Synthesis of copper phthalocyanine-containing hyperbranched polymer starting from 1,2-Bis(3,4-dicyanophenoxy)benzene and CuCl

Article abstract of DOI:10.1246/cl.2006.1306

A novel soluble hyperbranched polymer with copper phthalocyanine (CuPc) was successfully prepared by copper fusion technique of 1,2-bis(3,4-dicyanophenoxy) benzene and CuCl. The structure of copper phthalocyanine-containing hyperbranched polymer confirmed

Full text of DOI:10.1246/cl.2006.1306

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Chemistry Letters Vol.35, No.11 (2006)
Synthesis of Copper Phthalocyanine-containing Hyperbranched Polymer
Starting from 1,2-Bis(3,4-dicyanophenoxy)benzene and CuCl
ꢀ
Young Kwon, Teruaki Hayakawa, and Masa-aki Kakimoto
Department of Organic & Polymeric Materials, Tokyo Institute of Technology,
2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552
(Received July 18, 2006; CL-060810; E-mail: mkakimot@o.cc.titech.ac.jp)
ꢁ
1
1
A novel soluble hyperbranched polymer with copper
1542, 1392 cm assignable to the –NO2 of 4-nitrophthalonitrile
and 3400 cm assignable to –OH of catechol. Melting point
ꢁ
phthalocyanine (CuPc) was successfully prepared by copper
fusion technique of 1,2-bis(3,4-dicyanophenoxy)benzene and
CuCl. The structure of copper phthalocyanine-containing hyper-
branched polymer confirmed by IR, UV–vis absorption spectra.
This polymer showed good solubility in DMF, DMAc, and high
thermal stability.
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ꢂ
16
was 191 C (measured by DSC, lit. 188–189 C).
Copper phthalocyanine-containing hyperbranched polymer
2
,3
(1) was prepared by copper fusion technique as follows
1
7
(Scheme 1). Structure of 1 was identified by IR, UV–vis
absorption spectra. The IR spectrum of 1 showed characteristic
ꢁ
1
absorptions corresponding to the 1771, 746 cm
of CuPc
ꢁ
1
18
and 2231 cm of –CN. At the result of solubility test, 1 was
soluble in DMF, DMAc while CuPc itself was not soluble in
these solvents. The UV–vis absorption spectra of 1 has peak at
611 and 678 nm which was the same as derivative CuPc peak8
(Figure 1). It means that CuPc is successfully introduced in
hyperbranched polymer chains.
Phthalocyanines (Pc) have become one of the most exten-
sively studied classes of materials owing to their unique struc-
ture, their extremely high thermal stability, and their potential
1
for commercial exploitation. Copper phthalocyanine (CuPc) is
widely used as an hole-transport layer (HTL) and buffer layer
in organic light-emitting diodes (OLEDs). One method of some
commercial significance for the manufacture of CuPc involves
the reaction of phthalonitrile (benzene-1,2-dicarbonitrile) with
copper metal or a copper salt at elevated temperatures either in
the melt phase or in high boiling solvents. This phthalonitrile
The result of gel permeation chromatography (GPC) meas-
urement of 1 showed that weight-average molecular weight
3
(M ) was 12:8 ꢃ 10 , and M =M was 1.37 with detector
w
w
n
(Refractive Index) against PS standard. The thermal properties
of 1 was examined by thermogravimetry analysis (TGA). It
showed excellent thermal stability, the 10% weight loss was at
2
,3
route to CuPc reported initially by Linstead and co-workers,
4
,5
ꢂ
has been the subject of a number of investigations, and
attempts have been made to explain the reaction sequence by
which the phthalocyanine system is constructed from individual
371 C (Figure 2).
Contents of CuPc unit in 1 was calculated based on the fol-
lowing observation. Quantitative analysis is based on the appli-
cation of the BEER-LAMBERT LAW, which is given by
6
phthalonitrile units. But most CuPc derivatives are used as
vapor-deposited thin films, or composite materials dispersed
in polymer binder, because of their insufficient solubility in or-
ganic solvents. The solubility or processability of the CuPc could
be improved by introduction of the flexible units such as phenyl
CN
O
O
CN
CN
CuCl
7
–9
Copper phthalocyanine
containing hyperbranched polymer
alkyl groups or ether linkages at exterior of CuPc ring system.
Hyperbranched polymers have received much attention in recent
years, because of their unique architecture. These polymers
show attractive properties such as low viscosity and excellent
DMAc
CN
1
0–12
solubility in organic solvents,
and prepared by one-step
Scheme 1. Synthesis of copper phthalocyanine-containing
hyperbranched polymer.
polymerization of ABx monomers, thus seem to be suitable for
large scale production. As compared to their linear analogues,
various functional groups can be introduced into their structures
1
1
3
to create new functional polymeric materials. In this paper, we
report the synthesis of a novel soluble copper phthalocyanine
containing hyperbranched polymer starting from 1,2-bis(3,4-di-
cyanophenoxy)benzene and CuCl. The monomer was designed
to enhance the solubility of corresponding polymers by not only
introduction of flexible ether units in the backbone but also intro-
ductions of ortho disubstituted structure. As shown in Ref. 14,
catechol and 4-nitrophthalonitrile were allowed to react through
nucleophilic substitution in the presence of potassium carbonate
to give 1,2-bis(3,4-dicyanophenoxy)benzene in 64% yield. The
0
0
0
0
0
0
0
0
0
.9
.8
.7
.6
.5
.4
.3
.2
.1
0
1
5
500
550
600
650
nm
700
750
800
structure was assigned on the basis of NMR, IR spectra. All
of the peaks in the NMR spectra were well-assigned to estimated
structure. The IR spectrum showed characteristic absorptions
Figure 1. UV–vis absorption spectra of copper phthalocyanine-
containing hyperbranched polymer.
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1
corresponding to the 2230 cm of –CN and no bands at around
Copyright Ó 2006 The Chemical Society of Japan

Chemistry Letters Vol.35, No.11 (2006)
1307
1
00
thermal stability and good solubility in DMF, DMAc. This poly-
mer is expected as good solution processable materials for hole-
transport materials and buffer layers in OLEDs as well as other
microelectronics fields.
8
6
4
2
0
0
0
0
0
References and Notes
1
R. M. Christie, D. D. Deans, J. Chem. Soc., Perkin Trans II,
989, 193.
1
2
3
4
5
R. P. Linstead, A. R. Lowe, J. Chem. Soc. 1934, 1022.
C. E. Dent, R. P. Linstead, J. Chem. Soc. 1934, 1027.
M. T. Reetz, N. Jiao, Angew. Chem. 2006, 118, 2476.
H. Z. Lecher, H. T. Lacey, H. P. Orem, J. Am. Chem. Soc.
0
100
200
300
400
500
Temperature/°C
1
941, 63, 1326.
Figure 2. TGA spectrum of copper phthalocyanine-containing
hyperbranched polymer in air.
6
F. Baumann, B. Bienert, G. R o¨ sch, H. Vollmann, W. Wolf,
Angew. Chem. 1956, 68, 133.
7
8
N. B. McKeown, Adv. Mater. 1999, 11, 67.
J. J. Burack, J. D. LeGrange, J. L. Markham, W. Rockward,
Langmuir 1992, 8, 613.
G. J. Clarkson, N. B. Mckeown, K. E. Treacher, J. Chem.
Soc., Perkin Trans. 1 1995, 1817.
8
7
y = 36x
6
9
1
1
5
4
3
2
1
0
0 C. S. Hong, M. Jikei, R. Kikuchi, M. Kakimoto, Macromo-
lecules 2003, 36, 3174.
1 Y. H. Kim, J. Polym. Sci., Part A: Polym. Chem. 1998, 36,
1
685.
12 G. Yang, M. Jikei, M. Kakimoto, Macromolecules 1999, 32,
215.
2
0
0.05
0.1
0.15
0.2
0.25
13 K. Yamanaka, M. Jikei, M. Kakimoto, Macromolecules
2000, 33, 1111.
g/L
1
4 J. Hao, M. Jikei, M. Kakimoto, Macromolecules 2002, 35,
372.
Figure 3. a of copper phthalocyanine-containing hyper-
branched polymer.
5
1
1
5
H NMR (DMSO-d6, ppm) 8.02 (dd, 2H, J ¼ 9 Hz, J ¼
0
(
:9 Hz), 7.75 (dd, 2H, J ¼ 2:7 Hz, J ¼ 0:9 Hz), 7.47–7.40
A ¼ acl
ð1Þ
1
3
m, 4H), 7.37–7.33 (m, 2H). C NMR (DMSO-d6, ppm)
ꢁ
1
ꢁ1
where A is absorbance, a is absorption coefficient (L g cm ),
c is the concentration of the solute (g/L), l is the path length of
the sample (cm).
1
1
2
1
7
60.1, 144.6, 136.1, 127.8, 123.3, 121.8, 121.5, 116.6,
ꢁ1
15.8, 115.2, 108.6. IR (KBr, cm ): 3433, 3082, 2923,
852, 2360, 2239, 2230, 1587, 1566, 1486, 1455, 1416,
384, 1286, 1257, 1244, 1180, 1103, 951, 901, 873, 852,
95, 775, 669, 525.
If the monomer ideally reacted with CuCl, the structure of
the repeating unit is shown as below (CuPc unit). a value of
CuPc unit in this structure was calculated as a ¼ 205 using
1
6 S.-H. Hsiao, C.-P. Yang, K.-Y. Chu, Macromolecules 1997,
0, 165.
1
9
molecular weight of CuPc unit and CuPc a (281 at 678 nm ).
Hyperbranched polymer a obtained in this study was found
as a ¼ 36 at 678 nm (Figure 3). CuPc unit contents in hyper-
branched polymer calculated using the equation bellow.
We have approximated disassociated CuPc at about 17%, in
all about 20% or more of CuPc is contained in the hyperbranched
polymer.
3
1
7 1.08 g (3 mmol) of 1,2-bis(3,4-dicyanophenoxy)benzene
and 0.09 g (1 mmol) of CuCl were dissolved in 40 mL of
dimethylacetamide (DMAc) and then the mixture was stirred
ꢂ
at 160 C for 24 h. The reaction mixture was poured into
00 mL of water. The crude product was collected by filtra-
8
tion, washed with water, and dried in vacuo. After refluxing
in methanol twice, the product was filtrated and washed
using cold methanol for three times. The dark blue powdery
product was dried in vacuo, affording 0.98 g of copper
phthalocyanine-containing hyperbranched polymer.
O
O
CuPc unit contents
in hyperbranched
polymer /%
N
N
N
N
Hyperbranched polymer a
CuPc unit a
N
Cu
N
N
=
× 100
N
O
O
(
2)
ꢁ1
CuPc unit
1
8 IR (KBr, cm ): 3222, 3065, 2231, 1771, 1717, 1607, 1588,
1565, 1489, 1454, 1402, 1361, 1309, 1255, 1217, 1183,
1092, 1049, 950, 881, 838, 770, 746, 674, 643, 553, 524.
In conclusions, copper phthalocyanine-containing hyper-
branched polymer was synthesized starting from 1,2-bis(3,4-
dicyanophenoxy)benzene and CuCl. This polymer showed high
19 M. Whalley, J. Chem. Soc. 1961, 866.
Published on the web (Advance View) October 25, 2006; doi:10.1246/cl.2006.1306