Synthesis and properties of tetraanthraquinonyl- and tetraanthraquinonyloxy-substituted copper and cobalt phthalocyanines

Article abstract of DOI:10.1134/S1070363216050170

Cobalt and copper tetra-[4-(9,10-dioxo-9,10-dihydroanthraceny-2-yl)]- and tetra-{4-[(9,10-dioxo-9,10-dihydroanthracen-2-yl)oxy]}phthalocyanines have been prepared; their spectral properties have been studied.

Full text of DOI:10.1134/S1070363216050170

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 5, pp. 1084–1090. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © E.A. Gureeva, A.V. Borisov, G.P. Shaposhnikov, 2016, published in Zhurnal Obshchei Khimii, 2016, Vol. 86, No. 5, pp. 822–828.
Synthesis and Properties of Tetraanthraquinonyl-
and Tetraanthraquinonyloxy-Substituted Copper
and Cobalt Phthalocyanines
E. A. Gureeva, A. V. Borisov*, and G. P. Shaposhnikov
Scientific-Research Institute of Chemistry of Macroheterocyclic Compounds,
Ivanovo State University of Chemistry and Technology, pr. Sheremetevskii 7, Ivanovo, 153000 Russia
*e-mail: ttos@isuct.ru
Received June 1, 2015
Abstract—Cobalt and copper tetra-[4-(9,10-dioxo-9,10-dihydroanthraceny-2-yl)]- and tetra-{4-[(9,10-dioxo-
9,10-dihydroanthracen-2-yl)oxy]}phthalocyanines have been prepared; their spectral properties have been studied.
Keywords: metal phthalocyanine, anthraquinone, biphenyl-3,4-dicarboxylic acid, electronic absorption spectrum,
IR spectrum, acylation, cyclization
DOI: 10.1134/S1070363216050170
Peripheral functionalization of the macrocycle is
among the best studied approaches towards chemical
modification of phthalocyanines (Pc). A variety of com-
pounds exhibiting wide range of physico-chemical
properties have been prepared via substitution of hyd-
r-gen atoms of the benzene ring [1]. The derivatives
bearing aryl and aryloxy substituents in the benzene
cycles have been recognized as practically important
phthalocyanines. The arylated phthalocyanines can be
used as pigments with enhanced stability against
alkaline hydrolysis [2]. The aryloxy-substituted phthalo-
cyanines have been studied as liquid crystals [3, 4],
photosensibilizers for photodynamic cancer therapy
[5], thin-film materials for electronography and
microelectronics [6], etc. In view of this, development
of methods of preparation of such compounds is a
topical issue.
This work extends the studies of chemistry of anthra-
quinonyl- and anthraquinonyloxy-substituted phthalo-
cyanines. They belong to the class of tetraanthraquino-
neporphyrazines, scarcely discussed in the literature
[6–11]. In particular, we report the preparation of
copper and cobalt tetra-[4-(9,10-dioxo-9,10-dihydro-
anthracen-2-yl)]- and tetra-{4-[(9,10-dioxo-9,10-dihyd-
roanthracen-2-yl)-oxy]}phthalocyanines via template
synthesis and optical properties of the products.
Firstly, we synthesized the required precursors: 4-
(9,10-dioxo-9,10-dihydroanthracen-2-yl)phthalic acid
1, 4-[(9,10-dioxo-9,10-dihydroanthracen-2-yl)oxy]phthalic
acid 2, and 4-[(9,10-dioxo-9,10-dihydroanthracen-2-yl)-
oxy]phthalonitrile 3. Synthesis of those compounds
has not been earlier described in the literature
(Scheme 1).
Scheme 1.
O
O
O
COOH
O
R
R
O
COOH
2, 3
1
R = COOH (2), CN (3).
1084

SYNTHESIS AND PROPERTIES OF TETRAANTHRAQUINONYL-
1085
Scheme 2.
O
C6H14, AlCl3,
O
O
O
H2SO4
O
R
R
R
COOH
O
3, 10, 11
4−6
7−9
O
O
R =
(4, 7, 10),
(5, 8, 11),
(3, 6, 9).
CN
COOEt
COOEt
CN
COOEt
COOEt
Compounds 1–3 were obtained via acylation of
diethyl esters of biphenyl-3,4-dicarboxylic acid, 4-
phenoxyphthalic acid, and 4-phenoxyphthalonitrile,
respectively. Direct acylation of biphenyl-3,4-
dicarboxylic or 4-phenoxyphthalic acids did not occur,
likely due to the influence of the carboxylic groups
reducing the electronic density at carbon atoms of the
unsubstituted phenyl cycle. On top of that, the starting
acids could participate in the acylation reaction as the
acylating agents. At the same time, the presence of
electron-accepting groups in the phenyl fragment of
their diethyl esters prevented the acylation of the
substituted cycle, and the reaction occurred exclusively
at the unsubstituted phenyl moiety.
acid 1 contained the bands of the СAr–CAr stretching at
1639 and 1450 cm–1. The absorption band at 1134 cm–1
in the spectra of compounds 2 and 3 was due to the
СAr–O–CAr vibrations. The spectrum of compound 3
additionally contained the stretching band of the C≡N
group conjugated with the aryl moiety (2215–
2240 cm–1) [13].
Compounds 1–3 were used in the synthesis of the
corresponding phthalocyanine metal complexes 12 and
13 via the interaction with urea, copper or cobalt
acetate, ammonium chloride, and ammonium molyb-
date. It should be noted that when using the nitrile 3
the yield of the metal tetraanthraquinonyloxyphthalo-
cyanines 13 was higher than when using the acid 2.
Acylation of diethyl esters of biphenyl-3,4-dicar-
boxylic acid 4, 4-phenoxyphthalic acid 5, and 4-
phenoxyphthalonitrile 6 with phthalic anhydride,
followed by the intramolecular cyclization of the
formed acids 7–9 in the presence of sulfuric acid
monohydrate yielded compounds 3, 10, and 11,
respectively. Hydrolysis of diethyl esters of 4-(9,10-
dioxo-9,10-dihydroanthracen-2-yl)- (10) and 4-[(9,10-
dioxo-9,10-dihydroanthracen-2-yl)oxy]phthalic (11)
acids with 1% solution of sodium hydroxide afforded
the target derivatives of phthalic acid, 1 and 2,
respectively. The diethyl esters 4 and 5 were prepared
as described elsewhere [12] (Scheme 2).
The prepared metal complexes were blue-green
solids readily soluble in DMSO, DMF, and
concentrated sulfuric acid. Their composition and
structure were confirmed by the data of elemental
analysis, electronic absorption and IR spectroscopy,
and mass spectrometry.
IR spectra of metal complexes 12 and 13 contained
the bands at 1612–1620 and 1505–1524 (skeletal
vibrations of pyrrole rings), 1342–1360 (CN), 1246–
1288 (С–Н), 910–950 (N–Н), 850–880 (С–Н), 770–
780 (С–Н), and 734–736 (C–Н) cm–1 corresponding to
the phthalocyanine fragment [14]; on top of that, the
band assigned to the С=О groups of anthraquinone
(1645 cm–1) was retained (Scheme 3).
A special feature of IR spectra of the prepared
compounds 1–3 was the presence of absorption band at
1645 cm–1, typical of carbonyl group of anthraquinone.
The spectra of compounds 1 and 2 contained strong
absorption bands at 1700–1708 cm–1 assigned to the
carboxylic group. On top of that, IR spectrum of the
Electronic absorption spectra of compounds 12 and
13 in concentrated sulfuric acid contained several
bands differing in the intensity: the broadened Soret
band at 331–391 nm, Q-band at 743–777 nm, and
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1086
GUREEVA et al.
Scheme 3.
O
O
O
O
O
O
.
N
N
CO(NH)2, M(OAc)2 H2O,
N
M
N
NH4Cl, cat
1
N
N
N
N
O
O
12а, 12b
O
O
O
O
2
3
O
O
CO(NH)2,
M(OAc)2 H2O,
.
N
N
N
M
N
O
NH4Cl, cat
O
N
N
O
N
N
O
O
O
13а, 13b
M = Cu (a), Co (b).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

SYNTHESIS AND PROPERTIES OF TETRAANTHRAQUINONYL-
1087
D
D
1.0
1.2
1.0
0.8
0.8
0.6
0.4
0.2
0.0
0.6
0.4
0.2
λ, nm
λ, nm
Fig. 2. Electronic absorption spectrum of compound 13a in
Fig. 1. Electronic absorption spectrum of compound 12a in
H2SO4.
H2SO4.
vibrational satellites at 668–672 and 705–707 nm
(Figs. 1 and 2). Comparison of the electronic absorp-
tion spectra with those of the respective unsubstituted
phthalocyanine metal complexes [15] revealed that
introduction of anthraquinone fragments in the
molecule resulted in the blue shift of the Q-band by
about 50 nm, owing to the effect of the carbonyl
groups in the anthraquinone moiety: being strong
electron acceptors, those groups reduced the basicity of
meso-nitrogen atoms of the macrocycle. Moreover, the
protonation of carbonyl groups likely operative in the
H2SO4 solution further increased their electron-
accepting properties and enhanced the said effect. That
led to the decrease in the nitrogen atom protonation
degree in the sulfuric acid solution.
to the electronic π–π*-transitions in the main conjuga-
tion contour of the phthalocyanine macrocycle) and the
Soret short-wave bands. The strong long-wave band at
675–697 nm observed in the spectra of solutions of
phthalocyanines 12 and 13 in DMF and DMSO could
be likely assigned to the monomeric form of the
compound (Fig. 3) [16].
In summary, acylation of 4-phenoxyphthalonitrile
and diethyl esters of 4-phenoxyphthalic and biphenyl-
3,4-dicarboxylic acids with phthalic anhydride, fol-
lowed by the intramolecular cyclization with sulfuric
acid monohydrate yielded the earlier unknown 4-(9,10-
dioxo-9,10-dihydroanthracen-2-yl)- (1) and 4-[(9,10-
dioxo-9,10-dihydroanthracen-2-yl)oxy]phthalic acid
Comparison of the spectra of compounds 12 and 13
revealed that separation of the conjugation chain of
tetraanthraquinonyloxy-substituted phthalocyanine with
the oxygen atom at the attachment site of the
anthraquinone substituent induced the red shift of the
long-wave absorption band by 20–30 nm, due to the
donor properties of oxygen atom.
D
1.2
1.0
0.8
0.6
0.4
The good solubility of phthalocyanines 12 and 13
in DMF and DMSO allowed registration of the absorp-
tion spectra in those media (cf. the table). As expected,
the solvent nature significantly affected the shape of
the spectrum. In particular, the blue shift of the Q-band
was marked when concentrated sulfuric acid was
changed to DMF (Fig. 3).
0.2
0.0
λ, nm
Fig. 3. Electronic absorption spectrum of compound 12a in
DMSO.
Electronic absorption spectra of compounds 12 and
13 in DMF contained a strong long-wave Q-band (due
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 5 2016

1088
GUREEVA et al.
Electronic absorption spectral parameters (λmax, nm) for phthalo-
cyanines 12 and 13
4-Phenoxyphthalic acid diethyl ester (5). Yield
2.96 g (50.68%), white powder soluble in acetone,
DMF, and DMSO, mp 130°С. IR spectrum, ν, cm–1:
1134 (CAr–О–CAr), 1165 (OC2H5). Found, %: С 69.02;
Н 5.59; О 25.39. С18Н18О5. Calculated, %: С 68.77; Н
5.80; О 25.43.
Comp. no.
H2SO4
DMSO
12а
12b
13а
13b
668, 705, 743, 763
669,703, 745, 766
672, 707, 777
613, 675
615, 680
659, 697
660, 700
Synthesis of compounds 7–9. A mixture of
0.046 mol (6.81 g) of phthalic anhydride, 0.051 mol of
the corresponding derivative 4–6, and 20 mL of
hexane was heated to 50°С, and 16.12 g of anhydrous
aluminum chloride was added with stirring. The
obtained mixture was incubated during 3 h at 100°С,
the hexane was distilled off, and the residue was
incubated during 6 h at 120–130°С. After cooling the
mixture down to ambient, 50 mL of water and 10 mL
of concentrated sulfuric acid were added, and the
mixture was stirred during 12 h. The precipitate was
filtered off, washed with hot water, and refluxed
during 30–40 min in 10% aqueous solution of sodium
hydrocarbonate. The hot solution was filtered, and the
described treatment was repeated 3–4 times. The filtrate
was acidified with hydrochloric acid to pH 4 and
cooled to 10–15°С. The precipitate was filtered off,
washed with water to neutral reaction, and dried at 80°С.
669, 705, 776
(2) as well as 4-[(9,10-dioxo-9,10-dihydroanthracen-2-
yl)oxy]phthalonitrile (3). The interaction of the
prepared precursors with the metal salts in the presence
of urea and ammonium chloride and molybdate
afforded novel Cu- and Co-phthalocyanines containing
anthraquinone fragments.
EXPERIMENTAL
The studies were performed using the equipment
installed at the Center for Collective Usage, Ivanovo
State University of Chemistry and Technology.
Elemental analysis was performed using a FlashEA
1112 CHNS-O Analyzer instrument. Mass spectra
(MALDI-TOF) were registered using a Shimadzu
Biotech Axima Confidence mass spectrometer in the
positive ions mode with 2-(4-hydroxybenzoazo)-
benzoic acid as the matrix. Electronic absorption
spectra (250–1000 nm) were recorded using a Lambda
200 spectrometer (Perkin Elmer) at room temperature.
IR spectra (400–4000 cm–1, KBr pellets) were recorded
using an Avatar 360 FT-IR ESP instrument. Melting
points were determined using a Boetinus heating bench
equipped with an RNMK 05 observing device.
Synthesis of compounds 1–3. 0.011 mol of the
corresponding derivative 7–9 was added at vigorous
stirring at 130°С over 15 min to 20 mL of sulfuric acid
monohydrate. The obtained mixture was incubated at
150°С during 5 h and then poured in 200 mL of water.
The precipitate was filtered off, washed with water to
neutral reaction, dissolved in 100 mL of 10% aqueous
solution of sodium hydrocarbonate, and filtered off
again. The filtrate was acidified with hydrochloric acid
to pH 4. The precipitate was washed with water till the
absence of chloride ions in the filtrate. The described
treatment was repeated twice. The obtained precipitate
was dried at 100°С.
Preparation of diethyl esters of biphenyl-3,4-
dicarboxylic and 4-phenoxyphthalic acids (4, 5). A
mixture of 7.67 mmol of the corresponding acid
(biphenyl-3,4-dicarboxylic or 4-phenoxyphthalic) and
0.41 mL of concentrated sulfuric acid in 18.60 mL of
anhydrous ethanol was refluxed during 20 h. After
cooling down to ambient, the reaction mixture was
neutralized with sodium carbonate. The solvent was
distilled off, and the residue was twice recrystallized
from ethanol and dried.
In order to prepare 4-(9,10-dioxo-9,10-dihydro-
anthracen-2-yl)phthalic (1) and 4-[(9,10-dioxo-9,10-
dihydroanthracen-2-yl)oxy]phthalic (2) acids, 70 mL
of 10% solution of sodium hydroxide was added to the
obtained precipitate, and the mixture was heated on a
water bath to complete dissolution of the precipitate.
The obtained solution was acidified with hydrochloric
acid to рН 3–4; the precipitate was filtered off, washed
with water till the absence of chloride ions in the
filtrate, and dried at 100°С.
Biphenyl-3,4-dicarboxylic acid diethyl ester (4).
Yield 1.7 g (74.28%), white powder soluble in acetone,
benzene, DMF, and DMSO, mp. 155°С. IR spectrum,
ν, cm–1: 1639 and 1450 (CAr–CAr), 1165 (OC2H5).
Found, %: С 72.71; Н 5.98; О 21.31. С18Н18О4.
Calculated, %: С 72.46; Н 6.09; О 21.45.
4-(9,10-Dioxo-9,10-dihydroanthracen-2-yl)phthalic
acid (1). Yield 1.61 g (33.49%), pale brown powder
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SYNTHESIS AND PROPERTIES OF TETRAANTHRAQUINONYL-
1089
soluble in aqueous alkaline media, DMF, and DMSO,
mp 260°С. IR spectrum, ν, cm–1: 1639 and 1450 (CAr–CAr),
1645 (С=О), 1700 (СООН). Found, %: С 70.71; Н
3.86; О 25.43. С22Н12О6. Calculated, %: С 71.00; Н
3.22; О 25.78.
С88Н40СоN8О8. Calculated, %: С 75.69; Н 2.89; N
8.03; О 9.17.
Copper tetra-{4-[(9,10-dioxo-9,10-dihydroanthra-
cen-2-yl)oxy]}phthalocyanine (13a). Yield 0.22 g
(24.46%) from compound 2; 0.23 g (26.43%) from
compound 3. IR spectrum, ν, cm–1: 1134 (СAr–О–СAr),
1645 (С=О). Mass spectrum, m/z: 1462.98 [M]+
(calculated: 1463.21). Found, %: С 71.88; Н 2.78; N
7.33; О 13.67. С88Н40СuN8О12. Calculated, %: С
72.15; Н 2.76; N 7.65; О 13.11.
4-[(9,10-Dioxo-9,10-dihydroanthracen-2-yl)oxy]-
phthalic acid (2). Yield 1.69 g (35.11%), beige
powder soluble in aqueous alkaline media, DMF, and
DMSO, mp 200°С. IR spectrum, ν, cm–1: 1134
(CAr–О–CAr), 1645 (С=О), 1708 (СООН). Found, %:
С 68.28; Н 2.84; О 28.88. С22Н12О7. Calculated, %: С
68.07; Н 3.09; О 28.84.
Cobalt tetra-{4-[(9,10-dioxo-9,10-dihydroanthra-
cen-2-yl)oxy]}phthalocyanine (13b). Yield 0.19 g
(21.32%) from compound 2; 0.20 g (23.39%) from
compound 3. IR spectrum, ν, cm–1: 1134 (СAr–О–СAr),
1645 (С=О). Mass spectrum, m/z: 1459.01 [M]+
(calculated: 1459.21). Found, %: С 71.76; Н 2.69; N
7.87; О 13.64. С88Н40CoN8О12. Calculated, %: С 72.37;
Н 2.77; N 7.68; О 13.15.
4-[(9,10-Dioxo-9,10-dihydroanthracen-2-yl)oxy]-
phthalonitrile (3). Yield 1.51 g (31.82%), pale brown
powder soluble in acetone, aqueous alkaline media,
DMF, and DMSO, mp 188°С. IR spectrum, ν, cm–1:
1134 (CAr–О–CAr), 1645 (С=О), 2235 (CAr–С≡N).
Found, %: С 75.66; Н 2.38; N 8.28; О 13.68. С22Н10N2О3.
Calculated, %: С 75.43; Н 2.88; N 8.00; О 13.70.
ACKNOWLEDGMENTS
Synthesis of copper and cobalt tetraanthra-
quinonyl- and tetraanthraquinonyloxy-substituted
phthalocyanines (12, 13). A ground mixture of
0.60 mmol of the corresponding derivative 1–3, 4.00
mmol (0.24 g) of urea, 0.18 mmol of copper (0.036 g)
or cobalt (0.038 g) acetate, 0.40 mmol (0.02 g) of
ammonium chloride, and 0.01 mmol (0.002 g) of
ammonium molybdate was put in a quartz ampoule.
The mixture was slowly heated to 180°С over 1 h and
incubated at that temperature during 3 h. The mixture
was cooled down to ambient, ground, transferred onto
a glass filter, and washed with 5% hydrochloric acid
and water till no solid residue was formed upon
evaporation of the filtrate drop. The residue was dried
at 100°С, re-precipitated from concentrated sulfuric
acid, washed with acetone in a Soxhlet apparatus
during 10 h, and dried at 100°С.
This work was financially supported by Russian
Scientific Foundation (agreement 14-23-00204, synthesis
and study of physico-chemical properties of tetra-
anthraquinonoporphyrazines).
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