A dual-polymer electrochromic device with high coloration efficiency and fast response time: Poly(3,4-(1,4-butylene-(2-ene)dioxy)thiophene)-polyaniline ECD

Article abstract of DOI:10.1002/asia.201000763

A new dual-polymer electrochromic device (ECD) composed of poly(3,4-(1,4-butylene-(2-ene)dioxy)thiophene) (PBueDOT) and polyaniline (PANI) with a hydrophobic molten salt electrolyte has been developed. To build this system, an alkylenedioxy ring in the BueDOT backbone was expanded to include a strongly electron-donating alkylenedioxy bridge, and the thickness and surface morphology of the corresponding PBueDOT film were controlled systematically. Not only the dual-electrochromic-polymer-electrode system, but also the expanded alkylenedioxy ring in the BueDOT backbone, synergistically improved the electrochromic performance. From the coloration efficiency (CE) value calculations, we found that the CE was enhanced up to 930 cm² C ^-1. Furthermore, these ECDs showed an extremely fast response time of less than 80 ms.

Full text of DOI:10.1002/asia.201000763

DOI: 10.1002/asia.201000763
A Dual-Polymer Electrochromic Device with High Coloration Efficiency and
Fast Response Time: PolyACTHNUTRGENUG(N 3,4-(1,4-butylene-(2-ene)dioxy)thiophene)–
Polyaniline ECD
Joo-Hee Kang,[a] Zhaochao Xu,[b] Seung-Min Paek,[c] Fang Wang,[a] Seong-Ju Hwang,[a]
Juyoung Yoon,*[a] and Jin-Ho Choy*[a]
Dedicated to Professor Eun Lee on the occasion of his retirement and 65th birthday
Abstract: A new dual-polymer electro-
chromic device (ECD) composed of
polyACHTUNGTRENNUNG(3,4-(1,4-butylene-(2-ene)dioxy)-
thiophene) (PBueDOT) and polyani-
line (PANI) with a hydrophobic molten
salt electrolyte has been developed. To
build this system, an alkylenedioxy ring
in the BueDOT backbone was expand-
ed to include a strongly electron-donat-
ing alkylenedioxy bridge, and the thick-
ness and surface morphology of the
corresponding PBueDOT film were
controlled systematically. Not only the
dual-electrochromic-polymer–electrode
system, but also the expanded alkyle-
nedioxy ring in the BueDOT back-
bone, synergistically improved the elec-
trochromic performance. From the col-
oration efficiency (CE) value calcula-
tions, we found that the CE was en-
Keywords: dual-polymers · electro-
hanced
up
to
930 cm2
Cꢀ1.
chromic devices
· fast response
Furthermore, these ECDs showed an
extremely fast response time of less
than 80 ms.
time · high coloration efficiency ·
PEDOT
Introduction
Semiconducting conjugated polymers have been widely used
as materials in light-emitting diodes,[1] solar cells,[2] electro-
chromic devices (ECDs),[3] field-effect transistors,[4] and
chemo-/biosensors.[5] Among them, poly(3,4-ethylenedioxy-
thiophene) (PEDOT) has been by far the most-extensively
studied as a cathode-coloring electrode owing to its small
electron band gap (Eg =1.6 eV at 775 nm), low redox poten-
tials (which confer not only exceptional stability to the oxi-
datively charged PEDOT, but also high conductivity), good
optical transparency in the visible spectrum, and fast re-
sponse time between the neutral and doped states.[6] Based
on these advantageous properties, many applications of
PEDOT have been rapidly developed.[7] For example,
PEDOT was suggested as a promising candidate for electro-
chromic applications, including smart windows, variable-re-
flectance mirrors, and optical lenses.[8] However, to meet the
increasing demand for ECDs with enhanced electrochromic
performance, several attempts have been made to design
new PEDOT-based materials.[9] As the most-representative
examples, Reynolds and co-workers[10] and Kumar and co-
workers[11] synthesized the EDOT analogs like 3,4-propyle-
nedioxythiophene (ProDOT) and 3,4-(1,4-butylenedioxy)-
thiophene (BuDOT) and studied the general factors influ-
[a] Dr. J.-H. Kang,+ F. Wang, Prof. Dr. S.-J. Hwang, Prof. Dr. J. Yoon,
Prof. Dr. J.-H. Choy
Center for Intelligent Nano-Bio Materials (CINBM)
Department of Chemistry and Nanoscience
and Department of Bioinspired Science (WCU)
Ewha Womans University
Seoul 120-750 (Korea)
Fax : (+82)2-3277-4305
E-mail: jhchoy@ewha.ac.kr
jyoon@ewha.ac.kr
[b] Dr. Z. Xu+
State Kye Laboratory of Fine Chemicals
Dalian University of Technology
Dalian 116012 (China)
[c] Prof. Dr. S.-M. Paek
Department of Chemistry and
Green-Nano Materials Research Center
Kyungpook National University
Taegu 702-701 (Korea)
[+] J.-H.K. and Z.X. contributed equally to this work: ECD=electro-
chromic device.
Supporting information for this article, including compound charac-
terization and NMR spectra, is available on the WWW under http://
dx.doi.org/10.1002/asia.201000763.
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FULL PAPERS
encing the electrochromic behaviors of corresponding poly-
mer ECDs. As a result, it has been clearly demonstrated
that attaching a strongly electron-donating alkylenedioxy
bridge across the 3- and 4-positions of the EDOT backbone
can prevent linkage defects during electrochemical polymer-
ization and add electron density to the aromatic ring. This is
the reason why the oxidation potentials of the monomer
and polymer were significantly lowered and why the stabili-
ty of the oxidized state and band-gap could be alter-
ed.[10–11,12e] Moreover, they found that larger alkylenedioxy
rings and more-bulky substituents resulted in the separation
of the polymer backbones from each other upon polymeri-
zation, which facilitated a more-expanded morphology and
allowed the counter-ions to be transported more easily
within the film. However, whilst substantial research has
been performed on EDOT derivatives, there are still some
drawbacks, such as poor synthetic processes and low mono-
mer yields. In addition, the syntheses of EDOT derivatives
with rings larger than 7-membered remain a challenge
owing to their associated torsional, transannular, and large-
angle strain.
Herein, we report the first large-ring EDOT derivatives
composed of eight-membered rings and substituent with
high synthetic yields. Moreover, of the derivatives, the 3,4-
(1,4-butylene-(2-ene)dioxy)thiophene (BueDOT) was elec-
trochemically polymerized on indium-doped tin-oxide (ITO)
glass with different thicknesses to identify the optimum
film-thickness and surface morphology of the electrode for
their high electrochromic properties. In order to maximize
the electrochromic properties, we constructed a dual-poly-
mer ECD, in which poly-BueDOT (PBueDOT) and polyani-
line (PANI) were employed as complementary coloring
electrodes. It has been suggested that the dual-polymer
ECD system gives rise to a synergistic effect on electro-
chromism owing to its electrochemical reversibility and
compatibility between the polymer electrodes.[12] The elec-
trochemical and optical behaviors of the dual-polymer
ECDs were investigated quantitatively with respect to the
thickness and surface morphology of new PEDOT-deriva-
tive electrodes.
er, recently, in order to increase yields and the number and/
or the length of functional groups, as well as stereochemical
tolerance, the Mitsunobu reaction[13] has been used as a key
step in the synthesis of a series of EDOT or ProDOT deriv-
atives because it allows the conversion of primary and sec-
ondary alcohols with nucleophiles into a variety of function-
al groups, such as esters, using a redox combination of a tri-
alkyl or triarylphosphine and a dialkyl azodicarboxylate. In
reports by the Reynolds[10d,g] and Bꢁuerle groups,[14] the key
step was the Mitsunobu reaction between diols and 3,4-dihy-
droxy-2,5-thiophenedicarboxylic acid diethyl ester
1 by
means of diethylazodicarboxylate/triphenylphosphine
(DEAD/TPP) and diisopropyl azodicarboxylate/tributyl-
phosphine (DIAD/TBP), respectively. However, the scope
of the Mitsunobu reaction is limited by the steric congestion
of the alcohols and the acidity of the nucleophiles (pKa <
13).
To overcome these drawbacks, Tsunoda et al. invented a
versatile Mitsunobu reagent system of N,N,N’,N’-tetramethy-
lazodicarboxamide (TMAD) and tributylphosphine (TBP)
that was successful for nucleophiles with a pKa value of up
to 13.5 and for a variety of steric environments.[15] This
TMAD/TBP system successfully provided large-ring EDOT
derivatives (Scheme 1, Table 1). The 8-membered com-
pounds 2a–c were obtained in excellent yields; these were
then saponified in NaOH/H2O followed by decarboxylation
with copper chromite in quinoline to yield the final mono-
mers 4a–c.
Scheme 1. Mitsunobu reaction of 1 with 1,n-alkyl diols for the large ring
3,4-ethylenedioxythiophenes (EDOTs).
Results and Discussion
New EDOT-Derivative Series
The most-common industrially applied synthetic route for
EDOT derivatives was the double Williamson etherification
of 3,4-dihydroxy-2,5-thiophenedicarboxylic acid diethyl ester
with 1,2-dihaloethanes under basic conditions.[6,10a–c] Howev-
Table 1. Mitsunobu reaction of 1 with 1,n-alkyl diols for the large-ring
3,4-ethylenedioxythiophenes (EDOTs).
Entry
1
R
Product
Yield [%][a]
78, 82, 66
M.p. [8C]
2a, 3a, 4a
80,>250,~[b]
2
3
2b, 3b, 4b
2c, 3c, 4c
86, 82, 73
97, 69, 44
146,>250,~[b]
148,>250,116
Abstract in Korean:
[a] Yield of isolated product. [b] Product was a pale-yellow oil.
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A Dual-Polymer Electrochromic Device
between the ITO substrate and the PBueDOT layer, which
suggests that the layer of electroactive polymer adhered
well to the electrode surface. Figure 1 (right) shows a sur-
face morphology comprised of bundled rod-like structures
for the PBueDOT layers. Based on the formation mecha-
nism for the interconnected and branched networks on the
surface of the layers, as well as the thickness of the deposit-
ed polymer film, Figure 1 (right) could be explained as fol-
lows:[17] 1) After a small amount of PBueDOT was deposit-
ed, the surface began to roughen, leading to an increase in
surface area and porosity (Figure 1a). 2) Upon further
PBueDOT deposition, the surface became increasingly
rough and eventually formed a loosely bound open struc-
ture, resulting in a highly porous surface area (Figure 1b).
3) Afterwards, as the deposition-time increased, the pores
were filled with additional PBueDOT, leading to a decrease
in surface roughness and porosity (Figure 1c). It has also
been reported that an increase in surface area and pore
growth of the electrode causes a lowering in the impedance,
as well as an improvement in conductivity. On the other
hand, if the surface morphology of the electrode begins to
become dense, the lithium diffusion onto the film becomes
more difficult.[17] Therefore, it is important to properly con-
trol the thickness and surface morphology of the electrode.
In this study, PBueDOT20 showed a maximum surface area
corresponding to the highest conductivity. This would lead
to a fast response time and an effective color change with a
small amount of power consumption, which is of particular
importance for display devices.
To investigate the influence of structural modification of
the PEDOT backbone on electrochemical and electrochro-
mic properties, we have studied the cyclic voltammetry
(CV) profiles and UV/Vis absorbance/transmittance spectra
for the PBueDOT electrodes. (see the Supporting Informa-
tion, Figure S1, Figure S2, and Figure S3) As revealed by the
voltammograms, all of the PBueDOT electrodes showed
similar curve shapes to that of the PEDOT electrode, thus
suggesting that as the potential of the electrode changed,
the intrinsic redox reactions of PBueDOT were found to be
similar to that of PEDOT. However, upon replacing the al-
kylene bridge of the EDOT backbone with a butylenes
group, positive shifts of two consecutive oxidation (approxi-
mately ꢀ0.8 V and 0 V) and reduction (approximately
ꢀ0.9 V and ꢀ0.3 V) peak potentials were induced, thereby
indicating that PBueDOT has a higher ionization potential
than PEDOT, owing to the higher resistance resulting from
the large alkylene dioxy rings between the polymer back-
bones, and that the neutral state should therefore be more
stable in air.[9e] On the other hand, for all of the PBueDOT
Electrochemical- and Electrochromic Properties of
PBueDOT ECDs
Of the synthetic monomers investigated, polyACTHNUGRTENUNG(3,4-(1,4-butyl-
ene-(2-ene)dioxy)thiophene (4a; PBueDOT) films were
only obtained from the potentiostatic method by applying
E=1.4 V for t=10–30 s. This result shows that monomers
with both eight-membered rings and other substituents on
the EDOT backbone are difficult to polymerize onto ITO
glass because of the low planarity of the alkylenedioxy ring
caused by the steric hindrance of the terminal groups and
poor adhesion to the ITO glass.[16] Considering the above
factors, steric hindrance and adhesion, upon electrochemical
polymerization of monomers onto ITO, we then selected
BueDOT as a model precursor to synthesize the polymer-
ECD and ascertained their physical and electrochromic
properties.
To elucidate the optimum thickness and surface morphol-
ogy of the electrode for high-quality ECDs, the thickness of
the deposited PBueDOT films was controlled by varying the
deposition time of the electrochemical polymerization (10 s,
20 s, and 30 s, hereafter abbreviated as PBueDOT10, PBue-
DOT20, and PBueDOT30, respectively). First, the thickness
and the detailed surface morphology of the PBueDOT
layers were investigated by cross-sectional scanning electron
microscope (SEM). As shown in Figure 1 (left), the thick-
ness of the PBueDOT10, PBueDOT20, and PBueDOT30
layers was determined to be approximately 100, 230, and
380 nm, respectively; this result indicates that the PBueDOT
layer became thicker upon lengthening the electrochemical
polymerization time. Furthermore, no defects were observed
ꢀ
electrodes, the absorbance of p p* transition was essentially
similar to that of the PEDOT electrode, as the color
changed from an almost transparent sky blue color in the
oxidized state to opaque dark blue color in the neutral
state.[8–9,18] Furthermore, the obtained optical band-gap
onsets of approximately 1.7 eV (725~745 nm in absorption
edge) were nearly identical to the PEDOT, thereby implying
that the ring-expansion of an alkylenedioxy ring in the
Figure 1. The thickness of PBueDOT electrodes with different electro-
chemical polymerization times (left; scale bar: 500 nm, magnification:
70 K) and the surface morphology (right; scale bar: 1 mm, magnification:
70 K): a) PBueDOT10, b) PBueDOT20, and c) PBueDOT30.
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J. Yoon, J.-H. Choy et al.
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EDOT backbone had little influence on the nature of the
polymer.[9,18]
Figure 2 shows the UV/Vis transmittance spectra, which
were obtained by applying a potential range between ꢀ0.6–
0.8 V for 30 seconds/half cycle. The voltage was controlled
From the CV and UV/Vis transmittance analysis, the colo-
ration efficiency (CE, h)—defined as the ratio of the change
in transmittance with log scale at a specified wavelength
(optical density change, DOD) to the integrated electronic
charge (Q)—was calculated for the individual PBueDOT
devices,[12] as summarized in Table 2. The CE values for
Table 2. Transmittance deference (DT), integrated charge (Q), optical
density (DOD), and coloration efficiency (h) of the devices in this study.
l[a]
DT [%]
Q
DOD[b]
CE, h [cm2 Cꢀ1
]
PBueDOT10
PBueDOT20
PBueDOT30
PBueDOT10-PANI
PBueDOT20-PANI
PBueDOT30-PANI
24
45
33
59
67
49
0.63
0.68
0.72
–
0.92
–
0.15
0.43
0.40
0.60
1.0
88.8
147
120
–
930
–
1.2
[a] l=613 nm for the single PBueDOT ECDs and l=630 nm for the
dual polymer PBueDOT - PANI ECDs. [b] The optical densities (DOD)
were measured under potentiostatic condition.
Figure 2. Percent UV/Vis transmittance (T) spectra of the PBueDOT-
PANI ECDs. The solid lines (ꢀ), dashed lines (–), and dotted lines (g)
represent the PBueDOT10-PANI, PBueDOT20-PANI, PBueDOT30-
PANI ECDs, respectively. The upper and lower lines show the bleached
and colored states for each sample.
PBueDOT10, PBueDOT20, and PBueDOT30 were deter-
mined to be 88.8 cm2 Cꢀ1, 147 cm2 Cꢀ1, and 120 cm2 Cꢀ1, re-
spectively, thereby indicating that highly porous PBue-
DOT20 exhibited the highest optical contrast with a small
amount of charge injection or extraction, thereby allowing
the faster switching rates in a narrow potential window.[10e]
This result is surely due to the fact that the thickness and
surface morphology of the electrode can influence the elec-
tronic interaction between intercalated lithium ions and col-
oration layer. In this regard, the electrochemical polymeri-
zation time for the PBueDOT electrode could be optimized
as 20 s, with a film thickness of approximately 230 nm,
which is in good accordance with the SEM results. Expan-
sion of the alkylenedioxy ring within the EDOT backbone
was made in an attempt to improve the optical properties of
the conducting polymer ECD, no remarkable enhancement
was observed in the CE value when compared to PEDOT or
PEDOT-derived ECDs reported previously.[9e,10a–b,e]
using the same method as described above. The percentage
transmittance difference (DT) at 630 nm for the PBue-
DOT20-PANI ECD with the best optical contrast among
the samples was determined to be 67%, which was signifi-
cantly higher than 45% for the single PBueDOT20 ECD;
this result indicated that the dual-polymer ECD could show
a synergetic electrochromic effect when they were properly
coupled.
As can be seen in Figure 3, 600 successive CV cycles were
scanned for the PBueDOT20 and PANI films as working
and counter electrodes, respectively, between ꢀ0.6 V–0.8 V
at a scanning rate of 50 mVsꢀ1. As revealed by the evolution
of the voltammograms, the PBueDOT20-PANI electrodes
PBueDOT-PANI Dual-Polymer ECDs
It has been suggested that a dual-polymer ECD system
using two complementary electrochromic electrodes could
enhance electrochemical and electrochromic performances,
such as optical contrast, switching time, and stability.[12]
Therefore, in this study, a polyaniline (PANI) film was used
as a complementary anodic electrode to the PBueDOT film
during the oxidation and reduction processes.[12a–b] The
thickness of the PANI layer was fixed to approximately
100 nm, which was found to be the optimal thickness based
on our previous studies.[17a] The complementary electro-
chemical and electrochromic properties of the present dual-
polymer ECDs were also investigated by CV profiles and
UV/Vis transmittance spectra, as summarized in Table 2.
Figure 3. Cyclic voltammograms for the PBueDOT20-PANI electrodes as
a function of repeated scans. The black cycles represent the first and the
last (600th) scans.
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A Dual-Polymer Electrochromic Device
exhibited typical characteristics of a dual-polymer ECD,
such as broad peak potentials of oxidation and reduction
within a common and narrow voltage range.[9c,17a] Indeed,
these electrodes nearly maintained their initial electroactivi-
ty even after 600 cycles. One thing to note here is that no
peaks were seen for side-reactions, indicating that the PBue-
DOT20 and PANI electrodes are an excellent complementa-
ry pair in the electrochemical and electrochromic reactions,
and thereby allowing an increase of the durability of
ECD.[19] The high Q value of 0.93 for the PBueDOT20-
PANI electrodes is an evidence that the reversible redox re-
actions are indeed occurring between these two conducting
polymer electrodes (see the Supporting Information, Fig-
ure S4).
current-response time for all samples of PBueDOT20-PANI
ECDs was reproducibly determined to be approximately
80 ms (Figure 4), which was significantly faster than that for
the previous PEDOT-PANI ECD or other conducting poly-
mer ECDs.[9–11] This observation can presumably be attribut-
ed to the ease of charge transport during doping/de-doping
resulting from porous polymer film morphology.[10b,18] Re-
viewing these results, we were able to greatly enhance the
electrochemical and electrochromic performances of
a
PEDOT-based electrode by expanding the alkylenedioxy
ring in the EDOT backbone.
Conclusions
The CE and response-time analysis provide direct evi-
dence for the advantages of not only the dual-polymer ECD
system but also the structural modifications in EDOT. Ac-
cording to the CE value calculation from the results of UV/
Vis transmittance spectra and CV profiles, a CE value of
930 cm2 Cꢀ1 for the PBueDOT20-PANI ECD was calculat-
ed, and found to be superior to that for the PEDOT-PANI
ECD or other PEDOT-based ECDs reported previous-
ly.[10–12,18] Such an enhancement of CE could be attributed to
the fact that the current amplitude of the PBueDOT20-
PANI electrodes was almost 10 times higher than that of
PEDOT-PANI electrodes, thereby implying that a smaller
electronic charge was required to affect bleaching or colora-
tion of the present sample, which would lead to faster
switching rates and more-pronounced optical changes in a
narrow potential window.[10b,e]
Finally, optical-switching studies for the PBueDOT20-
PANI ECDs were carried out by electric-circuit analysis. For
this experiment, the voltage for a square-wave function
((ꢁ0.9) V, 0.1 Hz) was employed in mimic switching with a
function generator. The dynamic profile of electric voltage
across the present samples corresponding to the current
through a capacitor and a resistor was monitored and digi-
talized through an oscilloscope. According to the theory of
determining an optical response based on the electric cur-
rent generated into the device during switching,[12a,20] the
A new series of large-ring alkoxy-substituted EDOT cyclic
analogs was synthesized successfully by a Mitsunobu reac-
tion, which provides a straightforward high yielding route to
modifying the EDOTs. The molecular structures of the de-
1
rivative series were characterized by H and 13C NMR spec-
troscopy, and by analysis of the melting point and mass
spectra. Of the series, a single polymer 3,4-(1,4-butylene-(2-
ene)dioxy)thiophene (PBueDOT) ECD was fabricated by
electrochemical polymerization. Spectro-electrochemical
analysis revealed that this ECD had an electronic band-gap
of ca. 1.7 eV (725~745 nm) and a coloration efficiency (CE)
of 147 cm2 Cꢀ1, which was similar to the parent PEDOT
ECD.
In the second part of the study, a dual-type complementa-
ry colored polymer ECD with enhanced coloration efficien-
cy and fast response time was developed by employing the
PBueDOT cathode with a controlled thickness and PANI
anode, in combination with a hydrophobic lithium electro-
lyte. As expected, increasing the alkylenedioxy ring-size
within the EDOT backbone improved the EC properties. In
the optimal case where the 230 nm thickness PBueDOT
electrode was used, the PBueDOT20-PANI ECD showed an
ideally matched integrated charge of Q=0.93 between
ꢀ0.6 V and 0.8 V, a noticeable increase in coloration effi-
ciency of 930 cm2 Cꢀ1, and a faster than 80 ms in response
time. Further investigations to enhance the optical contrast
and long-term stability of a conducting-polymer-based ECD
are underway, with an ultimate goal of constructing high
quality ECDs for various optical-device applications.
Experimental Section
Characterization of 3,4-Ethylenedioxythiophene (EDOT) Derivatives
Unless otherwise noted, materials were obtained from commercial sup-
pliers and used without further purification. Flash chromatography was
carried out on silica gel 60 (230–400 mesh ASTM; Merck). Thin layer
chromatography (TLC) was carried out using Merck 60 F254 plates with a
thickness of 0.25 mm. Preparative TLC was performed using Merck 60
F254 plates with a thickness of 1 mm. Melting points were measured using
a Bꢂchi 530 melting point apparatus. 1H NMR and 13C NMR spectra
were recorded using Bruker 250 MHz and Varian 500 MHz. Chemical
shifts were given in ppm and coupling constants (J) in Hz.
Figure 4. Dynamic voltage profile across the PBueDOT20-PANI ECDs.
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General Procedure for the Mitsunobu Reaction of Thiophene 1 and Diols
The polyaniline film was also fabricated by electrochemical polymeri-
zation onto ITO glass in a deposition solution including aniline monomer
(0.5m) and H2SO4 (1.0m) with deionized water under the deposition con-
dition of 0.75 V for 60 s.[12a] All electrodes were then washed repeatedly
with acetonitrile to remove the remaining monomer and oligomer on the
surface.
3,4-dihydroxy-2,5-thiophenedicarboxylic acid diethyl ester
1 (130 mg,
0.5 mmol), diol (0.5 mmol), and tributylphosphine (TBP; 0.31 mL,
1.26 mmol) were added to tetrahydrofuran (THF; 5 mL) in a two-necked
flask. With the exclusion of light, the system was then purged with argon.
N,N,N’,N’-Tetramethylazodicarboxamide (TMAD; 0.215 g, 1.25 mmol)
was dissolved in THF (10 mL) and added to the above solution over a
period of 30 min via syringe. After the addition, the mixture was warmed
to 608C for 36 h. The solvent was then removed under reduced pressure.
The crude product was purified by column chromatography on silica gel
(SiO2, CH2Cl2) to give 2 as a white solid.
2a: 78% yield. m.p. 808C. 1H NMR (CDCl3, 250 MHz): d=1.25 (t, J=
7.1 Hz, 6H), 4.20 (m, J=7.1 Hz, 4H), 4.95 (d, J=3.3 Hz, 4H), 5.87 ppm
(m, J=3.3 Hz, 2H). 13C NMR (CDCl3, 62.5 MHz): d=13.98, 60.91, 69.35,
117.48, 129.67, 150.45, 160.17 ppm. HRMS (EI) calcd for C14H16O6S [M]+
312.0668, found 312.0670.
Finally, a dual-polymer ECD (ITOjPBueDOTj jPANIjITO, PBueDOT-
PANI ECD) was prepared by assembling PBueDOT and PANI electro-
des with the hydrophobic lithium electrolyte (hereafter abbreviated as
LiTFSI-EtMeImTFSI), which was synthesized by mixing 10 wt% of lithi-
um trifluorosulfonimide (LiACTHNUTRGNE(UNG CF3SO2)2N, Li TFSI) and hydrophobic
molten salt (ethylmethylimidazolium trifluorosulfonimide, 1,3-EtMeIm
TFSI).[21]
Acknowledgements
General Procedure for the Preparation of 3
We gratefully acknowledge the financial support from the National Re-
search Foundation of Korea (NRF) (SRC program: 2011-0001340, 2011-
0001334, NRL program: 2010-0018895, and Basic Research Program:
2010-0024370), the WCU program (R31-2008-000-10010-0) and the State
Key Laboratory of Fine Chemicals of China (KF0809). J. H. Kang thanks
the Ministry of Education, Science and Technology for the Brain Korea
21 (BK21) fellowship.
Under argon, 2 (2.4 mmol) and NaOH (0.4 g, 10 mmol) were stirred in
water at 908C for 12 h. The resulting solution was cooled to room tem-
perature and acidified with HCl (1.0m) to precipitate a gray solid. The
product was filtered, washed with water, and dried under vacuum to give
3.
3a: 82% yield. m.p.>2508C. 1H NMR ([D6]DMSO, 250 MHz): d=5.02
(d, J=3.2 Hz, 4H), 6.03 (m, J=3.2 Hz, 2H), 13.36 ppm (s, 2H). 13C NMR
([D6]DMSO, 62.5 MHz): d=69.20, 118.15, 129.92, 150.03, 161.49 ppm.
HRMS (FAB) calcd for C10H8O6S [M]+ 256.0042, found 256.0043.
DMSO=dimethyl sulfoxide.
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2128
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Chem. Asian J. 2011, 6, 2123 – 2129

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Received: October 19, 2010
Published online: May 10, 2011
Chem. Asian J. 2011, 6, 2123 – 2129
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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