Synthesis and electrochemical properties of peripheral carbazole functional Ter(9,9-spirobifluorene)s

Article abstract of DOI:10.1021/jo8006094

(Graph Presented) A facile approach for synthesis of spirobifluorene trimers with peripheral carbazole functional groups by utilizing Suzuki coupling as the key reaction has been developed. These novel compounds exhibit blue emission with high quantum yields in solution and thin films, and excellent spectral stability upon photoirradiation and annealing in air. By the introduction of carbazole groups, the oxidation potentials of spirobifluorene trimers STCPC-6 and STCPC-4 were significantly lower than that of model compound STHPH without peripheral carbazole groups, which reflect that the title compounds process higher HOMO energy level and better hole-injection ability. Highly luminescent films were obtained by electrochemical coupling between carbazole units. Pure blue-emission single-layer LEDs based on electrochemical deposition films as light emitting layers were achieved.

Full text of DOI:10.1021/jo8006094

Synthesis and Electrochemical Properties of Peripheral Carbazole
Functional Ter(9,9-spirobifluorene)s
Shi Tang, Meirong Liu, Cheng Gu, Yang Zhao, Ping Lu, Dan Lu, Linlin Liu,
Fangzhong Shen, Bing Yang, and Yuguang Ma*
State Key Laboratory for Supramolecular Structure and Materials, Jilin UniVersity, Changchun, China
ygma@jlu.edu.cn
ReceiVed March 21, 2008
A facile approach for synthesis of spirobifluorene trimers with peripheral carbazole functional groups by
utilizing Suzuki coupling as the key reaction has been developed. These novel compounds exhibit blue
emission with high quantum yields in solution and thin films, and excellent spectral stability upon
photoirradiation and annealing in air. By the introduction of carbazole groups, the oxidation potentials of
spirobifluorene trimers STCPC-6 and STCPC-4 were significantly lower than that of model compound
STHPH without peripheral carbazole groups, which reflect that the title compounds process higher HOMO
energy level and better hole-injection ability. Highly luminescent films were obtained by electrochemical
coupling between carbazole units. Pure blue-emission single-layer LEDs based on electrochemical
deposition films as light emitting layers were achieved.
1. Introduction
green emission after a short-term operation.3 In the literature,
it is attributed to both the excimer/interchain aggregates4 and
the keto defects.5 Recently, more powerful evidence confirmed
that the formation of fluorenone that originated from thermal-
oxidative, photooxidative, or electrooxidative degradation of 9,9-
dialkylated fluorene is mainly responsible for this green emis-
sion.6 To overcome this problem, many previous reports have
concluded that the introduction of bulky phenyl side groups
Fluorene-based polymers and oligomers have been recognized
as very promising classes of organic semiconductors in elec-
tronic devices,1 especially in light-emitting diodes (LEDs),2
because of their high photoluminescence (PL) and electrolu-
minescence (EL) efficiencies. However, the traditional 9,9-
dialkylated fluorene derivatives have shown poor stabilities, with
a drastic loss in quantum yield and the emerging of an undesired
(3) (a) Scherf, U.; List, E. J. W. AdV. Mater. 2002, 14, 477. (b) Marsitzky,
D.; Vestberg, R.; Blainey, P.; Tang, B. T.; Hawker, C. J.; Carter, K. R. J. Am.
Chem. Soc. 2001, 123, 6965. (c) Gaal, M.; List, E. J. W.; Scherf, U.
Macromolecules 2003, 36, 4236. (d) Lupton, J. M.; Craig, M. R.; Meijer, E. W.
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4212 J. Org. Chem. 2008, 73, 4212–4218
10.1021/jo8006094 CCC: $40.75 2008 American Chemical Society
Published on Web 05/10/2008

Carbazole Functional Ter(9,9-spirobifluorene)s
instead of long alkyl chains can effectively suppress the
degradation phenomenon.7 In this context, the spirobifluorene
with unusual rigid three-dimensional structure is an ideal
building block in construction of stable blue-light emitting8 and
plastic laser materials.9 Recently, Bo and co-workers10 reported
a full spirobifluorene polymer and spiro-bridged ladder-type
oligo-p-phenylenes, which exhibited extraordinary thermal and
PL spectral stability. Furthermore, Wong and Wu et al.11
reported the novel optoelectronic material constructed by
spirobifluorene trimer Mod I (the chemical structure is shown
in Scheme 1). This monodisperse trimer exhibited excellent
thermal-stability and high fluorescence quantum yields both in
solution (∼100%) and in solid state (90%). However, the EL
efficiency (1.1 cd A-1) using Mod I is unsatisfactory compared
with its very high solid PL efficiency.11c One of the possibilities
is the unbalanced injection of electrons and holes and their
transport abilities in the film of Mod I. Previous investigations
have demonstrated that the injection of electrons predominates
for fluorene-based polymers and oligomers.12 Thus, the intro-
duction of chromophores with low oxidation potentials, for
example, carbazole,13 into the Mod I is significantly interesting.
Furthermore, in our earlier research, an electrochemically
deposition (ED) operation has been found to prepare the
luminescent film applied for OLEDs.14 In the ED process, the
luminescent precursor can be directly deposited on the
Indium-Tin Oxida (ITO) electrodes through an oxidation
coupling reaction of the electroactive carbazole units.15 Thus,
our goal here is to improve stability of fluorene derivatives and
introduce carbazole units for facile hole injection and transport
while retaining the excellent optoelectronic and thermal proper-
ties of Mod I. For this purpose, a novel series of fluorene trimers
with spirobifluoren backbone and peripheral carbazole functional
groups are synthesized. Additionally, we have also synthesized
their homologous compound without carbazole groups for
comparison in the same condition.
2. Results and Discussion
2.1. Synthesis. The synthetic route of STCPC-6 and STCPC-
4, which contain a spirobifluorene backbone and peripheral
carbazole groups, is depicted in Scheme 1. The synthesis starts
with commercially available 3-bromoanisole (1) to achieve the
key monomers 7 and 8, which can undergo Suzuki coupling
reaction with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)-9,9′-spirofluorene (preparation and purification according to
previous report)11a to afford the title compounds. First, treatment
of 1 with excess amounts of n-butyllithium at -78 °C in THF
and subsequent reaction with trimethyl borate could afford
3-methoxyphenyl boronic acid (2) in 70% yield. 3,3′-Bis-
(methoxy)-biphenyl (3) was obtained with 82% yield by Pd-
catalyzed Suzuki coupling reaction between 1 and 2 in a biphasic
system (toluene/aqueous Na2CO3). Bromination of 2 with
equimolar NBS in DMF at 0 °C gave 2-bromo-5,3′-bis-
(methoxy)-biphenyl (4) in 69% yield. The treated 4 with
n-butyllithium at -78 °C was trapped with 2-bromo-9-fluo-
renone to afford the hydroxy intermediate 9-(5,3′-bis(methoxy)-
biphenyl-2-yl)-2-bromofluorene-9-ol. Then, a successionally
acid-promoted dehydration cyclization reaction in a mixture of
acetic acid and hydrochloric acid to afford 2-bromo-3′,6′-
bis(methoxy)-9,9′-spirofluorene (5) with total yield of 60%. The
geometrical isomer of 5, that is, 2-bromo-1′,6′-bis(methoxy)-
9,9′-spirofluorene, was not obtained by controlling volume ratio
between acetic acid and hydrochloric acid and concentration
of 5 in mixed acid.16 Demethylation of 5 with boron tribromide
in CH2Cl2 at 0 °C gave 2-bromo-9,9′-spirofluorene-3′,6′-diol
(6) in 88% yield. 2-bromo-3′,6′-bis(N-carbazolyl-hexyloxy)-9,9′-
spirofluorene (7) and 2-bromo-3′,6′-bis(N-carbazolyl-butoxy)-
9,9′-spirofluorene (8) have been obtained by reaction of N-(6-
bromohexane)-carbazole or N-(4-bromobutane)-carbazole and
6 in the presence of potassium carbonate in DMF with 70%
and 61% yield, respectively. Finally, Suzuki coupling reactions
between monomers 7 or 8 and 2,7-bis(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)-9,9′-spirobifluorene were performed in a
biphasic system (toluene/aqueous Na2CO3) using Pd(PPh3)4 as
a catalyst precursor, which give the compounds STCPC-6 and
STCPC-4 with different alkoxy length in 80% and 61% yields,
respectively. The model compound STHPH with only alkoxy
substitutions was also afforded from 6 in nearly the same manner
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J. Org. Chem. Vol. 73, No. 11, 2008 4213

Tang et al.
SCHEME 1. Synthesis Route Used to Prepare STCPC-6 and STCPC-4, and Chemical Structure of Mod I
SCHEME 2. Synthesis Route Used to Prepare STHPH
as synthesis of 9 (see Scheme 2). All intermediates and final
products were verified unambiguously by 1H NMR spectroscopy
and mass spectrometry as well as elemental analysis.
2.2. Thermal and Morphologic Properties. We used ther-
mogravimetric analyses (TGA) and differential scanning calo-
rimetry (DSC) to investigate the thermal properties of these
4214 J. Org. Chem. Vol. 73, No. 11, 2008

Carbazole Functional Ter(9,9-spirobifluorene)s
TABLE 1. Summary of Physical Measurements of STCPC-6, STCPC-4, and STHPH
b c
c e
,
f
trimer
λ
a/nm
λ
a b/nm in solution
λ
/nm in films QPLa d/% in solution QPL /% in films Tg /°C Tdg/°C
E
h/V HOMOi/eV
ox
onset
abs
emi
,
emi
,
,
max
max
max
STCPC-6
STCPC-4
STHPH
346
346
350
394
394
394
429
430
423
99
99
99
82
78
65
138
165
108
440
453
401
0.78
0.80
0.98
5.47
5.49
5.67
a Measured in dilute THF. b Excited at 350 nm. c Measured in films (∼100 nm) by spin-coated method. d Measured using quinine sulfate in 1 M
sulfuric acid as standard. e Measured by calibrate integrating sphere system. f Determined by DSC from remelt after cooling with a heating rate of 10
°C/min under N2. g Determined by TGA with a heating rate of 10 °C/min under N2. h Estimated by CV using a glass carbon disk as working electrode,
platinum wire as auxiliary electrode, Ag/Ag+ as reference electrode, [n-NBu4][PF6] as supporting electrolyte in CH2Cl2. i Estimated using the energy
level of the ferrocene (Fc) reference (4.8 eV) and calibrated with E1/2(Fc/Fc+) ) 0.11 V.
FIGURE 3. Absorption and PL spectra of STCPC-6, STCPC-4, and
STHPH in dilute THF solution.
FIGURE 1. DSC scans of STCPC-6, STCPC-4, and STHPH.
FIGURE 4. Absorption and PL spectra of STCPC-6, STCPC-4, and
STHPH in films. (Inset) PL spectra of STCPC-6 film after annealing
at 200 °C in air for 8 h.
FIGURE 2. Powder XRD patterns of STCPC-4.
spirobifluorene trimers. In nitrogen atmosphere, they exhibit
decomposition onset temperatures in the range of 401-453 °C
(see Table 1). As shown in Figure 1, DSC studies indicated
that STCPC-4 and STCPC-6 exhibit only a glass transition at
165 and 138 °C, respectively, whereas STHPH exhibit a glass
transition at 108 °C, followed by crystallization at 190 °C and
melting at 230 °C. Upon cooling from the melts, all of
spirobifluorene trimers have transformed to glass states. The
results reveal that the bulky carbazole units can efficiently hinder
the crystallization process and increase molecular weight. To
further validate morphologic properties in details, the powder
X-ray diffraction analysis of STCPC-4 was determined (see
Figure 2). As can be seen, STCPC-4 shows comparatively broad
and random scattered peaks, demonstrating the noncrystalline
amorphous nature in solid state.
2.3. Optical Properties. Figure 3 and Figure 4 illustrated
the absorption and emission spectra of these spirobifluorene
trimers in dilute THF solution and in films on quartz substrate
by spin-coating, respectively, and the more detailed data was
summarized in Table 1. The absorption bands of STCPC-6
and STCPC-4 appear at 346, 330, and 295 nm in dilute THF
solution and in films. Furthermore, they exhibit very strong
¨
deep blue fluorescence with λmax at 394 nm and shoulder
peaks at 414 and 435 nm as excitation under 350 nm light in
solution, which feature the typical characteristics of the
fluorene trimers.17 Their emission spectra in films show a
slight red shift (λmax at ∼430 nm) compared to that in
solution, however the spectra is still located at deep blue
light region. These compounds exhibit high PL quantum
yields both in the solution (∼100%) and in films (65-82%),
which attributes to reduce the probability of interchain
interactions and prevent close packing of the backbone chains
in tetrahedral steric demand of spirobifluorene structure.
2.4. Annealing and Photodegradation. The spectral stability
of these spirobifluorene trimers were investigated by heat
treatment and photodegradation of films. The inset of Figure 4
showed the PL spectra of STCPC-6 film after annealing at 200
°C in air for 8 h. Although the trimer was annealed at a high
(17) Tang, S.; Liu, M.; Lu, P.; Xia, H.; Li, M.; Xie, Z.; Shen, F.; Gu, C.;
Wang, H.; Yang, B.; Ma, Y. AdV. Funct. Mater. 2007, 17, 2869.
J. Org. Chem. Vol. 73, No. 11, 2008 4215

Tang et al.
FIGURE 5. Normalized emission spectra of a pristine film and the
subsequent photodegradation by a 125 W high-press mercury-arc light
in air for (a) STCPC-6 and (b) THHH.
FIGURE 7. Electropolymerization of STCPC-6 and STCPC-4 during
multiple CV scans. (Inset) Picture of electrochemically deposition film
under UV light (350 nm).
subsequent scans in the potential range, the reduction peak at
0.81 V is observed, which combines with oxidation peak at 1.02
V as reversible p-doping processes of the trimer backbone.
Another reduction peak at 0.45 V is attributed to the formation
of neutral dimeric carbazole from dimeric carbazyl cations.19
The first CV scan of STCPC-4 shows very slight difference
compared with STCPC-6. In contrast, STHPH without carba-
zole groups shows the only oxidation peak of the trimer
backbone at 1.02 V, which is consistent with oxidation peak of
the backbone of STCPC-6. The reduction peak of the trimer
backbone is not observed obviously for STHPH. In view of
our system, the introduction of carbazole groups can enhance
electrochemical stability of materials. The HOMO energy levels
of three compounds estimated from the onset potentials are 5.47
eV for STCPC-6, 5.49 eV for STCPC-4 and 5.67 eV for
STHPH, respectively. These results reveal that the introduction
of carbazole groups can clearly raise HOMO energy level,
thereby improving the hole injection ability in device.
2.6. Electropolymeric and Electroluminescent Properties.
From the second CV scan between -0.6 and 0.8 V as shown
in Figure 7, a new peak appears at oxidation potential (0.65
V), which can be assigned to the oxidation of newly formed
dimeric carbazole in first cycle on the working electrode. As
the electropolymerization proceeds, the oxidation and reduction
currents are increased in successive cycles, indicating the
occurrence of coupling reaction between the carbazole units and
the growth of the film on the working electrode. As shown in
the inset of Figure 7, the electrochemically deposited (ED) films
exhibit strongly blue fluorescence. It is because that the coupling
reaction of pendant carbazole groups occur in relatively low
potentials, which do not effect on luminescent units of ter-
(spirobifluorene)s backbone. The ED film from STCPC-6 also
exhibits very smooth surface morphology with a root-mean-
square (rms) roughness of 2.8 nm (see Figure 8). The EL device
is fabricated by ED method using the most simple device
structure ITO/STCPC-6 (ED film)/Ba (5 nm)/Al (200 nm). The
device exhibits pure blue emission with λmax at 423 nm and
CIE coordinates (0.15, 0.09). The luminance-voltage and
external quantum efficiency-voltage characteristics of the single
layer device were shown in Figure 9. The device using TCPC-6
exhibited a maximum luminance of 401 cd m-2 and a maximum
external quantum efficiency of 0.44% (corresponding to lumi-
nance efficiency of 0.16 cd A-1). Although such EL performance
FIGURE 6. Oxidation part of the CV curves of STCPC-6, STCPC-
4, and STHPH.
temperature, no emission spectral change was found. Figure 5
illustrated the emission spectra of the pristine films and the
subsequent photodegradation under air. The emission spectra
of traditional 9,9-dialkylated fluorene trimer (THHH) was also
showed in the control experiment as compared. For the STCPC-
6, no evident emission spectral change was found in the given
degradation period. In contrast, the low-energy emission bands
around 510 nm of THHH were emerged after degradation and
the intensity was increased with the increase of the degradation
time. Above, the result clearly reveals that the spirobifluorene
structure can effectively restrain the photodegradation resulting
from alkyl oxidation, hence improving the material stability.18
2.5. Electrochemical Properties. The electrochemical prop-
erties of new spirobifluorene trimers are characterized using CV
in a standard three-electrode electrochemical cell in CH2Cl2 at
room temperature. Figure 6 showed CV curves for the first scan.
During anodic scans, STCPC-6 exhibits two oxidation peaks
at 0.90 and 1.02 V. The oxidation peak at the relatively low
potentials of 0.90 V is ascribed to the oxidation of carbazole
units.19 The oxidation species of carbazyl radical cation can react
with each other to form dimeric carbazole, which is the
electropolymeric process on the surface of electrode. The
oxidation of the relatively high potential of 1.02 V is attributed
to oxidation of the backbone of the fluorene trimer.20 In
(18) Liu, L.; Tang, S.; Liu, M.; Xie, Z.; Zhang, W.; Lu, P.; Hanif, M.; Ma,
Y. J. Phys. Chem. B 2006, 110, 13734.
(19) (a) Marrec, P.; Dano, C.; Guentner-Simonet, N.; Simonet, J. Synth. Met.
1997, 89, 171. (b) Inzelt, G. J. Solid State Electrochem. 2003, 7, 503.
(20) (a) Sonntag, M.; Strohriegl, P. Chem. Mater. 2004, 16, 4736. (b)
Kanibolotsky, A. L.; Berridge, R.; Skabara, P. J.; Perepichka, I. F.; Bradley,
D. D. C.; Koeberg, M. J. Am. Chem. Soc. 2004, 126, 13695.
4216 J. Org. Chem. Vol. 73, No. 11, 2008

Carbazole Functional Ter(9,9-spirobifluorene)s
FIGURE 8. AFM image showing 10 µ × 10 µ areas of electrochemically deposition film of STCPC-6.
single-layer LEDs using ED films as a light emission layer
achieve pure blue emission with CIE coordinates (0.15, 0.09)
and maximum external quantum efficiency of 0.44%. Our
findings provide an alternative approach to design luminescent
materials with electropolymerization behaviors for facile LEDs
fabrication.
4. Experimental Section
Compounds 2, 3, and 4 were prepared following a method similar
to that of ref 16, and detailed experimental procedure and
characterization of duplicated compounds 8, 9, STCPC-4, and
STHPH are shown in the Supporting Information.
2-Bromo-3′,6′-bis(methoxy)-9,9′-spirofluorene (5). A solution
of 4 (1.43 g, 4.875 mmol) dissolved in dried THF was cooled to
-78 °C. Then, 3 mL of n-butyllithium (2.5 M/L, 7.5 mmol) was
added slowly. The reaction mixture was stirred for 1 h at -78 °C.
After 1 h, 2-bromo-9-fluorenone (2.14 g, 6.34 mmol) dissolved in
dried THF was added slowly, and the resulting mixture was warmed
to room temperature and stirred for 24 h. Some water poured into
solution and extracted with ether several times. The organic phase
was dried over anhydrous magnesium sulfate. After filtration and
the solvent were removed by rotary evaporation, the crude product
of 9-(5,3′-bis(methoxy)-biphenyl-2-yl)-2-bromofluorene-9-ol was
afforded. This crude product was mixed with acetic acid (150 mL)
and hydrochloric acid (3 mL) and stirred for 36 h at room
temperature. Some water added to the resulting solution and white
solid appeared at once. The precipitate was collected and purified
by column chromatography on silica gel (silica gel, hexane/CH2Cl2)
FIGURE 9. Luminance-voltage and external quantum efficiency-
voltage characteristics in ITO/STCPC-6 (ED film)/Ba/Al device.
is not high, it should be noted that such device based on ED
technique is relatively simple in device fabrication compared
with currently technology such as ink-jet printing for polymer
materials21 and shadow masks for small molecule materials.22
3. Conclusions
In summary, a series of fluorene trimers with spirobifluorene
backbone and peripheral carbazole functional alkoxy-substitution
have been synthesized. These compounds exhibit blue emission
with high quantum yields in the solution and in films, amorphous
morphology with high Tg and excellent color stability. Through
incorporating electroactive carbazole groups as the side chain,
the first oxidation potential is reduced significantly and the
HOMO energy level is heightened, indicating an increased hole
inject ability of the title compounds. Furthermore, STCPC-6
and STCPC-4 are found to have an ability to form highly
luminescent films through electrochemical polymerization, and
then to prepare the LED devices using these ED films. The
1
to afford a white solid (yield 60%). Mp 203-206 °C. H NMR
(500 MHz, CDCl3): δ7.79-7.77 (d, 1H, Ar-H), δ7.68-7.66 (d,
1H, Ar-H), δ7.47-7.45 (d, 1H, Ar-H), δ7.36-7.32 (m, 3H,
Ar-H), δ7.14-7.11 (t, 1H, Ar-H), δ6.85 (s, 1H, Ar-H),
δ6.73-6.72 (d, 1H, Ar-H), δ6.69 (s, 1H, Ar-H), δ6.67 (s, 1H,
Ar-H), δ6.62-6.60 (d, 2H, Ar-H), δ3.89 (s, 6H, OCH3), δ3.83
(s, 3H, CH3). 13C NMR (500 MHz, CDCl3): δ160.4, 151.7, 149.3,
141.1, 140.9, 131.1, 128.6, 128.1, 127.6, 125.1, 124.4, 121.6, 120.4,
114.5, 105.7, 56.0, MS (m/z) 454.2. Anal. Calcd for C27H19BrO2:
C, 71.22; H, 4.21 Found: C, 71.47; H, 4.10.
2-Bromo-9,9′-spirofluorene-3′,6′-diol (6). A solution of boron
tribromide (1 mL) in CH2Cl2 (10 mL) was slowly added to a
solution of 5 in CH2Cl2 (30 mL) at ice-water bath. After the
addition was completed, the ice-water bath was removed and the
reaction mixture was stirred for 24 h at room temperature. The
resulting solution was poured into water (100 mL) and stirred for
1 h, and then extracted with CH2Cl2 several times. The organic
phase was dried over anhydrous magnesium sulfate. After filtration
(21) (a) de Gans, B. J.; Duineveld, P. C.; Schubert, U. S. AdV. Mater. 2004,
16, 203. (b) Burrows, P. E.; Bulovic, V.; Forrest, S. R.; Sapochak, L. S.; McCarty,
D. M.; Thompson, M. E. Appl. Phys. Lett. 1994, 65, 2922. (c) Burrows, P. E.;
Shen, Z.; Bulovic, V.; McCarty, E. M.; Forrest, S. R.; Cronin, J. A.; Thompson,
M. E. J. Appl. Phys. 1996, 10, 79.
(22) (a) Shen, Z.; Burrows, P. E.; Bulovic, V.; Forrest, S. R.; Thompson,
M. E. Science 1997, 276, 2009. (b) Lidzey, D. G.; Pate, M. A.; Weaver, M. S.;
Fisher, T. A.; Bradley, D. D. C. Synth. Met. 1996, 82, 141. (c) Renak, M. L.;
Bazam, G. C.; Roitman, D. AdV. Mater. 1997, 9, 392.
J. Org. Chem. Vol. 73, No. 11, 2008 4217

Tang et al.
and solvent evaporation, the gray solid was recrystallized with
CH2Cl2 to afford white solid (yield 88%). Mp 271-273 °C. H
mmol) were added to the Na2CO3 (2.0 M/L) and toluene (toluene/
water was at a 3:2 ratio), and Pd(PPh3)4 (12 mg) acted as catalyst.
After the reaction mixture was stirred at 90 °C for 48 h under a
nitrogen atmosphere, some water was added to the resulting solution
and then the mixture was extracted with chloroform for several
times. The organic phase was dried over anhydrous magnesium
sulfate. After filtration and solvent evaporation, the liquid was
purified with column chromatography using petroleum ether/CH2Cl2
1
NMR (500 MHz, DMSO-d6): δ9.55 (s, 2H, OH-H), δ7.99-7.97
(d, 1H, Ar-H), δ7.95-7.93 (d, 1H, Ar-H), δ7.56-7.54 (d, 1H,
Ar-H), δ7.39-7.36 (t, 1H, Ar-H), δ7.23 (s, 2H, Ar-H),
δ7.17-7.15 (d, 1H, Ar-H), δ7.67 (s, 1H, Ar-H), δ6.63-6.62 (d,
1H, Ar-H), δ6.55-6.53 (d, 2H, Ar-H), δ6.39-6.37 (d, 2H,
Ar-H). 13C NMR (500 MHz, CDCl3): δ158.5, 152.7, 149.8, 143.6,
141.2, 140.7, 139.1, 131.4, 129.2, 128.7, 126.9, 124.9, 124.4, 123.3,
121.5, 121.3, 116.1, 107.8. MS (m/z) 426.1. Anal. Calcd for
C25H15BrO2: C, 70.27; H, 3.54 Found: C, 70.59; H, 3.76.
1
as the eluent to afford a white solid (yield 80%). H NMR (500
MHz, DMSO-d6): δ8.11-8.09 (d, 4H, Ar-H-car), δ7.90-7.83 (m,
4H, Ar-H-flu), δ7.56-7.54 (m, 6H, Ar-H-flu-car), δ7.39-7.38
(t, 4H, Ar-H-car), δ7.32-7.30 (m, 4H, Ar-H-flu), δ7.13-7.08
(t, 4H, Ar-H-car), δ7.07-7.04 (t, 1H, Ar-H-flu), δ6.98-6.96 (t,
1H, Ar-H-flu), δ6.59-6.50 (m, 6H, Ar-H-flu), δ6.38-6.37 (d,
2H, Ar-H-flu), δ4.38-4.35 (t, 4H, O-CH2), δ3.93-3.91 (t, 4H,
N-CH2), δ1.78-1.76 (m, 4H, CH2), δ1.65-1.63 (m, 4H, CH2),
δ1.42-1.36 (m, 4H, CH2), δ0.85-0.83 (m, 4H, CH2). 13C NMR
(500 MHz, CDCl3): δ159.6, 150.1, 149.9, 149.0, 143.4, 142.2,
141.8, 141.4, 141.3, 141.2, 140.8, 128.2, 128.1, 127.9, 127.5, 127.4,
126.0, 125.1, 124.7, 124.2, 123.3, 122.9, 122.8, 120.8, 120.4, 120.3,
120.2, 119.1, 114.8, 109.0, 106.1, 68.3, 43.3, 30.1, 29.6, 29.3, 27.4,
26.3. MALDI-TOF-MS (M+) 2004.9 (100%). Anal. Calcd for
2-Bromo-3′,6′-bis(N-carbazolyl-hexyloxy)-9,9′-spirofluorene
(7). 6 (400 mg, 0.94 mmol), N-(6-bromohexane)-carbazole (927
mg, 2.82 mmol) and potassium carbonate (649 mg, 4.7 mmol) were
dissolved in DMF. After the reaction mixture was stirred at 150
°C for 48 h, some water was added to the resulting solution, and
then the mixture was extracted with chloroform several times. The
organic phase was dried over anhydrous magnesium sulfate. After
filtration and solvent evaporation, the liquid was purified by column
chromatography on silica gel (silica gel, petroleum ether/CH2Cl2)
to afford white solid (yield 70%). Mp 115-117 °C. 1H NMR (500
MHz, CDCl3): δ8.11-8.10 (d, 4H, Ar-H-car), δ7.78-7.77 (d, 1H,
Ar-H-flu), δ7.67-7.66 (d, 1H, Ar-H-flu), δ7.45-7.56 (m, 9H,
Ar-H-flu-car), δ7.34-7.34 (t, 1H, Ar-H-flu), δ7.22-7.13 (m, 6H,
Ar-H-flu-car), δ7.11-7.10 (t, 1H, Ar-H-flu), δ6.84 (s, 1H, Ar-H-
flu), δ6.72-6.73 (d, 1H, Ar-H-flu), δ6.62-6.59 (d, 2H, Ar-H-
flu), δ6.57-6.56 (d, 2H, Ar-H-flu), δ4.33-4.35 (t, 4H, O-CH2),
δ3.99-3.97 (t, 4H, N-CH2), δ1.95-1.93 (m, 4H, CH2), δ1.79-1.77
(m, 4H, CH2), δ1.54-1.48 (m, 4H, CH2), δ0.87-0.84 (m, 4H,
CH2). 13C NMR (500 MHz, CDCl3): δ159.7, 151.6, 149.9, 143.0,
141.1, 140.3, 131.1, 128.8, 128.2, 127.9, 126.3, 125.1, 124.1, 123.8,
121.8, 120.8, 120.4, 119.3, 115.2, 109.8, 106.0, 68.4, 42.2, 30.8,
29.4, 29.0, 27.9, 26.1. MS (m/z) 924.4. Anal. Calcd for
C61H53N2BrO2: C, 79.12; H, 5.77; N, 3.03 Found: C, 79.13; H,
5.32; N, 3.18.
C147H120N4O4: C, 87.99; H, 6.03; N, 2.79 Found: C, 87.73; H, 5.92;
N, 2.76.
Acknowledgment. We are grateful for financial support from
National Science foundation of China. (grant number 20474024,
90101026, 20573040, 50473001, 50473006, 90501001), and by
Ministry of Science and Technology of China (grant number
2002CB6134003).
Supporting Information Available: General information,
1
LED fabrication and measurement, H NMR, 13C NMR and
MALDI-TOF-MS of new compounds. This material is available
free of charge via the Internet at http://pubs.acs.org.
STCPC-6. 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-
9,9′-spirobifluorene (99.4 mg, 0.175 mmol) and 7 (324.1 mg, 0.35
JO8006094
4218 J. Org. Chem. Vol. 73, No. 11, 2008