A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis, characterization, thermal stability and aggregation studies

Article abstract of DOI:10.1016/j.saa.2019.117694

This study reports the preparation, analysis, aggregation statuses and thermal properties of five phthalocyanines. The preparation of all molecules includes two steps: the first step is the preparation of phthalocyanine precursor molecules (A and B coded

Full text of DOI:10.1016/j.saa.2019.117694

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A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis,
characterization, thermal stability and aggregation studies
Songül Şahin, Erbil Ağar
PII:
S1386-1425(19)31084-4
https://doi.org/10.1016/j.saa.2019.117694
SAA 117694
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To appear in: Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
Received Date: 22 August 2019
Revised Date: 21 October 2019
Accepted Date: 22 October 2019
Please cite this article as: Songü. Şahin, E. Ağar, A3B type unsymmetrical and amphiphilic
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Graphical Abstract

A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis, characterization,
thermal stability and aggregation studies
Songül Şahin, Erbil Ağar
Ondokuz Mayıs University, Department of Chemistry, 55139, Samsun, Turkey
This study reports the preparation, analysis, aggregation statuses and thermal properties of
five phthalocyanines. The preparation of all molecules includes two steps: the first step is the
preparation of phthalocyanine precursor molecules (A and B coded phthalonitriles); the
second step is the synthesis of one metal-free and four metalled phthalocyanines (A3B-Co,
A3B-Cu, A3B-H, A3B-Ni, and A3B-Zn coded compounds). Compound A holds a
hydrophobic chain (cetyl alcohol); compound B holds a hydrophilic chain (tetraethylene
glycol). Phthalocyanines include three hydrophobic chains and one hydrophilic chain (A3B
type phthalocyanine). Characterization methods which were used to determine the structure of
these compounds are Fourier Transform Infrared (FTIR), Proton Nuclear Magnetic Resonance
(1H NMR), Carbon-13 Nuclear Magnetic Resonance (13C NMR), and Ultraviolet Visible (UV
Vis) spectroscopies and elemental analysis. The phthalocyanines have high stability up to 260
°C as a minimum value. Aggregation statuses of the phthalocyanines change to the metal
from the metal or to the solvent from the solvent.
Keywords: Phthalocyanine aggregation; Phthalocyanine; Thermal analysis; Amphiphilic
phthalocyanines; Phthalocyanine synthesis; Unsymmetrical synthesis of phthalocyanines.

1. Introduction
Phthalocyanines (Pcs) were discovered for the first time by Braun and Tcherniac in 1907
[1]. The compounds have advantageous properties such as tinctorial characteristic, high
stability, moderately cost of production, absorption in visible spectrum [2], inclusion
capability of the different metals. Due to their outstanding properties, they have a wide range
of applications areas in various fields such as laser recording materials, information storage
systems, electrochromic display devices [3], chemical sensors [4], liquid crystals [5], catalysis
[6], non-linear optics [7],
Photodynamic Therapy (PDT) [8], nanotechnology [9],
semiconductor devices [10], dye-sensitized solar cells [11], Langmuir-Blodgett films [12].
The synthesis of the symmetric metal-free and metalled phthalocyanines is well known,
on the other hand, unsymmetrical synthesis of the phthalocyanines attracted attention in the
recent years. Some studies in this field were listed in [13-22]. The unsymmetrical
phthalocyanines have unique electronic and optical properties, and different synthesis
strategies. Their synthesis and purification is more difficult from the others [2]. It has been
reported a few methods in the literature for the synthesis of A3B type unsymmetrical
phthalocyanines such as statistical condensation method [23], polymerization strategy [24,
25], Ring-Opening Metathesis Polymerization (ROMP)-capture-release [26], ring expansion
of subphthalocyanines [27-29].
In this study, our aim is to synthesize new A3B type unsymmetrical metal-free and
metallo phthalocyanines, to characterize their structures, to determine their aggregation
tendency in some organic solvents and thermal stabilities. We used statistical condensation
method on the synthesis of the phthalocyanine and reported the results of these studies in the
related sections. In this context, we chose and prepared two phthalonitrile derivatives which
have the opposite characteristics from each other. One of the substituents in the derivatives is
tetraethylene glycol (TEG), which is a member of polyethylene glycol (PEG) polymers. PEGs
comprise of ethylene oxide units, O(CH2)2, and play an important role in drug delivery
systems [30] because of their solubility both in water and organic solvents [31], selective
tumour accumulation, protection against enzymatic degradation [32], prolonged circulation
time in the body [33], less antigenicity and immunogenicity and more excellent tolerability
[34].
1

2. Experimental
The equipment and material knowledge which were used in this study were provided in
the supplementary information. Compound A [35] and compound B [36] was synthesized
according to given literatures. 4-Nitro phthalonitrile was prepared as given in [37].
2.1. Synthesis
General synthesis procedure of the phthalocyanines: (A3B-Co, A3B-Cu, A3B-H, A3B-Ni,
A3B-Zn; iii in Scheme 1)
A mixed solution of A (0.2 g, 0.54 mmol) and B (0.058 g, 0.18 mmol) was prepared in
pentanol. The temperature of the solution was increased up to 90 °C and the solution was
stirred at the same temperature for 30 minutes. Metal salt [except for A3B-H, cobalt(II)
chloride, CoCl2, (0.046 g, 0.36 mmol); copper(II) chloride, CuCl2, (0.048 g, 0.36 mmol);
nickel(II) chloride, NiCl2, (0.046 g, 0.36 mmol); zinc(II) acetate, Zn(OAc)2, (0.066 g, 0.36
mmol)] and 1,8-Diazabicyclo(5.4.0)undec-7-ene, DBU, (0.3 mL, 2 mmol) were added to the
mixture. The reaction mixture which was monitored by Thin Layer Chromatography (TLC)
was heated at reflux under nitrogen atmosphere for 48 hours. All volatile organic compounds
were removed by rotary evaporation. The colored solid was dissolved in chloroform (15 mL)
and washed with water (15 mL) three times. The organic layer was dried with sodium sulfate
(Na2SO4). The solvent was evaporated. All phthalocyanines were purified and separated with
column chromatography (dichloromethane/methanol 100:0, 99:1, 98:2, 97:3, respectively).
The same eluates were combined and concentrated to dryness.
A3B type unsymmetrical cobalt phthalocyanine (A3B-Co): Yield: 17% (0.046 g), FTIR
(Attenuated Total Reflectance, ATR), ν/cm-1: 3100-3600 (-OH), 3071 (Ar. C-H), 2921, 2852
(Al. C-H), 1598, 1487, 1463 (C=C, C=N), 1281, 1235, 1124, 1094 (C-O-C), 826, 720.
Elemental analysis: calcd (%) for C92H144N8O8Co: C 71.33; H 9.37; N 7.23. Found: C 71.29;
H 9.34; N 7.19. UV Vis (CH2Cl2), λmax nm (logε): 675 (5.24), 615 (4.83), 357 (5.00).
A3B type unsymmetrical copper phthalocyanine (A3B-Cu): Yield: 13% (0.036 g), FTIR
(ATR), ν/cm-1: 3197 (-OH), 3068 (Ar. C-H), 2919, 2851 (Al. C-H), 1607, 1488, 1467 (C=C,
C=N), 1231, 1116, 1093, 1052 (C-O-C), 824, 746, 719. Elemental analysis: calcd (%) for
C92H144N8O8Cu: C 71.12; H 9.34; N 7.21. Found: C 71.08; H 9.30; N 7.18. UV Vis (CH2Cl2),
λmax nm (logε): 6678 (4.97), 623 (4.63), 387 (4.41), 335 (4.77).
2

A3B type unsymmetrical metal-free phthalocyanine (A3B-H): Yield: 8% (0.021 g), FTIR
(ATR), ν/cm-1:3100-3600 (-OH), 3328 (-NH), 3065 (Ar. C-H), 2917, 2850 (Al. C-H), 1608,
1
1486, 1466 (C=C, C=N), 1240, 1119, 1094, 1058 (C-O-C) 821, 746, 721. H NMR (400
MHz, CDCl3) (δ: ppm): 8.36-6.97 (m, 12H Ar-H), 4.48-4.03 (m, 22H, O-CH2-CH2-O, O-
CH2-CH2), 2.14 (b, 1H, OH), 1.89-0.95 (m, 84H, -CH2-), 0.70 (t, 9H, -CH3). Elemental
analysis: calcd (%) for C92H146N8O8: C 74.05; H 9.86; N 7.51. Found: C 74.00; H 9.83; N
7.46. UV Vis (CH2Cl2), λmax nm (logε): 703 (4.94), 669 (4.91), 640 (4.66), 612 (4.53), 389
(4.66), 345 (4.92).
A3B type unsymmetrical nickel phthalocyanine (A3B-Ni): Yield: 12% (0.033 g), FTIR (ATR),
ν/cm-1: 3100-3600 (-OH), 3074 (Ar. C-H), 2918, 2850 (Al. C-H), 1610, 1531, 1485, 1466,
1
(C=C, C=N), 1241, 1121, 1093, 1066 (C-O-C), 821, 750, 720. H NMR (400 MHz, CDCl3)
(δ: ppm): 7.84-7.06 (m, 12H, Ar-H), 4.21- 4.04 (m, 22H, O-CH2-CH2-O, O-CH2-CH2), 2.05
(b, 1H, OH), 1.68-1.03 (m, 84H, -CH2-), 0.86 (t, 9H, CH3). Elemental analysis: calcd (%) for
C92H144N8O8Ni: C 71.34; H 9.37; N 7.23. Found: C 71.30; H 9.36; N 7.20. UV Vis (CH2Cl2),
λmax nm (logε): 674 (4.64), 616 (4.29), 383 (4.15), 336 (4.54).
A3B type unsymmetrical zinc phthalocyanine (A3B-Zn): Yield: 10% (0.027 g), FTIR (ATR),
ν/cm-1: 3100-3500 (-OH), 3071 (Ar. C-H), 2919, 2851 (Al. C-H), 1600, 1489, 1466 (C=C,
1
C=N), 1291, 1231, 1081 (C-O-C). 749,719. H NMR (400 MHz, CDCl3) (δ: ppm): 7.78-7.16
(m, 12H, Ar-H), 4.27-3.56 (m, 22H O-CH2-CH2-O, O-CH2-CH2), 2.05 (b, 1H, OH), 1.87-1.02
(m, 84H, -CH2-), 0.87 (t, 9H, -CH3). Elemental analysis: calcd (%) for C92H144N8O8Zn: C
71.03; H 9.33; N 7.20. Found: C 70.98; H 9.30; N 7.16. UV Vis (CH2Cl2), λmax nm (logε):
681 (5.19), 618 (4.47), 349 (4.88).
3. Results and discussion
3.1. Synthesis and characterization
In this study, five phthalocyanine compounds were synthesized. Two different
phthalonitrile precursor molecules (A and B, in Scheme 1) were used for the synthesis. One of
the precursors (A) has hydrophobic characteristic, while the other molecule has hydrophilic
characteristic (B). And so, the formed phthalocyanines show amphiphilic characteristic. The
synthesis of the similar phthalocyanines has been reported in the given references [38, 39].
The reason for using such compounds which have the opposite character is to facilitate the
separation of the compounds during column chromatography experiments. Phthalocyanines
3

that were synthesized from the derivative of two different phthalonitriles to give six possible
phthalocyanine products are A4, A3B, AABB, ABAB, AB3, B4 [40]. Statistical condensation
method which is includes one different and three identical precursor compounds (in 3:1 molar
ratios) was used for the higher yield gain of the A3B type phthalocyanines in this study.
During the purification studies, the polarity of the solvent mixtures was increased as the
purification process is ongoing so that more polar compounds were separated in different
fractions. The first fraction gave only A4 product, the second fraction gave A3B product, and
the other fractions gave the others (AABB, ABAB, AB3, and B4 which weren’t the aim in this
study).
A3B type phthalocyanines were analyzed with different techniques and the results were
found compatible with the targeted molecules (Scheme 1). UV Vis absorption spectroscopy is
an effective technique for characterization of the phthalocyanines. Phthalocyanines are
known for their two characteristic absorption bands in UV Vis spectrum: the Q band (n→ π*)
in the visible region and Soret band (B bond, π→ π*) in the near UV [41]. The Q band appears
at approximately 600-750 nm and the B band appears at approximately 300-400 nm [42]. In
the case of metal-free phthalocyanines, the Q band is divided into two [43]. In this context, all
phthalocyanines which were synthesized in this study are consistent with provided
information above. UV Vis spectra of all phthalocyanines (A3B-Co, A3B-Cu, A3B-H, A3B-
Ni, and A3B-Zn) were given in supplementary information (Fig. S. 9, Fig. S 10, Fig. S 11,
Fig. S 12, and Fig. S 13, respectively). The table 1 summarizes the UV Vis information of
synthesized phthalocyanines.
4

Scheme 1. Synthesis routes for the phthalonitriles (A and B) and phthalocyanines (A3B-Co, A3B-Cu,
A3B-H, A3B-Ni, A3B-Zn), (i) K2CO3, DMF, N2, 15 h, 105 °C, (ii) K2CO3, DMF, N2, 48 h, 45 °C, (iii)
n-pentanol, DBU, N2, 48 h, and reflux (common step for all Pcs), CoCl2 (for A3B-Co), CuCl2 (for
A3B-Cu), NiCl2 (for A3B-H), Zn(OAc)2 (for A3B-Zn).
5

A3B-Co
→
A3B-Cu A3B-H
A3B-Ni
A3B-Zn
Compound
675 (5.24) 678 (4.97) 703 (4.94) 674 (4.64), 681 (5.19)
615 (4.83) 623 (4.63) 669 (4.91) 616 (4.29), 618 (4.47)
640 (4.66)
Q Bands
nm ( log ɛ)
612 (4.53)
357 (5.00) 387 (4.41) 389 (4.66) 383 (4.15) 349 (4.88)
335 (4.77) 345 (4.92) 336 (4.54)
B Bands
nm( log ɛ)
Table 1. Absorption data for synthesized unsymmetrical phthalocyanines in CH2Cl2
The FTIR spectra of the compounds were given in Fig. S 1, Fig. S 2, Fig. S 3, Fig. S 4,
and Fig. S 5 for A3B-Co, A3B-Cu, A3B-H, A3B-Ni, and A3B-Zn, respectively. It was seen
that the CN bands both at 2229 cm-1 for A and 2225 cm-1 for B were disappeared in all spectra
after the phthalocyanine formation. It is a justification of the formation of the phthalocyanines
in addition to the UV Vis spectra. In general, stretching vibration of the OH bond at between
3100 and 3600 cm-1, aromatic protons at between 3068 and 3074 cm-1, aliphatic protons at
between 2917 and 2852 cm-1, C=C and C=N double bonds at between 1610 and 1450 cm-1,
and different C-O bonds at between 1291 and 1052 cm-1 appeared in all Pc compounds.
1
From the H NMR spectra of the phthalocyanines, it is expected that the presence of
aromatic protons in Pc ring, aliphatic protons in tetraethylene glycol and hexadecyl moieties,
methyl protons of the end group in hexadecyl and methylene protons that adjacent to oxygen
atoms, and hydroxyl proton. All of these were seen in the related spectra (Fig. S 6, Fig. S 7,
and Fig. S 8) for A3B-H, A3B-Ni, A3B-Zn, respectively. Signals of the aromatic protons
appeared at approximately between 8.36 and 6.97 ppm as a multiplet, the signals of methylene
protons which adjacent to the oxygen atoms are observed at between 4.48 and 4.03 ppm as a
multiplet, hydroxyl proton’s signal is seen at roughly 2.00 ppm as a broad peak, the signals of
free methylene protons are observed at between 1.89 and 0.95 and lastly, end group CH3’s
signal is split into a triplet and is observed at approximately 0.70 ppm.
6

3.2. Aggregation studies
Aggregation which is also known as self-assembly is defined as the association of the
phthalocyanines at changing ranges from dimers to oligomers [44]. The aggregation is
classified in different types (D, H and J type aggregation) [45] depending on the size of the
aggregation. It is an important and interesting property in many fields such as chemical and
biochemical systems. The aggregation is one of the most important characteristics of
phthalocyanines [46]. Phthalocyanines’ aggregation limits their some properties such as
photochemical activity [47, 48], nonlinear optical property [44], solubility, purification and
characterization, the effectiveness in the PDT [49]. Aggregation depends on the nature of
solvents and substituents, the metal ion in the phthahocyanine center, temperature, the
concentration of the solution and it can be measured using various methods including
electronic spectroscopy, fluorescence spectroscopy, nuclear magnetic resonance spectroscopy,
vapor pressure osmometry, calorimetry, and the others [45]. Using the UV Vis spectroscopy
is one of the most common methods in the determination of the aggregation as it can be seen
in some studies [50-54].
The monomeric states of the metalled and metal-free phthalocyanines are representable
with narrow and sharp bands in Q band region [55, 56]. When the phthalocyanines were
aggregated, the Q band absorption broadens and decreases [57-59]. The D type aggregation is
referred to dimeric species in the molecule and can be determined with decreased monomeric
band intensity and a new band appearance on the short wavelength side of the visible
spectrum; it looks like the equal two bands. H type aggregation (comes from hypsochromic
shift) expresses the larger aggregation, and J type aggregation (comes from Jelley who
discovered it) expresses the polymeric aggregation [45]. The former aggregation type (H) is
recognizable with the shift toward to blue from the region of monomeric absorption bands,
and the latter aggregation type (J) is known with the red-shift of the bands which belongs to
monomeric species [60].
In this study, the aggregation behaviors depending on the solvents of the synthesized
five phthalocyanines were examined via UV Vis spectroscopy. All phthalocyanines are
soluble in tetrahydrofuran, cyclohexane, hexane, diethyl ether, chloroform, dichloromethane
and pyridine and insoluble in common polar solvents such as water, methanol, ethanol,
acetonitrile, acetone, ethyl acetate. For this reason, in the aggregation studies of the
phthalocyanines were used in the former solvent groups. The solubility changed considerably
7

from polar solvents to apolar solvents when the phthalocyanine side chains transformed to
three alkyl chains and one polyethylene glycol chain according to our previous study in which
peg-substituted phthalocyanines were synthesized symmetrically [61].
In the context of explanations above and UV Vis spectra in different solvents of the
phtalocyanines, the aggregation investigation results were given for each phthalocyanine
below, A3B-Co, A3B-Cu, A3B-H, A3B-Ni, and A3B-Zn, respectively.
A3B-Co (Fig. 1): The phthalocyanine was found in the monomeric state in four solvent:
diethyl ether, hexane, chloroform and pyridine, on the other hand we cannot say the same
situation for tetrahydrofuran and cyclohexane solutions because of the deviation from specific
spectrum which belongs to monomeric state. The phthalocyanine shows dimeric aggregation
in tetrahydrofuran solution. Surprisingly, in the cyclohexane solution, we observed a red
shifted band together with blue shifted bands. This unusual formation may occur in different
solvents [62]. A3B-Cu (Fig. 2): The phthalocyanine was found in non-aggregated form in
pyridine, chloroform and tetrahydrofuran; whereas it was found in dimeric aggregation state
in cyclohexane and diethyl ether. A3B-H (Fig. 3): Unsymmetrical metal-free phthalocyanine
protects its monomeric form in pyridine, chloroform, tetrahydrofuran and diethyl ether; on the
other hand it forms dimeric aggregation in hexane and cyclohexane. A3B-Ni (Fig. 4):
Unsymmetrical nickel phthalocyanine complex shows aggregation formation in all solvents
with the extended version of aggregation stats. A3B-Zn (Fig. 5): The best result on behalf of
the non-aggregation belongs to the zinc phthalocyanine because there was no aggregation
formation in any solvents. It is the best candidate for further analyses.
8

Fig. 1. Aggregation behavior of A3B-Co in different solvents at 5x10-5 M.
Fig. 2. Aggregation behavior of A3B-Cu in different solvents at 5x10-5 M.
9

Fig. 3. Aggregation behavior of A3B-H in different solvents at 5x10-5 M.
Fig. 4. Aggregation behavior of A3B-Ni in different solvents at 5x10-5 M.
10

Fig. 5. Aggregation behavior of A3B-Zn in different solvents at 5x10-5 M.
In this study, we also investigated the dependence on the concentration of aggregation
behaviors of copper phthalocyanine and nickel phthalocyanine in five solvents, including
chloroform, pyridine, tetrahydrofuran, diethyl ether, and cyclohexane. It was used eight
different concentrations (in Fig. 6 and Fig. 7 for chloroform; in Fig.S 14-21 for the other
solvents) for the investigations. Both phthalocyanines obeyed the Lambert-Beer Law in the
mentioned concentrations ranges in chloroform, pyridine and tetrahydrofuran solutions. On
the other hand, the deviations from the Lambert-Beer Law were observed both diethyl ether
and cyclohexane due to aggregation formation similar to previous studies in all
concentrations. Fig. 6 shows the absorption spectra of A3B-Cu at different concentrations and
in chloroform. C1 and C8 indicate 4.06 x 10-5 M and 9.03 x 10-6 concentration values,
respectively. Fig 7 shows the absorption spectra of A3B-Ni at different concentrations and in
chloroform. There, C1 and C8 indicate 2.03 x 10-5 and 4.5 x 10-6 concentration values,
respectively.
11

Fig. 6. Absorption spectra of A3B-Cu from C1 (4.06 x 10-5 M) to C8 (9.03 x 10-6 M) at eight different
concentrations in chloroform.
Fig. 7. Absorption spectra of A3B-Ni from C1 (2.03 x 10-5) to C8 (4.50 x 10-6) at eight different
concentrations in chloroform.
12

3.3. Thermal analysis
Thermal analysis experiments were carried out in dry air atmosphere at 50 mL/min the
purge gas flow rate and 20 °C/min heating rate, by using (DTG-60/60H)/TG/DTA
simultaneous measuring instrument. Phthalocyanines were dried at 160 °C before analysis.
Thermal analysis curves of the synthesized phthalocyanines were given in supplementary
information from Fig. S 22 to Fig. S 26 for synthesized five compounds. According to the
given curves, decomposition temperatures of the phthalocyanines were found higher than 250
°C. The minimum onset of decomposition temperature is 260 °C and maximum offset is 680
°C. All phthalocyanines were decomposed in two steps. First decomposition step belongs to
the degradation of ligands (tetraethylene glycol and cetyl alcohol in the peripheral position of
the phthalocyanines) and second decomposition step belongs to the degradation of Pc
macrocyclics in all curves. Also, Thermogravimetric Analysis (TGA) curves are useful in the
determination of the Pc/ligand ratios in the phthalocyanines. Table 2 gives comprehensive
information about both theoretical and experimental results of % weight loss and the
decomposition temperature ranges for both ligands and phthalocyanines.
for ligands
for Pc ring
decomposition % weight
% weight
loss
decomposition % weight
% weight
loss
temperature
ranges (°C)
329-531
loss
temperature
ranges (°C)
531-650
loss
(found)
58.45
(calculated)
59.05
(found)
36.37
(calculated)
36.89
A3B-Co
A3B-Cu
A3B-H
336-534
260-489
320-510
320-505
59.53
61.60
58.86
58.15
59.00
61.49
59.23
58.98
534-650
489-590
510-678
505-680
37.12
37.70
36.73
37.18
37.00
38.51
36.87
37.15
A3B-Ni
A3B-Zn
Table 2. Thermal analysis results for the synthesized five unsymmetric phthalocyanines.
Conclusions
In this study, five unsymmetrical A3B type phthalocyanines (A3B-Co, A3B-Cu, A3B-
H, A3B-Ni, and A3B-Zn) were synthesized from two different phthalonitrile derivatives (A
and B). Substituents which have different characteristic (hydrophilic and hydrophobic) were
preferred to do easier the purification and separation and so, to increase the yields of the
products. Compounds were obtained relatively with good yields according to the
unsymmetrical synthesis: 17%, 13%, 8%, 12%, and 10% in return for the given order above.
13

1
All compounds were analyzed via suitable analysis techniques including UV Vis, FTIR, H
NMR, 13C NMR, elemental analysis and thermal analysis. The solubility of the
phthalocyanines was determined in common organic solvents. Aggregation behaviors of the
phthalocyanines were examined in six solvents including chloroform, cyclohexane, diethyl
ether, hexane, pyridine, tetrahydrofuran. A3B-Zn was found that in the monomeric state in all
solvents. The others protected their monomeric statuses in chloroform and pyridine solutions
as a general result. Aggregation types of the compounds changed from dimeric to higher order
complexes (except for A3B-Zn) the most effective candidate was found A3B-Zn about
aggregation matter because there was no aggregation in any solvents. Thermal stabilities of
the phthalocyanines were also examined. As anticipated, metal-free phthalocyanine was found
more unstable than metalled phthalocyanines. Decomposition started at 260 °C for metal-free
Pc and at 320 °C for metalled Pcs as a minimum onset temperature value.
Declaration of interest
Both authors affirm no conflict of interest.
Acknowledgement
The authors would like to thank Nisa Nur Can for her help. This study was supported by
Scientific Researching Projects Fund of Ondokuz Mayıs University, Samsun, Turkey. (Project
no: PYO. FEN.1904.16.012)
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18

Highlights
•
•
•
•
Preparation of the phthalonitrile derivatives and A3B-type five phthalocyanines.
Determination of the structures by spectroscopic and non-spectroscopic methods.
Investigation of the aggregation statuses in different solvents.
Determination of the thermal stabilities of all phthalocyanines.

Declaration of interests
☒ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests: