Synthesis and study of properties of the sulfonaphthylazophenoxyphthalonitrile and related phthalocyanine

Article abstract of DOI:10.1134/S1070363211110235

The 4-[4′-(5-sulfonaphthylazo)phenoxy]phthalonitrile potassium salt was synthesized by the reaction of 4-chlorophthalonitrile with 5-(4′-hydroxyphenylazo)-1-naphthalenesulfonic acid, and on its basis was obtained tetra-4-[4′-(5-sulfonaphthylazo)phenoxy]ph

Full text of DOI:10.1134/S1070363211110235

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 11, pp. 2355–2361. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © T.V. Tikhomirova, R.A. Badaukayte, V.P. Kulinich, G.P. Shaposhnikov, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81,
No. 11, pp. 1904–1909.
Synthesis and Study of Properties
of the Sulfonaphthylazophenoxyphthalonitrile
and Related Phthalocyanine
T. V. Tikhomirova, R. A. Badaukayte, V. P. Kulinich, and G. P. Shaposhnikov
Ivanovo State Chemical Technological University, pr. Engel’sa 7, Ivanovo, 153000 Russia
e-mail: ttoc@isuct.ru
Received October 18, 2010
Abstract—The 4-[4'-(5-sulfonaphthylazo)phenoxy]phthalonitrile potassium salt was synthesized by the
reaction of 4-chlorophthalonitrile with 5-(4'-hydroxyphenylazo)-1-naphthalenesulfonic acid, and on its basis
was obtained tetra-4-[4'-(5-sulfonaphthylazo)phenoxy]phthalocyanine. The products were characterized by
elemental analysis, IR and electron spectroscopy. The effect of the introduced substituent on the spectral and
other properties of the synthesized compounds was demonstrated.
DOI: 10.1134/S1070363211110235
Substituted phthalocyanines (Pc) containing sulfo-,
aryloxy-, and other groups [1–3] are well represented
in the literature. However, data on the binding of azo
and phthalocyanine chromophores are limited [4],
although such compounds are of particular interest to
scientists and practitioners, in particular as dyes.
and phthalocyanines II and III based on it, containing
in their structure a fragment of the azo dye (Scheme 1).
The nitrile I was synthesized in correspndence with
the Scheme 2.
Diazotization of 5-amino-1-naphthalenesulfonic
acid (IV) afforded the diazo compound V, which was
introduced to the azo coupling reaction with the p-
This communication is devoted to the synthesis
and study of physico-chemical properties of nitrile I
Scheme 1.
OR
RO
N
M
N
NC
NC
OR
N
N
N
N
N
N
I
OR
RO
N
MPc(OR)4
M = 2H (II), Co (III)
R =
.
N
SO3H
2355

2356
TIKHOMIROVA et al.
Scheme 2.
NH2
N
N+
N
N
ONa
NaO
COONa
NaNO2 + HCl
VI
_CO2
SO3H
SO3_
SO3Na
VII
IV
V
HCl
N
N
OH
NC
NC
Cl
, K2CO3, DMF
IХ
SO3H
VIII
N
NC
NC
O
N
SO3K
I
hydroxybenzoic acid sodium salt VI. This reaction
belongs to a particular case when the azo coupling
takes place with the displacement of substituents
(carboxyl group) [5]. The resulting dye VIII was
isolated as 5-(4'-hydroxyphenylazo)-1-naphthalene-
sulfonic acid by adding concentrated hydrochloric acid
to the solution of compound VII.
Then we used 4-chlorophthalonitrile IX, obtained
by the known procedure [6], and by nucleophilic
substitution of chlorine atom in IX by the residue R of
the azo dye VII in the medium of DMF, in the
presence of K2CO3, we obtained 4-[4'-(5-sulfo-
naphthylazo)phenoxy]phthalonitrile potassium salt I.
Choice of 4-chlorophthalonitrile IX as a substrate for
the reaction of nucleophilic substitution is due to
existing in its benzene ring of electron-withdrawing
substituents (C≡N group), which induce an effective
positive charge on the chlorine-containing carbon atom
and thus contribute to the replacement of the halogen
atom. The use of DMF as a solvent due to the fact that
in polar solvents the reaction rate of nucleophilic
substitution increases by 3–5 orders of magnitude
compared with non-polar solvents [7]. From the data in
the literature [8] we know that the role of K2CO3
consists in the transformation of ArOH into the ArO–
anion, which is more reactive in nucleophilic sub-
stitution than ArOH.
Compound I is a red-orange substance, soluble in
water, DMF, acetone, and ethanol. Its identification
was performed using the data of elemental analysis and
infrared spectroscopy. Comparing the IR spectra of the
source target nitriles, IX and I (Fig. 1), note the
ν, cm–1
Fig. 1. IR spectrum: (1) 4-chlorophthalonitrile IX and
(2) compound I.
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SYNTHESIS AND STUDY OF PROPERTIES
preservation of the bands at 2230–2240 cm–1 cor-
2357
responding to stretching vibrations of nitrile groups. In
the spectrum of the nitrile I appears an absorption band
in the range of 1250–1260 cm–1 characteristic of the
Ar–O–Ar vibrations, bands in the ranges 1430–1350
and 1210–1150 cm–1 related to the symmetrical and
asymmetrical S=O vibrations in the in sulfo group. The
band at 1630–1575 cm–1 due to the stretching
vibrations of the azo group (N=N) [9].
By heating the nitrile I at a temperature of 205–
210°C with K2CO3, which serves as an alkaline agent
[10], and subsequent reprecipitation of the product by
adding concentrated sulfuric acid, we isolated
phthalocyanine II. Synthesis of compound III was
carried out by annealing the nitrile I with anhydrous
cobalt chloride at 195–200°C.
ν, cm–1
Fig. 2. IR spectrum of phthalocyanine II.
spectrum (the number and clarity of bands) in the
synthesized compounds are smaller, which is
characteristic of phthalocyanine sulfonic acids [12]
(Fig. 2). In addition, in the spectra of phthalocyanines
II and III there are absorption bands noted for the
nitrile I and the corresponding to Ar–O–Ar, S=O, and
N=N vibrations in the substituent R. Analysis of
electron absorption spectra (EAS) of the phthalo-
cyanine I in organic solvents (DMF, DMSO) revealed
the presence of a doublet in the long wavelength
region (see the table and Fig. 3), which is characteristic
of the metal-free compounds and is explained by the
D2h symmetry [13]. In going from the phthalocyanine
II to its complex with cobalt III is observed an
increase in symmetry from D2h to D4h resulting in the
merging two components of the Q band in the EAS
into one [13]. This band is shifted bathochromically in
comparison with the CoPc Q-band (see the table and
Fig. 3).
The resulting complex III and compound II were
reprecipitated from concentrated sulfuric acid, and
final purification of II and III was performed by
column chromatography on a M60 silica gel using
DMF as eluent.
Tetra-4-[4'-(5-sulfonaphthylazo)phenoxy]phthalo-
cyanine II is a substance of dark green color, and its
cobalt complex III is a blue-green powder. The
phthalocyanines II and III are readily soluble in
DMSO, DMF and aqueous alkaline solutions.
To identify the compounds II and III we used the
data of elemental analysis, IR and electron spec-
troscopy.
When comparing the infrared spectra of the
synthesized phthalocyanines II, III with the spectra of
H2Pc and CoPc [11] was noted the coincidence of a
large number of bands, However, the resolution of the
The position of bands in electron absorption spectra
λmax, nm (D/Dmax
DMF
)
Comp. no.
DMSO
0.5% NaOH
H2SO4 vonc
325 (1.00), 634 (0.98), 675 (0.90) 672 (1.00), 698 (0.98), 325 (0.97), 645 sh (0.63) 622
524 (1.00), 825 (0.69)
II
326 (1.00), 668 (0.94),
605 sh (0.45)
666 (1.00), 325 (0.98), 600 sh (0.27)
628 (1.00),
675 (0.88)
811 (1.00), 524 (0.52)
III
–
–
385
–
–
524
VIII
X
660 (1.00), 330 (0.43), 385 (0.36), 597 sh (0.21)
784 (1.00), 524 (0.40),
693 (0.24)
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2358
TIKHOMIROVA et al.
D
D
λ, nm
λ, nm
Fig. 3. The electron absorption spectra in DMF.
D
D
λ, nm
λ, nm
Fig. 4. The electron absorption spectra in DMF.
A distinctive feature of the spectra of phthalo-
area: the CoPcs Soret band at 330 nm and absorption at
385 nm, noted earlier in the spectrum of the dye VIII
(Fig. 4). The EAS of complex III contains two
absorption bands, therewith the Q-band is broadened
and shifted bathochromically by 6 nm compared with
the Q-band of the mixture X (Fig. 3). Moreover, when
the azo-chromophore is chemically bound to the
phthalocyanine macroring the nature of the absorption
in the UV area is changed: this band becomes wider
and significantly increases in intensity, and is observed
a 5 nm hypsochromic shift of this band in comparison
with the CoPc Soret band of the mixture X. Absorption
of the fragment of azo dye in the EAS of CoPc(4-OR)4
III in organic solvents is veiled, probably due to the
overlap of that this band by the Soret band. The
intensity of the band due to the azochromofor
absorption is much less than of the Q-band, although
the molar the ratio of the azo dye to the Pc is 4: 1. This
fact was previously reported in the literature [14] and
cyanines II and III solutions in organic solvents is the
presence of absorption bands at 325–326 nm due to
electron transitions in the chromophore system of the
azo dye attached to the benzene rings of phthalo-
cyanine macroring (see the table).
Due to the absence in the EAS of a pronounced
absorption in the region characteristic for the azo-
chromophore R, in order to confirm further the
structure of the obtained phthalocyanine was prepared
a mechanical mixture X containing CoPc + dye VIII in
the ratio 1: 4 and, a the EAS of this mixture was
compared with the EAS of compounds III and VIII
(see the table). We noted the following. The EAS of
the dimethylformamide solution of azo dye VIII
contains a strong absorption band with a maximum at
385 nm (Fig. 4). In the spectrum of the mixture X there
are 3 absorption bands, two of them are in the UV
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SYNTHESIS AND STUDY OF PROPERTIES
2359
D
D
λ, nm
λ, nm
Fig. 5. The electron absorption spectra in concentrated H2SO4.
explained by the low value of its extinction coefficient
compared with that of the phthalocyanine Q-band.
color properties of the synthesized phthalocyanines II
and III. We found that they show a substantivity
toward protein and cellulose fibers and colorize them
in bright green or blue green color.
Due to the difficulty to distinguish the azo
chromophore absorption in organic solutions of the
synthesized complex III, we compared the EAS of the
above compounds in concentrated sulfuric acid. In this
case, unlike the spectrum of compound III in DMF,
we revealed the bands at 524 nm due to absorption of
the azo dye fragment and the weak Soret band. Similar
bands are revealed in the spectrum of the mixture X
(Fig. 5). In the long-wavelength region of the spectrum
the Q-band of complex III is broadened and shifted
bathochromically by 27 nm compared with the
corresponding band of the mixture X.
EXPERIMENTAL
The electron absorption spectra of the synthesized
metal complexes were recorded in the region of 300–
900 nm on a HITACHI U-2001 spectrophotometer at
room temperature. The solvents used are DMF,
DMSO, 0.5% solution of NaOH, and sulfuric acid. The
IR spectra were obtained on an AVATAR 360 FT-IR
ESP spectrophotometer. The samples were prepared by
standard KBr-tabletting technique. Elemental analysis
was performed on a CHNS-O Flash EA 1112 series
analyzer.
As can be seen from the table and Fig. 5, in the
EAS of both dye VIII, and phthalocyanines II and III
occurs bathochromic shift of the absorption bands
when going from organic solvents to sulfuric acid,
obviously due to the processes of protonation [15].
D
Four sulfonic groups in the molecules of the syn-
thesized phthalocyanine II and III provide them with
good solubility in aqueous alkaline media. In the EAS
in going from organic solvents to 0.5% solution of
NaOH is observed hypsochromic shift of the long-
wavelength band, which is associated with increased
propensity of the molecules to the association in
solution (Fig. 6).
Thus, the features of the spectral manifestations of
the compounds II and III confirm the fact of chemical
bonding of the azo and phthalocyanine chromophores.
λ, nm
Traditional for the compounds of the phthalo-
cyanine series is their application as light-resistant
dyes and pigments [5]. In this regard, we studied the
Fig. 6. The electron absorption spectra in 0.5% solution of
NaOH: (1) compound II and (2) complex III.
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TIKHOMIROVA et al.
1-Diazo-5-naphthalenesulfonic acid (V). To a
Calculated, %: C 58.52, H 2.66, N 11.37, S 6.51. IR
spectrum (KBr): 2231 (C≡N), 1182 (Ar–O–Ar), 1586
(N=N), 1118 (CS), 1208, 1386 (S=O).
porcelain cup equipped with a stirrer and a thermo-
meter placed in a water bath was poured 150 ml of
water heated to 35°C and at continuous stirring added
22.3 g (0.1 mol) of 1-amino-5-naphthalenesulfonic
acid. The solution was then acidified with 30 ml
(0.27 mol) of concentrated hydrochloric acid, and at
stirring for 30 min at 30°C to it was slowly added
dropwise 24 ml (0.13 mol) of 30% solution of sodium
nitrite from a dropping funnel. In the course of the
reaction was maintained acidic reaction of medium.
Tetra-4-[4'-(5-sulfonaphthylazo)phenyloxy]-
phthalocyanine (II). To a porcelain cup was placed a
pounded mixture of 0.49 g (0.001 mol) of 4-[4'-(5-
sulfonaphthylazo)phenyloxy]phthalonitrile potassium
salt and 0.21 g (0.0015 mol) of potassium carbonate.
The mixture was heated to 210–215°C and kept for
1 h. After cooling, the reaction mixture was crushed
and dissolved in concentrated sulfuric acid. The
resulting solution was poured on ice, the precipitate
formed was filtered off on a Schott filter, washed with
water till neutral reaction. Final purification was
performed by column chromatography on silica gel M
60 using DMF as eluent. Yield 0.63 g (33.7%). Found,
%: C 62.12, H 3.62, N 12.05, S 6.45. C96H58N16O16S4.
Calculated, %: C 63.36, H 3.21; N 12.31, S 7.05. EAS,
5-(4'-Hydroxyphenylazo)-1-naphthalenesulfonic
acid (VIII). In a porcelain cup, equipped with a stirrer
and thermometer was added 32 ml of 25% solution of
sodium carbonate and 13.8 g (0.1 mol) of p-hyd-
roxybenzoic acid. The solution was cooled by adding
ice to 8–10°C and 15 g of sodium chloride was added.
Then, at vigorous stirring from the dropping funnel
was added dropwise a solution of 1-diazo-5-naphtha-
lenesulfonic acid. The azo coupling was carried out at
a temperature of 14–15°C. After the introduction of the
whole amount of 1-diazo-5-naphthalenesulfonic acid
the stirring was continued for another 30 min. Then to
the solution was added concentrated hydrochloric acid,
the dye precipitated was filtered off on a Buchner
funnel and dried in a drier at 50°C. Yield 29.8 g
(95%). Found, %: C 58.21, H 3.86, N 8.56, S 9.51.
C16H12N2O4S. Calculated, %: C 58.53, H 3.68, N 8.53,
S 9.76. IR spectrum (KBr), ν cm–1: 1563 (N=N), 1030
(S=O). EAS, λ max, nm: 385 (DMF), 524 (H2SO4
conc.).
λ
max, nm: 325, 645, 672, 698 (DMF); 325, 634, 676
(DMSO), 622 (0.5% aqueous solution of NaOH); 524,
825 (H2SO4 conc.).
Tetra-4-[4'-(5-sulfonaphthylazo)phenyloxy]-
phthalocyanine cobalt (III). A well pounded mixture
of 0.48 g (1 mmol) of 4-[4'-(5-sulfonaphthylazo)-
phenyloxy]phthalonitrile potassium salt and 0.04 g
(0.3 mmol) of anhydrous cobalt chloride was heated to
a temperature of 195–200°C and kept for 30 min. After
cooling, the reaction mixture was crushed and
dissolved in concentrated sulfuric acid. The resulting
solution was poured on ice. The precipitate was
filtered off on a Schott filter, washed with water till
neutral reaction. Final purification was performed by
column chromatography on silica gel M 60, using
DMF as eluent. Yield 0.23 g (50%). Found, %: C 53.4,
H 2.5, N 10.1, S 4.9. C96H56CoN16O16S4. Calculated,
%: C 61.4, H 3.01, N 11.9, S 6.8. EAS, λmax, nm: 325,
666; 600 sh. (DMF); 326; 668, 605 sh. (DMSO), 628,
675 (0.5% aqueous NaOH); 524, 811 (H2SO4 conc.).
4-[4'-(5-Sulfonaphthylazo)phenyloxy]phthalonitrile
potassium salt (I). A flask equipped with stirrer,
reflux condenser and thermometer was charged with
30 ml of DMF, 1.63 g (0.01 mol) of 4-chloro-
phthalonitrile, 7.2 g (0.015 mol) of potassium carbonate
and 4.92 g (0.015 mol) of 5-(4'-hydroxyphenylazo)-1-
naphthalenesulfonic acid. The resulting mixture was
heated with stirring to 140–150°C and held at that
temperature for 3 h. End of reaction was determined
from the completness of dissolution of a sample of the
reaction mixture in water. DMF was evaporated under
vacuum. The 4-[4'-(5-sulfonaphthylazo)phenoxy]-
phthalonitrile potassium salt was extracted with
acetone in a Soxhlet apparatus. Acetone was distilled
off, dry residue was mixed with ethanol, the solution in
the alcohol solution was filtered and ethanol was
distilled off. The resulting product was dried under
vacuum. Yield 3.65 g (74.1%), mp 120–125°C. Found,
%: C 58.43, H 2.80, N 11.28, S 6.38. C24H13KN4O4S.
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