Starburst dendrimers consisting of triphenylamine core and 9-phenylcarbazole-based dendrons: Synthesis and properties

Article abstract of DOI:10.1039/c2ob26483h

Novel dendrimers consisting of a triphenylamine core and 1st to 3rd generations of 9-phenylcarbazole-based dendrons were synthesized by Suzuki coupling reaction through convergent approach. Their structures were confirmed by two-dimensional correlated H-H COSY and C-H HSQC NMR spectra, MALDI-TOF MS and elemental analysis. The dendrimers exhibit excellent thermal stability with 5% weight loss temperatures over 540 °C. The computer modeling reveals that the dendrons in dendrimers greatly twisted with the generation, leading to the dendrimers decreased crystalline ability. Of interest is the observation that, for an identical dendrimer, the solid film displays the similar UV absorption and luminescence emission profiles to the solution sample, indicating that, after evaporation of solvent, the rigid dendrimer can well maintain its conformational morphology and the aggregation or stacking of the chromophoric groups is significantly inhibited. All the dendrimers can emit intense fluorescence with narrow full width at half maximum (FWHM) around 46-50 nm. Moreover, with the incremental generation, the quantum efficiencies remarkably increase from 64 to 95%, suggesting that the highly contorted and bulky dendrons effectively decrease energy wastage and non-radiative decay. The synergistic effect of electron-donating triphenylamine core and 9-phenylcarbazole-based dendrons results in the HOMO energy level of -5.36 eV for the 3rd-generation dendrimer, very close to the work function of the ITO/PEDOT electrode (-5.2 eV), which characteristic is very advantageous for the hole injection and transport materials.

Full text of DOI:10.1039/c2ob26483h

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Starburst dendrimers consisting of triphenylamine
core and 9-phenylcarbazole-based dendrons:
synthesis and property
Jia You, Guiyang Li and Zhonggang Wang∗
State Key Laboratory of Fine Chemicals, Department of Polymer Science and Materials, School of
Chemical Engineering. Dalian University of Technology, Dalian 116023, P. R. China
∗
To whom all correspondences should be addressed.
Email: zgwang@dlut.edu.cn

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ABSTRACT: Novel dendrimers consisting of a triphenylamine core and 1st to 3rd generations of 9ꢀ
phenylcarbazoleꢀbased dendrons were synthesized by Suzuki coupling reaction through convergent
approach. Their structures were confirmed by twoꢀdimensional correlated HꢀH COSY and CꢀH HSQC
NMR spectra, MALDIꢀTOF MS and elemental analysis. The dendrimers exhibit excellent thermal
stability with 5% weight loss temperatures over 540 °C. The computer modeling reveals that the
dendrons in dendrimers greatly twisted with the generation, leading to the dendrimers decreased
crystalline ability. Of interest is the observation that, for an identical dendrimer, the solid film displays
the similar UV absorption and luminescence emission profiles to the solution sample, indicating that,
after evaporation of solvent, the rigid dendrimer can well maintain its conformational morphology and
the aggregation or stacking of the chromophoric groups is significantly inhibited. All the dendrimers
can emit intense fluorescence with narrow full width at half maximum (FWHM) around 46ꢀ50 nm.
Moreover, with the incremental generation, the quantum efficiencies remarkably increase from 64 to
95%, suggesting that the highly contorted and bulky dendrons effectively decrease energy wastage and
nonradiative decay. The synergistic effect of electronꢀdonating triphenylamine core and 9ꢀ
phenylcarbazoleꢀbased dendrons results in the HOMO energy level of ꢀ5.36 eV for the 3rdꢀgeneration
dendrimer, very close to the work function of the ITO/PEDOT electrode (ꢀ5.2 eV), which characteristic
is very advantageous for the hole injection and transport materials.
Keywords: dendrimers, triphenylamine, carbazole, synthesis, optoelectronic property
Introduction
Dendrimers are threeꢀdimensional treelike molecules possessing wellꢀdefined structures composed of a
core and various numbers of dendrons. The synthesis method of dendrimers by stepwise generationꢀbyꢀ
generation growth ensures the batch to batch reproducibility, definite chemical structure, molecular
weight and monodispersity.1 These characteristics endow dendrimers with distinct physicochemical
nature from linear and hyperbranched polymers in numerous aspects such as interꢀmolecular

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aggregation, crystalline behavior, solubility and filmꢀforming process. Dendrimers have found a wide
range of applications, including drug delivery systems,2 magnetic resonance imaging,3 homogeneous
catalysis4 and optical data storage.5 Recently, they have also been exploited as an active component for
electronics and optoelectronics molecular devices6 such as organic lightꢀemitting diodes (OLEDs)7
since the dendritic topology can effectively suppress the formation of excimers8 and enhance the charge
transport ability.9
The properties of a dendrimer are tightly correlated with the chemical structure of the core, dendrons
and generation number. Carbazole possesses strong absorption in nearꢀUV region, low redox
potential,10 intense luminescence emission,11 and outstanding holeꢀtransporting ability.12 Moreover,
carbazole can be easily functionalized at its 3ꢀ, 6ꢀ, and 9ꢀ position, thus conveniently covalentꢀlinked to
other molecular moieties.13 Several attempts to prepare carbazoleꢀbased polymers have been
conducted, which reveal and some interesting properties such as efficient energy harvest and transfer.14
For example, the dendrimer with carbazoleꢀbased monodendrons synthesized by Zhao and coꢀworkers
displays stable green electroluminescent emission.15 Zhang and coworkers also demonstrate that the
dendrimer consisting of carbazoleꢀbased dendrons and the heterotriangulene cores have highly efficient
energy transfer.16
The present work was undertaken to design and synthesize novel dendrimers consisting of 9ꢀ
phenylcarbazoleꢀbased dendrons and triphenylamine core with precisely controlled generation of
dendrons, in which the electronꢀrich triphenylamine was chosen as core because of its high pꢀtype
charge transport mobility and low ionization potential.17 The bulky and twisted dendrons afford the
dendrimer high steric hindrance which effectively inhibits the close molecular packing. Moreover, the
large distortion angle of carbazoleꢀbased dendrons with respect to the triphenylamine core will interrupt
the delocalization of πꢀelectrons within the dendrimer so that the high triplet energy transition between
carbazole and triphenylamine in the dendrimers is unperturbed, and the extent can be tuned through
changing the generation. The effects of systematical variations of chemical and topological structures

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on thermal stability, photophysical and electrochemical properties of dendrimers of different generation
numbers, e.g., quantum efficiencies, charge transports and HOMOꢀLUMO energy band gaps, will be
investigated and discussed in detail.
Results and Discussion
Synthesis and characterization
The synthesis routes of 1stꢀ3rd generations of dendrons, GnꢀB(OH)2 (n = 1, 2, 3) are outlined in
Scheme 1. 9ꢀ(4ꢀBromophenyl)carbazole G1ꢀBr (1) was synthesized from carbazole and 1,4ꢀ
dibromobenzene by Ullmann coupling reaction. Iodination of G1ꢀBr (1) at the 3, 6ꢀpositions using
potassium iodide and potassium iodate in boiling glacial acetic acid led to diiodide (2) in good yield.
The obtained G1ꢀBr (1) was further reacted with nꢀBuLi in THF at ꢀ78 °C, followed by the addition of
triisopropyl borate, and hydrolysis with 2N HCl to give the corresponding 1stꢀgeneration dendron G1ꢀ
B(OH)2 (3). The Suzuki coupling of G1ꢀB(OH)2 (3) and (2) in the presence of
tetrakis(triphenylphosphine) palladium and K2CO3 gave G2ꢀBr (4), which was then converted into the
corresponding 2ndꢀgeneration dendron G2ꢀB(OH)2. Similarly, G2ꢀB(OH)2 (5) was firstly coupled with
(2) to afford G3ꢀBr (6), and then converted into the 3rdꢀgeneration dendron G3ꢀB(OH)2 (7).
Subsequently, the target dendrimers (G1, G2 and G3) were synthesized by Suzuki coupling of
corresponding 1stꢀ3rd generations of dendrons with tris(4ꢀbromophenyl)amine, using toluene/water
system
in
the
presence
of
tetrakis(triphenylphosphine)
palladium,
K2CO3 and
tricaprylylmethylammonium chloride, respectively (Scheme 2).

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I
I
N
(ii)
Br
Br
Br
N
(i)
(2)
+
(iii)
N
H
N
Br
G1-Br
(1)
B(OH)2
G1-B(OH)2
(3)
N
N
N
N
(iii)
(iv)
N
N
Br
B(OH)2
G2-Br
(4)
G2-B(OH)2
(5)
N
N
N
N
N
N
N
(iii)
(iv)
+ (2)
N
N
N
N
N
N
N
Br
B(OH)2
G3-Br
(6)
G3-B(OH)2
(7)
Scheme 1. Synthesis of 9-phenylcarbazole based dendrons, Gn-B(OH)2 (n = 1, 2, and 3)a
a Reagents and conditions: (i) CuI, K2CO3, 18ꢀCrownꢀ6, DMPU, 170 °C, 11h; (ii) KI, KIO3, acetic acid,
reflux, 4h; (iii) (a) nBuLi, THF, ꢀ78 °C, 1h, (b) (iPrO)3B, ꢀ78 °C, 1h; (iv) Pd(PPh3)4, K2CO3, Toluene,
50 °C, overnight.

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Br
N
Pd(PPh3)4
Dendrimers (G1, G2, G3)
GnB(OH)2
+
K2CO3
Br
Br
N
N
N
N
N
N
N
N
N
N
N
N
N
N
G1
G2
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
G3
Scheme 2. Synthesis of dendrimers (G1, G2, G3)

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1
The chemical structures of dendrons were confirmed by the H NMR (Fig. S1ꢀS6, Supporting
Information) and elemental analysis. For G2ꢀBr, the appearance of only a single peak at 8.55 ppm
indicates that G1ꢀB(OH)2 has reacted completely with 3,6ꢀdiiodoꢀ9ꢀ(4ꢀbromophenyl)carbazole (2) (Fig.
1S). In the spectrum of G3ꢀBr (Fig. 3S), the peaks at 8.59 ppm is assigned to the protonꢀi from G2ꢀ
B(OH)2, whereas that at 8.62 ppm is attributed to protonꢀp from 3,6ꢀdiiodoꢀ9ꢀ(4ꢀ
bromophenyl)carbazole, indicative of the successful coupling reaction. After conversion of bromine
atoms into boronic acid groups, relative to G2ꢀBr and G3ꢀBr, the chemical shifts of protonꢀj and k in
G2ꢀB(OH)2 and G3ꢀB(OH)2 shift apparently to low field, respectively (Fig. 2S and 4S). The measured
results by elemental analysis of the dendrons agree to their theoretical values.
N
N
N
N
i
p
N
j
h
g
k
N
N
L
N
f
m
e
d
n
o
q
r
c
a
b
d
e
h
G3ꢀ dendron
G3ꢀ dendron
b
a
c
m
f
i
g
j
k
n
P
L
q
o
r
8.6
8.4
8.2
8.0
7.8
7.6
7.4
chemical shift (ppm)
Fig. 1 1H NMR spectrum of G3 in chloroformꢀd (400 MHz).

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1
The chemical structures of three dendrimers were identified by H NMR spectroscopy, elemental
analysis and matrixꢀassisted laser desorption ionization timeꢀofꢀflight (MALDIꢀTOF) mass
1
spectrometry. In the H NMR spectrum of G1 (Fig. 5S), the triplets at 7.31 and 7.44 ppm are due to
protonꢀb and c in the carbazole moiety, while the doublets appearing at 7.36 and 7.86 ppm are
corresponded to the protonꢀg and h in the triphenylamine core, respectively. By comparison with the 1H
NMR spectra of G1 and G3ꢀBr, the peaks of G2 at 8.59 (singlet), 8.19 (doublet), 8.11 (doublet), 7.97
(doublet), 7.86 (doublet), 7.79 (doublet), 7,76 (doublet), 7.72 (doublet), 7.53 (doublet) and 7.36 ppm
(triplet) are well assigned to protonꢀi, a, f, g, k, j, h, e, d and b, respectively (Fig. 6S).
d
e
b
a
c
g
f
m
h
i
j
n
p
L
k
q
o
r
q
n
b
c
r
7.50
8.00
d
g
l
h
m
r
e
k
i
q
n
j
o
h
m
g
L
k
o
f
a
j
8.50
i
p
ppm (t1)
8.50
ppm (t2)
8.00
7.50
Fig. 2 HꢀH COSY spectrum of G3 in chloroformꢀd (400 MHz).
For G3, by comparison with the spectrum of G2, the peaks at 8.58 and 8.64 ppm (Fig. 1) are
assigned to protonꢀi and p, the doublets appearing at 8.18, 7.99 and 7.53 ppm belong to the protonꢀa, f
and d, and the triplets at 7.44 and 7.31 ppm are due to the protonꢀc and b, respectively. Nevertheless,
1
the signals of other protons in the conventional H NMR spectrum are too overlapped to be clearly

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assigned. In this regard, the twoꢀdimensional HꢀH COSY and CꢀH HSQC spectra were measured.
According to the HꢀH COSY (Fig. 2), the singlet at 8.58 ppm is correlated to a signal at 7.83 ppm,
whereas the signal at 7.83 ppm is correlated to that at 7.69 ppm. The peak at 8.58 ppm has been
assigned to the protonꢀi. Therefore, the signals at 7.83 and 7.69 ppm are attributed to the protonꢀg and
h, respectively. In addition, other chemical shifts at 8.18 ppm (protonꢀk), 7.93 ppm (protonꢀo), 7.91
ppm (protonꢀl) and 7.74 ppm (protonꢀq) are also correlated to the signals at 7.82 ppm (protonꢀj), 7.72
ppm (protonꢀn), 7.69 ppm (protonꢀm) and 7.38 ppm (protonꢀr), respectively. Furthermore, the CꢀH
HSQC spectrum in Fig. 3 reveals the following CꢀH correlated signals: carbon resonances at 111.0 ppm
for h (7.68/111.0 ppm) and m (7.67/111.0 ppm), at 119.0 ppm for i (8.58/119.0 ppm) and p (8.64/119.0
ppm), at 126.0 ppm for g (7.83/126.0 ppm) and l (7.88/126.0 ppm), at 127.5 ppm for e (7.69/127.5
ppm), j (7.80/127.5 ppm) and n (7.78/127.5 ppm), and at 128.5 ppm for f (7.99/128.5 ppm), k
(8.07/128.5 ppm) and o (7.92/128.5 ppm). Based on the HꢀH COSY and CꢀH HSQC results, all the
signals in Fig. 1 are well assigned the corresponding protons in dendrimer G3.
d
e
m
a
b
h
c
f
i
g
j
k
p
L
n
o
d
110.0
115.0
120.0
125.0
m + h
d
m h
p
i
b
a
i+ p
b
a
g
L
c
L + g
c
f
e+ j+ n
f+k+o
o
k
j n
e
130.0
ppm (t1)
8.50
8.00
7.50
ppm (t2)
Fig. 3 CꢀH HSQC spectrum of G3 in chloroformꢀd (400 MHz).

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In addition, MALDIꢀTOF mass spectrometry for each dendrimer was performed to provide the
definite evidences for the structures of dendrimers (Fig. 4). For the three generations of dendrimers, the
determined molecular weights are well consistent with the proposed structures. For example, according
to the molecular formula of C396H246N22 (G3), the calculated molecular weight of [M + Na]+ is
5334.34, while the corresponding sharp single peak in the MALDIꢀTOF spectrum appears at 5334.95.
5334.95
G3
2423.48
G2
968.40
G1
1000
2000
3000
4000
5000
6000
m/z (Da)
Fig. 4 MALDIꢀTOFꢀMS spectra of dendrimers G1ꢀG3.
The thermal stabilities of G1ꢀG3 were evaluated by thermogravimetric analysis (TGA) under
nitrogen atmosphere. As illustrated in Fig. 5, all the dendrimers exhibit excellent thermal stability with
5 % weightꢀloss temperatures (T5%) over 540 °C. Moreover, both the T5% values and residual weights at
850 °C show apparent increases with the generation of the dendrimer, indicating that the incorporation
of 9ꢀphenylcarbazole is advantageous for the resistance to heat. In addition, in contrast to G1 and G2,
G3 displays twoꢀstep degradations, locating at around 576 °C and 652 °C, respectively, suggesting that,
for the higherꢀgeneration dendrimer, the thermal cleavage firstly occurs in the outermost layer, and then
the internal dendrons and core start to decompose.

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G1
G2
G3
100
80
60
40
20
200
400
600
800
Temperature (oC)
0
200
400
600
800
Temperature (oC)
Fig. 5 TG and DTG traces of dendrimers measured at a heating rate of 10 °C minꢀ1.
Fig. 6 Computer simulations for the dendrimers G1ꢀG3.
In order to elucidate the effects of growth of generation on the crystalline behavior, photophysical
and electrochemical properties, computer modeling was carried out to reveal information of the
conformation and topological of the dendrimers using Materials Studio Modeling Software. Molecular
models were energy minimized via conjugateꢀgradient method. The algorithm was set to PolakꢀRibiere,
and the convergence and line search were equal to 0.1 and 0.5, respectively. After successive geometry

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and molecular mechanics optimizing, the energyꢀminimized structures are relaxed through dynamic
calculation at 298 K for 200 ps based on the COMPASS force field to obtain the molecular models as
illustrated in Fig. 6. Each dendrimer is constructed with three identical 9ꢀphenylcarbazoleꢀbased
dendrons symmetrically stretched from the triphenylamine core. However, the presence of the torsional
angle between the benzeneꢀcarbazole rings and bending angle of CꢀNꢀC bond gives rise to the
dendrimers greatly contorted structures, and the twisted extent is more pronounced for the dendrimer of
higher generation. For the 3rdꢀgeneration dendrimer, the bulky dendron becomes almost perpendicular
to the benzene ring owing to the increased steric hindrance and molecular internal tension.
1st heating
G1
2nd heating
G2
G3
0
50
100
150
200
250
300
350
Temperature (oC)
Fig. 7 DSC curves of dendrimers G1ꢀG3 for the first heating run (solid line) and second
heating run (dashed line).
The twisted extent and the size of the dendron significantly affect the aggregation structure of
dendrimer molecules. The DSC curves in Fig. 7 show that the bulky and distortional dendrons lead to
the dendrimer greatly decreased crystalline ability. For example, in the first heating curve, no any
melting peak can be detected for the 2nd and 3rdꢀgeneration dendrimers (G2 and G3), indicating that
G2 and G3 are amorphous in nature. On the contrary, the 1stꢀgeneration dendrimer (G1) displays a
sharp crystalline peak at 283 °C. It is noteworthy that, even though G1 can crystallize under some

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conditions, its crystalline ability is rather limited because its molecule also twists to some extent and is
rather rigid. As a result, when the melting G1 is fast cooled to room temperature and then reheated for
the second DSC run, the former crystalline peak completely disappears, showing that the melt can not
rapidly crystallize in the course of quenching treatment.
In addition, in the second heating DSC curves, G2 and G3 show glass transition temperatures at 150
and 270 °C, respectively. Relative to G2, the remarkably higher Tg value for G3 means that the
incorporation of carbazole unit and large dendron can effectively increase the steric hindrance and
rigidity of the dendrimer.
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
PL
(a)
UV-vis
N1
N2
N3
300
350
400
450
500
550
Wavelength (nm)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
PL
UV-vis
(b)
N1
N2
N3
300
350
400
450
500
550
Wavelength (nm)
Fig. 8 UVꢀvis and PL spectra of dendrimers (a) THF solutions and (b) solid films.
Photophysical properties of solution and film sample of dendrimers

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The optical properties of the dendrimers in both solution and solid state were investigated by UVꢀvis
absorption and photoluminescence (PL) spectroscopy. The UV absorption and fluorescence spectra
with normalized peak intensities are presented in Fig. 8, and the photophysical data are summarized in
Table 1. For the G1 solution sample (Fig. 8a), the UV absorption band at 293 nm is attributed to the
absorption of triphenylamine core,18 whereas that at 317ꢀ350 nm comes from the Nꢀphenylcarbazoleꢀ
based dendron.19 With the increase of generation, the band positions at 293 nm corresponding to
triphenylamine core for G2 and G3 remain almost the same as that of G1, but the intensities are
apparently increased owing to the efficient conjugation from the dendrons.20 On the other hand, relative
to G1, the former absorption band belonging to the dendron is remarkably blue shifted from 350 nm to
328 nm for G2 and 322 nm for G3. The reason can be attributed to the reduced πꢀconjugation of the Nꢀ
phenylcarbazoleꢀbased dendron caused by the increase of twisted extent with the generation.
Table 1 Photophysical data of dendrimers G1ꢀG3
Abs (nm)
Solutiona (ε × 105)b
350 (3.8), 293 (4.4)
328 (5.5), 293 (5.5)
322 (4.6), 293 (4.8)
PL (nm)
Solutiona
ΦPL
Band gap
(eV)e
dendrimer
(%)d
filmc
filmc
420
421
408
G1
G2
G3
359, 296
330, 296
323, 296
416
414
406
64
88
95
2.90
2.84
3.15
a
b
Measured in THF solution at room temperature. Mole absorption coefficient (ε): Mꢀ1 cmꢀ1,
c
d
within an error of ±0.1 × 105 Mꢀ1 cmꢀ1. Measured in solidꢀstate film. Fluorescence quantum
efficiency measured in THF using quinine sulfate dihydrate as a standard.21 e Band gaps were
calculated from the onsets of UVꢀvisible absorption spectra of G1ꢀG3 in solid films
The comparison of Fig. 8a and 8b reveals that the solution and solid film samples display the very
similar UV absorption profiles and positions of bands for both the triphenylamine core and 9ꢀ

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phenylcarbazoleꢀbased dendrons, indicating that the molecular conformations of the dendrimers do not
apparently change in both states, and the intermolecular aggregation has been significantly suppressed
by the rigid, bulky and twisted dendrons.22 According to the onset positions of UV absorptions of 427
nm, 436 nm and 393 nm for G1, G2 and G3, the band gaps of dendrimers were calculated and the
values are 2.90, 2.84 and 3.15 eV, respectively. Relative to G1, with the growth of generation, the band
gap initially displays a slight decrease (G2), and then significantly increases (G3). The possible reasons
for this phenomenon can be due to the synergistic effect of two opposing factors. Generally, the
enlarged dendron based on carbazole is advantageous for the πꢀconjugative effect, resulting in a
decreased band gap of the dendrimer. On the other hand, as revealed by the computer simulation, with
the growth of generation, the bulky dendrons become greatly twisted, which gives ride to increased
band gap. For G3, the later factor plays the major role.
Photoluminescence spectra of the dendrimers, excited at 370nm, in THF solution at a concentration
of 5×10ꢀ5 M and in thin neat films are shown in Fig. 8. The fluorescence emission spectra of three
solution samples display emissions at 416, 414 and 406 nm for G1, G2 and G3, respectively. It is
observed that, compared to G1 and G2, the emission peak of G3 apparently blueꢀshifts. The solid films
exhibit the similar PL spectra to the solution samples, indicating that the rigid dendrons and nonꢀplanar
triphenylamine core can prevent the molecules from aggregation.23 In addition, the fullꢀwidth at halfꢀ
maximum of emission spectra (FWHM) of the dendrimers are found to be only around 47ꢀ49 nm in
solutions and 46ꢀ50 nm in the solid films, implying that these dendrimers are suitable for donors that
transfer energy to fluorophores with lower band gap in EL devices.24
The quantum yields of the denrimers measured in dilute solution using quinine sulfate as a reference
are 64, 88 and 95 % for G1, G2 and G3, respectively, displaying significantly increased PL efficiencies
with the generation of dendrimer. The reason may be that the high twisting extent and reduced πꢀ
electron conjugation of dendrons are advantageous for the decrease of energy wastage for charge
transfer and nonradiative decay.

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6
4
G1
G2
G3
2
0
-2
-3.0
-2.5
0.0
0.5
1.0
1.5
Potential (V vs Ag/AgCl)
Fig. 9 Cyclic voltammograms of thin films of dendrimers in 0.1 M anhydrous acetonitrile solution of
nBu4NPF6 at room temperature.
Electrochemical behavior of dendrimers
The electrochemical properties of the dendrimers were investigated by cyclic voltammetry (CV). The
measurements were conducted at room temperature under nitrogen. The films of dendrimers obtained
by dropꢀcasting of dendrimer solution on glassy carbon electrode were used as the working electrode,
and an Ag/Ag+ electrode was used as the reference electrode, which was calibrated using the
ferrocene/ferrocenium (Fc/Fc+) redox couple (4.8 eV below the vacuum level) prior to use.25 As shown
in Fig. 9, G1 displays two electrochemical oxidation peaks, meaning that there are two independent
oxidation potentials. The first one is assigned to the oxidation of triarylamine core and the second redox
to the carbazole dendrons.24 In addition, it is observed that, with the increase of generation, the redox
couples of dendrimers shift to lower potentials, and meanwhile, the first redox wave corresponding to
the oxidation potential of dendron is overlapped with the anodic redox one of the triphenylamine core.26
Upon the cathodic scanning, the reduction process of G1 and G2 are irreversible, but the reduction
potential of G3 becomes reversible, suggesting that G1 and G2 are more favorable for oxidation (pꢀ

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doping) rather than reduction (nꢀdoping), whereas G3 is sufficiently stable and suitable for both hole
and electron injections.
Table 2 Cyclic voltammogram data of dendrimers G1ꢀG3
dendrimer
G1
E
onset(ox) (V)a
Eonset(red) (V)a
HOMO (eV)b
LUMO (eV)b
ꢀ2.26
Eg (eV)c
3.14
0.60
0.58
0.56
ꢀ2.54
ꢀ5.40
G2
ꢀ2.56
ꢀ5.38
ꢀ2.24
3.14
G3
ꢀ2.60
ꢀ5.36
ꢀ2.20
3.16
a Onset oxidation and reduction potentials versus Ag/Ag+ (0.01 V); estimated from the onset oxidation
b
c
and reduction potential by using HOMO = ꢀEonset(ox) ꢀ 4.8 eV and LUMO = ꢀEonset(red) ꢀ 4.8 eV;
27
Electrochemical band gaps determined using Eg = Eonset(ox) ꢀ Eonset(red).
On the other hand, Table 2 shows that the first oxidation potentials (Eonset(ox)) of G1, G2 and G3 are
0.60, 0.58 and 0.56 eV, respectively, indicating that synergistic effect of the 9ꢀphenyl carbazoleꢀbased
dendrons and the triphenylamine core results in outstanding electronꢀdonating capacities. Moreover, the
Eonset(ox) values of dendrimers are shifted negatively with the increase of generation from G1 to G3,
which is also attributed to the increasing content of electronꢀrich carbazole moieties. The highest
occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) of the
dendrimers were calculated from the following equations: HOMO = ꢀEonset(ox) ꢀ 4.8 eV, and LUMO = ꢀ
Eonset(red) ꢀ 4.8 eV. Accordingly, for G1, G2 and G3, the HOMO energy levels are ꢀ5.40, ꢀ5.38 and ꢀ5.36
eV, and the LUMO energy levels are ꢀ2.26, ꢀ2.24 and ꢀ2.20 eV, respectively. As can be seen, the
HOMO energy levels of these dendrimers are in the range from ꢀ5.40 to ꢀ5.36 eV, very close to the
work function of the ITO (indium tin oxide)/PEDOT (poly(3,4ꢀethylenedioxythiophene)) electrode
(work function ꢀ5.2 eV).28 This characteristics is especially beneficial to the efficient hole injection and
transport for optoelectronic materials. In addition, from the equation of Eg = Eonset(ox) ꢀ Eonset(red), the

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obtained band gaps (Eg) of G1 and G2 are 3.14 eV, whereas the value for G3 slightly increases to 3.16
eV, which is consistent with the blueꢀshifting trend observed in the PL spectra of dendrimers.
Conclusions
We have successfully synthesized three dendrimers with various generations (G1, G2, G3) consisting
of a triphenylamine core and 9ꢀphenylcarbazole based dendrons through the convergent approach. Their
chemical structures were well characterized. All the dendrimers exhibit the 5% weight loss temperature
over 540 °C. The 3rdꢀgeneration dendrimer has the Tg value of 270 °C, which is the highest among
them. The solution and solid samples have very similar UV absorption and fluorescence emission
profiles, indicating that the intermolecular aggregation has been greatly suppressed by the rigid, bulky
and twisted dendrons as revealed by the computer modeling results. As a result, the dendrimers display
narrow emission band, and with the generation growth, the quantum yields significantly increase from
63.8 % of G1 to 95.4 % of G3. In addition, CV measurements show that the dendrimers have a gradient
change for the HOMO and energy band gap with the incremental dendrons. The HOMO levels of
dendrimers are in the range from ꢀ5.43 to ꢀ5.36 eV, very close to the HOMO energy of PEDOT:PSS
((3,4ꢀpolyethylenedioxythiophene) poly(styrenesulfonate)) (work function ꢀ5.2 eV). This characteristic
is very beneficial for holeꢀtransporting and injection materials. The combination of excellent thermal
stability, excellent luminescent properties and the capacity of tuning the holeꢀtransporting properties
renders the dendrimers promising potential in OLED field.
Experimental
Materials
Tris(4ꢀbromophenyl)amine, 1,4ꢀdibromobenzene, carbazole, tetrakis(triphenylphosphine)palladium,
nBuLi and triisopropyl borate were purchased, and used without further purification. THF was freshly
distilled from sodium/benzophenone prior to use. Other commercial reagents were of analytical grade

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and used as received unless otherwise stated. All chromatographic separations were carried out on silica
gel (400 mesh).
Instrumentation
1
Conventional H NMR as well as twoꢀdimensional HꢀH Correlation Spectroscopy (COSY) and CꢀH
correlated Heteronuclear Single Quantum Coherence (HSQC) spectra were measured on a Varian
INOVA at 400 MHz with CDCl3 as solvent and tetramethysilane as internal standard.
Molecular masses were measured on a MALDI micro MX laser desorptionꢀionization timeꢀofꢀflight
mass spectrometer (MALDIꢀTOF MS). Samples were analyzed using a THF solution of the sample (3
ꢁL) mixed with 3 ꢁL of dithranol matrix (25 mg mLꢀl in THF) before loading onto a metal sample plate.
Elemental analyses were determined with an Elementar Vario EL III elemental analyzer.
Thermal gravimetric analyses (TGA) were carried out on a NETZSCH TG209C under nitrogen
atmosphere at a heating rate of 10 °C minꢀ1.
Different scanning calorimetries (DSC) were performed on a NETZSCH DSC204 with a heating rate
of 10 °C minꢀ1 under nitrogen atmosphere.
UV absorption and photoluminescence (PL) spectra were performed on a HPꢀ8453
spectrophotometer and a PTIꢀ700 luminescence spectrometer, respectively.
Cyclic voltammetries (CV) were determined on a BSA 100B electrochemical analyzer with a
conventional threeꢀelectrode configuration consisting of a glassy carbon working electrode, a platinum
auxiliary electrode and a nonꢀaqueous Ag/AgNO3 reference electrode.
Synthesis
Synthesis of 4-Carbazolyl-1-bromobenzene, G1-Br (1). The synthesis of 4ꢀcarbazolylꢀ1ꢀ
bromobenzene was carried out in the procedure described in the literature with some modifications.27 A
mixture of CuI ( 1.14 g, 6 mmol), 18ꢀCrownꢀ6 (0.53 g, 2 mmol), K2CO3 (16.6 g, 120 mmol), 1,3ꢀ
dimethylꢀ3,4,5,6ꢀ tetrahydroꢀ2(1H)ꢀpyrimidinone (DMPU) (2 mL), 1,4ꢀdibromobenzene (14.2 g, 60
mmol) and carbazole (10 g, 60 mmol) was stirred at 170 °C for 11 h under nitrogen. After cooling to

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room temperature, it was poured into 150 mL 1 ꢀHCl aqueous solution. The precipitate was filtered
N
and successively washed with NH3H2O and deionized water. The solid was further purified with
column chromatography using hexane as eluant to afford a white solid. Yield 71% (11.7 g, 0.036 mol);
1
3
m.p. 152ꢀ153 °C; H NMR (400 MHz, CDCl3): δ=8.13 (d, J(H,H) = 7.6 Hz, 2 H; ArꢀH), 7.72 (d,
3J(H,H) = 8.8 Hz, 2 H; ArꢀH), 7.45 (d, 3J(H,H) = 8.8 Hz, 2 H; ArꢀH), 7.41–7.37 (dt, 3J(H,H)1 = 6.8 Hz,
3J(H,H)2 = 6.8 Hz, 4H; ArꢀH), 7.30 ppm (t, 3J(H,H) = 6.6 Hz, 2H; ArꢀH); elemental analysis calcd (%)
for C18H12BrN: C 67.10, H 3.75, N 4.35; found: C 67.21, H 3.70, N 4.29.
Synthesis of 3,6-Diiodo-9-(4-bromophenyl)carbazole (2). 3,6ꢀdiiodoꢀ9ꢀ(4ꢀbromophenyl)carbazole
was prepared according to the procedure described previously.29 4ꢀCarbazolylꢀ1ꢀbromobenzene (0.65 g,
2 mmol) was dissolved in boiling glacial acetic acid (40 mL), and then potassium iodide (0.66 g, 3.96
mmol) and potassium iodate (0.96 g, 4.5 mmol) were added. After reacting at the refluxing temperature
under the protection of nitrogen for 4 h, the mixture was poured into 150 mL water, and the precipitate
was filtered and washed successively with water. The product was purified by recrystallization from
1
chloroform/ethanol to afford a white solid. Yield 85% (3.64 g, 6.3 mmol); m.p. 239ꢀ241 °C; H NMR
3
3
(400 MHz, CDCl3): δ=8.38 (s, 2H; ArꢀH), 7.74(d, J(H,H) = 8.8 Hz, 2H; ArꢀH), 7.67(d, J(H,H) = 8.8
3
3
Hz, 2H; ArꢀH), 7.37(d, J(H,H) = 8.2 Hz, 2H; ArꢀH), 7.11 ppm (d, J(H,H) = 8.8 Hz, 2H; ArꢀH);
elemental analysis calcd (%) for C18H10BrI2N: C 37.66, H 1.76, Br 13.92, I 44.22, N 2.44; found: C
37.56, H 1.80, Br 13.84, I 44.31, N 2.40.
Synthesis of 4-carbazolyl-1-phenylboronic acid, G1-B(OH)2 (3). 4ꢀCarbazolylꢀ1ꢀphenylboronic
acid was prepared according to a similar method described in the literature28 with some modifications.
7.2 mL of 2.5 M nBuLi (18 mmol) in hexane was added dropwise to a solution of 4ꢀcarbazolylꢀ1ꢀ
bromobenzene (4.3 g, 15 mmol) in THF (40 mL) at ꢀ78 °C. After stirring for 1h, triisopropyl borate (32
mL, 18 mmol) was added using a syringe. The reaction mixture was reacted for additional 1 h and then
was warmed slowly to room temperature and stirred overnight. The supernatant was diluted with ether

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(100 mL) and washed with water. The organic layer was dried over MgSO4, and the solution was
concentrated using a rotary evaporator. The solid was further purified with column chromatography
using a mixture of hexane and ethyl acetate as a gradient eluent to afford a white solid. Yield 87% (3.3
g, 0.011mol); m.p. 262ꢀ264 °C; 1H NMR (400 MHz, CDCl3): δ= 8.56 (d, 3J(H,H) = 8.0 Hz, 2H; ArꢀH),
8.18 (d, 3J(H,H) = 7.6 Hz, 2H; ArꢀH), 7.80 (d, 3J(H,H) = 8.0 Hz, 2H; ArꢀH), 7.56 (d, 3J(H,H) = 8.0 Hz,
2H; ArꢀH), 7.46 (t, 3J(H,H) = 7.2 Hz, 2H; ArꢀH), 7.33 ppm (t, 3J(H,H) = 7.6 Hz, 2H; ArꢀH); elemental
analysis calcd (%) for C18H14BNO2: C 75.30, H 4.91, N 4.88; found: C 75.36, H 4.82, N 4.81.
Synthesis of 4-[3’, 6’-Di(4’-Carbazolylbenzene-1’-yl)carbazolyl]-1-bromobenzene, G2-Br (4).
4ꢀ[3’, 6’ꢀDi(4’ꢀcarbazolylbenzenꢀ1’ꢀyl)carbazolyl]ꢀ1ꢀbromobenzene was prepared in the procedure
described in the literature with some modifications.30 To a mixture of G1ꢀB(OH)2 (495 mg, 1.72
mmol),
3,6ꢀdiiodoꢀ9ꢀ(4ꢀbromophenyl)carbazole
(449
mg,
0.78
mmol),
and
tetrakis(triphenylphosphine)ꢀpalladium(18 mg), toluene (30 mL) and 2 M K2CO3 (4 mL) were charged
into a 100 mLꢀroundꢀbottom flask equipped with a magnetic stirrer, a N2 inlet and a reflux condenser.
The system was heated to 50 °C and stirred at this temperature overnight. Then the mixture was poured
into water which was extracted with chloroform three times. The combined organic layer was dried
with anhydrous Na2SO4, filtered, and evaporated to dryness. The crude product was purified by silica
gel column chromatography using petroleum ether/CHCl2 as an eluent to afford an orange solid. Yield
91% (0.571 g, 0.71 mmol); m.p. >300 °C; 1H NMR (400 MHz, CDCl3): δ= 8.55 (s, 2H; ArꢀH), 8.17 (d,
3
3J(H,H) = 8.0 Hz, 4H; ArꢀH), 7.97 (d, J(H,H) = 8.0 Hz, 4H; ArꢀH), 7.82 (m, 4H; ArꢀH), 7.70 (d,
3J(H,H) = 8.4 Hz, 4H; ArꢀH), 7.57 (m, 4H; ArꢀH), 7.52 (d, 3J(H,H) = 8.8 Hz, 4H; ArꢀH), 7.44 (t, 3J(H,H)
3
= 7.2 Hz, 4H; ArꢀH), 7.30 ppm (t, J(H,H) = 7.2 Hz, 4H; ArꢀH); elemental analysis calcd (%) for
C54H34BrN3: C 80.59, H 4.26, N 5.22; found: C 80.51, H 4.33, N 5.14.
Synthesis of 4-(3’,6’-Di(4’-carbazolylbenzene-1’-yl)carbazolyl)phenylboronic Acid, G2-B(OH)2
(5). The preparation procedure of G2ꢀB(OH)2 was similar to that of G1ꢀB(OH)2 except that the

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1
precursor used was G2ꢀBr instead of G1ꢀBr. Yield 54% (0.43 g, 0.559 mmol); m.p. >300 °C; H NMR
(400 MHz, CDCl3): δ= 8.99 (s, 2H; ArꢀH), 8.17 (m, 6H; ArꢀH), 8.20 (m, 6H; ArꢀH), 7.82 (d, 3J(H,H) =
3
3
7.6 Hz, 2H; ArꢀH), 7.83 (d, J(H,H) = 8.8 Hz, 4H; ArꢀH), 7.78 (d, 2H, J(H,H) = 8.0 Hz, 2H; ArꢀH),
7.66 (d, 3J(H,H) = 7.6 Hz, 2H; ArꢀH), 7.56ꢀ7.50 (m, 8H; ArꢀH), 7.37 ppm (t, 3J(H,H) = 6.4 Hz, 4H; Arꢀ
H); elemental analysis calcd (%) for C54H36BN3O2: C 84.26, H 4.71, N 5.46; found: C 84.20, H 4.77, N
5.53.
Synthesis of 9-(4-(6-(4-(3,6-Bis(4-(9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)phenyl)-9-(4-
bromophenyl)-9H-carbazol-3-yl)phenyl)-3,6-bis(4-(9H-carbazol-9-yl)phenyl)-9H-carbazole, G3-
Br (6). The preparation procedure of G3ꢀBr was similar to that of G2ꢀBr except that the precursor used
1
was G2ꢀB(OH)2 instead of G1ꢀB(OH)2. Yield 69% (0.32 g, 0.18 mmol); m.p. >300 °C; H NMR (400
3
MHz, CDCl3): δ= 8.62 (s, 2H; ArꢀH), 8.59 (s, 4H; ArꢀH), 8.17 (d, J(H,H) = 8.0 Hz, 8H; ArꢀH), 8.06
3
3
(d, J(H,H) = 8.4 Hz, 4H; ArꢀH) , 7.99 (d, J(H,H) = 8.0 Hz, 8H; ArꢀH), 7.88ꢀ7.81 (m, 12H; ArꢀH),
3
3
7.71ꢀ7.68 (m, 12H; ArꢀH), 7.59 (d, J(H,H) = 8.8Hz, 4H; ArꢀH), 7.52 (d, J(H,H) = 8Hz, 8H; ArꢀH),
3
3
13
7.45 (t, J(H,H) = 7.6 Hz, 8H; ArꢀH), 7.32 ppm (t, J(H,H) = 7.2 Hz, 8H; ArꢀH); C NMR (CDCl3,
100MHz): δ= 141.2, 140.9, 136.2, 133.5, 132.8, 128.9, 128.6, 127.7, 127.5, 125.9, 124.4, 124.2, 123.4,
120.4, 120.0, 119.2, 110.6, 109.8 ppm; elemental analysis calcd (%) for C126H78BrN7: C 85.50, H 4.44,
N 5.54; found, C 85.45, H 4.41, N 5.58.
Synthesis of 4-(3,6-bis(4-(3,6-bis(4-(9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)phenyl)-9H-
carbazol-9-yl)phenylboronic Acid, G3-B(OH)2 (7). The preparation procedure of G3ꢀB(OH)2 was
similar to that of G2ꢀB(OH)2 except that the precursor used was G3ꢀBr instead of G2ꢀBr. Yield 50%
1
(0.27 g, 0.156 mmol); m.p. >300 °C; H NMR (400 MHz, CDCl3): δ= 8.62 (s, 2H; ArꢀH), 8.59 (s, 4H;
ArꢀH), 8.17 (d, 3J(H,H) = 8.0 Hz, 8H; ArꢀH), 8.07 (d, 3J(H,H) = 8.4 Hz, 4H; ArꢀH) , 7.99 (d, 3J(H,H) =
8.0 Hz, 8H; ArꢀH), 7.87ꢀ7.76 (m, 12H; ArꢀH), 7.71ꢀ7.63 (m, 16H; ArꢀH), 7.52 (d, 3J(H,H) = 8.4Hz, 8H;
3
3
ArꢀH), 7.45 (t, J(H,H) = 7.6 Hz, 8H; ArꢀH), 7.31 ppm (t, J(H,H) = 7.6 Hz, 8H; ArꢀH); 13C NMR

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(CDCl3, 100MHz): δ = 141.1, 140.9, 136.3, 132.9, 128.6, 127.3, 126.0, 124.1, 123.4, 120.4, 119.9,
118.9, 110.6, 109.8 ppm; elemental analysis calcd (%) for C126H80BN7O2: C 87.23, H 4.65, N 5.65;
found, C 87.19, H 4.68, N 5.61.
Synthesis of Dendrimers. The 1stꢀ3rd generations of Dendrimers G1, G2, G3 were synthesized in
the similar procedure, so only a typical synthesis procedure for G1 was described as follows: G1ꢀ
B(OH)2 (0.35 g, 12 mmol), tris(4ꢀbromophenyl)amine (0.1 g, 0.2 mmol), and
tetrakis(triphenylphosphine) palladium (0.0233 g, 0. 02 mmol) were added to an airꢀfree twoꢀphase
system composed of toluene (30 mL) and 2 M K2CO3 aqueous solution (10 mL). The resultant mixture
was vigorously stirred under an argon atmosphere at 80 °C for 24 h. The organic layer was separated
and the aqueous phase was extracted with diethyl ether three times. The organic layers were combined
and washed with brine and dried over anhydrous MgSO4. The solvent was evaporated and the residue
went through silicaꢀgel column.
1
G1: Yield 85% (0.12 g, 0.124 mmol); m.p. >300 °C; H NMR (400 MHz, CDCl3): δ = 8.17 (d,
3
3J(H,H) = 7.6 Hz, 6H; ArꢀH), 7.84 (d, J(H,H) = 8 Hz, 6H; ArꢀH), 7.68ꢀ7.64 (m, 12H; ArꢀH), 7.49 (d,
3J(H,H) = 8 Hz, 6H; ArꢀH), 7.43 (t, 3J(H,H) = 6.8 Hz, 6H; ArꢀH), 7.36 (d, 3J(H,H) = 7.6 Hz, 6H; ArꢀH),
3
7.31 ppm (t, J(H,H) = 7.6 Hz, 6H; ArꢀH); IR (KBr): ν = 3042 (CꢀH), 1598 (C=C), 1500 (C=C), 1451
(C=C), 1333 (CꢀN), 1066, 814 (CꢀH), 748 (CꢀH) cmꢀ1; 13C NMR (CDCl3, 100MHz): δ = 147.1, 140.7,
139.7, 136.5, 134.8, 127.9, 127.4, 126.0, 124.6, 123.4, 120.4, 120.0, 109.8 ppm; MS (MALDIꢀTOF):
m/z calcd for C72H48N4: 969.18; found: 968.40; elemental analysis calcd (%) for C72H48N4: C 89.23, H
4.99, N 5.78; found: C 89.20, H 4.96, N 5.82.
1
G2: Yield 72% (0.09 g, 0.037 mmol); m.p. >300 °C; H NMR (400 MHz, CDCl3): δ = 8.59 (s, 6H;
ArꢀH), 8.19 (d, 3J(H,H) = 7.6 Hz, 12H; ArꢀH), 8.00 (d, 3J(H,H) = 6.8 Hz, 12H; ArꢀH), 7.95 (d, 3J(H,H)
= 7.6 Hz, 6H; ArꢀH), 7.85 (d, 3J(H,H) = 7.6 Hz, 6H; ArꢀH), 7.80ꢀ7.76 (m, 30H; ArꢀH), 7.53 (d, 3J(H,H)
= 7.6 Hz, 12H; ArꢀH), 7.46 (m, 18H; ArꢀH), 7.32 ppm (t, 3J(H,H) = 6.8 Hz, 12H; ArꢀH); IR (KBr): ν =
3044 (CꢀH), 1600 (C=C), 1500 (C=C), 1453 (C=C), 1335 (CꢀN), 1069, 817 (CꢀH), 751 (CꢀH) cmꢀ1; 13C

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NMR (CDCl3, 100MHz): δ = 147.0, 141.1, 141.0, 139.6, 136.3, 134.9, 132.8, 128.6, 127.4, 125.9,
124.7, 124.1, 123.4, 120.4, 120.0, 119.2,110.8, 109.8 ppm; MS (MALDIꢀTOF): m/z calcd for
C180H114N10: 2416.93; found 2423.48; elemental analysis calcd (%) for C180H114N10: C 89.45, H 4.75, N
5.80; found: C 89.49, H 4.71, N 5.75.
1
G3: Yield 43% (0.054 g, 0.01 mmol); m.p. >300 °C; H NMR (400 MHz, CDCl3): δ = 8.64 (s, 6H;
ArꢀH), 8.58 (s, 12H; ArꢀH), 8.17 (d, 3J(H,H) = 7.6 Hz, 24H; ArꢀH), 8.07 (d, 3J(H,H) = 7.2 Hz, 12H; Arꢀ
H), 7.99 (d, 3J(H,H) = 7.6 Hz, 24H; ArꢀH), 7.93ꢀ7.75 (m, 48H; ArꢀH), 7.70ꢀ7.67 (m, 42H; ArꢀH), 7.52
(d, 3J(H,H) = 7,6 Hz, 24H; ArꢀH), 7.45ꢀ7.38 (m, 30H; ArꢀH), 7.30 ppm (t, 3J(H,H) = 7.2 Hz, 24H; Arꢀ
H); IR (KBr): ν = 3046 (CꢀH), 1602 (C=C), 1503 (C=C), 1457 (C=C), 1338 (CꢀN), 1069, 818 (CꢀH),
751 (CꢀH) cmꢀ1; 13C NMR (CDCl3, 100MHz): δ = 141.4, 141.1, 136.4, 133.2, 128.8, 127.5, 126.1,
124.4, 123.5, 120.6, 120.2, 119.3, 110.9, 110.1 ppm; MS (MALDIꢀTOF): m/z calcd for C396H246N22:
5312.34; found: 5334.95 [M + Na]+; elemental analysis calcd (%) for C396H246N22: C 89.53, H 4.67, N
5.80; found: C 89.57, H 4.65, N 5.77.
References
1 (a) O. A. Matthews, A. N. Shipway and J. F. Stoddart, Prog. Polym. Sci., 1998, 23, 1–56; (b) S. M.
Grayson and J. M. Frechet, Chem. Rev., 2001, 101, 3819–3868.
2 (a) A. K. Patri, J. F. KukowskaꢀLatallo and J. R. Baker, Adv. Drug Delivery Rev., 2005, 57, 2203–
2214; (b) R. Esfand and D. A. Tomalia, Drug Discovery Today, 2001, 6, 427–436; (c) F. M. H. de
Groot, C. Albrecht, R. Koekkoek, P. H. Beusker and H. W. Scheeren, Angew. Chem. Int. Ed., 2003,
42, 4490–4494; (d) R. J. Amir, N. Pessah, M. Shamis and D. Shabat, Angew. Chem. Int. Ed., 2003,
42, 4494–4499.
3 (a) S. D. Konda, M. Aref, S. Wang, M. Brechbiel and E. C. Wiener, Bio. And Med., 2001, 12, 104–
113; (b) D. A. Fulton, E. M. Elemento, S. Aime, L. Chaabane and M. Botta, D. Parker, Chem.
Commun., 2006, 1064–1066; (c) J. L. Mynar, T. J. Lowery, D. E. Wemmer, A. Pines and J. M.

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Organic & Biomolecular Chemistry
View Online
Frechet, J. Am. Chem. Soc., 2006, 128, 6334–6335.
4 (a) G. Koten and J. T. B. H. Jastrzebski, J. Mol. Catal. A: Chem., 1999, 146, 317–323; (b) V.
Maraval, R. Laurent, A. M. Caminade and J. P. Majoral, Organometallics, 2000, 19, 4025–4029;
(c) N. N. Hoover, B. J. Auten and B. D. Chandler, J. Phys. Chem. B, 2006, 110, 8606–8612.
5 (a) B. Lohse, R. Vestberg, M. T. Ivanov, Soren Hvilsted, R. H. Berg, C. J. Hawker and P. S.
Ramanujam, Chem. Mater., 2006, 18, 6715–6720; (b) T. H. Ghaddar, J. F. Wishart, D. W.
Thompson, J. K. Whitesell and M. A. Fox, J. Am. Chem. Soc., 2002, 124, 8285–8289.
6 (a) J. P. Lu, P. F. Xia, P. K. Lo, Y. Tao and M. S. Wong, Chem. Mater., 2006, 18, 6194–6203; (b)
N. Satoh, T. Nskashima and K. Yamamoto, J. Am. Chem. Soc., 2005, 127, 13030–13038; (c) T.
Hasobe, Y. Kashiwagi, M. A. Absalom, J. Sly, K. Hosomizu, M. J. Crossley, H. Imahori, P. V.
Kamat and S. Fukuzumi, Adv. Mater., 2004, 16, 975–979; (d) W. L. Rance, B. L. Rupert, W. J.
Mitchell, M. E. Kose, D. S. Ginley, S. E. Shaheen, G. Rumbles and N. Kopidakis, J. Phys. Chem. C,
2010, 114, 22269–22276.
7 (a) T. S. Qin, G. Zhou, H. Scheiber, R. E. Bauer, M. Baumgarten, C. E. Anson, E. J. W. List and K.
Mullen, Angew. Chem. Int. Ed., 2008, 47, 8292–8296; (b) L. Zhao, C. Li, Y. Zhang, X. H. Zhu, J. B.
Peng and Y. Cao, Macromol. Rapid Commun., 2006, 27, 914–920; (c) H. J. Zhang, X. J. Xu, W. F.
Qiu, T. Qi, X. K. Gao, Y. Liu, K. Lu, C. Y. Du, G. Yu and Y. Q. Liu, J. Phys. Chem. C, 2008, 112,
13258–13263; (d) J. You, G. Y. Li, R. J. Wang, Q. P. Nie, Z. G. Wang and J. Y. Li, Phys. Chem.
Chem. Phys., 2011, 13, 17825–17830.
8 (a) Y. Hang, Z. P. Fei, M. H. Sun, Z. S. Bo and W. Z. Liang, Macromol. Rapid Commun., 2007, 28,
1017–1023; (b) P. Furuta, J. Brookes, M. E. Thompson and J. M. J. Frechet, J. Am. Chem. Soc.,
2003, 125, 13165–13172; (c) M. Halim, J. N. G. Pillow, I. D. W. Samuel and P. L. Burn, Adv.
Mater., 1999, 11, 371–374; (d) A. Herrmann, T. Weil, V. Sinigersky, U. M. Wiesler, T. Vosch, J.
Hofkens and F. C. D. Schryver, K. Mullen, Chem. Eur. J., 2001, 7, 4844–4853.
9 (a) P. Du, W. H. Zhu, Y. Q. Xie, F. Zhao, C. F. Ku, Y. Cao, C. P. Chang and H. Tian,

Organic & Biomolecular Chemistry
Page 26 of 29
View Online
Macromolecules, 2004, 37, 4387–4398; (b) D. J. Liu, S. D. Feyter, M. Cotlet, A. Stefan, U. M.
Wiesler, A. Herrmann, D. GrebelꢀKoehler, J. Q. Qu, K. Mullen and F. C. D. Schryver,
Macromolecules, 2003, 36, 5918–5925; (c) A. P. Kulkarni, C. J. Tonzola, A. Babel and S. A.
Jenekhe, Chem. Mater., 2004, 16, 4556–4573; (d) J. M. Lupton, I. D. W. Samuel, R. Beavington,
M. J. Frampton, P. L. Burn and H. Bassler, Phys. Rev. B, 2001, 63, 155206.
10 K. Albrecht and K. Yamamoto, J. Am. Chem. Soc., 2009, 131, 2244–2251.
11 (a) R. M. Adhikari, R. Mondal, B. K. Shah and D. C. Neckers, J. Org. Chem., 2007, 72, 4727–
4732; (b) K. L. Paik, N. S. Baek and H. K. Kim, Macromolecules, 2002, 35, 6782–6791; (c) K. R. J.
Thomas, J. T. Lin, Y. T. Tao and C. H. Chuen, Chem. Mater., 2002, 14, 3852–3859; (d) M. Sonntag
and P. Strohriegl, Chem. Mater., 2004, 16, 4736–4742.
12 (a) S. Tang, M. R. Liu, P. Lu, H. Xia, M. Li, Z. Q. Xie, F. Z. Shen, C. Gu, H. P. Wang, B. Yang and
Y. G. Ma, Adv. Funct. Mater., 2007, 17, 2869–2877; (b) K. T. Wong, Y. H. Lin, H. H. Wu and F.
Fungo, Org. Lett., 2007, 9, 4531–4534; (c) J. Yang, T. L. Ye, D. G. Ma and Q. Zhang, Synth. Metal,
2011, 161, 330ꢀ334.
13 (a) Z. G. Zhu and J. S. Moore, J. Org. Chem., 2000, 65, 116–123; (b) Z. H. Li and M. S. Wong, Org.
Lett. 2006, 8, 1499–1502; (c) Y. Li, J. F. Ding, M. Day, Y. Tao, J. P. Lu and M. D’iorio, Chem.
Mater., 2004, 16, 2165–2173; (d) V. Promarak, A. Punkvuang, T. Sudyoadsuk, S. Jungsuttiwong, S.
Saengsuwan, T. Keawin and K. Sirithip, Tetrahedron, 2007, 63, 8881–8890.
14 (a) N. Satoh, J. S. Cho, M. Higuchi and K. Yamamoto, J. Am. Chem. Soc., 2003, 125, 8104–8106;
(b) A. Kimoto, J. S. Cho, M. Higuchi and K. Yamamoto, Macromolecules, 2004, 37, 5531–5537;
(c) J. Natera, L. Otero, F. D’Eramo, L. Sereno and F. Fungo, Macromolecules, 2009, 42, 626–635.
(d) A. Hameurlaine and W. Dehaen, Tetrahedron Lett., 2003, 44, 957–959; (e) F. Loiseau, S.
Campagna, A. Hameurlaine and W. Dehaen, J. Am. Chem. Soc., 2005, 127, 11352–11363; (f) K.
Albrecht, Y. Kasai, A. Kimoto and K. Yamamoto, Macromolecules, 2004, 41, 3793–3800; M. J.
Xiong, Z. H. Li and S. Wong, Aust. J. Chem., 2007, 60, 603–607.

Page 27 of 29
Organic & Biomolecular Chemistry
View Online
15 Z. H. Zhao, H. Jin, Y. X. Zhang, Z. H. Shen, D. C. Zou and X. H. Fan, Macromolecules, 2011, 44,
1405–1413.
16 H. Q. Zhang, S. M. Wang, Y. Q. Li, B. Zhang, C. X. Du, X. J. Wan and Y. S. Chen, Tetrahedron,
2009, 65, 4455–4463.
17 (a) G. S. Liou, Y. L. Yang, W. C. Chen and Y. O. Su, J. Polym. Sci. Part A: Polym. Chem., 2007,
45, 3292–3302; (b) H. W. Chang, K. H. Lin, C. C. Chueh, G. S. Liou and W. C. Chen, J. Polym.
Sci. Part A: Polym. Chem., 2009, 47, 4037–4050.
18 (a) Z. Q. Gao, Z. H. Li, P. F. Xia, M. S. Wong, K. W. Cheah and C. H. Chen, Adv. Funct. Mater.,
2007, 17, 3194–3199; (b) Z. Ge, T. Hayakawa, S. Ando, M. Ueda, T. Akiike, H. Miyamoto, T.
Kajita and M. Kakimoto, Chem. Mater., 2008, 20, 2532–2537.
19 F. S. Liang, T. Kurata, H. Nishide and J. J. Kido, J. Polym. Sci. Part A: Polym. Chem., 2005, 43,
5765–5773.
20 Z. Zhao, J. H. Li, X. Chen, X. Wang, P. Lu and Y. Yang, J. Org. Chem., 2009, 74, 383–395.
21 Y. Lin, Z. K. Chen, T. L. Ye, Y. F. Dai, D. G. Ma, Z. Ma, Q. D. Liu and Y. Chen, J. Polym. Sci.
Part A: Polym. Chem., 2010, 48, 292–301.
22 H. H. Sung and H. C. Lin, Macromolecules, 2004, 37, 7945–7954.
23 Z. J. Ning, Z. Chen, Q. Zhang, Y. L. Yan, S. X. Qian, Y. Cao and H. Tian, Adv. Funct. Mater.,
2007, 17, 3799–3807.
24 A. Kulasi, H. Yi and A. Iraqi, J. Polym. Sci. Part A: Polym. Chem., 2007, 45, 5957–5967.
25 J. P. Lu, P. F. Xia, P. K. Lo, Y. Tao and M. S. Wong, Chem. Mater., 2006, 18, 6194–6203.
26 A. Iraqi, T. G. Simmance, H. Yi, M. Stevenson and D. G. Lidzey, Chem. Mater., 2006, 18, 5789–
5797.
27 Q. Peng, M. Li, S. Lu and X. Tang, Macromol. Rapid Commun., 2007, 28, 785–791.
28 F. I. Wu, P. I. Shih and C. F. Shu, Macromolecules, 2005, 38, 9028–9036.
29 Q. Zhang, J. Chen, Y. Cheng, L. Wang, D. Ma, X. Jing and F. Wang, J. Mater. Chem., 2004, 14,

Organic & Biomolecular Chemistry
Page 28 of 29
View Online
895–900.
30 A. L. Kanibolotsky, R. Berridge, P. J. Skabara, I. F. Perepichka, D. D. C. Bradley and M. Koeberg,
J. Am. Chem. Soc., 2004, 126, 13695–13702.

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Graphic abstract
Starburst dendrimers consisting of triphenylamine
core
and
9-phenylcarbazole-based
dendrons:
synthesis and property
Jia You, Guiyang Li and Zhonggang Wang*
State Key Laboratory of Fine Chemicals, Department of Polymer Science and Materials, School of
Chemical Engineering. Dalian University of Technology, Dalian 116023, P. R. China
Email: zgwang@dlut.edu.cn