Preparation and properties of a novel polythiophene, poly[(3- hexyliminomethyl)thiophene] with a high regioregularity

Article abstract of DOI:10.1002/pola.24536

Poly[(3-hexyliminomethyl)thiophene]s (P3HITs) were synthesized from the polymerizations of 2,5-dibromo-(hexyliminomethyl)thiophene and 5-bromo-2-iodo-3-(hexyliminomethyl)thiophene by Grignard metathesis method. The corresponding P3HITs with low regioregularity (70%) and high regioregularity (95%) were obtained, respectively. UV-vis and photoluminescence spectra of P3HIT were dependent on the regioregularity and solvent polarity. By hydrolysis of the imino groups in the side chains under acidic conditions, P3HIT was successfully converted into the polythiophene (P3TCHO) having aldehyde groups. This transformation was also performed facilely by exposing the P3HIT film to HCl gas to give the polythiophene having aldehyde moiety. The reverse way from aldehyde to imine was also successfully demonstrated by treating the film with triethylamine vapor.

Full text of DOI:10.1002/pola.24536

Preparation and Properties of a Novel Polythiophene,
Poly[(3-hexyliminomethyl)thiophene] with a High Regioregularity
KWANG-HOI LEE, KAZUHIDE MORINO, ATSUSHI SUDO, TAKESHI ENDO
Molecular Engineering Institute, Kinki University, 11-6 Kayanomori, Iizuka, Fukuoka, Prefecture 820-8555, Japan
Received 30 August 2010; accepted 2 December 2010
DOI: 10.1002/pola.24536
Published online 10 January 2011 in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: Poly[(3-hexyliminomethyl)thiophene]s (P3HITs) were
synthesized from the polymerizations of 2,5-dibromo-(hexyl-
iminomethyl)thiophene and 5-bromo-2-iodo-3-(hexylimino-
methyl)thiophene by Grignard metathesis method. The
corresponding P3HITs with low regioregularity (70%) and high
regioregularity (95%) were obtained, respectively. UV–vis and
photoluminescence spectra of P3HIT were dependent on the
regioregularity and solvent polarity. By hydrolysis of the imino
groups in the side chains under acidic conditions, P3HIT was
successfully converted into the polythiophene (P3TCHO) hav-
ing aldehyde groups. This transformation was also performed
facilely by exposing the P3HIT film to HCl gas to give the poly-
thiophene having aldehyde moiety. The reverse way from alde-
hyde to imine was also successfully demonstrated by treating
the film with triethylamine vapor. VC 2011 Wiley Periodicals, Inc.
J Polym Sci Part A: Polym Chem 49: 1190–1194, 2011
KEYWORDS: conjugated polymers; functionalization of poly-
mers; polythiophene; UV-vis spectroscopy
INTRODUCTION Polythiophenes (PTs) have been studied
edge, the preparation of P3TCHO as a homopolymer has not
been reported so far, probably due to a poor solubility of a
resulting polymer in organic solvents. Copolymers involving
P3TCHO and soluble long alkyl substituted-thiophene unit
intensively as functional polymers for organic optoelectronic
1
devices such as organic thin film transistors, light-emitting
2
3
diodes, and polymer solar cells. Poly(3-hexylthiophene)
P3HT) has been used for the fabrication of those devices
8
(
have been reported.
due to its thermal stability, processibility based on its high
solubility in organic solvents, and high charge mobility. Cur-
rently, further improvement of properties for such optoelec-
tronic devices has been attempted by side chain modifica-
We here report synthesis of a new PT derivative, poly[(3-hex-
yliminomethyl)thiophene] (P3HIT) by Grignard metathesis
(
GRIM) method, which is frequently used for synthesizing
9
P3HT. By using an appropriately designed dihalothiophene
monomer, a highly regioregular P3HIT was successfully syn-
thesized. Another highlight of this report is the utilization of
the obtained P3HIT as a precursor for a regioregular
P3TCHO. By treating a P3HIT film under acidic conditions,
hydrolysis of the imino pendants into aldehyde pendants
was achieved, to give a film of P3TCHO successfully.
4
tions and control of regioregularity of PTs.
PTs having imino groups in the side chains have attracted
interests as new candidate materials for photovoltaic and
electroluminescent devices. Sharma et al. have fabricated
photovoltaic devices with poly(phenyl azo methane thio-
phene) prepared by the oxidative polymerization of the cor-
5
responding thiophene monomer using ferric chloride. How-
ever, its molecular structure and molecular weight have not
been clarified fully. Brembilla et al. prepared conducting
polymer films by electrochemical polymerizations of various
EXPERIMENTAL
Materials
6
thiophene monomers. However, the corresponding conduct-
THF was dried over sodium/benzophenone ketyl and dis-
tilled just before use. Chloroform was distilled over CaH2.
DMF, methanol, and dichloromethane were used as received.
ing polymer was not formed with that method probably due
to rigid Schiff base. Somanathan et al. have reported the
preparation of PTs functionalized with benzothiazole groups
linked by ACH ¼¼ NA and their application to electrolumines-
3
-Thiphenecarboxaldehyde, isopropyl magnesium chloride (2
M solution in THF; Aldrich chemical), iodobenzene diacetate
TCI chemical), iodine, n-hexyl amine, NiCl (dppp), and NBS
7
cent devices.
(
2
Poly(3-thiophenecarboxaldehyde) (P3TCHO) is one of simple
structural PT derivatives. However, to the best of our knowl-
(Wako chemical) were used without further purification. 5-
Bromo-3-thiophenecarboxaldehyde (2) and 2,5-dibromo-3-
Additional Supporting Information may be found in the online version of this article. Correspondence to: T. Endo (E-mail: tendo@mol-eng.fuk.
kindai.ac.jp)
Journal of Polymer Science Part A: Polymer Chemistry, Vol. 49, 1190–1194 (2011) V
2011 Wiley Periodicals, Inc.
C
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ARTICLE
thiophenecarboxaldehyde (3) were prepared according to
the literature.
26.98, 30.80, 31.62, 61.71, 79.67, 116.51, 129.62, 142.55,
155.31.
1
0
Instruments
Preparation of LR-P3HIT
To a solution of 5 (0.71 g, 2.00 mmol) in THF (20 mL) was
1
13
H and C NMR spectra were recorded on a Varian INOVA
00 NMR spectroscopy using tetramethylsilane as an inter-
i
4
added 2.0 M THF solution of ProMgCl (1.0 mL, 2.0 mmol) at
ꢀ
ꢀ
nal standard in chloroform-d (CDCl ). IR spectrum was
3
0
C. After the solution was stirred for 30 min at 0 C,
recorded from Thermo fishier Scientific NICOLET iS10. UV–
vis spectroscopy was measured on JASCO V570 spectrometer.
Photoluminescne spectra were obtained on Hitachi F-2500
NiCl (dppp) (5.4 mg, 0.010 mmol, 0.5 mol % to 5) was
2
added. After refluxed for 20 h, the solution was poured into
MeOH (200 mL). The precipitate was collected by filtration.
The obtained crude polymer was purified by column chro-
fluorescence spectrophotometer. Number-average (M ) and
n
weight-average (M ) molecular weights were determined by
w
matography (silica gel treated by Et N) using THF as an elu-
3
size exclusion chromatography with TOSOH HLC-8120GPC in
THF with a calibration curve of polystyrene standards.
P3HIT film was prepared on a glass substrate with a spin
coater (700 rpm for 10 s and then 3000 rpm for 60 s) using
ent to give 0.23 g (60%) of LR-P3HIT as a purple solid.
Preparation of HR-P3HIT
HR-P3HIT was prepared by the same procedure for the
preparation of LR-P3HIT using 6 (0.80 g, 2.00 mmol) in 64%
yield as a purple solid.
10 mg/mL solution.
Preparation of 5-bromo-2-iodo-3-
thiophenecarboxaldehyde (4)
1
H NMR (CDCl ): d(ppm) 0.90 (t, J ¼ 7.0 Hz, ACH , 3H),
3
3
1
.33–1.41 (m, ACH A, 6H), 1.70–1.75 (m, ACH A, 2H), 3.67
2
2
To a solution of 4 (0.88 g, 4.61 mmol) in CH Cl2 (10 mL)
2
(
t, J ¼ 6.6 Hz, ¼¼ NCH
2
A, 2H), 7.73 (s, thiophene proton, 1H),
was added iodine (0.59 g, 2.31 mmol) and of PhI(OAc)2
1
3
ꢀ
8.61 (s, ACH ¼¼ NA, 1H); C NMR (CDCl
3
): d(ppm) 14.11,
2.65, 27.10, 30.96, 31.69, 62.18, 127.96, 132.53, 137.00,
38.62, 153.93.
(
0.81 g, 2.51 mmol) at 0 C. After the solution was stirred
2
1
for 3 h at room temperature 10 wt % Na S O aqueous solu-
2
2 3
tion (20 mL) was added to the reaction mixture. After the
mixture was stirred for 5 min, the crude product was
extracted with ethyl ether (50 mL ꢁ 3). After the ethereal
RESULTS AND DISCUSSION
layer was dried over MgSO , the solvent was removed under
4
Preparation of P3HITs
reduced pressure. The residue was purified by column chro-
The synthetic route to dihalothiophene monomers 5 and 6 is
shown in Scheme 1. Bromination of 3-thiophenecarboxalde-
hyde (1) with 1 equiv of NBS afforded 5-bromo-3-thiophene-
carboxaldehyde (2) in 51% yield. The reaction of 1 with
excess amount of NBS gave 2,5-dibromo-3-thiophenecarbox-
aldehyde (3) in 87% yield. 5-Bromo-2-iodo-3-thiophenecar-
boxaldehyde (4) was readily prepared by iodination of 2
using iodobenzene diacetate and iodine. The aldehyde
groups of 3 and 4 were converted into the corresponding
imino group by treatment with n-hexylamine to afford 5
(96% yield) and 6 (96% yield), respectively.
matography (silica gel) using hexane/CHCl (1:1) as an elu-
3
ent to afford 1.1 g (76%) of 4 as a pale yellow solid.
ꢀ
1
Mp. 98.5–99.0 C; H NMR (CDCl ): d(ppm) 7.29 (s, thio-
3
1
3
phene proton, 1H), 9.56 (s, ACHO, 1H); C NMR (CDCl3):
d(ppm) 87.87, 117.91, 129.39, 142.32, 185.62.
2,5-Dibromo-3-(hexyliminomethyl)thiophene (5)
To a solution of 2 (2.00 g, 7.42 mmol) in of MeOH (50 mL)
was added of n-hexylamine (0.75 g, 7.42 mmol) at room
temperature. After the solution was refluxed for 20 min, the
solvent was removed under reduced pressure to give 2.5 g
Before the investigation on the GRIM polymerizations of 5
and 6, their reaction behaviors with isopropyl magnesium
chloride (IPMC) were investigated (Scheme 2). Compound 5
was treated with an equimolar amount of IPMC for 30 min
(96%) of 5 as colorless oil [The purity checked by gas chro-
matography (GC) was 99%].
1
H NMR (CDCl ): d(ppm) 0.89 (t, J ¼ 6.8 Hz, ACH , 3H),
3
3
ꢀ
1
.29–1.36 (m, ACH A,6H), 1.62–1.68 (m, ACH A, 2H), 3.57
at 0 C. A small portion of the mixture taken by a syringe
2
2
(
dt, J ¼ 7.0 and 1.2 Hz, ¼¼ NCH A, 2H), 7.41 (s, thiophene
was treated with water to protonate anionic species. The
resulting mixture was analyzed by GC (see Fig. S1 in the
Supporting Information) and H NMR (see Fig. S2 in the Sup-
2
1
3
proton, 1H), 8.15 (t, J ¼ 1.2 Hz, ACH ¼¼ NA, 1H); C NMR
1
(CDCl ): d(ppm) 14.06, 22.59, 26.97, 30.78, 31.16, 61.83,
3
1
12.08, 115.10, 129.13, 152.84, 163.24.
porting Information). It was found that the corresponding
0
0
monobromothiophenes A and B were formed in a molar ra-
tio of 7:3 as the consequence of the formation of the Gri-
gnard reagents A and B in 7:3. There was no indication of an
unfavorable consumption of the imine moiety by its reaction
with IPMC. The predominant formation of A would reflect
the regioselective metalation assisted by the Lewis basic im-
ino moiety. Highly selective metalation was achieved by
treatment of 6 with IPMC. The selective reduction of the
iodo atom at 2-position permitted the exclusive formation of
A, which was confirmed by observation of the selective
5
-Bromo-2-iodo-3-(hexyliminomethyl)thiophene (6)
Compound 6 was prepared by the same procedure as syn-
thesis of compound 5 using 4 and n-hexylamine in 96%
yield as a white solid (The purity checked by GC was 99%).
ꢀ
1
Mp. 39.5–40.5 C. H NMR (CDCl ): d(ppm) 0.90 (t, J ¼ 7.0
3
3 2
Hz, ACH , 3H), 1.29–1.37 (m, ACH A,6H), 1.62–1.68 (m,
ACH A, 2H), 3.59 (dt, J ¼ 7.0 and 1.2 Hz, ¼¼ NCH A, 2H),
2
2
7
.34 (s, thiophene proton, 1H), 7.98 (t, J ¼ 1.2 Hz,
13
ACH ¼¼ NA, 1H);
C NMR (CDCl ): d(ppm) 14.08, 22.60,
3
PREPARATION AND PROPERTIES OF A NOVEL POLYTHIOPHENE, LEE ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
SCHEME 1 Synthesis of monomers 5 and 6.
0
1
formation of the hydrolyzed product A by GC and H NMR
see Figs. S1 and S2 in the Supporting Information).
SCHEME 3 Preparation of P3HITs.
(
The GRIM polymerization of 5 was performed in the pres-
ence of NiCl (dppp) as a catalyst (Scheme 3). Under the
signals to indicate its high HT-diad selectivity, whereas that
of LR-P3HIT shows signals having shoulders to clarify the
deteriorated regularity by the formation of HH diad (Fig. 1).
The HT contents of LR- and HR-P3HIT estimated by using
2
same conditions described above, 5 was converted to a
regioisomeic mixture of the corresponding Grignard reagents,
to which the nickel catalyst was added. After the solution
was refluxed for 20 h, the resulting polymer was separated
as methanol-insoluble fractions and was purified by column
chromatography packed with triethylamine-treated silica gel
to remove metal catalyst. The GRIM polymerization of 6 and
the purification of the resulting polymer were also con-
ducted under the same conditions. The polymers obtained
from 5 and 6 afforded a low regioregular P3HIT (LR-P3HIT;
Mw ¼ 19,200, M /M ¼ 2.3) and a high regioregular P3HIT
the signals of ACH
b
¼¼ NA were 70 and 95%, respectively.
Optical Properties of P3HITs
Optical properties of P3HITs in THF and chloroform solu-
tions were investigated by UV–vis spectroscopy. In general,
UV–vis spectra of p-conjugated polymers depend on solvent,
where those measured in poor solvents exhibit red shifts
from those measured in good solvents due to their aggrega-
1
2
tion. UV–vis spectra of P3HITs also exhibited a strongly de-
pendence on solvent. However, in contrast to the generality,
the spectra of P3HIT measured in a poor solvent (THF)
exhibited ‘‘blue shift’’ from those measured in chloroform.
The absorption maxima of LR-P3HIT in THF and chloroform
appeared at 410 and 423 nm, respectively, whereas those of
HR-P3HIT in THF and chloroform appeared at 393 and 425
nm, respectively (see Fig. S3 in the Supporting Information).
This finding can be attributable to a polymer folding and for-
mation of an intramolecular aggregate in THF due to a rigid
w
n
(
(
HR-P3HIT; Mw ¼ 25,100, M /M ¼ 2.3), respectively
w
n
Scheme 3). The polydispersities of resulting P3HITs were
higher those reported for P3HT prepared by GRIM method
9
,11
(
M /M ¼ 1.1–1.5).
In general, the lower polydispersity
w
n
of P3HT can be achieved by quenching the polymerization
with HCl solution, which prevents the formation of P3HT-
P3HT by the disproportionation of the P3HT-Ni(II)-Br com-
plex. However, this method cannot be used in our system,
because the imine group can be decomposed easily.
1
2b
imine substituent in the side chain.
The introduction of an
The IR spectra of the resulting polymers showed a strong
electron withdrawing imino group to PT was expected to
cause a red shift of absorption maximum. However, the
absorption maximum of P3HIT appeared at a shorter wave-
length compared with that of P3HT (ca. 550 nm). This fact
implied that the introduction of the rigid imino group at the
ꢂ1
absorption at 1627 cm , which was attributable to C ¼¼ N
1
13
stretching. In the H and C NMR spectra, the signals corre-
sponding to proton and carbon of imino groups were
observed at 8.6 and 154 ppm, respectively. These spectro-
scopic results supported that LR- and HR-P3HIT have imino
groups in the side chain, which survived the polymerization
and purification processes.
3-position was unfavorable for maintaining the planarity of
polymer backbone, which is essential for elongation of p-con-
jugated system.
The regioregularity of the resulting polymers was evaluated
by H NMR spectroscopy, which was used for distinguishing
Besides the spectroscopic analyses in solution state, those in
film state were investigated. Spin-casted P3HIT films were
1
head-to-tail (HT) and head-to-head diads of poly(3-alkylthio-
1
1
1
phene). The H NMR spectrum of HR-P3HIT showed sharp
1
FIGURE 1 H NMR spectra of LR- (a) and HR-P3HIT (b) in
SCHEME 2 Reactions of 5 and 6 with i-PrMgCl.
CDCl3.
1192
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
pared from THF solution exhibited kmaxs at shorter wave-
length than those of LR-P3HIT (Table 1). This phenomenon
is not currently explainable clearly. As described above, both
HR- and LR-P3HITs in THF seems to have twist and intramo-
lecularly aggregated structure due to imino groups. We
assume that LR-P3HIT containing more tail-to-tail parts,
which may give relatively planar skeleton in THF due to
weak repulsion by imino groups, afforded more red shift of
absorption maxima than those of HR-P3HIT.
Photofluorescence (PL) spectra of P3HITs were measured in
solution and film states (Table 1). LR-P3HIT in THF and
chloroform exhibited PL kmaxs at 555 and 558 nm, respec-
tively. HR-P3HIT in THF and chloroform showed those at
559 and 558 nm, respectively (see Fig. S4 in the Supporting
Information). It was found that PL spectra of polymers are
not affected significantly by polymer regioregularity and sol-
vent polarity in the solution state. On the other hand, PL
spectra of HR- and LR-P3HITs prepared from THF and chlo-
roform solution were clearly dependant on the regioregular-
ity and solvent polarity. HR- and LR-P3HIT films prepared
from chloroform solution showed PL kmaxs at 618 and 608
nm, respectively, which are red shifted compared with those
films from THF solution (606 and 599 nm for HR- and LR-
P3HIT, respectively; Fig. 3).
FIGURE 2 UV–vis spectra of LR-P3HIT films from THF (b) and
chloroform (c) and HR-P3HIT films from THF (a) and chloro-
form (d). Insert shows the photographs of spin-casted HR-
P3HIT films from THF (A) and chloroform solutions (B).
prepared from the THF and chloroform solutions, and their
UV–vis spectra were investigated. Absorption maxima of the
films of LR-P3HIT prepared from the THF and chloroform
solutions appeared at 416 and 467, respectively (Fig. 2). On
the other hand, those of HR-P3HIT films prepared from the
THF and chloroform solutions appeared at 408 and 487 nm,
respectively (Fig. 2). These wavelengths were longer than
those observed in the solutions. Interestingly, UV–vis spectra
of P3HIT films exhibited a strong dependence on the solvent
used for casting. The drastic red shifts of absorption maxima
of P3HIT films from chloroform are attributed to the inter-
Preparation and Optical Properties of P3TCHO
Preparation of P3TCHO from P3HIT by hydrolysis of the im-
ino group was conducted. P3HIT solution in THF was added
into 1 M HCl aqueous solution, and the solution was stirred
ꢀ
for 30 min at 70 C. The resulting precipitates were collected
by filtration and washed with water and methanol to give
P3TCHO as a black solid in 84% yield. Resulting P3TCHO
was insoluble in THF, chloroform, DMF, DMSO, and so forth.
IR spectrum of P3TCHO shows strong and broad C ¼¼ O
1
2b
molecular aggregation of polymer chains.
On the other
hand, the twist and intramolecularly aggregated structures of
the polymers in THF solution may be retained even in the
film; absorption maximum of the film was slightly shifted
when compared with that in THF solution. The spectrum
pattern of P3HIT films prepared from chloroform solution
significantly depended on the regioregularity. The HR-P3HIT
film exhibited an absorption maximum at longer wavelength
by 20 nm than that of the LR-P3HIT film. However, the films
prepared from THF solution showed a different result;
absorption maximum of HR-P3HIT was blue-shifted by 8 nm
compared with LR-P3HIT film. Despite the fact that HR-
P3HIT has higher regioregularity than LR-P3HIT, UV–vis
spectra of both HR-P3HIT in THF and HR-P3HIT film pre-
ꢂ1
stretching band at 1673 cm (see Fig. S4 in the Supporting
Information). Although the complete disappearance of C ¼¼ N
stretching band was not clear due to the overlap by broad
C ¼¼ O band, a very weak intensity of aliphatic band at 2850–
ꢂ1
2
940 cm indicated disappearance of the imino moieties.
TABLE 1 Optical Properties of P3HITs
UV–Vis kmax (nm)
PL kmax (nm)
a
b
a
b
Solution
Film
Solution
Film
THF CHCl
LR-P3HIT 410 423
HR-P3HIT 393 425
3
THF CHCl
416 467
408 487
3
THF CHCl
555 558
559 558
3
THF CHCl
599 608
606 618
3
FIGURE 3 PL spectra of LR- and HR-P3HIT films from THF and
chloroform solutions. [Color figure can be viewed in the online
issue, which is available at wileyonlinelibrary.com.]
a
ꢂ5
Conc. ¼ 1.0 ꢁ 10 M.
b
Spin casted using THF and chloroform solutions.
PREPARATION AND PROPERTIES OF A NOVEL POLYTHIOPHENE, LEE ET AL.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
P3HITs with low regioregularity and high regioregularity
were obtained, respectively. By hydrolysis of the imino
groups in the side chains under acidic conditions, P3HIT was
successfully converted into the correspoding PT (P3TCHO)
having aldehyde groups. This transformation was also per-
formed facilely by exposing the P3HIT film to HCl gas to give
the PT having aldehyde moiety. The reverse way from alde-
hyde to imine was also successfully demonstrated.
REFERENCES AND NOTES
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(a) Zaumseil, J.; Sirringhaus, H. Chem Rev 2007, 107,
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FIGURE 4 UV–vis spectra and a photo (insert) of an as-pre-
pared P3HIT film [solid line, (a)], a film [dashed line, (b)]
obtained after exposed to HCl vapor and a film [dotted line,
2
(a) Brabec, C. J.; Winder, C.; Sariciftci, N. S.; Hummelen, J.
(
3
c)] after Et N teatment of HCl-exposed film. [Color figure can
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be viewed in the online issue, which is available at
wileyonlinelibrary.com.]
We also succeeded in the facile preparation of a P3TCHO film
from the P3HIT film by treatment with HCl gas in the presence
of moisture (Scheme 4). The film of HR-P3HIT prepared from
its chloroform solution by spin-coating was used. As shown in
Figure 3, the film was red with the UV–vis absorption maxi-
mum at 487 nm. A part of the film (two-thirds from the bot-
tom) was exposed to HCl gas vaporized from concentrated hy-
drochloric acid for 30 s. As a result, the color of the film
changed from red to deep violet very quickly, with the signifi-
cant shift of the absorption maximum to 550 nm. This change
was in good accordance with the hydrolysis of the imino moi-
ety into aldehyde, which was confirmed by ATR-IR analysis of
the film (see Fig. S5 in the Supporting Information); the inten-
3
(a) Kim, J. K.; Lee, K.; Coates, N. E.; Moses, D.; Nguyen, T.-Q.;
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ꢂ1
sity of the IR absorption due to the imino group at 1627 cm
was decreased, whereas the absorption due to the aldehyde
moiety at 1673 cm appeared clearly. Another interesting fea-
6
Brembilla, A.; Collard, A.; Henry, B.; Jadamiec, M.; Lapkow-
ꢂ1
ski, M.; Matlengiewicz, M.; Rodeh u¨ ser, L. Phosphorous Sulfur
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ture of this system was its reversibility. When a half of the vio-
let area was treated with triethylamine vapor, the red color of
the HR-P3HIT film was recovered. At the same time, the UV–
vis and IR spectra also confirmed the recovery of P3HIT hav-
ing imino pendants. Hexylamine hydrochloride, which was
formed by the hydrolysis of the imino group and remained in
the film, would be the source of hexylamine for the recovery
of the imino group.
7
(a) Radhakrishnan, S.; Subramanian, V.; Somanathan, N. Org
Electron 2004, 5, 227–235; (b) Radhakrishnan, S.; Somanathan,
N. J Mater Chem 2006, 16, 2990–3000.
8
(a) Si, P.; Mortensen, J.; Komolov, A.; Denborg, J.; Møller, P.
J. Ana Chim Acta 2007, 597, 223–230; (b) Pande, R.; Kamtekar,
S.; Ayyagari, M. S.; Kamath, M.; Marx, K. A.; Kumar, J.; Tripa-
thy, S. K.; Kaplan, D. L. Bioconjug Chem 1996, 7, 159–164.
9
(a) Loewe, R. S.; Ewbank, P. C.; Liu, J.; Zhai, L.; McCullough,
CONCLUSIONS
R. D. Macromolecules 2001, 34, 4324–4333; (b) Iovu, M. C.;
Sheina, E. E.; Gil, R. R.; McCullough, R. D. Macromolecules
P3HIT was synthesized by GRIM method. By the polymeriza-
tions of the 2,5-dibromothiophene-type monomer 5 and the
2
005, 38, 8649–8656; (c) Miyakoshi, R.; Yokoyama, A.; Yoko-
5-bromo-2-iodothiophene-type monomr 6, the corresponding
zawa, T. J Am Chem Soc 2005, 127, 17542–17547.
1
0 Gallazzi, M. C.; Toscano, F.; Paganuzzi, D.; Bertarelli, C.; Fa-
rina, A.; Zotti, G. Macromol Chem Phys 2001, 202, 2074–2085.
1
1 Chen, T.-A.; Wu, X.; Rieke, R. D. J Am Chem Soc 1995, 117,
2
33–244.
1
2 (a) Lanzi, M.; Della-Casa, C.; Costa-Bizzarri, P.; Bertinelli, F.
Macromol Chem Phys 2001, 202, 1917–1923; (b) Shibaev, P. V.;
Schaumburg, K.; Bjornholm, T.; Norgaard, K. Synth Met 1998,
97, 97–104.
SCHEME 4 Reversible preparation of P3HIT and P3TCHO films.
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