
fluorescent dyes can also be used to carry out stimulus
response, defect detection, information storage, and other
activities.2 On the other hand, they exhibit plenty of superior
advantages in biological imaging such as low background
interference, high penetrating ability, and weak phototoxicity.3
Therefore, it is distinctly significant to design and develop new
near-infrared fluorescent dyes for biological imaging and smart-
responsive materials.
Previously, we have developed a series of fluorescent dyes
with D−π−A−π−D characteristics whose fluorescence spectra
all ranged from the visible to the near-infrared region and
exhibited reversible mechanochromic behavior.4 For example,
compound BTD-S described in Figure 1 was constructed by
The targeting molecule BTD-Se-TPE was synthesized
according to the synthetic route outlined in Figure 2A. First,
the benzoselenodiazole 1 obtained from the treatment of the
1,2-diaminobenzene and selenium dioxide was bromided to
afford the dibromide 2,7 which was subjected to the Heck
coupling reaction with N,N-dimethylstyrene 3 to generate the
crucial intermediate 4 in 36% yield. Another crucial
Received: July 3, 2019
Figure 1. Molecular design of BTD-Se-TPE.
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.9b02292
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Organic Letters
Letter
the maximum emission of compound BTD-Se-TPE in
dichloromethane showed an approximately 30 nm red-shift
in comparison with compound BTD-S, which could
preliminarily verify our optimization strategy that the
introduction of a large volume of selenium atoms will provide
or share less p-electrons in the π-system compared to that of
the sulfur atom, thus inducing the fluorescence emission
switching at an even longer wavelength.5 These observations
were consistent with the results of theoretical calculations.
It is known that tetraphenylethene has been widely applied
in the construction of AIE-based multifunctional optical
materials. In consideration of the existing tetraphenylethene
unit in molecules of BTD-Se-TPE, subsequent work focused
on investigating the AIE behavior of BTD-Se-TPE. In UV−vis
absorption spectra (Figure S3), no obvious changes were
observed in the mixture solution of DMSO/water along with
the increase of water fractions from 0 to 98%. For the
fluorescence spectra, it could be found that BTD-Se-TPE had
a weak fluorescence signal at 800 nm in DMSO (Figure 3A).
Figure 2. (A) Synthetic route of BTD-Se-TPE. (B) Frontier
molecular orbital profiles of BTD-Se-TPE based on TD-DFT
(B3LYP/6-31G*) calculations.
intermediate 7 was gained by means of a Suzuki coupling
reaction of bromide 5 and boronic acid 6.8 Then the further
Heck coupling reaction of intermediates 4 and 7 was utilized to
give the targeting compound BTD-Se-TPE. All new
intermediates and targeting molecules were well characterized
by NMR and mass spectrometry (Supporting Information).
In our previous reports,4 the D−π−A−π−D type
fluorescence dyes have a typical characteristic of intramolecular
charge transfer (ICT). To further understand thoroughly the
molecular structure and electronic properties, subsequently its
time-dependent density functional theory (TD-DFT) calcu-
lations were performed at the B3LYP/6-31G* level with the
Gaussian 09 program to reveal its frontier molecular orbitals
and electronic transitions.9 The maximum absorption and
corresponding molecular orbitals for these major electronic
transitions are shown in Figure 2B. According to the optimized
structure, the benzoselenodiazole core and its two linking
styrene units presented a planar configuration. The absorption
spectrum of BTD-Se-TPE contained two main electronic
transitions. One intense S0−S1 transition at around 657 nm
demonstrated a large oscillator strength of 0.7720, correspond-
ing to 98% contribution from the HOMO to LUMO
transition. The other absorption band in BTD-Se-TPE
corresponded to an S0−S5 transition with a wavelength
maximum at 366 nm, an oscillator strength of 0.5818, and
90% contribution from the HOMO to LUMO+2 transition
(Table S1). Furthermore, the electron density in the HOMO
of BTD-Se-TPE was distributed over two styrene moieties and
the benzoselenodiazole backbone of the whole molecule, while
that in the LUMO orbital had an obvious transfer toward the
benzoselenodiazole unit due to its strong electron-withdrawing
ability. In particular, such a molecular structure implied that
the emission of BTD-Se-TPE may cover the near-infrared
region.
Figure 3. (A) Fluorescence spectra in DMSO/water with different
water fractions. (B) Plot of the maximum peak fluorescence intensities
of BTD-Se-TPE in DMSO−water with different water fractions.
Inset: fluorescence images (fw; excited wavelength: 550 nm, 20 μmol/
L).
However, the fluorescence intensity decreased rapidly upon
addition of water, which was probably attributed to the effect
of the twisted intramoleclar charge transfer (TICT).10 When
the water fraction was 20−40%, the fluorescence intensity
began to enhance and reached a maximum value at water
volumes up to 40%. This process could be explained as a
possible reason for the formation of the molecular aggregation
state, which limited the free rotation of aryl groups and
reduced the nonradiative transition. At the same time, the
fluorescence quantum yield of BTD-Se-TPE with 40% water
was 1.05, which was higher than that in pure DMSO (ϕF =
0.21, Figure S3). As presented in Figure 3B, subsequently, the
fluorescence emission showed a tendency of quenching when
the water volume continued to increase up to 98%, mainly due
to the production of more compact nanoaggregate.11
Previously, we confirmed that these D−π−A−π−D types of
molecules usually have a mechanical responsive property in the
solid state.4 Accordingly, we studied its UV−vis absorption and
fluorescence spectra in the solid state. However, there were no
significant variations in the absorption spectra of BTD-Se-TPE
when ground or treated with dichloromethane (Figure S4).
Next, investigation of the mechanofluorochromic behavior of
BTD-Se-TPE was carried out. The as-prepared powder of
BTD-Se-TPE exhibited a near-infrared fluorescence with the
maximum emission at 740 nm, which red-shifted around 55
nm compared to that of BTD-S (Figures 4A,B). It showed a
higher fluorescent quantum yield (ϕF = 1.64, Figure S5).
Mechanically grinding the powder of BTD-Se-TPE induced a
To evaluate the theoretical prediction, subsequently, the
optical behavior of BTD-Se-TPE was investigated. We first
investigated its UV−vis absorption and emission in different
organic solvents with different polarity. Although the UV−vis
absorption showed few changes (Figure S1), the fluorescence
spectra of BTD-Se-TPE exhibited a remarkably red-shift along
with an increase of solvent polarity, reaching the maximum
fluorescence emission peak at 760 nm in dichloromethane
(Figure S2) as a result of the ICT effect. Meanwhile, the
conspicuous solvatochromism could also be viewed from the
fluorescence images (Figure S2B). It is worth mentioning that
B
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Figure 5. (A) Crystal structure of BTD-Se-TPE. (B) Weak
interactions (e.g., C−H···π, d = 3.641 Å, 3.754 Å, 3.438 Å, 3.370
Å; C−H···Se, d = 3.536 Å; C−H···N, d = 3.042 Å). (C) Weak
interactions (e.g., C−H···π, d = 2.965 Å, 3.672 Å, 3.365 Å). (D)
Packing view.
Figure 4. Stimuli-responsive behaviors of BTD-Se-TPE in the solid
state upon grinding and the addition of dichloromethane. (A)
Fluorescence spectra (excited wavelength: 600 nm; slit: 10 × 10). (B)
Images of the above process (above: under ambient light; below:
under 365 nm UV light). (C) PXRD of the above process. (D)
Xenogen IVIS spectrum images as prepared (a, b) and ground (c, d):
(a, c) λex = 600 nm, λem = 750 nm; (b, d) λex = 600 nm, λem = 800 nm.
there were many intermolecular weak interactions (e.g., C−
H···π, C−H···Se, C−H···N, etc.) in the crystalline state (Figure
5B,C). As a consequence of multiple weak interactions and the
large steric hindrance of the tetraphenylethene moiety, BTD-
Se-TPE in the crystalline state presented a head-to-tail,
antiparallel herringbone packing structure in Figure 5D. Such
a molecular stacking pattern afforded a large number of
cavities, providing the possibility of the slipping of molecules
and the destruction of the lattice under external forces.
The findings described above strongly encourage us to
further explore other functions. Given the basis of our work in
fluorescent dyes and bioimaging, subsequent exploration
mainly focused on application in bioimaging of living cells.
First, we evaluated the UV−vis absorption and fluorescence
spectra of BTD-Se-TPE in PBS buffer and SDS (sodium
dodecyl sulfate, 1.5 mM) solution, which showed an obvious
absorption band at 529 nm and a fluorescence emission at 740
nm (Figure S6). The result indicated that BTD-Se-TPE
showed potential for use in cell imaging. Lysosome is an
extremely vital organelle that can interact with countless
metabolic processes of substances, and the N,N-dimethylamino
group has been widely confirmed to be capable of targeting
lysosomes of living cells.12 Accordingly, MCF-7 cells were
cultured in Dulbecco’s modified Eagle’s medium (DMEM)
supplemented with 10% fetal bovine serum (FBS) and then
incubated at 37 °C under a humidified atmosphere containing
5% CO2. The cells were washed with ice-cold PBS three times
and then incubated with PBS-free fresh media. As could be
observed by viewing the confocal fluorescence microscope
images shown in Figure 6A, after the addition of BTD-Se-TPE
and incubation for 2 h, a red emission was found. Further
incubation with LysoTracker Green for 10 min indicated that
BTD-Se-TPE possessed a good capability of tracking
lysosomes of living cells. The successful imaging of BTD-Se-
TPE in cells inspired us to explore further application in vivo.
Zebrafish is considered as an ideal animal mode for imaging in
vivo. Accordingly, after zebrafish were incubated with dye
BTD-Se-TPE (10 μM) for 30 min the images displayed a
significant red-emission signal (Figure 6B). The results of
zebrafish imaging suggested that dye BTD-Se-TPE can be
used as an indicator in vivo.
significant bathochromic emission with a peak emission at 800
nm accompanied by a decrease of fluorescence intensity (ϕF =
1.02, Figure S5). More, fuming the grinding example of BTD-
Se-TPE with dichloromethane could be partially recovered and
led to a fluorescence emission at 760 nm in Figure 4A,4B.
Then the powder X-ray diffraction (PXRD) spectra were
obtained to reveal the mechanism of mechanochromism. As
illustrated in Figure 4C, the as-prepared BTD-Se-TPE
exhibited a larger number of sharp and distinct diffraction
peaks, indicating that they were all in a crystalline state. In
sharp contrast, the diffraction peaks of BTD-Se-TPE decreased
and even disappeared after mechanical stimulus, implying an
amorphous characteristic. The result suggested that the
mechanochromism was mainly attributed to the transition
from the crystalline to amorphous states. Moreover, the
amorphous state could recover the crystalline by fuming the
grinding example with dichloromethane. In view of the fact
that the variations of fluorescence during the mechanochromic
process were mainly in the near-infrared region, a Xenongen
IVIS spectrum imaging system was employed to visualize the
changes of fluorescence intensities.4b As shown in Figure 4D,
the pristine powder of BTD-Se-TPE displayed a strong
emission at 750 nm under the excitation at 600 nm.
Simultaneously, a strong emission at 800 nm was also
observed, which could be attributed to the fact that the
fluorescence of as-prepared BTD-Se-TPE covered a broad
region including 750 and 800 nm. After grinding, the
fluorescence intensity at 750 nm decreased sharply, while the
emission at 800 nm increased significantly. These observations
were in good agreement with our previous findings, which
proved that BTD-Se-TPE can switch from 740 to 800 nm
upon mechanical grinding.
To gain further insight into the molecular structure in the
solid state, we cultivated a single crystal of BTD-Se-TPE
suitable for crystallographic analysis by slow diffusion of
hexane into a dichloromethane solution of BTD-Se-TPE.
According to the crystal structure in Figure 5A, it can be found
that the benzoselenodiazole core and its linking two styrene
units of BTD-Se-TPE presented a good planar configuration,
which was consistent with the TD-DFT calculations. More,
In summary, we have developed a near-infrared multifunc-
tional fluorescent dye that had obvious AIE characteristics in
C
DOI: 10.1021/acs.orglett.9b02292
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Letter
Ministry-Province Jointly Constructed Base for State Key Lab-
Shenzhen Key Laboratory of Chemical Biology (Shenzhen),
State Key Laboratory of Materials-Oriented Chemical
Engineering (KL17-10), Open Project Fund of Key Laboratory
of Natural Resources of Changbai Mountain & Functional
Molecules (Yanbian University, NRFM201701), Ministry of
Education, the foundation of Key Laboratory of Synthetic and
Biological Colloids, Ministry of Education, Jiangnan University
(No. JDSJ2017-07), and self-determined research funds of
CCNU from the colleges’ basic research and operation of
MOE (CCNU18TS012). Finally, in particular, we thank
Professor Qin Yang at Sichuan University for the measurement
of fluorescence quantum yields and Professor Na Zhao at
Shaanxi Normal University for her good suggestion about AIE
measurements.
Figure 6. (A) Confocal microscopy fluorescence imaging of MCF-7
cells stained with LysoTracker Green and BTD-Se-TPE: (a) blank;
(b) red channel; (c) green channel; (d) the merged channel. (B)
Zebrafish fluorescence imaging of BTD-Se-TPE: (e) blank; (f) red
channel; (g) merged image.
REFERENCES
■
(1) (a) Luo, X.; Li, J.; Zhao, J.; Gu, L.; Qian, X.; Yang, Y. Chin.
Chem. Lett. 2019, 30, 839−846. (b) Cai, Y.; Wei, Z.; Song, C.; Tang,
C.; Han, W.; Dong, X. Chem. Soc. Rev. 2019, 48, 22−37. (c) Ding, F.;
Zhan, Y.; Lu, X.; Sun, Y. Chem. Sci. 2018, 9, 4370−4380. (d) Zhao,
Q.; Sun, J. Z. J. Mater. Chem. C 2016, 4, 10588−10609. (e) Suzuki,
N.; Suda, K.; Yokogawa, D.; Kitoh-Nishioka, H.; Irle, S.; Ando, A.;
the near-infrared region. In the solid state, this dye presented a
reversible mechanochromism with near-infrared emission.
Upon external grinding, its emission was able to switch to
800 nm from 740 nm. In particular, this dye could be applied
in living cells and had the capability to track the lysosome and
zebrafish imaging. We hope this work will be helpful in the
design and development of multifunctional near-infrared
materials with high functional performance in the future.
Abegao, L. M. G.; Kamada, K.; Fukazawa, A.; Yamaguchi, S. Chem.
̃
Sci. 2018, 9, 2666−2673. (f) Chen, Y.; Li, L.; Chen, W.; Chen, H.;
Yin, J. Chin. Chem. Lett. 2019, 30, 1353−1360.
(2) (a) Chen, W.; Pan, Y.; Chen, J.; Ye, F.; Liu, S. H.; Yin, J. Chin.
Chem. Lett. 2018, 29, 1429−1435. (b) Wang, H.; Mu, X.; Yang, J.;
Liang, Y.; Zhang, X. D.; Ming, D. Coord. Chem. Rev. 2019, 380, 550−
571. (c) Kim, J. H.; Yun, J. H.; Lee, J. Y. Adv. Opt. Mater. 2018, 6,
1800255. (d) Ni, Y.; Wu, J. Tetrahedron Lett. 2016, 57, 5426−5434.
(3) (a) Fan, Y.; Zhang, F. Adv. Opt. Mater. 2019, 7, 1801417.
(b) Zhu, S.; Yung, B. C.; Chandra, S.; Niu, G.; Antaris, A. L.; Chen, X.
Theranostics 2018, 8, 4141−4151. (c) Wu, D.; Chen, L.; Lee, W.; Ko,
G.; Yin, J.; Yoon, J. Coord. Chem. Rev. 2018, 354, 74−97. (d) Zhu, H.;
Cheng, P.; Chen, P.; Pu, K. Biomater. Sci. 2018, 6, 746−765. (e) Li,
C.; Wang, Q. ACS Nano 2018, 12, 9654−9659. (f) Kenry; Duan, Y.;
Liu, B. Adv. Mater. 2018, 30, 1802394. (g) Aguirre, J.; Schwarz, M.;
Garzorz, N.; Omar, M.; Buehler, A.; Eyerich, K.; Ntziachristos, V. Nat.
Biomed. Eng. 2017, 1, 0068. (h) Deng, K.; Li, C.; Huang, S.; Xing, B.;
Jin, D.; Zeng, Q.; Hou, Z.; Lin, J. Small 2017, 13, 1702299.
(i) Chernov, K. G.; Redchuk, T. A.; Omelina, E. S.; Verkhusha, V. V.
Chem. Rev. 2017, 117, 6423−6446. (j) Owens, E. A.; Henary, M.; El
Fakhri, G.; Choi, H. S. Acc. Chem. Res. 2016, 49, 1731−1740.
(k) Guo, Z.; Park, S.; Yoon, J.; Shin, J. Chem. Soc. Rev. 2014, 43, 16−
29.
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.or-
glett.9b02292.
Specific synthesis routes, NMR data and MS spectra,
spectroscopic data, and crystallographic data of com-
pound BTD-Se-TPE (PDF)
Accession Codes
CCDC 1922749 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cam-
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(4) (a) Chen, J.; Ye, F.; Lin, Y.; Chen, Z.; Liu, S. H.; Yin, J. Sci.
China: Chem. 2019, 62, 440−450. (b) Chen, J.; Li, D.; Chi, W.; Liu,
G.; Liu, S. H.; Liu, X.; Zhang, C.; Yin, J. Chem. - Eur. J. 2018, 24,
3671−3676.
(5) (a) Calitree, B.; Donnelly, D. J.; Holt, J. J.; Gannon, M. K.;
Nygren, C. L.; Sukumaran, D. K.; Autschbach, J.; Detty, M. R.
Organometallics 2007, 26, 6248−6257. (b) Wu, W.; Yang, Y.; Yang,
Y.; Yang, Y.; Zhang, K.; Guo, L.; Ge, H.; Chen, X.; Liu, J.; Feng, H.
Small 2019, 15, 1805549.
(6) (a) Yang, Q.; Li, D.; Chi, W.; Guo, R.; Yan, B.; Lan, J.; Liu, X.;
Yin, J. J. Mater. Chem. C 2019, 7, 8244−8249. (b) Han, X.; Liu, Y.;
Liu, G.; Luo, J.; Liu, S. H.; Zhao, W.; Yin, J. Chem. - Asian J. 2019, 14,
890−895. (c) Ma, X.; Hu, L.; Han, X.; Yin, J. Chin. Chem. Lett. 2018,
29, 1489−1492. (d) Han, X.; Li, D.; Ma, X.; Liu, S. H.; Yin, J. New J.
Chem. 2018, 42, 6609−6612. (e) Han, X.; Zhang, B.; Chen, J.; Liu, S.
H.; Tan, C.; Liu, H.; Lang, M. J.; Tan, Y.; Liu, X.; Yin, J. J. Mater.
Chem. B 2017, 5, 5096−5100.
(7) (a) Idris, I.; Tannoux, T.; Derridj, F.; Dorcet, V.; Boixel, J.;
Guerchais, V.; Soule, J. F.; Doucet, H. J. Mater. Chem. C 2018, 6,
1731−1737. (b) Chen, C. P.; Wu, P. J.; Liou, S. Y.; Chan, Y. H. RSC
Adv. 2013, 3, 17507−17514.
AUTHOR INFORMATION
Corresponding Authors
■
*E-mail: yinj@mail.ccnu.edu.cn.
*E-mail: zhaowenbo@njnu.edu.cn.
ORCID
Wenbo Zhao: 0000-0001-7808-0125
Jun Yin: 0000-0003-4732-6123
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We acknowledge financial support from the National Natural
Science Foundation of China (21676113, 21402057,
21772054, 21472059), Distinguished Young Scholar of
Hubei Province (2018CFA079), Youth Chen-Guang Project
of Wuhan (2016070204010098), 111 Project B17019, the
D
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Letter
(8) Huang, Z.; Zhang, X.; Zhang, X.; Wang, S.; Yang, B.; Wang, K.;
Yuan, J.; Tao, L.; Wei, Y. RSC Adv. 2015, 5, 89472−89477.
(9) (a) Xu, Z.; Huang, X.; Han, X.; Wu, D.; Zhang, B.; Tan, Y.; Cao,
M.; Liu, S. H.; Yin, J.; Yoon, J. Chem. 2018, 4, 1609−1628. (b) Liu,
G.; Chen, W.; Xu, Z.; Ye, F.; Pan, Y.; Chen, X.; Liu, S. H.; Zeng, L.;
Yin, J. Org. Biomol. Chem. 2018, 16, 5517−5523. (c) Han, X.; Hu, F.;
Chi, W.; Ma, X.; Liu, S. H.; Liu, X.; Yin, J. Sens. Actuators, B 2018,
277, 55−61. (d) Liu, G.; Han, X.; Zhang, J.; Xu, Z.; Liu, S. H.; Zeng,
L.; Yin, J. Dyes Pigm. 2018, 148, 292−297. (e) Xu, Z.; Ge, H.; Han,
X.; Liu, S. H.; Meng, X.-G.; Yin, J. Tetrahedron 2017, 73, 6386−6391.
(10) (a) Liu, J.; Chen, C.; Ji, S.; Liu, Q.; Ding, D.; Zhao, D.; Liu, B.
Chem. Sci. 2017, 8, 2782−2789. (b) Hu, R.; Lager, E.; Aguilar-Aguilar,
A. L.; Liu, J.; Lam, J. W. Y.; Sung, H. H. Y.; Williams, I. D.; Zhong, Y.;
Wong, K. S.; Pena-Cabrera, E.; Tang, B. Z. J. Phys. Chem. C 2009,
̃
113, 15845−15853. (c) Gao, S.; Wei, G.; Zhang, S.; Zheng, B.; Xu, J.;
Chen, G.; Li, M.; Song, S.; Fu, W.; Xiao, Z.; Lu, W. Nat. Commun.
2019, 10, 2206.
(11) (a) Xiong, J.; Wang, K.; Yao, Z.; Zou, B.; Xu, J.; Bu, X. H. ACS
Appl. Mater. Interfaces 2018, 10, 5819−5827. (b) Luo, J.; Xie, Z.; Lam,
J. W. Y.; Cheng, L.; Chen, H.; Qiu, C.; Kwok, H. S.; Zhan, X.; Liu, Y.;
Zhu, D.; Tang, B. Z. Chem. Commun. 2001, 1740−1741.
(12) (a) Gao, P.; Pan, W.; Li, N.; Tang, B. Z. Chem. Sci. 2019, 10,
6035−6071. (b) Niu, G.; Zhang, P.; Liu, W.; Wang, M.; Zhang, H.;
Wu, J.; Zhang, L.; Wang, P. Anal. Chem. 2017, 89, 1922−1929.
E
DOI: 10.1021/acs.orglett.9b02292
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