Discotic liquid crystals of transition metal complexes 56 ?: Synthesis of mesogenic phthalocyanine-fullerene dyads and influence of the substitution position of alkoxy chains and the kind of terminal groups on appearance of the helical supramolecular stru

Article abstract of DOI:10.1142/S108842461850092X

We have synthesized twelve novel discotic columnar liquid crystals based on a phenoxy-group-substituted phthalocyaninato copper(II) complex having the same alkoxy chain of C16H33O at different positions in the phenoxy group: The parent compounds {0a~0c-16

Full text of DOI:10.1142/S108842461850092X

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2018; 22: 1–23
DOI: 10.1142/S108842461850092X
Published at http://www.worldscinet.com/jpp/
Discotic liquid crystals of transition metal complexes 56†:
Synthesis of mesogenic phthalocyanine-fullerene dyads
and influence of the substitution position of alkoxy chains
and the kind of terminal groups on appearance of the helical
supramolecular structure
Kohei Ishikawaa, Ayumi Wataraia, MikioYasutakeb and Kazuchika Ohta*a
aSmart Material Science and Technology, Interdisciplinary Graduate School of Science and Technology,
Shinshu University, 1-15-1 Tokida, Ueda, 386-8567, Japan
bComprehensive Analysis Center for Science, Saitama University, 255 Shimo-okubo, Sakura-ku,
Saitama 338-8570, Japan
Received 23 May 2018
Accepted 21 June 2018
ABSTRACT: We have synthesized twelve novel discotic columnar liquid crystals based on a phenoxy-
group-substituted phthalocyaninato copper(II) complex having the same alkoxy chain of C16H33O at
different positions in the phenoxy group: the parent compounds {0a~0c-16} and the OH-substituted
compounds {3a~3c-16}, the OFBA-substituted compounds {2a~2c-16} and the C60-substituted dyads
{1a~1c-16}. The letters of a, b and c mean substitution positions of C16H33O group at m-, p- and m,p-,
respectively. We have investigated the influence of both substitution position of the alkoxy chains and
the kind of terminal groups (OH, OFBA and C60) on the mesomorphism and the helical supramolecular
structure, by using DSC, POM and temperature-variable small angle X-ray diffraction measurements.
As a result, an additional big peak (Peak H) tends to appear at around 2q = 1.1° in the X-ray diffraction
patterns only for the dyads {1a~1c-16} but not for the other compounds, {0a~0c-16}, {3a~3c-16} and
{2a~2c-16}, regardless of the substitution positions of the alkoxy group. Moreover, we revealed that
both the m-substituted derivative 1a-16 and the m,p-substituted derivative 1c-16 gave Peak H, but that
only the p-substituted derivative 1b-16 did not give Peak H among these three dyads {1a~1c-16}. From
the temperature-variable small angle X-ray diffraction measurements for the m,p-substituted derivative
1c-16 using two different sample preparation methods, we proved that the Peak H originates from a
helical pitch of fullerenes. We also pointed out that the m-substituted long alkoxy chains are at least
needed to form the helical supramolecular structure in the present (PhO)6PcM-C60-based dyads.
KEYWORDS: phthalocyanine, fullerene, columnar mesophase, homeotropic alignment, helical
supramolecular structure, substitution position effect.
molecule have been investigated toward high conversion
INTRODUCTION
efficiency of organic thin film solar cells [2–26]. Such a
In recent years, liquid crystalline dyads covalently
D–A liquid crystalline dyad may provide efficient charge
bonded between a donor (D) molecule and an acceptor (A)
separation within a molecule. If the D–A liquid crystalline
dyad would additionally show spontaneous perfect
homeotropic alignment between two electrode plates, one
dimensional nano-array structure [27] would be achieved
to realize much higher conversion efficiency. However,
*Correspondence to: Kazuchika Ohta, tel.: +81 268-24-2796,
fax: +81 268-24-2796, email: ko52517@shinshu-u.ac.jp.
†Part 54: Ref. [1].
Copyright © 2018 World Scientific Publishing Company

2
K. ISHIKAWA ET AL.
the relationship between the molecular structures of
dyads and the liquid crystalline phase supramolecular
structures has never been clarified to date.
and they also formed a helical supramolecular structure
for C60 moieties and gave a big Peak H in the X-ray
diffraction patterns [22, 24]. By using both Method A
(for random alignment) and Method C (for homeotropic
alignment) for the same sample, it was proven that the
Peak H originates from a helical pitch of C60 moieties
[21, 22, 24, 25]. The helical supramolecular structure
model is illustrated in the lower left of Fig. 1. This unique
structure resembles a spiranthes flower shown in the
lower right of Fig. 1, so that it was named “spiranthes-
like supramolecular structure” [22, 24, 25].
In 2010, another research group synthesized a
p-substituted (PhO)6PcM-C60-based dyad (p-C12OPhO)6-
PcZn-OPh-C60 [= ZnPc-C60], which very much resembled
our m,p-substituted dyads [m,p-(C12O)2PhO]6PcM-
Cm-C60, and they also reported that spherical C60 moieties
were helically stacked around the column formed by
disk-like Pc moieties [10, 15, 16, 26]. This p-substituted
dyad showed a Peak H as only a very small shoulder (see
Fig. 2(d) in Ref. 16), whereas our m,p-substituted dyads
showed it as an extremely big clear peak [21, 22, 24, 25].
Moreover, this PcZn-C60 dyad shows only rectangular
columnar (Colr) phases, so that the dyad cannot achieve
homeotropic alignment. In principle, only hexagonal
columnar (Colh) and tetragonal columnar (Coltet) phases
can give a homeotropically aligned samples [28].
In 2007, we succeeded for the first time the synthesis
of phthalocyanine-fullerene (Pc-C60) dyads showing
perfect homeotropic alignment [3]. Thereafter, we have
synthesized several kinds of liquid crystalline Pc-C60
dyads, and found that some of them also showed a
perfect homeotropic alignment [5, 8, 9, 11–14, 19–22,
24, 25]. During our research on such liquid crystalline
Pc-C60 dyads, we accidentally found that the spherical
C60 moieties helically pile up around the column formed
by disk-like Pc moieties in some of these columnar
mesophases. The helical supramolecular structure was
established by using temperature-variable small angle
X-ray diffraction measurements [5, 8, 9, 11–14, 21,
22, 24, 25]. Figure 1[a] illustrates a series of the liquid
crystalline Pc-C60 dyads [m,p-(C12O)2PhO]6PcM-Cm-C60
(M = Co, Ni, Cu; m = 6,8,10,12), which show helical stack
of the C60 moieties around the column formed by the Pc
moieties (see Fig. 1). The small angle X-ray diffraction
gave an additional big peak due to the helical pitch
(hereafter named as Peak H) in the extremely low angle
region around 2q @ 1.0° (= ca. 80 Å) [21]. Furthermore,
we synthesized another novel series of liquid crystalline
Pc-C60 dyads (CnS)6PcCu-Cm-C60 illustrated in Fig. 1[b],
Fig. 1. Liquid crystalline PcM-C60 dyads showing spiranthes-like supramolecular structure in homeotropic alignment
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 2–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
3
(4:0) compounds
(3:1) compounds
This work (n = 16)
Peak H ?
This work (n = 16)
Peak H ?
OR
RO
OR
RO
O
O
O
O
OR
OR
OR
OR
OR
N
N
N
N
Cu
N
N
N
N
O
O
O
O
N
N
CuN
O
OC12H24
O
O
N
N
N
N
N
N
OR
O
O
O
O
OR
RO
OR
RO
0a-16: (m-C16OPhO)8PcCu
1a-16: (m-C16OPhO)6PcCu-C60
OR
OR
RO
RO
This work (n = 16)
Peak H ?
This work (n = 16)
Peak H ?
O
O
O
O
OR
RO
RO
RO
N
N
N
N
N
N
O
O
O
O
O
O
N Cu N
N
N CuN
N
N
OC12H24
O
N
N
N
N
OR
RO
O
O
O
O
OR
OR
RO
RO
0b-16: (p-C16OPhO)8PcCu
1b-16: (p-C16OPhO)6PcCu-C60
Previous work (n = 9-14)
Previous work (n = 8, 10)
Peak H appears*2
No Peak H*1
OR
OR
RO
RO
RO
RO
This work (n = 16)
Peak H ?
This work (n = 16)
Peak H ?
OR
OR
O
O
O
O
OR
OR
OR
OR
OR
OR
RO
RO
RO
RO
N
N
N
N
N
Cu
N
N
Cu
N
O
O
O
O
N
N
N
N
N
N
N
O
OC12H24
O
O
N
N
OR
OR
O
O
O
O
OR
OR
RO
RO
OR
OR
R = CnH2n+1
RO
RO
0c-n: [m,p-(CnO)2PhO]8PcCu
1c-n: [m,p-(CnO)2PhO]6PcCu-C60
Fig. 2. Dependence of the substitution position of alkoxy chains on appearance of the helical pitch H of fullerene moieties in
columnar structure. *1: Ref. 28; *2: Refs. 5 and 21
Therefore, we are very interested in the influence
of the substitution position of alkoxy chains on
homeotropic alignment and appearance of the helical
supramolecular structure (Peak H). In this work, we
planned to synthesize three different (PhO)6PcCu-C60-
based dyads: the m-substituted derivative 1a-16, the
p-substituted derivative 1b-16 and the m,p-substituted
derivative 1c-16, as illustrated in Fig. 2. For easy
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 3–23

4
K. ISHIKAWA ET AL.
comparison, the length of the chain (R=CnH2n+1) is
fixed to n = 16 and we have prepared the parent (4:0)
compounds {0a~0c-16} and their corresponding chil-
dren (3:1) compounds: the OH-substituted compounds
{3a~3c-16}, OFBA-substituted compounds {2a~2c-16}
and the C60-substituted compounds {1a~1c-16}. The
letters of a, b and c with the entry numbers mean the
m-substituted derivative, p-substituted derivative and
m,p-substituted derivative, respectively. For these twelve
novel Pc compounds, we have investigated the influence
of both substitution position of the alkoxy chains and
the type of terminal groups (OH, OFBA and C60) on the
mesomorphism, the homeotropic alignment, the stacking
distance h and appearance of the helical supramolecular
structure (Peak H).
(2.4 mL). The reaction mixture was heated at 120°C for
48 h with stirring under a nitrogen atmosphere. Then it
was extracted with ethyl acetate and washed with brine.
The organic layer was dried over Na2SO4 overnight and
evaporated in vacuo. The residue was purified by column
chromatography (silica gel, n-hexane : ethyl acetate =
3 : 2, Rf = 0.58) to afford 2.45 g of white solid. Yield:
53.5%. Mp: 29.8°C.
4-(12-Hydroxydodecyoxy)phthalonitrile (4). To
a
three-necked flask were added dry DMF (24 mL), 4-
hydroxyphthalonitrIile (0.627 g, 4.43 mmol), K2CO3
(1.0 g) and 12-bromododecan-1-ol (6: 1.52 g, 5.72 mmol).
The reaction mixture was heated at 100°C for 1 h with
stirring under a nitrogen atmosphere. Then it was extracted
with chloroform and washed with brine. The organic layer
was dried over Na2SO4 overnight and evaporated in vacuo.
The residue was purified by column chromatography
(silica gel, chloroform: ethyl acetate = 4 : 1, Rf = 0.48) to
give 0.597 g of white solid.Yield: 82.6%. Mp: 69.5°C (lit.:
69.7°C [20]).
EXPERIMENTAL
Synthesis
1H-NMR (400 Mhz; CDCl3; TMS): d, ppm 1.20–
1.84 (20 H, m), 3.64 (2H, dd, J1 = 12.0 Hz, J2 = 6.4 Hz,
-OCH2CH2-), 4.04 (2H, t, J = 6.6 Hz, -OCH2-), 7.17 (1 H,
dd, J = 8.6 Hz, J = 2.6 Hz, Ar-H), 7.25 (1H, d, J = 2.4 Hz,
Ar-H), 7.69 (1 H, d, J = 9.2 Hz, Ar-H).
The syntheses of this study were carried out with
reference to our previously reported methods [20,
21, 28–30], as illustrated in Scheme 1. The detailed
procedures are described in the following.
3-Hexadecylphenol (7). To a three-necked flask were
added dry DMF (50 mL), resorcinol (6.14 g, 0.0560 mol),
1-bromohexadecane (17.7 g, 0.058 mol) and K2CO3
12-Bromododecan-1-ol (6). To a three-necked flask
were added dry toluene (52 mL), dodecane-1,12-diol
(3.49 g, 17.2 mmol) and 46% aqueous solution of HBr
OH
OR
RO
RO
RBr
HO
HO
RBr
RO
RO
OH
OH
OH
CHO
CHO
(i)
(ii)
(i)
11
10
R = C16H33
7
R = C16H33
HOC12H24OH
NC
NC
Cl
Cl
NC
NC
Cl
Cl
(iII)
(iII)
(iv)
BrC12H24OH
(v)
Xm
6
NC
NC
Cl
Cl
Xp
NC
NC
RO
NC
NC
O
O
RO
RBr HO
+
OH
OC12H25OH
CHO
(ii)
(i)
(iII)
CHO
CN
CN
9
8
Xp
4
HO
R = C16H33
Xm
a-n
b-n
c-n
5a~c
(vi)
Xm
Xp
OR
H
H
OR
OR
OR
Xp
Xp
Xm
Xp
Xm
=
Xp
Xp
Xp
Xm
,
,
Xm
Xm
Xm
R = C16H33
O
O
O
O
O
O
Xm
Xm
Xp
Xm
Xp
Xp
N
N
N
N
N
N
N
N
N
N
N
N
N
Cu
N
O
O
O
O
O
O
Cu N
N
N
N
Cu N
N
N
N
OC12H24
O
OC12H24OH
OC12H24 O
(viii)
(vii)
N
N
Xp
Xp
Xp
CHO
N
Xm
Xm
Xm
O
O
O
O
O O
Xm
Xp
Xm
Xp
Xm
Xp
Xm
Xp
Xm
Xm
Xp
Xp
1a~c
3a~c
2a~c
Scheme 1. Synthetic route of (m-C16OPhO)6PcCu-C60 (1a-16), (p-C16OPhO)6PcCu-C60 (1b-16) and [m,p-(C16O)2PhO]6PcCu-C60
(1c-16). (i) RBr/K2CO3/DMA; (ii) conc.H2SO4, 30% H2O2 aq., CHCl3, MeOH; (iii) K2CO3/DMA; (iv) 46% HBr aq./Toluene;
(v) K2CO3/DMF; (vi) DBU, 1-Hexanol, CuCl2; (vii) 4-Formylbenzoic acid, DCC, DMAP, CH2Cl2; (viii) N-Methylglycine, C60,
Toluene
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 4–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
5
(8.30 g). The reaction mixture was heated at 100°C
1H-NMR (400 MHz; CDCl3; TMS): d, ppm 0.81
(6H, t, J = 6.4 Hz, -CH3), 1.13–1.46 (52H, m), 1.78 (4H,
sextet, J = 6.8 Hz), 3.96–4:02 (4H, m), 6.88 (1 H, d,
J = 8.4 Hz, Ar-H), 7.33–7.36 (2H, m, Ar-H), 9.76 (1H,
s, -CHO).
3,4-Bis(hexadecyloxy)phenol (11). A mixture of
chloroform(20mL), 3,4-bis(hexadecyloxy)benzaldehyde
(10: 4.62 g, 0.00787 mmol), 30% H2O2 aq (8.5 g), H2SO4
(10 drops) and methanol (31 mL) was added to an
Erlenmeyer flask and stirred at room temperature for 24 h
with blocking out of the light. Then the reaction mixture
was extracted with chloroform and washed with brine
three times. The organic layer was dried over Na2SO4 and
evaporated in vacuo. The residue was recrystallized from
n-hexane to give 3.54 g of white solid.Yield: 80.1%. Mp:
94.1°C.
for 1 h with stirring under a nitrogen atmosphere.
Then it was extracted with chloroform and washed
with brine. The organic layer was dried over Na2SO4
and evaporated in vacuo. The residue was purified by
column chromatography (silica gel, chloroform, Rf =
0.24) to afford 3.30 g of white solid. Yield: 17.0%. Mp:
63.0°C.
1H-NMR (400 Mhz; CDCl3; TMS): d, ppm 0.88 (3H,
t, J = 7.2 Hz, -CH3), 1.21–1.47 (26H, m), 1.73–1.80 (2H,
m), 3.92 (2H, t, J = 6.4 Hz, -OCH2-), 4.71 (1H, s, -OH),
6.38–6.50 (3H, m, Ar-H), 7.09–7.13 (1H, m, Ar-H).
4-(Hexadecyloxy)benzaldehyde (8). To a three-necked
flask were added dry DMF (60 mL), 4-hydroxybenzalde-
hyde (3.00 g, 24.6 mmol), 1-bromohexadecane (8.23 g,
27.0 mmol) and K2CO3 (2.22 g). The reaction mixture was
refluxed for 2 h with stirring under a nitrogen atmosphere.
Then it was extracted with chloroform and washed with
water. The organic layer was dried over Na2SO4 and
evaporated in vacuo. The residue was purified by column
chromatography (silica gel, chloroform, Rf = 0.48) to give
6.50 g of white solid. Yield: 76.1%. Mp: 43.6°C.
1H-NMR (400 MHz; CDCl3; TMS): d, ppm 0.91 (6H,
t, J = 6.4 Hz, -CH3), 1.23–1.52 (53H, m), 1.74–1.86
(4H, m), 3.91–3.99 (4H, m), 6.32 (1H, dd, J1 = 2.8, J2 =
8.4 Hz, Ar-H), 6.47 (1H, d, J = 2.8 Hz, Ar-H), 6.78 (1H,
d, J = 8.4 Hz, Ar-H), 9.76 (s, -OH).
4,5-Bis(3-(hexadecyloxy)phenoxy)phthalonitrile
(5a). To a three-necked flask were added dry DMA
(10 mL), 3-(hexadecyloxy)phenol (7: 1.50 g, 4.49
mmol), 4,5-dichlorophthalonitrile (0.381 g, 1.93 mmol)
and K2CO3 (1.4 g). The reaction mixture was heated at
130°C for 2 h with stirring under nitrogen atmosphere.
Then it was extracted with chloroform and washed with
brine. The organic layer was dried over Na2SO4 overnight
and evaporated in vacuo. The residue was purified by
column chromatography (silica gel, chloroform, Rf =
0.71) to afford 1.00 g of white solid. Yield: 65.3%. Mp:
73.5°C (lit; 73.2°C [21]).
1H-NMR (400 Mhz; CDCl3; TMS): d, ppm 0.90 (3H,
t, J = 6.4 Hz, -CH3), 1.23–1.52 (26H, m), 1.79–1.87 (2H,
m), 4.02 (2H, t, J = 6.4 Hz), 6.99–7.05 (2H, m, Ar-H),
7.83–7.87 (2H, m, Ar-H), 9.90 (1H, s, -CHO).
4-(Hexadecyloxy)phenol (9). A mixture of chloroform
(60 mL), 4-(hexadecyloxy)benzaldehyde (8: 4:07 g, 11.5
mmol), 30% H2O2 aq (9.8 g), H2SO4 (15 drops) and
methanol (43 mL) was added to an Erlenmeyer flask
and stirred at room temperature for 46 h with blocking
out of the light. The reaction mixture was extracted with
chloroform and washed with brine. The organic layer
was dried over Na2SO4 and evaporated in vacuo. The
residue was purified by column chromatography (silica
gel 150 g, chloroform, Rf = 0.18) to afford 2.07 g of white
solid. Yield: 53.6%. Mp: 86.2°C.
1H-NMR (400 MHz; CDCl3; TMS): d, ppm 0.88 (3H,
t, J = 6.4 Hz, -CH3), 1.20–1.49 (26H, m), 1.75–1.82 (2H,
m), 3.95 (2H, t, J = 6.4 Hz, -OCH2-), 6.60–6.82 (6H, m,
Ar-H), 7.20 (2H, s, Ar-H), 7.32 (2H, t, J = 8.0 Hz, Ar-H).
4,5-Bis(4-(hexadecyloxy)phenoxy)phthalonitrile)
(5b). To a three-necked flask were added dry DMA
(20 mL), 4-(hexadecyloxy)phenol (9: 1.80 g, 5.38 mmol),
4,5-dichlorophthalonitrile (0.528 g, 1.9 mmol) and
K2CO3 (1.4 g). The reaction mixture was refluxed for
30 min with stirring under a nitrogen atmosphere. Then
it was extracted with chloroform and washed with brine.
The organic layer was dried over Na2SO4 overnight and
evaporated in vacuo. The residue was recrystallized
from ethanol to give 1.86 g of white solid. Yield: 87.6%.
Mp: 106.1°C.
1H-NMR (CD3SO; TMS): d, ppm 0.85 (3H, t, J = 6.8
Hz, -CH3), 1.19–1.42 (26H, m), 1.61–1.68 (2H, m), 3.82
(2H, t, J = 6.8 Hz), 6.62–6.74 (2H, m), 8.86 (1H, s, -OH).
3,4-Bis(hexadecyloxy)benzaldehyde (10). To a three-
neckedflaskwereaddeddryDMF(20mL),3,4-dihydroxy-
benzaldehyde (3.04 g, 0.0220 mol), 1-bromohexadecane
(13.9 g, 0.0456 mol) and K2CO3 (3.04 g). The reaction
mixture was stirred at room temperature for 10 min under
N2 gas atmosphere, and then refluxed for 1 h with stirring.
It was checked by TLC (silica gel, chloroform) and found
the starting material of 3,4-dihydroxybenzaldehyde.
Accordingly, 1-bromohexadecane (6.91 g, 0.0226 mol)
was added to the reaction mixture. Since the starting
material disappeared after 4 h, the reaction mixture was
extracted with chloroform and washed with water three
times. The organic layer was dried over Na2SO4 overnight
and then evaporated in vacuo. The residue was purified
by column chromatography (silica gel, chloroform, Rf =
0.58) to afford 10.3 g of white solid. Yield: 79.6%. Mp:
80.4°C.
1H-NMR (400 MHz; CDCl3; TMS): d, ppm 0.88 (6H,
t, J = 6.8 Hz, -CH3), 1.13–1.51 (52H, m), 1.81 (4H, quint,
-CH2-), 3.98 (4H, t, J = 6.4 Hz, -O-CH2-), 6.95–7.05
(10H, m, Ar-H).
4,5-Bis(3,4-bis(hexadecyloxy)phenoxy)phthalo-
nitrile (5c). To a three-necked flask were added dry
DMA (20 mL), 4,5-dichlorophthalonitrile (157.7 mg,
0.800 mol), 3,4-bis(hexadecyloxy)phenol (11: 1.00 g,
1.74 mmol) and K2CO3 (3.49 g). The reaction mixture
Copyright © 2018 World Scientific Publishing Company
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6
K. ISHIKAWA ET AL.
was stirred at room temperature for 10 min and then
refluxed for 2 h with stirring under a nitrogen atmosphere.
It was extracted with chloroform and washed with brine.
The organic layer was dried over Na2SO4 overnight and
evaporated in vacuo. The residue was purified by column
chromatography (silica gel, chloroform, Rf = 0.71) to
afford 655.2 mg of white solid.Yield: 64.2%. Mp: 96.2°C.
1H-NMR (400 MHz; CDCl3; TMS): d, ppm 0.81 (12 H,
t, J = 6.4 Hz, -CH3), 1.19–1.43 (104 H, m), 1.72–1.79
(8 H, m), 3.89 (4H, t, J = 6.4 Hz), 3.95 (4H, t, J = 6.4 Hz,
-OCH2-), 6.52–6.59 (4H, m, Ar-H), 6.84 (2H, d, J = 8.8
Hz, Ar-H), 7.02 (2H, s, Ar-H).
(m-C16OPhO)6PcCu-OH (3a-16). To a three-necked
flask were added 1-hexanol (30 mL), 4-(12-hydroxydo-
decyoxy)phthalonitrile (4: 0.108 g, 0.327 mmol), 4,5-
bis(3-(hexadecyloxy)phenoxy)phthalonitrile (5a: 0.731 g,
0.922 mmol) and CuCl2 (0.0512 g, 0.0381 mmol). The
reactionmixturewasstirredatroomtemperaturefor10min
and then DBU (3 drops) was added. It was heated at 160°C
for 24 h with stirring under a nitrogen atmosphere. After
cooling to room temperature, methanol was poured into
the reaction mixture to precipitate the target compound.
The precipitate was collected by filtration, washed with
methanol, ethanol and acetone successively. Chloroform
was added, and the solvent was then evaporated in vacuo.
The residue was purified by column chromatography
(silica gel, chloroform) to remove a by-product of the (4:0)
parent PcCu compound (0a-16: Rf = 1.00) and collected
the (3:1) target PcCu compound (3a-16: Rf = 0.34). After
removal of the solvent, 237.9 mg of green solid was
obtained in yield 18.0%.
Phase transition behavior: See Table 3.
(m,p-C16OPhO)6PcCu-OH (3c-16). To a three-necked
flask were added 1-hexanol (15 mL), 4-(12-hydroxydo-
decyoxy)phthalonitrile (4: 0.606 g, 0.476 mmol), 4,5-bis-
(4-(hexadecyloxy)phenoxy)phthalonitrile (5c: 0.055 g,
0.167 mol), and CuCl2 (29.2 mg, 0.217 mmol). The reaction
mixture was stirred at room temperature for 10 min and then
DBU (3 drops) was added. It was heated at 160°C for 20 h
with stirring under a nitrogen atmosphere. After cooling to
room temperature, methanol was poured into the reaction
mixture to precipitate the target compound. The precipitate
was collected by filtration, washed with methanol, ethanol
and acetone successively. Chloroform was added, and the
solvent was then evaporated in vacuo. The residue was
purified by column chromatography (silica gel, toluene) to
remove a by-product of the (4:0) parent PcCu compound
(0c-16: Rf = 1.00) and collected the (3:1) target PcCu
compound (3c-16: Rf = 0.70). After removal of the solvent,
243 mg of green solid was obtained in yield 34.1%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
(m-C16OPhO)6PcCu-OFBA (2a-16). To
a three-
necked flask were added dry 1,2-dichloroethane (20 mL),
(m-C16OPhO)6PcCu-OH (3a-16: 0.153 g, 0.0555 mmol),
4-formylbenzoic acid (0.0165 g, 0.110 mmol), DMAP
(0.0473 g, 0.387 mmol) and DCC (0.143 g, 0.6952 mmol).
The reaction mixture was refluxed with stirring for 45 h
under a nitrogen atmosphere. After cooling to room
temperature, methanol was poured into the reaction
mixture to precipitate the target compound. The precipitate
was collected by filtration, washed with methanol, ethanol
and acetone successively. Chloroform was added, and the
solvent was then evaporated in vacuo. The residue was
purified by column chromatography (silica gel, chloroform,
Rf = 0.78) to afford 0.0259 g of green solid in yield 16.1%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
(p-C16OPhO)6PcCu-OH (3b-16). To a three-necked
flask were added 1-hexanol (60 mL), 4-(12-hydroxydo-
decyoxy)phthalonitrile (4: 0.209 g, 0.636 mmol), 4,5-bis-
(4-(hexadecyloxy)phenoxy)phthalonitrile (5b: 1.04 g,
1.77 mmol) and CuCl2 (0.108 g, 0.803 mmol). The reaction
mixture was stirred at room temperature for 10 min and
then DBU (3 drops) was added. It was heated at 160°C
for 24 h with stirring under a nitrogen atmosphere. After
cooling to room temperature, methanol was poured into
the reaction mixture to precipitate the target compound.
The precipitate was collected by filtration, washed with
methanol, ethanol and acetone successively. Chloroform
was added, and the solvent was then evaporated in vacuo.
The residue was purified by column chromatography
(silica gel, chloroform) to remove a by-product of the (4:0)
parent PcCu compound (0b-16: Rf = 1.00) and to collect
the (3:1) target PcCu compound (3b-16: Rf = 0.18). After
removal of the solvent, 346 mg of green solid was obtained
in yield 20.5%.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
(p-C16OPhO)6PcCu-OFBA (2b-16). To a three-necked
flask were added dry toluene (20 mL), (p-C16OPhO)6-
PcCu-OH(3b-16:0.142g, 0.0513mmol), 4-formylbenzoic
acid (0.0154 g, 0.103 mmol), DMAP (0.0250 g, 0.205
mmol) and DCC (0.106 g, 0.0513 mmol). The reaction
mixture was stirred at room temperature for 3 h and
then refluxed with stirring for 24 h under a nitrogen gas
atmosphere. After cooling to room temperature, methanol
was poured into the reaction mixture to precipitate
the target compound. The precipitate was collected by
filtration, washed with methanol, ethanol and acetone
successively. Chloroform was added, and the solvent
was then evaporated in vacuo. The residue was purified
by column chromatography (silica gel, chloroform:
dichloromethane = 1:1, Rf = 0.78) to afford 163.0 mg of
green solid in yield 75.4%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
UV-vis spectral data: See Table 2.
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DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
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}
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DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
9
Table 3. Phase transition temperatures and enthalpy changes of 0a~0c-16, 3a~3c-16, 2a~2c-16 and 1a~1c-16
T/oC [∆H(kJmol-1)]
Compound
Phase
Phase
34.5 [64.8]
160.9 [18.0]
0a-16: (m-C16OPhO)8PcCu*1
K
K
Colho
Colhd
I.L.
I.L.
116.0[157.2]
266.5[7.15]
0b-16: (p-C16OPhO)8PcCu
0c-16: [m,p-(C16O)2PhO]8PcCu
163.8 [2.15]
201.4 [8.31]
117.2 [95.3]
157.6 [17.6]
[73.2]
55.6 [126.9]
Colhd
Coltet.d
K
I.L.
I.L.
3a-16: (m-C16OPhO)6PcCu-OH
83.4 [0.368]
Colho1
Colho3
Colho2
34.1
K1v
3b-16: (p-C16OPhO)6PcCu-OH
235.5 [6.69]
148.3 [1.57]
56.1
K2v
Colho
I.L.
I.L.
86.5[8.55]
K3v
3c-16: [m,p-(C16O)2PhO]6PcCu-OH
52.6 [205.4]
121.6 [22.3]
Colhd
Coltet.d
K
157.3 [22.8]
92.3 [10.9]
72.6[197.4]
193.2 [14.2]
245.7 [6.00]
94.7[42.1]
2a-16: (m-C16OPhO)6PcCu-OFBA
2b-16: (p-C16OPhO)6PcCu-OFBA
Colho2
Colho
I.L.
I.L.
Colho1
K
2c-16: [m,p-(C16O)2PhO]6PcCu-OFBA
Colhd
I.L.
K
148.0 [24.8]
1a-16: (m-C16OPhO)6PcCu-C60
1b-16: (p-C16OPhO)6PcCu-C60
Colho
Colho
I.L.
I.L.
84.7 [1.47]
139.1 [3.79]
93.8 [31.8]
K
K
59.8 [220.3]
1c-16: [m,p-(C16O)2PhO]6PcCu-C60
Colhd
I.L.
*Phase nomenclature: K = crystal, Colho = hexagonal ordered columnar mesophase, Colhd = hexagonal disordered
columnar mesophase, Coltet.o = tetragonal ordered columnar mesophase, Coltet.d = tetragonal disrodered columnar
mesophase, Colro = rectangular ordered columnar mesophase, and I.L, = isotropic liquid, v = virgin sample.
=
mesophase showing homeotropic alignment.
*1: Ref. 31.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
(18.7 mg, 0.153 mmol) and DCC (71.4 mg, 0.346 mmol).
The reaction mixture was stirred at room temperature for
3 h under a nitrogen atmosphere. It was checked by TLC
(silica gel, chloroform) and the starting material of (m,p-
C16OPhO)6PcCu-OH (3c-16) was found. Accordingly,
4-formylbenzoic acid (29.9 mg, 0.199 mmol), DMAP
(49.1 mg, 0.4:02 mmol) and DCC (132.6 mg, 0.643 mmol)
were added and it was refluxed for an additional 5 h with
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
(m,p-C16OPhO)6PcCu-OFBA (2c-16). To a three-
necked flask were added dry toluene (20 mL), (m,p-
C16OPhO)6PcCu-OH (3c-16: 0.143 g, 0.0339 mmol),
4-formylbenzoic acid (11.2 mg, 0.0746 mmol), DMAP
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K. ISHIKAWA ET AL.
stirring under a nitrogen atmosphere. After cooling to
room temperature, methanol was poured into the reaction
mixture to precipitate the target compound. The precipitate
was collected by filtration, washed with methanol, ethanol
and acetone successively. Chloroform was added, and the
solvent was then evaporated in vacuo. The residue was
purified by column chromatography (silica gel 140 g,
chloroform : toluene = 1:1, Rf = 0.83) to afford 83.3 mg
of green solid in yield 56.6%.
to room temperature, the solvent was evaporated in vacuo.
The residue was purified by column chromatography
(Silica gel 100 g, chloroform, Rf = 0.95) and then by
HPLC (Japan Analytical Industry Co. Ltd. LC-918) to
afford 16.8 mg of green solid in yield 34.1%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
Elemental analysis and MALDI-TOF mass data:
see Table 1.
Measurements
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
HPLC was carried out by using an LC-9110 NEXT
recycling preparative from Japan Analytical Industry Co.
Ltd. The infrared absorption spectra were recorded by using
(m-C16OPhO)6PcCu-C60 (1a-16). To a three-necked
flaskwereaddeddrytoluene(40mL),(m-C16OPhO)6PcCu-
OFBA (2a-16: 80.8 mg, 0.0278 mmol), fullerene
(40.9 mg, 0.0568 mmol) and N-methylglycine (6.0 mg,
0.0673 mmol). The reaction mixture was refluxed for
12 h with stirring under a nitrogen atmosphere. After
cooling to room temperature, methanol was poured into
the reaction mixture to precipitate the target compound.
The precipitate was collected by filtration, washed with
methanol, ethanol and acetone successively. Chloroform
was added, and the solvent was then evaporated in vacuo.
The residue was purified by column chromatography
(silica gel 100 g, chloroform: n-hexane = 2 : 5, Rf = 0.93)
and then by HPLC (Japan Analytical Industry Co. Ltd.
LC-918) to afford 20.8 mg of green solid in yield 20.2%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
1
a Nicolet NEXUS 670 FT-IR spectrometer. The H-NMR
measurements were carried out by using a Bruker Ultra-
shield 400 MHz. The elemental analyses were performed
by using a Perkin–Elmer Elemental Analyzer 2400. The
MALDI-TOF mass spectral measurements were carried out
byusingaBrukerDaltonicsAutoflexIIIspectrometer(matrix:
dithranol). Table 1 summarizes the elemental analysis and
MALDI-TOF mass data. Electronic absorption (UV-vis)
spectra were recorded by using a Hitachi U-4100 spectro-
photometer. Table 2 summarizes these UV-vis spectral
data. Phase transition behavior of the present compounds
was observed with a polarizing optical microscope (Nikon
ECLIPSE E600 POL) equipped with a Mettler FP82HT
hot stage and a Mettler FP90 Central Processor, and a
Shimadzu DSC-50 differential scanning calorimeter. The
mesophases were identified by using a small angle X-ray
diffractometer (Bruker Mac SAXS System) equipped with a
temperature-variable sample holder adapted from a Mettler
FP82HT hot stage. The phase transition temperatures and
the transition enthalpy changes are listed in Table 3. Figs. 3
and 4 illustrate the setup of the SAXS system and the setup
of the temperature-variable sample holder, respectively. As
can be seen from Fig. 3, the generated X-ray is bent by two
convergence monochrometers to produce a point X-ray
beam (diameter = 1.0 mm). The point beam runs through
the holes of the temperature-variable sample holder. As
illustrated in Fig. 4, into the temperature-variable sample
holder of Mettler FP82HT hot stage, a glass plate (76 mm ×
19 mm × 1.0 mm) with a hole (diameter = 1.5 mm) is
inserted. The hole can be charged with a powder sample
(ca. 1 mg). The measurable range is from 3.0Å to 110Å and
the temperature range is from room temperature to 375°C.
This SAXS system is available for all condensed phases
including the fluid nematic phase and isotropic liquid.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
(p-C16OPhO)6PcCu-C60 (1b-16). To a three-necked
flaskwereaddeddrytoluene(20mL),(p-C16OPhO)6PcCu-
OFBA (2b-16: 73.2 mg, 0.0252 mmol), fullerene
(37.3 mg, 0.0518 mmol) and N-methylglycine (5.7 mg,
0.0640 mmol). The reaction mixture was refluxed for
16 h with stirring under a nitrogen atmosphere. After
cooling to room temperature, methanol was poured into
the reaction mixture to precipitate the target compound.
The precipitate was collected by filtration, washed with
methanol, ethanol and acetone successively. Chloroform
was added, and the solvent was then evaporated in vacuo.
The residue was purified by column chromatography
(silica gel 100 g, chloroform : n-hexane = 2 : 5, Rf = 0.65)
and then by HPLC (Japan Analytical Industry Co. Ltd.
LC-918) to afford 58.1 mg of green solid in yield 63.1%.
Elemental analysis and MALDI-TOF mass data: See
Table 1.
UV-vis spectral data: See Table 2.
Phase transition behavior: See Table 3.
RESULTS AND DISCUSSION
(m,p-C16OPhO)6PcCu-C60 (1c-16). To a three-necked
flask were added dry toluene (20 mL), (m,p-C16OPhO)6-
PcCu-OFBA (2c-16: 42.2 mg, 0.00970 mmol), fullerene
(14.1 mg, 0.0196 mmol) and N-methylglycine (2.8 mg,
0.0314 mmol). The reaction mixture was refluxed for 24 h
with stirring under a nitrogen atmosphere. After cooling
Synthesis
Table 1 lists MALDI-TOF mass and the elemental
analysis data for all the PcCu products. As can be seen
from this table, the observed values agree well with
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DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
11
Fig. 3. Setup of small angle X-ray scattering (SAXS) apparatus equipped with a temperature-variable sample holder
Fig. 4. Setup of the temperature-variable sample holder
the theoretical values for both the TOF mass and the
elemental analyses for all the PcCu products, so that it was
confirmed that all the target products were successfully
synthesized. The (PhO)6PcCu-C60 dyads 1a~1c-16 were
not completely combustible so that the element analyses
could not be effective. However, it was confirmed from
the MALDI-TOF mass spectra and ultraviolet-visible
absorption spectra that the (PhO)6PcCu-C60 dyads 1a~1c-
16 were successfully synthesized. As can be seen from
Table 2, each of the (PhO)6PcCu-C60 dyads 1a~1c-16
gives both the Q0-0 band around 683 nm characteristic to
PcCu having D4h symmetry and the band at 253–255 nm
due to fullerene (C60). From these results, we could judge
that the target (PhO)6PcCu-C60 dyads 1a~1c-16 were
certainly synthesized.
Phase transition behavior
Table 3 shows the phase transition behavior of the
parent (4:0) compounds {0a~0c-16} and their corres-
ponding children (3:1) compounds: the OH-substituted
compounds {3a~3c-16}, OFBA-substituted compounds
{2a~2c-16} and the C60-substituted compounds {1a~1c-
16}. The detailed phase transitions will be explained
below.
(4:0) Compounds {0a~0c-16}. As can be seen from
Table 3, the m-substituted derivative 0a-16 and the
p-substituted derivative 0b-16 showed only one columnar
liquid crystalline phase, Colho and Colhd, respectively.
The Colho phase of the p-substituted derivative 0b-16
cleared into an isotropic liquid at 266.5°C. This cp
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K. ISHIKAWA ET AL.
was much higher than those of the m-substituted
derivative 0a-16 and the m,p-substituted derivative
0c-16. Unlike the m-substituted derivative 0a-16 and
the p-substituted derivative 0b-16, the m,p-substituted
derivative 0c-16 showed two kinds of columnar liquid
crystalline phases, Colhd and Coltet.d. More interestingly,
this high temperature mesophase Coltet.d showed perfect
homeotropic alignment between two glass plates (see
Fig. 5.) A similar homeotropic alignment was also
observed for the Coltet.d phases in the homologues 0c–0n
(n = 11–14) having different alkoxy chain length [28].
OH-substituted compounds {3a~3c-16}. As can be
seen from Table 3, the m-substituted derivative 3a-16 is
liquid crystalline at room temperature and showed three
is much higher than those of the m-substituted derivative
3a-16 and the m,p-substituted derivative 3c-16. The m,p-
substituted 3c-16 shows two different mesophases, Colhd
and Coltet.d, and the high temperature mesophase Coltet.d
shows perfect homeotropic alignment between two glass
plates (see Fig. 5). Thus, the mesomorphism of the m,p-
substituted derivative 3c-16 is exactly the same as that of
the corresponding parent (4:0) compound 0c-16.
OFBA-substituted compounds {2a~2c-16}. As
can be seen from Table 3, the m-substituted derivative
2a-16 shows a Colho1 mesophase at room temperature.
On heating from room temperature, it transformed into
another Colho2 mesophase and then into an isotropic liquid
(I.L.). On the other hand, the p-substituted derivative
2b-16 is crystalline at room temperature. On heating,
the crystalline K phase melts into a Colho phase and then
clears into an I.L. at a high temperature of 245.7°C,
which is much higher than those of the other derivatives
of m-substituted 2a-16 and m,p-substituted 2c-16. The
m,p-substituted derivative 2c-16 is also crystalline (K)
at room temperature, like the m-substituted derivative
2a-16. It melts into a Colhd phase at 59.8°C. The Colhd
different Colho phases from Colho1, Colho2 and Colho3
.
On the other hand, the p-substituted derivative 3b-16 is
crystalline at room temperature and shows a mixture of
three crystalline polymorphs K1, K2 and K3 as the virgin
state. Upon heating, each of the crystalline phases melted
into a Colho mesophase; on further heating, it cleared into
an isotropic liquid (I.L.) at a high temperature of 235.5°C.
The cp (235.5°C) of this p-substituted derivative 3b-16
Fig. 5. Photomicrographs of the phthalocyanine-based liquid crystals, 0a~0c-16, 3a~3c-16, 2a~2c-16 and 1a~1c-16
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DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
13
Fig. 5. (Continued)
phase of 2c-16 did not show homeotropic alignment,
unlike the corresponding parent (4:0) compound 0c-16
and the precursor 3c-16 (see Fig. 5).
{1a~1c-16} the m,p-substituted derivative 1c-16 only
shows homeotropic alignment, whereas neither the
m-substituted derivative 1a-16 nor the p-substituted
derivative 1b-16 shows homeotropic alignment. It is
noteworthy that the same tendency could be also observed
in the parent (4:0) compounds and the OH-substituted
compounds (see Fig. 5).
The homeotropic alignment of m,p-substituted 1c-16
was proved as shown in Fig. 6. A small amount of the
derivative 1c-16 was first sandwiched between two glass
plates and heated up over the cp to completely clear into
an isotropic liquid. The I.L. was cooled to 90°C in the
Colhd mesophase temperature range to obtain perfect
homeotropic alignment. The cover slip was removed at
this temperature, and the thin film was scratched with
a spatula or something like a needle. Figure 6 shows a
photomicrographofthescratchedsamplebetweencrossed
polarizers. As you can see from this photomicrograph,
only the scratched parts show birefringence while the
other parts are completely dark. As illustrated in the
C60-substituted compounds {1a~1c-16}. As shown
in Table 3, the m-substituted derivative 1a-16 exhibits a
Colho mesophase at room temperature. When heated it
cleared into an I.L. On the other hand, the p-substituted
derivative 1b-16 exhibits a crystal (K) at room
temperature. When heated, it melts into the Colho phase
and then clears into an I.L. When this I.L. was cooled
down to room temperature, it remained in the Colho phase
without recrystallization. The m,p-substituted derivative
1c-16 was in a crystalline phase (K) at room temperature,
like the p-substituted derivative 1b-16. On heating from
room temperature, it melted into the Colhd phase and
then cleared into I.L. When this I.L. was cooled down
to room temperature, it remained in the Colhd phase
without recrystallization. This Colhd mesophase showed
perfect homeotropic alignment between two glass plates
(see Fig. 5). Thus, in the C60-substituted compounds
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K. ISHIKAWA ET AL.
Fig. 6. Photomicrograph of the Colho mesophase of (m,p-C16OPhO)6PcCu-C60 (1c-16) at 90°C showing homeotropic alignment.
The dark area showed homeotropic alignment but the scratched part turned to show birefringence
figure, the columns are vertically oriented with respect
to the substrate in the homeotropic parts, so that the parts
give darkness under crossed Nicols. When you scratch
this thin film with a needle, birefringence will appear
due to the collapse of the vertically oriented columns
to show blight parts. In the case of isotropic liquid or
Cub phase, such birefringence does not appear. From
these microscopic observations, it was proven that the
m,p-substituted derivative 1c-16 was homeotropically
aligned.
Thus, only the m,p-substituted derivative 1c-16
exhibited homeotropic alignment in the (PhO)6PcCu-C60-
based complexes, and neither the m-substituted derivative
1a-16 nor a p-substituted derivative 1b-16 showed
homeotropic alignment. Therefore, large doubt remains
for the homeotropic alignment of the p-substituted
derivative (p-C12OPhO)6PcZn-OPh-C60 (= PcZn-C60)
reported by another research group [10, 15, 16, 26]. The
homeotropic alignment in their p-substituted derivative
should be proven by the above-described method using a
polarization microscope.
a homogeneously aligned sample gives the reflections
only from the 1D lattice in the Z-direction. In Method
C, a homeotropically aligned sample gives the reflections
only from the 2D lattice in the XY plane. If the peak H
were a periodicity along the Z-axis direction of column,
the peak H should disappear for the homeotropically
aligned sample in Method C [21].
Therefore, at first, it was investigated using Method
A whether or not each of the liquid crystalline phases
was identified and Peak H corresponding to the pitch
of the helix appeared. Figures 8, 9, 10 and 11 show
X-ray diffraction patterns of the parent (4:0) compounds
{0a~0c-16}, the OH-substituted compounds {3a~3c-16},
the OFBA-substituted compounds {2a~2c-16} and the
C60-substituted compounds {1a~1c-16}, respectively. All
the X-ray data are summarized in Table 4. The detailed
XRD results will be explained below.
(4:0) Compounds {0a~0c-16}. As can be seen from
Fig. 8, the m-substituted parent (4:0) compound 0a-16
shows three peaks from No. 1 to No. 3 in the low angle
region, and two peaks, No. 4 and No. 5, in the high
angle region, for the liquid crystalline phase at 100°C.
As can be seen from Table 4, these three peaks in the
low angle region were well assigned to (100), (110) and
(200) reflections from a 2D hexagonal lattice. A broad
peak No. 4 is attributed to a halo due to the molten alkyl
groups. Peak No. 5 was attributable to a (001) reflection
corresponding to stacking between Pc disks in the
columns. Therefore, this liquid crystal phase could be
identified as a hexagonal ordered columnar (Colho) phase.
From these assignments, the lattice constant a = 43.2 Å
of the 2D hexagonal lattice and the stacking distance
h = 3.39 Å were obtained. Assuming that the density of
Temperature-variable small angle X-ray
diffraction studies
Figure 7 illustrates three different measurement
methods for temperature-variable small angle X-ray
diffraction:
Method A: non-aligned sample;
Method B: homogeneously aligned sample of
ordered columns between two glass plates;
Method C: homeotropically aligned sample of
ordered columns between two glass plates.
In Method A, polydomain of liquid crystalline phase
is filled into a hole. In this case, the reflections both
from 2D and 1D lattices can be observed. In Method B,
3
.
the liquid crystalline phase was 1.0 g cm , the number
of molecules per unit lattice (Z) was calculated to be just
1.0. This Z value is consistent with a Colho phase [31].
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DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
15
As can be seen from Fig. 8, the mesophases in
p-substituted derivative 0b-16 and m,p-substituted
derivative 0c-16 gave no reflection around 2q = 26o
corresponding to the stacking distance (h) between
Pc disks in the columns, unlike the mesophase of
m-substituted derivative 0a-16. Also, each of the parent
(4:0) compounds {0a~0c-16} gave no Peak H due to the
helical supramolecular structure around 2q = 1.0.
OH-substituted compounds {3a~3c-16}. As shown in
Fig. 9, the X-ray diffraction patterns of three mesophases
in the m-substituted derivative 3a-16 were measured at
room temperature, 130°C and 180°C. Several diffraction
peaks attributable to reflection from the 2D hexagonal
lattice could be observed, commonly in the low angle
region. When the biggest peak in the lowest angle
region was assumed as the (001) reflection from a 2D
hexagonal lattice, all the peaks could be well assigned
as the reflections from the 2D hexagonal lattice. On the
other hand, the peak in the highest angle region could be
assigned as the (001) reflection corresponding to stacking
between Pc disks in the columns. Therefore, all these
three mesophases could be identified as Colho1, Colho2 and
Colho3. As can be seen from Table 4, when the density of
these mesophases Colho1, Colho2 and Colho3 are assumed to
-3
.
be 0.97, 0.95, and 0.90 g cm , respectively, the number
of molecules Z per unit lattice is just 1.0. The Z value is
compatible to a Colho phase [31].
Figure 9 also shows the X-ray diffraction pattern of the
Colho mesophase in the p-substituted derivative 3b-16 at
160°C. As can be seen from the XRD pattern, Peak No. 4
of the (001) reflection corresponding to stacking distance
h in the highest angle region was considerably broader
compared to that of the m-substituted derivative 3b-16.
Also, as can be seen from Table 4, when the density of
-3
.
this mesophase is assumed to be 0.90 g cm , the number
of molecules Z per unit lattice is just 1.0. This Z value is
consistent with the Colho phase [31].
As can also be seen from Fig. 9, the X-ray diffraction
patterns of the mesophases at 100°C and 134°C in the
m,p-substituted derivative 3c-16 gave no (001) reflection
peak corresponding to stacking in the highest angle
region, unlike the m-substituted derivative 3a-16 and
the p-substituted derivative 3b-16. As can be seen from
Table 4, these two mesophases of the m,p-substituted
derivative 3c-16 could be identified as Colhd and Coltet.d,
similarly to the corresponding m,p-substituted parent
(4:0) compound 0c-16.
Furthermore, it is apparent from Fig. 9 that each of the
OH-substituted compounds {3a~3c-16} gave no Peak H
due to the helical supramolecular structure around 2q =
1.0, similarly to the parent (4:0) compounds {0a~0c-16}.
OFBA-substituted compounds {2a~2c-16}. In
Fig. 10 are shown the X-ray diffraction patterns of the
m-substituted derivative 2a-16 at room temperature and
175°C. As can be seen from this figure, each of these two
mesophases gave several diffraction peaks attributable to
reflections from a 2D hexagonal lattice in the low angle
Fig. 7. Illustration of X-ray photographs of Method A: non-
aligned sample; Method B: homogeneously aligned sample;
Method C: homeotropically aligned sample of ordered
columns between two glass plates. In Method A, polydomain
of liquid crystalline phase is filled into a hole. In this case,
the reflections both from 2D and 1D lattices can be observed.
In Method B, homogeneously aligned sample gives the
reflections only from 1D lattice in Z-direction. In Method
C, homeotropically aligned sample gives the reflections
only from 2D lattice in XY plane. If the peak H would be a
periodicity along the Z axis direction of column, the peak H
should disappear for the homeotropically aligned sample in
Method C. Ref. 21
In the same manner, all the other mesophases in the
p-substituted derivative 0b-16 and the m,p-substituted
derivative 0c-16 could be identified as Colhd (for 0b-16),
Colhd and Coltet.d (for 0c-16), respectively.
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 15–23

16
K. ISHIKAWA ET AL.
Table 4. X-ray data of the mesophases in 0a~0c-16, 3a~3c-16, 2a~2c-16 and 1a~1c-16
Compound (mesophase)
Lattice constants/Å
Peak no.
Spacing/Å
Miller indices (h k l)
Observed
Calculated
0a-16: (m-C16OPhO)8PcCu
(Colho at 100°C)
a = 43.2
h = 3.39
Z = 1.0 for r = 1.0
1
2
3
4
5
37.4
21.9
19.0
37.4
21.6
18.7
—
(1 0 0)
(1 1 0)
(2 0 0)
#
ca. 4.7
3.39
3.39
(0 0 1)h
0b-16: (p-C16OPhO)8PcCu
(Colhd at 207°C)
a = 41.5
a = 48.6
1
2
3
35.9
19.7
ca. 5.0
35.9
20.7
—
(1 0 0)
(1 1 0)
#
0c-16: [m,p-(C16O)2PhO]8PcCu
(Colhd at 86°C)
1
2
3
4
42.1
24.3
ca. 9.2
ca. 4.6
42.1
24.0
9.19
—
(1 0 0)
(1 1 0)
(4 1 0)
#
(Coltet.d at 135°C)
a = 34.5
1
2
3
4
34.5
24.7
ca. 9.7
ca. 4.8
34.5
24.4
9.6
(1 1 0)
(2 0 0)
(3 2 0)
#
—
3a-16: (m-C16OPhO)6PcCu-OH
(Colho1 at rt)
a = 40.2
h = 3.44
Z = 1.0 for r = 0.97
1
2
3
4
5
6
7
8
34.8
19.8
17.3
12.9
9.79
8.61
ca. 4.6
3.44
34.8
20.1
17.4
13.2
9.65
8.70
—
(1 0 0)
(1 1 0)
(2 0 0)
(2 1 0)
(3 1 0)
(4 0 0)
#
(0 0 1)h
—
(Colho2 at 130°C)
a = 40.8
h = 3.46
Z = 1.0 for r = 0.95
1
2
3
4
5
6
35.3
20.3
17.5
9.68
ca. 4.8
3.46
35.3
20.4
17.7
9.79
—
(1 0 0)
(1 1 0)
(2 0 0)
(3 1 0)
#
(0 0 1)h
—
(Colho3 at 180°C)
a = 41.0
h = 3.43
Z = 1.0 for r = 0.90
1
2
3
4
5
35.5
20.4
17.6
ca. 4.8
3.43
35.5
20.5
17.7
—
(1 0 0)
(1 1 0)
(2 0 0)
#
(0 0 1)h
—
3b-16: (p-C16OPhO)6PcCu-OH
(Colho at 160°C)
a = 41.5
h = 3.50
Z = 1.0 for r = 0.90
1
2
3
4
35.9
20.2
ca. 4.9
3.50
35.9
20.7
—
(1 0 0)
(1 1 0)
#
—
(0 0 1)h
3c-16: (m,p-C16OPhO)6PcCu-OH
(Colhd at 100°C)
a = 47.2
1
2
3
4
5
6
40.9
23.0
14.9
10.7
8.85
40.9
23.6
15.5
10.2
8.93
—
(1 0 0)
(1 1 0)
(2 1 0)
(4 0 0)
(4 1 0)
#
ca. 4.6
(Continued)
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 16–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
17
Table 4. (Continued)
Compound (mesophase)
Lattice constants/Å
Peak no.
Spacing/Å
Miller indices (h k l)
Observed
Calculated
(Coltet.d at 134°C)
a = 33.2
1
2
3
4
33.2
24.9
9.60
33.2
23.5
9.21
—
(1 0 0)
(1 1 0)
(3 2 0)
#
ca. 4.7
2a-16: (m-C16OPhO)6PcCu-OFBA
(Colho1 at rt)
a = 41.5
h = 3.49
Z = 1.0 for r = 0.95
1
2
3
4
5
6
35.9
20.8
18.2
9.76
ca. 4.7
3.49
35.9
20.7
18.0
9.96
—
(1 0 0)
(1 1 0)
(2 0 0)
(3 1 0)
#
3.49
(0 0 1)h
(Colho2 at 175°C)
a = 44.0
h = 3.47
Z = 1.0 for r = 0.85
1
2
3
4
5
6
7
38.1
21.9
19.3
14.2
9.60
ca. 4.9
3.47
38.1
22.0
19.1
14.4
9.52
—
(1 0 0)
(1 1 0)
(2 0 0)
(2 1 0)
(4 0 0)
#
3.47
(0 0 1)h
2b-16: (p-C16OPhO)6PcCu-OFBA
(Colho at 169°C)
a = 42.5
h = 3.49
Z = 1.0 for r = 0.90
1
2
3
4
5
6
36.8
20.4
17.1
13.3
ca. 4.9
3.49
36.8
21.2
18.4
13.9
—
(1 0 0)
(1 1 0)
(2 0 0)
(2 1 0)
#
(0 0 1)h
3.49
2c-16: [m,p-(C16O)2PhO]6PcCu-OFBA
(Colhd at 120°C)
a = 40.5
1
2
3
4
35.1
19.6
10.2
35.9
20.7
10.1
—
(1 0 0)
(1 1 0)
(2 2 0)
#
ca. 4.8
1a-16: (m-C16OPhO)6PcCu-C60
(Colho at 120°C)
H = 69.2
a = 40.2
h = 3.46
1
2
3
4
5
6
69.0
34.8
19.9
ca. 9.0
ca. 4.7
3.46
—
H
34.8
20.1
8.70
—
(1 0 0)
(1 1 0)
(4 0 0)
#
Z = 1.0 for r = 1.3
3.46
(0 0 1)h
1b-16: (p-C16OPhO)6PcCu-C60
(Colho at 100°C)
a = 40.2
h = 3.37
Z = 1.0 for r = 1.3
1
2
3
4
34.8
19.3
ca. 4.7
3.37
34.8
20.1
—
(1 0 0)
(1 1 0)
#
3.37
(0 0 1)h
1c-16: [m,p-(C16O)2PhO]6PcCu-C60
(Colho at 90°C)
a = 43.6
1
2
3
4
5
80.3
37.8
20.4
10.2
ca. 4.7
—
H
37.8
21.8
10.5
—
(1 0 0)
(1 1 0)
(3 1 0)
#
# = Halo of the molten alkyl chain, h = Stacking distance between the monomers. H = Helical pitch of the fullerences; r: assumed density (g/cm3).
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 17–23

18
K. ISHIKAWA ET AL.
Fig. 8. X-ray diffraction patterns of the parent (4:0) compounds,
0a-16, 0b-16 and 0c-16
Fig. 9. X-ray diffraction patterns of the OH-substituted
compounds, 3a-16, 3b-16 and 3c-16
region. In the highest angle region, a peak corresponding
to the stacking distance in the columns could be also
observed. As can be seen from the corresponding XRD
data in Table 4, these mesophases could be identified as
Colho1 and Colho2. The mesophase of the p-substituted
derivative 2b-16 could be also identified as Colho.
However, as can be seen from Fig. 10, the (001) reflection
(Peak No. 7) corresponding to the stacking distance in the
highest angle region was considerably broader compared
However, as can be seen from Table 4, there was no
contradiction for the assignment to the Colhd phase.
Furthermore, it is apparent from Fig. 10 that each of the
OFBA-substituted compounds {2a~2c-16} gave no Peak
H due to the helical supramolecular structure around 2q =
1.0, similarly to the parent (4:0) compounds {0a~0c-16}
and the OH-substituted compounds {3a~3c-16}.
C60-substituted compounds {1a~1c-16}. As can be
seen from Fig. 11, the X-ray patterns of the m-substituted
(PhO)6PcCu-C60 dyad 1a-16 and the p-substituted
(PhO)6PcCu-C60 dyad 1b-16 were broader and fewer
in number, in comparison with the precursors of the
m-substituted derivative 2a-16 and p-substituted
derivative 2b-16 (in Fig. 10). However, similarly to the
precursors 2a-16 and 2b-16, the (PhO)6PcCu-C60 dyads
1a-16 and 1b-16 gave a (001) reflection in the highest
to the m-substituted derivative 2a-16. When the density
-3
.
of this mesophase is assumed to be 0.90 g cm , the
number of molecules Z per unit lattice is just 1.0. This
Z value is consistent with a Colho phase [31].
Figure 10 also shows the X-ray diffraction pattern of
the mesophase at 120°C in the m,p-substituted derivative
2c-16. As can be seen from this X-ray pattern, the
reflection peaks of the m,p-substituted derivative 2c-16
were broad and smaller in number than the m-substituted
derivative 2a-16 and the p-substituted derivative 2b-16.
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 18–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
19
Fig. 10. X-ray diffraction patterns of the OFBA-substituted
compounds, 2a-16, 2b-16 and 2c-16
Fig. 11. X-ray diffraction patterns of the (PhO)6PcCu-C60
derivatives: 1a-16, 1b-16 and 1c-16
angle region due to the stacking distance (h). On the other
hand, the m,p-substituted 1c-16 gave no (001) reflection
in the highest angle region due to the stacking distance
(h). As can be seen from Table 4, the mesophases of
the m-substituted derivative 1a-16, the p-substituted
derivative 1b-16 and the m,p-substituted derivative 1c-16
could be assigned without contradiction as the Colho,
Colho and Colhd phases, respectively.
Furthermore, as can be seen from Fig. 11, the
m-substituted derivative 1a-16 and the m,p-substituted
derivative 1c-16 showed a very big Peak H (Peak No. 1)
around 2q=1.1 due to the helicalsupramolecular structure,
whereas no Peak H appeared in the p-substituted derivative
1b-16. It is very interesting that Peak H did not appear
only in the p-substituent derivative 1b-16. Therefore,
it is also interesting for us that another research group
reported the helical peak appeared in the p-substituted
(PhO)6PcCu-C60 dyad [= ZnPc-C60] [10, 15, 16, 26].
This p-substituted ZnPc-C60 dyad showed a Peak H
as only a very small shoulder (see Fig. 2(d) in Ref. 16),
whereas our m,p-substituted dyads showed it as an
extremely big clear peak [21, 22, 24, 25]. Moreover, this
PcZn-C60 dyad shows only rectangular columnar (Colr)
phases, so that the dyad cannot achieve homeotropic
alignment. In principle, only hexagonal columnar
(Colh) and tetragonal columnar (Coltet) phases can give
a homeotropically aligned sample [28]. Therefore, it
might be impossible for these Colr phases to prepare the
homeotropically aligned samples for the proof of the
helicity by the X-ray diffraction technique Method C [21].
However, the caption of Fig. S5 of their supplementary
information, says, “XRD patterns of ZnPc-C60 [=
(p-C12OPhO)6PcZn-OPh-C60] films oriented in the
direction of (a) parallel to X-ray beam (solid line) and
(b) perpendicular to the X-ray beam (dashed line) [16]”.
From this expression, it is unknown where the Z-axis
directions in the columns are actually in the samples
(a) and (b): it is also unknown whether these films (a)
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J. Porphyrins Phthalocyanines 2018; 22: 19–23

20
K. ISHIKAWA ET AL.
Terminal Substituent
C60
o = appear; x = disappear
4:0
OH
OFBA
m
0a-16 3a-16 2a-16 1a-16
0b-16 3b-16 2b-16 1b-16
0c-16 3c-16 2c-16 1c-16
x
x
o
x
x
o
x
x
x
x
x
o
p
for Homeotropic alignment
for Stacking distance h
=
=
m,p
o
x
x
o
o
x
o
o
x
o
o
x
x
x
x
x
x
x
x
x
x
o
x
o
for Peak H
=
Fig. 12. Influence of the terminal substituent and the position of the alkoxy group on the appearance of homeotropic alignment,
staking distance h and Peak H
0a-16: (m-C16OPhO)8PcCu;
0b-16: (p-C16OPhO)8PcCu;
3a-16: (m-C16OPhO)6PcCu-OH;
3b-16: (p-C16OPhO)6PcCu-OH;
2a-16: (m-C16OPhO)6PcCu-OFBA;
2b-16: (p-C16OPhO)6PcCu-OFBA;
1a-16: (m-C16OPhO)6PcCu-C60;
1b-16: (p-C16OPhO)6PcCu-C60;
0c-16: [m,p-(C16O)2PhO]8PcCu; 3c-16: [m,p-(C16O)2PhO]6PcCu-OH; 2c-16: [m,p-(C16O)2PhO]6PcCu-OFBA; 1c-16: [m,p-(C16O)2PhO]6PcCu-C60
and (b) are homogeneous and homeotropic, respectively.
Since there is no description about how to prepare these
samples (a) and (b), the other researchers cannot carry
out the replications. If the sample (a) is homogeneously
aligned, the 1D helical peak in the Z-axis direction
should appear but the reflection peaks from the 2D lattice
of the columns in the XY-direction should disappear
(see Method B in Ref. 21). Accordingly, the 2D peak of
(200) should disappear. However, it appears as a large
peak in the XRD in Fig. S5 (a). This is contradictory to
the principle. Also, if the sample (b) is homogeneously
aligned, the1DpeakduetothehelixintheZ-axisdirection
should disappear but the reflection peaks due to the 2D
packing of columns in the XY-direction should appear
(see Method C in Ref. 21). Since the peak assigned to
the helicity in the Z-axis direction disappeared in Fig. S5
(b), the sample (b) should be a homeotropically aligned
sample. However, the evidence of the homeotropic
alignment by using a polarizing microscope was not
written. Therefore, this proof has not satisfactorily carried
out for the helicity of the ZnPc-C60 dyad [10, 15, 16, 26].
Even for the p-substituent dyad ZnPc-C60, they should
first prove the homeotropic alignment by the method
using the polarization microscope, and then the XRD
should be taken for the surely homeotropically-aligned
sample. Moreover, the XRD pattern of a Colr phase
generally gives two strong reflections from the (110) and
(200) planes, because these two planes are the densest in
the molecular net planes. However, the (110) reflection is
absent in this indexation for these Colr phases [16]. From
these scientific viewpoints, this phase identification is not
satisfactory. Therefore, it may be required to reinvestigate
the X-ray structural analysis for the helicity and the
mesophase assignment for the ZnPc-C60 dyad based on
p-substituent (PhO)6PcM-C60 system.
Effect of position of alkoxy group and kind
of terminal substituent on appearance of
homeotropic alignment, stacking h and Peak H
As described above, it was found that the substitution
position of the alkoxy group and the type of terminal
substituent greatly influence the appearance of
homeotropic alignment, stacking h and Peak H.
Therefore, the relationship is summarized in matrix
form in Fig. 12.
As can be seen from these matrixes, the homeotropic
alignment tends to appear only in the m,p-substituted
derivatives, regardless of the terminal substituent.
The stacking distance h tends to appear in the
m-substituted and p-substituted derivatives, but not in
the m,p-substituted derivatives, regardless of the terminal
substituent. On the other hand, Peak H tends to appear
only in the C60-substituted derivatives but not in all the
other derivatives, regardless of the substitution position
of the alkoxy group.
Hereupon, it can be seen from these matrixes that only
the m,p-substituted derivative 1c-16 is a sample suitable
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 20–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
21
C in Fig. 7. The helical peak in the p-substituted
(PhO)6PcCu-C60 dyad [= ZnPc-C60] reported by another
research group [10, 15, 16, 26] should be proven by
Method C for the sample showing both Peak H and
homeotropic alignment.
Reason why Peak H (C60 helix) appears
Figure 14 schematically illustrates
a possible
reason why the helicity of C60 moieties appears in the
m-substituted derivative 1a-16 and the m,p-substituted
derivative 1c-16 but not in the p-substituent derivative
1b-16.
In this figure, the green circle represents the
phthalocyanine (Pc) ring, and both the light blue and
pale yellow circles represent the long chain alkoxy
chains at the m- and p-positions, respectively. In the
m-substituted derivative 1a-16, the long alkoxy chains
may extend downward from the plane of the Pc ring,
because they are substituted at the m-position of the
phenoxy groups whose planes are almost perpendicular
to the Pc ring plane by their steric hindrance. Therefore,
the light blue circle of the long alkoxy chains may be
small as illustrated in this figure. On the other hand,
in the p-substituted derivative 1b-16, the long alkoxy
chains may extend in the same plane as the Pc ring,
because they are substituted at the p-position of the
phenoxy groups. Therefore, the pale yellow circle
of the long alkoxy chains in p-substituted derivative
1b-16 may be much larger than the blue circle of the
m-substituted derivative 1a-16, as illustrated in this
figure. In the m,p-substituted derivative 1c-16, the long
alkoxy chains at the m-position and the p-position may
extend as in the m-substituted derivative 1a-16 and in
p-substituted derivative 1b-16, respectively.
In the m-substituted derivative 1a-16, the hydrophilic
fullerenes (C60s) may be excluded outside the skirt
formed by the hydrophobic long alkoxy chains, so that
the fullerenes can easily aggregate in a helical form.
In the p-substituted derivative 1b-16, the aggregation
of the fullerenes may be thermally disturbed by the
molten long alkoxy chains in the same plane to prevent
formation of helical stacking of fullerenes. On the
other hand, in the m,p-substituted derivative 1c-16, the
fullerenes can be excluded outside the skirt formed
by the long alkoxy chains at the meta position, even
though the long alkoxy chains are substituted also at
the p-position. Thus, a helical aggregation of fullerenes
may also form in the m,p-substituted derivative 1c-16.
It is apparent from our results mentioned above that the
m-substituted long alkoxy chains are needed to form
the helical supramolecular structure of fullerenes in this
type of dyad based on (PhO)6PcM-C60. For more general
compounds, further studies are necessary to prove this
hypothesis.
Fig. 13. Small angle X-ray diffraction patterns of the non-
aligned sample [m,p-(C16O)2PhO]6PcCu-C60 (1c-16) at 90°C.
for Method A and the homeotropically aligned sample between
two glass plates for Method C
for the measurement using Method C in Fig. 7, because
it must be a sample showing Peak H with homeotropic
alignment.
Fig. 13 shows the X-ray patterns of the Colhd
mesophase in the m,p-substituted derivative 1c-16
measured with Method A and Method C. As can be
seen from this figure, when the non-aligned sample
was measured with Method A, both Peak H and (100)
reflection peak could be observed. On the other hand,
when the homeotropically aligned sample was measured
with Method C, the (100) reflection could be observed
but the Peak H disappeared. This means that Peak H is
a periodicity along the Z-axis direction of the column as
illustrated in Fig. 7. Therefore, it could be concluded that
Peak H corresponds to the pitch of C60 stacked spirally
around the column in the Z-axis direction. This is also
supported from previous studies [21, 22, 24, 25]. In our
previous work, a very precise argument was already
described for the homologous derivative 1c-10: [m,p-
(C10O)2PhO]6PcCu-C60. The number of the C60 molecules
per the pitch could be estimated to be about 16 and 23.4°
for the rotation angle of the dyads [21].
Thus, it was proven from the measurements with both
Methods A and C that Peak H in the m,p-substituted
derivative 1c-16 originates from a helical pitch of C60.
As can be seen from the above description, a sample
showing Peak H with homeotropic alignment must be
needed for the helicity proof by using XRD Method
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 21–23

22
K. ISHIKAWA ET AL.
Fig. 14. Possible reason why the helicity of C60 moieties appears for 1a-16 and 1c-16 but not for 1b-16
regardless of the terminal substituents (OH, OFBA and
C60). In addition, the stacking distance h tends to appear
in the m-substituted and p-substituted derivatives, but
not in the m,p-substituted derivatives, regardless of
the terminal substituents (OH, OFBA and C60). On
the other hand, an additional big peak (Peak H) tends
to appear at around 2q = 1.1° in the X-ray diffraction
patterns for the C60-substituted dyads {1a~1c-16} but
not for the other compounds, {0a~0c-16}, {3a~3c-16}
and {2a~2c-16}, regardless of the substitution positions
(m-, p- and m,p-) of the alkoxy group. Moreover, we
revealed that both the m-substituted derivative 1a-16
and the m,p-substituted derivative 1c-16 gave Peak H,
but that only the p-substituted derivative 1b-16 did not
give Peak H among these three dyads {1a~1c-16}. From
the temperature-variable small angle X-ray diffraction
measurements for the m,p-substituted derivative 1c-16
using two different sample preparation methods, we
proved that the Peak H is originated from a helical pitch
of fullerenes. We also pointed out that the m-substituted
long alkoxy chains at least are needed to form the helical
supramolecular structure in the present (PhO)6PcM-C60-
based dyads.
CONCLUSION
In this study, we have synthesized twelve novel
discotic liquid crystals based on a phthalocyaninato
copper(II) complex having the same alkoxy chain of
C16H33O: the parent (4:0) compounds (0a-16, 0b-16,
0c-16), the OH-substituted compounds (3a-16, 3b-16,
03c-16), the OFBA-substituted compounds (2a-16,
2b-16, 2c-16) and the C60-substituted dyads (1a-
16, 1b-16, 1c-16). The letters of a, b and c with the
entry numbers mean the m-substituted derivative,
p-substituted derivative and m,p-substituted derivative,
respectively. The abbreviations of OH, OFBA and C60
indicate the terminal groups of the bridge in the children
(3:1) compound. We have investigated the influence
of both substitution position of the alkoxy chains and
the type of terminal group on the mesomorphism, the
homeotropic alignment, the stacking distance h and the
helical supramolecular structure, by using DSC, POM
and temperature-variable small angle X-ray diffraction
measurements. As a result, each of the derivatives shows
columnar mesophase(s). The homeotropic alignment
tended to appear only in the m,p-substituted derivatives,
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 22–23

DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES 56
23
Soc. 2011; 133: 10736–10739 (submission date:
2011-04-26) published 2011-06-23).
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