DISCOTIC LIQUID CRYSTALS OF TRANSITION METAL COMPLEXES, 55
43
with that of (b-C O) PcCu. Moreover, from the UV-vis
(20 mL) and glacial acetic acid (1 mL) were added and
stirred. The solution turned purple to give precipitations.
After stirring for more 20 min, the resulting purple
crystals were collected by filtration. The crystals
1
8
8
spectra and cyclic voltammograms, it was confirmed that
the LUMO and HOMO levels of 4a–4d were significantly
lowered by 0.37 eV and 0.39 eV, respectively, in
comparison with those of 1a–1d. Thus, we successfully
synthesized phthalocyanine derivatives 4a–4d showing
an absorption band in the near-infrared region and
lower HOMO levels than conventional phthalocyanine
derivatives, according to our expectation.
.
ꢀ
prepared above, Cu(OAc) ꢀ H O (181 mg, 908 mmol)
2
2
and THF (10 mL) were placed in a three-necked flask,
and the mixture was heated with stirring at 50°C for 3 h.
After cooling to rt, the solvent was evaporated under
reduced pressure. The residue was purified by column
chromatography (alumina; chloroform: n-hexane = 2: 1,
Rf = 0.78) to afford dark green crystals (55.1 mg). Yield:
13.8%. Elemental analysis and MALDI-TOF mass data:
See Table 1. UV-Vis spectral data: See Table 2. Phase
transition behavior: See Table 3.
EXPERIMENTAL
Synthesis
2,3-Dichloro-5,6-dicyano-1,4-hydroquinone (Scheme2:
Two series of phthalocyanine copper (PcCu) com-
6). Into a three-necked flask, 2,3-dichloro-5,6-dicyano-p-
benzoquinone (5: 2.50 g, 11.0 mmol) and toluene (30 mL)
were placed and stirred at rt. Subsequently, Na S O (3.38 g,
plexes, (a-C O) PcCu (1a–1d) and (a-C O) (b-Cl) Cu
n
8
n
8
8
(
4a–4d) (n = 6 (a), 8 (b), 10 (c) and 12 (d)) have been
2
2
4
synthesized according to Schemes 1 and 2, respectively.
These synthetic methods were referred to from previ-
ously reported literatures [21, 22, 31–35]. The starting
materials of 2,3-dicyanohydroquinone (2) and 2,3-
dichloro-5,6-dicyano-1,4-hydroquinone (5) were purch-
ased from Tokyo Chemical Industry or Wako Pure
Chemical Industries. All the reactions were carried out
under nitrogen atmosphere. The detailed manners are
described below only for the representative compounds,
19.4 mmol) was added and stirred at rt for 30 min. The
resulted precipitates were collected by suction filtration
and washed with water and n-hexane to afford gray powder
(2.03 g). Yield: 80.6%. IR: (KBr)/cm : 3237, 2253, 1574,
1453, 1360, 1276, 1191, 1075, 887, 776, 746, 689.
-1
4,5-Dichloro-3,6-didecyloxyphthalonitrile (Scheme2:
7c). Into a three-necked flask, 2,3-dichloro-5,6-dicyano-
1,4-hydroquinone (6: 500 mg, 2.18 mmol) and 1-decanol
(1.26 g, 7.96 mmol), triphenylphosphine (1.92 g,
7.32 mmol) and dry THF (20 mL) were placed. The
mixture was stirred at rt. After the reaction vessel was
immersed in an ice bath to cool the solution, a solution of
diisopropyl azodicarboxylate (1.67 g, 8.26 mmol) in dry
THF (10 mL) was added dropwise taking over 30 min.
After completion of the dropping, it was warmed to rt
without the ice bath and stirred at rt for 20 h. When the
solvent was evaporated from the reaction solution under
reduced pressure, a reddish brown viscous liquid was
obtained. When diethyl ether was added to this viscous
liquid, triphenylphosphine oxide was precipitated. The
precipitates were removed by filtration. The filtrate was
evaporated to remove the solvent under reduced pressure.
The residue was purified by column chromatography
(silica gel, chloroform: n-hexane = 2 : 1, Rf = 0.75) and
3
c, 6, 7c, 1c and 4c.
,6-Didecyloxyphthalonitrile (Scheme 1: 3c). Into a
three-necked flask, 2,3-dicyanohydroquinone (2: 600 mg,
.75 mmol), K CO (2.10 g, 15.2 mmol) and DMF
3
3
2
3
(
6 ml) were placed and heated with stirring at 100°C.
After 10 min, 1-bromodecane (2.15 g, 9.74 mmol) was
added and stirred at 100°C for 4 h. The reaction mixture
was cooled down to rt and then extracted with a mixture
solution of ethyl acetate and n-hexane (v/v = 1/1) and
washed with water. The organic layer was dried over
Na SO overnight, filtered, and evaporated the solvents
2
4
under reduced pressure. The residue was purified by
column chromatography (silica gel, dichloromethane,
Rf = 0.83) and then recrystallization from a mixture
solvent of ethyl acetate and n-hexane twice to afford
1
1
.55 g of white crystals. Yield: 93.8%. mp: 141.5°C/lit.
dried in vacuo to give white crystals (855 mg). Yield:
1
1
42°C [36]. H NMR (CDCl , TMS): d [ppm] : 7.15 (2H,
77.1%. mp: 32.0°C. H NMR ((CD ) SO, TMS): d [ppm]:
3
3 2
s, Ar-H), 4.07 (4H, t, J = 6.6 Hz, -OCH ), 1.84 (4H, q, J =
7
4.20 (4H, t, J = 6.6 Hz,-OCH ), 1.79 (4H, q, J = 7.0 Hz,
2
2
.0 Hz, -CH ), 1.50 (4H, q, J = 7.3 Hz, -CH ), 1.18–1.38
-CH ), 1.47 (4H, q, J = 7.2 Hz, -CH ), 1.26–1.35 (24H,
2
2
2
2
(
24H, m, -CH ), 0.91 (6H, t, J = 6.8 Hz, -CH ).
m, -CH ), 0.87 (6H, t, J = 7.0 Hz, -CH ).
2
3
2
3
8
(
a-C O) PcCu(Scheme1:1c). Thereactionsetupwas
(C O) (b-Cl) PcCu (Scheme 1: 4c). Into a three-
1
0
8
10
8
shielded from light. Into a three-necked flask, an excessive
amount of finely chopped lithium was placed and then
C H OH (2.5 mL) was added thereto. The mixture was
necked flask, 4,5-dichloro-3,6-didecyloxyphthalonitrile
(7c: 150 mg, 0.294 mmol), CuCl (25.1 mg, 0.186 mmol)
2
and 1-hexanol (5 mL) were placed and refluxed with
stirring. When the raw materials were completely
dissolved, three drops of DBU were added. After about
10 min, the reaction solution turned green. It was refluxed
for an additional 6 h. After cooling to rt, methanol
was added to the reaction solution to precipitate. The
resulted precipitates were collected by filtration and
10
21
heated and stirred at 100°C. After confirming that the
lithium was dissolved, 3,6-didodecyloxyphthalonitrile
(
1
3c: 400 mg, 908 mmol) was added and heated up to
50°C. Immediately, the reaction solution turned green.
The reaction mixture was held at 150°C for 30 min and
then cooled down to rt. To the reaction solution, acetone
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 43–45