Metal phthalocyanines with undecyloxybenzoic acid residues, and their mesomorphic properties

Article abstract of DOI:10.1023/B:RUGC.0000025520.29732.9e

Acylation of 4-amino-5-nitro-, 5-amino-4-bromo-, 5-amino-4-phenoxy-, 4-hydroxy-5-nitro-, 3-and 4-hydroxyphtalonitriles with p-undecyloxybenzoyl chloride gave the corresponding acyl derivatives which were used to prepare copper and cobalt phthalocyanines.

Full text of DOI:10.1023/B:RUGC.0000025520.29732.9e

Russian Journal of General Chemistry, Vol. 74, No. 2, 2004, pp. 295 299. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 2, 2004,
pp. 329 333.
Original Russian Text Copyright
2004 by Balakirev, Maizlish, Balakireva, Shaposhnikov, Bykova, Usol’tseva.
Metal Phthalocyanines with Undecyloxybenzoic Acid Residues,
and Their Mesomorphic Properties
A. E. Balakirev, V. E. Maizlish, O. V. Balakireva,
G. P. Shaposhnikov, V. V. Bykova, and N. V. Usol’tseva
Ivanovo State University, Ivanovo, Russia
Received March 1, 2002
Abstract Acylation of 4-amino-5-nitro-, 5-amino-4-bromo-, 5-amino-4-phenoxy-, 4-hydroxy-5-nitro-, 3-
and 4-hydroxyphtalonitriles with p-undecyloxybenzoyl chloride gave the corresponding acyl derivatives which
were used to prepare copper and cobalt phthalocyanines. Physicochemical properties of the resulting products
were studied. The synthesized metal complexes all exhibit mesomorphic properties.
The present work is a continuation of our sys-
NC
NC
NH2 ClOC
+
X
tematic studies on the synthesis and properties of
novel substituted phthalocyanines (Pc) [1 5] and is
concerned with phthalocyanine complexes containing
undecyloxybenzoic acid residues.
OC11H23
I
II
NHCOC6H4OC11H23
NC
NC
X
The synthesis and properties of tetra-4-acyloxy-
tetra-5-nitro-, tetra-4-acylaminotetra-5-nitro-, tetra-5-
acylaminotetra-4-bromo-, and tetra-5-acylaminotetra-
4-phenoxyphthalocyanines have been reported [5 8].
As shown, peripheral acetyl, benzoyl, and capriloyl
substituents fail to impart to the phthalocyanine
molecule solubility in ordinary organic solvents, such
as benzene, chloroform, and carbon tetrachlolide.
III
X = NO2 (I), Br (II), OC6H5 (III).
The products were identified by their elemental
analyses and IR spectra. The IR spectra of compounds
I III preserve a series of absorption bands typical of
phthalonitriles and their derivaties [10], including the
band at 2232 cm due to nitrile vibrations [ (CN)].
In addition, in the range 1720 1688 cm , absorption
1
1
Using as the acylating agent the mesomorphic p-un-
decyloxybenzoyl chloride [9], we prepared copper and
cobalt tetra-4-(4-undecyloxybenzoylamino)tetra-5-
nitro-, tetra-4-bromotetra-5-(4-undecyloxybenzoyl-
amino)-, and tetra-4-phenoxytetra-5-(4-undecyloxy-
benzoylamino)phthalocyanines, as well as copper
tetra-4-(4-undecyloxybenzoyl)tetra-5-nitro-, tetra-4-(4-
undecyloxybenzoyloxy)-, and tetra-3-(4-undecyloxy-
benzoyloxy)phthalocyanines. The resulting complexes
are soluble in benzene, chloroform, carbon tetra-
chloride, and other organic solvents.
bands characteristic of acylamino keto groups
[ (C=O)] are observed, as well as a band at 1664 cm ,
1
providing evidence for the presence of secondary
amino groups [ (NH)]. At the same time, the band at
1
1636 cm corresponding to vibrations of the free
amino group disappears. Methyl and methylene ab-
sorption bands [ (CH3), (CH2)] are observed at
1
2920 2848 cm , and Ar O Ar absorption appears at
1
1256 cm [10].
The spectrum of nitrile I contains bands typical of
asymmetric [ as(NO2)] and symmetric [ (NO2)]
stretching vibrations of the nitro group (154s4 1536
1
and 1368 1352 cm , respectively).
The starting N-acyl-substituted phthalonitriles I III
were prepared by the reaction of the corresponding
amines with p-undecyloxybenzoyl chloride at 150 C
for 1.5 h by the following scheme.
By fusing phthalontriles I III with metal salts at
190 200 C for 1h we obtained metal complexes
IV IX.
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296
BALAKIREV et al.
H23C11OC6H4OCHN
X
N
NHCOC6H4OC11H23
X
N
N
MLn
I III
M
N
N
N
N
X
H23C11OC6H4OCHN
N
NHCOC6H4OC11H23
X
X = NO2 (IV, V), Br (VI, VII), OC6H5 (VIII, IX); M = Cu (IV, VI, VIII), Co (V, VII, IX).
O-Acylated copper phthalocyanines X XII were
prepared directly from acyloxyphthalonitriles without
their isolation. The scheme of the synthesis of com-
plex X is given below.
NC
NC
OCOC6H4OC11H23
NO2
NC
NC
OH
ClOC
+
OC11H23
NO2
H23C11OC6H4OCO
O2N
NO2
N
OCOC6H4OC11H23
N
N
M
N
N
N
N
NO2
H23C11OC6H4OCO
N
OCOC6H4OC11H23
O2N
Acyl-substituted phthalocyanines are dark blue and
dark green powdery substances. They are soluble in
benzene, chloroform, acetone, DMF (except for
IV VII), and concentrated sulfuric acid.
The long-wave absorption band in the spectrum of
complex IV is slightly (by 4 nm) shifted bathochro-
mically with respect to that in the spectrum of com-
plex X. The same pattern was observed earlier with
copper 4-acyloxytetra-5-nitrophthalocyanines and was
explained by the higher electronegativity of oxygen
compared with nitrogen [6]. It must be also noted that
compounds X XII are less prone to association in
DMF than in other organic solvents, as evidenced by
the electronic absorption spectra. In the long-wave
region of the spectrum, there is a single strong
absorption band (Fig. 1).
The UV absorption spectra of the obtained metal
phthalocyanines in chloroform contain two broadened
absorption bands at 620 645 and 672 705 nm (see
table), which are evidence for the association of the
compounds in this solvent by hydrogen bonding
between the bulky acylamino (acyloxy) groups. The
same pattern is observed in benzene.
As would be expected, the change from amino-
(hydroxy)-substituted phthalocyanines to the corres-
ponding acylamino(acyloxy) derivatives produces a
hypsochromic shift of the long-wave absorption band,
on account of the lower donor power of the latter
groups compared with amino or hydroxy groups.
It is known that mesomorphic phthalocyanine de-
rivatives offer promise for optoelectronics and other
fields of science and technology. To evaluate the
practical utility of the synthesized compounds, we
examined their mesomorphic properties.
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METAL PHTHALOCYANINES WITH UNDECYLOXYBENZOIC ACID RESIDUES
297
Yields, positions of the first bands in the electronic absorption spectra, and elemental analyses of phthalocyanines IV XII
Electronic absorption
spectrum, max, nm
Found, %
H
Calculated, %
Comp.
no.
Yield,
%
Formula
chloroform
H2SO4
C
N
C
H
N
IV
V
33
37
37
36
35
33
34
32
36
629, 700
628, 695
630, 705
634, 695
635, 688
634, 678
678
725
725
752, 774
772
65.1
65.2
60.8
61.0
73.4
73.6
65.3
72.2
72.3
6.5
6.4
5.8
5.8
6.5
6.4
6.2
7.1
7.1
11.4 C104H120CuN16O16
11.9 C104H120CoN16O16
8.4 C104H120Br4CuN12O8 61.0 5.9
8.3 C104H120Br4CoN12O8 61.1 5.9
8.3 C128H140CuN12O12
8.4 C128H140CoN12O12
9.0 C104H116CuN12O20
6.4 C104H120CuN8O12
6.6 C104H120CuN8O12
65.3 6.3 11.7
65.4 6.3 11.7
VI
VII
VIII
IX
X
8.2
8.2
8.0
8.0
8.8
6.5
6.5
817
794
73.1 6.7
73.3 6.7
65.1 6.1
71.9 7.0
71.9 7.0
XI
XII
701
620, 676
It was earlier shown that certain tetrasubstituted
phthalocyanines and their metal derivatives exhibit
lyotropic properties but do not possess thermotropic
mesomorphism [11 13]. It was also found that nitro
substitution ortho to substituents that are already
present in these complexes denudes their of mesomor-
phic properties. In this connection it was of interest
to evaluate the ability of our synthesized metal com-
plexes to form mesophases.
mesomorphism in binary systems with toluene or
chloroform; therewith, the lyotropic mesophase, like
with the nitro-containing analogs, is also formed
already at room temperature.
Copper tetra-4phenoxytetra-5-(4-undecyloxyben-
zoylamino)phthalocyanine (VIII) forms a thermotropic
mesophase when heated from 85 to 111 C. Its cobalt
complex IX shows thermotropic monotropic meso-
morphism only, forming a mesomorphic phase at 86
65 C. Compounds VIII and IX possess no lyotropic
mesomorphism.
According to polarizing microscopy data, copper
and cobalt tetra-4-bromotetra-5-(4-undecyloxyben-
zoylamino)- (VI, VII), tetra-4-(4-undecyloxybenzoyl-
amino)tetra-5-nitro- (IV, V), and tetra-4-phenoxytetra-
5-(4-undecyloxybenzoylamino)phthalocyanines (VIII,
IX), as well as copper tetra-4-(4-undecyloxybenzoyl-
oxy)tetra-5-nitro- (X), tetra-3-(4-undecyloxybenzoyl-
oxy)- (XI), and tetra-4-(4-undecyloxybenzoyloxy)-
phthalocyanine (XII) possess mesomorphic properties.
A
Copper tetra-4-(4-undecyloxybenzoylamino)tetra-
5-nitrophthalocyanine (IV) forms an enantiotropic
thermotropic phase when heated from 125 to 205 C,
and a lyotropic mesophase in binary systems with
chloroform or toluene at room temperature (Fig. 2).
Unlike the copper complex, cobalt tetra-4-(4-unde-
cyloxybenzoylamino)tetra-5-nitrophthalocyanine (V)
exhibits no thermotropic mesomorphism, but it forms
a lyotropic mesophase in binary systems with chloro-
form or toluene.
1
3
2
550
650
750
, nm
Copper and cobalt tetra-4-bromotetra-5-(4-unde-
cyloxybenzoylamino)phthalocyanines
(VI,
VII)
possess thermotropic monotropic mesomorphism,
forming a mesophase at 60 and 100 C, respectively,
which is preserved upon cooling to room temperature
and then crystallizes. These complexes show lyotropic
Fig. 1. Electronic absorption spectra (1) of copper tetra-
4-(4-undecyloxybenzoyloxy)phthalocyanine (XII) in
DMF and of copper tetra-3-(4-undecyloxybenzoyloxy)-
phthalocyanine (XI) in (2) DMF and (3) chloroform.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 2 2004

298
BALAKIREV et al.
amphotropic, which is rather uncommon for discotic
mesogens [11].
EXPERIMENTAL
The electronic absorption spectra were taken in
chloroform and benzene solutions on a Specord M-40
spectrophotometer at room temperature at 500
900 nm.
Thermotropic mesomorphism was studied by
means of polarizing thermomicroscopy on an MIN-8
1
microscope with a hot stage, heating rate 2 deg min .
Lyotropic mesomorphism was studied by the contact-
ing samples techniques.
Phtalonitriles I III (general procedure). A mix-
ture of 0.1 g of amine and 0.2 g of p-undecyloxy-
benzoyl chloride was heated to 150 C and left to s
tand for 1.5 h. After this time, the reaction mixture
was diluted with 5 ml of 10% aqueous sodium car-
bonate. The precipitate was filtered off, washed with
water to neutral washings, dried at 60 C, and re-
crystallized from benzene.
The reaction products are powdery yellow sub-
stances insoluble in water and soluble in acetone,
chloroform, and DMF.
Fig. 2. Photomicrograph of the texture of copper tetra-4-
(4-undecyloxybenzoylamino)tetra-5-nitrophthalocyanine
(IV) in chloroform. Crossed polarizers, 250.
5-Nitro-4-(4-undecyloxybenzoylamino)phtalo-
nitrile (I). Yield 0.15 g (63%), mp 96 98 C. IR spec-
1
trum, , cm : 2920-2896 [ (CH3, CH2)]; 2232
Copper tetra-4-(4-undecyloxybenzoyloxy)tetra-5-
nitrophthalocyanine (X) is mesomorphic when heated
from 66 to 100 C.
[ (CN)]; 1720 1688 [ (C=O)]; 1664 [ (NH)]; 1544
[
as(NO2)]; 1344 [ (NO2)]. Found, %: C 67.3; H 6.3;
s
N 12.3. C26H30N4O4. Calculated, %: C 67.5; H 6.5;
N 12.1.
Copper tetra-3-(4-undecyloxybenzoyloxy)- and
tetra-4-[(4-undecyloxybenzoyloxy)phthalocyanines
(XI, XII) form a pillar-type thermotropic mesophase
when heated from 41 to 80 C and from 85 to 111 C,
respectively. These compounds possess no lyotropic
mesomorphism.
4-Bromo-5-(4-undecyloxybenzoylamino)phtalo-
nitrle (II). Yield 0.16 g (71%), mp 80 82 C. IR spec-
1
trum, , cm : 2920 2896 [ (CH3, CH2)]; 2232
[ (CN)]; 1720 1688 [ (C=O)]; 1664 [ (NH)]. Found,
%: C 63.0; H 5.9; Br 16.3; N 8.2. C26H30BrN3O2.
Calculated, %: C 62.9; H 6.1; Br 16.1; N 8.5.
The resulting data show that compounds IV XII
exhibit a pillar-type supramolecular packing in the
mesophase. However, the molecular structure is
crucial for thermal stability of the mesophases. The
thermal stability of the copper complexes decreases in
the following order: IV > VIII > VI.
4-Phenoxy-5-(4-undecyloxybenzoylamino)-
phtalonitrile (III). Yield 0.14 g (65%), mp 88 90 C.
1
IR spectrum, , cm : 2920-2896 [ (CH3, CH2)]; 2232
[ (CN)]; 1720 1688 [ (C=O)]; 1664 [ (NH)]; 1256
(Ar O Ar). Found, %: C 75.7; H 6.6; N 8.1. C32H35
N3O3. Calculated, %: C 75.4; H 6.9; N 8.35.
Comparison of the complexes CuPc(4-COC6H4O
C11H23)4 (XI) and CuPc(3-OCOC6H4OC11H23)4 (XII),
which differ from each other in the positions of the
substituents, provides evidence for our earlier con-
clusion that 4-substituents in the benzene rings of
phthalocyanines favor stronger mesomorphic pro-
perties of the corresponding derivatives, and, in the
case in hand, thermally more stable mesophases.
Phthalocyanines IV IX (general procedure). Ni-
trile I III, 2.5 mmol, and 0.7 mmol of metal salt were
fused in a sealed ampule for 1 h at 190 200 C. The
resulting fusion cake was ground, washed succes-
sively with 3% HCl to colorless filtrates, water to
remove chloride ions, and 5% aqueous sodium car-
bonate and water to neutral washings. Further puri-
fication was carried out by means of column chro-
It is significant that complexes IV, VI, and VII are
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METAL PHTHALOCYANINES WITH UNDECYLOXYBENZOIC ACID RESIDUES
299
matography (eluent chloroform, sorbent Silica gel
L 40/100).
4. Shishkina, O.V., Cand. Sci. (Chem.) Dissertation,
Ivanovo, 2000.
5. Balakirev, A.E., Cand. Sci. (Chem.) Dissertation,
Ivanovo, 2001, p. 17.
Phthalocyanines X XII (general procedure). p-
Undecyloxyoxybenzoyl chloride, 1.1 mmol, was
added to 1 mmol of hydroxy-substituted phthalonitrile,
and the reaction mixture was vigorously stirred for 2 h
at 80 85 C until HCl no longer evolved. The tem-
perature was slowly brought to 150 C, 0.3 mmol of
copper acetate was added, and the mixture was heated
for 1.5 h at 180 185 C. The target product was
washed with 3% HCl and water to neutral washings.
Further purification was carried out by means of
column chromatography (eluent chloroform, sorbent
Silica gel L 40/100).
6. Balakirev, A.E., Maizlish, V.E., Shaposhnikov, G.P.,
and Smirnov, R.P., Abstracts of Papers, II Mezhdu-
narodnaya nauchno-tekhnicheskaya konferentsiya
Aktual’nye problemy khimii i khimicheskoi tekhno-
logii (Khimiya-99) (Int. Conf. Actual Problems of
Chemistry and Chemical Technology (Chemistry-99) ,
Ivanovo, 1999, p. 109.
7. Balakirev, A.E., Maizlish, V.E., Shaposhnikov, G.P.,
and Smirnov, R.P., Zh. Obshch. Khim., 2000, vol. 70,
no. 4, p. 669.
8. Maizlish, V.E., Balakirev, A.E., Shaposhnikov, G.P.,
and Smirnov, R.P., Zh. Obshch. Khim., 2001, vol. 71,
no. 2, p. 274.
The elemental analyses, yields of the target com-
pounds, and positions of the Q band in the electronic
absorption spectra are given in the table.
9. Demus, D. and Zaschke, H., Flussige Kristalle in
Tabellen II, Leipzig: Grundstoffindustrie, 1984,
p. 420.
ACKNOWLEDGMENTS
10. Nahanishi, K., Infrared Absorption Spectroscopy.
Practical, San Francisco: Holden Day, 1962.
Translated under the title Infrakrasny’ye spectry i
stroeniye organicheskikh soedinenii, Moscow: Mir,
1965, p. 216.
The present study was financially supported by the
Universities of Russia Basic Research Program
(project no. 4007).
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