Preparation and characterization of poly[2,3-dimethyl-1-(4-thien-3-ylbenzyl)-1H-imidazol-3-ium] bis((trifluoromethyl)sulfonyl)imide

Article abstract of DOI:10.1021/ma011227x

A new 3-fluorophenylthiophene derivative bearing a cationic imidazolium group in the para position of the phenyl ring was synthesized by a multistep procedure which involves, in a key step, the reaction of 3-[4-(bromomethyl)phenyl]thiophene with 1,2-dimet

Full text of DOI:10.1021/ma011227x

Macromolecules 2002, 35, 4983-4987
4983
Preparation and Characterization of
Poly[2,3-dimethyl-1-(4-thien-3-ylbenzyl)-1H-imidazol-3-ium]
Bis((trifluoromethyl)sulfonyl)imide
Er ic Na u d in ,† Hoa n g An h Ho,‡ Ma r c-An d r e´ Bon in ,‡ Liva in Br ea u ,*,‡ a n d
Da n iel Be´la n ger *,†
De´partement de Chimie, Universite´ du Que´bec a` Montre´al (UQAM), Case Postale 8888, succursale
Centre-Ville, Montre´al, Que´bec, Canada H3C 3P8, and Laboratoire de Synthe`se Organique Applique´e,
De´partement de Chimie, UQAM, Case Postale 8888, succursale Centre-Ville, Montre´al,
Que´bec, Canada H3C 3P8
Received J uly 13, 2001; Revised Manuscript Received April 3, 2002
ABSTRACT: A new 3-fluorophenylthiophene derivative bearing a cationic imidazolium group in the para
position of the phenyl ring was synthesized by a multistep procedure which involves, in a key step, the
reaction of 3-[4-(bromomethyl)phenyl]thiophene with 1,2-dimethylimidazole. The bis[(trifluoromethyl)-
sulfonyl]imide (TFSI) salt was obtained by anion exchange of the imidazolium bromide precursor with
LiTFSI. The electrochemical oxidation of the title monomer in dichloromethane afforded an electronically
conducting polymer displaying both p- and n-doping redox waves. These redox processes were also
accompanied by change in absorption spectra that confirmed the modification of the electronic properties
of the polymer upon both p- and n-doping.
In tr od u ction
polymers having cations and anions ingress during n-
and p-doping, respectively should be solved.11
In the past 20 years, considerable effort has been
devoted to the electrochemical study of electronically
conducting polymers such as polypyrrole, polyaniline,
and polythiophene. These conducting polymers have
attracted great interest due to their potential use as
electrode materials in electrochromic devices, sensors,
light-emitting diodes, batteries, and supercapacitors.1
An interesting class of conducting polymers is the so-
called self-doped polymers for which the charge-com-
pensating ion is covalently bound to the polymer
backbone.2-8 The first self-doped polymers used sul-
fonate groups as ionic sites and part of the substituents
of polythiophene derivatives.3 An interesting charac-
teristic of these polymers, compared to their counterpart
having no such ionic sites, is that the charge compensa-
tion upon electrochemical oxidation involves the expul-
sion of cationic species instead of anion incorporation.
The presence of an ionic group on the polymer backbone
can also impart solubility properties to the polymer in
both the doped and undoped states. In addition, charged
redox active sites were also incorporated on the polymer
backbone.6
In our laboratory, we are interested in evaluating
conducting polymers as active electrode materials for
electrochemical supercapacitors.9 The use of self-doped
polymers for this purpose is limited to a polythiophene
derivative having a trimethylammonium group in the
para position of 3-phenylthiophene.10 Such a polymer
having a positively charged group covalently bound to
the thiophene unit is very interesting since charge
compensation in both the n- and p-doped states should
only involve anionic species. Consequently, problems
associated with depletion of salt from the electrolyte for
In this work, we report the synthesis of a 3-phenyl-
thiophene derivative having an imidazolium group in
the para position on the phenyl ring (8 in Scheme 1)
and preliminary electrochemical (cyclic voltammetry)
and spectroscopic (UV-vis) studies of the electrochemi-
cal generated polymer. Interestingly, this ionic group
forms ionic liquid in the presence of an appropriate
anions,12 and therefore, it might interesting to prepare
a polymer having a substituent which is the cationic
species of a salt. Such polymer might be also useful for
application requiring the presence of permanent positive
charge on the polymer backbone.
Exp er im en ta l Section
Ch em ica ls a n d Electr od es. Acetonitrile (HPLC grade)
was used as received. Tetraethylammonium bis((trifluoro-
methyl)sulfonyl)imide (Et4NTFSI) was synthesized from lithium
bis((trifluoromethyl)sulfonyl)imide (used as-received from 3M)
and tetraethylammonium bromide (Aldrich Chemical Co.).
3-Bromothiophene, 4-bromobenzyl alcohol, tert-butyldimethyl-
silyl chloride (TBDMSCl), tetrabutylammonium fluoride hy-
drate, phosphorus tribromide, imidazole, and 1,2-dimethyl-
imidazole were obtained from Aldrich Chemical Co. and were
used without further purification. THF and diethyl ether were
dried over sodium benzophenone ketyl anion radical and
distilled under a dry nitrogen atmosphere immediately prior
use. All reactions involving organometallic reagents were
carried out under nitrogen.
A 1 mm diameter platinum disk and platinum gauze were
used as working and counter electrode, respectively. The Pt
disk electrode was polished with 0.05 µm alumina slurry
(Buehler) and washed with water and cleaned ultrasonically
before use. A transparent tin oxide-coated glass electrode was
used for the spectroscopic measurements of the polymer. Prior
to polymer deposition, the transparent electrode was cleaned
by soaking in a 1 M HNO3 aqueous solution for 1 h. All
potentials were referenced against a 10-2 M Ag+/Ag electrode.
Syn th esis. The monomer 8 was prepared via a Kumada13
coupling reaction and was an adaptation of our previously
published procedure for ionic liquid12 (Scheme 1).
† De´partement de Chimie.
‡ Laboratoire de Synthe`se Organique Applique´e, De´partement
de Chimie.
* To whom all correspondence should be sent. E-mail:
belanger.daniel@uqam.ca; breau.livain@uqam.ca.
10.1021/ma011227x CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/21/2002

4984 Naudin et al.
Macromolecules, Vol. 35, No. 13, 2002
Sch em e 1
[(4-Br om oben zyl)oxy](ter t-bu tyld im eth yl)sila n e (2). To
a solution of 4-bromobenzyl alcohol, 1 (5.00 g, 26.7 mmol) in
CH2Cl2 (40 mL), was added imidazole (1.93 g, 28.3 mmol)
followed by TBDMSCl (4.27 g, 28.3 mmol) in three portions.
The mixture was stirred for 45 min and quenched by the
addition of Na2CO3 (10%), stirred for 20 min, and extracted
in CH2Cl2 (3 × 50 mL). The combined organic extracts were
washed with brine (20 mL), dried over MgSO4, filtered, and
evaporated. The crude yellow mass was dissolved into petro-
leum ether (40 mL), filtered, evaporated, and Kugelrohr
distilled, affording 7.15 g (89%) of 2 as a colorless oil; bp 131
°C (3 mmHg). 1H NMR (300 MHz, CDCl3, ppm): 7.46 (dt, J )
8.5, 1.9 Hz, 2H, H-3 + 5), 7.22 (bd, J ) 8.5 Hz, 2H, H-2 + 6),
4.71 (s, 2H, CH2O), 0.96 (s, 9H, 3 × CH3-C), and 0.12 (s, 6H,
2 × CH3-Si). 13C NMR (75.4 MHz, CDCl3, ppm): 140.40 (C),
131.23 (2 CH), 127.67 (2 CH), 120.54 (C), 64.27 (CH2), 25.88
(3 CH3), 18.34 (C), -5.31 (2 CH3-Si). GC-MS (70 eV) m/z (rel
int): 302 (1%, M+81Br); 300 (1%, M+79Br); 245 (100%, 81Br);
243 (100%, 79Br), 215 (26%, M+81Br); 213 (26%, M+79Br), 171
(47%, 81Br); 169 (47%,79Br), and 90 (10%).
EtOAc, 95:5) provided 5 (310 mg, 1.63 mmol, 94%) as a white
shiny solid; mp 154-155 °C. IR (cm-1): 3315, 3216, 3095, 2912,
2855, 1046, 1011, 866, 824, 774 cm-1 1H NMR (300 MHz,
.
CDCl3, ppm): 7.61 (dt, J ) 8.2, 1.9 Hz, 2H, H-3), 7.47 (t, J )
2.2 Hz, 1H, H-2′), 7.42 (m, 4H, H-3 + 4,5), 4.73 (s, 2H, CH2O),
and 1.72 (s, 1H, OH). 13C NMR (75.4 MHz, CDCl3, ppm):
141.95 (C), 139.68 (C), 135.27(C), 127.49 (2 CH), 126.60 (2CH),
126.28 (CH), 126.26 (CH), 120.30 (CH), and 65.11 (CH2OH).
GC-MS (70 eV) m/z (rel int): 190 (M+ 100), 173 (25), 161 (60),
128 (45), 115 (29), and 77 (9). Anal. Calcd for C11H10S: C, 69.4;
H, 5.30; S,16.85. Found: C, 69.10; H, 5.38; S, 16.83.
3-[4-(Br om om eth yl)p h en yl]th iop h en e (6). To a stirred
solution of [4-(3-thienyl)phenyl]methanol (5) (0.64 g, 3.36
mmol) in 20 mL of freshly distilled ether held at 0 °C was
added, dropwise, phosphorus tribromide (0.95 mL, 10 mmol).
The mixture was then stirred at room temperature for 24 h
at which time was added a saturated aqueous solution of
sodium carbonate (20 mL). The aqueous layer was extracted
with ether, and the combined ethereal layers were washed
with water, dried (MgSO4), filtered, and evaporated under
reduced pressure to yield 0.43 g (51%) of 6 as a white powder.
1H NMR (CD3Cl) δ: 7.58 (dt, J ) 8; 2 Hz, 2H); 7.47 (dd, J
) 2.6; 1.6 Hz, 1H); 7.44 (dt, J ) 8; 2 Hz, 2H); 7.4 (d, J ) 2.6
Hz, 1H); 7.39 (d, J ) 1.6 Hz, 1H); 4.54 (s, 2H). 13C NMR (CD3-
Cl) δ: 141.60; 136.54; 135.99; 129.55 (2C); 126.80 (2C); 126.40;
126.22; 120.74; 33.41. GC-MS (70 eV) m/z (rel int): 254 (3%,
M+81Br); 252 (3%,M+79Br); 173 (100%, M+ - Br,), 128 (8%), 86
(10%).
ter t-Bu tyld im eth yl[4-th ien -3-ylben zyl)oxy]sila n e (4). A
solution of 4-benzyloxy-(tert-butyldimethyl)silylmagnesium
bromide, 3, was freshly prepared from [(4-bromobenzyl)oxy]-
(tert-butyldimethyl)silane (2) (0.904 g, 3.0 mmol) and magne-
sium turnings (0.108 g, 4.5 mmol) in refluxing tetrahydrofuran
(10 mL) for 2 h. After cooling the Grignard reagent 3 to room
temperature, 3-bromothiophene (0.28 mL, 3.0 mmol) was
added along with NiCl2(dppe) (55 mg, 0.10 mmol), which was
added four times at intervals of 5 min. The mixture was
refluxed for 3 h and then was carefully hydrolyzed with H2O
(5 mL) followed by ammonium chloride saturated solution (25
mL). The mixture was diluted with ether (40 mL), and the
organic layer was separated. The aqueous layer was extracted
with ether (3 × 15 mL), and the combined organic layers were
dried over MgSO4. The solvent was removed under reduced
pressure, and the dark crude residue was purified on a plug
of silica gel (5 g) using petroleum ether. The yellow mass thus
obtained was separated on silica gel (chromatotron, 2 × 4 mm,
petroleum ether) to afford 610 mg (67%) of the title compound,
4, as a colorless crystalline solid; mp: 76-79 °C. IR (cm-1):
3092, 2925, 2850, 1466, 1255, 1097, 1051, 864, 836 , 776, and
2,3-Dim e t h yl-1-(4-t h ie n -3-ylb e n zyl)-1H -im id a zol-3-
iu m Br om id e (7). A solution of 6 (0.21 g, 0.83 mmol) and
1,2-dimethylimidazole (0.09 g, 0.91 mmol) in toluene (10 mL),
was refluxed for 3 h, and the white crystals formed were
decanted from the hot solution. The toluene phase was
removed via cannula. The solid product was washed four times
with ethyl acetate and dried under reduced pressure to yield
0.29 g (100%) of 7 as a white powder.
1H NMR (DMSO-d6) δ: 7.89 (dd, J ) 2.8; 1.4 Hz, 1H); 7.74
(m, 3H); 7.64 (m, 2H); 7.55 (dd, J ) 5.1; 1.4 Hz, 1H); 7.36 (d,
J ) 8 Hz, 2H); 5.41 (s, 2H); 3.75 (s, 3H); 2.60 (s, 3H).
2,3-Dim e t h yl-1-(4-t h ie n -3-ylb e n zyl)-1H -im id a zol-3-
iu m Bis((tr iflu or om eth yl)su lfon yl)im id e (8). To a stirred
solution of 7 (0.29 g, 0.83 mmol) in deionized water (6 mL)
was added lithium bis((trifluoromethyl)sulfonyl)imide (0.26 g,
0.91 mmol). The reaction mixture was refluxed for 4 h. The
white powder was decanted, filtered, washed four times with
deionized water, and then dried over P2O5 under reduced
pressure to yield 0.34 g (75%) of 8 as a white powder.
UV (DMSO) λmax: 267 nm. 1H NMR (DMSO-d6) δ: 7.89 (dd,
J ) 3.0; 1.4; Hz, 1H); 7.74 (d, J ) 8 Hz, 2H); 7.71 (d, J ) 2.2
Hz, 1H); 7.64 (m, 2H); 7.55 (dd, J ) 5.2; 1.4 Hz, 1H); 7.35 (d,
J ) 8 Hz, 2H); 5.44 (s, 2H); 3.81 (s, 3H); 2.62 (s, 3H). 13C NMR
(DMSO-d6) δ: 144.88; 140.90; 135.56; 133.51; 128.69 (2C);
127.57; 126.82 (2C); 126.39; 122.93; 121.80; 121.46; 119.50 (q,
J C-F ) 320 Hz, 2C); 50.59; 35.07; 9.71. Anal. Calcd for
1
767. H NMR (300 MHz, CDCl3, ppm): 7.59 (bd, J ) 8.4 Hz,
2H, H-3,+ 5), 7.45 (dd, J ) 2.2, 1.9 Hz, 1H, H-2′), 7.41-7.39
(m, 2H, H-4′, + 5′), 7.37 (d, J ) 8.4 Hz, 2H, H-2 + 6), 4.78 (s,
2H, CH2O), 0.98 (s, 9H, 3 × CH3-C) 0.72 (s, 1H, OH), and
0.13 (s, 6H, 2 × CH3-Si). 13C NMR (75.4 MHz, CDCl3, ppm):
142.24 (C), 140.36 (C), 134.50 (C), 126.50 (2 CH), 126.33 (CH),
126.28 (2 CH), 126.10 (CH), 119.96 (CH), 64.74 (CH2), 25.96
(3 CH3), 18.42 (C), -5.23 (2 CH3-Si). GC-MS (70 eV) m/z (rel
int): 304 (M+ 2), 247 (22), 173 (100).
(4-Th ien -3-ylp h en yl)m eth a n ol (5). A solution of 4 (530
mg, 1.74 mmol) in THF (10 mL) was treated with Bu4NF‚H2O
(820 mg), and the mixture was stirred at 25 °C for 45 min.
The resultant solution was diluted with water (25 mL) and
EtOAc (25 mL). The phases were separated, and the aqueous
one was extracted with EtOAc (3 × 15 mL). The combined
organic extract were dried (MgSO4), filtered, and concentrated
in vacuo. Chromatography (chromatotron, SiO2, CH2Cl2/
C
18H17N3O4F6S3: C, 39.34; H, 3.12; N, 7.65; S, 17.5. Found: C,
39.33; H, 2.98; N, 7.68; S, 17.7.
P r oced u r e a n d Ap p a r a tu s. Polymer films were prepared
galvanostatically on a Pt disk by anodic oxidation at an

Macromolecules, Vol. 35, No. 13, 2002
Preparation and Characterization of Poly-8 4985
appropriate current density from a monomer solution in
dichloromethane or acetonitrile containing 0.5 M Et4NTFSI.
The electrochemical studies were performed with an electro-
chemical cell inside a drybox by using a potentiostat model
1287 Solartron electrochemical interface coupled to a PC with
Corrware Software for Windows (Scribner Associates, version
2.1b).
1H NMR spectra were recorded using a Varian 300 MHz
spectrometer. Chemical shifts are reported in parts per million
(δ), and the signals were designated as follows: s (singlet), d
(doublet), t (triplet), and m (multiplet). Melting points were
determined with a Fisher-J ohns melting point apparatus and
are uncorrected. Mass spectra were obtained using a GC-MS
(GCD plus gas chromatography-electron ionization detector,
HPG 1800A GCD system) equipped with a 5% cross-linked Ph
Me silicone HP 19091 J -433 column. Infrared spectra were
recorded on a Perkin-Elmer 1600 FTIR instrument. Separa-
tions were carried out on silica gel (7749 Merck) using circular
chromatography (chromatotron, model 7924, Harrison Re-
search). In situ UV-vis spectra were measured with
a
Hewlett-Packard spectrophotometer (model HP 8452A). For
the spectroscopic measurements, the polymer was electro-
chemically grown on a tin oxide-coated glass electrode at a
current density of 14 mA/cm2 from a 82 mM monomer solution
containing 0.5 M Et4NTFSI in dichloromethane.
F igu r e 1. Cyclic voltammetry for the monomer (82 mM) at a
platinum electrode in 0.5 M TEATFSI/dichloromethane. Scan
rate ) 50 mV/s. The cycle numbers of the successive cyclic
voltammograms are indicated in the figure.
Resu lts a n d Discu ssion
Electr och em ica l Oxid a tion of th e Mon om er . The
electrochemical oxidation of the monomer salt 8 (82 mM)
at a platinum electrode was investigated by cyclic
voltammetry at a scan rate of 50 mV/s in nonaqueous
media (acetonitrile or dichloromethane) containing 0.5
M TEATFSI. The first cyclic voltammogram in dichloro-
methane shows an irreversible anodic wave at 1.49 V,
which corresponds to the formation of the cation radical.
The oxidation potential can be also obtained from the
potential-time curve recorded during galvanostatic
deposition. In this case, the oxidation potential varies
from 1.28 V for a deposition current density of 0.3 mA/
cm2 to 1.41 V for 1.2 mA/cm2. These values are notice-
ably higher than those found for 3-phenylthiophene9e,14
and reflects the steric and inductive effects of the
imidazolium substituent. In a recent study on substi-
tuted 3-arylthiophene, the variation of the oxidation
potential of the monomer was explained by the reso-
nance and inductive effects of the substituents (e.g.,
methyl, fluorine, methylsulfonyl) on the phenyl ring.14
The inductive effect of the imidazolium group could be
operative despite the presence of the intervening me-
thylene group that linked it to the phenyl ring. The
oxidation potential of monomer 8 is significantly more
positive than that reported for a strong EWG group,
suggesting that steric effects might be significant. Thus,
the observed shift of the oxidation potential of the
monomer can be explained by both inductive and steric
effects of the imidazolium moiety. In addition, the
counterion (TFSI-) of the cationic thiophene monomer
8 may also contribute to the steric effect, especially if
the monomer salt is not completely dissociated. This is
suggested by the lower oxidation potential (1.35 V) for
monomer 8 oxidation in acetonitrile which has a higher
dielectric constant than dichloromethane.
F igu r e 2. Cyclic voltammogram for poly-8 in 0.5 M Et4NTFSI/
dichloromethane at a scan rate of 100 mV/s.
the deposition of a polymer at the electrode surface.
Finally, a stable polymer film cannot be grown in
acetonitrile due to the high solubility of the oligomers
which prevented polymer formation.
Electr och em istr y of th e P olym er . Figure 2 shows
the cyclic voltammogram for poly-8 in 0.5 M Et4NTFSI/
dichloromethane that is characterized by the redox
waves centered for p-doping at 0.65 V and n-doping at
-2.0 V. The cyclic voltammogram of poly-8, grown in
dichloromethane and transferred in acetonitrile, is
similar to that of Figure 2 although a quick decay of
the redox waves is observed upon potential cycling. In
comparison to PPT or PFPT, the redox waves potential
are barely affected for poly-8. This is to be contrasted
with the difference noted above for the oxidation of the
corresponding monomers. A similar trend was recently
noticed for a series of substituted arylthiophene and
poly(arylthiophene)s.14 The electrochemical band gap of
about 1.7 eV that could be deduced from the difference
between the onset of the p- and n-doping is in reason-
ably good agreement with that of PPT.9e The fact that
Figure 1 shows successive cyclic voltammograms
between 0 and 1.4 V with the onset of monomer
oxidation at about 1.3 V. On the return scan, a reduction
wave is apparent at 0.64 V and is attributed to the
reduction of the polymer that was formed on the forward
scan. On the second scan, the oxidation of the polymer
gives rise to an additional anodic wave at 0.65 V. Both
polymer waves grow upon continuous cycling, indicating

4986 Naudin et al.
Macromolecules, Vol. 35, No. 13, 2002
of 0.1 and -1.5 V) have an absorption maximum around
515 nm, which is attributed to the π-π* transition of
the polymer. The oscillator strength of this band de-
creases upon increasing the oxidation potential, but
another transition is observed at lower energy (around
800 nm). Also, the peak at 515 nm shifts toward higher
energy by increasing the oxidation level. Such modifica-
tions of the spectra are commonly observed for poly-
thiophene derivatives and are related to the formation
of radical cations and dimerized radical cations upon
oxidation of the polymer.16-18 Similar features are seen
in the absorption spectra during the reduction of the
polymer (Figure 4), but a close look at the evolution of
the spectra with electrode potentials revealed some
differences. A decrease of the intensity of the main
absorption band is noticed upon reduction. On the other
hand, and in contrast to what was observed for the
p-doped state, the main transition shifts to lower energy,
and the bleaching of this band is not as complete. Also,
no well-defined band seems to be apparent above 650
nm despite that a constant increase of absorbance is
found in this spectral region. These observations indi-
cate that the n-doped polarons are relatively unstable
compared to the p-doped polarons. The optical band gap
was also evaluated by considering the onset of the π-π*
transition.9e A value of 1.7 eV was determined and is
in very good agreement with that obtained from the
electrochemical data.
F igu r e 3. In situ absorption spectra dependence on applied
potential for poly-8 on a tin oxide electrode in 0.5 M Et4NTFSI/
dichloromethane. The oxidation potential ranged from 0.1 to
0.9 V vs Ag/Ag+.
Con clu sion
In this work, we have shown that a bis(trifluorom-
ethyl)sulfonyl)imide salt of a 3-phenylthiophene deriva-
tive bearing a positively charged imidazolium group can
be oxidized in dichloromethane to yield an electroactive
polymer. The resulting polymer displayed both p- and
n-doping redox activity. The presence of a permanent
positive charge on the polymer may be useful for the
development of electrochemical supercapacitors where
charge compensation of the oxidized or reduced may be
mainly achieved by anions from the supporting electro-
lyte.10 In a recent study, Ferraris and co-workers have
presented cyclic voltammetry and electrochemical quartz
crystal microbalance studies for a poly(3-phenylthio-
phene) derivative having a trimethylammonium sub-
stituent in the para position.10a Their data suggest that
anions are primarily involved in the charge compensa-
tion mechanism as mass loss and mass gain have been
recorded during n- and p-doping, respectively. Further
studies on charge transport and conductivity of the
polymer will be required to get more insight into the
usefulness of poly-8 for some potential applications.
F igu r e 4. In situ absorption spectra dependence on applied
potential for poly-8 on a tin oxide electrode in 0.5 M Et4NTFSI/
dichloromethane. The reduction potential ranged from -1.5
to -2.3 V vs Ag/Ag+.
similar band gap values are found for PPT and poly-8
may seem at odd with the cyclic voltammetry data of
the monomer and the spectroscopic data. However, the
higher oxidation potential and reactivity of monomer 8
in comparison to 3-phenylthiophene apparently led to
polymers with similar conjugation length despite the
steric demand of the imidazolium group.
A meaningful doping level could not be determined
due to the low polymerization efficiency that is evi-
denced by the formation of highly colored oligomers
diffusing in the deposition solution. The well-defined
prepeaks that are clearly observed at 0.09 and -1.72 V
are absent when the potential cycling is limited to only
the p- or n-doping states. The presence of these prepeaks
on the cyclic voltammogram of polythiophene deriva-
tives is well documented in the literature9a,b,15 and will
not be discussed further here.
Ack n ow led gm en t. This work was partially sup-
ported by Strategic and Research Grants from the
Natural Sciences and Engineering Research Council
(NSERC) of Canada and from “le Fonds FCAR-Soutien
aux Equipes” of the Que´bec government. M.-A.B. thanks
NSERC for the award of an Undergraduate Student
Research fellowship, and E.N. also acknowledges the
financial contribution of UQAM for a fellowship.
UV-vis Sp ectr oscop y of th e P olym er for th e p -
a n d n -Dop ed Sta tes. Figures 3 and 4 show a series of
in-situ absorbance spectra of poly-8 films on a tin oxide
electrode in 0.5 M Et4NTFSI/dichloromethane taken at
different applied voltages for both the p- and n-doped
states, respectively. The neutral films (applied potential
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