Precise synthesis of poly(fluorene-2,7-vinylene)s containing oligo(thiophene)s at the chain ends: Unique emission properties by the end functionalization

Article abstract of DOI:10.1021/ma200638a

Poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs) containing an oligo(thiophene) moiety at the chain ends have been prepared and identified. Fluorescence spectra of PFVs containing 3 or 4 thiophene repeat units at the chain ends showed significant difference in their intensities at ca. 500 and 530 nm from those containing others (2 or 5 thiophene repeat units, etc.). The emission intensities were dependent upon the degree of fluorene-2,7-vinylene repeat unit (PFV conjugation length); the observed differences are thus attributed to an energy transfer from the PFV conjugated main chain to the oligo(thiophene) moieties.

Full text of DOI:10.1021/ma200638a

ARTICLE
pubs.acs.org/Macromolecules
Precise Synthesis of Poly(fluorene-2,7-vinylene)s Containing
Oligo(thiophene)s at the Chain Ends: Unique Emission
Properties by the End Functionalization
Shingo Kuwabara,† Nobuhiro Yamamoto,† Prabhuodeyara M. Veeresha Sharma,† Kenji Takamizu,‡
Michiya Fujiki,† Yves Geerts,§ and Kotohiro Nomura*,†,‡
†Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0101, Japan
‡Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami Osawa, Hachioji, Tokyo 192-0397, Japan
§Laboratoire de Chimie des Polymꢀeres, Facultꢁe des Sciences, Universitꢁe Libre de Bruxelles (ULB), 1050 Bruxelles, Belgium
S Supporting Information
b
ABSTRACT: Poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs)
containing an oligo(thiophene) moiety at the chain ends have
been prepared and identified. Fluorescence spectra of PFVs
containing 3 or 4 thiophene repeat units at the chain ends
showed significant difference in their intensities at ca. 500 and
530 nm from those containing others (2 or 5 thiophene repeat
units, etc.). The emission intensities were dependent upon the
degree of fluorene-2,7-vinylene repeat unit (PFV conjugation
length); the observed differences are thus attributed to an
energy transfer from the PFV conjugated main chain to the
oligo(thiophene) moieties.
’ INTRODUCTION
attempts for synthesis of PPVs by this approach afforded oligomer
mixtures.13,14
Organic electronics are one of the most important emerging
technologies, and conjugated polymers, such as poly(p-aryleneviny-
lene)s and poly(thiophene)s, are promising semiconducting
materials.1ꢀ6 A subject concerning synthesis of structurally regular,
chemically pure polymers by the development of new synthetic
methods attracts considerable attention1ꢀ3 because their device
performances are generally affected by polymer structural regularity,
chemical purity, and supramolecular order.4ꢀ6 Fluorene-based
electroluminescent (EL) polymers are known to be promising in
terms of a facile introduction of substituents into the C9 position,
high photoluminescence (PL) and EL efficiencies, and thermal and
chemical stabilities.7ꢀ10 Synthesis of structurally regular, chemically
pure polymers by development of new synthetic methods attracts
considerable attention1 because their device performances are
affected by polymer structural regularity, chemical purity, and
supramolecular order.2ꢀ4
We reported that stereoregular (all-trans), high molecular
weight poly(9,9-dialkylfluorene-2,7-vinylene)s (PFVs) could be
prepared by acyclic diene metathesis (ADMET) polymerization
of 9,9-dialkyl-2,7-divinylfluorene using Mo(N-2,6-Me2C6H3)-
(CHCMe2Ph)[OCMe(CF3)2]2 (Mo)7 or RuCl2(PCy3)(IMes-
H2)(CHPh) [Ru, Cy = cyclohexyl, IMesH2 = 1,3-bis(2,4,6-trimethyl-
phenyl)imidazolin-2-ylidene]8,9 under optimized conditions.11 The
conditions for synthesis of PFVs8 were also effective for syntheses of
high molecular weight poly(2,5-dialkylphenylene-1,4-vinylene)s
(PPVs).12 The facts introduced interesting contrast because the initial
Although the strict control of the repeating units cannot be
attained in the present ADMET condensation polymerization (Mw/
Mn = ca. 2), the resultant polymers possessed the following
promising characteristics: (1) defect free without termination of
conjugated units, any negative impurities (halogen, sulfur, etc.) and
(2) highly trans olefinic double bonds (because the reaction
proceeds via metallacycle intermediate13,14). Moreover, the resul-
tant polymers prepared by Ru possessed well-defined polymer chain
ends (as vinyl group),8,9 and we thus demonstrated more recently
that a facile, exclusive end functionalization can be achieved by
treating the vinyl groups in PFV with Mo followed by Wittig-type
cleavage with 4-Me3SiOC6H4CHO; precise synthesis of ABA type
amphiphilic triblock copolymers had thus been accomplished by
grafting PEG into both the PFV chain ends (Scheme 1).8
On the basis of the above results, we thus focus on the
synthesis of various PFVs containing functionalities at the both
polymer chain ends by adopting this approach. It should be
stressed that successful examples of precise synthesis of telechelic
conjugated polymers (containing functional group at the both
chain ends) have been limited,15,16 although they paved the way
to the formation of regular one-dimensional conjugated structures
Received: March 20, 2011
Revised:
April 9, 2011
Published: April 21, 2011
r
2011 American Chemical Society
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Scheme 1. Precise Synthesis of Amphiphilic Triblock Copolymers Consisting of Poly(ethylene glycol) (PEG) and Poly(fluorene-
2,7-vinylene) (PFV) Prepared by Acyclic Diene Metathesis (ADMET) Polymerization8
Scheme 2
on the nanoscale from the assembling properties of rodꢀcoil
block copolymers. Through this approach, we herein present
the synthesis of PFV’S containing oligo(thiophene)s in the
both chain ends by adopting the approach, as a demonstration
of functionalization of a conjugated polymer at the end groups
by π-systems (Scheme 2). We also wish to present that the
emission property in the resultant conjugated polymers can be
modified by introduction of oligo(thiophene) moieties at the
chain ends.17,18
’ RESULTS AND DISCUSSION
Synthesis of End-Functionalized PFVs. Acyclic diene me-
tathesis (ADMET) polymerization of 2,7-divinyl-9,9-di-n-
octylfluorene8,9 was conducted in the presence of Ru catalyst
according to the established conditions under a reduced pressure
(reaction time 3 h). The resultant poly(9,9-di-n-octylfluorene-2,7-
vinylene) (PFV) possessed high molecular weight with unimodal
molecular weight distribution (by GPC analysis: Mn = 2.60 ꢁ 104,
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Mw/Mn = 1.96).19 Removal of ethylene byproduced from the
reaction medium is a prerequisite for obtainment of the high
molecular weight polymers in this catalysis,7ꢀ9 and rather low
molecular weight PFV was obtained when the reaction was
terminated at short period (1 h, by GPC analysis: Mn = 1.67 ꢁ
104, Mw/Mn = 2.19). As demonstrated previously,8,9 the resultant
PFVs possessed exclusive trans regularity as well as vinyl groups at
the both polymer chain ends as confirmed by 1H NMR spectra.
According to our reported procedures,8 the vinyl groups at the
PFV chain ends were treated with Mo (2.5 equiv to the vinyl
group, to generate Moꢀalkylidene moieties) and the subsequent
addition of excess amount (ca. 2 equiv to Mo) of various
aldehydes (ArCHO) gave PFVs containing functionalities at
the both polymer chain ends (PFV-Ar2, Scheme 2). The results
are summarized in Table 1, and the 1H NMR spectra are shown
in the Supporting Information.20 Slight increases in the Mn values
in the resultant polymers after treatment with ArCHO were
observed by GPC measurement in most cases, and the results
were reproducible (runs 4 and 5): protons corresponding to the
shown in Scheme 2, precise, exclusive syntheses of PFVs (PFV-
Ar2) containing substituted thiophenes or (oligo)thiophene
moieties at both polymer chain ends have been achieved by
adopting the present approach.
UVꢀvis and Fluorescence Spectra for PFV-Ar2. Figure 1
shows (a) UVꢀvis spectra and (b) fluorescence spectra
(excitation wavelength at 460 nm) for various PFVs containing
(oligo)thiophene moiety at the polymer chain ends (PFV and
PFV-Ar2, 1.0 ꢁ 10ꢀ6 M in THF at 25 °C). As reported
previously,7,9 the UVꢀvis spectrum for PFV (before mod-
ification) displays two absorption bands at 427 and 455 nm,
which can be attributed to πꢀπ* transitions of the conjugated
backbone, which can be attributed to πꢀπ* transitions of the
conjugated backbone.10e No significant changes were observed
in the spectra for PFVs after introduction of functionalities (Ar
group, Figure 1a); the spectra for PFV-TP and PFV-TN were
also analogous to that for PFV-2T.20
Figure 1b shows fluorescence spectra (in THF, 1.0 ꢁ 10ꢀ6 M
at 25 °C, excitation wavelength at 460 nm) for various PFVs
containing (oligo)thiophene moiety at the polymer chain ends
(shown in Scheme 2). The spectra in most PFVs with excitation
at 460 nm showed a strong emission band at ca. 465 nm with a
shoulder at 496 nm along with a slight shoulder at 530 nm
(Figure 1b). It is already explained that the shoulder arises from
coupling between the fluorene and vinylene units to form a new
electronic state with a lower energy.22
1
chain ends could be observed in the H NMR spectra.20 As
1
reported previously,8,9 the Mn value estimated by H NMR
spectrum (by integration ratio, run 6, Mn(NMR) = 11 400) was
close to the exact value estimated from the Mn value by GPC
(Mn(calc) = 11 800).21 The fact thus strongly suggests that, as
Note that the spectra for PFVs containing three or four thiophene
repeat units (PFV-3T, PFV-MP3T, PFV-DH4T) were apparently
different from those for PFV and the others (PFV-2T, PFV-6T). In
particular, the intensities at ca. 497ꢀ500 and 528ꢀ531 nm for
these polymers (PFV-3T, PFV-MP3T, PFV-DH4T) were high-
er than those for the others (PFV, PFV-2T, PFV-6T). The
spectra for PFV-TN, PFV-TP were also close to that for PFV-
2T.20 It thus seems likely that a certain number of thiophene
repeat units (3ꢀ4) would be important for the unique observa-
tion in the fluorescence spectra.
In order to clarify this observation in the fluorescence spectra
(by PFV-3T, PFV-MP3T, PFV-DH4T), the spectra for PFV-3T
were measured in various solvents (THF, chloroform, toluene at
25 °C, Figure 2a) at various temperatures (in THF at ꢀ5 to
50 °C, Figure 2b). This is because that one appropriate assump-
tion for explaining the observed fact may be due to an aggrega-
tion of the oligo(thiophene) moieties at the polymer chain ends.
However, importantly, no significant changes in the spectra were
observed even if the spectra were measured in various solvents at
various temperatures; no apparent differences in the spectra were
observed for other PFVs (PFV, PFV-2T, PFV-6T) measured at
Table 1. Precise Synthesis of End-Functionalized Poly(9,9-
di-n-octylfluorene-2,7-vinylene)s (PFV-Ar2)a
PFV
PFV-Ar2
run Mn ꢁ 10ꢀ4 Mw/Mn
ArCHOc Mn ꢁ 10ꢀ4 Mw/Mn yieldd/%
b
b
b
b
1
2
3
4
5e
6
7
8
9
2.60
2.60
2.60
2.60
2.60
1.67
2.60
2.60
2.60
1.96 TN-CHO
1.96 TP-CHO
1.96 2T-CHO
1.96 3T-CHO
1.96 3T-CHO
2.19 3TCHO
1.96 MP3T-CHO
1.96 DH4T-CHO
1.96 6T-CHO
2.71
2.64
2.68
2.77
2.64
1.72f
2.81
2.60
2.75
1.96
1.98
1.95
1.93
2.02
2.12
1.93
2.01
1.92
98
98
96
>99
>99
93
93
>99
>99
a Detailed conditions are shown in Scheme 2 and the Experimental
Section. b GPC data in THF vs polystyrene standards. c ArCHO shown
e
in Scheme 2. d Isolated yields. Independent runs for reproducibility.
f Mn = 1.18 ꢁ 104 (estimated by GPC data: Mn(GPC)/1.6 þ 3T) vs Mn =
1.14 ꢁ 104 (by 1H NMR based on integral ratio).
Figure 1. UVꢀvis spectra (left, concentration 1.0 ꢁ 10ꢀ6 M in THF at 25 °C) and the fluorescent spectra (right, concentration 1.0 ꢁ 10ꢀ6 M in THF at
25 °C, excitation at 460 nm) for poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs) containing various end groups.
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Figure 2. Fluorescent spectra in (a) various solvents (concentration 1.0 ꢁ 10ꢀ6 M at 25 °C) and (b) at various temperatures (concentration 1.0 ꢁ 10ꢀ6
M in THF), excitation at 460 nm) for PFV-3T [poly(9,9-di-n-octylfluorene-2,7-vinylene) containing three thiophene repeat units at both ends].
Table 2. Fluorescence Lifetimes of Thiophene-Functiona-
lized PFVs (λem = 530ꢀ609 nm)a
PFV-Ar
τ/ns
PFV-Ar
τ/ns
PFV
0.521
0.534
0.654
PFV-MP3T
PFV-DH4T
0.746
0.697
PFV-2T
PFV-3T
a Measured in THF with a concentration of 1.0 ꢁ 10ꢀ6 M with
395ꢀ405 nm excitation in range of 5 ns at 25 °C. Detailed results are
shown in the Supporting Information.20
been widely investigated for photoelectron transfer studies as well as
for nonlinear optics.18,24 In contrast, precise and total end functio-
nalization of conjugated polymers has never been successful so
far.15,16 As far as we know, this is the first example not only for the
precise synthesis of end-functionalized conjugated polymers but also
for demonstration that the emission properties in the conjugated
polymers can be modified by introduction of functionality at the
chain ends. We are currently expanding the chemistry including
other possibilities by the end functionalization.
Figure 3. Fluorescent spectra of PFV-3T [poly(9,9-di-n-octylfluorene-
2,7-vinylene) containing three thiophene repeat units at both ends]
(concentration 1.0 ꢁ 10ꢀ6 M in THF, excitation at 460 nm) with
different PFV repeating units (Mn = 27 700 vs 17 200).
various temperatures (in THF at ꢀ5 to 50 °C).20 Note, in
contrast, the intensities at ca. 500 and 530 nm in PFV-3T were
affected by the Mn value of the original PFV (Figure 3, degree of
repeating units of the fluorene-2,7-vinylene, conjugation length).
Moreover, the spectra were not dependent upon the excitation
wavelength.20
’ EXPERIMENTAL SECTION
General Procedure. All experiments were carried out under a
nitrogen atmosphere in a Vacuum Atmospheres drybox or using
standard Schlenk techniques. All chemicals used were of reagent grades
and were purified by the standard purification procedures. Anhydrous
grade toluene (Kanto Kagaku Chemical Co., Inc.) was transferred into a
bottle containing molecular sieves (mixture of 3A 1/16, 4A 1/8, and 13X
1/16) in the drybox, stored over sodium/potassium alloy in the drybox,
and then passed through an alumina short column prior to use.
Anhydrous grade dichloromethane, tetrahydrofuran (THF), DMF
(Kanto Kagaku Chemical Co., Inc.), and 1,2-dimethoxyethane
(Aldrich Chemical Co.) were also transferred into a bottle containing
molecular sieves (mixture of 3A 1/16, 4A 1/8, and 13X 1/16) in the
drybox. Mo(N-2,6-Me2C6H3)(CHCMe2Ph)[OCMe(CF3)2] (Mo)25
was prepared according to the literature, and RuCl2(PCy3)(IMesH2)-
(CHPh) [Ru, Cy = cyclohexyl, IMesH2 = 1,3-bis(2,4,6-trimethylphe-
nyl)imidazolin-2-ylidene] (Strem Chemicals, Inc.) was used in the
drybox as received without further purification. Polymerization grade
of 2,7-divinyl-9,9-di-n-octylfluorene was prepared according to the
previous report.8,9,12 Thianaphthene-3-carboxaldehyde (TN-CHO),
6-(2-thienyl)-2-pyridinecarboxaldehyde (TP-CHO), 2,20-bithiophene-
5-carboxaldehyde (2T-CHO), and 2,20:50,200-terthiophene-5-
carboxaldehyde (3T-CHO) were used in the drybox as received
Taking into account the above facts, the unique fluorescence
spectra observed by PFV-3T, PFV-MP3T, and PFV-DH4T are
assumed to be ascribed as due to an energy transfer from the PFV
conjugated main chain to the oligo(thiophene) moieties [not
due to aggregation of rather planar oligo(thiophene)
moieties];15,16 three or four repeating units seems to be favored
than two (PFV-2T) or longer repeating units (PFV-6T).23
Table 2 summarizes fluorescence life times estimated on the
basis of fitting curves for fluorescence decays measured in THF
(at 25 °C).20 It should also be noted that the fluorescence life
times (λem = 530ꢀ609 nm in THF) in PFV-3T, PFV-MP3T,
and PFV-DH4T (τ = 0.654, 0.746, and 0.697 ns, respectively) are
longer than those in the others (PFV, PFV-2T: 0.521, 0.534 ns,
respectively).20
We have shown that various end-functionalized PFVs have been
prepared and identified and that the PFVs containing 3 or 4
thiophene repeat units at the chain ends showed remarkable
differences in the intensities at ca. 500 and 530 nm from the other
samples due to an energy transfer from the PFV to the oligo-
(thiophene). The control of end groups in conjugated oligomers,
especially a donor on one side and an acceptor on another side, has
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(Aldrich Chemical Co.) without further purification. 500-Bromo-2,20:50,200-
terthiophene-5-carboxaldehyde, 2,4,6-trimethoxtphenylboronic acid
neopentyl glycol ester, 3,3000-dihexyl-2,20:50,200:500,2000-quaterthiophene,
R-sexithiophene, and phosphorus oxychloride were also used in the
drybox as received (Aldrich Chemical Co.) without further purification.
All 1H and 13C NMR spectra were recorded on a JEOL JNM-LA400
spectrometer (399.65 MHz, 1H; 100.40 MHz, 13C), and all chemical shifts
are given in ppm and are referenced to SiMe4. Obvious multiplicities and
routine coupling constants are usually not listed, and all spectra were
obtained in the solvent indicated at 25 °C unless otherwise noted. Molecular
weights and the molecular weight distributions of the resultant polymers
were measured by gel-permeation chromatography (GPC). HPLC grade
THF was used for GPC and was degassed prior to use. GPC were
performed at 40 °C on a Shimadzu SCL-10A using a RID-10A detector
(Shimadzu Co. Ltd.) in THF (containing 0.03 wt % of 2,6-di-tert-butyl-p-
cresol, flow rate 1.0 mL/min). GPC columns (ShimPAC GPC-806, 804,
and 802, 30 cm ꢁ 8.0 mm diameter, spherical porous gel made of styrene/
divinylbenzene copolymer, ranging from <102 to 2 ꢁ 107 MW) were
calibrated versus polystyrene standard samples. UVꢀvis spectra for the
resultant polymers were measured by using a Jasco V-550 UV/vis spectro-
photometer (ex. 1.0 ꢁ 10ꢀ6 M in THF at 25 °C), and the fluorescence
spectra were measured by an Hitachi F-4500 fluorescence spectrophoto-
meter (ex. 1.0 ꢁ 10ꢀ6 M in THF at 25 °C) with excitation wavelength at
460, 430, and 410 nm. Measurements of fluorescence lifetime (1.0 ꢁ 10ꢀ6
M in THF at 25 °C) were conducted by using a Picosecond fluorescence
measurement system (Hamamatsu Photonics K. K.) with Spectra Pro 2300i
imaging spectrographs and monochromators (Nippon Roper K. K.).
Polymerization Procedure: Synthesis of Poly(9,9-di-n-
octylfluorene-2,7-viynlene) (PFV) by RuCl2(PCy3)(IMesH2)-
(CHPh). The polymerization procedure employed (Table 1) was analogous
to those reported previously.8,9 Toluene (1.0 mL), 2,7-divinyl-9,9-di-n-
octylfluorene (80 mg, 180.7 μmol), and RuCl2(PCy3)(IMesH2)(CHPh)
[Ru, 4.6 μmol] were charged into a sealed Schlenk-type tube equipped with
Kontes high-vacuum valves in the drybox. The tube was then placed into a
liquid nitrogen bath and was then connected to the vacuum line for a while.8,9
The tube was then placed into an oil bath preheated at the prescribed
temperature under a reduced pressure, and the mixture was stirred for 3 h.
During the reaction, the mixture was placed into a liquid nitrogen bath with a
certain period [every 10 min at the initial 1 h, then every 30 min for 1 h, and
then every 1 h] to remove ethylene from the reaction medium by opening the
valve connected to the vacuum line and then placed into the oil bath to
continue the reaction. The polymerization was quenched by adding ethyl
vinyl ether in excess amount. The reaction mixture was then stirred for 1 h for
completion. The resultant solution was poured into cold methanol (ca.
50 mL) and precipitated for 10 min at 5000 rpm. The yellow polymer was
collected with 0.45 μm membrane filter and was then dried in vacuo. Yield
>99%. Samples for the end functionalized (Mn = 26000, Mw/Mn = 1.96)
were prepared by repeated experimental runs; the low molecular weight
polymer sample (Mn = 16700, Mw/Mn = 2.19) was prepared by terminating
the reaction after 1 h. 1H NMR (C2D2Cl4, tetrachloroethane-d4, at 25 °C): δ
7.67 (br, 2H), 7.51 (br s, 4H), 7.26 (br s, 2H, trans-CHdCHꢀ), 2.00 (br),
1.8 (br), 1.23 (br s), 1.09 (br s), 0.85 (br s). In addition, resonances at δ 6.82
2.0 mmol), and 2,4,6-trimethoxtphenylboronic acid neopentyl glycol
ester (140 mg, 528 mmol) were added. The reaction mixture was then
heated to reflux for 15 h. The mixture was extracted by CH2Cl2 (3 ꢁ
30 mL), and the organic layer was collected and evaporated in vacuo. The
residue was subjected to a column chromatography (silica gel, n-hexane:
ethyl acetate = 8:2 as eluent) to give the target compound (MP3T-
CHO) as orange solids. Yield 49 mg (22%). 1H NMR (CDCl3): δ 9.85
(s, 1H), 7.67 (d, 1H, J = 3.6 Hz), 7.35 (d, 1H, J = 3.6 Hz), 7.28 (d, 1H, J =
4.0 Hz), 7.23 (d, 1H, J = 4.0 Hz), 7.20 (d, 1H, J = 4.0 Hz), 7.12 (d, 1H, J =
3.6 Hz,), 6.23 (s, 2H), 3.87 (s, 9H). 13C NMR (CDCl3): δ 182.5, 160.9,
158.7, 147.4, 141.4, 140.3, 137.6, 135.3, 135.2, 133.8, 129.2, 127.2, 124.0,
123.9, 123.9, 105.1, 91.2, 56.1, 55.6. MS (MALDI, matrix: dithranol):
calcd: 442.04; found: 442.05.
Synthesis of 3,3000-Dihexyl-2,20:50,200:500,2000-quaterthio-
phene-5-carboxaldehyde (DH4T-CHO)27. DMF (111.9 mg,
1.53 mmol) was added into a solution of 3,3000-dihexyl-2,20:50,200:500,2000-
quaterthiophene (700 mg, 1.40 mmol) in 1,2-dichloroethane (7.0 mL).
Phosphorus oxychloride (234.6 mg, 1.53 mmol) was added slowly at
0 °C, and the mixture was then stirred at 40 °C for 12 h. The reaction
mixture was extracted by CHCl3, and the extract was washed with water
and dried over MgSO4. After removal of solvent in vacuo, the residue was
purified by column chromatography (silica gel, hexane:CHCl3 = 1:1 as
eluent) and was then recrystallized from hexaneꢀCHCl3 to give orange
solids of DH4T-CHO. Yield 251 mg (34%). 1H NMR (CDCl3): δ 9.83
(s, 1H), 7.56 (s, 1H), 7.12ꢀ7.18 (m, 4H), 7.03 (d, 1H, J = 3.6 Hz,), 6.94
(d, 1H, J = 5.2 Hz,), 2.76ꢀ2.82 (m, 4H), 1.62ꢀ1.72 (m, 4H), 1.32ꢀ1.42
(m, 12H), 0.89ꢀ0.94 (m, 6H). 13C NMR (CDCl3): δ 182.4, 140.9,
140.3, 140.2, 140.0, 139.1, 139.0, 136.3, 135.9, 133.7, 130.2, 130.1, 128.2,
126.5, 124.6, 124.1, 124.0, 31.7, 31.7, 30.6, 30.2, 29.5, 29.4, 29.3, 29.2,
22.7, 22.7, 14.2, 14.2.
Synthesis of r-Sexithiophene-5-carboxaldehyde (6T-
CHO)26. Phosphorus oxychloride (64 mg, 420 μmol) was slowly added
into a 1,2-dichloroethane solution (509 mg) containing DMF (38 mg,
517 μmol). The mixture was stirred at 25 °C for 1 h. A 1,2-dichlor-
oethane solution (509 mg) containing R-sexithiophene (200 mg, 404
μmol) was then added slowly into the mixture, and the solution was
stirred at 25 °C for 1 h and was then stirred for an additional 12 h at
80 °C. The reaction mixture was poured into water (50 mL) and stirred
for 2 h. Filtrated residue was dissolved in THF and precipitated in
hexane to give dark red powder of 6T-CHO. Yield 118 mg (56%). In
addition, it was found that resultant solid was a mixture of 6T-CHO and
starting material R-sexithiophene by following analyses. But the mixture
was used without further purification, because 6T-CHO and R-sexi-
1
thiophene have poor solubility. H NMR (C2D2Cl4): δ 9.85 (s, 1H),
8.32 (s, 2H), 7.72 (m, 1H), 7.10ꢀ7.35 (m, 5H). 1H NMR (CDCl3): δ
9.88 (s), 8.30 (s), 7.69 (s), 7.15ꢀ7.40 (m). 13C NMR (CDCl3): δ
184.77, 124.03, 123.42, 117.30, 116.75, 116.44, 116.14. IR (KBr, cmꢀ1):
3062 (νCdCꢀH), 1665 (CdO), 1442, 1219, 1069, 793, 457
(thiophene rings). MS (MALDI, matrix: 2,5-dihydroxybenzoic acid):
calcd: 521.94; found: 522.10.
End Functionalization of PFV by Mo(N-2,6-Me2C6H3)-
(CHCMe2Ph)[OCMe(CF3)2]8. The experimental procedure was ana-
logous to that reported previously.8 Into a stirred toluene solution
(2.5 mL) containing poly(2,7-divinyl-9,9-di-n-octylfluorene) (PFV, 50
mg), a toluene solution (0.5 mL) containing Mo(N-2,6-Me2C6H3)-
(CHCMe2Ph)[OCMe(CF3)2]2 [Mo, 3.6ꢀ4.7 equiv] was added at
room temperature, and the solution was stirred for 2 h. The solution
was then added prescribed aldehyde (ArꢀCHO) in excess amount
(>5.43 equiv to Mo) and was stirred for an additional 1 h for completion.
The solution was then poured dropwise into methanol, and the
precipitated samples were collected by centrifuge for 10 min at
5000 rpm. The yellow polymer, PFV-Ar, was collected on a 0.45 μm
membrane filter and was then dried in vacuo. PFVs for this reaction were
dissolved in toluene in the drybox, the solution was passed through a
1
(dd), 5.82 (d), and 5.27 (d) ppm were observed. H NMR (CDCl3 at
25 °C): δ 7.67 (d, 2H, J = 7.2 Hz), 7.72 (br,4H), 7.27 (br, 2H, trans-
CHdCHꢀ), 6.82 (dd), 5.82 (d), 5.27 (d),2.03 (br, 4H), 1.18ꢀ1.07 (br,
20H), 0.79 (t, 6H, J = 6.4 Hz, CH3), 0.66 (br, 4H). 13C NMR (CD2Cl4 at
25 °C): δ 151.8, 140.8, 136.4, 125.9, 120.9, 120.2, 55.1, 40.5, 32.1, 31.8, 30.3,
29.5, 24.0, 22.9, 14.4. 13C NMR (CDCl3 at 25 °C): δ 14.1, 15.7, 22.6, 23.8,
29.3, 30.1, 31.8, 40.8, 55.1, 120.0, 120.6, 125.8, 128.6, 136.5, 140.6, 151.6.
Synthesis of 500-(2,4,6-Trimethoxyphenyl)-2,20:50,200-ter-
thiophene-5-carboxaldehyde (MP3T-CHO)26. Into a 1,2-di-
methoxyethane (25 mL) solution containing Pd(PPh3)4 (80 mg, 70
μmol) under a nitrogen atmosphere, 500-bromo-2,20:50,200-terthiophene-
5-carboxaldehyde (178 mg, 500 mmol), aqueous K2CO3 (1.0 mL, 2M,
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Celite pad, and the filtrate was dried in vacuo; the process is required to
remove oxygen and water contaminant in the polymer samples (because
the molybdenum catalyst is highly sensitive to the impurities).
PFV-TP. Yield: 98%. 1H NMR (CDCl3) δ: [7.00ꢀ8.00, thienyl-
pyridine], 7.68 (d, 2H, J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04
(br, 4H), 1.15 (m, 20H), 0.79 (t, 6H, J = 7.0 Hz), 0.66 (br, 4H).
Polymers, 3rd ed.; Skotheim, T. A., Reynolds, J., Eds.; CRC Press: Boca
Raton, FL, 2007.
(2) (a) Grimsdale, A. C.; M€ullen, K. In Macromolecular Engineering;
Matyjaszewski, K., Gnanou, Y., Leibler, L., Eds.; Wiley-VCH: Weinheim,
Germany, 2007; Vol. 4, pp 2225ꢀ2262. (b) Bielawski, C. W.; Wilson,
C. G. In Macromolecular Engineering; Matyjaszewski, K., Gnanou, Y.,
Leibler, L., Eds.; Wiley-VCH: Weinheim, Germany, 2007; Vol. 4, pp
2263ꢀ2293. (c) Laclerc, N.; Heiser, T.; Brochon, C.; Hadziioannou, G.
In Macromolecular Engineering; Matyjaszewski, K., Gnanou, Y., Leibler,
L., Eds.; Wiley-VCH: Weinheim, Germany, 2007; Vol. 4, pp
2369ꢀ2408.
1
PFV-TN. Yield: 98.0%. H NMR (CDCl3) δ: [7.00ꢀ8.00, thianaph-
thene], 7.68 (d, 2H, J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04 (br, 4H),
1.15 (m, 20H), 0.79 (t, 6H, J = 7.0 Hz), 0.66 (br, 4H).
PFV-2T. Yield: 96%. 1H NMR (CDCl3) δ: [7.00ꢀ7.50,
bithiophene], 7.68 (d, 2H, J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H),
2.04 (br, 4H), 1.15 (m, 20H), 0.79 (t, 6H, J = 7.0 Hz), 0.66 (br, 4H).
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1
PFV-3T. Yield: >99%. H NMR (CDCl3) δ: [6.20ꢀ7.20, terthio-
phene], 7.68 (d, 2H, J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04 (br,
4H), 1.15 (m, 20H), 0.79 (t, 6H, J = 7.0 Hz), 0.66 (br, 4H).
1
PFV-MP3T. Yield: >99%. H NMR (CDCl3) δ: [6.90ꢀ7.50, 6.24
(bs), 3.86 (bs), trimethoxyphenylterthiophene], 7.68 (d, 2H, J = 8.1
Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04 (br, 4H), 1.15 (m, 20H), 0.79 (t,
6H, J = 7.0 Hz), 0.66 (br, 4H).
PFV-DH4T. Yield: >99% (after precipitation in methanol). After
precipitation, the precipitate was dissolved in a small amount of CHCl3
and reprecipitated in hexane for further purification. Yield: 34 mg (68%). 1H
NMR (CDCl3) δ: [6.96ꢀ7.22, 2.80, 1.45, 0.93, dihexylquarterthiophene],
7.68 (d, 2H, J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04 (br, 4H), 1.15
(m, 20H), 0.79 (t, 6H, J = 7.0 Hz), 0.66 (br, 4H).
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dissolved in CHCl3 and filtered with glass filter, and the filtrate was
evaporated in vacuo. The resultant polymer was then dissolved in THF
and reprecipitated in hexane for further purification. Yield: 12 mg (40%).
1H NMR (CDCl3) δ: [7.00 (bs, 6H), 6.86 (s, 2H), 6.61 (d, J = 12.0 Hz,
1H), 6.50 (s, 3H), 6.02 (d, J = 12.8 Hz, 1H) sexithiophene], 7.68 (d, 2H,
J = 8.1 Hz), 7.52 (br, 4H), 7.27 (br, 2H), 2.04 (br, 4H), 1.15 (m, 20H),
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’ ASSOCIATED CONTENT
Supporting Information. 1H NMR spectra (in CDCl3 at
S
b
25 °C) for poly(fluorene-2,7-vinylene)s containing functional
groups at the chain ends, UVꢀvis and fluorescence spectra for
poly(fluorene-2,7-vinylene)s, and fluorescence decays for poly-
(fluorene-2,7-vinylene)s (1.0 ꢁ 10ꢀ6 M in THF). This material
is available free of charge via Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Tel þ81-42-677-2547, fax þ81-42-677-2547, e-mail ktnomura@
tmu.ac.jp.
’ ACKNOWLEDGMENT
The present research project was partly supported by Kansai
Research Foundation for Technology Promotion and Grant-in-
Aid for Challenging Exploratory Research (No. 21656209). S.K.
and K.N. express their thanks to Mr. Yasuo Okajima (Nara
Institute of Science and Technology) for measurements of
fluorescence lifetime.
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