Engineering the Interconnecting Position of Star-Shaped Donor–π–Acceptor Molecules Based on Triazine, Spirofluorene, and Triphenylamine Moieties for Color Tuning from Deep Blue to Green

Article abstract of DOI:10.1002/asia.201600727

Pi-conjugated organic molecules featuring the donor–bridge–acceptor (D–π–A) structure have been widely used in semiconducting materials owing to their rigid structure, good thermal stability, excellent charge transfer, and high emission efficiency. To investigate the effect of the D–π–A molecular structure on the photophysical properties, in this contribution, three star-shaped D–π–A isomers based on the 2,4,6-triphenyl-1,3,5-triazine, spirofluorene, and triphenylamine moieties, that is, p-TFTPA, mp-TFTPA, and m-TFTPA, were synthesized by elaborately engineering the interconnecting position in the building-block units. The optophysical properties of these compounds were systematically explored by experiments and theory calculations. Definitively, changing the interconnecting position in these molecules played a significant role in the degree of π conjugation, which resulted in tunable emission colors from deep blue to green. Moreover, these isomers were employed as emissive dopants in organic light-emitting diodes. The highest external quantum efficiency of 2.3 % and current efficiency of 6.2 cd A^?1 were achieved by using the p-TFTPA based device. This research demonstrates a feasible way to realize blue emitters by engineering D–π–A conjugation.

Full text of DOI:10.1002/asia.201600727

CHEMISTRY
AN ASIAN JOURNAL
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Accepted Article
Title: Engineering The Interconnection Position of Star-Shaped D-π-A Molecules
Based on Triazine, Spirofluorene and Triphenylamine Moieties for Color Tu-
ning from Deep blue to Green
Authors: Yafei Wang; Wanhui Liu; Jiyong Deng; Guohua Xie; Yuanwei Liao; Zuo-
ming Qu; Hua Tan; Yu Liu; Weiguo Zhu
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Engineering The Interconnection Position of Star-Shaped D-π-A
Molecules Based on Triazine, Spirofluorene and Triphenylamine
Moieties for Color Tuning from Deep blue to Green
Yafei Wang†#§*, Wanhui Liu†, Jiyong Deng‡, Guohua Xie△*, Yuanwei Liao†, Zuoming Qu†, Hua Tan†, Yu
Liu†, Weiguo Zhu#
Abstract: π-Conjugated organic molecule featuring donor-bridge-
acceptor (D-π-A) structure has been widely used in semiconducting
materials due to their rigid structure, good thermal stability, excellent
charge transfer and high emission efficiency. To investigate the
effect of D-π-A molecular structure on the photophysical property, in
this contribution, three star-shaped D-π-A isomers based on 2,4,6-
tri(phenyl)-1,3,5-triazine, spirofluorene and triphenylamine moieties,
p-TFT, mp-TFT and m-TFT, were synthesized via elaborately
engineering the interconnection position among the building block
units. The optophysical properties of these compounds were
systematically explored by experiment and theory calculation.
Definitely, the changed interconnection position in these molecules
plays a significant role on the degree of π conjugation, which results
in tunable emission colors from deep blue to green. Moreover, these
isomers have been employed as the emissive dopants in organic
light-emitting diodes. A highest external quantum efficiency and
current efficiency of 2.3 % and 6.2 cd/A were respectively achieved
by the p-TFT based device. This research demonstrates a feasible
way to realize blue emitter via engineering D-π-A conjugation.
obstacles for developing D-π-A blue emitters.
π-Conjugated star-shaped molecules possessing D-A
framework have been widely used in the semiconductor
materials due to their good solubility, film-forming properties and
ease of the energy gap tuning.[15,16] 2,4,6-Tris(phenyl)-1,3,5-
triazine is known to be dendritic framework, rigid skeleton and
good electron conductor and therefore have been used as a
promising acceptor core in star-shaped molecules.[17-20] For
example, Wang and his coworkers synthesized the star-shaped
compounds of 2,4,6-tris(di-2-pyridylamino)-1,3,5-triazine and
2,4,6-tris[p-(di-2-pyridylamino)phenyl]-1,3,5-triazine that exhibit-
ed blue emissions in OLEDs.[21] Matulaitis et al. prepared a
series of bipolar star-shaped molecules based on 2,4,6-
tri(phenyl)-1,3,5-triazine unit and carbazole derivatives. Although
these star-shaped D-A compounds showed blue emission,
relatively low current efficiency of 0.5 cd/A was achieved in the
OLEDs.[13] Particularly, recent research has demonstrated that
the triazine derivatives are the effective building block for the
thermally-activated delayed fluorescence (TADF) molecule.[22,23]
To this end, our recent efforts have focused on the push-pull
effect of the 2,4,6-tri(phenyl)-1,3,5-triazine based starburst
molecule on the photophysical property.
Introduction
Compared to the acceptor units, the donor units have made
much more progress in π-conjugated emission materials, such
as triphenylamine,[24-27] carbazole,[28-30] phenothiazine[31] and so
on. Considering blue emission, good charge-transporting and
Over the last two decades, π-conjugated organic molecules
featuring donor-bridge-acceptor (D-π-A) structure, have
garnered much interest as semiconductor materials in the field
of organic light-emitting diodes (OLEDs),[1-3] organic photovoltaic
devices (OPV)[4-6] and organic field effect transistors (OFET).[7,8]
Since the D-π-A organic molecules possess the advantages of
good charge transport, electron-rich feature and fascinating
optical property, numerous these molecules have been
developed as effective emitters or host materials in OLEDs.[9-11]
However, few D-π-A molecules can be employed as a deep blue
emitter because of the strong intramolecular charge transfer of
D-π-A molecules usually leading to a red-shifted emission
spectrum.[12-14] In addition, the conjugation length of D-π-A
molecules also plays an important role in tuning the emission
color. Therefore, these deficiencies are the major remaining
high
emission
efficiency,[32,33]
the
spirofluorene
and
triphenylamine units are chosen as the π-conjugated bridge and
donor moiety, respectively. Herein, the motif in this work was to
prepare a series of star-shaped D-π-A molecules with blue
emission based on the triazine, spirofluorene and triphenylamine
moieties. In this contribution, three star-shaped D-π-A isomers
of p-TFT, mp-TFT and m-TFT (Chart 1) were designed and
prepared, in which 2,4,6-tri(phenyl)-1,3,5-triazine (T) is
employed as the acceptor core, spirofluorene as the π-
conjugated bridge (F) and triphenylamine (T) as the donor unit.
Through engineering the interconnection position (p, mp or m)
between donor and bridge moieties (or bridge and acceptor), the
structure-property relationship of these star-shaped D-π-A
molecules have been systematically explored. Interestingly, the
emission color is dramatically tuned over a wide wavelength
range (from deep blue to green) by simple modification of the
molecular structure, ascribed to the changed degree of
conjugation.
[a]
Dr. Y. Wang, Dr. Y. Liu, Dr. H. Tan, Prof. W. Zhu, Mr. W. Liu, Miss
Y. Liao, Mr. Z. Quo. College of Chemistry, Xiangtan
University,Xiangtan City, Hunan, 411105, PR China.
E-mail: qiji830404@hotmail.com
[b]
[c]
Dr. Guohua Xie. Department of Chemistry, Wuhan University,
Wuhan, Hubei, 430072, PR China.
E-mail: guohua.xie@whu.edu.cn
Dr. Jiyong Deng. School of Chemistry and Chemical Engineering,
Hunan Institute of Engineering, Xiangtan 411104, PR China
Supporting information for this article is given via a link at the end of
the document.
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Chart 1. Molecular structures of p-TFT, mp-TFT and m-TFT.
Reaction conditions: (a) 1,10-Phenanthroline hydrate, CuI, KOH, toluene, 135oC, 12 h, yield, 1a: 76%, 1b: 64%; (b) bis(pinacolato)diboron, CH3COOK,
PdCl2(dppf), 1,4-dioxane, 80oC, 24 h, yield, 2a: 82%, 2b: 76%; (c) n-BuLi, THF, -78oC, 4 h. (d) HCl, CH3COOH, reflux, 1 h, yield, 60%; (e) TfOH, CH2Cl2, room
temperature, overnight, yield, 4a: 64%, 4b: 59%; (f) bis(pinacolato)diboron, CH3COOK, PdCl2(dppf), 1,4-dioxane, 80oC, 24 h, yield, 5a: 76%, 5b: 72%; (g) 2 M
K2CO3, Pd(PPh3)4, THF, 85oC, 18 h, yield, 6a: 52%, 6b: 48%; (h) 2 M K2CO3, Pd(PPh3)4, THF, 85oC, 24 h, yield: p-TFT: 48%, mp-TFT: 46%, m-TFT: 42%.
Scheme 1. Synthetic routes of p-TFT, mp-TFT and m-TFT.
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the degrees of π-conjugation of p-TFT, mp-TFT and m-TFT
decrease successively (p-TFT > mp-TFT > m-TFT), which is
caused by the changed interconnection position among
Results and Discussion
triphenylamine, spirofluorene and triazine units.[35] As
a
Synthesis and Characterization
consequence, the optical bandgaps of p-TFT, mp-TFT and m-
TFT were evaluated to be 2.71, 2.88 and 3.07 eV, respectively.
To further investigate the effect of the linkage position on
photoluminescent (PL) property, initially, the emission spectra of
all compounds were measured in CH2Cl2 solution (10-5 M) with
the excitation wavelength of 380 nm at room temperature. As
shown in Figure 2a, all compounds present broad and
structureless emission profiles in a range from deep blue to red
region, assigning to the ICT transition state.[22,36] Compound m-
TFT shows a deep blue emission centered at 406 nm.
Conversely, p-TFT and mp-TFT display both high-energy
emission (454 nm and 474 nm) and low-energy emission (627
nm and 629 nm), in which the long wavelength emissions are
attributed to the solvatochromism effect (see below).
Furthermore, the emissions of all compounds were measured in
various solvents with different polarity (ESI†, CH2Cl2, THF,
toluene and ethyl acetate). A remarkable solvatochromism effect
was observed, which supports the charge transfer state in
solution. The luminescent lifetimes (τ) for all compounds are in
the nanosecond regime (Table 1), suggesting that the emission
originates from fluorescence. Using 9,10-dibromoanthracene as
a reference (Φ=0.89, in ethanol),[37] the photoluminescence
quantum yields (Φ) of p-TFT, mp-TFT and m-TFT are evaluated
to be 0.27, 0.15 and 0.11 in CH2Cl2 at room temperature,
respectively.
The synthetic routes of p-TFT, mp-TFT and m-TFT are shown
in Scheme 1, and the detailed synthetic procedures are
described in the experimental section. Compounds 2 (2a and
2b) were prepared via Ullmann coupling using CuI and 1,10-
phenanthroline as the catalysts, and then followed by borylation
reaction. Spirofluorene derivative (3) was synthesized according
to the previous report.[34] The condensation reaction of 4-
bromobenzonitrile afforded 1,3,5-triazine core (4a and 4b) in the
presence of trifluoromethanesulfonic acid. Then, compounds 4
reacted with bis(pinacolato)diboron to yield the precursors 5 (5a
and 5b) using PdCl2(dppf) as the catalyst. Finally, the target
compounds were achieved through continuous two-step Suzuki
coupling reaction. All the target compounds were characterized
by 1H NMR, 13C NMR and TOF-MS (ESI†). The
thermogravimetric analysis (TGA) data reveal that all
compounds possess good thermal stability with the
decomposition temperature (Td) of 412oC (p-TFT), 374oC (mp-
TFT) and 437oC (m-TFT) at 5 % weight loss, respectively.
Photophysical Properties
Compared to the PL spectra in solution, the emissions show
distinctly bathochromic shifts (ca. 80-100 nm, see Table 1) in
neat film owing to the planar structure of the triazine core.
Notably, the decreased π-conjugation of p-TFT, mp-TFT and m-
TFT leads to a hypochromatic shift of the onset of PL spectra
both in solution and in neat film, which is also well matched with
the change tendency of the absorption edge. The
phosphorescence emission spectra measured in frozen toluene
at 77 K are shown in Figure 3. Fine-structured emissions with
large red shifts (80-100 nm) are observed for the compounds at
low temperature. From the onset of the phosphorescent spectra,
the triplet energy values of p-TFT, mp-TFT and m-TFT are
evaluated to be 2.41, 2.46 and 2.58 eV, respectively.
Figure 1. UV-vis absorption spectra of p-TFT, mp-TFT and m-TFT in CH2Cl2.
Theoretical Calculations
The relationship between geometrical and electronic
properties of these homologous series were carried out with
density functional theory (DFT) using the B3LYP functional
(Gaussian 09 program). The calculated highest occupied
molecular orbitals (HOMOs) and lowest unoccupied molecular
orbitals (LUMOs) of three compounds are depicted in Figure 4.
The dihedral angles between the 2,4,6-tri(phenyl)-1,3,5-triazine
and spirofluorene (or spirofluorene and triphenylamine) moieties
are almost the same for these three compounds, which suggests
that there is negligible effect of linkage position on the dihedral
angles. Notably, it is distinctly different for the HOMO and LUMO
distributions of all compounds. The spatially separated HOMO
and LUMO distributions suggest that there is a large charge-
Figure 1 depicts the UV-vis absorption spectra of p-TFT, mp-
TFT and m-TFT in CH2Cl2 (10-5 M), and the relevant data are
listed in Table 1. All of the compounds show two clear
absorption bands between 250 nm and 500 nm. The high-
energy absorption bands are ascribed to the π-π* transitions of
phenyls (triphenylamine, spirofluorene and triazine) while the
low energy absorption bands are assigned to the intramolecular
charge transfer (ICT) transition (from the donor unit to the accept
unit).[22] Compared with p-TFT and mp-TFT, m-TFT has a
relative weak ICT absorption character. Additionally, the
absorption edges of p-TFT, mp-TFT and m-TFT occur obviously
hypochromatic shifts in sequence. These phenomena imply that
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transfer character in these compounds. The HOMOs of p-TFT
and mp-TFT show the same pattern at the one of triphenylamine
and spirofluorene units, while their LUMOs display different
electron population. The LUMO of p-TFT is delocalized over the
Figure 2. Normalized PL spectra of p-TFT, mp-TFT and m-TFT: (a) in CH2Cl2 solution; (b) in neat film.
Figure 3. The phosphorescence spectra of p-TFT, mp-TFT and m-TFT measured in frozen toluene at 77 K.
Table 1. Photophysical data of p-TFT, mp-TFT and m-TFT
Compounds
λabsorption/nma
λem
λem
τ
Td
Eox
EHOMO
Eopt
Φ
g
(105 M-1 cm-1)
/nm
/nmd
/nse
/oCf
/Vg
/eVh
/eVi
p-TFT
283 (1.09), 298 (1.16), 310 (1.25), 347
(1.40), 393 (1.71)
b474
b629sh
c550
b454sh
b627
c538
553,
598sh
<5
<5
10
412
374
437
0.39
0.42
0.46
5.19
5.22
5.26
2.71
0.27j
0.043k
mp-TFT
m-TFT
285 (1.53), 297 (1.44), 309 (1.32), 347
(1.04), 374 (1.42)
539,
579sh
2.88
3.07
0.15j
0.039k
282 (1.44), 298 (1.60), 310 (1.88), 332
(1.62)
b406
c538
508,
547sh
0.11j
0.007k
593weak
Measure conditions: a,b,e) in toluene solution (10-5 M) at room temperature; c) in neat film at room temperature; d) in toluene solution (10-5 M) at 77 K; f) 5%
weight loss in N2; g) data collected from the maximum peak verse Fc/Fc+; h) EHOMO = – (Eox + 4.8) eV; i) evaluated from the UV-vis absorption spectra, Eopt
1240/λabsorption; j) Measured in CH2Cl2 solution; k) Measured in neat film.
=
g
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p-TFT
mp-TFT
m-TFT
HOMO
LUMO
Figure 4. Molecular orbital distributions of p-TFT, mp-TFT and m-TFT.
whole 2,4,6-triphenyl-1,3,5-triazine core with some contributions
from the spirofluorene unit. Conversely, the LUMO of mp-TFT is
localized only on the 2,4,6-tri(phenyl)-1,3,5-triazine moiety. For
m-TFT, the HOMO is localized at one of the triphenylamine units
and the LUMO are distributed on the 1,3,5-triazine core with two
phenyl rings. Obviously, the interconnection position in these
star-shaped molecules has a significant influence on the
electron density distributions of HOMO and LUMO.
basis of the first oxidation potentials (Table 1), the HOMO
energy levels are calculated to be -5.19, -5.22 and -5.26 eV for
p-TFT, mp-TFT and m-TFT, respectively.[38] It is noted that the
HOMO energy level is more stable with the decreased degree of
π-conjugation (EHOMO(p-TFT) < EHOMO(mp-TFT) < EHOMO(m-TFT)). This
change tendency agrees well with the calculation results.
According to the HOMO energy levels and the optical band-gaps,
the LUMOs of these compounds are evaluated to be -2.48 eV
(p-TFT), -2.34 eV (mp-TFT) and -2.19 eV (m-TFT).
Electrochemical Properties
Electroluminescent Properties
The electrochemical properties of p-TFT, mp-TFT and m-TFT
were investigated in CH2Cl2 solution by cyclic voltammetry (CV).
All compounds show several irreversible oxidation waves in the
range of 0-1.65 V (vs Fc/Fc+, EFc/Fc+ = 0.15 V, ESI†). On the
To further explore the effect of interconnection position on the
electroluminescent property, the devices based on p-TFT, mp-
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Figure 5. The molecular structure of the materials used in the device and the energy level diagram of the device.
Figure 6. EL spectra (a) and CIE (b) coordinates of the devices.
TFT or m-TFT with the configuration of ITO/PEDOT:PSS (30
voltages of 5.0 and 5.5 V respectively. In addition, the devices
based on mp- TFT and m-TFT show the inferior performance
with a maximum luminance of 4238 cd/m2 at 15 V (373 mA/cm2)
and 1241 cd/m2 at 14 V (353 mA/cm2), respectively. This result
can be explained by the increased energy barrier for electron
injection at the TmPyPB/dopant interface leading to an
unmatched LUMO energy level.
The current density-current efficiency (CE) and current
density-external quantum efficiency (EQE) characteristics of the
devices are shown in Figure 8. The maximum CE and EQE of
the OLED based on p-TFT are 6.2 cd/A and 2.3 %, respectively.
The efficiencies were drastically reduced to 2.0 cd/A (CE) and
1.2 % (EQE) for the mp-TFT based device and 0.7 cd/A (CE)
and 0.5 % (EQE) for the m-TFT based device. The EQE of the
p-TFT based device is 2 times and 4 times higher than that of
the mp-TFT and m-TFT based devices, respectively. Obviously,
it is clearly demonstrated that the interconnection position plays
a significant role on the device performance.
nm)/mCP:PVK:compounds (80:10:10, 30 nm)/TmPyPB (40
nm)/Liq (1 nm)/Al were fabricated. The molecular structure of the
host matrix and electronic transport material and the energy
level diagrams of the device are shown in Figure 5.
The electroluminescence (EL) spectra of the devices doped
with p-TFT, mp-TFT or m-TFT at 10 V are shown in Figure 6a.
All the devices display the emission spectra with broad and
structureless emission centered at 504 nm (λonset = 424 nm), 468
nm (λonset = 403 nm) and 455 nm (λonset = 387 nm) for p-TFT, mp-
TFT and m-TFT, respectively, suggesting that there is a
complete energy transfer from the host matrix to the dopant
(Figure 6a). The commission international de L'Eclairage (CIE)
coordinates of (0.23, 0.47), (0.16, 0.22) and (0.17, 0.18) (Figure
6b) are observed for the p-TFT, mp-TFT and m-TFT doped
devices, respectively. From the luminance-voltage-current
density (L-V-J) curves (Figure 7), the p-TFT based device
possesses a low turn-on voltage (a voltage for the luminance of
1 cd/m2) of 4 V with a maximum luminance of 10150 cd/m2 at 14
V (369 mA/cm2). Compared to the p-TFT based device, the mp-
TFT and m-TFT based devices give the relatively higher turn-on
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molecular engineering described in this research could pave the
way to the development of novel blue emitter featuring D-π-A
framework.
Experimental Section
Experimental Section
Materials and Measurement
4-bromoiodobenzene, 3-bromoiodobenzene, 2,7-dibromofluorenone, 4-
bromobenzonitrile and 3-bromobenzonitrile are commercial from Energy
Chemical Company Ltd. Other reagents were purchased from J&K
Chemical and Aladdin companies. All reactions were carried out under N2
atmosphere. Compound 2a, 2b, 3 and 5b were prepared via the previous
work.[22,31] 1H NMR and 13C NMR spectra were acquired using a Bruker
Dex-400 NMR instrument using CDCl3 as a solvent. Mass spectra (MS)
were recorded on a Bruker Autoflex MALDI-TOF instrument using
dithranol as a matrix. The UV-vis absorption and photoluminescence (PL)
spectra were measured with a Varian Cray 50 and Perkin-Elmer LS50B
luminescence spectrometer, respectively. Lifetimes were measured with
Edinburgh analytical instrument (FLS920 fluorescence spectrometer) in
degassed toluene at room temperature. Solutions of 9,10-
dibromoanthracene in ethanol (Φ=0.89) were used as a reference. The
equation Φs = Φr(ηs2ArIs/ηr2AsIr) was used to calculate the quantum yields.
The Φ in neat film was collected by EdinburghInstruments FLS980.
Thermogravimetric analysis (TGA) was carried out with a NETZSCH
STA449 from 25°C to 600°C at a 20°C/min heating rate under N2
atmosphere. Electrochemical property was evaluated by cyclic
voltammetry with three typical electrodes in degassed CH2Cl2 solution
with a rate of 100 mV/s. The CV system employed Bu4NPF6 as
electrolyte. Platinum disk is used as the working electrode, platinum wire
is regarded as the counter electrode and silver wire is used as the
reference electrode. Ferrocenium/ferrocen (Fc/Fc+) was used as the
internal standard compound.
Figure 7. Luminance-voltage-current density (L-V-J) characteristics of the
devices.
Devices fabrication and characterization
All devices employing p-TFT, mp-TFT and m-TFT as the dopant were
fabricated by solution-processed approach. In these OLEDs,
PEDOT:PSS was spin-coated onto ITO substrate, which is utilized as the
hole injection layer. The blend of mCP and PVK was used as the host
matrix. TmPyPB is the electron transporting layer with 40 nm thick. Liq
and Al are used as the composite cathode. Electroluminescent spectra
were recorded using an optical analyzer, Photo Research PR735. The
features of current density and brightness versus applied voltage were
simultaneously obtained by a Keithley 2420 and PR735. EQE was
calculated from the luminance, current density, and EL spectrum,
assuming a Lambertian distribution. The device configurations are as
follows: ITO/PEDOT:PSS (30 nm)/mCP:PVK:compounds (80:10:10, 30
nm)/TmPyPB (40 nm)/Liq (1 nm)/Al
Figure 8. Current density-current efficiency (a) and current density-external
quantum efficiency (b) characteristics of devices.
Conclusions
In summary, three star-shaped D-π-A isomers based on the
triazine, spirofluorene and triphenylamine units were
successfully designed and prepared. All target compounds
showed a good thermal stability. Through modification the
interconnection position among the building blocks, these
isomers can exhibit tunable emission colors from deep blue to
green in solution owing to a different degree of π-conjugation. In
addition, these compounds possessed clearly different HOMO
and LUMO distributions in the ground state and energy gap
evidenced by theory calculation and cyclic voltammetry. The
OLEDs employing these isomers as the emissive dopants were
fabricated, and the p-TFT based OLEDs offered a highest EQE
of 2.3 % and CE of 6.2 cd/A. Therefore, we believe that the
Synthesis of 5a
A mixture of 4a (1.2 g, 2.2 mmol) and bis(pinacolato)diboron (1.9 g, 7.3
mmol), CH3COOK (0.6 g, 6.6 mmol) and 1,1'-Bis(diphenylphosphino)
ferrocene palladiumdichloride (102 mg) were dissolved in 50 mL 1,4-
dioxane was refluxed for 24 h. After cooling to room temperature, the
mixture was poured into water and extracted with CH2Cl2 (3×20 mL). The
organic phase was collected and washed with water (3×20 mL), dried
with anhydrous Na2SO4. The solvent was removed under vacuum, and
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then the residue was purified by column chromatography with petroleum
ether (PE)/CH2Cl2 (1:1) as an eluent to get the compound 5a, white solid,
1.1 g, yield: 76%. 1H NMR (400 MHz, CDCl3) δ: 8.78 (d, J = 8 Hz, 6H),
8.03 (d, J = 8.4 Hz, 6H).
m-TFT: yellow powder, 0.21 g, yield : 42%. 1H NMR (500 MHz, CDCl3): δ
8.78 (s, 3H), 8.49 (d, J = 7.5 Hz, 3H), 7.97 (d, J = 7.5 Hz, 3H), 7.87 (dd, J
= 8.0 Hz, 16.5 Hz, 9H), 7.77 (d, J = 7.5 Hz, 3H), 7.63 (d, J = 7.5 Hz, 3H),
7.50-7.47 (m, 6H), 7.37 (t, J = 7.5 Hz, 6H), 7.12-7.02 (m, 27H), 6.88-6.78
(m, 27H), 3.79 (s, 18H). 13C NMR (101 MHz, CDCl3) δ: 171.50, 155.70,
150.12, 149.84, 149.16, 148.71, 141.94, 141.46, 141.29, 141.13, 140.64,
136.52, 131.33, 129.25, 129.03, 128.02, 127.93, 127.57, 127.29, 127.09,
126.47, 124.39, 122.88, 120.57, 120.41, 120.16, 120.01, 119.72, 114.74,
66.21, 55.60. TOF-MS (EI, m/z): [M+] cal. for C156H108N6O6 2161.836,
found 2161.073.
General synthesis procedure for compound 6a and 6b
To a dry round bottom flask was added compound 2a or 2b (1 eq),
compound 3 (1 eq), tetrakis(triphenylphosphine)palladium (0.04 eq),
potassium carbonate solution (2 M, 15 mL) and THF (50 mL). The
mixture was refluxed for 24 h under nitrogen. After cooling to room
temperature, the mixture was poured into water and extracted with
CH2Cl2 (3×20 mL). The organic phase was washed with water for three
times and dried with anhydrous Na2SO4. The solvent was removed via
rotary evaporator under vacuum, and then the residue was purified by
column chromatography with PE/CH2Cl2 (4:1) as an eluent to get the
compound 6a and 6b.
Acknowledgements
The authors thank Mr. Jianlei Han from National Center for Nanoscience
and Technology for the help of measurement of fluorescence quantum
yield. This work is supported by the National Natural Science Foundation
of China (Nos. 21202139, 51473140, 61575146 and 51273168), the
Program for Innovative Research Cultivation Team in University of
Ministry of Education of China (1337304), the Open Fund of the State
Key Laboratory of Luminescent Materials and Devices (South China
University of Technology) (2015-skllmd-08), Natural Science Foundation
of Hunan (2015JJ2042).
6a: light green solid, 0.71 g, yield: 52%. 1H NMR (400 MHz, CDCl3) δ:
7.84 (d, J = 7.2 Hz, 4H), 7.69 (d, J = 7.6 Hz 1H), 7.56 (s, 1H), 7.49-7.36
(m, 6H), 7.13 (t, J = 7.2 Hz, 4H), 6.99-6.76 (m, 10H), 3.77 (s, 6H). TOF-
MS (EI, m/z): [M+] cal. for C45H32BrNO2 698.653, found 699.328.
6b: light green powder, 0.65 g, yield : 48%. 1H NMR (400 MHz, CDCl3) δ:
7.84 (d, J = 9.2 Hz, 2H), 7.78 (d, J = 6.4 Hz 1H), 7.68 (d, J = 6.8 Hz, 1H),
7.47-7.38 (m, 4H), 7.11-7.01(m, 8H), 6.83-6.75 (m, 10H) 3.79 (s, 6H).
TOF-MS (EI, m/z): [M+] cal. for C45H32BrNO2 698.653, found 699.174.
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/asia.201xxxxxx.
Keywords: Star-shaped D-π-A molecules • interconnection
position • 1,3,5-triphenyltriazine • Triphenylamine • photophysical
property
General Synthesis procedures for p-TFT, mp-TFT and m-TFT
A
mixture of compound 6a or 6b (1 eq), 5a or 5b (1 eq),
tetrakis(triphenylphosphine)palladium (0.04 eq), potassium carbonate
solution (2 M, 10 mL) and THF (50 mL) was refluxed for 24 h under
nitrogen. After cooling to room temperature, the mixture was poured into
water and extracted with CH2Cl2 (3×10 mL). The organic phase was
washed with water for three times and dried with anhydrous Na2SO4. The
solvent was removed via rotary evaporator under vacuum, and then the
residue was purified by column chromatography to get the target
compounds.
[1] A. C. Grimsdale, K. L. Chan, R. E. Martin, P. G. Jokisz, A. B. Holmes,
Chem. Rev. 2009, 109, 897-1091.
[2] L. Duan, J. Qiao, Y. D. Sun, Y. Qiu, Adv. Mater. 2011, 23, 1137-1144.
[3] S. Ellinger, K. R. Graham, P. J. Shi, R. T. Farley, T. T. Steckler, R. N.
Brookins, P. Taranekar, J. J. Mei, L. A. Padilha, T. R. Ensley, H.-H. Hu,
S. Webster, D. J. Hagan, E. W. V. Stryland, K. S. Schanze, J. R.
Reynolds, Chem. Mater. 2011, 23, 3805-3817.
[4] X. Qian, Y. Z. Zhu, J. Song, X. P. Gao, J. Y. Zheng, Org. Lett. 2013, 15,
6034-6037.
p-TFT: yellow solid, 0.24 g, yield: 48%. 1H NMR (500 MHz, CDCl3) δ:
8.63 (d, J = 8.0 Hz, 6H), 7.94-7.87 (m, 12H), 7.72 (d, J = 8.0 Hz, 3H),
7.59 (d, J = 8.0 Hz, 9H), 7.39 (t, J = 7.5 Hz, 6H), 7.24 (d, J = 8.0 Hz, 6H),
7.13 (t, J = 7.5 Hz, 6H), 7.03-7.0 (m, 15H), 6.89-6.83 (m, 15H), 6.79 (d, J
= 9.0 Hz, 12H), 3.78 (s, 18H). 13C NMR (101 MHz, CDCl3) δ: 171.14,
155.89, 150.08, 149.97, 148.78, 148.17, 141.93, 141.71, 140.93, 139.86,
139.80, 135.06, 132.91, 129.31, 128.06, 127.95, 127.59, 127.24, 126.55,
126.35, 124.39, 122.79, 122.15, 120.83, 120.56, 120.42, 120.21, 114.75,
66.22, 55.61. TOF-MS (EI, m/z): [M+] cal. for C156H108N6O6 2161.836,
found 2161.275.
[5] J. B. Yang, P. Ganesan, J. Teuscher, T. Moehl, Y. J. Kim, C. Yi, P.
Comte, K. Pei, T. W. Holcombe, M. K. Nazeeruddin, J. L. Hua, S. M.
Zakeeruddin, H. Tian, M. Grätzel, J. Am. Chem. Soc. 2014, 136 , 5722-
5730.
[6] S. H. Zeng, L. X. Yin, C. Y. Ji, X. Y. Jiang, K. C. Li, Y. Q Li, Y. Wang,
Chem. Commun. 2012, 48, 10627-10629.
[7] T. D. Kim, K. S. Lee. Rapid Commun. 2015, 36, 943-958.
[8] A. Lv, M. Stolte, F. Würthner, Angew. Chem. Int. Ed. 2015, 54, 10512-
10515.
[9] Y. Y. Gong, Y. Q. Tan, J. Liu, P. Lu, C. F Feng, W. Z. Yuan, Y. W. Lu, J.
Z. Sun, G. F. He, Y. M. Zhang, Chem. Commun. 2013, 49, 4009-4011.
[10] X. Y. Tang, Q. Bai, Q. M. Peng, Y. Gao, J. Y. Li, Y. L. Liu, L. Yao, P. Lu,
B. Yang, Y. G. Ma, Chem. Mater. 2015, 27, 7050-7057.
[11] S. Sasaki, Y. Niko, K. Igawa, G. Konishi, RSC Adv. 2014, 4, 33474-
33477.
mp-TFT: yellow powder, 0.24 g, yield: 46%. 1H NMR (500 MHz, CDCl3):
δ 8.79 (s, 3H), 8.50 (d, J = 8.0 Hz, 3H), 7.98 (d, J = 8.0 Hz, 3H), 7.93 (d,
J = 7.5 Hz, 3H), 7.85 (d, J = 8.0 Hz, 6H), 7.77 (dd, J = 1.0 Hz, 7.5 Hz,
3H), 7.61 (dd, J = 8.0 Hz, 13.5 Hz, 6H), 7.47 (t, J = 7.5 Hz, 3H), 7.36 (t, J
= 7.5 Hz, 6H), 7.25 (t, J = 8.5 Hz, 3H), 7.11 (t, J = 7.5 Hz, 6H), 7.05-7.0
(m, 15H), 6.91 (s, 3H), 6.86 (t, J = 7.5 Hz, 12H), 6.79 (t, J = 8.5 Hz, 12H),
3.78 (s, 18H). 13C NMR (101 MHz, CDCl3): δ 171.48, 155.87, 150.07,
149.96, 148.85, 148.13, 141.93, 141.47, 141.29, 140.94, 140.34, 139.96,
136.51, 132.96, 128.99, 128.03, 127.90, 127.59, 127.28, 126.52, 124.42,
122.82, 122.21, 120.86, 120.46, 120.17, 114.74, 66.23, 55.60. TOF-MS
(EI, m/z): [M+] cal. for C156H108N6O6 2161.836, found 2161.233.
[12] D. Thirion, J. R. Berthelot, L. Vignau, C. Poriel, Org. Lett. 2011, 13,
4418-4421.
[13] T. Matulaitis, N. Kostiv, J. V. Grazulevicius, L. Peciulyte, J. Simokaitiene,
V. Jankauskas, B. Luszczynsk, J. Ulanski, Dyes and Pigments. 2016,
127, 45-58.
[14] J. Ye, Z. Chen, M. K. Fung, C. J. Zheng, X. M. Ou, X. H. Zhang, Y. Yuan,
C. S. Lee, Chem. Mater. 2013, 25, 2630-2637.
For internal use, please do not delete. Submitted_Manuscript

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FULL PAPER
[15] A. L. Kanibolotsky, I. F. Perepichka, P. J. Skabara, Chem. Soc. Rev.
2010, 39, 2695-2728.
[27] M. Yu, S. Wang, S. Shao, J. Ding, L. Wang, X. Jing, F. Wang, J. Mater.
Chem. C. 2015, 3, 861-869.
[16] J. L. Wang, Z. M. Tang, Q. Xiao, Y. G. Ma, J. Pei, Org. Lett. 2009, 11,
863-866.
[28] J. V. Grazulevicius, P. Strohriegl, J. Pielichowski, K. Pielichowski,
Progress in Polymer Science. 2003, 28, 1297-1353.
[29] K. Brunner, A. V. Dijken, H. Börner, J. J. A. M. Bastiaansen, N. M. M.
Kiggen, B. M. W. Langeveld, J. Am. Chem. Soc. 2004, 126, 6035-6042.
[30] J. F. Morin, M. Leclerc, D. Adès, A. Siove, Rapid Commun. 2005, 26,
761-778.
[17] N. A. Kukhta, J. Simokaitiene, D. Volyniuk, J. Ostrauskaite,J. V.
Grazulevicius, G. Juska, V. Jankauskas, Synthetic Metals. 2014, 195,
266-275.
[18] L. Zou, Z. J. Liu, X. B. Yan, Y. Liu, Y. Fu, J. Liu, Z. L. Huang, X. G. Chen,
J. G. Qin, Eur. J. Org. Chem. 2009, 32, 5587-5593.
[19] N. A. Kukhta, D. Volyniuk, J. V. Grazulevicius, G. Juska, J. Phys. Chem.
C 2016, 120, 1208-1217.
[31] H. Tanaka, K. Shizu, H. Nakanotani, C. Adachi, J. Phys. Chem. C 2014,
118, 15985-15994.
[32] M. Leclerc, Polymer Chem. 2001, 39, 2867-2873.
[33] L. Zhao, S. Wang, S. Shao, J. Ding, L. Wang, X. Jing, F. Wang, J. Mater.
Chem. C. 2015, 3, 8895-8903.
[20] H. L. Zhong, H. Lai, Q. Fang, J. Phys. Chem. C 2011, 115, 2423-2427.
[21] J. Pang, Y. Tao, S. Freiberg, X. P. Yang, M. D'Iorio, S. N. Wang, J.
Mater. Chem. 2002, 12, 206-212.
[34] J. Pei, J. Ni, X.-H. Zhou, X. Y. Cao, Y. H. Lai, J. Org. Chem. 2002, 67,
4924-4936.
[22] B. Huang, Z. H. Yin, X. X. Ban, W. Jiang, Y. Dai, J. Y. Zhang, Y. Y. Liu,
Y. P. Yang, Y. M. Sun, Dyes and Pigments. 2015, 117, 141-148.
[23] H. Tanaka, K. Shizu, H. Miyazaki, C. Adachi, Chem. Commun. 2012, 48,
11392-11394.
[35] M. Kim, S. K. Jeon, S. H. Hwang, S. S. Lee, E. Yu, J. Y. Lee, Chem.
Commun. 2016, 52, 339-342.
[36] T. Imagawa, S. Hirata, K. Totani, T. Watanabe, M. Vacha, Chem.
Commun. 2015, 51, 13268-13271.
[24] C. Ego, A. C. Grimsdale, F. K. Uckert, G. Yu, G. Srdanov, K. Müllen, Adv.
Mater. 2002, 14, 809-811.
[37] R. P. DeToma, D. O. Cowan, J. Am. Chem. Soc. 1975, 97, 3283-3291.
[38] Y. Wang, L. Chen, R. M. El-shishtawy, S. G. Aziz, K. Müllen, Chem.
Commun. 2015, 50, 11540-11542.
[25] A. Cravino, S. Roquet, O. Alévêque, P. Leriche, P. Frère, J. Roncali,
Chem. Mater. 2006, 18, 2584-2590.
[26] B. Chen, J. Ding, L. Wang, X. Jing, F. Wang, Chem. Commun. 2012, 48,
8970-8972.
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Table of Contents
Three star-shaped D-π-A
isomers based on 1,3,5-
triphenyl-2,46-triazine, spiro-
fluorene and triphenylamine
moieties, p-TFT, mp-TFT and
m-TFT, were synthesized and
Yafei Wang†#§*, Wanhui Liu†,
Jiyong Deng‡, Guohua Xie△*,
Yuanwei Liao†, Zuoming Qu†,
Hua Tan†, Yu Liu†, Weiguo Zhu#
Engineering
Interconnection Position of
Star-Shaped D-π-A Molecules
The
prepared
engineering
interconnection
via
elaborately
the
position
among the building block
units. The structure-property
relationship of these isomers
was systematically explored
by experiment and theory
calculation.
Based
Spirofluorene
Triphenylamine Moieties for
Color Tuning from Deep blue
to Green
on
Triazine,
and
For internal use, please do not delete. Submitted_Manuscript