New approach to Poly(2,7-carbazoles)

Full text of DOI:10.1134/S1070363211120176

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 12, pp. 2517–2519. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © I.A. Dorofeev, V.I. Smirnov, I.A. Tokareva, L.G. Shagun, M.G. Voronkov, 2011, published in Zhurnal Obshchei Khimii, 2011,
Vol. 81, No. 12, pp. 2064–2066.
LETTERS
TO THE EDITOR
New Approach to Poly(2,7-carbazoles)
I. A. Dorofeev, V. I. Smirnov, I. A. Tokareva, L. G. Shagun, and M. G. Voronkov
Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
е-mail: sv_basenko@irioch.irk.ru
Received March 17, 2011
DOI: 10.1134/S1070363211120176
Polycarbazoles and heteropolymers containing car-
bazole fragments possess unique electric and photo-
electric properties. They are used as sensors, light-
emitting diodes, transistors, and photogalvanic elements
We have developed a new method for the synthesis
of poly(2,7-carbazoles) based on thermal polymeriza-
tion (220–270°С) of the first prepared α-iodo-
acetylcarbazoles (I, II) in an argon atmosphere in the
absence of catalyst and solvent.
[1–9]. Special interest to poly(2,7-, 3,6-, and 1,8-
carbazoles) and their copolymers is due to their ability
to fluorescence in the blue region of the spectrum [10].
When heating 1-(9Н-carbazol-9-yl)-2-iodo-1-ethanone
General methods for the synthesis of poly-
carbazoles are based on the reactions of chemical and
electrochemical oxidation of carbazole [10] and its
dihalogenated derivatives [11–15], on Yamamoto
(
I) to 220°С carbon monoxide, ethylene, hydrogen
iodide are evolved, and polycarbazole III with Mw
400, M 1000, М /М (degree of polydispersity) 1.4 is
1
n
w
n
formed in 65% yield. Compound III is soluble in
[16, 17], Suzuki [18], Stille [19], Heck coupling
reactions [20].
organic solvents.
n
o
2
20 C
N
−n(CO, C H , HI)
N
N
H
n
N
2
4
H
H
I
O
I
III
IR spectroscopic study has shown that the centers
of polymerization, most probably, are the 2,7-positions
of the carbazole ring due to the presumed elimination
of hydrogen atoms by the formed iodine radical. This
is confirmed by the presence of absorption bands of the
NMR at 8.46 ppm prove the above structure [23].
We have also studied the possibility of the forma-
tion of poly(2,7-carbazoles) by thermal polymerization
of 1-(9Н-carbazol-2-yl)-2-iodo-1-ethanone (II). The
reaction proceeds at 270°С and leads to the formation
of two modifications of polycarbazole: soluble in
–1
out-of-plane bending vibrations δCH (723, 748 cm )
typical for 3,6-unsubstituted carbon atoms of the
carbazole fragment [21, 22]. The appearance of the ν
acetone IV (M
21.4%) and soluble in THF, DMSO, DMF (V) (M
w n w n
1600, M 1100, М /М 1.4, yield
NH
–
1
absorption band at 3389 cm in the IR spectrum of
w
1
oligomer III [21], and the NH proton signal in the H
1700, M
n
940, М
w
/М
n
1.7, yield 53.57%).
o
n
270 C
I
−
n(CO, C H , HI)
2
4
N
N
H
N
N
O
n
H
H
H
II
IV, V
2
517

2
518
DOROFEEV et al.
NMR, IR, and UV spectra of polymers synthesized
formed was thoroughly washed with ether, dried in a
by thermal polymerization of iodoketones I and II are
vacuum. Yield of compound (III) 1.1 g (65% to
fully identical.
С
72
Н
44
N
6
I
3
), dark lilac powder, decomp. above 450°С.
1
Н NMR spectrum (acetone-d ), δ, ppm: 7.14–8.10
6
In the process of thermal polymerization of
iodoketones I, II, polycarbazoles III–V are doped with
iodine. This is confirmed by the presence of the
absorption bands in the UV spectra at 293 and 358 nm,
characteristic for the I ion [24, 25]. The absence of the
1
3
(
Ar), 8.46 (NH). C NMR spectrum (acetone-d ), δ ,
6 С
–
1
ppm: 142.20–107.80 (Ar). IR spectrum (film), ν, cm :
389 (NH). Found, %: С 63.18; Н 3.47; N 5.36; I
27.92. С Н N I . Calculated, %: C 62.88; Н 3.20; N
3
–
3
7
2
44 6 3
6
.11; I 27.72.
covalently bound iodine in the polymer is proved by
easy removal of the I ion upon reprecipitation of
–
3
Polymerization of 1-(9Н-carbazol-2-yl)-2-iodo-1-
polycarbazole III dissolved in DMSO into water.
ethanone (II). 1-(9Н-Carbazol-9-yl)-2-iodo-1-ethanone
II), 0.5 g (1.5 mmol), was heated in an argon
(
Polycarbazoles III–V are black powders decom-
posed at >450°С. When coated from solution onto
quartz, glass, or metal they form dark lilac films of
high adhesion. The electroconductivity of poly-
atmosphere at 270°С during 3 min, extracted with
acetone (15 ml), and precipitated with hexane (30 ml)
to obtain 0.06 g (21%) of compound IV as a dark lilac
1
–
10
–1
powder decomp. above 450°С. Н NMR spectrum
carbazole (III) is 3.1×10 S cm .
-(9Н-Carbazol-9-yl)-2-iodo-1-ethanone (I). To
the solution in 150 ml of acetone of 3 g (1.2 mmol) of
-(9Н-carbazol-9-yl)-2-chloro-1-ethanone prepared as
1
3
(
acetone-d ), δ, ppm: 7.35–8.16 (Ar), 8.19 (NH).
C
6
1
NMR spectrum (acetone-d ), δ , ppm: 141.88–105.28
6
С
–1
(
%
Ar). IR spectrum (film), ν, cm : 3423 (NH). Found,
: С 65.21; Н 3.41; N 5.79; I 25.92. С Н N I .
1
8
4
51 7 3
described in [26] the solution of 2.16 g (1.4 mmol) of
sodium iodide was added and stirred for 5 h. Yield
Calculated, %: C 65.62; Н 3.19; N 6.38; I 24.80.
Polycarbazole V soluble in THF, DMSO, DMF,
3
.9 g (95%), mp 116–117°С (chloroform). IR spec-
–
1
1
0
.15 g (53.57%), black glittering powder decomp.
trum, ν, cm : 1677 (С=О), 484 (СН I). Н NMR
2
above 450°С. Found, %: С 66.55; Н 3.17; N 5.98; I
spectrum (CDCl ), δ, ppm: 4.38 s (2Н, СН I), 7.18–
3
2
1
3
2
6
2.56. С Н N I . Calculated, %: C 67.42; Н 3.30; N
.58; I 22.39.
8
1
.05 m (Ar). C NMR spectrum (CDCl ), δ , ppm:
96 58 8 3
3
С
.69 (С–I), 110.72–138.37 (Ar), 167.29 (С=О). Mass
+
spectrum, m/z (I , %): 335(40) [M ]. М
335.
rel
calc
FT–IR spectra were recorded on a Vertex 70 Ram
1
13
Found, %: С 49.85; Н 2.90; N 4.29; I 38.05.
С Н NOI. Calculated, %: C 50.15; Н 2.98; N 4.18; I
II spectrometer (KBr, film). Н and С NMR spectra
1
4
10
were registered on a Bruker DPX-400 spectrometer
3
7.91.
(
400 and 100 MHz, respectively). The molecular mass
of polycarbazoles III–V was determined on a gel-
1
-(9Н-Carbazol-2-yl)-2-iodo-1-ethanone
(II).
chromatograph Waters, with refractometric detector, at
Prepared similar to I from 3 g (1.2 mmol) of 1-(9Н-
carbazol-2-yl)-2-chloro-1-ethanone (synthesized as
described in [27]) and 2.16 g (1.4 mmol) of sodium
iodide. Yield 3.8 g (92%), mp 189–190°С. Н NMR
spectrum (DMSO-d ), δ, ppm: 4.69 s (2Н, СН I),
о
2
5 С, eluent THF. Specific electroconductivity was
measured by electrometric amplifier VK-16. Purity of
the products was monitored by TLC on Silufol UV-
1
2
54 plates, eluent acetone.
6
2
1
3
7
(
(
4
[
.21–9.15 m (Ar), 11.56 (1Н, NН). C NMR spectrum
DMSO-d ), δ , ppm: 111.41–141.42 (Ar), 193.57
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С
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 12 2011