Copper 2,9(10),16(17),23(24)- and 1,8(11),15(18),22(25)-tetra-(4- carboxyphenoxy)phthalocyanines and their esters: The synthesis and liquid-crystalline properties

Article abstract of DOI:10.1007/s11172-006-0372-2

Copper 2,9(10),16(17),23(24)- and 1,8(11),15(18),22(25)-tetra(4- carboxyphenoxy)phthalocyanines and their carboxylic esters were synthesized and their spectral characteristics and liquid-crystalline properties were studied. 2,9(10),16(17),23(24)-Tetrasubs

Full text of DOI:10.1007/s11172-006-0372-2

Russian Chemical Bulletin, International Edition, Vol. 55, No. 6, pp. 1028—1037, June, 2006
1028
Copper 2,9(10),16(17),23(24)ꢀ and 1,8(11),15(18),22(25)ꢀtetraꢀ
(4ꢀcarboxyphenoxy)phthalocyanines and their esters:
the synthesis and liquidꢀcrystalline properties
E. V. Kudrik,aꢀ A. I. Smirnova,b V. E. Maizlish,a T. V. Tararykina,a
G. P. Shaposhnikov,a and N. V. Usol´tsevab
ꢀ
aIvanovo State University of Chemistry and Technology,
7 prosp. F. Engel´sa, 153000 Ivanovo, Russian Federation.
Fax: +7 (093 2) 32 9502. Eꢀmail: ttoc@isuct.ru
bIvanovo State University,
39 ul. Ermaka, 153025 Ivanovo, Russian Federation.
Fax: +7 (093 2) 32 6600. Eꢀmail: usol@ivanovo.ac.ru
Copper 2,9(10),16(17),23(24)ꢀ and 1,8(11),15(18),22(25)ꢀtetra(4ꢀcarboxyphenꢀ
oxy)phthalocyanines and their carboxylic esters were synthesized and their spectral characterꢀ
istics and liquidꢀcrystalline properties were studied. 2,9(10),16(17),23(24)ꢀTetrasubstituted
complexes exhibit both thermotropic and lyotropic mesomorphism in mixtures with a number
of organic solvents.
Key words: phthalocyanines, mesogen, mesophase, lyotropic mesomorphism, amphotropy,
liquid crystals.
Until recently, hydrophobic octasubstituted phthaloꢀ
cyanines were considered as compounds whose liquidꢀ
crystalline properties were best studied. They were menꢀ
tioned in all communications concerned with discotic
mesogens.1 Tetrasubstituted phthalocyanines possessing
amphotropic properties (i.e., both thermotropic and lyoꢀ
tropic mesomorphism) have been much less studied.2—5
Recently, we found that the presence of numerous
lateral substituents in the phthalocyanine molecules is
not a necessary preꢀrequisite for the formation of mesoꢀ
phases. For instance, it was shown that tetraꢀ4ꢀ(nꢀalkoxyꢀ
carbonyl)phthalocyaninatocopper 1 can possess both therꢀ
motropic and lyotropic mesomorphism in binary systems
with organic solvents.6
By varying the length of the aliphatic chain in the
lateral substituent we obtained different types of twoꢀdiꢀ
mensionally ordered textures in the thermotropic state.
By preparing binary systems involving organic solvents we
succeeded to induce a mesomorphic state of nonꢀmesoꢀ
morphic homologs.
Recent studies7 on the liquidꢀcrystalline properties of
various tetrasubstituted phthalocyanine complexes havꢀ
ing bulky substituents revealed that the compounds can
not only possess the mesomorphic properties, but also
form glasses. This makes them promising materials for
practical applications in, e.g., optoelectronics for solar
cell production.
R = COOCnH2n+1 (n = 3, 4, 6, 7, 9—11, 16)
Hexaesters of scilloꢀinositole are the classical discotic
materials having a small central fragment (in contrast to
phthalocyanine derivatives). Taking them as examples,
we showed that introduction of a cyclic fragment8 into
the lateral substituent significantly stabilizes the mesoꢀ
morphic properties compared to similar alkoxycarbonylꢀ
substituted compounds.6
It is noteworthy that the liquidꢀcrystalline properties
of octasubstituted copper phthalocyanine complexes havꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 991—1000, June, 2006.
1066ꢀ5285/06/5506ꢀ1028 © 2006 Springer Science+Business Media, Inc.

Liquidꢀcrystalline phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1029
2: R = H (a), Pr (b), Bu (c), C5H11 (d), iꢀC5H11 (e), C6H13 (f), C7H15 (g), C8H17 (h), C9H19 (i); 3: R = H (a), C5H11 (b)
ing cyclic fragments in lateral substituents have already
been reported.9 The cyclic fragment was introduced into
the lateral substituent of the phthalocyanine molecule in
a target manner in order to obtain singleꢀdomain samples.
Of particular importance was to separate the phenyl fragꢀ
ment and the aliphatic residue by a bridging oxygen
atom,10 because adjacency of these fragments caused a
significant increase in viscosity and thus precluded the
obtaining of singleꢀdomain samples. All these factors were
taken into account in the design and studies of novel
tetrasubstituted phthalocyanine derivatives.
The aim of this work was to synthesize and study the
liquidꢀcrystalline properties and spectroscopic characterisꢀ
tics of novel tetrasubstituted phthalocyanine derivatives
2a—i and 3a,b containing cyclic fragments in the lateral
substituents, namely, two acids (compounds 2a and 3a
(R = H)) and their esters (compounds 2b—i and 3b
(R = CnH2n+1)).
philic substitution of alcohols or phenols for the nitro
group in the 4ꢀnitrophthalodinitrile molecule.15,20,21
This type of phthalocyanines has found applications as
pHꢀsensitive dyes,12 photosensitizers for photodynamic
therapy of cancer,13,14 catalysts for fuel cells and solar
cells,14 and in other fields of science and techꢀ
nology.11,15—19
Carboxyꢀsubstituted phthalocyanines were used as the
starting compounds in the synthesis of corresponding esꢀ
ters that are characterized by high solubility in organic
solvents6,7,22,23 and possess both thermotropic and lyoꢀ
tropic mesomorphism.6,7
Based on the aforesaid, interest in the compounds
combining the properties of aryloxyꢀ and carboxyꢀsubstiꢀ
tuted metal phthalocyanines is quite understandable. We
synthesized a number of tetraꢀ4ꢀ and tetraꢀ3ꢀhydroxyꢀ
phthalocyaninatocopper derivatives starting from 4ꢀ or
3ꢀ(4ꢀcarboxyphenoxy)phthalodinitriles and their derivaꢀ
tives and studied their properties. Copper(II) cation was
chosen to be the complexꢀforming agent because phthaloꢀ
cyaninatocopper(II) derivatives have squareꢀplanar geomꢀ
etries and most of them possess the mesomorphic propꢀ
erties.
Complexes 2 and 3 were synthesized by the interacꢀ
tion of corresponding aryloxyꢀsubstituted phthalodinitriles
with copper acetate at 200 °C (Scheme 1). The starting
4ꢀ or 3ꢀ(4ꢀcarboxyphenoxy)phthalodinitriles 4a and 5a
were obtained by the reaction of 4ꢀ or 3ꢀnitrophthaloꢀ
Results and Discussion
Synthesis. Extensive recent literature11—19 on the synꢀ
thesis and investigation of the properties of various tetraꢀ
4ꢀhydroxyphthalocyanine derivatives including alkoxyꢀ,
aryloxyꢀ, and pyridyloxyꢀsubstituted ones is available.
Such complexes are usually obtained by the interaction of
4ꢀRꢀoxyphthalodinitriles with a corresponding metal salt.
The starting phthalodinitriles can be obtained by nucleoꢀ

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Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
Kudrik et al.
dinitrile with 4ꢀhydroxybenzoic acid in DMF in the presꢀ
ence of potassium carbonate.24 Chloroanhydrides necesꢀ
sary for esterification were synthesized by boiling of 4ꢀ or
3ꢀ(4ꢀcarboxyphenoxy)phthalodinitriles with an excess of
thionyl chloride.
solution. On heating above 190 °C the chloroanhydride
decomposes with liberation of hydrogen chloride. The
3ꢀisomer 5a behaves analogously.
The need of transforming carboxy dinitriles 4a and 5a
to chloroanhydrides is due to the fact that esterification of
carboxylic acids is always a complicated task owing to the
ability of phthalodinitriles to react with alcohols to give
isoindole derivatives under conditions for both acid and
base catalysis. Chloroanhydrides are readily transformed
to esters 4b—i and 5b on heating with an excess of correꢀ
sponding alcohol. Compounds 4b,c,f are lowꢀmelting
white substances; other substituted phthalodinitriles are
waxꢀlike at room temperature. All of them are readily
soluble in organic solvents (CHCl3, CCl4, acetone), beꢀ
ing insoluble in water and aqueous ammonium hydroxide.
Individual character of the substituted phthalodinitriles
was confirmed by elemental analysis and IR spectroꢀ
scopy data.
Scheme 1
The IR spectra of aryloxyphthalodinitriles exhibit
the absorption bands characteristic of CN groups
(2224—2240
cm–1
)
and
aryloxy
groups
(1244—1292 cm–1).25 The carboxyl C=O stretching bands
lie in the range 1695—1705 cm–1 for the carboxy phthaloꢀ
dinitriles 4a and 5a and in the range 1715—1727 cm–1 for
the esters 4b—i.
Compounds 2a and 3a can be dissolved in alkali soluꢀ
tions. Phthalocyanine 2a is only soluble in aqueous amꢀ
monium hydroxide solutions. The 3ꢀisomer 3a can also
be dissolved in aqueous sodium hydroxide solutions. All
the complexes synthesized are soluble in DMF, DMSO,
4: R = H (a), Pr (b), Bu (c), C5H11 (d), iꢀC5H11 (e), C6H13 (f),
C7H15 (g), C8H17 (h), C9H19 (i); 5: R = H (a), C5H11 (b)
Unlike the starting phthalodinitrile 4a, the chloroꢀ
anhydride synthesized in this work is insoluble in dilute
aqueous alkali solutions at room temperature. Dissoluꢀ
tion of the compound occurs only on heating for a few
minutes, which is due to hydrolysis of the compound and
transfer of the corresponding carboxylate thus obtained in
Transmittance (%)
50
40
686.77
30
3057.75
2868.28
743.10
942.82
20
2960.46
10
1501.00
1593.17
1091.32
1270.55
1716.07
3500
Fig. 1. IR spectrum of complex 2b.
3000
2500
2000
1500
1000
ν/cm–1

Liquidꢀcrystalline phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1031
Table 1. Positions of longꢀwavelength absorption bands in elecꢀ
tronic absorption spectra of aryloxyꢀsubstituted copper phthaloꢀ
cyanines 2a—i and 3a,b
and conc. H2SO4; compounds 2b—i and 3b can also be
dissolved in chloroform or benzene.
The IR spectra of the complexes (Fig. 1) exhibit the
absorption bands characteristic of phthalocyanines;26 the
absorption bands corresponding to the functional groups
in the lateral substituents are also observed. The spectra of
tetraꢀ4ꢀ(nꢀalkoxycarbonyl)phthalocyaninatocopper 1 (see
Ref. 6) and complexes 2b—i, 3b are almost identical exꢀ
cept for the absorption bands at 1234—1236 cm–1 in the
spectra of the lastꢀnamed compounds.
High solubility of the newly synthesized compounds
allowed them to be studied by 1H NMR spectroscopy.
The lowꢀfield region of the 1H NMR spectra of comꢀ
plexes 2b—i and 3b exhibits four groups of signals correꢀ
sponding to absorption of the protons bonded to the pheꢀ
nyl ring carbon atoms, the signal positions being almost
independent of the nature of the hydrocarbon radical. As
an example, we will analyze the 1H NMR spectrum of
compound 2g (R = C7H15) (Fig. 2).
The doublet δ 8.15 corresponds to eight phenylene
protons in orthoꢀpositions relative to the COOC7H15 group
while other eight phenylene protons appear as a doublet
at δ 7.30. The signals at δ 7.77, 7.26, and 7.40 can be
attributed to protons in positions 4, 1, and 3 of the
isoindole fragments, respectively. In the highꢀfield reꢀ
gion, the spectra of all the esters synthesized exhibit the
signals of aliphatic radicals. In particular, in the region
δ 0.70—4.30 the spectrum of compound 2g shows the
signals of twentyꢀfour methylene and four methyl proꢀ
tons. Namely, a triplet in the region δ 4.30—4.40 correꢀ
sponds to four αꢀmethylene groups; proton signals of the
βꢀmethylene groups appear as a multiplet in the region
δ 1.70—1.90; the signals of other four methylene groups
and terminal methyl groups appear as multiplets in the
regions δ 1.30—1.60 and 0.75—1.00, respectively. Thus,
as the distance from the electronꢀwithdrawing carbonyl
group increases, the signals of aliphatic protons are shifted
to the lowꢀfield region; this is a characteristic feature of
all alkoxyꢀ and alkoxycarbonylꢀsubstituted compounds.
The NMR spectra of the newly synthesized compounds
2b—i and 3b are more pronounced than those of the
known6 tetraꢀ4ꢀ(nꢀalkoxycarbonyl)phthalocyaninatoꢀ
Comꢀ
pound
R
λmax/nm
DMF
CHCl3
Benzene
2a
2b
2c
2d
2e
2f
2g
2h
2i
H
Pr
Bu
C5H11
iꢀC5H11
C6H13
C7H15
C8H17
C9H19
H
621, 667
—
—
—
—
—
—
—
—
—
612, 679
613, 679
612, 679
612, 679
614, 677
613, 678
612, 678
611, 676
—
612, 648, 678
—
—
—
—
613, 647, 677
613, 647, 677
609, 646, 675
—
—
3a
3b
669, 706
—
C5H11
627, 694
628, 696
copper 1 and exhibit signals of the aromatic protons in the
region δ 7—10 (see Fig. 2). We believe this indicates a
much less pronounced tendency of these complexes to
association. This was confirmed in the analysis of their
electronic absorption spectra.
The electronic absorption spectra of the complexes in
chloroform are typical of metal phthalocyanines. They
exhibit an intense Qꢀband in the region 676—694 nm and
a less intense band at 611—627 nm (vibrational satellite,
Table 1). The character of the spectral curves shows that
the complexes mainly exist in solutions in the monoꢀ
meric form.
Analysis of the electronic absorption spectra of esters
2b—i and 3b suggests that the length and structure of the
alkyl chain have almost no effect on the spectral pattern
and positions of the most important absorption bands
(Fig. 3 and Table 1).
It should be noted that 2,9(10),16(17),23(24)ꢀtetra[(4ꢀ
alkoxycarbonyl)phenoxy]phthalocyaninatocopper comꢀ
pounds 2b—i are less prone to association than tetraꢀ4ꢀ
(nꢀalkoxycarbonyl)phthalocyaninatocopper 1,6 although
the electronic absorption spectra of carboxylic acids 2a
and 3a in DMF indicate the presence of associates in
solutions similarly to the case of tetraꢀ4ꢀphenoxyphthaloꢀ
cyaninatocopper having unsubstituted phenoxy groups.27
The substituent at position 3 of the benzene residues of
the phthalocyanine molecule causes a large bathochromic
shift of the Qꢀband (up to 40 nm) compared to the correꢀ
sponding 4ꢀisomers (see Fig. 3 and Table 1).
Thermotropic mesomorphism. Compounds 2a and 3a
are brittle darkꢀviolet crystals with good adhesion to the
cover glass (probably, they can be electrized with ease).
No melting and thermal decomposition of the samples
occurs on heating of these acids to ~300 °C (upper limit
of observation), i.e., the substances are highꢀmelting
and do not exhibit the liquidꢀcrystalline properties beꢀ
low 300 °C.
8
7
6
5
4
3
2
1
δ
Fig. 2. 1H NMR spectrum of complex 2g.

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Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
A
Kudrik et al.
a
4
3
1
2
b
600
700
λ/nm
Fig. 3. Electronic absorption spectra of complexes 2a (1), 3a (2),
and 2g (3) in DMF and 2i (4) in CCl4.
Ester 3b substituted at nonꢀperipheral position 3 also
does not exhibit mesomorphism.
A study of 2(4),9(10),16(17),23(24)ꢀtetra[(4ꢀalkoxyꢀ
carbonyl)phenoxy]phthalocyaninatocopper compounds
2b—i substituted at peripheral position 4 of the benzene
rings showed that all of them possess liquidꢀcrystalline
properties in the temperature range from ~40 to 280 °C.
The alkyl chain length affects the temperature interval in
which the mesophase exists. At temperatures about 20 °C,
the compounds are in the glassy state, which was conꢀ
firmed by DSC (DSC curves obtained both on heating
and on cooling show no peaks and a kink indicating the
glass transition).
When heated, compounds 2b—i undergo a transition
from the glassy state to the liquidꢀcrystalline state, which
is retained up to a temperature of ~280 °C corresponding
to the onset of thermal decomposition without transition
to the isotropic phase. The absence of crystallization can
probably be explained by the fact that the compounds
under study represent mixtures of four isomers that are
difficult to separate.
The viscous mesophase shown by the homologs 2b—i
is characterized by a nonꢀgeometric texture (Fig. 4, a),
which develops to a herringꢀbone texture (Fig. 4, b) typiꢀ
cal of columnar hexagonal mesophases at high temperaꢀ
tures.
Now we will consider two homologs, 2c (R = Bu) and
2i (R = C9H19) with a short and long aliphatic fragments
in the substituents, respectively, in more detail. Our choice
is due to the fact that earlier we observed a change in the
type of translational ordering of columns in the mesophase
formed by tetraꢀ4ꢀ(nꢀalkoxycarbonyl)phthalocyaninatoꢀ
copper 1 depending on the length of the aliphatic subꢀ
Fig. 4. Textures of columnar hexagonal mesophase observed for
compound 2d in crossed Nicol prisms at 78 (a) and 260 °C (b).
stituent.6 Namely, the homologs with the alkyls C4, C6,
and C7 showed a tetragonally packed columnar mesophase
while the homologs with the alkyls C11 and C16 showed a
hexagonally packed one.
Thermotropic mesomorphism of compound 2c. A polarꢀ
ization microscopy study revealed an anisotropic glassy
state of homolog 2c at room temperature. When heated,
the sample undergoes a gradual transition to the liquidꢀ
crystalline highly viscous phase. At ~60 °C, it is possible
to prepare thinꢀlayer samples and observe a nonꢀgeometꢀ
ric texture typical of columnar hexagonal mesophase. Furꢀ
ther heating causes even greater gradual reduction of visꢀ
cosity, but the texture remains unchanged up to a temꢀ
perature of ~280 °C corresponding to the onset of thermal
decomposition of the compound (according to TGA data).
On cooling the mesophase undergoes a glass transition
with retention of its texture.
The DSC curves obtained both on heating and on
cooling exhibit a kink and one relaxation peak, which is
most pronounced on heating (Fig. 5). This pattern of the
DSC curves indicates that the substance undergoes a glass
transition. The glass transition temperature (Tg) is ~33 °C
on heating and ~29 °C on cooling.
The Xꢀray study of compound 2c was carried out at
two temperatures, 30 and 80 °C, which lie in the temperaꢀ

Liquidꢀcrystalline phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1033
Thermal flux (exo)
chain lateral substituents (the aliphatic chain in the subꢀ
stituent includes only four carbon atoms).
3
Tg ≈ 33 °C
Thus, the results obtained by polarization microscopy,
DSC, and Xꢀray analysis suggest that compound 2c forms
an ordered thermotropic columnar hexagonal mesophase
of the Colho type, which exists in the temperature range
from 33 to ~280 °C. At higher temperatures, thermal deꢀ
composition of the substance occurs without transition to
the isotropic state. On cooling below 29 °C the mesophase
undergoes a glass transition.
0
–3
Thermotropic mesomorphism of compound 2i. Based on
the polarization microscopy data, it is difficult to deterꢀ
mine whether compound 2i is in the mesomorphic or in
the glassy state at room temperature. The substance is
highly viscous and therefore preparation of a uniform thin
layer is a complicated task. However, we can say with
certainty that this is not a crystalline substance. The visꢀ
cosity decreases on heating and at ~65 °C it is possible to
prepare a thinꢀlayer sample, which has a nonꢀgeometric
texture in polarized light.
The DSC curves obtained both on heating and on
cooling in the temperature range from –40 to 280 °C
exhibit only a kink, which proves the existence of the
glassy state at low temperatures and the absence of crysꢀ
tallization. The temperature interval corresponding to glass
transition is rather broad. The glass transition temperaꢀ
ture Tg is ~88 °C on heating and ~58 °C on cooling. No
measurements were carried out above 280 °C because the
TGA data revealed thermal decomposition of the subꢀ
stance.
0
50
100
150
200
T/°C
Fig. 5. DSC curve (third heating cycle) for ester 2c (heating rate
10 deg min–1).
ture ranges of existence of the glassy state and the
mesophase, respectively. Experimental Xꢀray diffraction
patterns obtained at both temperatures are identical, which
also confirms the presence of a glass transition from the
mesophase and the absence of crystallization. The Xꢀray
diffraction patterns (Fig. 6) show clearly seen 100, 110
and 200 reflections characterized by a Bragg distance raꢀ
tio of 1 : 1/30.5 : 1/2, which is typical of columnar hexagoꢀ
nal mesophase. The calculated hexagonal lattice constant
a equals 24.75 and 24.87 Å at 30 and 80 °C, respectively.
Additionally, both Xꢀray diffraction patterns show a clearly
seen reflection in the largeꢀangle region (d = 3.3 Å),
which indicates an ordered arrangement of the molecules
in columns.
Usually, Xꢀray diffraction patterns of discotic comꢀ
pounds with aliphatic lateral substituents exhibit a broad
halo characteristic of "molten" disordered arrangement of
hydrocarbon chains. In the Xꢀray diffraction pattern of
compound 2c the halo is weak and has a maximum in the
range 10 < θ < 11° (i.e., d = 4—4.5 Å). Probably, low
intensity of this maximum is due to the presence of shortꢀ
An Xꢀray study was carried out at room temperature
and at 65 and 110 °C. Raising the temperature causes an
increase in the intensities of the smallꢀangle reflections
and peaks become more pronounced (Fig. 7). For inꢀ
stance, only one signal (100) is observed at room temꢀ
perature, whereas at 65 °C we also observed the 110 and
200 reflections. This is particularly pronounced at 110 °C,
namely, a fourth reflection (210) is added to the three
reflections (100, 110, and 200) . It should be noted that the
positions of the reflections are almost independent of temꢀ
perature. According to calculations, the ratio of the Bragg
I/count s–1
800
600
400
200
100
distances for the signals observed is 1 : 1/30.5 : 1/2 : 1/70.5
,
being typical of the columnar hexagonal mesophase. The
hexagonal lattice constant a is 30.35 Å. As for comꢀ
pound 2c (R = Bu), at all temperatures the Xꢀray diffracꢀ
tion patterns of homolog 2i (R = C9H19) show a signal in
largeꢀangle region (d ≈ 3.4 Å), which indicates an ordered
type of the columnar hexagonal mesophase. A broad halo
(d ≈ 4.7 Å) is more pronounced compared to that obꢀ
served for homolog 2c. This is probably due to longer
aliphatic fragments in lateral substituents.
d = 3.33 Å
110 200
Thus, our Xꢀray study of complexes 2c (R = Bu) and
2i (R = C9H19) showed that they form highly ordered
columnar hexagonal mesophases with intermolecular disꢀ
tance in columns 3.3—3.4 Å.
2
4
6
8
10
12
θ/deg
Fig. 6. XꢀRay diffraction pattern of nonꢀoriented sample of comꢀ
pound 2c at 80 °C.

1034
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
Kudrik et al.
I/count s–1
1000
a
100
3
2
a
800
600
400
200
1
110
200
1
2
3
θ/deg
I/count s–1
b
70
60
b
110
50
3
200
40
30
20
10
2
210
1
d = 3.34—3.39 Å
Fig. 8. Textures observed in contact preparation of binary sysꢀ
tem 2a—DMSO at room temperature (after cooling): mosaic
texture, nuclei of Schlieren textures, isotrope (upward) (a) and
the Schlieren texture (b). Crossed Nicol prisms, ×250.
4
6
8
10
12
θ/deg
Fig. 7. XꢀRay diffraction pattern of nonꢀoriented sample of comꢀ
pound 2i in the region of the first reflection 100 (smallꢀangle
region) (a) and in the region of other reflections and in the
largeꢀangle region (b): T = 25 (1), 65 (2), and 110 °C (3).
lutions, but also in polar organic solvents, such as DMSO
and DMF. Thus, hydrophobic "bridges" (oxyphenylene
groups) in complex 2a undoubtedly make a large contriꢀ
bution to intermolecular interactions, which manifests
itself as a tendency to association and affects the microꢀ
segregation of this complex.
Lyotropic mesomorphism. A study of binary composiꢀ
tions formed by nonꢀmesomorphic compounds 3a,b subꢀ
stituted at nonꢀperipheral position 3 with such solvents
as cyclohexane, chloroform, benzene, cyclohexanone,
DMSO, DMF, water, and aqueous NaOH (pH 12) and
NH4OH (pH 11) solutions showed that none of these
systems possesses lyotropic mesomorphism.
At the same time nonꢀmesomorphic acid 2a substiꢀ
tuted at peripheral position 4 in binary systems with
DMSO, DMF, and aqueous ammonia solution at room
temperature forms two types of lyomesophases: 1) mesoꢀ
phase with nonꢀgeometric or soapꢀlike texture, which
transforms to a mosaic texture on cooling (Fig. 8, a) and
2) mesophase with spherolites and Schlieren texture
(Fig. 8, b), which is more viscous than conventional nemꢀ
atic mesophase. Based on the textures observed and on
the viscosities of the lyomesophases formed, we can sugꢀ
gest that the former phase can have a columnar twoꢀ
dimensionally ordered structure and the latter can have a
nematic or lamellar columnar structure.
Among esters 2b—i, lyotropic mesomorphism studies
were carried out for compounds 2c—e. We found that
they possess lyotropic polymesomorphism with various
organic solvents. The temperature range of existence of
the lyomesophase depends on the degree of saturation of
chemical bonds in the cyclic solvents. For instance, comꢀ
pounds 2c—e are readily soluble in mixtures with unsatꢀ
urated cyclic hydrocarbons (benzene or cyclohexene) and
chloroform and show three types of lyomesophases in the
contact preparations at room temperature. One lyoꢀ
mesophase has a texture similar to that observed in the
thermotropic state (Fig. 9, a). The other two lyomesoꢀ
phases are probably nematic ones, being characterized by
the Schlieren and cloud textures (Fig. 9, b). These two
types of textures were observed in our previous studies of
lyotropic compositions of macrocyclic tetranuclear metal
complexes29 and octasubstituted phthalocyanines.30
Mixtures of homologs 2c—e with cyclic saturated
hydrocarbons (cyclohexane, cyclooctane, or cyclodecane)
It should be noted that unlike tetraꢀ4ꢀcarboxyphthaloꢀ
cyaninatocopper,6b,28 complex 2a is prone to lyomesoꢀ
morphism not only in aqueous ammonium hydroxide soꢀ

Liquidꢀcrystalline phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1035
Although the tendency to association of compounds
in solutions is a prerequisite for the formation of lyotropic
mesophases in these systems, it is not a key factor. Inꢀ
deed, some compounds possessing this property do not
show lyomesomorphism, while complexes 2a—i present
in solutions mainly as monomers showed a mesophase.
Our study of mesomorphism in the homologous series
2b—i revealed that they can form both thermotropic and
lyotropic mesophases (amphotropy). The amphotropic
properties of these compounds depend on the length of
the lateral substituents.
a
Thus, we synthesized and characterized novel repreꢀ
sentatives of tetrasubstituted copper phthalocyanines,
namely, compounds 2 and 3 containing phenyl fragments
in the substituents. We showed the effects of the substituꢀ
tion site (peripheral/nonꢀperipheral) in the benzene fragꢀ
ments of the phthalocyanine molecules and of the strucꢀ
ture of the lateral substituent on the liquidꢀcrystalline
properties. Phthalocyanines containing OC6H4COOH
fragments at peripheral positions of the benzene rings
(e.g., compound 2a) do not form thermotropic mesophases
(as in the case of simple replacement of four carboxyl
groups6b); however, two types of lyotropic mesophases
can be formed in the binary systems including 2a and
DMSO, DMF, or aqueous ammonia solution. Further
modification of the lateral substituents by esterification of
carboxy groups causes compounds 2b—i not only to form
an ordered thermotropic columnar hexagonal mesophase
Colho, but also to exhibit lyotropic mesomorphism in mixꢀ
tures with organic solvents. This type of substituents in
nonꢀperipheral positions of the benzene rings in the
phthalocyanine molecules causes suppression of the meꢀ
somorphic (both thermotropic and lyotropic) properties
of tetraꢀ3ꢀ(4ꢀcarboxyphenoxy)phthalocyaninatocopper 3a
and the corresponding ester 3b. Unlike tetraꢀ4ꢀ(nꢀalkoxyꢀ
carbonyl)phthalocyaninatocopper 1,6 compounds 2b—i
can undergo a glass transition, which creates prerequisites
for the use of these compounds in optoelectronics.
b
Fig. 9. Photomicrographs of lyotropic systems 2d—organic solꢀ
vent (crossed Nicol prisms, magnification ×250): nucleation of
twoꢀdimensionally ordered columnar mesophase on cooling from
the isotrope to 2d—CHCl3 contact preparation, T = 23 °C (a)
and two types of nematic phases (Schlieren texture is shown
below and a cloud texture is shown above) in the contact prepaꢀ
ration 2d—cyclohexene at room temperature (b).
form the same lyomesophases, but this occurs at higher
temperatures.
It is important that a study of the contact preparations
of compounds 2c—e with linear alkanes (from pentane
to pentadecane) revealed no formation of new mesoꢀ
phases, except for the twoꢀdimensionally ordered columꢀ
nar phase, which existed in the thermotropic state. Thereꢀ
fore, mixing of phthalocyanines 2c—e with linear satuꢀ
rated hydrocarbons is only accompanied by the swelling
due to penetration of the solvent into peripheral regions
of supramolecular columnar ensembles. In other words,
in this case linear alkanes do not induce lyotropic mesoꢀ
morphism in contrast to the previously studied series of
tetraꢀ4ꢀ(nꢀalkoxycarbonyl)phthalocyanines 1 whose mixꢀ
tures with linear hydrocarbons form a nematic lyoꢀ
mesophase.6
Based on the aforesaid, we can conclude that simultaꢀ
neous presence of a bridging oxyphenylene fragment and
the ester or carboxyl groups in the phthalocyanine molꢀ
ecule makes a tendency of these compounds to form highly
ordered lyomesophases more pronounced and the specꢀ
trum of the lyomesophases becomes much broader.
Experimental
The phase state of individual compounds and phthalocyaꢀ
nine—solvent binary systems were studied by the classical methꢀ
ods of investigation of liquid crystals including polarization miꢀ
croscopy, DSC, and Xꢀray analysis.
The phase state of the samples was studied with a Leitz
Laborlux 12 Pol polarization microscope equipped with a Mettler
FP 82 heating stage and a Wild MPS 51 photograph accessory
(24×36 mm2). Lyotropic mesomorphism was studied by the conꢀ
tact preparations method. The second components of the binary
systems studied were linear alkanes from pentane to pentadecane,
as well as cyclohexane, cyclooctane, cyclodecane, cyclohexene,
and chloroform (Merck and Aldrich). These compounds are
traditionally used as solvents in studies of hydrophobic discotic
mesogens.

1036
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
Kudrik et al.
DSC experiments were carried out on a Perkin Elmer DSC 7
instrument at a heating rate of 10 deg min–1
Table 2. Yields and elemental analysis data for phthalodinitriꢀ
les 4b—i
.
XꢀRay study was carried out on a Huber Guinierꢀgoniomꢀ
eter 600 instrument equipped with a Huber 611 quarz monoꢀ
chromator, a Huber HTC 9000 stepping motor controller, and a
Huber 9634 temperature controller, with a standard resolution
of 0.01°, acquisition time of 20 s per 1 step. A tube with a
Cu cathode (λ = 1.54051 Å) was used for generation of Xꢀray
radiation.
Comꢀ
poꢀ
und
R
Yield
(%)
Found
Calculated
Molecular
formula
(%)
N
C
H
4b
4c
4d
4e
4f
Pr
67
69
69
70.50 4.80 9.09
70.58 4.61 9.15
70.99 5.04 8.68
71.24 5.03 8.74
71.80 5.50 8.35
71.84 5.43 8.38
71.81 5.51 8.35
71.84 5.43 8.38
72.36 6.00 8.02
72.40 5.79 8.04
72.73 6.14 7.66
72.91 6.12 7.73
73.35 6.50 7.45
73.38 6.43 7.44
73.81 7.00 7.15
73.82 6.71 7.17
C18H14N2O3
C19H16N2O3
C20H18N2O3
C20H18N2O3
C21H20N2O3
C22H22N2O3
C23H24N2O3
C24H26N2O3
Electronic absorption spectra were recorded on a Perkin
Elmer Lambda 200 UV/VIS spectrophotometer. IR spectra were
Bu
1
obtained with an IRꢀBeckmann 9 instrument. H NMR spectra
C5H11
were recorded on a Bruker AC 250 spectrometer (250 MHz) in
CDCl3 solutions with Me4Si as a reference.
iꢀC5H11 57
Synthesis of (carboxyphenoxy)phthalodinitriles 4a and 5a
(general procedure). To DMSO (60 mL), 4ꢀ or 3ꢀnitrophthaloꢀ
dinitrile (1.73 g, 0.01 mol), 4ꢀhydroxybenzoic acid (2.07 g,
0.015 mol), and freshly calcined potassium carbonate (4.14 g,
0.03 mol) were added at 20—25 °C. The mixture was stirred for
6 h at 100 °C, cooled, the solution thus obtained was poured into
a fourfold amount of water, filtered, the filtrate was acidified by
hydrochloric acid solution, the precipitate was washed with waꢀ
ter until neutral pH value and recrystallized from water.
4ꢀ(4ꢀCarboxyphenoxy)phthalodinitrile (4a). Yield 1.2 g (45%).
IR (KBr), ν/cm–1: 2232 (C≡N); 1290, 1252 (Ar—O—Ar); 1695
(COOH). Found (%): N, 10.80. C15H8N2O3. Calculated (%):
N, 10.60.
3ꢀ(4ꢀCarboxyphenoxy)phthalodinitrile (5a). Yield 1.1 g (42%).
IR (KBr), ν/cm–1: 2232 (C≡N); 1290, 1252 (Ar—O—Ar); 1705
(COOH). Found (%): N, 10.40. C15H8N2O3. Calculated (%):
N, 10.60.
4ꢀ(Dicyanophenoxy)benzoyl chlorides were synthesized folꢀ
lowing a known procedure24 by the interaction of compounds 4a
or 5a (2.64 g, 0.01 mol) with boiling thionyl chloride (50 mL)
with continuous stirring for 20 h. Excess thionyl chloride was
removed by evaporation at ~20 °C and the residue was dried
in vacuo at 50 °C.
4ꢀ(3,4ꢀDicyanophenoxy)benzoyl chloride, yield 2.5 g (84%).
Found (%): Cl, 11.75; N, 9.43. C15H7ClN2O3. Calculated (%):
Cl, 11.87; N, 9.38.
4ꢀ(2,3ꢀDicyanophenoxy)benzoyl chloride, yield 2.42 g (81%).
Found (%): Cl, 11.76; N, 9.43. C15H7ClN2O3. Calculated (%):
Cl, 11.87; N, 9.38.
Synthesis of phthalodinitriles 4b—i and 5b (general proceꢀ
dure). Chloroanhydride of compound 4a or 5a (0.3 g, 0.001 mol)
and corresponding preliminarily dehydrated alcohol (10 mL)
were boiled with continuous stirring until HCl liberation ceased
(~1.5—2 h). Then the excess of alcohol was removed in vacuo
and the reaction products were dried. The yields and elemental
analysis data are listed in Table 2.
Synthesis of substituted copper phthalocyanines 2a—i and 3a
(general procedure). A thoroughly ground mixture of correspondꢀ
ing substituted phthalodinitrile (0.015 mol) and copper(II) acꢀ
etate hydrate (0.76 g, 0.004 mol) was heated at 200 °C with
stirring for 20—30 min. The melt was thoroughly ground, washed
with 10% hydrochloric acid and water until neutral pH value,
and dried.
C6H13
C7H15
C8H17
C9H19
63
66
64
64
4g
4h
4i
Table 3. Yields and elemental analysis data for tetrasubstituted
copper phthalocyanines 2a—i and 3a,b
Comꢀ
poꢀ
und
R
Yield
(%)
Found
Calculated
Molecular
formula
(%)
N
C
H
2a
2b
2c
2d
2e
2f
H
45
46
66
61
64.60 3.00 9.97 C60H32CuN8O12
64.32 2.88 10.00
67.08 4.45 8.66 C72H56CuN8O12
67.10 4.38 8.69
68.00 5.00 8.24 C76H64CuN8O12
67.87 4.80 8.33
68.48 5.24 8.01 C80H72CuN8O12
68.58 5.18 8.00
68.42 5.24 7.98 C80H72CuN8O12
68.58 5.18 8.00
69.16 5.70 7.58 C84H80CuN8O12
69.24 5.53 7.69
70.02 6.00 7.35 C88H88CuN8O12
69.85 5.86 7.40
70.38 6.24 7.10 C92H96CuN8O12
70.41 6.17 7.14
Pr
Bu
C5H11
iꢀC5H11 56
C6H13
C7H15
C8H17
C9H19
H
54
53
57
59
42
47
2g
2h
2i
70.61 6.56 7.00 C96H104CuN8O12
70.94 6.45 6.89
64.59 3.00 9.80 C60H32CuN8O12
64.32 2.88 10.00
68.49 5.23 7.80 C80H72CuN8O12
68.58 5.18 8.00
3a
3b
C5H11
Complexes 2a and 3a were dissolved in 3% hydroxide amꢀ
monium, filtered, the solution was acidified with dilute hydroꢀ
chloric acid, the precipitate was washed with water until neutral
pH value of the rinse water and the absence of chloride ions in
the filtrate, and then reprecipitated from concentrated sulfuꢀ
ric acid.
Compounds 2b—i and 3b were preꢀextracted with chloroꢀ
form or benzene and purified by chromatography on alumina

Liquidꢀcrystalline phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 6, June, 2006
1037
with a benzene—chloroform (1 : 1) mixture as eluent. The solꢀ
vent was removed in vacuo. All complexes were dried in vacuo at
140—170 °C. The yields and elemental analysis data are listed in
Table 3.
9. K. Hatsusaka, K. Ota, I. Yamamoto, and H. Shirai, J. Mater.
Chem., 2001, 11, 423.
10. K. Kawata, M. Negoro, H. Nishikawa, and M. Okazaki,
Ekisho, 1998, 1, 45.
Unlike other compounds, complex 3b was obtained without
isolation of phthalodinitrile. The interaction of 4ꢀ(2,3ꢀdiꢀ
cyanophenoxy)benzoyl chloride with pentanꢀ1ꢀol was followed
by immediate addition of copper acetate to the solution and the
reaction mixture was kept at 195—200 °C.
11. P. Gregory, J. Porphyrins Phthalocyanines, 2000, 4, 432.
12. K. Ogawa, S.ꢀI. Kinoshito, and H. Nakahara, Chem. Lett.,
1990, 11, 2025.
13. A. F. Mironov, Fotodinamicheskaya terapiya raka [Photodyꢀ
namic Therapy of Cancer], in Uspekhi khimii porfirinov
[Adv. Porphyrin Chemistry], Ed. O. A. Golubchikov, Izd.
NII Khimii at SaintꢀPetersburg State University, St.ꢀPetersꢀ
burg, 1997, 1, 357 (in Russian).
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Kostromina, S. V. Volkov, and L. M. Yagupolskii, J. Porphyꢀ
rins Phthalocyanines, 1997, 1, 341.
17. M. Kimura, Y. Yamaguchi, T. Koyama, K. Hanahusa, and
H. Shirai, J. Porphyrins Phthalocyanines, 1997, 1, 309.
18. S. Gunter, A. K. Sobbi, W. Spiller, H. Kliesch, and
D. Wohrle, J. Porphyrins Phthalocyanines, 1997, 1, 159.
19. C. C. Leznoff, A. M. D´Ascano, and S. Z. Yildiz, J. Porphyꢀ
rins Phthalocyanines, 2000, 4, 103.
20. Patent Application 61ꢀ207365 (Japan); R. Zh. Khim. ["Chemꢀ
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21. J. G. Young and W. Onyebuagu, J. Org. Chem., 1990,
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The authors express their gratitude to D. W. Bruce
(University of York, United Kingdom) and to
G. Lattermann and L. Torre Lorente (Bayreuth Univerꢀ
sity, Germany) for providing access to NMR, DSC, and
Xꢀray analysis facilities.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 04ꢀ03ꢀ32305)
and the Ministry of Education and Science of the Russian
Federation ("Development of Scientific Potential of the
Higher School", Program No. 2.2.1.1.7280).
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Received June 10, 2005;
in revised form April 12, 2006