Star-shaped triphenylamine terminated difluoroboron β-diketonate complexes: Synthesis, photophysical and electrochemical properties

Article abstract of DOI:10.1016/j.tet.2014.03.069

Two new star-shaped difluoroboron β-diketonate complexes (TBC) ₃Ph and (TBF)₃Ph, in which the terminal groups of triphenylamine functionalized difluoroboron β-diketonates were bridged by carbazole or fluorene to the core of 1,3,5-benzene, have been synthesized. It was found that they gave high molar extinction coefficients, meaning strong light-harvesting ability, and emitted intense yellow light with fluorescence quantum yields (Φ_F) of 0.73 and 0.67 for (TBC)₃Ph and (TBF)₃Ph, respectively, in toluene as well as red light in solid states with Φ_F of 0.36 and 0.27, respectively. The electrochemical behaviors suggested that they had considerably higher electron affinities than tris(8-hydroxyquinoline)aluminum (AlQ₃), which indicated that they could be used as electron-transporting materials besides emitting materials.

Full text of DOI:10.1016/j.tet.2014.03.069

Tetrahedron 70 (2014) 3935e3942
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Star-shaped triphenylamine terminated difluoroboron b-diketonate
complexes: synthesis, photophysical and electrochemical properties
*
Chong Qian, Guanghui Hong, Mingyang Liu, Pengchong Xue, Ran Lu
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new star-shaped difluoroboron
minal groups of triphenylamine functionalized difluoroboron
b
-diketonate complexes (TBC)3Ph and (TBF)3Ph, in which the ter-
-diketonates were bridged by carbazole or
Received 30 December 2013
Received in revised form 14 March 2014
Accepted 20 March 2014
b
fluorene to the core of 1,3,5-benzene, have been synthesized. It was found that they gave high molar
extinction coefficients, meaning strong light-harvesting ability, and emitted intense yellow light with
fluorescence quantum yields (FF) of 0.73 and 0.67 for (TBC)3Ph and (TBF)3Ph, respectively, in toluene as
well as red light in solid states with FF of 0.36 and 0.27, respectively. The electrochemical behaviors
suggested that they had considerably higher electron affinities than tris(8-hydroxyquinoline)aluminum
(AlQ3), which indicated that they could be used as electron-transporting materials besides emitting
materials.
Available online 28 March 2014
Keywords:
Star-shaped macromolecules
Triphenylamine
Difluoroboron b-diketonate
Photophysical
Ó 2014 Elsevier Ltd. All rights reserved.
Electrochemical
1. Introduction
triphenylamine functionalized difluoroboron b-diketonate com-
plexes, which can be used as fluorescent sensory materials for
Four-coordinate organoboron complexes have been extensively
studied for various applications in biological sensing and imaging,
detecting organic amines vapor with high sensitivity and fast re-
sponse rate.12 On the other hand, star-shaped
p-conjugated sys-
electroluminescent devices, etc.1e3 Among them, difluoroboron
b
-
tems have attracted considerable attention recently due to their
unique properties, such as suppressing the quenching of fluores-
cence in solid state, improving the light-harvesting ability and so
on.13 They have exhibited potential applications in photovoltaic
cells,14 organic light-emitting diodes,15 nonlinear optics,16,17 and
field-effect transistors.18 However, to the best of our knowledge,
reports on the construction of star-shaped molecules based on
diketonate complexes have attracted much interest because of their
intriguing properties, such as high quantum yields, large molar
extinction coefficients, strong emission in solid state, high electron
affinities, and sensitivity to the surrounding medium.4e7 Therefore,
they have been employed in various fields, including two-photon
absorption materials,8 mechanochromic luminescent materials,9
near-IR probes,10 and organic field-effect transistors.11 For exam-
difluoroboron
gain novel difluoroboron b
b
-diketone derivatives are rare. Herein, in order to
-diketone complexes with enhanced
ple, Fraser’s group has synthesized a series of difluoroboron
b
-
diketonate complexes and investigated their reversible mechano-
light-harvesting ability and intensive emission in solution as well as
in the solid state, we designed new star-shaped macromolecules
(TBC)3Ph and (TBF)3Ph (Scheme 1), in which the terminal groups of
chromic fluorescence in solid state.9 Perry et al. have developed
two-photon absorption materials based on difluoroboron b-diket-
onate complexes, which can be used to photoreduce silver ions.8b
Additionally, the formation of stable six-membered boron-chelat-
triphenylamine functionalized difluoroboron b-diketonates were
bridged by carbazole or fluorene to the core of 1,3,5-benzene. It was
found that (TBC)3Ph and (TBF)3Ph gave high molar extinction co-
efficients of 2.90ꢀ105 Mꢁ1 cmꢁ1 and 3.11ꢀ105 Mꢁ1 cmꢁ1 in THF,
respectively, meaning strong light-harvesting ability. Meanwhile,
(TBC)3Ph and (TBF)3Ph not only could emit intense yellow light in
toluene with the fluorescence quantum yields (FF) of 0.73 and 0.69,
respectively, but also emit strong red light in solid states with FF of
0.36 and 0.27, respectively. The electrochemical data suggested that
they had considerably higher electron affinities than tris(8-
hydroxyquinoline)aluminum (AlQ3), indicating they might be
used as electron-transporting materials besides emitting materials.
ing ring in difluoroboron b-diketonate complexes can inhibit the
nonradiative dissipation through OeH stretching modes from
tautomerization between ketone and enol forms, and may extend
the
p-conjugation of the molecules, which would favor the mo-
lecular assembly via
pep
interaction. Recently, our group reported
the facile fabrication of low-dimensional nanostructures from
* Corresponding author. Tel.: þ86 431 88499179; fax: þ86 431 88923907; e-mail
address: luran@mail.jlu.edu.cn (R. Lu).
0040-4020/$ e see front matter Ó 2014 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2014.03.069

3936
C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
Scheme 1. Molecular structures of (TBC)3Ph and (TBF)3Ph.
2. Results and discussion
Suzuki coupling reaction condition in a yield of 35%. Finally, 3,30,300-
(benzene-1,3,5-triyltris(9,9-dioctyl-9H-fluorene-7,2-diyl))tris(1-
(4-(diphenylamino)phenyl)propane-1,3-dione) was prepared via
the Claisen condensation reaction between methyl 4-(diphenyla-
mino)benzoate and compound 6, and it complexed with boron
trifluorideediethyl etherate directly to give (TBF)3Ph in a yield of
12% over two steps. The new compounds were characterized by 1H
NMR, 13C NMR, MALDI-TOF mass spectrometry, and C, H, N ele-
mental analyses. And two complexes are air-stable and show good
solubility in THF, CH2Cl2, CHCl3, DMSO, ethyl acetate, and aromatic
solvents (such as benzene and toluene), while they have poor sol-
ubility in alcohols (such as ethanol and methanol) and aliphatic
hydrocarbon solvents (such as petroleum ether and n-hexane).
2.1. Synthesis and characterizations
The synthetic routes for the star-shaped triphenylamine termi-
nated difluoroboron
b-diketonate complexes (TBC)3Ph and
(TBF)3Ph were shown in Scheme 2. Firstly, compound 2 was syn-
thesized via FriedeleCrafts acylation reaction of compound 1 with
acetyl chloride in a yield of 52%. Then, the Suzuki coupling reaction
between compound
2 and 1,3,5-tris(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)benzene gave compound 3 in a yield of 27%.
The Claisen condensation between methyl 4-(diphenylamino)
benzoate and compound 3 in the presence of sodium hydride in
anhydrous toluene yielded 3,30,300-(6,60,600-(benzene-1,3,5-triyl)
tris(9-dodecyl-9H-carbazole-6,3-diyl))tris(1-(4-(diphenylamino)
phenyl)propane-1,3-dione), which was not further purified and
complexed with boron trifluorideediethyl etherate directly in an-
hydrous CH2Cl2, affording (TBC)3Ph in a yield of 18%. Similarly,
compound 5 was gained from compound 4 through FriedeleCrafts
acylation reaction, and it was transferred into compound 6 under
2.2. UVevis absorption and fluorescent emission spectra
The UVevis absorption and the fluorescence emission spectra of
(TBC)3Ph and (TBF)3Ph in toluene and in the films were shown in
Fig. 1, and the corresponding photophysical data were summarized
in Table 1. It was clear that (TBC)3Ph showed several obvious
Scheme 2. Synthetic routes for complexes (TBC)3Ph and (TBF)3Ph.

C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
3937
Fig. 1. Normalized UVevis absorption (a) and fluorescence emission (b, lex¼486 nm)
spectra of (TBC)3Ph (blue) and (TBF)3Ph (red) in toluene (solid, 2.0ꢀ10ꢁ6 M) and in the
films (dashed).
Fig. 2. Normalized UVevis absorption (a) and fluorescence emission spectra (b,
lex¼486 nm) of (TBC)3Ph in different solvents (2.0ꢀ10ꢁ6 M).
gradually with increasing the polarity of the solvents, and it
reached 497 nm in DMF (Fig. 2a). These results suggest an excited
state with a larger dipole moment than that in the ground state.19
Moreover, the fluorescence emission bands of (TBC)3Ph red-
shifted significantly with increasing the solvent polarity, accom-
panying with the broaden of the emission. For example, the emis-
sion maximum of (TBC)3Ph in toluene appeared at 551 nm (Fig. 1b),
which red-shifted to 615 nm in DMF (Fig. 2b). Therefore, such
significant red-shift and the broaden of the emission band with
increasing the polarity of the solvents indicated the ICT emission
feature of (TBC)3Ph.12 It should be noted that (TBC)3Ph gave high
Table 1
Photophysical data of (TBC)3Ph and (TBF)3Ph in different solvents
Dnstb/cmꢁ1
FF
a
c
Complex
Solvents
lmabasx/nm (
3
)
lem/nm
max
(TBC)3Ph
Toluene
1,4-Dioxane
THF
Chloroform
DCM
486 (2.49)
486 (2.81)
488 (2.90)
496 (3.07)
496 (2.85)
497 (2.77)
490 (2.76)
489 (3.01)
490 (3.11)
496 (2.14)
497 (3.05)
500 (3.01)
551
556
580
588
611
615
566
588
617
622
648
664
2427
2590
3250
3154
3794
4148
2740
3443
4201
4084
4689
4939
0.73
0.69
0.33
0.51
0.15
0.02
0.67
0.51
0.08
0.24
0.03
d
DMF
(TBF)3Ph
Toluene
1,4-Dioxane
THF
Chloroform
DCM
molar extinction coefficient (
3
max) of 2.90ꢀ105 Mꢁ1 cmꢁ1 in THF,
which was nearly three times as high as our previously reported
DMF
similar
difluoroboron
b
-diketonate
complex
BDOBC16
a
ꢀ105 Mꢁ1 cmꢁ1
.
(1.0ꢀ105 Mꢁ1 cmꢁ1 in THF).12d Therefore, the star-shaped structure
b
c
Dnst
¼
nabs nem.
ꢁ
can remarkably improve the light-harvesting ability of difluor-
Fluorescence quantum yield determined by a standard method with Rhodamine
oboron
b-diketonate complex, which is of importance in light-
6G in water (FF¼0.75, lex¼488 nm) as reference.
harvesting systems.14 On the other hand, the absorption and
emission behaviors of (TBF)3Ph were similar to those of (TBC)3Ph.
absorption bands in toluene from 290 nm to 600 nm (Fig. 1a). The
bands appeared at 290 nm and 342 nm were due to the electronic
transitions of triphenylamine and carbazole units, the one at ca.
The
3
for (TBF)3Ph reached 3.11ꢀ105 Mꢁ1 cmꢁ1 in THF. The
max
maximal absorption and emission bands for (TBF)3Ph emerged at
490 nm and 566 nm in toluene, respectively, giving a little red-shift
compared with those for (TBC)3Ph (486 nm and 551 nm, re-
400 nm was assigned to the
pep* transition of the molecule, and
the band emerged at 486 nm was ascribed to the intermolecular
charge transfer (ICT) transition, which could be supported by the
solvent-dependent absorption and fluorescence emission spectral
changes (Fig. 2 and Table 1). For example, the maximal absorption
band of (TBC)3Ph located at 486 nm in toluene red-shifted
spectively) due to the larger molecular p-conjugation of (TBF)3Ph
bearing the linker of 2,7-fluorene than that in (TBC)3Ph bearing the
spacer of 3,6-carbazole.20 We also confirmed that the above bands
also resulted from ICT transition (Figs. 1 and 2, Fig. S1, and Table 1).
In addition, it should be noted that the maximal absorption of

3938
C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
Table 2
(TBC)3Ph and (TBF)3Ph in the films became broad and showed
Electrochemical and theoretical calculated data
a red-shift of 14 nm and 10 nm, respectively, compared with those
HOMOb
(eV)
LUMOb
(eV)
1/2a
c
in toluene on account of the aromatic
p-stacking interaction in
Complex
E
Eg
HOMOd
(eV)
LUMOd
(eV)
red
(V)
(eV)
solid states, and the smaller red-shift of the absorption band for
(TBF)3Ph compared with that in (TBC)3Ph might result from
a better site-isolation effect of the branched alkyl group in fluo-
rene.21 Meanwhile, the emission band of (TBF)3Ph red-shifted to
632 nm in the film from 566 nm in toluene (Dl¼66 nm), and that of
(TBC)3Ph red-shifted to 619 nm in the film from 551 nm in toluene
(TBC)3Ph
(TBF)3Ph
ꢁ1.59
ꢁ1.48
ꢁ5.48
ꢁ5.55
ꢁ3.21
ꢁ3.32
2.27
2.23
ꢁ5.32
ꢁ5.57
ꢁ2.42
ꢁ2.76
a
1/2
E
red
(V)¼onset reduction potential, Potentials are given against ferrocenium/
ferrocene.
b
1/2
Calculated using the empirical equation: LUMO¼ꢁ(4.8þE
)
and
red
EHOMO¼ELUMOꢁEg.
(Dl¼68 nm), further indicating the better site-isolation effect in
c
Estimated from the onset of the absorption spectra (Eg¼1240/lonset).
d
star-shaped (TBF)3Ph. Furthermore, the fluorescence quantum
yields of the two complexes in different solvents were determined
using Rhodamine 6G as standard. We found that the FF values of
(TBC)3Ph and (TBF)3Ph were 0.73 and 0.67 in toluene, respectively,
meaning that they were strong emissive in non-polar solvents, and
they decreased with the increasing the solvent polarity (Table 1)
because of the decreased radiative decay process. Moreover, the
fluorescence quantum yields of (TBC)3Ph and (TBF)3Ph in solid
states were measured using an integrating sphere, and they were
0.36 and 0.27, respectively, suggesting strong emissive in solid
states. Therefore, the strong emission for the star-shaped difluor-
Obtained from quantum chemical calculation using DFT/B3LYP/6-31G.
2.4. Theoretical calculations
To gain an insight into the photophysical and electrochemical
properties of these two star-shaped complexes at the molecular
level, density functional theory (DFT) was used to calculate the
electronic structures and time-dependent DFT (TD-DFT) was
adopted to investigate the electronic transitions from ground to
excitation states. All calculations were performed at B3LYP/6-31G
level with the Gaussian 09W program package.25 Fig. 4 showed
the plots of molecular orbitals involved in the electronic transi-
oboron b-diketonate in solid states made it possible to be applied as
emitting materials in organic light-emitting diodes.
tions of (TBC)3Ph. In the optimized structure of (TBC)3Ph, the
p-
electrons in HOMO (highest occupied molecular orbital) and
HOMO-1 were mainly delocalized over the triphenylamine and
carbazole units, and those in HOMO-2 were mainly delocalized
over the triphenylamine unit, while LUMO (lowest unoccupied
molecular orbital), LUMOþ1 and LUMOþ2 were mainly delo-
2.3. Electrochemical properties
The electrochemical behaviors were investigated by cyclic vol-
tammetry. It was clear that (TBC)3Ph and (TBF)3Ph gave one well-
defined reversible reduced peak with half-wave potential (E1re/2d) of
calized over difluoroboron
b-diketone moieties. Similarly, the
ꢁ1.59 and ꢁ1.48 V versus ferrocenium/ferrocene (Fig. 3). Compared
LUMO, LUMOþ1, and LUMOþ2 of (TBF)3Ph were also mainly
delocalized over the acceptor of difluoroboron -diketone moiety
(Fig. 5). However, the -electron in the HOMO, HOMO-1, and
1/2
with (TBF)3Ph, the E of (TBC)3Ph showed a slight negative shift
red
b
due to the electron-donating effect of carbazole. Nonetheless, they
had considerably higher electron affinities than AlQ3 (ca. ꢁ2.30 V in
1/1 acetonitrile/benzene22), so they might have potential applica-
tions as electron-transport materials.23 The redox potential of Fc/
Fcþ, which possesses an absolute energy level of 4.8 eV relative to
the vacuum level for calibration, is located at 0.22 eV in our case.
Therefore, the LUMO energy levels of (TBC)3Ph and (TBF)3Ph were
calculated to be ꢁ3.21 eV and ꢁ3.32 eV with regard to ferrocene.24
Because no clear oxidation waves were observed, the HOMO energy
levels were deduced to be ꢁ5.48 eV and ꢁ5.55 eV from LUMO
energy levels and energy gaps determined by the onset of their
absorption spectra. The corresponding data were summarized in
Table 2.
p
HOMO-2 of (TBF)3Ph was mainly delocalized over triphenylamine
units except for fluorene unit due to its weaker electron donating
ability than carbazole in (TBC)3Ph. On the other hand, the elec-
tronic transition bands of (TBC)3Ph and (TBF)3Ph calculated by
TD-DFT were listed in Table 3. For (TBC)3Ph, we could find two
calculated electronic transition bands at 484.4 nm and 482.8 nm
from Fig. S2, which originated from several transitions of HOMO/
HOMO-2 to LUMO, HOMO-1 to LUMOþ1, and HOMO/HOMO-1/
HOMO-2 to LUMOþ2. Moreover, we deduced that the maximum
absorption band at 486 nm of (TBC)3Ph (in toluene) detected in
UVevis absorption spectrum corresponded to the above calculates
ones. Combined with the characters of HOMO-2, HOMO-1, HOMO,
LUMO, LUMOþ1, LUMOþ2, the absorption at 486 nm could be
assigned to ICT transition.26 Similarly, the absorption band at
490 nm of (TBF)3Ph in toluene was also relevant to the two cal-
culated bands at 494.4 nm and 493.5 nm (Fig. S3) coming from ICT
transitions. Therefore, the maximum absorption of (TBC)3Ph and
(TBF)3Ph resulted from an ICT transition, which was consistent
with the results of UVevis absorption and fluorescent
emission.5,27,28
3. Conclusions
In summary, we synthesized novel star-shaped difluoroboron
diketonate complexes (TBC)3Ph and (TBF)3Ph, in which the ter-
minal groups of triphenylamine functionalized difluoroboron
b-
b
-
diketonates were bridged by carbazole or fluorene to the core of
1,3,5-benzene. It was found that they gave high molar extinction
coefficients, for example, the
3
of (TBF)3Ph reached
max
3.11ꢀ105 Mꢁ1 cmꢁ1 in THF, which was higher than other reported
difluoroboron
b-diketonate complexes and meant strong light-
harvesting ability of the synthesized star-shaped macromolecules.
Fig. 3. Cyclic voltammograms of (TBC)3Ph and (TBF)3Ph in CH2Cl2.
Meanwhile, (TBC)3Ph and (TBF)3Ph emitted intense yellow light in

C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
3939
Fig. 4. The molecular orbital surfaces in the optimized ground-state structure for (TBC)3Ph.
Fig. 5. The molecular orbital surfaces in the optimized ground-state structure for (TBF)3Ph.
toluene with FF of 0.73 and 0.67, respectively, and strong red light
emitting in solid states was also detected for (TBC)3Ph and
(TBF)3Ph with FF of 0.36 and 0.27, respectively. The electrochemical
data illustrated that they had considerably higher electron affinities
than AlQ3, which indicated that they could be used as electron-
transporting materials. Therefore, the two difluoroboron -diket-
onate complexes (TBC)3Ph and (TBF)3Ph might have potential
b
applications as electron-transporters and emitting materials.

3940
C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
Table 3
cooling, the mixture was poured into water and extracted with
Main orbital transitions calculated with TD-DFT
dichloromethane for three times. Then the organic phase was
combined and dried over anhydrous Na2SO4. Removing the solvent
under reduced press, the residue was purified by column chro-
matography (silica gel, CH2Cl2/petroleum ether, v/v¼2/1) to give
a white solid (4.60 g). Yield: 52%. Mp: 104.0e106.0 ꢂC. 1H NMR
Complex
labsa/nm
lcalcdb/nm
fc
Composition (%)d
(TBC)3Ph
486
484.4
2.1102
H/L (35)
H-1/Lþ1 (21)
H-2/L (21)
H/Lþ2 (32)
H-1/Lþ1 (24)
H-1/Lþ2 (16)
H-2/Lþ2 (6)
H/L (6)
H/Lþ2 (34)
H-2/L (24)
H/L (13)
H/Lþ1 (10)
H-1/Lþ1 (8)
H-1/Lþ1 (32)
H-2/L (22)
H-1/Lþ2 (16)
H-2/Lþ1 (10)
H/Lþ2 (7)
482.8
494.2
493.5
1.5531
1.6190
2.1576
(500 MHz, CDCl3, ppm):
d
8.68 (d, J¼1.5 Hz, 1H), 8.26 (d, J¼2.0 Hz,
1H), 8.16e8.13 (m, 1H), 7.60e7.57 (m, 1H), 7.40 (d, J¼8.5 Hz, 1H),
7.31 (d, J¼8.5 Hz, 1H), 4.29 (t, J¼7.5, 7.0 Hz, 2H), 2.72 (s, 3H),
1.88e1.82 (m, 2H), 1.36e1.22 (m, 18H), 0.87 (t, J¼7.0, 7.0 Hz, 3H)
(Fig. S4). 13C NMR (100 MHz, CDCl3, ppm):
d 197.4, 143.4, 139.7,
(TBF)3Ph
490
129.1, 126.9, 124.9, 123.4, 122.1, 121.5, 112.8, 110.7, 108.7, 43.5, 31.9,
29.5, 29.3, 28.9, 27.2, 26.6, 22.7, 14.1 (Fig. S5). Elemental analysis for
C
26H34BrNO, calcd: (%) C, 68.41; H, 7.51; N, 3.07. Found: (%) C, 68.23;
H, 7.65; N, 3.10. MALDI-TOF MS, m/z (%): calcd for 456.2 [MþH]þ,
458.2 [MþH]þ, found: 456.7 (100) [MþH]þ, 458.7 (100) [MþH]þ
(Fig. S6).
4.2.2. 1,10,100-(6,60,600-(Benzene-1,3,5-triyl)tris(9-dodecyl-9H-carba-
zole-6,3-diyl))triethanone (3). A mixture of 1,3,5-tris(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)benzene (0.20 g, 0.44 mmol),
compound 2 (0.78 g, 1.71 mmol), and K2CO3 (0.60 g, 4.4 mmol) in
distilled water (20 mL) and toluene (20 mL) was charged and
bubbled by nitrogen for 15 min, then Pd(PPh3)4 (20 mg) was added.
The mixture was refluxed for 24 h under nitrogen. After cooling to
room temperature, the mixture was extracted with dichloro-
methane for three times. Then the organic phase was combined
and dried over anhydrous Na2SO4. Removing the solvent under
reduced press, the residue was purified by column chromatography
(silica gel, petroleum ether/ethyl acetate, v/v¼3/1) to give a light
yellow oil (0.14 g). Yield: 27%. 1H NMR (500 MHz, CDCl3, ppm):
a
Experimental maximum absorption in toluene.
Calculated electronic transition band in vacuo.
Calculated oscillator strength in vacuo.
b
c
d
H represents HOMO, L represents LUMO.
4. Experimental
4.1. Materials and measurements
Toluene was freshly distilled from sodium and benzophenone
under nitrogen. CH2Cl2 was distilled from CaH2. All the other
chemicals and reagents were used as received from commercial
sources without further purification. 1H NMR spectra were recor-
ded on a Bruker Avance III 500 MHz and 400 MHz, and Varian
300 MHz using CDCl3 or DMSO-d6 as solvents. 13C NMR spectra
were recorded on Bruker Avance III 125 MHz and 100 MHz using
CDCl3 or DMSO-d6 as solvents. UVevis absorption spectra were
determined on a Shimadzu UV-1601PC spectrophotometer. Fluo-
rescent emission spectra were carried out on a Shimadzu RF-5301
luminescence spectrometer. The quantum yields of the samples
in solid states were measured by an Edinburgh Instrument FLS920
using an integrating sphere with the excitation wavelength of
500 nm. Mass spectra were performed on Agilent 1100 MS series
and AXIMA CFR MALDI/TOF (matrix assisted laser desorption
ionization/time-of-flight) MS (COMPACT). C, H, and N analyses
were taken on a Vario EL cube elemental analyzer. Cyclic voltam-
metry was carried out with a CHI 604B electrochemical working
station at room temperature under N2 atmosphere at a scan rate of
100 mV/s. A three electrode configuration was used for the mea-
surement: a platinum electrode as the working electrode, a plati-
num wire as the counter electrode, and an Ag/AgNO3 electrode as
the reference electrode. Ferrocene was used as external reference. A
solution of Bu4NPF6 (0.1 M) in CH2Cl2 was used as the supporting
electrolyte.
d
8.85 (d, J¼1.5 Hz, 3H), 8.58 (d, J¼1.5 Hz, 3H), 8.18e8.16 (m, 3H),
8.06 (s, 3H), 8.01e7.99 (m, 3H), 7.59 (d, J¼8.5 Hz, 3H), 7.46 (d,
J¼8.5 Hz, 3H), 4.39 (t, J¼7, 7 Hz, 6H), 2.74 (s, 9H), 1.97e1.92 (m, 6H),
1.44e1.24 (m, 54H), 0.86 (t, J¼6.5, 7.5 Hz, 9H) (Fig. S7). 13C NMR
(100 MHz, CDCl3, ppm):
d 197.6, 143.6, 142.9, 140.8, 133.6, 128.9,
126.5, 126.2, 124.9, 123.8, 122.7, 122.1, 119.3, 109.6, 108.5, 53.4, 43.5,
31.9, 29.5, 29.4, 29.3, 29.0, 27.3, 26.6, 22.6, 14.1 (Fig. S8). Elemental
analysis for C84H105N3O3, calcd: (%)C, 83.74; H, 8.78; N, 3.49. Found:
(%) C, 83.63; H, 8.65; N, 3.57. MALDI-TOF MS, m/z (%): calcd for
1205.8 [MþH]þ, found: 1206.0 (100) [MþH]þ (Fig. S9).
4.2.3. 1-(7-Bromo-9,9-dioctyl-9H-fluoren-2-yl)ethanone (5). By fol-
lowing the synthetic procedure for compound 2, compound 5 was
prepared from compound 4 (13.77 g, 29.33 mmol) and acetyl
chloride (3.11 mL, 43.99 mmol) catalyzed by AlCl3 (5.87 g,
43.99 mmol). The crude product was purified by column chroma-
tography (silica gel, petroleum ether/CH2Cl2 v/v¼2/1) to give
a white solid (7.20 g). Yield: 48%. Mp: 70.0e72.0 ꢂC. 1H NMR
(400 MHz, CDCl3, ppm):
d
7.95 (d, J¼8.8 Hz, 2H), 7.72 (d, J¼7.6 Hz,
1H), 7.61 (d, J¼8.0 Hz, 1H), 7.49 (d, J¼6.8 Hz, 2H), 2.66 (s, 3H),
2.05e1.90 (m, 4H), 1.22e1.03 (m, 20H), 0.81 (t, J¼6.8, 7.2 Hz, 6H),
0.58e0.50 (m, 4H) (Fig. S10). 13C NMR (100 MHz, CDCl3, ppm):
d
197.9, 154.1, 150.7, 144.9, 138.8, 136.2, 130.3, 128.3, 126.4, 122.6,
4.2. Synthesis
122.4, 122.0, 119.5, 55.6, 40.0, 31.7, 29.8, 29.1, 26.8, 23.7, 22.6, 14.0
(Fig. S11). Elemental analysis for C31H43BrO. Calcd: (%) C, 72.78; H,
8.47. Found: (%) C, 72.89; H, 8.55. MALDI-TOF MS, m/z (%): calcd for
511.3 [MþH]þ, 513.3 [MþH]þ, found: 511.1 (98) [MþH]þ, 513.1 (100)
[MþH]þ (Fig. S12).
Compounds 1,29 4,30 methyl 4-(diphenylamino)benzoate,31 and
1,3,5-tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzene32
were synthesized according to the literature.
4.2.1. 1-(6-Bromo-9-dodecyl-9H-carbazol-3-yl)ethanone (2). Acetyl
chloride (2.05 mL, 29.0 mmol) was added slowly to a suspension of
AlCl3 (3.88 g, 29.0 mmol) in 1,2-dichloroethane in ice bath over
20 min. Then, the solution of compound 1 (8.0 g, 19.3 mmol) in 1,2-
dichloroethane was added slowly. After that, the ice bath was re-
moved, and the dark green slurry was refluxed overnight. After
4.2.4. 1,10,100-(Benzene-1,3,5-triyltris(9,9-dioctyl-9H-fluorene-7,2-
diyl))triethanone (6). By following the synthetic procedure for
compound 3, compound 6 was prepared from compound 5 (0.88 g,
1.71 mmol) and 1,3,5-tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)benzene (0.20 g, 0.44 mmol) catalyzed by Pd(PPh3)4 (20 mg) in
the presence of K2CO3 (0.60 g, 4.4 mmol). The crude product was

C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
3941
purified by column chromatography (silica gel, petroleum ether/
ethyl acetate, v/v¼10/1) to give a white solid (0.21 g). Yield: 35%.
80.50; H, 7.28; N, 1.81. Found: (%) C, 80.38; H, 7.20; N, 1.98. MALDI-
TOF MS, m/z (%): calcd for 2307.6 (100) [MꢁF]þ, 2326.6 [M]þ, found:
2307.9 (100) [MꢁF]þ, 2326.6 (16) [M]þ (Fig. S21).
Mp: 54.0e56.0 ꢂC. 1H NMR (300 MHz, CDCl3, ppm):
d 8.01e7.99 (m,
6H), 7.91 (d, J¼7.8 Hz, 6H), 7.83e7.77 (m, 6H), 7.72 (s, 3H), 2.69 (s,
9H), 2.09 (t, J¼6.6, 6.9 Hz, 12H), 1.18e1.06 (m, 60H), 0.78 (t, J¼6.6,
7.2 Hz, 18H), 0.73e0.58 (m, 12H) (Fig. S13). 13C NMR (100 MHz,
Acknowledgements
CDCl3, ppm):
d 198.1, 152.9, 151.3, 145.6, 142.8, 141.3, 139.5, 135.9,
This work was supported by the National Natural Science
Foundation of China (_501100001809) (51073068, 21374041),
Open Project of State Key Laboratory of Supramolecular Structure
and Materials (SKLSSM201407), and Open Project of State
Key Laboratory of Theoretical and Computational Chemistry
(K2013-02).
128.3, 126.6, 125.5, 122.5, 121.9, 121.1, 119.6, 55.5, 40.2, 31.7, 29.9,
29.2, 26.8, 23.8, 22.6, 14.0 (Fig. S14). Elemental analysis for
C
99H132O3. Calcd: (%) C, 86.79; H, 9.71. Found: (%) C, 86.80; H, 9.81.
MALDI-TOF MS, m/z (%): calcd for 1371.0 [MþH]þ, found: 1371.5
(100) [MþH]þ (Fig. S15).
4.2.5. 6,60,600-(6,60,600-(Benzene-1,3,5-triyl)tris(9-dodecyl-9H-carba-
zole-6,3-diyl))tris(4-(4-(diphenylamino)phenyl)-2,2-difluoro-2H-
1,3,2-dioxaborinin-1-ium-2-uide) ((TBC)3Ph). Sodium hydride (60%,
0.12 g, 3.00 mmol) was added quickly to a dry flask containing
a solution of compound 3 (0.30 g, 0.25 mmol) and methyl 4-
(diphenylamino)benzoate (0.46 g, 1.51 mmol) in toluene (30 mL).
The reaction mixture was refluxed under an atmosphere of nitro-
gen for 24 h. The solution was cooled to the room temperature and
then acidified with dilute HCl and extracted with CH2Cl2 for three
times. The organic phase was combined and dried over anhydrous
Na2SO4. After removal of solvent, the residue was used directly in
the next step without purification. Then, the solution of 3,30,300-
(6,60,600-(benzene-1,3,5-triyl)tris(9-dodecyl-9H-carbazole-6,3-
diyl))tris(1-(4-(diphenylamino)phenyl)propane-1,3-dione) in dry
CH2Cl2 (30 mL) was heated to reflux under an atmosphere of ni-
trogen, and excess BF3$Et2O (0.5 mL) was added. The mixture was
refluxed for 12 h. After the solvent was removed, the residue was
purified by column chromatography (silica gel, CH2Cl2/petroleum
ether, v/v¼3/1) to afford (TBC)3Ph (100 mg) as a bright red solid.
Yield: 18%. Mp: 198.0e200.0 ꢂC. 1H NMR (500 MHz, DMSO-d6,
Supplementary data
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2014.03.069.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
References and notes
1. Rao, Y. L.; Wang, S. Inorg. Chem. 2011, 50, 12263.
2. Li, D.; Zhang, H. Y.; Wang, Y. Chem. Soc. Rev. 2013, 42, 8416.
3. Loudte, A.; Burgess, K. Chem. Rev. 2007, 107, 4891.
4. Xu, S. P.; Evans, R. E.; Liu, T. D.; Zhang, G. Q.; Demas, J. N.; Trindle, C. O.; Fraser,
C. L. Inorg. Chem. 2013, 52, 3597.
5. Ono, K.; Yoshikawa, K.; Tsuji, Y.; Yamaguchi, H.; Uozumi, R.; Tomura, M.; Taga,
K.; Saito, K. Tetrahedron 2007, 63, 9354.
ꢀ
6. Felouat, A.; D’Aleo, A.; Fages, F. J. Org. Chem. 2013, 78, 4446.
7. Tanaka, K.; Tamashima, K.; Nagai, A.; Okawa, T.; Chujo, Y. Macromolecules 2013,
46, 2969.
ꢀ
8. (a) Cogne-Laage, E.; Allemand, J. F.; Ruel, O.; Baudin, J.; Croquette, V.; Blan-
chard-Desce, M.; Jullien, L. Chem.dEur. J. 2004, 10, 1445; (b) Halik, M.; Wen-
seleers, W.; Grasso, C.; Stellacci, F.; Zojer, E.; Barlow, S.; Bredas, J.; Perry, J. W.;
Marder, S. R. Chem. Commun. 2003, 1490.
ꢀ
60 ꢂC, ppm):
d
9.30 (d, J¼1 Hz, 3H), 8.87 (s, 3H), 8.38e8.36 (m, 3H),
9. (a) Zhang, G. Q.; Lu, J. W.; Sabat, M.; Fraser, C. L. J. Am. Chem. Soc. 2010, 132,
2160; (b) Sun, X. X.; Zhang, X. P.; Li, X. Y.; Liu, S. Y.; Zhang, G. Q. J. Mater. Chem.
2012, 22, 17332; (c) Nguyen, N. D.; Zhang, G. Q.; Lu, J. W.; Sherman, A. E.; Fraser,
C. ,L. J. Mater. Chem. 2011, 21, 8409; (d) Liu, T. D.; Chien, A. D.; Lu, J. W.; Zhang, G.
Q.; Fraser, C. L. J. Mater. Chem. 2011, 21, 8401; (e) Zhang, G. Q.; Singer, J. P.; Kooi,
S. E.; Evans, R. E.; Thomas, E. L.; Fraser, C. L. J. Mater. Chem. 2011, 21, 8295.
10. Poon, C. T.; Lam, W. H.; Wong, H. L.; Yam, V. W. J. Am. Chem. Soc. 2010, 132,
13992.
8.17 (s, 3H), 8.13e8.10 (m, 9H), 7.84e7.81 (m, 6H), 7.65 (s, 3H), 7.36
(t, J¼8.0, 7.5 Hz,12H), 7.21e7.17 (m,18H), 6.82 (d, J¼9.0 Hz, 6H), 4.54
(t, J¼6.5, 6.5 Hz, 6H), 1.90e1.85 (m, 6H), 1.35e1.12 (m, 54H), 0.76 (t,
J¼6.5, 7.5 Hz, 9H) (Fig. S16). 13C NMR (125 MHz, DMSO-d6, 60 ꢂC,
ppm):
d 180.6, 179.1, 153.9, 145.6, 145.1, 142.6, 141.2, 133.9, 131.2,
130.3, 127.2, 126.9, 126.2, 124.8, 123.6, 123.5, 123.1, 122.9, 120.1,
118.4, 110.9, 110.5, 92.6, 43.5, 31.6, 29.4, 29.3, 29.2, 29.0, 28.9, 22.3,
14.1 (Fig. S17). Elemental analysis for C141H141B3F6N6O6. Calcd: (%)
C, 78.33; H, 6.57; N, 3.89. Found: (%) C, 78.56; H, 6.43; N, 3.60.
MALDI-TOF MS, m/z (%): calcd for 2143.1 [MꢁFþH]þ, 2162.1
[MþH]þ, found: 2143.8 (100) [MꢁFþH]þ, 2162.5 (28) [MþH]þ
(Fig. S18).
11. Sun, Y. M.; Rohde, D.; Liu, Y. Q.; Wan, L. J.; Wang, Y.; Wu, W. P.; Di, C. G.; Yu, G.;
Zhu, D. B. J. Mater. Chem. 2006, 16, 4499.
12. (a) Zhang, X. F.; Lu, R.; Jia, J. H.; Liu, X. L.; Xue, P. C.; Xu, D. F.; Zhou, H. P. Chem.
Commun. 2010, 8419; (b) Zhang, X. F.; Liu, X. L.; Lu, R.; Zhang, H. J.; Gong, P. J.
Mater. Chem. 2012, 22, 1167; (c) Liu, X. L.; Xu, D. F.; Lu, R.; Li, B.; Qian, C.; Xue, P.
C.; Zhang, X. F.; Zhou, H. P. Chem.dEur. J. 2011, 17, 1660; (d) Liu, X. L.; Zhang, X.
F.; Lu, R.; Xue, P. C.; Xu, D. F.; Zhou, H. P. J. Mater. Chem. 2011, 21, 8756; (e) Qian,
C.; Cao, K. Y.; Liu, X. L.; Zhang, X. F.; Xu, D. F.; Xue, P. C.; Lu, R. Chin. Sci. Bull. 2012,
57, 4264.
13. (a) Qiu, X. P.; Lu, R.; Zhou, H. P.; Zhang, X. F.; Xu, T. H.; Liu, X. L.; Zhao, Y. Y.
Tetrahedron Lett. 2008, 49, 7446; (b) Qiu, X. P.; Lu, R.; Zhou, H. P.; Zhang, X. F.;
Xu, T. H.; Liu, X. L.; Zhao, Y. Y. Tetrahedron Lett. 2007, 48, 7582.
14. Wang, J. L.; He, Z. C.; Wu, H. B.; Cui, H. B.; Li, Y.; Gong, Q. H.; Cao, Y.; Pei, J. Chem.
dAsian J. 2010, 5, 1455.
15. Zhang, W. B.; Jin, W. H.; Zhou, X. H.; Pei, J. Tetrahedron 2007, 63, 2907.
16. (a) Zhou, H. P.; Zhao, X.; Huang, T. H.; Lu, R.; Zhang, H. Z.; Qi, X. H.; Xue, P. C.;
Liu, X. L.; Zhang, X. F. Org. Biomol. Chem. 2011, 9, 1600; (b) Zhou, H. P.; Lu, R.;
Zhao, X.; Qiu, X. P.; Xue, P. C.; Liu, X. L.; Zhang, X. F. Tetrahedron Lett. 2010, 51,
5287.
17. (a) Jiang, Y. H.; Wang, Y. C.; Hua, J. L.; Tang, J.; Li, B.; Qian, S. X.; Tian, H. Chem.
Commun. 2010, 4689; (b) Wang, B.; Wang, Y. C.; Hua, J. L.; Jiang, Y. H.; Huang, J.
H.; Qian, S. X.; Tian, H. Chem.dEur. J. 2011, 17, 2647.
18. Sun, Y. M.; Xiao, K.; Liu, Y. Q.; Wang, J. L.; Pei, J.; Yu, G.; Zhu, D. B. Adv. Funct.
Mater. 2005, 15, 818.
4.2.6. 6,60,600-(Benzene-1,3,5-triyltris(9,9-dioctyl-9H-fluorene-7,2-
diyl))tris(4-(4-(diphenylamino)phenyl)-2,2-difluoro-2H-1,3,2-
dioxaborinin-1-ium-2-uide) ((TBF)3Ph). By following the synthetic
procedure for the complex (TBC)3Ph, (TBF)3Ph was prepared from
compound 6 (0.40 g, 0.29 mmol), methyl 4-(diphenylamino)ben-
zoate (0.53 g, 1.75 mmol), 60% sodium hydride (0.14 g, 3.50 mmol),
and BF3$Et2O (0.5 mL). The crude product was purified by column
chromatography (silica gel, CH2Cl2/petroleum ether, v/v¼2/1) to
afford (TBF)3Ph (78 mg) as a dark red solid. Yield: 12%. Mp:
158.0e160.0 ꢂC. 1H NMR (500 MHz, CDCl3, ppm):
d 8.13e8.09 (m,
6H), 8.03 (d, J¼9.0 Hz, 6H), 7.93 (t, J¼2.5, 5.0 Hz, 6H), 7.86 (d,
J¼7.0 Hz, 3H), 7.82e7.80 (m, 3H), 7.73 (s, 3H), 7.39 (t, J¼8.0, 8.0 Hz,
12H), 7.26e7.22 (m, 18H), 7.10 (s, 3H), 7.01 (d, J¼9.0 Hz, 6H), 2.12 (t,
J¼6.5, 6.5 Hz, 12H), 1.17e1.06 (m, 60H), 0.77 (t, J¼7.0, 7.0 Hz, 18H),
0.67e0.64 (m, 12H) (Fig. S19). 13C NMR (100 MHz, CDCl3, ppm):
19. Zhao, C.; Wakamiya, A.; Inukai, Y.; Yamaguchi, S. J. Am. Chem. Soc. 2006, 128,
15934.
20. Sonntag, M.; Strohriegl, P. Chem. Mater. 2004, 16, 4736.
21. (a) Yiu, A. T.; Beaujuge, P. M.; Lee, O. P.; Woo, C. H.; Toney, M. F.; Frechet, J. M. J. J.
Am. Chem. Soc. 2012, 134, 2180; (b) Xu, T. H.; Lu, R.; Liu, X. L.; Zheng, X. Q.; Qiu,
X. P.; Zhao, Y. Y. Org. Lett. 2007, 9, 797.
d
180.4, 180.0, 154.2, 153.2, 151.8, 147.2, 145.4, 142.7, 141.8, 139.3,
22. Anderson, J. D.; McDonald, E. M.; Lee, P. A.; Anderson, M. L.; Ritchie, E. L.; Hall,
131.3,131.0,129.9,128.1,126.6,125.9,125.6,122.8,122.7,121.9,121.4,
120.1, 118.5, 92.2, 55.8, 40.3, 31.7, 29.9, 29.2, 29.1, 23.8, 22.5, 14.0
(Fig. S20). Elemental analysis for C156H168B3F6N3O6. Calcd: (%) C,
H. K. J. Am. Chem. Soc. 1998, 120, 9646.
23. Domercq, B.; Grasso, C.; Maldonado, J. L.; Halik, M.; Barlow, S.; Marder, S. R.;
Kippelen, B. J. Phys. Chem. B 2004, 108, 8647.

3942
C. Qian et al. / Tetrahedron 70 (2014) 3935e3942
24. (a) Zhan, Y.; Cao, K. Y.; Xue, P. C.; Lu, R. Tetrahedron Lett. 2013, 54, 594; (b) Jia, J.
H.; Cao, K. Y.; Xue, P. C.; Zhang, Y.; Zhou, H. P.; Lu, R. Tetrahedron 2012, 68, 3626;
(c) Tang, J.; Hua, J. L.; Wu, W. J.; Li, J.; Jin, Z. G.; Long, Y. T.; Tian, H. Energy
Environ. Sci. 2010, 3, 1736.
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J.
V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision A.02; Gaussian: Wallingford, CT,
2009.
26. Zhang, W. W.; Mao, W. L.; Hu, Y. X.; Tian, Z. Q.; Wang, Z. L.; Meng, Q. J. J. Phys.
Chem. A 2009, 113, 9997.
25. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.;
Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Na-
katsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng,
G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery,
T. A.; Peralta, J. E., Jr.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K.
N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.;
Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene,
M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.;
Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
€
27. Lin, Z. H.; Bjorgaard, J.; Yavuz, A. G.; Kose, M. E. J. Phys. Chem. C 2011, 115, 15097.
28. Xue, P. C.; Xu, Q. X.; Gong, P.; Qian, C.; Zhang, Z. Q.; Jia, J. H.; Zhao, X.; Lu, R.; Ren,
A. M.; Zhang, T. R. RSC Adv. 2013, 3, 26403.
29. Pansay, S.; Prachumrak, N.; Jungsuttiwong, S.; Keawin, T.; Sudyoadsuk, T.;
Promarak, V. Tetrahedron Lett. 2012, 53, 4568.
ꢁ
30. Poriel, C.; Rault-Berthelot, J.; Thirion, D.; Barriere, F.; Vignau, L. Chem.dEur. J.
2011, 17, 14031.
31. Gujadhur, R.; Venkataraman, D.; Kintigh, J. T. Tetrahedron Lett. 2001, 42, 4791.
32. Bao, B. Q.; Yuwen, L. H.; Zhan, X. W.; Wang, L. H. J. Polym. Sci., Part A: Polym.
Chem. 2010, 48, 3431.