Synthesis and electrochemical polymerization of 4,7-Di(2-thienyl)indene

Article abstract of DOI:10.1134/S1070427210080227

4,7-Di(2-thienyl)indene was prepared, and its electrochemical behavior was studied. Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S1070427210080227

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 8, pp. 1440−1443. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © G.G. Abashev, V.P. Begishev, A.Yu. Bushueva, V.A. Romanova, E.V. Shklyaeva, 2010, published in Zhurnal Prikladnoi Khimii, 2010,
Vol. 83, No. 8, pp. 1335−1338.
Synthesis and Electrochemical Polymerization
of 4,7-Di(2-thienyl)indene
G. G. Abashev, V. P. Begishev, A. Yu. Bushueva, V. A. Romanova,
and E. V. Shklyaeva
Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, Perm, Russia
Natural Science Institute, Perm State University, Perm, Russia
Received March 10, 2010
Abstract—4,7-Di(2-thienyl)indene was prepared, and its electrochemical behavior was studied.
DOI: 10.1134/S1070427210080227
A novel field of molecular electronics involving
the use of various organic materials, in particular,
conjugated polymers and oligomers, is vigorously
developing now. The diversity of such materials and
the possibility of varying within wide limits their
electrophysical, magnetic, optical, and electrochemical
properties by modifying the structure of the monomers
make these materials in many cases indispensable and
Scheme.
1
440

SYNTHESIS AND ELECTROCHEMICAL POLYMERIZATION OF 4,7-DI(2-THIENYL)INDENE
1441
(a)
(b)
(c)
I, mA
E, mV
E, mV
E, mV
Fig. 1. Cyclovoltammograms of DTI in various solvents. сVI = 10–3 M, glassy carbon, supporting electrolyte Et NClO (0.1 M). (I)
4
4
–1
–1
Current and (Е) potential; the same for Fig. 2. (a) СН СN, V
= 50 mV s ; (b) CH Cl : СН СN = 10 : 1, V
= 50 mV s ; (c)
3
scan
2
2
3
scan
–1
BF · Et O : CH Cl = 3 : 2, V = 100 mV s .
3
2
2
2
scan
preferable over inorganic materials.
,7-Di(2-thienyl)indene synthesized in [1, 2]
contained unsubstituted α-positions of thiophene rings,
which allowed preparation of the conjugated polymer
by both chemical and electrochemical oxidation.
prepared as shown below. 1,4-Di(2-thienyl)butane-
,4-dione V was synthesized either by acylation of
1
4
thiophene in the presence of AlCl [13] or by Stetter’s
3
method [14]:
The possibility of preparing a polymer from 4,7-di(2-
Indene–coumarone resins prepared by polymerization thienyl)indene (DTI) VI was examined by cyclic
of a mixture of the corresponding monomers under the voltammetry. The choice of the solvent was governed
action of AlCl and other Lewis acids are well known by the solubility of the components and by the quality of
3
in industry. Numerous studies concern electrochemical the film obtained. Cyclovoltammograms recorded in the
polymerizationofunsubstitutedindene[3–12],including examined solvents in the course of potential variation are
its copolymerization with styrene [6], methylstyrene shown in Fig. 1. The shape of the cyclovoltammograms
[7], isoprene [8], and methoxystyrene [9]. Preparation depends on the kind of the anode, especially in going to
and properties of conducting polymeric composites of the ITO (indium–tin oxide) electrode (Fig. 2).
polyindene and polypyrrole have been reported [11, 12].
The potentials corresponding to the onset of the first
In this study we examined the electrochemical
oxidation step Е1ох, first peak Е , onset of the second
1
pa
behavior of 4,7-disubstituted indene VI, which was
oxidation step Е2оx, and second peak Е 2 are given in
p a
the table.
I, mA
As can be seen, an increase in the fraction of
dichloromethane in the solvent (from 0 to 90%) leads
to noticeable growth of the potentials of the oxidation
onset and peaks. With a mixture of boron trifluoride
etherate and dichloromethane (BF · Et O : CH Cl =
3
2
2
2
3
: 2) as solvent, the potentials are considerably lower.
ох
This fact allows Е1 to be varied in a fairly wide range
Results of cyclovoltammetric analysis of DTI
Е1ох
Еpa1
Е2ох
mV
Еpa2
E, mV
Solvent
Fig. 2. Cyclovoltammograms of DTI, recorded on different
electrodes. Solvent CH CN, с = 10–3 M, supporting
СН СN
950 1100 1150 1260
1009 1192 1202 1351
3
3
VI
CH Cl : СН СN = 10 : 1
2
2
3
–1
electrolyte Et NClO (0.1 M), V
= 50 mV s . (1) glassy
4
4
scan
BF ·Et O : CH Cl = 3 : 2
700
911 1047 1181
carbon, (2) platinum, and (3) ITO.
3
2
2
2
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 8 2010

1
442
ABASHEV et al.
H, mm
β, %
For the layer with Н = 0.04 mm, we determined the
resistance in the direction parallel to the film surface,
7
ρ(||) = 1.8 × 10 Ω cm, and also the resistance in the
direction perpendicular to the film surface, ρ(┴) = 2 ×
3
1
0 Ω cm.
Thepronouncedanisotropyoftheelectricalproperties
is due to specific features of the polymer growth in the
direction perpendicular to the electrode plane. At a layer
thickness of 0.010 mm, the structure becomes loose,
which can be seen with an electron micrograph of the
surface of a poly-DTI film.
EXPERIMENTAL
Q, μC cm–2
1
The Н NMR spectra were recorded with a Varian
Mercury plus300 spectrometer, internal reference
HMDS. The reaction progress and the product purity
were monitored by TLC (Silufol, Kavalier). The
reaction mixtures were separated, and the target products
purified, on a column packed with silica gel (Lancaster,
Silica gel 60, 0.060–0.2 mm). Cyclic voltammograms
were taken on an IPC-compact potentiostat–galvanostat
(Vol’taProm Limited Liability Company) with an EM-
Fig. 3. Current efficiency β and thickness Н of poly-DTI
layer as a function of the electric charge Q passed through the
electrolyte. Pt, CH Cl : СН4 СN = 10 : 1, Et NClO (0.1 M),
2
2
3
4
4
–2
3
current density j = 0.55 mA cm . с × 10 , M: (1, 2) 5 and
VI
(3) 25.
depending on the medium in which the electrochemical
polymerization is performed.
0
4 electrochemical sensor in a standard three-electrode
The electrochemical polymerization of DTI in the
examined solvents yielded in all the cases a film of
a polymer insoluble in common solvents.
cell with glassy carbon (or ITO) working electrode,
platinum auxiliary electrode (ERL-02), and silver
chloride reference electrode (EVL-1M4) at room
temperature. The surface of the films was examined
with an S-3400N electron microscope (Hitachi).
We studied the redox stability of the poly-DTI film
at cyclic variation of the potential from –1400 to 1400
mV in a pure solvent. The polymer remains stable under
these conditions and is doped in the anodic region with
2-Acetylthiophene was synthesized by acylation
of thiophene with acetic anhydride in the presence of
H PO [15]; 3-dimethylamino-1-(2-thienyl)propanone
–
the counterion [ClO ] (Е = 1150 mV), and in the
4
А
cathodic region, with tetraethylammonium cation (Е =
K
3
4
–
720 mV).
hydrochloride, by the Mannich reaction [14]; and
succinyl chloride, from succinic anhydride [16].
Dimethyl sulfoxide was dried over BaO for 3 days
and then distilled in an inert atmosphere from ВаО.
Cyclopentadiene was prepared immediately before the
reaction by cleavage of commercial dicyclopentadiene
In electrochemical polymerization of DTI in the
galvanostatic mode, because of low solubility of DTI
in acetonitrile and of Et NClO in dichloromethane and
nonpolar solvents, as the best medium for preparing
polymer films we used the mixture CH Cl : СН СN
=
4
4
2
2
3
[17].
10 : 1. Figure 3 shows how the thickness Н of the
deposited polymer film and the current efficiency β
depend on the amount of the electricity consumed Q.
As can be seen, with an increase in the charge passed
through the electrolyte and in the film thickness,
the polymer yield is a function of current decreases,
showing the logarithmic dependence. An increase in the
monomer concentration does not alter the result.
4
,7-Di(2-thiophen-2-yl)indene VI. To 17 ml of
a 30% solution of sodium methylate preliminarily
cooled to 0°С, we added over a period of 1 h a solution
of a mixture of 8.15 g (32.6 mmol) of 1,4-di(2-thienyl)-
1
,4-butanedione and 2.9 ml (35.4 mmol) of freshly
prepared cyclopentadiene in DMSO. In the process, the
temperature was kept in the range from –25 to –10°С.
After adding the whole amount of the reactants, the
mixture was stirred for 2 h, poured into ice-cold water
Figure 3 shows that the thickness of films synthesized
in the course of DTI electropolymerization is limited.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 8 2010

SYNTHESIS AND ELECTROCHEMICAL POLYMERIZATION OF 4,7-DI(2-THIENYL)INDENE
300 ml), and extracted with diethyl ether (or CH Cl ).
3. Bhadani, S.N. and Baranwal, P.P., Makromol. Chem.,
2 2
1443
(
1
977, vol. 178, no. 4, pp. 1049–1060.
The combined organic extracts were dried over calcined
MgSO , the solvent was evaporated, and the residue
4
4. Bhadani, S.N. and Baranwal, P.P., Makromol. Chem.,
977, vol. 178, no. 9, pp. 2637–2647.
was chromatographed on a column (eluent : hexane :
CH Cl = 2 : 1). White crystalline substance, yield 30%,
1
2
2
5
. Akbulut, U., Eren, S., and Toppare, L., J. Macromol. Sci.
Chem. A, 1984, vol. 21, no. 3, pp. 335–342.
1
mp. 75–76°С. H NMR spectrum (CDCl , δ, ppm, J,
3
Hz): 3.68 d (2Н, СН СН=, J 1.8), 6.69 and 6.72 dt (1Н,
2
=
СНСН , J 2.1), 7.12 and 7.16 two t (2Н, 2 thiophene,
6. Toppare, L., Eren, S., and Akbulut, U., British Polym. J.,
2
J 3.6), 7.26 and 7.27 dd (1Н, thiophene, J 3.6), 7.34
and 7.37 m (3Н, thiophene + 2 phenyl), 7.40–7.42
dd (1Н, thiophene, J 3.6), 7.46 and 7.52 d (1Н, СН=,
J 15.0), 7.48 and 7.49 (1Н, thiophene, J 3.3); published
1985, vol. 17, pp. 257–259.
7
. Toppare, L., Eren, S., and Akbulut, U., J. Polym. Sci.,
Polym. Chem., 1984, vol. 22, no. 11, pp. 2941–2944.
data: 3.70 t (CH ), 6.65 dt (CH=), 7.0–7.5 m (phenyl +
8. Khursid, A., Toppare, L., and Akbulut, U., Polym.
Commun., 1987, vol. 28, no. 11, pp. 269–271.
2
thiophene) [1].
9
. Akbulut, U., Khursid, A., Hacıoğlu, B., and Toppare, L.,
Polymer, 1990, vol. 31, no. 7, pp. 1343–1346.
CONCLUSION
1
0. Toppare, L., Handbook of Polymer Science and
Technology, vol. 1: Synthesis and Properties,
Cheremisinoff, N.P., New York: Dekker, 1989, pp. 271–
Films of a conjugated polymer derived from 4,7-di(2-
thienyl)indene were prepared by electrochemical
polymerization on the surface of a working glassy carbon
or indium–tin oxide electrode under various conditions.
The redox stability of the films was evaluated, the
electrical resistivity was measured, and the morphology
was determined.
3
06.
11. Bozkurt, A., Akbulut, U., and Toppare, L., Synth. Met.,
1996, vol. 82, no. 1, pp. 41–46.
1
1
1
1
2. Bozkurt, A., Erçelebi, Ç., and Toppare, L., Synth. Met.,
997, vol. 87, no. 3, pp. 219–223.
1
ACKNOWLEDGMENTS
3. Nakazaki, J., Chung, I., Matsushita, M.M., et al., J. Mater.
Chem., 2003, vol. 13, no. 5, pp. 1011–1022.
The study was financially supported by the
Russian Foundation for Basic Research (project no.
4. Wynberg, J.H. and Metsebaar, J., Synth. Commun., 1984,
1
0-03-96038-r-ural-a) and Analytical Departmental
vol. 14, no. 1, pp. 1–9.
Target Program of the Russian Ministry for Education
and Science “Development of the Scientific Potential of
Higher School.”
5. Hartought, H.D., Hochgessang, F.P., and Blick, F.F.,
Thiophene and Its Derivatives. Appendix: Laboratory
Preparation of Thiophene Compounds, New York:
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