Discotic liquid crystals of transition metal complexes 46: Mesomorphism and antagonist solubility of octaphenoxyphthalocyaninato copper(II) complex substituted by oligoether chains

Article abstract of DOI:10.1142/S1088424612501222

We synthesized a novel discotic liquid crystalline compound, octakis[3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)phenoxy]phthalocyaninato copper(II) (abbreviated as [m-MeO(EtO)₃PhO]₈PcCu), and established the mesomorphism by using a diffe

Full text of DOI:10.1142/S1088424612501222

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2012; 16: 1209–1216
DOI: 10.1142/S1088424612501222
Published at http://www.worldscinet.com/jpp/
Discotic liquid crystals of transition metal complexes 46†:
mesomorphism and antagonist solubility of octaphenoxy-
phthalocyaninato copper(II) complex substituted by
oligoether chains
Hiroyuki Satoa, Yuya Sakagamia, Eiji Itohb and Kazuchika Ohta*a◊
a Smart Material Science and Technology, Department of Bioscience and Textile Technology, Interdisciplinary
Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda 386-8567, Japan
b Department of Electrical and Electronic Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553,
Japan
Received 13 May 2012
Accepted 23 June 2012
ABSTRACT: We synthesized a novel discotic liquid crystalline compound, octakis[3-(2-(2-(2-
methoxyethoxy)ethoxy)ethoxy)phenoxy]phthalocyaninato copper(II) (abbreviated as [m-MeO-
(EtO)3PhO]8PcCu), and established the mesomorphism by using a differential scanning calorimeter, a
polarizing optical microscope, and temperature-dependent wide angle X-ray diffraction diffractometer.
Very interestingly, this [m-MeO(EtO)3PhO]8PcCu complex showed a hexagonal ordered columnar
(Colho) mesophase in the virgin sample, whereas it showed a rectangular ordered columnar (Colro(P21/a))
mesophase in the non-virgin sample. The Colho mesophase gave a dimer stacking distance at 9.26 Å,
whereas the Colro mesophase gave a short monomer stacking distance at 3.45 Å. Furthermore, this novel
Pc derivative is readily soluble in polar solvents such as acetone, ethanol and methanol. Using antagonist
solubilities of the present hydrophilic [m-MeO(EtO)3PhO]8PcCu derivative in a polar solvent and the
previous hydrophobic (C10O)16TzCu derivative in the non-polar solvent, a p-n junction layered thin films
could be successfully prepared.
KEYWORDS: discotic liquid crystal, antagonist solubility, phthalocyanine, columnar mesophase, p-n
junction.
Discotic liquid crystals form columnar mesophases by
INTRODUCTION
piling up the aromatic core parts by the p-p interactions.
Discotic liquid crystals have been investigated as self-
The one-dimensional columnar structures can allow fast
organized soft materials. They generally consist of an
charge carrier transportation along the columns [5–7].
aromatic core surrounded by several long chains to show
Hence, we have been focused our interests on discotic
mesomorphism [1, 2]. Many discotic liquid crystals have
liquid crystalline semiconductors and their applications
been synthesized for different core systems. Especially,
to solar cells [8, 9], electroluminescent displays [10,
triphenylene-based derivatives [3] and phthalocyanine-
11], and field effect transistors [12, 13]. Performance of
based ones [4] have been studied intensively to date.
such electronic devices may be largely influenced by the
stacking distance in the columnar mesophases [16, 17].
SPP full member in good standing
Currently, organic thin films for solar cells are formed
by vacuum deposition method [18, 19]. This is due to low
solubilities of the conventional organic semiconductors
in organic solvents, which limit the film formation
methods. If liquid crystalline semiconductors would be
*Correspondence to: Kazuchika Ohta, tel: +81 268-21-5492,
email: ko52517@shinshu-u.ac.jp
†Part 45: Sato H, Igarashi K, Yama Y, Ichihara M, Itoh E and
Ohta K. J. Porphyrins Phthalocyanines 2012; 16: 1148–1158.
Copyright © 2012 World Scientific Publishing Company

1210 H. SATO ET AL.
employed, the solubilities would be greatly improved
and the film formation could be achieved, for example by
spin coating. These film formation methods enable us to
reduce the cost and easily form large area of thin films.
Moreover, when discotic liquid crystalline donor (p-type)
and acceptor (n-type) semiconductors are employed,
they spontaneously form a one-dimensional columnar
structure, which forms an excellent pathway for hole
and electron transport. Generally, when liquid crystalline
compounds are substituted by hydrophobic alkyl and
alkoxy groups, they become readily soluble in non-polar
solvents. On the other hand, when liquid crystalline
compounds are substituted by hydrophilic oligoether
and hydroxy groups, they become to be readily soluble
in polar solvents, instead. Therefore, these two types
of liquid crystalline compounds can show antagonist
solubilities. Antagonist solubility means that one
compound is soluble in a solvent but another compound
is insoluble in the same solvent. Antagonist solubility can
make the device fabrication very easy [20]. When both
n-type and p-type of liquid crystalline semiconductors
could be given such antagonist solubilities, the p-n
junction of two layered thin films could be easily prepared
by spin coating, casting and so on.
having a very short stacking distance 3.33 Å. Such a short
stacking distance may afford very fast carrier mobility.
Since this (m-C12OPhO)8PcCu (3) derivative is substituted
by the hydrophobic alkoxy groups, it is insoluble in polar
solvent such as acetone, ethanol and so on. Accordingly,
in this work we have synthesized a novel phthalocyanine
derivative substituted by hydrophilic oligoether groups,
2,3,9,10,16,17,23,24-octakis[3-(2-(2-(2-methoxyethoxy)
ethoxy)ethoxy)phenoxy]phthalocyaninato
copper(II)
(abbreviatedas[m-MeO(EtO)3PhO]8PcCu:4).Weexpected
this new Pc derivative would give a single columnar
mesophase having a very short stacking distance and good
solubility in polar solvents. If successful, the obtained
hydrophilic p-type liquid crystalline [m-MeO(EtO)3PhO]
(4) derivative will be able to form a thin film on a thin
film of the previously synthesized hydrophobic n-type
liquid crystalline derivative, tetrakis(2,3,6,7-tetraalkoxy)-
1,4-diazatriphenylenocyaninato copper(II) (abbreviated
as (CnO)16TzCu: 5) [23], and prepare a p-n junction of the
layered films by using their antagonist solubilities.
We wish to report here the synthesis and interesting
properties of the novel [m-MeO(EtO)3PhO]8PcCu (4)
derivative. The formation of a double layer film of 4 and
5 is also described.
We have investigated many columnar liquid crystals
based on phthalocyanine to date. Among them, we
found very fast carrier mobilities, 0.28 cm2/Vs for
2,3,9,10,16,17,23,24-oct-akis(alkylthio)phthalocyanine
(abbreviated as (C12S)8PcH2: 1) [21], and 0.71 cm2/Vs
for bis[2,3,9,10,16,17,23,24-octakis(alkylthio)phthalocyani-
nato]lutetium(III)(abbreviatedas[(C12S)8Pc]2Lu:2)[17].We
also synthesized 2,3,9,10,16,17,23,24-octakis(3-dodecyl-
oxyphenoxy)phthalocyaninato copper(II) (abbreviated as
(m-C12OPhO)8PcCu: 3) as a p-type of liquid crystalline
semiconductor [22]. It shows a single columnar mesophase
EXPERIMENTAL
Synthesis
Scheme 1 shows the synthetic route for the phthalocy-
anine copper complex ([m-MeO(EtO)3PhO]8PcCu (4)).
The starting materials of triethylene glycol monomethyl
ether and p-toluenesulfonyl chloride (TsCl) were purchased
from Tokyo Chemical Industry (Tokyo Kasei) and
OH
TsCl
resorcinol
ROH
ROTs
R =
O
O
O
NaOH/THF/H2O
K2CO3/MeCN
6
OR
7
RO
OR
NC
O
CN
O
O
O
NC
NC
Cl
Cl
OR
OR
OR
OR
N
N
N
CuCl2
1-pentanol, DBU
O
O
O
O
Cu N
N
K2CO3/DMA
N
N
N
RO
OR
8
O
O
RO
OR
4
Scheme 1. Synthetic route for [m-MeO(EtO)3PhO]8PcCu (4). DMA = N, N′-dimethylacetamide and DBU = 1,
8-diazabicyclo[5, 4, 0]-7-undecene and TsCl = p-toluenesulfonyl chloride and THF = tetrahydrofuran
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1210–1216

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 46 1211
Kanto Chemical Co., Inc. (Kanto Kagaku), respectively.
N′-dimethylacetamide (DMA: 22 mL) were poured.
The reaction mixture was heated with stirring at 120 °C
under a nitrogen atmosphere for 2 h. It was extracted
with CH2Cl2 and washed with water. The organic layer
was dried over anhydrous sodium sulfate and evaporated
under reduced pressure. The residue was purified by
column chromatography (silica gel, ethyl acetate, Rf =
0.45). The product was obtained as pale yellow oil (1.31
g). Yield 52%. IR (KBr, cm-1): 2924, 2875 (-CH2-), 2814
Ether derivative 6 was synthesized from triethylene
glycol monomethyl ether and TsCl by the method of
Percec et al. [24]. Phenol derivative 7 was synthesized
from commercially available resorcinol (Wako Pure
Chemical Industry: Wako) and the ether derivative 6
by the method of Dennis et al. [25]. Dicyano derivative
8 was synthesized from commercially available 4,
5-dichlorophthalonitrile (Tokyo Kasei) and the ether
derivative 6 by our previously reported method [22]. The
target phthalocyanine derivative 4 was synthesized from
the dicyano derivative 8. The detailed procedures are
described as follows.
1
(-OCH3), 2232 (-CN). H NMR (CDCl3, TMS): d, ppm
3.38 (6H, s, O-CH3), 3.54–3.56 (4H, m, O-CH2-CH2-O),
3.64–3.75 (12H, m, O-CH2-CH2-O), 3.87 (4H, t, J = 4.9
Hz, PhOCH2-CH2), 4.11–4.15 (4H, m, PhO-CH2), 6.64–
6.65 (4H, m, Ph-H), 6.80–6.85 (2H, m, Ph-H), 7.20 (2H,
s, Ph-H), 7.33 (2H, t, J = 8.6 Hz, Ph-H).
2-[2-(2-methoxyethoxy)ethoxy]ethoxy-1-(4-methy-
lbenzenesulfonate) (6). Into a 100 mL of three-necked
flask, triethylene glycol monomethyl ether (5.42 g, 33.0
mmol), NaOH (2.0 g), tetrahydrofuran (THF) (30 mL)
and water (5 mL) were poured. The flask was immersed
in an ice-water bath. To this solution, a solution of
TsCl (5.25 g, 27.5 mmol) in 7.5 mL of THF was added
dropwise with keeping temperature of the reaction
mixture < 5 °C. After complete addition, the reaction
mixture was stirred at 0 °C for 2 h. After neutralization
with 10% HCl aqueous solution, it was extracted with
CH2Cl2. The organic layer was dried over anhydrous
sodium sulfate, evaporated under reduced pressure and
dried under vacuum to give 8.51 g of transparent oil.
2,3,9,10,16,17,23,24-octakis[3-(2-(2-(2-methoxye-
thoxy)ethoxy)ethoxy)phenoxy]-
phthalocyaninato
copper (II) (4). Into a 50 mL of three necked flask, 4, 5-bis
[3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]- phenoxy]phtha-
lonitrile (8: 0.400 g, 0.628 mmol), 1-pentanol (4 mL),
CuCl2 (42.2 mg, 0.314 mmol) and 1, 8-diazabicyclo[5, 4,
0]-7-undecene (DBU: 5 drop) were poured. The reaction
mixture was refluxed under a nitrogen atmosphere for
24 h. After complete reaction, it was evaporated under
reduced pressure. The residue was purified by solid-liquid
extraction with hot n-hexane. The remained product
was further purified by column chromatography:
the impurities were eluted with a mixture solvent of
CHCl3:THF = 2:1(v/v) (silica gel, except for Rf = 0)
and the target compound at Rf = 0 was eluted with
THF. The pure product was obtained as a dark green
liquid crystal (0.383 g). Yield 93%. UV-vis (CHCl3;
concentration: 7.66 × 10-6 M): lmax nm (log e) 283.0
(4.91), 341.8 (4.98), 389.2 (4.66), 613.4 (4.72), 649.5
(4.68), 681.3 (5.45). MS (MALDI-TOF): m/z 2609.98
(calcd. 2610.30). Anal. calcd. For C136H160N8: C,
62.33: H, 6.10: N, 4.29%. Found: C, 62.58; H, 6.18:
N, 4.29%.
1
Yield 97%. H NMR (CDCl3, TMS): d, ppm 2.45 (3H,
s, Ph-CH3), 3.37 (3H, s, O-CH3), 3.51–3.70 (10H, m,
O-CH2-CH2-O, SO2OCH2- CH2-O), 4.16 (2H, t, J = 4.8
Hz, SO2O-CH2), 7.34 (2H, d, J = 8.6 Hz, Ph-H), 7.79
(2H, d, J = 8.4 Hz, Ph-H).
3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]phenol
(7). Intoa200mLofthree-neckedflask, 2-[2-(2-methoxy-
ethoxy)ethoxy]ethoxy-1-(4-methylbenzenesulfonate)
(6: 8.53 g, 26.8 mmol), resorcinol (5.90 g, 53.6 mmol),
K2CO3 (10 g) and acetonitrile (100 mL) were poured. It
was refluxed with stirring under a nitrogen atmosphere for
24 h.After complete reaction, the suspension was filtered.
The filtrate was concentrated under reduced pressure.
The residue was extracted with CH2Cl2 and washed
with water. The organic layer was dried over anhydrous
sodium sulfate and evaporated under reduced pressure.
The residue was purified by column chromatography
(silica gel, ethyl acetate:n-hexane = 2:1 (v/v), Rf = 0.45).
The product was obtained as yellow oil (2.43 g). Yield
35%. IR (KBr, cm-1): 3240 (-OH), 2924, 2879 (-CH2-),
2825 (-OCH3). 1H NMR (d6-DMSO, TMS): d, ppm 3.24
(3H, s, O-CH3), 3.42–3.58 (8H, m, O-CH2-CH2-O), 3.70
(2H, t, J = 4.7 Hz, O-CH2-CH2-O), 3.99–4.02 (2H, m,
PhO-CH2), 6.31–6.37 (3H, m, Ph-H), 7.04 (1H, t, J = 8.1
Hz, Ph-H).
Measurements
The compounds synthesized here were identified
1
with a H NMR (BRUKER Ultrashield 400 M Hz), an
elemental analyzer (Perkin-Elmer elemental analyzer
2400). The phase transition temperatures and enthalpy
changes were measured with a differential scanning
calorimeter (Shimadzu DSC-50). Electronic absorption
apectra of the phthalocyanine derivative were recorded
by using a HITACHI U-4100 spectrophotometer. The
textures of their mesophases were observed with a
polarizing optical microscope (Nikon ECLIPSE E600
POL) equipped with a Mettler FP82HT hot stage and
a Mettler FP90 Central Processor. Wide angle X-ray
diffraction measurements were carried out with Cu-Kα
radiation with a Rigaku RAD X-ray diffractometer
equipped with a handmade heating plate [26] controlled
with a thermoregulator.
4,5-bis[3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]-
phenoxy]phthalonitrile (8). Into a 50 mL of three
necked flask, 3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]-
phenol (7: 2.51 g, 9.48 mmol), 4, 5-dichlorophthalonitrile
(0.778 g, 3.95 mmol), K2CO3 (8 g) and dry N,
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1211–1216

1212 H. SATO ET AL.
Table 1. Phase transition temperatures and enthalpy change of [m-MeO(EtO)3PhO]8PcCu (4)
T, °C [ ∆ H /(kJ.mol-1)]
Phase
Phase
relaxation
132.0
Colho(v)
I.L.
very rapid cooling
136.0[12.9]
slow cooling
Colro(P21/a)
Phase nomenclature: Colho = hexagonal ordered columnar mesophase, Colro = rectangular ordered
columnar mesophase and I.L. = isotropic liquid. v = virgin state.
it is slowly heated from rt (Step 1),
it completely relaxes into the stable
mesophase of Colro(P21/a) (Step 2b) and
on further heating (Step 3), it cleared at
136.0 °C. Once it is heated over the c.p.
of Colro(P21/a) at 136.0 °C and then the
resulted I.L. is slowly cooled (Step 4), it
gives the stable Colro(P21/a) mesophase
(Step 4). On the other hand, when I.L.
is very rapidly cooled into rt (Step 5), it
gives again the unstable Colho mesophase
without the relaxation into the stable
Colro(P21/a) mesopahse.
The stable Colro(P21/a) mesophase
gave a natural texture on very slow
cooling from the I.L., whereas the
unstable Colho mesophase could not
give a natural texture because it always
transformed into stable Colro mesophase
on slow cooling. Figure 2 shows a well-
Fig. 1. Free energy vs. temperature (G-T) diagram for [m-MeO(EtO)3PhO]8PcCu
(4). The intersection temperatures are measured points, but the actual slopes
are unknown. Step: (1) heating of Colho mesophase, (2) relaxation, (3) further
heating over clearing point, (4) cooling, and (5) supercooling
developed natural texture of the stable Colro(P21/a)
mesopahse of [m-MeO(EtO)3PhO]8PcCu (4). This
texture could be obtained at 79.0 °C, when the I.L. over
the c.p.s was very slowly cooled at a rate of 0.1 °C/min.
RESULTS AND DISCUSSION
Phase transition behavior
Table 1 shows the phase transition behavior of
[m-MeO(EtO)3PhO]8PcCu (4). As can be seen from this
table, the freshly prepared (virgin) sample of compound
4 showed a hexagonal ordered columnar (Colho) at room
temperature, and cleared into isotropic liquid (I.L.) at
132.0 °C. When the I.L. was slowly cooled, it transformed
into a rectangular ordered columnar (Colro(P21/a))
mesophase. When the I.L. was very rapidly cooled into
rt, the Colho mesophase was obtained again.
This unique phase transition behavior can be
rationally explained by using free energy vs. temperature
(G-T) diagram. Figure 1 illustrates a G-T diagram for
[m-MeO(EtO)3PhO]8PcCu (4). Compound 4 gives an
unstable Colho mesophase at rt for the virgin sample.
When it is rapidly heated from rt (Step 1), it clears
into I.L. at 132.0 °C with partially relaxing into another
more stable mesophase of Colro(P21/a) (Step 2a). When
Fig. 2. Texture of the Colro(P21/a) mesophase of
[m-MeO(EtO)3PhO]8PcCu (4) at 79.0 °C
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1212–1216

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 46 1213
This dendric texture is characteristic to a texture of Colr
mesophase.
Figure 3 shows X-ray diffraction patterns of the
virgin sample at rt and the non-virgin sample at 50 °C
for [m-MeO(EtO)3PhO]8PcCu (4). These X-ray data
are summarized in Table 2. As can be seen from this
table, the virgin sample gave (100), (110), (200), (210)
and (310) reflections from a 2D hexagonal lattice and
(001) reflection due to an intradimer stacking distance
(2h) in the low angle region. From these reflections, this
mesophase could be identified as a Colho mesophase.
The non-virgin sample at 50 °C gave nine reflections
from a rectangular lattice in the low angle region. In the
high angle region, the non-virgin sample gave a very
broad halo (#) due to the molten oligoether chains and a
very sharp peak (0 0 1) due to a stacking distance (h) at
3.45 Å. From these reflections, this mesophase could be
identified as a Colro mesophase.
It is noteworthy that the present stacking distance (h =
3.45 Å) is very short for a Colr mesophase. We thought
that such a short stacking distance of Colr mesophase
might have originated from the very small tilt angle of
molecules in the columns. We calculated the tilt angle
from the slipped stacking structure illustrated in Fig. 4.
As can be seen from this figure, the disk-like molecules
pile up one-dimensionally with tilting to form the
columns in a Colro mesophase. Notations of a, b and q in
this figure represent the stacking distance, intermolecular
distance and tilted angle, respectively. The tilted angle q
can be calculated from an equation: q = arccos (b/a). The
stacking distance (a) is 3.45Å from the XRD measument.
The intermolecular distance (b) can be regarded to be
Fig. 3. XRD patterns of the virgin sample at rt and the
non-virgin sample at 50 °C for [m-MeO(EtO)3PhO]8PcCu (4).
h = Stacking distance, # = Halo
Table 2. X-ray data of [m-MeO(EtO)3PhO]8PcCu (4)
Miller
indices
(h k 1)
Mesophase
Lattice constants/Å
Spacing/Å
Observed Calculated
Colho at
vigrin sample at r.t.
a = 31.5
h = 9.26
Z = 2.1 for r = 1.0
27.2
15.8
14.2
10.3
9.26
7.68
ca. 4.2
27.2
15.7
13.6
10.3
—
(1 0 0)
(1 1 0)
(2 0 0)
(2 1 0)
2h
7.68
—
(3 1 0)
#
Colro (P21/a) at
nonvirgin sample at 50 ºC h = 3.45
a = 57.2 b = 37.9
31.6
28.6
23.4
19.1
16.9
14.5
10.7
9.76
7.54
ca. 4.2
3.45
31.6
28.6
22.8
18.9
17.0
14.3
10.5
9.79
7.56
—
(1 1 0)
(2 0 0)
(2 1 0)
(0 2 0)
(3 1 0)
(4 0 0)
(3 3 0)
(5 2 0)
(1 5 0)
#
Z = 1.8 for r = 1.0
—
h
#: Halo of the molten oligoether chains. h: Stacking distance.
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1213–1216

1214 H. SATO ET AL.
3.33 Å, which was observed as a stacking distance in the
Colho mesophase for the homologous phthalocyaninato
copper (II), (m-C12OPh)8PcCu (3), reported in our
previous work [23]. This stacking distance 3.33 Å can
be the intermolecular distance between phthalocyanine
disks due to van der Waals forces. Therefore, q = arccos
(3.33/3.45) = 15.2o. It is very interesting that the tilted
angle is very small in comparison with conventional Colro
mesophases.
Solubilities
In Table 3 the solubilities of a donor (p-type) of the
present [m-MeO(EtO)3PhO]PcCu complex (4) and an
acceptor (n-type) of the previous (C10O)16TzCu complex
(5) [23] are summarized. These solubilities were checked
for 1 mg of the sample in 1 mL of a solvent. The marks
of X, D and O mean “insoluble,” “partially soluble” and
“soluble,” respectively. In this table, the solvents are
listed in an order of their polarities. As can be seen from
this table, [m-MeO(EtO)3PhO]8PcCu (4) is insoluble in
Fig. 4. Structure of stacking in the Colro(P21/a) mesophase for
[m-MeO(EtO)3PhO]8PcCu (4)
Table 3. Solubilities of [m-MeO(EtO)3PhO]8PcCu (4) and (C10O)16TZCu (5)
 soluble, r partially soluble, × insoluble, * antagonist solubility.
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1214–1216

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 46 1215
Fig. 5. Photomicrographs of the thin films of [m-MeO(EtO)3PhO]8PcCu (4) and/or (C10O)16TZCu (5) on a glass plate
n-hexane, whereas it is soluble in many kinds of solvents
like toluene, chloroform~MeOH; and partially soluble
in diethyl ether and/or water. These good solubilities in
a polar solvent like acetone, ethanol and methanol are
attributable to the oligoether chains in the derivatives 4.
On the contrary, (C10O)16TzCu (5) is soluble in
n-hexane~chloroform,THFanddichloromethane,whereas
it is insoluble in a polar solvent like as acetone~water.
Thus antagonist solubilities could be observed between
[m-MeO(EtO)3PhO]8PcCu (4) and (C10O)16TzCu (5).
Antagonist solubility means that one compound is soluble
but another compound is insoluble in the same solvent.
As can be seen from Table 3, the antagonist solubilities
between [m-MeO(EtO)3PhO]8PcCu (4) and (C10O)16TzCu
(5) appear in an apolar solvent of n-hexane and polar
solvents of acetone, ethanol and methanol.
onto a glass plate. As can be seen from Figs 5c and 5d,
the compounds 4 and 5 did not mingle with each other
but layered. These successful double thin films are
attributable to the antagonist solubilities of 4 and 5 in
ethanol (Table 3). Thus, we succeeded in preparation of
a p-n junction of the doubly layered thin films by using
antagonist solubility.
CONCLUSION
We successfully synthesized a novel phthalocyaninato
copper (II) complex, [m-MeO(EtO)3PhO]8PcCu (4)
substituted by hydrophilic oligoether chains at the
m-positions of phenoxy groups. Very interestingly,
the complex 4 showed a hexagonal ordered columnar
(Colho) mesophase for the virgin sample, whereas it
showed a rectangular ordered columnar (Colro(P21/a))
mesophase for the non-virgin sample. Moreover, the
Colho mesophase gave a dimer stacking distance at
9.26 Å, whereas the Colro mesophase gave a short
monomer stacking distance at 3.45 Å. The complex
4 is readily soluble in polar solvents such as acetone,
ethanol and methanol, which is attributable to the
oligoether chains. Antagonist solubilities between
p-type of [m-MeO(EtO)3PhO]8PcCu (4) and n-type of
(C10O)16TzCu (5) enabled us to prepare a p-n junction
between the doubly layered thin films of 4 and 5. This
easy preparation method of a p-n junction can be applied
to organic thin film solar cell fabrications.
Preparation of a double thin film by using antagonist
solubility
Next we prepared a double thin film by using the
antagonist solubilities of 4 and 5 in ethanol, in order to
obtain the p-n junction. Figures 5a and 5b show two single
thin films prepared by casting an ethanol solution of
[m-MeO(EtO)3PhO]8PcCu (4) and a chloroform solution
of (C10O)16TzCu (5) onto a glass plate, respectively.
Figures 5c and 5d show two double thin films prepared
by casting the ethanol solution of 4 onto the thin film
previously prepared by casting the chloroform solution
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1215–1216

1216 H. SATO ET AL.
Acknowledgements
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This work is partially supported by Grant-in-Aid
for science research (Grant No. 2236012311) from
the Ministry of Education, Culture, Sports, Science
and Technology, Japan. We are grateful to Associate
Professor Mikio Yasutake, Saitama University for his
kind measurements of TOF-MASS spectrum of our
compound.
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