Efficient light emitters in the solid state: Synthesis, aggregation-induced emission, electroluminescence, and sensory properties of luminogens with benzene cores and multiple triarylvinyl peripherals

Article abstract of DOI:10.1002/adfm.201102030

Benzene-cored luminogens with multiple triarylvinyl units are designed and synthesized. These propeller-shaped molecules are nonemissive when dissolved in good solvents, but become highly emissive when aggregated in poor solvents or in the solid state, showing the novel phenomenon of aggregation-induced emission. Restriction of intramolecular motion is identified as the main cause for this effect. Thanks to their high solid-state fluorescence quantum yields (up to unity) and high thermal and morphological stabilities, light-emitting diodes with the luminogens as emitters give sky-blue to greenish-blue light in high luminance and efficiencies of 10800 cd m^-2, 5.8 cd A^-1, and 2.7%, respectively. The emissions of the nanoaggregates of the luminogens can be quenched exponentially by picric acid, or selectively by Ru³⁺, with quenching constants up to 10⁵ and ～2.0 × 10 ⁵ L mol^-1, respectively, making them highly sensitive (and selective) chemosensors for explosives and metal ions. Benzene-cored luminogens with multiple triarylvinyl units exhibit aggregation-induced emission. The high solid-state fluorescence quantum yields and high thermal and morphological stabilities of such emitters gave light-emitting diodes with sky-blue to greenish-blue light in high luminance and efficiencies. The emission could be quenched exponentially by picric acid, or selectively by Ru³⁺, making them highly sensitive (and selective) chemosensors for explosives and metal ions. Copyright

Full text of DOI:10.1002/adfm.201102030

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Efficient Light Emitters in the Solid State: Synthesis,
Aggregation-Induced Emission, Electroluminescence,
and Sensory Properties of Luminogens with Benzene Cores
and Multiple Triarylvinyl Peripherals
Carrie Y. K. Chan, Zujin Zhao, Jacky W. Y. Lam, Jianzhao Liu, Shuming Chen, Ping Lu,
Faisal Mahtab, Xiaojun Chen, Herman H. Y. Sung, Hoi Sing Kwok, Yuguang Ma,
Ian D. Williams, Kam Sing Wong, and Ben Zhong Tang*
1. Introduction
Benzene-cored luminogens with multiple triarylvinyl units are designed and
Scientists and technologists have devoted
synthesized. These propeller-shaped molecules are nonemissive when dis-
much effort to the development of sensi-
solved in good solvents, but become highly emissive when aggregated in
tive and selective sensory systems for the
poor solvents or in the solid state, showing the novel phenomenon of aggre-
gation-induced emission. Restriction of intramolecular motion is identified as
the main cause for this effect. Thanks to their high solid-state fluorescence
quantum yields (up to unity) and high thermal and morphological stabilities,
light-emitting diodes with the luminogens as emitters give sky-blue to greenish-
blue light in high luminance and efficiencies of 10800 cd m−2, 5.8 cd A−1, and
2.7%, respectively. The emissions of the nanoaggregates of the luminogens can
be quenched exponentially by picric acid, or selectively by Ru3+, with quenching
constants up to 105 and ∼2.0 × 105 L mol−1, respectively, making them highly
sensitive (and selective) chemosensors for explosives and metal ions.
detection of chemicals, metals, and biopoly-
mers, because they play important roles
in industrial, environmental, and biolog-
ical processes and systems. Sensors based
on fluorescent materials have attracted
special attention, as they offer ultrahigh
sensitivity, ultralow detection limits, great
interference tolerance, and specific-analyte
targeting, in addition to their ultrafast
response, simple operation, field porta-
bility, and in-situ workability.[1] In response
to the demand, a large number of lumi-
nescent molecules have been synthesized.
Many are highly emissive in dilute solu-
tions, with fluorescence quantum yields approaching unity. On
the other hand, many chemical and biological analytes are ionic
species existing or working in aqueous media. Incongruously,
however, most fluorophores are hydrophobic aromatics that are
barely soluble in water. Although their water miscibility can be
improved by incorporating hydrophilic groups, the resultant
amphiphilic molecules tend to aggregate when dispersed in
aqueous media. Formation of aggregates often partially—and
sometimes even totally—quenches the light emission. This
notorious effect of aggregation-caused quenching (ACQ) has
led fluorophores to be studied as isolated molecules in very
dilute solutions.[2] The use of dilute solutions, however, leads
to poor sensitivity in fluorescence sensory systems. Inorganic
quantum dots can surmount some of the disadvantages of the
organic fluorophores, but they also pose new problems, such as
the difficulty of their syntheses, the limited varieties, and their
inherently high toxicities.[3]
C. Y. K. Chan, Dr. Z. Zhao, Dr. J. W. Y. Lam, Dr. J. Liu, Dr. F. Mahtab,
Dr. H. H. Y. Sung, Prof. I. D. Williams, Prof. B. Z. Tang
Department of Chemistry
The Hong Kong University of Science & Technology (HKUST)
Clear Water Bay, Kowloon
Hong Kong, P. R. China
Fax: +852-2358-1594
E-mail: tangbenz@ust.hk
S. Chen, Prof. H. S. Kwok
Center for Display Research
HKUST, Clear Water Bay, Kowloon
Hong Kong, P. R. China
Dr. P. Lu, Prof. Y. Ma
State Key Laboratory of Supermolecular Structure and Materials
Jilin University
Changchun 150012, P. R. China
X. Chen, Prof. K. S. Wong
Department of Physics
HKUST, Clear Water Bay, Kowloon
Hong Kong, P. R. China
In our research for efficient light-emitting materials, we were
attracted by a group of novel molecules called siloles. These
molecules are practically nonfluorescent when dissolved in good
solvents as isolated species, but become highly emissive when
aggregated into nanoparticles in poor solvents (e.g., water) or
fabricated into thin films in the solid state.[4] We coined the
Prof. B. Z. Tang
Department of Polymer Science and Engineering
Zhejiang University
Hangzhou 310027, P. R. China
DOI: 10.1002/adfm.201102030
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term “aggregation-induced emission (AIE)” for this phenom-
enon because the nonemissive silole molecules do emit on
formation of aggregates. Recently, we and other groups found
that other conjugated compounds also exhibit AIE activity.[5] For
example, while trans-1,4-distyrylbenzene is a traditional ACQ
fluorophore, Diau, Hsu, and co-workers found that attaching
two methyl groups to the double bonds of 1,4-distyrylbenzene
can transform it into an AIE fluorogen.[6] Wu et al. observed
marked AIE effects for a series of 8,8a-dihydrocyclopenta[a]
indene derivatives.[7] Tao et al. reported the AIE feature of a
Λ-shaped pyridinium salt.[8] Wang and co-workers integrated
benzobis(thiadiazole) with triphenylamine and generated an
AIE-active molecule with an emission maximum in the near-
IR region.[9] Chujo and co-workers observed a similar AIE
effect in polymers with o-carborane and p-phenyleneethynylene
sequences.[10] Li and Park reported a series of Ir(III) complexes
with aggregation-induced phosphorescence characteristics.[11]
The AIE systems developed so far range from hydrocarbons
to organometallics, from small molecules to big polymers, and
from extensively conjugated systems to those without typical
chromophores, which is demonstrative of the ubiquity of the
AIE effect.
AIE fluorogens have been used for the fabrication of efficient
optoelectronic devices.[12] In contrast, much less work has been
carried out on their applications in environmental and biolog-
ical sciences.[13] In this paper, we aim to synthesize new AIE
luminogens with potential applications in these fields. We pre-
pared benzene-cored luminogens carrying multiple triarylvinyl
peripherals and found that they were all AIE-active with high
solid-state-fluorescence quantum yields. Organic light-emitting
diodes (OLEDs) based on the luminogens were constructed,
which showed sky-blue and greenish-blue light in high lumi-
nance and efficiency. These emissions could be faded by picric
acid, and selectively by Ru3+, with large quenching constants,
which renders them promising chemosensors for explosives
and metal ions.
2. Results and Discussion
2.1. Synthesis
To enrich the AIE research and broaden its practical appli-
cations, we designed three new AIE luminogens and
devised a multistep reaction route for their syntheses
(Scheme 1). The Friedel–Crafts acylation of terephthaloyl
chloride (1) with benzene furnished 2, which was converted
into TPTPE by reaction with diphenylmethyl lithium (4)
followed by acid-catalyzed dehydration. Using similar syn-
thetic procedures, we also prepared TPTDPE and BTPTPE
with thiophene and additional 1,2,2-triphenylvinyl substit-
uents, respectively.
All intermediates and final products were carefully puri-
fied and fully characterized by NMR and mass spectroscopies,
which confirmed their expected molecular structures. Single
crystals of TPTPE, TPTDPE, and BTPTPE were isolated from
their dichloromethane (DCM)/methanol solutions, and were
characterized crystallographically. Their ORTEP drawings are
shown in Figure 1, while Table 1 and Table S1−S3 in the Sup-
porting Information summarize the crystal data. Note that
Wang had prepared TPTPE by a three-step synthetic route but
failed to obtain its crystal structure.[14] Instead of investigating
its optical and electrochemical properties, however, no effort
was made on the exploration of its practical applications. All the
luminogens were soluble in common organic solvents, such
as tetrahydrofuran (THF), toluene, DCM, and chloroform, but
were insoluble in water.
Li
Ar
(4), THF
1.
Cl
O
Ar
O
Ar
H
Ar
AlCl3, DCM
2. TsOH, toluene
O
Cl
O
Ar
1
Ar =
2,
3
S
Ar =
TPTPE,
TPTDPE
S
O
O
Cl
Cl
4
1. , THF
AlCl3
benzene
2. TsOH, toluene
O
O
O
O
Cl
5
4
BTPTPE
Scheme 1. Synthetic routes to TPTPE, TPTDPE, and BTPTPE.
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0.09%, respectively, which indicates that they are practically
nonluminescent when dissolved in good solvents.
To investigate whether the new luminogens are AIE-active,
we added water, a nonsolvent for the luminogens, to the THF
solutions and monitored the PL change. The PL intensity of
TPTPE remains low in aqueous mixtures with water content
less than 70%, above which it increases swiftly. From the pure
THF solution to THF/H2O mixture with 90% water content,
the PL intensity rises 1000 fold. Particle-size analysis of the
aqueous mixtures with high water content confirms the forma-
tion of nanoparticles with average sizes of 120–200 nm. Clearly,
the PL of TPTPE is enhanced by aggregate formation; in other
words, it is AIE-active. The AIE phenomenon is not an isolated
case observed only in TPTPE but is also found in TPTDPE and
BTPTPE.
Closer inspection of the PL spectra of BTPTPE in aqueous
mixtures reveals that the emission maximum is bathochromi-
cally shifted from 450 to 460 nm, and that this shift is accom-
panied by a reduction in intensity when the water content is
increased from 85 to 90 and then to 95%.This is due to the mor-
phological change in the aggregates from crystalline to amor-
phous: In solvent mixtures with low water content (≤50%), the
molecules steadily assemble into crystalline clusters, whereas
in mixtures with high water fractions (>85%), the molecules
abruptly agglomerate into amorphous aggregates, as confirmed
by transmission electron microscope (TEM) and electron dif-
fraction (ED) measurements. Whilst clear diffraction spots are
seen in the ED pattern of the aggregates of BTPTPE formed in
50% aqueous mixture, the aggregates formed in 95% aqueous
mixture give only a diffuse halo (Figure 4).
To better understand the photophysical properties of the
luminogens, we performed theoretical calculations on their
energy levels. Their highest-occupied molecular orbital (HOMO)
and lowest occupied molecular orbital (LUMO) plots are shown
in Figure 5. The HOMO and LUMO of TPTPE and TPTDPE
are dominated by the orbitals from the benzene core and the
triarylvinyl units, which reveals that their absorption and emis-
sion stem from the π–π* transitions and exciton decays of the
whole molecules. However, the severe steric hindrance between
the peripherals in BTPTPE leads to poorer electronic commu-
nication. As a result, the orbitals are mainly localized on the
benzene core conjugated with one or two triphenylvinyl units.
Such orbital distribution has somewhat shortened the effec-
tive conjugation length. The calculated bandgap for BTPTPE
is 4.226 eV, which is wider than those of TPTPE and TPTDPE
(4.018 and 3.695 eV, respectively). The theoretical study thus
nicely explains the hypsochromic shifts in the absorption and
emission of BTPTPE relative to those of TPTPE and TPTDPE.
We further investigated the PL behaviors of the luminogens
in the solid state. The emissions of the TPTPE, TPTDPE, and
BTPTPE films show a peak at 480–450 nm, which is similar
to the PLs of their aggregates in THF/H2O mixtures (Table 2).
In sharp contrast to their weak fluorescence in solution, all the
luminogens emit strongly in the condensed phase, with ΦF
values (measured by an integrating sphere) of 100, 25.5, and
100%, respectively.
Figure 1. ORTEP drawings of TPTPE, TPTDPE, and BTPTPE.
2.2. Optical Properties
Figure 2 shows the absorption spectra of the benzene-cored
luminogens in dilute THF (10 μm). The ultraviolet (UV) spectra
of TPTPE and TPTDPE are similar, with peak maxima at 326
and 332 nm, respectively. The spectrum of BTPTPE, however, is
blueshifted relative to those of TPTPE and TPTDPE, albeit at a
higher absorptivity, which suggests that it possesses lower con-
jugation. This can be understood because the triarylvinyl units
of TPTPE and TPTDPE interact electronically on the same plane
via the benzene core, whereas those of BTPTPE are metaconju-
gated, which leads to a shorter effective conjugation length in
BTPTPE and hence absorption at the shorter wavelengths.
The photoluminescence (PL) spectra of TPTPE, TPTDPE,
and BTPTPE in dilute THF (10 μm) exhibit only noisy PL sig-
nals with no discernible peak maxima (Figure 3 and Figure S1
in the Supporting Information). The fluorescence quantum
yields (ΦFS) of TPTPE, TPTDPE, and BTPTPE, estimated using
9,10-diphenylanthracene as standard, are merely 0.22, 0.11, and
We proposed that the restriction of intramolecular rotation
(IMR) is the main cause for the AIE.[15] In dilute solution, the
multiple aromatic rings in TPTPE, TPTDPE, and BTPTPE can
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Table 1. Summary of crystal data and reflection collection parameters for TPTPE, TPTDPE, and BTPTPE.
TPTPE
C46H34
TPTDPE
C42H30S2
598.78
BTPTPE
empirical formula
C67.75H52.50Cl2.50O0.50
formula weight
586.73
963.22
0.32 × 0.25 × 0.03
monoclinic
P2(1)/c
crystal dimensions [mm]
0.40 × 0.15 × 0.12
triclinic
0.30 × 0.28 × 0.15
monoclinic
P2(1)/c
crystal system
space group
a [Å]
P–1
10.129(3)
12.382(4)
14.475(5)
99.928(5)
100.985(5)
106.356(4)
1660.0(10)
2
12.1008(4)
9.3658(3)
14.6950(5)
90
12.7233(3)
17.5697(3)
24.5934(5)
90
b [Å]
c [Å]
α [deg]
β [deg]
γ [deg]
V [Å3]
108.772(4)
90
92.341(2)
90
1576.85(9)
2
5493.1(2)
4
Z
Dcalcd. [g cm−3
F000
]
1.174
1.261
1.165
620
628
2022
Temp [K]
298(2)
173(2)
133(2)
0.71073
1.54178
1.54178
Radiation (λ), [Å]
μ (Mo Kα) [mm−1
0.066
1.742
1.593
]
25 (98.7%)
15329
66.5 (98.2%)
8133
66.5 (98.2%)
30269
2θmax [deg] (completeness)
no. of collected reflns.
no. of unique reflns. (Rint
)
6402 (0.0396)
6402/0/415
0.0547, 0.0893
0.1130, 0.0992
0.161/–0.121
1.00/0.88
1.005
2792 (0.0331)
2792/0/199
0.0441, 0.1225
0.0526, 0.1274
0.428/–0.296
1.00/0.76
1.012
9720 (0.0724)
9720/4/649
0.0641, 0.1494
0.1033, 0.1603
0.647/–0.672
1.00/0.60
1.008
data/restraints/parameters
R1, wR2 [obs I> 2σ (I)]
R1, wR2 (all data)
residual peak/hole e. Å−3
transmission ratio
goodness-of-fit on F2
undergo active IMR. Collectively, these multiple molecular
motions effectively consume the photonic energy of the excited
state as thermal energy, which consequently quenches the light
emission of the luminogens in pure THF. In the aggregated or
film state, the IMR process is restricted, which blocks the non-
radiative relaxation pathway and populates radiative decay, thus
turning the dye molecules into strong emitters.
Interestingly, the crystals of TPTPE, TPTDPE, and BTPTPE
emit at 435–455 nm, which is 12–57 nm blueshifted from those
of the amorphous films. Similar phenomena were also observed
in other TPE derivatives.[16] The unusual blueshift observed in
the crystalline phase may be attributable to the conformation
twisting of the aromatic rings of the luminogens to fit into the
crystalline lattices. Without such restraint, the molecules in the
amorphous state may assume a more planar conformation and
thus show a redder luminescence.
which prevents the formation of species that are detrimental
to light emission by intermolecular interactions. Multiple
C—H···π hydrogen bonds with distances of 2.745−2.888 Å are
formed between the hydrogen atoms of the phenyl rings in one
molecule and the π clouds of the phenyl rings in another mole-
cule. These multiple C—H···π hydrogen bonds help rigidify
the molecular conformation and lock the molecular rotation. As
a result, the excited-state energy consumed by IMR is greatly
reduced, thus enabling the molecules to emit intensely in the
solid state.
2.3. Thermal Properties
The thermal stability of TPTPE, TPTDPE, and BTPTPE was
evaluated by thermogravimetric analysis (TGA) under nitrogen
at a heating rate of 10 °C min−1. As shown in Figure 7, all the
luminogens are thermally stable, losing 5% of their weights at
temperatures (Td) from 293 to 338 °C. Their phase transitions
were investigated by differential scanning calorimetry (DSC)
To gain further insight into the AIE mechanism, we exam-
ined the geometric structures and packing arrangements of
TPTPE, TPTDPE, and BTPTPE in the crystalline state. As shown
in Figure 6, all the luminogens take a twisted conformation,
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5
BTPTPE
4
3
2
1
TPTDPE
TPTPE
0
250
300
350
Wavelength (nm)
400
450
Figure 2. Absorption spectra of THF solutions of TPTPE, TPTDEP, and
BTPTPE. Solution concentration: 10−5m.
at a heating rate of 10 °C min−1. All compounds exhibit clear
melting transitions (Tm) in the range from 205 to 282 °C. Partic-
ularly, the second heating scan of BTPTPE detects a glass-tran-
sition temperature (Tg) at 113 °C, suggesting that it possesses
high morphological stability. The Tgs of TPTPE and TPTDPE
are not detected, probably due to their low molecular weights.
Figure 4. a,b) TEM images and (c,d) ED patterns of (a,c) crystalline and
(b,d) amorphous aggregates of BTPTPE formed in THF/H2O mixtures
with water content of 80 and 95 vol%, respectively.
(100 nm) were fabricated, where TPTPE, TPTDPE, or BTPTPE
worked as a light-emitting layer (LEL), NPB functioned as a
hole-transport material, and TPBi served as a hole-blocking as
well as electron-transport layer, respectively. The EL perform-
ances of TPTPE are shown in Figure 8 as an example, while
those of TPTDPE and BTPTPE are summarized in Table 3. The
device of TPTPE is turned on at 4.2 V and emits a bright sky-
blue EL at 488 nm with luminance up to 10800 cd m−2 at 15 V.
The maximum current and external quantum efficiencies of
the device reach 5.8 cd A−1 and 2.7%, respectively. Although the
device configuration is yet to be optimized, the good EL data
2.4. Electroluminescence
The efficient light emissions of TPTPE, TPTDPE, and BTPTPE
encouraged us to investigate their electroluminescence (EL)
properties. Multilayer OLEDs with a configuration of indium
tin oxide (ITO)/N,N-bis(1-naphthyl)-N,N-diphenylbenzidine
(NPB) (60 nm)/LEL (20 nm)/2,2′,2″-(1,3,5-benzinetriyl)-tris(1-
phenyl-1H-benzimidazole) (TPBi) (40 nm)/LiF (1 nm)/Al
1000
b)
a)
200
180
160
140
120
100
95%
Water fraction
(vol %)
800
600
400
200
0
95
0
78
83
88
93
Water fraction (vol %)
80%
0
20
40
60
80
100
380
432
484
536
588
640
Water fraction (vol %)
Wavelength (nm)
Figure 3. a) PL spectra of TPTPE in THF and THF/H2O mixtures. Concentration: 10−5m; excitation wavelength: 330 nm. b) Plot of (I/I0–1) values
versus the compositions of the THF/H2O mixtures. Inset: particle sizes of the nanoaggregates of TPTPE formed in THF/H2O mixtures with various
water fractions.
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TPTPE
2.745
2.745
TPTDPE
2.782
2.782
Figure 5. Molecular orbital amplitude plots of HOMO and LUMO levels of
TPTPE, TPTDPE, and BTPTPE calculated using the B3LYP/6-31G* basis set.
BTPTPE
clearly demonstrate the high potential of TPTPE as a solid-state
light emitter in the construction of efficient EL devices.
The ELs of TPTDPE and BTPTPE are observed at 512 and
448 nm. Their EL performances, however, are much poorer
than those of TPTPE. This demonstrates that the EL properties
of the luminogens are sensitive to their molecular structures,
which enables us to further enhance their device performances
by molecular engineering.
2.888
2.888
2.849
2.849
2.5. Explosive Detection
Figure 6. Perspective view of the packing arrangements in crystals of
TPTPE, TPTDPE, and BTPTPE. The aromatic C—H···π hydrohen bonds
are denoted by dotted lines.
Efficient fluorescent chemosensors for nitroaromatic explosives
such as 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, and 2,4,6-
trinitrophenol (picric acid; PA) are in great demand because
of the threat from the increased use of explosives in terrorism
acts.[17] Inspired by the AIE characteristics of TPTPE, TPTDPE,
and BTPTPE, we explored their utility as chemosensors for sen-
sitive detection of explosives. Their nanoaggregates in THF/H2O
mixtures (1:9 by volume) are utilized as probes for the
detection. PA was chosen as a model compound because of its
commercial availability. We investigated the quenching process
by monitoring the PL change in response to the PA addition.
As depicted in Figure 9, the emissions of the luminogens are
progressively weakened when an increasing amount of PA is
added to their THF/H2O mixtures. The fluorescence quenching
can be clearly discerned at a [PA] as low as 1 μg mL−1 or
1 ppm. At a PA concentration of 12 μg mL−1, there are almost
no PL signals, which reveals their high sensitivity towards PA
detection.
Remarkably, all the Stern–Volmer plots of relative PL
intensity (I0/I) versus PA concentration give curves bending
upward, instead of linear lines (Figure 9c). This indicates
that PL quenching becomes more efficient with increasing
quencher concentration. We have recently shown that the
static quenching model was more appropriate than the dif-
fusion-controlled dynamic mechanism to describe the PL
annihilation of hyperbranched conjugated polymers by PA
analytes.[18] Such a rationalization may also apply here.
TPTPE, TPTDPE, and BTPTPE can somewhat act as elec-
tron donors and have electrostatic interaction or charge
transfer with PA, which leads to the formation of non-
emissive ground-state dark complexes but maintaining the
natural lifetimes of their unbound luminogens. However,
in the diffusion-controlled dynamic quenching model, the
PL lifetime is shortened with an increase in the quencher
Table 2. Optical properties of TPTPE, TPTDPE, and BTPTPE in solution
(Soln)a), aggregate (Aggr)b), crystalline (Cryst), and amorphous (Amor)
states.
λabc) [nm]
λemd) [nm] (ΦFe) [%])
Compound
Solnf)
Aggr
485
495
460
Amor
Cryst
455
435
438
TPTPE
326
332
313
nd (0.22)
nd (0.11)
nd (0.09)
480 (100.0)
492 (25.5)
450 (100.0)
TPTDPE
BTPTPE
a)In dilute THF solution (10 μm); b)In THF/H2O mixture (1:9 by volume);
c)Absorption maximum in THF; d)Emission maximum; e)Fluorescence quantum
yield determined using 9,10-diphenylanthracene (ΦF = 90% in cyclohexane) as
standard (for solution sample) or measured by a calibrated integrating sphere (for
solid sample); f)nd = not determined because of the weak PL signals.
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b)
a)
100
80
60
40
20
0
TPTPE
Tm = 238 oC
TPTDPE
BTPTPE
T
d (oC)
Tm = 282 oC
TPTPE
304
TPTDPE 293
BTPTPE 338
Tm = 205 oC
1st heating
Tg = 113 oC
2
nd heating
80
160
240
320
400
480
60
120
180
240
300
Temperature ( oC)
Temperature ( oC)
Figure 7. a) TGA and b) DSC thermograms of TPTPE, TPTDPE, and BTPTPE recorded under nitrogen at a heating rate of 10 °C min−1.
concentration.[19] To verify which model is responsible for
I0
= 1.40e46157[PA] − 0.35
(2)
the PL quenching process of the present luminogens, the
dependence of their lifetimes on the PA concentration is
investigated. As shown in Figure S2 and Table S4 in the
Supporting Information, the weighted mean lifetimes of
the dyes remain almost unchanged in the presence of dif-
ferent amounts of PA, which suggests that PL quenching is
through the static mechanism.
I
I0
I
= 2.85e37029[PA] − 1.86
= 1.08e61708[PA] − 0.02
(3)
(4)
I0
I
Equation 1 can be used to describe the PL annihilation by
the static mechanism:
Generalization from Euation 2 to 4 gives Equation 5, which is
different from Equation 1 by having two extra constants (A and
B), although they are both single exponential-growth functions.
I0
= eV [PA]
q
I
(1)
I0
= Aek[PA] + B
(5)
I
where I0 and I are the PL intensities in the absence and pres-
ence of PA, respectively, and Vq is the static quenching constant
in unit of L mol−1.[19] By fitting the Stern–Volmer plots shown
in Figure 9c, Equations 2, 3, and 4 are obtained for TPTPE,
TPTDPE, and BTPTPE in aqueous mixtures with 90% water
contents, respectively.
If we conservatively neglect these two terms, the k value in
Equation 5 becomes the static quenching constants, equal
to 46157, 37029, and 61708 L mol−1 for TPTPE, TPTDPE,
and BTPTPE, respectively. These values are much higher
than those (1–185 L mol−1) of linear iptycene-containing
a) 450
6
b)
104
103
102
101
100
5
4
3
2
1
360
270
180
90
380
460
540
620
700
Wavelength (nm)
0
0
5
7
9
11
13
15
0
50
100 150 200
Current density(mA/cm2)
250
300
Voltage (V)
Figure 8. Changes in a) current density and luminance with the applied voltage and b) current efficiency with the current density in a multilayer light-
emitting diode of TPTPE with a device configuration of ITO/NPB/TPTPE/TPBi/LiF/Al. Inset: EL spectrum of TPTPE.
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Table 3. EL performances of TPTPE, TPTDPE, and BTPTPE. With a
device configuration of ITO/NPB/LEL/TPBi/LiF/Al. Abbreviations: LEL =
light-emitting layer, λEL = electroluminescence maximum, Von = turn-on
voltage at 1 cd m−2, Lmax = maximum luminance, ηP = maximum power
efficiency, ηC = maximum current efficiency, and ηext = maximum external
quantum efficiency.
I0
I
= A(1 + k[PA]) + B = Ak[PA] + A + B = K [PA] + C
(7)
Thus, the static quenching constants (K) for TPTPE,
TPTDPE, and BTPTPE at the initial stage of the Stern–
Volmer plots are 64620, 105533, and 66645 L mol−1,
respectively, which are much higher than those
(K < 20000 L mol−1) of the fluorescent chemosensors based
on linear polysiloles.[21]
No.
LEL
Von
[V]
Lmax
[cd m−2
λEL
[nm]
ηP
ηC
ηext
[%]
[lm W−1
]
[cd A−1
]
]
1
2
3
TPTPE
TPTDPE
BTPTPE
488
512
448
4.2
4.2
5.2
10800
7620
3530
3.5
2.2
1.4
5.8
3.0
2.8
2.7
1.1
1.6
Generally, intrinsic autoaggregation and/or analyte-
induced aggregation cause self-quenching problems that
greatly reduce the sensing performance. However, aggrega-
tion is beneficial to the PL of the dye molecules. The PA
molecules in the inner cores and on the outer shells of the
aggregates work cooperatively to facilitate PL annihilation
through electron and/or energy transfers, thus making the
emission quenching a highly efficient process. By plotting
the relative PL intensity versus ek[PA], linear relationships
are obtained (Figure 9d), which enable quantitative analysis.
We are now fabricating thin-film-based chemosensors
and examining their sensitivity and selectivity to various
explosives.
poly(p-phenylenebutadiynylene)s and poly(p-phenyleneethyny-
lene)s, widely investigated fluorescent polymers for explo-
sive detection.[20] At low quencher concentrations ([PA]→0),
Equation 5 is readily converted to Equation 6 by a mathematical
treatment of the Taylor expansion, which can be reorganized to
give Equation 7 where K = Ak, C = A + B = 1.
I0
I
1
kn[PA]n
n!
= A(1 + k[PA] + k2[PA]2 + · · · +
+ · · ·) + B
(6)
2
b)
a)
PA conc (µg/mL)
PA conc (µg/mL)
0
0
12
13
370
420
470
520
570
620
370
420
470
520
570
620
Wavelength (nm)
Wavelength (nm)
c) 30
d) 30
OH
O2N
NO2
24
18
12
6
24
18
12
6
NO2
Picric acid (PA)
TPTPE
TPTDPE
BTPTPE
TPTPE
TPTDPE
BTPTPE
0
0
0
12
24
36
48
60
0
5
10
15
20
25
30
µ
PA conc( M)
ek[PA ]
Figure 9. PL spectra of a) TPTPE and b) BTPTPE in THF/H2O mixtures (1:9 by volume) containing different amounts of picric acid (PA). Concentra-
tion: 10−5 m; excitation wavelength: 330 nm. Plots of relative PL intensities (I0/I) versus c) PA concentrations, and d) ek[PA] values of TPTPE, TPTDPE,
and BTPTPE in THF/H2O mixtures (1:9 by volume). I0 = intensity at [PA] = 0 μm.
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30
24
18
12
6
a)
b) 32
c)
Ru3+ conc (µM)
24
0
TPTPE
TPTDPE
BTPTPE
TPTPE
TPTDPE
20
16
8
0
0
380
430
480
530
580
630
0
7
14
21
0
5
10
15
20
25
ek[Ru3+]
Ru3+ conc(µM)
Wavelength (nm)
Figure 10. a) PL spectra of TPTPE in THF/H2O mixtures (1:9 by volume) with varied Ru3+ concentrations. Plots of relative PL intensities (I0/I) versus
b) Ru3+ concentrations and c) ek[Ru3+] values of TPTPE, TPTDPE, and BTPTPE in THF/H2O mixtures (1:9 by volume). I0 = intensity at [Ru3+] = 0 μm.
2.6. Metal-Ion Sensors
example (Figure S3 in the Supporting Information). The life-
time of TPTPE in 90% aqueous mixture remains unchanged
when different amounts of Ru3+ are added, which suggests
that the PL quenching process operates through the static
mechanism. As a result, we obtained the following equations
(Equations 8 and 9) for TPTPE and TPTDPE:
The development of highly selective sensors for metal ions is
particularly important because metal ions can have detrimental
effects on human and the environment. Ruthenium(III) com-
plexes are used widely as catalysts in oxidation and metathesis
reactions, but they are corrosive and destructive to the respira-
tory tract, eyes, skin, and digestive tract. They are regarded as
a risk to aquatic organisms and may cause long-term adverse
effects on the aquatic environment. Thus, the monitoring of
ruthenium(III) ion, one of the most common and stable forms
of ruthenium, is becoming an important issue. However, rati-
ometric fluorescent probes for Ru3+ are rare at present. Thus,
we investigated whether the present luminogens can serve as
sensitive and selective fluorescent chemosenors for Ru3+ ion
detection.
I0
= 0.47e199868[PA] + 0.99
I
(8)
I0
I
= 6.98e86495[PA] − 7.36
(9)
Similar to the case for explosive detection, the k values for
TPTPE and TPTDPE are 199868 and 86495 L mol−1, respec-
tively, if we neglect the two constants as in Equation 5. When
the Ru3+ concentration is very low, the static quenching con-
stants (K) at the initial stage of the Stern–Volmer plots become
94390 and 603785 L mol−1, respectively.
With the gradual addition of Ru3+ ion to the nanoparticle
suspensions of the luminogens in THF/H2O mixtures
(1:9 by volume), the emissions of TPTPE, TPTDPE, and BTPTPE
decrease progressively (Figure 10). The PL quenching can be
clearly recognized at a low Ru3+ concentration of 1 μg mL−1. At
[Ru3+] = 20 μm, the PL intensity of BTPTPE is merely ~30% of
its original value. At the same ion concentration, in contrast,
the emissions of TPTPE and TPTDPE are almost quenched
completely, showing a 10-fold higher sensitivity. The Stern–
Volmer plots of I0/I values versus Ru3+ concentrations for
TPTPE and TPTDPE give exponential growth curves similar
to those in Figure 9c, which indicates that the PL quenching
process is more efficient at higher quencher concentration.
TPTPE, TPTDPE, and BTPTPE are considered to be electron-
rich, while Ru3+ is electron-deficient. Thus, electrostatic interac-
tion or charge-transfer complexation may play an important
role for the PL annihilation. As mentioned previously, in the
static quenching model, the luminogenic molecules that bind
to the quencher molecules are in the nonemissive or “dark”
state, while the unbound molecules exhibit their intrinsic life-
times. Thus, we measured the lifetimes of the luminogens in
the absence and presence of quencher to check whether the
same mechanism operates for the metal-ion-caused emission
quenching. TPTPE in the aggregate state was chosen as an
To evaluate whether Ru3+ detection is selective, we studied
the PL change of the luminogens in the presence of other metal
ions. As shown in Figure 11, addition of other metal ions,
including Mg2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Rh3+, Ag+,
and Cd2+, exerts little change on the PL of TPTPE, TPTDPE,
and BTPTPE, which indicates the high selectivity of the three
luminogens towards Ru3+. Although the reason for such selec-
tivity remains unclear at present, we believe that the higher
standard reduction potential of the Ru(III)/Ru(0) couple rela-
tive to other cation/metal systems may be responsible for such
selective sensing.
3. Conclusion
We have designed and synthesized a group of benzene-cored
luminogens with multiple triarylvinyl peripheries. All the
luminogens were weakly emissive in solution but became
strong emitters when aggregated in the condensed phase,
which is demonstrative of the novel phenomenon of AIE. The
benzene-cored luminogens exhibit high solid-state fluorescence
quantum yields and enjoy high thermal and morphological
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4.5
9.0
7.5
6.0
4.5
3.0
1.5
0.0
3.5
2.8
2.1
1.4
0.7
0.0
a)
b)
c)
TPTDPE
BTPTPE
TPTPE
3.6
2.7
1.8
0.9
0.0
Mg2+
Fe3+
Ni2+
Zn2+
Cu2+
Metal ion
Rh3+
Ru3+
Cd2+
Ag+
Mg2+
Fe3+
Ni2+
Cu2+
Metal ion
Zn2+
Rh3+
Ag+
Cd2+
Mg2+
Fe3+
Ni2+
Zn2+
Ru3+
Rh3+
Cd2+
Fe2+
Co2+
Fe2+
Co2+
Ru3+
Fe2+
Co2+
Cu2+
Ag+
Metal ion
Figure 11. Changes in relative PL intensities (I0/I) of a) TPTPE, b) TPTDPE, and c) BTPTPE in THF/H2O mixtures (1:9 by volume; 10 μm) with various
metal ions (2 mm). I0 = intensity in the absence of metal ions.
I = A1e−t τ + A2 e −t τ
stabilities. OLEDs using TPTPE, TPTDPE, and BTPTPE as emit-
ters were fabricated, and show high luminance and current and
external quantum efficiencies; up to 10800 cd m−2, 5.8 cd A−1,
and 2.7%, respectively. The luminogen emissions could be
quenched efficiently by PA and Ru3+ with large quenching
constants, which renders the luminogens promising as chemo-
sensors for explosives and metal ions.
/
/
1
2
(10)
where τ1 and τ2 are the lifetimes of the shorter- and longer-lived species,
respectively, and A1 and A2 are their respective amplitudes. The weighted
mean lifetime <t> was calculated according to Equation 11:
<τ> = (A1τ1 + A2τ2)/ (A1 + A2)
(11)
Device Fabrication: The devices were fabricated on 80 nm ITO coated
glasses with a sheet resistance of 25 Ω −1. Prior to loading into the
pretreatment chamber, the ITO-coated glasses were soaked in ultrasonic
detergent for 30 min, followed by spraying with deionized water for
10 min, soaking in ultrasonic deionized water for 30 min, and oven baking
for 1 h. The cleaned samples were treated by perfluoromethane plasma
with a power of 100 W, a gas flow of 50 sccm, and a pressure of 0.2 Torr
for 10 s in the pretreatment chamber. The samples were transferred
to the organic chamber with a base pressure of 7 × 10−7 Torr for the
deposition of NPB, emitter, and TPBi, which served as hole-transport,
light-emitting, hole-blocking, and electron-transport layers, respectively.
The samples were then transferred to the metal chamber for cathode
deposition, which was composed of LiF capped with Al. The light-
emitting area was 4 mm2. The current density–voltage characteristics
of the devices were measured by a HP4145B semiconductor parameter
analyzer. The forward direction photons emitted from the devices were
detected by a calibrated UDT PIN-25D silicon photodiode. The luminance
and external quantum efficiencies of the devices were inferred from
the photocurrent of the photodiode. The electroluminescence spectra
were obtained by a PR650 spectrophotometer. All measurements were
carried out under air at room temperature without device encapsulation.
Preparation of Nanoaggregates: Stock THF solutions of the
luminogens were prepared with a concentration of 10−3 m. Aliquots of
the stock solution were transferred to 10 mL volumetric flasks. After
appropriate amounts of THF were added, water was added dropwise
under vigorous stirring to furnish 10−5 m solutions with various water
contents (0–95 vol%). PL measurements of the resulting solutions were
then performed immediately.
4. Experimental Section
Materials and Instrumentation: DCM and THF were distilled under
nitrogen from calcium hydride and sodium benzophenone ketyl,
respectively, immediately prior to use. All chemicals were purchased from
1
Aldrich and used as received. H and 13C NMR spectra were measured
on a Bruker AV 300 spectrometer in deuterated chloroform using
tetramethylsilane (TMS; δ = 0) as internal reference. High-resolution
mass spectra (HRMS) were recorded on a GCT premier CAB048 mass
spectrometer operating in MALDI-TOF mode. UV spectra were measured
on a Milton Roy Spectronic 3000 Array spectrophotometer. PL was
recorded on a Perkin-Elmer LS 55 spectrofluorometer. TGA was carried
on a TA TGA Q5000 under nitrogen at a heating rate of 10 °C min−1.
Thermal transitions of the luminogens were investigated by DSC using a
TA DSC Q1000 under dry nitrogen at a heating rate of 10 °C min−1. TEM
images and electron diffraction patterns were taken on a JEOL 100CX
TEM instrument. Particle sizes of the aggregates in THF/water mixtures
were measured on a BeCoulter Delsa 440SX Zeta potential analyzer.
Single-crystal X-ray diffraction data were collected at 100 K on a Bruker–
Nonices Smart Apex CCD diffractometer with graphite monochromated
Mo Kα radiation. Processing of the intensity data was carried out using
the SAINT and SADABS routines, and the structure and refinement were
conducted using the SHELXL suite of X-ray programs (version 6.10). The
ground-state geometries were optimized using the density functional
(DFT) with B3LYP hybrid functional at the basis-set level of 6-31G*.
All calculations were performed using the Gaussian 03 package. Time-
resolved PL spectra were measured by using a Hamamatsu model C4334
streak camera coupled to a spectrometer. A femtosecond titanium-
sapphire oscillator was used as the excitation source. A UV beam with
a wavelength of 267 nm (third harmonic of the laser output at 800 nm)
was used as the pumping source in the experiments. Pulse width and
repetition rate of the laser were 200 fs and 76 MHz, respectively.
Excitation power was about 0.3 mW. The time resolution was 20 ps. The
PL signals were measured at 380 nm. The decay in the PL intensity (I)
with time (t) was fitted by a double-exponential function (Equation 10):
Preparation of Metal-Ion Solutions: Inorganic salts (magnesium
chloride, iron(II) chloride, iron(III) chloride, cobalt(II) chloride, nickel(II)
chloride, copper(II) chloride, zinc chloride, ruthenium(III) chloride,
rhodium(III) chloride, silver chloride, and cadmium chloride) were
dissolved in distilled water (10 mL) to afford 10 mm aqueous solutions.
The stock solutions were diluted to the desired concentrations with
distilled water for further experiments.
Synthesis of 1,4-Phenylene Bis(phenylmethanone) (2): Terephthaloyl
chloride (1, 8 g, 39.4 mmol), aluminium chloride (26.3 g, 197.0 mmol),
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and benzene (40 mL) were added to a 100 mL one-necked round-
bottomed flask. The reaction mixture was heated under reflux for 24 h.
A large amount of cold water was added to quench the reaction and the
reaction mixture was then extracted with DCM. The organic layer was
washed with water and dried over magnesium sulfate. After filtration and
solvent evaporation, the crude product was purified by silica-gel column
chromatography using hexane/DCM (3:2 by volume) as eluent. The
Supporting Information
Supporting Information is available from the Wiley Online Library or
from the author.
1
Acknowledgements
product 2 was obtained as a white solid (6.4 g; 56.7% yield). H NMR
(400 MHz, CDCl3), δ (ppm): 7.89 (s, 4H), 7.84 (d, 4H), 7.63 (t, 4H), 7.51
(t, 4H). 13C NMR (75 MHz, CDCl3), δ (ppm): 196.71, 141.32, 137.61,
133.65, 130.80, 130.40, 129.16. HRMS (MALDI-TOF): m/z 286.1020 [M+,
calcd 288.0994].
Synthesis of 1,4-Phenylene Bis(2-thienylmethanone) (3): Compound 3
was synthesized from 1 (5 g, 24.6 mmol), aluminium chloride (16.4 g,
123.1 mmol), and thiophene (5.2 g, 61.6 mmol), in freshly distilled
DCM (50 mL) at room temperature. The procedure was similar to that
described above, and afforded the product as a grey solid (4.2 g; yield
57.4%). 1H NMR (300 MHz, CDCl3), δ (ppm): 7.97 (s, 4H), 7.87 (d, 2H),
7.68 (d, 2H), 7.20 (t, 2H). 13C NMR (75 MHz, CDCl3), δ (ppm): 188.19,
143.89, 141.80, 135.97, 135.70, 129.77, 128.91. HRMS (MALDI-TOF):
m/z 299.0799 [(M+1)+, calcd 299.0122].
This work was partially supported by the Research Project Competition
of HKUST (RPC11SC09 and RPC10SC13), the Research Grants Council
of Hong Kong (604711, 603509, and HKUST2/CRF/10), the National
Natural Science Foundation of China (20634020 and 20974028), and
the University Grants Committee of Hong Kong (AoE/P-03/08). B.Z.T.
acknowledges support from the Cao Guangbiao Foundation of Zhejiang
University.
Received: August 23, 2011
Published online: November 14, 2011
[1] a) A. P. DeSilva, H. Q. N. Gunaratne, T. Gunnlaugsson, A. J. M. Huxley,
C. P. McCoy, J. T. Rademacher, T. E. Rice, Chem. Rev. 1997, 97,
1515; b) W. P. Ambrose, P. M. Goodwin, J. H. Jett, A. Van Orden,
J. H. Werner, R. A. Keller, Chem. Rev. 1999, 99, 2929; c) W. F. Patton,
Biotechniques 2000, 28, 944.
[2] a) C.-T. Chen, Chem. Mater. 2004, 16, 4389; b) U. Lemmer, S. Heun,
R. F. Mahrt, U. Scherf, M. Hopmeier, U. Siegner, E. O. Gobel,
K. Müllen, H. Bassler, Chem. Phys. Lett. 1995, 240, 373.
[3] a) I. L. Medintz, H. T. Uyeda, E. R. Goldman, H. Mattoussi, Nat.
Mater. 2005, 4, 435; b) M. De, P. S. Ghosh, V. M. Rotello, Adv.
Mater. 2008, 20, 4225.
[4] a) J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S. Kwok,
X. Zhan, Y. Liu, D. Zhu, B. Z. Tang, Chem. Commun. 2001, 1740;
b) B. Z. Tang, X. Zhan, G. Yu, P. P. S. Lee, Y. Liu, D. Zhu, J. Mater.
Chem. 2001, 11, 2974.
[5] a) Y. Hong, J. W. Y. Lam, B. Z. Tang, Chem. Soc. Rev. 2010, 39, in
press; b) Z. Zhao, J. W. Y. Lam, B. Z. Tang, Curr. Org. Chem. 2010,
14, 2109; c) J. Liu, J. W. Y. Lam, B. Z. Tang, J. Inorg. Organomet.
Polym. Mater. 2009, 19, 249; d) Y. Hong, J. W. Y. Lam, B. Z. Tang,
Chem. Commun. 2009, 4332.
[6] C. J. Bhongale, C. W. Chang, C. S. Lee, E. W. G. Diau, C. S. Hsu,
J. Phys. Chem. B. 2005, 109, 13472.
[7] Y. T. Wu, M. Y. Kuo, Y. T. Chang, C. C. Shin, T. C. Wu,
C. C. Tai, T. H. Cheng, W. S. Liu, Angew. Chem. Int. Ed. 2008, 47,
9891.
[8] C. X. Yuan, X. T. Tao,L. Wang, J. X. Yang, M. H. Jiang, J. Phys. Chem.
C. 2009, 113, 6809.
[9] G. Qian, B. Dai, M. Luo, D. Yu, J. Zhan, Z. Zhang, M. Dongge,
Z. Y. Wang, Chem. Mater. 2008, 20, 6208.
Synthesis of 1,3,5-Benzenetris(phenylmethanone) (5): Compound 5 was
prepared from 1,3,5-benzenetricarbonyl trichloride (4, 4 g, 15.1 mmol),
aluminium chloride (15.1 g, 113.0 mmol), and benzene (40 mL). The
procedure was similar to that used for the synthesis of 2, and gave the
product as a white solid (5.3 g; yield 90.6%). 1H NMR (300 MHz, CDCl3),
δ (ppm): 8.40 (s, 3H), 7.85 (d, 6H), 7.64 (t, 3H), 7.50 (t, 6H). 13C NMR
(75 MHz, CDCl3), δ (ppm): 195.62, 138.90, 137.13, 134.80, 133.98, 130.80,
129.36. HRMS (MALDI-TOF): m/z 391.1150 [(M+1)+, calcd 391.1256].
Synthesis of 1-[4-(1,2,2-Triphenylvinyl)phenyl]-1,2,2-triphenylethene
(TPTPE): n-Butyllithium solution (2.5 M in hexane; 8.0 mmol) was added
to a solution of diphenylmethane (1.34 g, 8.0 mmol) in dry THF (40 mL)
at 0 °C under nitrogen. The resultant orange–red solution containing 4
was stirred at 0 °C for 2 h before 2 (3.5 mmol) was added. The reaction
mixture was allowed to warm to room temperature and was then stirred
for a further 6 h. The reaction was quenched by adding an aqueous
solution of ammonium chloride. The organic layer was extracted three
times with DCM. The organic layers were combined, washed with water,
and dried over anhydrous magnesium sulfate. After solvent evaporation,
the crude alcohol (containing excess diphenylmethane) was dissolved in
about 50 mL of toluene in a 100 mL two-necked round bottomed flask
equipped with a condenser. A catalytic amount of p-toluenesulfonic acid
was then added and the mixture was then heated to reflux. After cooling
to room temperature, the organic layer was washed twice with aqueous
NaHCO3 solution (25 mL; 10%) and dried over anhydrous magnesium
sulfate. After solvent evaporation, the crude product was purified by
silica-gel column chromatography using hexane/DCM (4:1 v/v) as
eluent to afford the product as a white solid (0.8 g; yield 38.2%). 1H
NMR (300 MHz, CDCl3), δ (ppm): 7.15–7.09 (m, 20H), 7.03–7.02 (m,
10H), 6.79 (s, 4H). 13C NMR (75 MHz, CDCl3), δ (ppm): 144.43, 144.40
144.19, 142.55, 141.48, 132.05, 132.00, 131.32, 128.28, 128.21, 127.11,
127.03. HRMS (MALDI-TOF): m/z 586.3777 [M+, calcd 586.2661].
TPTDPE and BTPTPE were prepared by similar synthetic procedures
and their characterization data are given below:
[10] K. Kokado, Y. Chujo, Macromolecules 2009, 42, 1418.
[11] a) Q. Zhao, L. Li, F. Li, M. Yu, Z. Liu, T. Yi, C. Huang, Chem. Commun.
2008, 685; b) Y. You, H. S. Huh, K. S. Kim, S. W. Lee, D. Kim,
S. Y. Park, Chem. Commun. 2008, 3998.
1-{4-[1-(2-Thienyl)-2,2-diphenylvinyl]phenyl}-1-(2-thienyl)-2,2-
diphenylethene (TPTDPE): White Solid; yield 0.4 g, 21.2%. 1H NMR
(300 MHz, CDCl3), δ (ppm): 7.24–7.16 (m, 9H), 7.12–7.07 (m, 9H),
6.97 (d, 8H), 6.76 (t, 2H), 6.51 (d, 2H). 13C NMR (75 MHz, CDCl3), δ
(ppm): 146.30, 143.64, 143.20, 141.94, 141.04, 133.77, 131.12, 130.97,
130.82, 129.63, 128.32, 127.62, 127.19, 126.53, 126.24, 126.07. HRMS
(MALDI-TOF): m/z 598.3684 [M+, calcd 598.1789].
[12] a) H. Chen, J. W. Y. Lam, J. Luo, Y. Ho, B. Z. Tang, D. Zhu, M. Wong,
H. S. Kwok, Appl. Phys. Lett. 2002, 81, 574; b) Y. Cao, I. D. Parker,
G. Yu, C. Zhang, A. J. Heeger, Nature 1999, 397, 414; c) J. S. Kim,
P. K. Ho, N. C. Greenham, R. H. Friend, J. Appl. Phys. 2000, 88,
1073; d) S. Chen, Z. Zhao, B. Z. Tang, H. S. Kwok, J. Phys. D: Appl.
Phys. 2010, 43, 095101; e) Z. Zhao, C. Deng, S. Chen, J. W. Y. Lam,
W. Qin, P. Lu, Z. Wang, H. S. Kwok, Y. Ma, H. Qiu, B. Z. Tang, Chem.
Commun. 2011, 47, 8847; f) Y. Liu, S. Chen, J. W. Y. Lam, P. Lu,
R. T. K. Kwok, F. Mahtab, H. S. Kwok, B. Z. Tang, Chem. Mater.
2011, 23, 2536; g) Z. Zhao, S. Chen, J. W. Y. Lam, Z. Wang, P. Lu,
F. Mahtab, H. H. Y. Sung, I. D. Williams, Y. Ma, H. S. Kwok,
B. Z. Tang, J. Mater. Chem. 2011, 21, 7210; h) W. Z. Yuan, P. Lu,
1-[3,5-Bis(1,2,2-triphenylvinyl)phenyl]-1,2,2-triphenylethene (BTPTPE):
1
White solid; yield 0.7 g, 24.4%. H NMR (300 MHz, CDCl3), δ (ppm):
7.18 (t, 9H), 7.03 (d, 18H), 6.90 (t, 6H), 6.84 (t, 6H), 6.62 (t, 6H), 6.49
(s, 3H). 13C NMR (75 MHz, CDCl3), δ (ppm): 144.36, 144.24, 143.85,
143.49, 141.32, 140.89, 132.75, 132.08, 131.83, 131.62, 128.27, 128.13,
127.95, 127.03, 126.80. HRMS (MALDI-TOF): m/z 840.1480 [M+, calcd
840.3756].
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388 wileyonlinelibrary.com
2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Funct. Mater. 2012, 22, 378–389

www.afm-journal.de
www.MaterialsViews.com
S. Chen, J. W. Y. Lam, Z. Wang, Y. Liu, H. S. Kowk, Y. Ma, B. Z. Tang,
Adv. Mater. 2010, 22, 2159.
Chem. Commun. 2007, 40; c) H. Tong, Y. Q. Dong, M. Häußler,
J. W. Y. Lam, H. H.-Y. Sung, I. D. Williams, J. Sun, B. Z. Tang, Chem.
Commun. 2006, 1133.
[13] a) Y. Yu, C. Feng, Y. Hong, J. Liu, S. Chen, K. M. Ng, K. Q. Luo,
B. Z. Tang, Adv. Mater. 2011, 23, 3298; b) M. Wang, G. Zhang,
D. Zhang, D. Zhu, B. Z. Tang, J. Mater. Chem. 2010, 20, 1858;
c) T. Sanji, K. Shiraishi, M. Tanaka, ACS Appl. Mater. Interf. 2009, 1,
270; d) Y. Liu, C. Deng, L. Tang, A. Qin, R. Hu, J. Z. Sun, B. Z. Tang,
J. Am. Chem. Soc. 2011, 133, 660; e) Y. Liu, Y. Tang, N. N. Barashkov,
I. S. Irgibaeva, J. W. Y. Lam, R. Hu, D. Birimzhanova, Y. Yu,
B.Z.Tang,J.Am.Chem.Soc.2010,132,13951;f)Y.Hong,C.Feng,Y.Yu,
J. Liu, J. W. Y. Lam, K. Q. Luo, B. Z. Tang, Anal. Chem. 2010, 82, 7035;
g) Y. Hong, H. Xiong, J. W. Y. Lam, M. Häuβler, J. Liu, Y. Yu, Y. Zhong,
H. H. Y. Sung, I. D. Williams, K. S. Wong, B. Z. Tang, Chem. Eur. J.
2010, 16, 1232.
[17] a) Y. Liu, R. C. Mills, J. M. Boncella, K. S. Schanze, Langmuir 2001,
17, 7452; b) T. H. Kim, H. J. Kim, C. G. Kwak, W. H. Park, T. S. Lee,
J. Polym. Sci. Part A: Polym. Chem. 2006, 44, 2059; c) J. C. Sanchez,
W. C Trogler, J. Mater. Chem. 2008, 18, 3143; d) T. Naddo, Y. Che,
W. Zhang, K. Balakrishnan, X. Yang, M. Yen, J. Zhao, J. S. Moore,
L. Zhang, J. Am. Chem. Soc. 2007, 129, 6978; e) M. E. Germain,
M. J. Knapp, J. Am. Chem. Soc. 2008, 130, 5422; f) A. D. Hughes,
I. C. Glenn, A. D. Patrick, A. Ellington, E. V. Anslyn, Chem. Eur. J.
2008, 14, 1822; g) Y. Jiang, H. Zhao, N. Zhu, Y. Lin, P. Yu, L. Mao,
Angew. Chem. Int. Ed. 2008, 47, 8601; h) Y. Long, H. Chen, Y. Yang,
H. Wang, Y. Yang, N. Li, K. Li, J. Pei, F. Liu, Macromolecules 2009,
42, 6501.
[18] a) J. Liu, Y. Zhong, P. Lu, Y. Hong, J. W. Y. Lam, M. Faisal, Y. Yu,
K. S. Wong, B. Z. Tang, Polym. Chem. 2010, 1, 426; b) P. Lu,
J. W. Y. Lam, J. Liu, C. K. W. Jim, W. Yuan, N. Xie, Y. Zhong, Q. Hu,
K. S. Wong, K. K. L. Cheuk, B. Z. Tang, Macromol. Rapid Commun.
2010, 31, 834.
[14] W. Wang, T. Lin, M. Wang, T.-X. Liu, L. Ren, D. Chen, S. Huang,
J. Phys. Chem. B. 2011, 114, 5983.
[15] a) Z. Li, Y. Dong, B. Mi, Y. Tang, M. Häuβler, H. Tong, Y. Dong,
J. W. Y. Lam, Y. Ren, H. H. Y. Sun, K. S. Wong, P. Gao,
I. D. Williams, H. S. Kwok, B. Z. Tang, J. Phys. Chem. B 2005, 109,
10061; b) S. Dong, Z. Li, J. Qin, J. Phys. Chem. B 2009, 113, 434;
c) G. Yu, S. Yin, Y. Liu, J. Chen, X. Xu, X. Sun, D. Ma, X. Zhan,
Q. Peng, Z. Shuai, B. Z. Tang, D. Zhu, W. Fang, Y. Luo, J. Am. Chem.
Soc. 2005, 127, 6335.
[16] a) X. Luo, J. Li, C. Li, Y. Q. Dong, Z. Liu, Z. Bo, B. Z. Tang, Adv.
Mater. 2011, 23, 3261; b) Y. Dong, J. W. Y. Lam, A. Qin, J. Sun, J. Liu,
Z. Li, J. Sun, H. H. Y. Sung, I. D. Williams, H. S. Kwok, B. Z. Tang,
[19] B. Valeur, Molecular Fluorescence: Principle and Applications; Wiley-
VCH: Weinheim, Germany 2002.
[20] D. Zhao, T. M. Swager, Macromolecules 2005, 38, 9377.
[21] a) J. C. Sanchez, A. G. DiPasquale, A. L. Rheingold, W. C. Trogler,
Chem. Mater. 2007, 19, 6459; b) H. Sohn, M. J. Sailor, D. Magde,
W. C. Trogler, J. Am. Chem. Soc. 2003, 125, 3821.
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Adv. Funct. Mater. 2012, 22, 378–389
2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
389