Synthesis, characterization and spectral properties of novel zinc phthalocyanines derived from C2 symmetric diol

Article abstract of DOI:10.1016/j.molstruc.2014.03.037

In this study, we described the syntheses of new zinc(II) phthalocyanine compounds derived from (1R,2R)-1,2-diphenyl-1,2-ethanediol units. The phthalonitrile precursors 3 and 4 were synthesized by the reaction of 4,5-dichlorophthalonitrile with (1R,2R)-1,

Full text of DOI:10.1016/j.molstruc.2014.03.037

Accepted Manuscript
Synthesis, characterization and spectral properties of novel zinc phthalocya-
nines derived from C2 symmetric diol
Yaşar Gök, Halil Zeki Gök
PII:
S0022-2860(14)00305-6
DOI:
http://dx.doi.org/10.1016/j.molstruc.2014.03.037
MOLSTR 20471
Reference:
Journal of Molecular Structure
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Accepted Date:
8 January 2014
18 March 2014
18 March 2014
Please cite this article as: Y. Gök, H.Z. Gök, Synthesis, characterization and spectral properties of novel zinc
phthalocyanines derived from C2 symmetric diol, Journal of Molecular Structure (2014), doi: http://dx.doi.org/
10.1016/j.molstruc.2014.03.037
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COVER LETTER FOR SUBMISSION OF MANUSCRIPT
Asst.Prof.Dr. Halil Zeki Gök
Osmaniye Korkut Ata University
Karacaoglan Yerleskesi
80000 Osmaniye TURKEY
Tel: +90 328 827 10 00/ 25 39
Fax: +90 328 825 00 97
e-mail: zekigok@osmaniye.edu.tr
I am enclosing herewith a manuscript entitled “Synthesis, characterization and spectral
properties of novel zinc phthalocyanines derived from C2 symmetric diol” for publication
in Journal of Molecular Structure for possible evaluation.
Kobayashi and co-workers in 1993 succeeded in combining chiral BINOL with a
phthalocyanine core and since then, limited number of reports have explored in the synthesis
of phthalocyanine bearing optically active groups. The present paper reports the synthesis and
characterization of two new optically active phthalonitriles and their zinc phthalocyanine
derivatives.
The manuscript has not been previously published, is not currently submitted for review to
any other journal, and will not be submitted elsewhere before a decision is made by this
journal.
With kind regards,

Synthesis, characterization and spectral properties of novel zinc
phthalocyanines derived from C2 symmetric diol
Yaşar Gök, Halil Zeki Gök∗
Department of Chemistry, Faculty of Arts and Sciences, Osmaniye Korkut Ata University, 80000 Osmaniye,
Turkey
Abstract
In this study, we described the syntheses of new zinc(II) phthalocyanine compounds
derived from (1R,2R)-1,2-diphenyl-1,2-ethanediol units. The phthalonitrile precursors 3 and 4
were synthesized by the reaction of 4,5-dichlorophthalonitrile with (1R,2R)-1,2-diphenyl-1,2-
ethanediol. The synthesis of zinc(II) phthalocyanine 5 and zinc(II) phthalocyanine polymer 6
by cyclotetramerization of corresponding phthalonitrile derivative were accomplished in the
presence of Zn(CH3CO2)2 in a Schlenk tube containing quinoline under nitrogen atmosphere.
The zinc(II) phthalocyanine 5 showed enhanced solubility in various organic solvents. The
aggregation behavior of phthalocyanines was investigated at different concentrations in
different solvents. Both phthalocyanines were found to exist in non-aggregated form at
concentrations between 10 x 10-6 and 1 x 10-6 mol dm-3. As the concentration increased to 5
x10-5 mol dm-3, a deviation from ideality was observed for both phthalocyanines. The novel
1
compounds were characterized by a combination of elemental analysis and H NMR, 13C
NMR, IR, UV-Vis and MS spectral data.
∗ Corresponding author. Tel.: + 90 (328)-827 1000x2539; fax: +90 (328)-825 0097; e-mail:
zekigok@osmaniye.edu.tr, Department of Chemistry, Faculty of Arts and Sciences, Osmaniye Korkut Ata
University, 80000, Osmaniye, Turkey

Keywords: C2 symmetric diol; Chiral; Phthalonitrile; Bisphthalonitrile; Zinc
phthalocyanine; Polymeric phthalocyanine
1. Introduction
Metallophthalocyanines have been intensively investigated due to their high thermal and
chemical stability along with their unique properties such as strong UV-Vis light absorption,
high molar absorption coefficients, electron transfer abilities [1]. These features promote an
extensive use of these molecules firstly as dyes and pigments [2], then as semiconductor
devices, electrochromic display devices, liquid crystals, Langmuir–Blodgett films, non-linear
optical (NLO) devices [1,3] and more recently as photosensitizers in photodynamic therapy for
cancer [4]. A goal of research on the chemistry of phthalocyanines is to achieve control over
the structure of synthetic molecules and enhance their solubility in various solvents. In order to
improve their application capabilities in scientific and technological areas, many modifications
on the peripheral or non peripheral position of the phthalocyanines have been reported [5].
Optically active compounds are ubiquitous and play a fundamental role in life,
especially in the area of pharmaceutical and agricultural industries [6]. A large number of
commercial drugs such as L-DOPA [7] and albuterol [8] contain enantiomerically pure
compounds. The design and synthesis of new optically active compounds is one of the most
important goals in modern chemistry [9]. In accordance with these goals, a lot of research has
been devoted towards the synthesis of chiral ligands such as diols [10], diamines and
disulfonamides [11], bisoxazolines [12]. Optically active diols are widely used in
enantioselective reactions due to their high enantioselectivities [13].

Chiral macrocycles, metal complexes, linear oligomers and polymers have been
synthesized for use in molecular recognition, asymmetric catalysis and as new functional
materials [14]. Kobayashi and co-workers in 1993 [15] succeeded in combining chiral BINOL
with a phthalocyanine core and since then, limited number of reports have explored in the
synthesis of phthalocyanine bearing optically active groups [16]. Most of studies among these
reports have concentrated on combining chiral binaphthol groups with a phthalocyanine core
[16,17]. Studies on combining different chiral groups with a phthalocyanine core are still
limited and spectral properties of these molecules are unknown. The functional
phthalocyanines derived from C2 symmetric diols can be interesting in enantioselective
catalytic systems, metal binding studies and photodynamic therapy.
In this paper, we synthesized and characterized mononomeric and polymeric zinc(II)
phthalocyanines 5 and 6 derived from (1R,2R)-1,2-diphenyl-1,2-ethanediol. In addition to
that, the spectral studies of these phthalocyanines in different solvent were investigated.
2. Experimental
2.1. Materials and Equipment
4,5-dichlorophthalonitrile 1 was synthesized according to reported procedure in
literature [18]. (1R,2R)-1,2-diphenyl-1,2-ethanediol 2 was efficiently prepared in high yield
via a Sharpless asymmetric dihydroxylation [19] as enantiopure diol using the known
procedure [20]. All reagents and solvents were reagent grade and were obtained from
commercial suppliers. All solvents were dried and purified as described by Perrin and
Armarego [21]. Melting points were determined with an electrothermal apparatus and are
reported uncorrected. FTIR spectra were measured on a Perkin Elmer Spectrum 65

spectrometer using KBr pellets. 1H and 13C NMR spectra were recorded on a Varian Mercury
400 MHz spectrometer using CDCl3 and DMSO-d6 (99.9%). Mass spectra were a Bruker
Daltonics MALDI-TOF spectrometer. Optical spectra were recorded in the UV-Vis region
with a PG-T80+ spectrophotometer using 1 cm-path length cuvettes at room temperature.
Elemental analyses were obtained with a LECO Elemental Analyser (CHNS 0932)
spectrophotometer. The homogeneity of the products was tested at each step using TLC.
2.2. Synthesis
The optically active phthalonitrile precursors were prepared by a nucleophilic aromatic
substitution of one of two chloro atoms 4,5-dichlorophthalonitrile 1 with one/two of two
hydroxyl functions of (1R,2R)-1,2-diphenyl-1,2-ethanediol 2.
2.2.1. Synthesis of 4-chloro-5-((1R,2R)-2-hydroxy-1,2-diphenylethoxy)phthalonitrile (3) and
5,5'-((1R,2R)-1,2-diphenylethane-1,2-diyl)bis(oxy)bis(4-chlorophthalonitrile) (4)
(1R,2R)-1,2-diphenyl-1,2-ethanediol 2 (1.3 g; 6.07 mmol) was dissolved in dry DMF
(50 ml) containing potassium carbonate (2.51 g; 18.22 mmol) as the base and stirred at 50 0C
under nitrogen atmosphere for 1 h. To this reaction mixture, a solution of 4,5-
dichlorophthalonitrile 1 (1.43 g g, 7.28 mmol) in dry dimethylformamide (50 ml) was added
to the above solution using a dropping funnel with stirring under dry inert gas over 1.5 h at 50
0C. After the addition was complete, the reaction mixture was stirred for another 22 h at 80
°C. The reaction was monitored by thin layer chromatography [hexane-ethyl acetate (7:3)].
When the reaction was complete, the mixture was filtered, and the filtrate was evaporated to
dryness under reduced pressure. The yellowish oil was dissolved in CH2Cl2. The organic layer

was washed twice with 125 ml portions of a 5% Na2CO3 solution and then twice with water.
The combined organic layer was dried over anhydrous Na2SO4 and the solvent was
evaporated under reduced pressure to give a crude product that was purified by silica gel
chromatography. The elution was carried out with dichloromethane-hexane (9:1). The first
and second band were collected and evaporated to dryness under reduced pressure to give
optically active bisphthalonitrile 4 and the 4,5-differently substituted phthalonitrile, 4-chloro-
5-((1R,2R)-2-hydroxy-1,2-diphenylethoxy)phthalonitrile 3 as white solids, respectively.
o
Experimental data for compound 3: 1.3 g (57%). Mp 153-155 C. Anal. calcd for
C22H15ClN2O2: C, 70.50; H, 4.03; N, 7.47%. Found: C: 70.01; H: 4.16; N: 7.25%. IR (KBr
disc) νmax/cm-1: 3484 (OH), 3033 (CHAr), 2907 (CHAliph), 2234 (C≡N), 1584, 1549 1491, 1454,
1
1390, 1309, 1276, 1257, 1199, 1134, 1026, 973,767, 700, 601,530. H NMR (CDCl3) δ: 7.79
(s, H, ArH), 7.30-7.03 (m, 11H, ArH), 5.27 (d, JAB = 7.34Hz, H, CH), 5.10 (d, JAB = 7.34Hz,
13
H, CH), 2.93 (s, br, 1H, OH). C NMR (CDCl3) δ: 156.82, 137.56, 134.83, 134.22, 129.33,
128.93, 128.59, 128.28, 127.21, 126.91, 118.91, 118.80, 115.40, 114.63, 114.36, 108.76,
87.69, 78.04.
(C22H17ClN2O3; calc: 392.09).
= +72.9 (c, 1.0, CHCl3). MS (ES-MS) m/z: 392.10 [M+H2O]+
o
Experimental data for compound 4: 0.314 g (22.7%). Mp 118-120 C. Anal. calcd for
C30H16Cl2N4O2: C, 67.30; H, 3.01; N, 10.46%. Found: C: 66.44; H: 3.33; N: 10.13%. IR KBr
disc) νmax/cm-1: 3036 (CHAr), 2925 (CHAliph), 2234 (C≡N), 1585, 1550, 1491, 1454, 1388,
1
1308, 1274, 1259, 1199, 1134, 1026, 974,894, 854, 767, 700, 613, 529. H NMR (CDCl3) δ:
13
7.79 (s, 2H, ArH), 7.35-7.13 (m, 12H, ArH), 5.68 (s, 2H, CH). C NMR (CDCl3) δ: 156.59,
135.02, 132.83, 129.89, 129.57, 129.08, 127.16, 118.81, 115.43, 114.61, 114.28, 109.08,
85.05.
= + 67 (c, 1.0, CHCl3). MS (ES-MS) m/z: 552.00 [M+H2O]+ (C30H18Cl2N4O3;
calc: 552.07).

2.2.2. Synthesis of zinc(II) phthalocyanine (5)
A mixture of 3 (0.150 g, 0.401 mmol), anhydrous Zn(CH3CO2)2 (0.022 g, 0.120 mmol)
and quinoline (2 ml) was heated and stirred at 190 °C for 7h in a Schlenk tube under nitrogen.
After cooling to room temperature, the product was precipitated by adding diethyl ether. The
green-blue product was filtered off and then washed successively with cold and hot water and
then 2-propanol. Finally, pure zinc(II) phthalocyanine was obtained by silica gel column
chromatography using dichloromethane. The product was then dried under vacuum over
0
P2O5. The yield was 0.033 g (22%). Mp > 300 C. Anal. calcd. for C88H60Cl4N8O8Zn: C,
67.55; H, 3.87; N, 7.16%. Found: C, 67.31; H, 3.60; N, 7.73%. IR (KBr disc) νmax/cm-1:
3440 (OH), 3062 (CHAr), 2955 (CHAliph), 1734, 1604 (C=N), 1488, 1448, 1393, 1251, 1105,
1
1067, 1015, 743, 699. H NMR (CDCl3) δ:7.74 (s, 4H, ArH), 7.66-6.98 (m, 44H, ArH), 5.33
(m, 4H, CH), 5.12 (m, 4H, CH), 2.79 (s, br, 4H, OH). UV-Vis (DMF): λ , nm (log ε): 682
max
(4.74), 612 (4.01), 360 (4.42). MS (MALDI-TOF) m/z: 1561.24 [M+H]+, 1367.64 [M+H-
C14H13O]+, 1170.87 [M+H-2C14H13O]+, 974.72 [M+H-3C14H13O]+, 778.66 [M+H-4C14H13O]+
(C88H61Cl4N8O8Zn; calc: 1561.26).
2.2.3. Synthesis of zinc(II) phthalocyanine polymer (6)
A mixture of compound 4 (0.203 g, 0.379 mmol), anhydrous Zn(CH3CO2)2 (0.034 g,
0.189 mmol) and quinoline (2 ml) was heated and stirred at 190 °C for 7 h in a Schlenk tube
under nitrogen. After cooling to room temperature, the product was precipitated by adding
ethanol (40 ml) and filtered off. The crude product was refluxed with ethanol (50 ml) in a
Soxhlet extractor for overnight. The green product was then filtered and washed with

dimethylformamide, ethanol, ethyl acetate, acetone, and diethyl ether. The product was dried
0
under vacuum over P2O5. The yield was 0.145 g (71%). Mp > 300 C. Anal. calcd. for
(C120H68Cl8N12O16Zn)n(2276.18)n for imide end groups: C, 63.13; H, 3.00; N, 7.36%. Found:
C, 63.73; H, 3.67; N, 7.96%. IR (KBr disc) νmax/cm-1: 3334 (imide N-H), 3062, 3030 (CHAr),
2970-2924 (CHAliph), 1774 (sym C=O), 1726 (asym C=O), 1655, 1602, 1434, 1343, 1248 (C-
O-C), 1099, 1067, 1015, 887, 863, 744, 699. UV-Vis (H2SO4): λ , nm (log ε): 824 (5.24),
max
732 (4.57), 312 (5.04). MS (MALDI-TOF) m/z: 2277.41 [M+H]+ ((C120H69Cl8N12O16Zn)n;
calc: (2277.17)n).
3. Result and Discussion
3.1. Synthesis and Characterization
The synthetic route to these molecules is summarized in Scheme 1. The structures of
1
novel compounds were characterized by a combination of elemental analysis and H NMR,
13C NMR, IR, UV-Vis and MS spectral data. 4,5-dichlorophthalonitrile 1 was synthesized
according to reported procedure in literature [18]. (1R,2R)-1,2-diphenyl-1,2-ethanediol 2 was
efficiently prepared in high yield via a Sharpless asymmetric dihydroxylation [19] as
enantiopure diol using the known procedure [20].
The synthesis of 4-chloro-5-((1R,2R)-2-hydroxy-1,2-diphenylethoxy)phthalonitrile 3
and 5,5'-((1R,2R)-1,2-diphenylethane-1,2-diyl)bis(oxy)bis(4-chlorophthalonitrile)
4
was
performed starting from 4,5-dichlorophthalonitrile and (1R,2R)-1,2-diphenyl-1,2-ethanediol in
N,N-dimethylformamide using K2CO3 as the base at 80 0C under nitrogen atmosphere for 22
h after purification by column chromatography. Nucleophilic aromatic displacement of one
of two chloro atoms 4,5-dichlorophthalonitrile 1 with one of two hydroxyl functions of

(1R,2R)-1,2-diphenyl-1,2-ethanediol 2 gave the 4,5-differently substituted phthalonitrile, 4-
chloro-5-((1R,2R)-2-hydroxy-1,2-diphenylethoxy)phthalonitrile 3. The chiral phthalonitrile 3
was isolated by column chromatography in reasonable good yield (57%). To determine the
1
exact structure of 3, the H NMR spectrum was acquired in CDCl3 (Fig.1). The presence of
significant resonance of OH group as broad singlet at δ = 2.93 ppm is agreement with the
proposed structure. The aliphatic CH protons were observed as two doublets at δ= 5.27 and
1
5.10 ppm with a coupling constant of J = 7.34 Hz. A singlet at δ= 7.79 ppm in the H NMR
spectrum corresponded to one of two protons of the tetrasubstituted aromatic group. The other
sets of protons were appeared as multiplet between 7.30-7.03 ppm as expected. The 13C NMR
spectrum of the same compound clearly indicated the expected carbon resonances. The nitrile
carbons were observed at δ = 114.63 and 114.36 ppm. The carbon resonances concerning
hydroxyl-connected CH and the oxygen connected CH at δ= 87.69 and 78.04 are in good
agreement with the proposed structure. The IR spectrum of 3 was easily verified with the
presence of characteristic vibrations related to OH and C≡N groups at 3483 and 2234 cm-1,
respectively (Fig.2). In addition to the elemental analysis results, the molecular ion peak at
m/z = 394.10 [M+H2O]+ in the ES/MS mass spectra of 3 also confirms the proposed structure.
The synthesis of bisphthalonitrile 4 is based on the reaction of diol 2 with compound 1.
The bisphthalonitrile 4 was obtained as minor product from the above mentioned reaction. It
was eluted as the first band from the purification of the crude product containing compound 3
and 4. The structure and purity of bisphthalonitrile 4 was identified by a combination of
1
elemental analysis and H, 13C, IR and MS spectral data. The IR spectrum of 4 was very
similar to that of 3 (Fig.2). The significant difference between the IR spectra of compounds 3
and 4 is the absence of characteristic vibration of OH group in the IR spectra of 4, confirming
the nucleophilic aromatic displacement of one of two chloro atoms 4,5-dichlorophthalonitrile
1 with the two hydroxyl group of 2. The intense absorption band at 2234 cm-1 corresponds to

the C≡N group in the IR spectrum of 4. In the 1H and 13C NMR spectra of 4, the number of the
peaks of protons and carbon resonances was obviously less than those of 3 due to the C2
symmetry of the compound 4. As a result of C2 symmetry of this compound, oxygen and
phenyl connected CH protons was observed at δ= 5.68 ppm as singlet. In addition to that, the
disappearance of the OH signals at 2.93 ppm in 1H NMR spectrum of 4 can be taken as a clear
evidence of the formation of compound 4. The signals due to the aromatic protons was
observed at δ= 7.13-7.35 ppm as multiplet. A singlet at δ= 7.79 ppm in the 1H NMR spectrum
of 4 was attributed to one of two protons of the tetrasubstituted aromatic group (Fig.1). The
13C NMR spectrum of this compound displayed the characteristic signals of the product as
expected. Elemental analysis result was consistent with the theoretical values of the proposed
structure of 4. In addition to that, the mass spectrum of 4 contained an intense peak at m/z =
552 [M+H2O]+, which support the proposed structure.
The zinc(II) phthalocyanine 5 was synthesized directly by cyclotetramerization of the
dicyano compound 3 in the presence of the anhydrous metal salt Zn(CH3CO2)2 in a Schlenk
system in quinoline. The blue green phthalocyanine was isolated by column chromatography
on silicagel. In the IR spectrum of 5, the disappearance of the sharp C≡N vibration at 2234 cm-
1
and appearance of new resonance at 1604 cm-1 corresponding to C=N vibration in
phthalocyanine core of 5 confirmed cyclotetramerization of the phthalonitrile derivative 3.
The vibration for the OH group was observed at 3440 cm-1. In the 1H NMR spectrum of 5, the
characteristic signals relating to aliphatic and aromatic groups in the phthalocyanine skeleton
gave significant resonances of the proposed structure. In addition to these results for structure,
the mass spectrum of this compound was measured using MALDI-TOF technique. The
molecular ion peaks at m/z: 1561.24 [M+H]+; the major fragment ions corresponding to loss
of C14H13O, 1367.64 [M+H-C14H13O]+, 1170.87 [M+H-2C14H13O]+, 974.72 [M+H-

3C14H13O]+ and 778.66 [M+H-4C14H13O]+ were easily identified (Fig.3). These results
confirm that the complex has been synthesized successfully.
The zinc(II) phthalocyanine polymer 6 was synthesized by heating mixture of 4 and
anhydrous metal salt Zn(CH3CO2)2 in a Schlenk system in quinoline. The zinc(II)
phthalocyanine polymer 6 was not soluble in common organic solvents such as DMF and
DMSO. Thus, the purification of metal phthalocyanine polymer was performed by washing
with various solvents as hot and cold. Zinc(II) phthalocyanine polymer 6 was characterized by
1
13
a combination of elemental analysis, IR, UV-Vis and mass spectral data. H and C NMR
could not be obtained due to the insolubility of metal phthalocyanine polymer 6 in polar
solvents such as CHCl3, DMF and DMSO. It was reported that the end groups of the metal-
free phthalocyanine polymer are cyano groups while the end groups of the
metallophthalocyanine polymers are imido groups [22]. The existence of imido groups in the
case of the metallophthalocyanine polymers was attributed to the presence of moisture during
work-up [23]. The IR spectrum of 6 was in good agreement with the proposed formulation.
The characteristic vibration of imido groups for 6 was observed at 1726 and 1774 cm-1 in the
IR spectrum of 6.
It is very difficult to determine the molecular weight of polymeric phthalocyanines
because of their poor solubility in common organic solvents. One possible procedure to
determine the degree of polymerization is IR spectroscopy, by comparison of the IR
absorption bands of the end groups with those of the bridging groups [24]. The ratios of the
absorption intensities of –C–O– (etheric) groups of the polymer (∼1240 cm-1) to the
asymmetric C=O–groups of the imides (∼1720 cm-1) were calculated (log10 I1240 / I1720). The
degree of polymerization of 6 was found as 1.44.
MALDI-TOF can be used for analysis of polymers with a great variety in structure, end
groups, and chemical properties. The function of the matrix is to absorb the laser energy and

make the polymer molecules separate from each other into a single-molecule state [25].
According to the MALDI-TOF mass spectrum analysis of 6, observation of the parent
molecular ion peaks m/z: 2277.41 [M+H]+ in the MALDI-TOF spectrum (Fig.3) of 6 verified
the proposed structures.
3.2. Absorption and aggregation properties
The best indication of the formation of phthalocyanine systems is their UV-Vis
spectrum in solution. The metallophthalocyanines show typical electronic spectra with two
strong absorption regions. One of them is in UV region at about 300-500 nm (B band) and the
other one is in the visible region at 600-800 nm (Q band) [26]. The UV-Vis absorption spectra
of zinc(II) phthalocyanines 5 in diethyl ether and conc. H2SO4 are shown in Fig.4 The
electronic spectra of zinc(II) phthalocyanine 5 display intense Q bands in the visible region at
λmax = 676 nm in diethyl ether with a weaker absorptions at λmax = 612 nm. B band absorption
was observed at λ = 352 nm for zinc(II) phthalocyanine 5 in diethyl ether. The UV-Vis
max
spectrum of zinc(II) phthalocyanine polymer 6 could be obtained in conc. H2SO4 due to its
lower solubility (Fig.4). The expected intense single Q band absorptions appeared at λ
=
max
824 nm in H2SO4 with a weaker absorptions at λmax = 732 nm. The solvent effects on the UV-
Vis spectra of metal phthalocyanine polymers were reported before [27,28]. The red shift of
the Q band in the UV-Vis spectrum of metal phthalocyanine polymer 6 showed clearly
solvent effect. B band absorptions of 6 was observed at λ = 312 nm. Both zinc(II)
max
phthalocyanine complexes 5 and 6 gave intense single Q band absorptions in their UV-Vis
spectra. An intense Q band absorption is typical of metal complexes of substituted and
unsubstituted metallophthalocyanines with D4h symmetry [29].

The aggregation behaviors of zinc(II) phthalocyanines 5 and 6 were also investigated at
different concentrations in DMF and conc. H2SO4, respectively (Fig.5). As shown in the
figures, the Q band increases in intensity with increasing in the concentration of
phthalocyanine complexes. Zinc(II) phthalocyanines 5 and 6 in DMF and conc. H2SO4,
respectively, from concentrations between 1 x 10-6 and 10 x 10-6 mol dm-3 was found to obey
the Beer-Lambert law. As the concentration increased to 5 x10-5 mol dm-3, a deviation from
ideality was observed due to the presence of aggregated species for all phthalocyanines. The
increase of the aggregation properties with the increasing concentration can be seen in Fig.5.
Organic solvents are known to reduce aggregation whereas aqueous solvents result in
highly aggregated complexes. However, many phthalocyanine complexes remain aggregated
even in non-aqueous solutions. The effects of solvents on the state of aggregation of soluble
phthalocyanines have been studied by several groups and reported in numerous papers
[30,31].
Q band absorption data obtained for zinc(II) phthalocyanine 5 are summarized in Table
1. The UV-Vis absorption spectra of zinc(II) phthalocyanines 5 in various organic solvents
are shown in Fig.6. In general, the red shift of the Q band increases with the ascending
refractive index of the solvent. In our study, the red shift of the Q band due to the solvent for
zinc(II) phthalocyanine 5 in the following order: dietheylether < tetrahydrofuran <
dichloromethane < dimethlyformamide < dimethlysulfoxide. The electronic absorption
spectra of zinc(II) phthalocyanine 5 in the various solvents was analyzed by using the method
described originally by Bayliss [32]. The plot of (n2-1) / (2n2+1), where n is the refractive
index of the solvent, versus the red shift in the Q band is shown in Fig.7. The positions of the
Q bands in these solvents show almost a linear dependence on this function. This result
suggests that the red shifts in the Q band are mainly a result of the solvation rather than
coordination [33,34].

4. Conclusion
In conclusion, we have reported the synthesis of zinc(II) phthalocyanines derived from
1
C2 symmetric diol and characterized by a combination of elemental analysis and H NMR,
13C NMR, IR, UV-Vis and MS spectral data, all of which were in agreement with the
proposed structures. A comprehensive investigation of solvent effects on the aggregation
properties of zinc(II) phthalocyanine 5 was presented. It was found that the red shifts in the Q
band are mainly a result of the solvation rather than coordination. The effect of changing
concentration on the aggregation properties for zinc(II) phthalocyanines was also studied. All
metallophthalocyanines were found to exist in monomeric form at concentrations between 1 x
10-6 and 10 x 10-6 mol dm-3. As the concentration increased to 5 x10-5 mol dm-3, a deviation
from ideality was observed due to the presence of aggregated species for all phthalocyanines.
Acknowledgements
We would like to thank The Scientific & Technological Research Council of Turkey
(TUBITAK) for their supports. Technical assistance from Department of Organic Chemistry
(S4) in Ghent University is gratefully acknowledged. We are also indebted to Dr. Ahmet
BİLGİN for his assistance with the explanation of the polymeric material.
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Figure captions:
Scheme 1. (i) K2CO3, DMF, 80 0C.; (ii) and (iii) anhyd. Zn(CH3CO2)2, dry quinoline, N2, 190
oC.
Fig. 1. 1H NMR spectra of compounds 3 and 4
Fig. 2. FT-IR spectra of compounds 5 and 6
Fig. 3. MALDI-TOF spectra of zinc(II)phthalocanines 5 and 6
Fig. 4. UV-Vis spectrum of zinc(II) phthalocyanine 5 in diethyl ether and H2SO4, and zinc(II)
phthalocyanine polymer 6 in H2SO4.
Fig. 5. Aggregation properties of zinc(II) phthalocyanine 5 in DMF and 6 in conc. H2SO4 at
different concentrations 50 x 10-6, 25 x 10-6, 12.5 x 10-6, 10 x 10-6, 8 x 10-6, 6 x 10-6, 4 x 10-6,
2x 10-6, 1 x 10-6 mol dm-3. Inset: Beer-Lambert plot.
Fig. 6. UV-Vis spectra of zinc(II) phthalocyanine 5 in various organic solvents.
Fig. 7. Plot of the Q band frequency of ZnPc 5 against (n2-1) / (2n2+1), where n is the
refractive index of the solvent

Table 1. Location of the Q band of zinc(II) phthalocyanine 5 in various organic solvents
Table 1
B band,
Refractive
index, nD
1.352
1.358
1.407
1.424
1.430
1.478
Q band, λ ,
max
Solvent
λ , (nm)
(nm)
676, 612
678, 610
678, 612
680, 612
682, 612
684, 616
max
Diethylether
Acetone
THF
DCM
DMF
DMSO
352
358
356
354
360
358
Graphical abstract
ZnPc (5) in various organic solvents
0,8
0,6
0,4
0,2
Diethylether
Acetone
THF
DCM
DMF
DMSO
0,0
600
650
700
750
800
Wavelength (nm)
The present paper reports the synthesis and characterization of two new optically active
phthalonitriles 3 and 4, and their zinc phthalocyanine derivatives 5 and 6, respectively. In addition to
that, the spectral studies of these phthalocyanines in different solvent were investigated.

HIGHLIGHTS
Synthesis, characterization and spectral properties of novel zinc phthalocyanines
derived from C2 symmetric diol
► Phthalonitrile and bisphthalonitrile derived from C2 symmetric diol. ► Monomeric and
polymeric zinc(II) phthalocyanines were synthesized. ► Enhanced solubility for zinc(II)
phthalocyanine 5 in various organic solvents.
O
OH
NC
NC
Cl
x
x
2.77
3.93
8.50
1.301.30
1.00
1.09
8.00
ppm (t1)
7.50
7.00
6.50
6.00
5.50
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00

O
O
NC
NC
CN
CN
Cl
Cl
x
x
x
x
1.00
3.66
4.05
1.02
7.5
5.0
2.5
0.0
ppm (t1)
Fig. 1.

T%
Compound 5
4000
3000
2000
1000
cm-1
T%
Compound 6
4000
3000
2000
1000
cm-1
Fig. 2.
+
[M+H-C
H O]
14 13
+
[M+H-2C H
14 13
O]
+
+
[M+H]
[M+H-3C H
14 13
O]
+
[M+H-3C H
14 13
O]

+
[M+H]
Fig. 3.
ZnPc (5) in H2SO4
1,2
0,6
0,0
ZnPc (5) in diethylether
ZnPc (6) in H2SO4
300
400
500
600
700
800
900
Wavelength (nm)

Fig. 4.
0,8
0,6
0,4
0,2
0,0
3,0
ZnPc (5)
ZnPc (5)
2,5
2,0
1,5
1,0
0,5
0,0
300
400
500
600
700
800
300
400
500
600
700
800
Wavelength (nm)
Wavelength (nm)
ZnPc (6)
ZnPc (6)
1,8
1,2
0,6
0,0
3,6
3,0
2,4
1,8
1,2
0,6
0,0
300
400
500
600
700
800
900
300
400
500
600
700
800
900
Wavelength (nm)
Wavelength (nm)
Fig. 5.

ZnPc (5) in various organic solvents
0,8
0,6
0,4
0,2
0,0
Diethylether
Acetone
THF
DCM
DMF
DMSO
600
650
700
750
800
Wavelength (nm)
Fig. 6.
Fig. 7.

Cl
Cl
OH
O
i
O
NC
NC
O
NC
NC
NC
NC
CN
CN
+
OH
(2)
HO
Cl
Cl
Cl
(3)
(1)
(4)
ii
iii
N
N
Zn
N
N
N
N
N
N
N
N
Zn
N
N
N
N
N
OH
N
O
Cl
O
Cl
Cl
O
Cl
O
Cl
O
N
Zn
N
N
N
N
OH
O
Cl
N
N
N
Zn
N
N
N
N
N
Cl
N
OH
O
N
N
O
Cl
Cl
O
O
Cl
O
Cl
Cl
O
N
N
Zn
N
OH
N
N
N
N
N
N
(5)
N
N
Zn
N
N
N
N
N
(6)
Scheme 1.