Phthalonitriles containing ester groups and copper phthalocyanines based on them

Article abstract of DOI:10.1134/S1070363211040268

Phthalonitriles containing ester groups were obtained by acylation of 4-hydroxyphthalonitrile and esterification of 4-(p-carboxyphenyloxy) phthalonitriles. On the basis of these phthalonitriles the respective copper phthalocyanines were synthesized. Spectral and some other physical and chemical properties of the synthesized compounds were investigated.

Full text of DOI:10.1134/S1070363211040268

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 4, pp. 768–772. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © T.V. Tikhomirova, V.E. Maizlish, G.P. Shaposhnikov, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81, No. 4, pp. 678–
682.
Phthalonitriles Containing Ester Groups
and Copper Phthalocyanines Based on Them
T. V. Tikhomirova, V. E. Maizlish, and G. P. Shaposhnikov
Ivanovo State Chemical Engineering University, pr. F. Engelsa 7, Ivanovo, 153000 Russia
e-mail: ttoc@isuct.ru
Received April 22, 2010
Abstract—Phthalonitriles containing ester groups were obtained by acylation of 4-hydroxyphthalonitrile and
esterification of 4-(p-carboxyphenyloxy)phthalonitriles. On the basis of these phthalonitriles the respective
copper phthalocyanines were synthesized. Spectral and some other physical and chemical properties of the
synthesized compounds were investigated.
DOI: 10.1134/S1070363211040268
Complexes of phthalocyanines with metals (MPc)
have valuable practical properties and can be used in
various fields of science and technology. Each specific
field of application requires well-defined properties
that can be added to MPc by chemical modification.
Phthalocyanines containing ether groups and well
soluble in organic solvents are of definite interest.
Already there is an evidence on the possibility of their
practical use [1–4]. However, the information con-
cerning the metal phthalocyanines containing ester
groups is rather poor, although we believe that they
can possess other valuable properties besides the
solubility in organic solvents.
In this paper the synthesis and properties of
substituted phthalonitriles containing ester groups and
copper phthalocyanines based on them are considered.
Initial phthalonitriles were synthesized by two
procedures.
By the first procedure, 4-nitrophthalonitrile (I) was
transformed into a 4-hydroxyphthalonitrile (II) by the
reaction of nucleophilic substitution [5]. Then the
nitrile II was O-acylated in pyridine medium. As acyla-
tion agents substituted benzoic acid chlorides were
used obtained by the interaction of respective acid with
an excess of thionyl chloride. Thus a series of R-
benzoyloxyphthalonitriles (IIIa–IIIi) was prepared [6].
NC
NC
NO2
NC
NC
OH
NaNO2, K2CO3, DMF, H+
I
II
R
C
O
Cl, Py
NC
O
C
R
O
NC
IIIа−IIIi
R = OC3H7 (a), OC5H11 (b), OC7H15 (c), OC8H17 (d), OC9H19 (e), OC11H23 (f),
O
C
O
C11H23 (g), O
C
O
C7H15 (h), O
C
O
OC8H17 (i).
768

PHTHALONITRILES CONTAINING ESTER GROUPS
769
SO2Cl
NC
NC
O
C
O
OH
NC
NC
O
C
O
Cl
IV
V
NC
NC
O
C
O
OR
ROH
VIa_VIf
R = C3H7 (a), C4H9 (b), C5H11 (c), C7H15 (d), C8H17 (e), C9H19 (f).
The optimized conditions of the acylation process
found by applying mathematical modeling are as
follows: the molar ratio of reagents 1:1, temperature 84
to 85°C, and the reaction time 17 h [7]. For the isola-
tion of target compounds from the reaction mixtures
we used the difference in the solubility in organic sol-
vents of the original substances and the products
obtained. To confirm individuality of the phthalo-
nitriles we used the method of chromato-mass spec-
trometry [6].
residue, and in the weakest field the signals of protons
of the phthalonitrile fragment were present [6].
In the IR spectra of the synthesized phthalonitriles
the absorption bands were observed characteristic of
phthalonitriles [10]. In the region of 2232–2240 cm–1
the spectra of all compounds contain absorption bands
corresponding to vibrations of the nitrile group, and in
the range of 1670–1750 cm–1 the absorption bands
appear characteristic of vibrations of the ester C=O
bonds. In the spectra of (p-alkoxycarbonylphenoxy)
phthalonitriles VIa–VIf in the region of 1244–
1292 cm–1 absorption appears due to the presence of
aryloxy groups [11].
The (p-alkoxycarbonylphenoxy)phthalonitriles VIa–
VIf were obtained by the second procedure. Initial 4-
(p-carboxyphenyloxy)phthalonitrile (IV) was syn-
thesized by the reaction of 4-nitrophthalonitrile with p-
hydroxybenzoic acid in DMF medium in the presence
of potassium carbonate [8]. Then 4-(p-carboxy-
phenyloxy)phthalonitrile (IV) was refluxed with an
excess of thionyl chloride to obtain the corresponding
chloride (V) and the latter was subjected to
esterification. After the reaction completion, an excess
of the alcohol used for the esterification was distilled
off in a vacuum [9].
On the basis of the synthesized phthalonitriles
respective copper phthalocyanines VIIa–VIIo were
synthesized by the “nitrile” method.
The synthesized compounds are powders of blue-
green color whose physical and chemical properties
are largely determined by the nature of functional
substituents. The presence in their composition of ester
groups with different alkyl chains imparts them with
the solubility in organic solvents (chloroform, benzene,
DMF). This allowed us to apply column chromato-
graphy on alumina for their purification.
All synthesized phthalonitriles are powders (IIIa–
IIIf, VIc–VIf) or waxy substances (IIIg–IIIi, VIc–VIf)
of white to cream color. All compounds are readily
soluble in organic solvents (chloroform, acetone) and
insoluble in water and aqueous alkaline solutions.
In the IR spectra of the complexes the absorption
bands were detected in the regions of 1612–1624,
1505–1524, 1342–1360, 1246–1288, 1170–1188,
1140–1150, 1116–1130, 1080–1092, 1048–1060, 910–
950, 850–880, 770–780, and 734–736 cm–1, charac-
teristic of phthalocyanines [12]. Besides, the spectra
contained the absorption bands corresponding to the
functional substituents.
The structure of the phthalonitriles obtained was
1
confirmed by 1H NMR and IR spectroscopy. In the H
NMR spectra of the synthesized nitriles in deutero-
chloroform the signals of protons of alkoxy substituent
were observed in the strong field. The signals posi-
tions do not depend on the nature of the hydrocarbon
radical. In a weak field the signals occurred of the
protons of benzene ring of the substituted benzoic acid
The 1H NMR spectra of the obtained complexes are
similar in nature and contain the signals of aliphatic
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 4 2011

770
TIKHOMIROVA et al.
O
C
R1
R
N
N
N
Cu
N
R1
NC
NC
R
C
O
R1
R
C
O
Cu(OAc)2 2H2O
R1
N
C
O
R
N
N
N
R1
C
O
R
VIIa_VIIo
R = O, R1 = C6H4OC3H7 (a), C6H4OC5H11 (b), C6H4OC7H15 (c), C6H4OC8H17 (d), C6H4OC9H19 (e), C6H4OC11H23 (f),
C6H4OCOC11H23 (g), C6H4OCOC6H4C7H15 (h), C6H4OCOC6H4OC8H17 (i); R = O
R1 = C3H7 (j), C4H9 (k), C5H11 (l), C7H15 (m), C8H17 (n), C9H19 (o).
,
protons in the strong field and aromatic protons in the
weak field [6, 9].
there is an intense weight loss of the samples.
Analyzing the IR spectra of the samples after heating
to 350°C and comparing them with the IR spectra of
starting material we note a significant decrease in the
intensity of the absorption bands characterizing
vibrations of the functional substituents (C=O, C–H,
etc.). The samples heated in this temperature range
became practically insoluble in organic solvents.
However, the EAS of the solutions in DMF have the
form typical for metallophthalocyanines. These data
suggest that the process of thermal degradation is
associated with the changes in the substituents. The
thermooxidative degradation of tetra-4-(p-alkoxycar-
bonylphenoxy)copper phthalocyanines VIIj–VIIo with
the removal of ester groups occurs at temperatures
around 280°C [9], in contrast to the complexes VIIa–
VIIi for which this process takes place at 180°C.
In the 1H NMR spectra of the synthesized
compounds a downfield shift of the signals of aliphatic
protons can be noted upon increase in their distance
from the electron-acceptor carbonyl group, due to the
rapid decrease in the negative inductive effect of the
carboxy oxygen of the ester groups [13].
Thermal stability. Investigation of stability of the
complexes VIIa–VIIo toward the thermo-oxidative
degradation showed a similarity in their behavior. In
the first phase upon heating in air to 175°C the TG
curves registered a slight decrease in the mass of the
samples. The additional examination by the IR and
electron absorption spectroscopy (EAS) of the phthalo-
cyanine samples before the DTA experiment and after
heating to 180°C showed their identity. This observa-
tion suggests that the changes in the derivatograms do
not relate to the processes of destruction of the MPc.
At further heating the decomposition of compounds
becomes complicated, as evidences the presence of
several maxima in the DTA and DTG curves.
At further heating (above 350°C) thermal oxidative
destruction of the phthalocyanine macrocycle occurs to
the formation of copper oxides. In general it is noted
that the studied phthalocyanines are much less stable
thermally than the copper phthalocyanines without
substituents.
Analysis of the TG leads to the following
assumptions. At heating from 180°C to 300–350°C
The electron absorption spectra of all complexes
in organic solvents contain two absorption bands in the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 4 2011

PHTHALONITRILES CONTAINING ESTER GROUPS
Сharacteristics of electron absorption spectra of phthalocyanines
771
λmax, nm (D/Dmax
)
Comp. no.
R1
DMF
CHCl3
H7C3OH4C6
H11C5OH4C6
H15C7OH4C6
H17C8OH4C6
H19C9OH4C6
H23C11OH4C6
H23C11OCOH4C6
H15C7H4C6OCOH4C6
H18C8OH4C6OCOH4C6
H7C3O
671 (1.00), 610 (0.63)
670 (1.00), 615 (0.74)
671 (1.00), 671 (0.75)
670 (1.00), 617 (0.75)
671 (1.00), 615 (0.72)
670 (1.00), 612 (0.75)
672 (1.00), 611 (0.45)
670 (1.00), 618 (0.84)
670 (1.00) 615 (0.86)
678 (1.00), 614 (0.72)
678 (1.00), 615 (0.74)
679 (1.00), 614 (0.70)
678 (1.00) 615 (0.72)
678 (1.00), 615 (0.74)
678 (1.00), 615 (0.70)
673 (1.00), 610 (0.75)
673 (1.00) 613, (0.76)
673 (1.00), 611 (0.79)
672 (1.00), 611 (0.77)
672 (1.00), 614 (0.76)
672 (1.00), 617 (0.80)
672 (1.00), 616 (0.51)
672 (1.00), 614 (0.96)
672 (1.00), 617 (0.93)
679 (1.00), 612 (0.75)
679 (1.00), 613 (0.78)
679 (1.00), 612 (0.80)
679 (1.00), 613 (0.87)
679 (1.00), 612 (0.85)
665 (1.00), 611 (0.86)
VIIа
VIIb
VIIc
VIId
VIIe
VIIf
VIIg
VIIh
VIIi
VIIj
VIIk
VIIl
H9C4O
H11C5O
H15C7O
VIIm
VIIn
VIIIo
H17C8O
H19C9O
region of 600–700 nm, with the intensity ratio
depending on the concentration of phthalocyanine in
the solution (see the table and the figure). Upon
dilution the intensity of the longwave band decreases
to a lesser extent, than the shortwave band. This
phenomenon and the observed changes in the intensity
ratio of the absorption bands indicate a tendency of the
metallocomplexes to association in solutions. In
addition, the association is confirmed by the
temperature dependence of the intensity ratio of the
absorption bands and by the deviation from the
Bouguer–Lambert–Beer law at the concentrations
above 10–7 mol l–1 as well.
monomer–dimer equilibrium with the dimerization of
the π–π type [16].
The position of the longwave band in the electron
absorption spectra depends on the location of the ester
group. When it is far from the macrocyle, the
absorption occurs at longer wavelength (see the table).
For all the synthesized complexes we observed that
the solvent nature does not affect the position of the
absorption bands (see the figure).
D
2.0
1
Proceeding from the structure of the synthesized
complexes and the published data [14, 15], we can
assume that in the solutions may form dimers, both due
to hydrogen bonding between the peripheral sub-
stituents in the phthalocyanine molecules, and owing
to π–π interactions.
1.5
2
3
1.0
0.5
0
By an example of tetra-4-[(4'-heptyloxybezoyl)oxy]
copper phthalocyanine (VIIa) we studied the processes
of association of such complexes in benzene, o-xylene,
and chloroform by the methods of calorimetric dilution
and electron absorption spectroscopy. In the benzene,
chloroform and o-xylene solutions at the concentration
of the complex from 5×10–6 to 7×10–5 M there is a
400
500
600
700
800
λ, nm
Electron absorption spectra of compound VIIc in various
solvents at the concentration 5×10–5 M: (1) o-xylene,
(2) benzene, and (3) chloroform.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 4 2011

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TIKHOMIROVA et al.
3. Tsaryova, O., Semioshkin, A., Wöhrle, D., and Bre-
The liquid crystal properties. Study of the
gadze, V.I., J. Porphyrins Phthalocyanines, 2005, vol. 9,
no. 3, pp. 268–274.
synthesized complexes using polarization microscopy
revealed that they all exhibit thermotropic mesomor-
phism [9, 17, 18]. Comparing the data obtained for the
tetra-4-[(p-alkoxycarbonyl)phenoxy]copper (VIIj–VIIo),
and tetra-4-[(R-benzoyl)oxy]copper phthalocyanines
(VIIa–VIIi) that differ from each other by the location
of ester group, we can draw the following conclusions:
(1) The increase in the number of carbon atoms in the
alkyl chain decreases the phase transition temperatures
of the complexes of both types, but the melting points
of tetra-4-[(p-alkoxycarbonyl)phenoxy]copper phthalo-
cyanines (VIIj–VIIo) with n > 7 begin to grow, that is
not observed for the compounds VIIa–VIIi. (2) At
more distant location of the ester group from the
macrocycle the temperature of transition of the
phthalocyanines into the mesomorphic state raises.
4. Komori, T. and Amao, Y., J. Porphyrins
Phthalocyanines, 2002, vol. 6, no. 3, pp. 211–216.
5. Ustinov, V.D., Plakhtinskii, V.V., Mironov, T.S., and
Ryabukhina, N.S., Zh. Org. Khim., 1979, vol. 15, p. 1775.
6. Tararykina, T.V., Maizlish, V.E., Galanin, N.E.,
Shaposhnikov, G.P., Bykova, V.V., and Usol’tseva, N.V.,
Zh. Org. Khim., 2007, vol. 43, no. 11, pp. 1718–1724.
7. Tararykina, T.V. Rozhkov, S.V., Maizlish, V.E., So-
lon, B.Ya., and Shaposhnikov, G.P., Izv. Vuzov, Ser.
Khim. i Khim. Tekhnolog., 2007, vol. 50, no. 7, pp. 95–97.
8. Hirth, A., Sobbi, F.R., and Wohrle, D., J. Porphyrins
Phthalocyanines, 1997, vol. 1, no. 3, pp. 275–279.
9. Kudrik, E.V., Smirnova, A.I., Maizlish, V.E., Tarary-
kina, T.V., Shaposhnikov, G.P., and Usol’tseva, N.V.,
Izv. Akad. Nauk, Ser. Khim., 2006, no. 6, pp. 991–1000.
10. Rodionov, G.N., Boglaenkova, G.V., Mikhalenko, S.A.,
It is also important to note that compounds VIIh
and VIIi and the copper tetra-4-[(p-alkoxycarbonyl)-
phenoxy]phthalocyanines VIIj–VIIo are capable of
vitrification with preservation of the mesophase texture
that makes them promising for application in opto-
electronics [2] .
and Luk’yanets, E.A., Khimiya
promezhutochnykh produktov i krasitelei, tekstil’no-
vspomogatel’nykh veshchestv drugikh produktov
i
tekhnologiya
i
organicheskogo sinteza (Chemistry and Technology of
the Intermediates and Dyes, the Textile-Auxiliary
Materials and Other Products of Organic Synthesis),
Moscow: NIITEKhIM, 1974, pp. 3–11.
The tendency of compounds to the associative
processes is a prerequisite for the formation by such
substances of a liomesophase [2]. To test this assump-
tion, we carried out a study of several synthesized cop-
per complexes [9, 17, 18].
11. Daier, D.R., Applications of Absorption Spectroscopy of
Organic Compounds, Moscow: Khimiya, 1970.
12. The Porphyrin Handbook, Kadish, K., Smith K.,
Guilard, R., and Kadish, K.M., Eds., Elsevier (USA),
2003, vol. 16.
We found that among the tetra-4-[(R-benzoyl)oxy]
copper phthalocyanines VIIa–VIIi only the complexes
that include alkoxy groups (VIIa–VIIf, VIIi) form
liomesophase in a binary system with organic solvent.
It should also be noted that these complexes can show
the mesomorphism only with low-polarity and non-
polar solvents (chloroform, benzene). In contrast to these
compounds, copper tetra-4-[(p-alkoxycarbonyl)phenoxy]-
phthalocyanines VIIj–VIIo are capable to form
liomesophase in binary systems with a wider range of
organic solvents (chloroform, benzene, DMF, etc.).
13. Smirnova, A.I., Maizlish, V.E., Usol’tseva, N.V.,
Bykova, V.V., Anan’eva, G.A., Kudrik, E.V., Shiro-
kov, A.V., and Shaposhnikov, G.P., Izv. Akad. Nauk,
Ser. Khim., 2000, no. 1, pp. 129–136.
14. Monohan, A.R., Brado, J.A., and DeLuca, A.F., J. Phys.
Chem., 1972, vol. 76, no. 3, pp. 446–449.
15. Lebedeva, N.Sh., Pavlycheva, N.A., Petrova, O.V., and
Parfenyuk, E.V., J. Porphyrins Phthalocyanines, 2005,
vol. 9, no. 3, pp. 240–247.
16. Vashurin, A.S., V’yugin, A.I., Lebedeva, N.Sh.,
Maizlish, V.E., Tararykina, T.V. and Shaposhnikov, G.P.,
Izv. Vuzov, Ser. Khim. i Khim. Tekhnol., 2009, vol. 52,
no. 8, pp. 46–50.
The synthesized phthalocyanines are well soluble in
organic solvents and can be used as a fat-soluble dyes
for dyeing waxes, hydrocarbons, plastics, and rubber [19].
17. Tararykina, T.V., Maizlish, V.E., Shaposhnikov, G.P.,
Zharnikova, N.V., Bykova, V.V., and Usol’tseva, N.V.,
Zhidkie Kristally i Ikh Prakticheskoe Ispol’zovanie,
2005, nos. 3–4 (13–14), pp. 21–27.
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