Unsymmetrical phthalocyanines with cyclopalladated azo functions

Article abstract of DOI:10.1142/S1088424612004525

In this study, a synthetic procedure for unsymmetrical metallophthalocyanines of the form M[Pc(AB₃)], where A and B refer to two different types of peripheral functionality, has been developed and the new compounds have been converted to monomeric and dimeric palladium complexes. Asymmetrically substituted phthalocyanines were synthesized with the well-known statistical condensation method, by using two differently substituted precursors, namely 4-(2-ethoxyethoxy)-1-2-dicyanobenzene (1) and 4-{4-[Z/E]-phenylazo]-1-naphthyl}oxy-1,2-dicyanobenzene (2). Consequently, electron-donating 2-ethoxyethoxy groups and electron-withdrawing palladium complex are present in the same structure. Cyclopalladation was performed with [Pd(PhCN)₂Cl₂] to yield the bis-μ-chloro-bridged dimers and subsequently, the corresponding monomers were obtained by refluxing with three equivalents of potassium acetylacetonate. The resulting products were purified by column chromatography and characterized by several chemical and spectroscopic analysis methods. All compounds have very high solubility in organic solvents due to the presence of 2-ethoxyethoxy moiety.

Full text of DOI:10.1142/S1088424612004525

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2012; 16: 192–199
DOI: 10.1142/S1088424612004525
Published at http://www.worldscinet.com/jpp/
Unsymmetrical phthalocyanines with cyclopalladated
azo functions
H.YaseminYenilmez Akkurt, Ali ihsan Okur and Ahmet Gül*◊
Technical University of Istanbul, Department of Chemistry, Maslak, Istanbul, TR-34469, Turkey
Dedicated to Professor Michael Hanack on the occasion of his 80th birthday
Received 21 October 2011
Accepted 6 November 2011
ABSTRACT: In this study, a synthetic procedure for unsymmetrical metallophthalocyanines of the form
M[Pc(AB3)], where A and B refer to two different types of peripheral functionality, has been developed
and the new compounds have been converted to monomeric and dimeric palladium complexes.
Asymmetrically substituted phthalocyanines were synthesized with the well-known statistical
condensation method, by using two differently substituted precursors, namely 4-(2-ethoxyethoxy)-1-2-
dicyanobenzene (1) and 4-{4-[Z/E]-phenylazo]-1-naphthyl}oxy-1,2-dicyanobenzene (2). Consequently,
electron-donating 2-ethoxyethoxy groups and electron-withdrawing palladium complex are present in the
same structure. Cyclopalladation was performed with [Pd(PhCN)2Cl2] to yield the bis-µ-chloro-bridged
dimers and subsequently, the corresponding monomers were obtained by refluxing with three equivalents
of potassium acetylacetonate. The resulting products were purified by column chromatography and
characterized by several chemical and spectroscopic analysis methods. All compounds have very high
solubility in organic solvents due to the presence of 2-ethoxyethoxy moiety.
KEYWORDS: phthalocyanine, azobenzene, 1-naphthol, 2-ethoxyethanol, cyclopalladation.
While the synthesis of symmetrically substituted
INTRODUCTION
phthalocyanines has been largely investigated, only
Phthalocyanines (Pcs) have attracted great research
minor attention has been devoted to the synthesis of
attention for many years because of their two-
unsymmetrical substituted phthalocyanines, owing to
dimensional p-electron conjugation, great structural
the problems associated with the low reaction yields
variety, high thermal and chemical stability, and unique
and the mixtures of differently substituted products
electrical, optical, magnetic, catalytic, mesogenic and
which render their isolation a difficult step. Usually
film-formation properties for various applications [1, 2].
the strategies to synthesize unsymmetrical substituted
MPcs have low solubility in most organic solvents and
phthalocyanines are: (a) statistical condensation of
they form aggregates. The solubility can be increased by
two differently substituted precursors; (b) the sub-
introducing alkyl or alkoxy groups into the peripheral and
phthalocyanine approach and, (c) the polymeric support
non-peripheral positions of the phthalocyanine framework
method [6–8]. The most practical and swift method is the
[3, 4]. Tetra-substituted Pcs show better solubility than
statistical condensation approach; therefore we decided
the corresponding octa-substituted phthalocyanines
to synthesize the described compounds according to the
due to the formation of constitutional isomers and the
statistical approach, which is the most useful method for
high dipole moment resulting from the unsymmetrical
the synthesis of A3B structures according to a previously
arrangement of the substituents at the periphery [5].
reported procedure [9].
There are different methods for synthesis of
asymmetric phthalocyanines. In sub-phthalocyanine
SPP full member in good standing
approach, a phthalonitrile is allowed to react with a sub-
phthalocyanine to give an asymmetric phthalocyanine.
*Correspondence to: Ahmet Gül, email: ahmetg@itu.edu.tr,
tel: +90 212-285-6827, fax: +90 212-285-6386
Copyright © 2012 World Scientific Publishing Company

UNSYMMETRICAL PHTHALOCYANINES WITH CYCLOPALLADATED AZO FUNCTIONS
193
Statistical condensation approach in turn uses two
magnetic interactions [12], optical phenomena [13],
excited-state reactivity [14], biomimetic chemistry [15],
mixed valency [16] and ionophoric activity [17]. One
strategy for the design of multimetallic systems has
involved the use of polynucleating macrocyclic ligands
[18] and, in particular, much work has been devoted to
the synthesis of porphyrins [19] and phthalocyanines
[20] that have been functionalized with appendages
that can coordinate metal ions as well. Several different
approaches to designing polynucleating porphyrins and
phthalocyanines have emerged. These include meso
substitution with ferrocenes [21, 22] or crown ethers
[23] as well as substitution with metal-ion-coordinating
pendant-arms and basket-handles [24]. There are also
examples of meso-tetrapyridylporphyrins that coordinate
metal ions peripherally via the pyridyl groups [25].
However, for most of these complexes, the extent of
electronic interaction between metal sites is quite low.
Dinuclear and mononuclear ortho-palladated
compounds are one of the most widely studied classes of
phthalonitriles in different proportions to yield a mixture
consisting of A4, A3B, A2B2, AB3 and B4 (Scheme 1).
The ratio between the two phthalonitriles are determined
according to their affinity to form macrocycles. When
the reactivity of the two phthalonitriles is relatively
similar, a 3:1 ratio has been preferred most of the time.
In such a reaction, percentage formation of A4, A3B
and other cross-condensation products has been given
as 33%, 44% and 23%, respectively [10]. The most
problematic part of asymmetric phthalocyanine synthesis
is to isolate the desired phthalocyanine from the resultant
mixture of macrocyclic products. To facilitate easy
isolation, it is crucial to choose a suitable auxilary
phthalonitrile derivative. The relative dissimilarity
of the products in solubility or in chromatographic
separation enables isolation more readily than in the
other cases. Coordination compounds prepared from
ligand systems capable of binding multiple metal ions
are of importance in studies of electron transfer [11],
Scheme 1. Statistical condensation method
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194
H.Y.Y. AKKURT ET AL.
metallomesogens [26, 27]. Some pioneering discoveries
in metallomesogens have been made with this kind of
mesogenic materials. In dimeric molecules [Pd2(µ-X)2L2]
(L = orthopalladated imines and azines) the X-bridges
determine the basic molecular shape, and consequently
have a marked influence on the mesogenic or lack of
mesogenic properties of the material [28, 29]. Thus,
thiocyanato, chloro and bromo bridges produce planar
dimeric structures prone to give mesomorphism [30, 31].
Carboxylato bridges force the molecule into a non-planar
ridge-tent (or open-book) structure.
A few years ago we have reported the synthesis
of phthalocyanines containing naphthyl-azobenzene
moieties on the periphery and cyclopalladation of these
azobenzene groups to reach binuclear and then mono-
nuclear palladium(II) complexes [32]. In the present
study, our first aim has been to extend the cyclopalladation
reaction of azo groups to unsymmetrically substituted
phthalocyanines, so the rather insoluble intermediate
bridged polymeric structures obtained in the case of
symmetrically substituted derivatives will be overcome.
The original multimetallic compounds were purified and
isolated by column chromatography and characterized by
IR, UV-vis, 1H NMR and MS.
subsequent insolubility after cyclopalladation reaction
[32], we focused on the synthesis of an unsymmetrical
phthalocyanine in AB3 structure. The second unit (B)
was 4-(2-ethoxyethoxy)phthalonitrile, which increased
the solubility but did not undergo any complexation.
Consideringthattetra-substitutedisomersaremoresoluble
than octa-substituted ones, these two monosubstituted
phthalonitrile precursors were utilized in asymmetric
phthalocyanine synthesis.
During the synthesis of unsymmetrical phthalo-
cyanines, the first step is generally to carry out the
reaction of the precursors in the presence of metal salt
in a high-boiling solvent. Since the reaction yields were
pretty low, the lithium method (elemental lithium in
pentanol) was tried and significant improvements in yield
were observed.
Mixed condensation of 4-(2-ethoxyethoxy)phthal-
onitrile with 4-[(Z/E)-phenylazo]-1-naphthyl}oxyphthal-
onitrile in the presence of lithium was performed in
n-pentanol (Scheme 3) [33]. After refluxing for 3 h, the
reaction results with the formation of the corresponding
Li2Pc as expected mixtures of constitutional isomers.
The crude product was precipitated with methanol-
water mixture, filtered and then acidification with HCl
resulted with the formation of metal-free phthalocyanine.
The desired product with AB3 structure was isolated by
column chromatography. The metallo-phthalocyanines
4 and 5 were obtained by metalation of metal-free
phthalocyanine 3 in dry DMF with cobalt chloride and
zinc acetate, respectively (Scheme 3).
Toformcomplexesthroughazobenzenefunctionalities,
we have tried the reaction of [Pd(PhCN)2Cl2] and metallo-
phthalocyanines in equimolar amounts in MeOH/benzene
at room temperature and the dimeric cyclopalladated
phthalocyanine derivative was synthesized after 48 h
(Scheme 4). The dimeric compounds can be transformed
intomonomericonesbyusingO,O-, N,O-orS,S-chelators
like acetylacetonato, 8-quinolinato, 2-picolinato,
2-quinaldato, dithiocarbamate and xanthate [28, 29].
In our case, we refluxed three equivalents of potassium
acetylacetonate (Kacac) with the dimeric compound
under nitrogen to obtain the monomeric derivative. The
solubilities of both dimeric and monomeric compounds
in chloroform, dichloromethane and tetrahydrofuran are
at satisfactory level.
RESULTS AND DISCUSSION
Our previous study about azobenzene-containing
symmetrical phthalocyanines had some drawbacks like
poor solubility and oligomer formation in palladium
complexes [32] and it led us to synthesize asymmetrically
substituted phthalocyanines. For this purpose,
2-ethoxyethoxy group which will enhance the solubility
was used. Palladium complexes of asymmetric phthalo-
cyanines have three electron-donating ethoxyethoxy
groups and one electron-withdrawing palladium
complex. This causes remarkable changes in the
electronic distribution of phthalocyanine structure.
We believe that this compound can be used in high-
technology materials.
The phthalocyanines substituted by three 2-ethox-
yethoxy and one azobenzene units were synthesized by
a two-step procedure. First, the phthalonitrile derivative
bearing a 2-ethoxy-ethoxy moiety was prepared by
a
nucleophilic ipso-nitro substitution reaction of
The structures of newly synthesized ligand and
its phthalocyanines were elucidated with elemental
analsis and ESI-MS, H NMR, IR and UV-vis spectra.
4-nitrophthalonitrile with 2-ethoxy-ethanol in the
presence of K2CO3 (Scheme 2). This dinitrile derivative
was isolated with 60% yield.
1
The structures are in accordance with the spectral
data. The sharp absorption band due to n(C≡N) in the
Since symmetrical phthalocyanines with all azoben-
zene (A) substituents lead to polymerization and
Scheme 2. Synthesis of 4-(2-ethoxyethoxy)phthalonitrile
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UNSYMMETRICAL PHTHALOCYANINES WITH CYCLOPALLADATED AZO FUNCTIONS
195
d = 3.4–4.10 ppm. The terminal CH3 was
present about d = 1.29 ppm. The NH stretching
absorption of the inner core of the metal-
free phthalocyanines was observed at around
3289 cm-1. The N–H protons of the metal-free
phthalocyanine 3 was also identified in the
1H NMR spectrum with a broad peak d = -5.67
ppm, which is a common feature of the 1H NMR
spectra of metal-free phthalocyanines [34].
UV-vis spectra of phthalocyanines are
dominated by two intense bands, an ultraviolet
Soret (B) band around 300–350 nm and a visible
Q-band around 600–700 nm. The UV-vis spectra
of 3–5 recorded in chloroform show the typical
pattern of phthalocyaninato metal complexes.
They are dominated by the p–p* transitions
within the heteroaromatic 18-p-electron system
[35–37]. The electronic absorption spectra of
3–5 exhibit a Q-band absorption at 668–704,
673, 674 nm, respectively. B-bands of these
phthalocyanines appear in the UV region at
about 335 nm (Fig. 1). An additional band was
present due to the naphthyl system at 290 nm
[38–40]. The intensity of this band was less
when compared to the symmetric derivative
[32]. The azobenzene moiety was observed as a
small shoulder around 290 nm.
The IR spectra of dimeric complexes show
some changes when converted into their
monomeric ones. For example, the IR spectrum
of monomeric Zn complex (9) shows new peaks
at 686 and 3358 cm-1. The bands at 770, 1058,
1273 and 1653 cm-1 in the dimeric complex (7)
vanished in the monomeric derivative. There
are also some minor shifts at 757 cm-1 from 744
cm-1, 938 cm-1 from 942 cm-1, but also a major
Scheme 3. Synthesis of metal-free and metallo-phthalocyanines
shift like 1558 cm-1 from 1606 cm-1.
As a result, unsymmetrical phthalocyanines bearing
dimeric and monomeric azopalladium complexes as
pendant groups were synthesized. Three 2-ethoxyethoxy
groups served as electron donor as well as solubility
enhancer.
IR spectrum of the phthalonitriles about 2230 cm-1
disappeared after phthalocyanine formation. In the
1H NMR spectrum of compound 1, the terminal CH3
and CH2 protons were observed at d = 1.25–1.19 and d =
3.62–3.53 ppm as triplet and quintet, respectively. The
internal O–CH2–CH2 moiety was present at d = 4.21–
4.18 (near aromatic system) and d = 3.82–3.78 ppm
(near aliphatic system). The aromatic protons were at
d = 7.71–7.19 ppm. EI+-GC-MS provided the molecular
ion peak for 1 at m/z = 216.
EXPERIMENTAL
IR spectra were recorded on a Perkin-Elmer Spectrum
One FT-IR spectrometer with ATR capability, electronic
spectra on a Scinco d-1000 spectrophotometer. 1H NMR
spectra were recorded on Bruker 250 MHz using TMS
as the internal reference. Elemental analyzes were
performed by the Instrumental Analysis Laboratory of
the TUBITAK Marmara Research Centre. Mass spectra
were performed on Bruker Micro TOF-LC/ESI/MS mass
spectrometer. All reagents and solvents were of reagent
grade quality obtained from commercial suppliers. The
homogeneity of the products was tested in each step by
TLC. All solvents were dried and purified as described
In the IR spectra of novel asymmetrically substituted
phthalocyanines, the peak due to n(C≡N) is absent
and aromatic CH, aliphatic CH and C–O–C vibrations
were observed about 3060, 2955–2855 and 1231 cm-1,
respectively. The characteristic napthyl band was present
1
around 745 cm-1. H NMR spectra showed the expected
chemical shifts. Aromatic protons were observed as
multiplets around d = 6.6–7.7 ppm for ZnPc and H2Pc.
The CH2 moiety near ethereal bond was seen around
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H.Y.Y. AKKURT ET AL.
Scheme 4. Synthesis of palladated azobenzene complexes
by Perrin and Armarego [41]. The solvents were stored
over molecular sieves. 4-nitrophthalonitrile [42] and
4-({4-[(Z/E)-Phenylazo]-1-naphthyl}oxy)phthalonitrile
(2) [32] were synthesized according to published
methods.
4-(2-ethoxyethoxy)phthalonitrile (1). 4-nitrophthal-
onitrile (1 g, 0.8 mmol) and excess 2-ethoxyethanol
(1 mL, 10 mmol) were dissolved in 10 mL of dry DMF.
Anhydrous K2CO3 (1.57 g, 11.4 mmol) was added in
portions over 2 h and the mixture was stirred vigorously
at 50 °C under N2 for 72 h. The reaction mixture was
poured into saturated sodium chloride solution (100
mL). The precipitated solid was filtered, washed with
water until the filtrate was neutral. The product was
dissolved in CHCl3 and dried over Na2SO4. The product
was evaporated to dryness. Yield 0.75 g (60%), mp
43 °C. Anal. calcd. for C12H12N2O2: C, 66.65; H, 5.59;
N, 12.90%. Found: C, 66.61; H, 5.64; N, 12.82. 1H NMR
(250 MHz; CDCl3; Me4Si): d, ppm 7.71–7.67 (d, 1H,
Ar–H), 7.30 (s, 1H, Ar–H), 7.25–7.19 (d, 1H, Ar–H),
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UNSYMMETRICAL PHTHALOCYANINES WITH CYCLOPALLADATED AZO FUNCTIONS
197
then dried in vacuo. Yield 0.13 g (65%), mp
> 200 °C. Anal. calcd. for C60H50CoN10O7: C,
66.60; H, 4.66; N, 12.94%. Found: C, 66.78;
H, 4.59; N, 12.83%. UV-vis (CHCl3): l, nm
(log e) 289 (4.22), 324 (4.13), 378 (3.78), 619
(3.98), 673 (4.17). IR: n, cm-1 3065 (Ar–H),
2970–2865 (alkyl CH), 1608 (C=C), 1232
(Ar–O–Ar), 1089–1065 (CH–O–CH), 749.
MS (ESI+): m/z 1081.4 (calcd. for [M]+ 1081).
2-({4-[(Z/E)-phenylazo]-1-naphthyl}-
oxy)-9,16,23-tris
(2-ethoxyethoxy)phthalo-
cyaninatozinc (5). The metal-free phtha-
locyanine 3 (0.20 g, 0.18 mmol) was dissolved
in 20 mL of dry DMF and anhydrous zinc
acetate (0.38 g, 2.1 mmol) was added and
the mixture was heated under stirring for
Fig. 1. UV-vis spectra of phthalocyanines 5, 7 and 9 in CHCl3
24 h at 80 °C. After cooling to room temperature,
the suspension was added to water (100 mL) and the
precipitated green solid was filtered and then dried in
vacuo.Yield 0.10 g (50%), mp > 200 °C. Anal. calcd. for
C60H50N10O7Zn: C, 66.20; H, 4.63; N, 12.87%. Found:
C, 66.12; H, 4.54; N, 12.95. UV-vis (CHCl3): l, nm
(log e) 289 (4.52), 342 (4.78), 614 (4.41), 674 (4.90).
1H NMR (250 MHz; CDCl3; Me4Si): d, ppm 7.61–6.82
(m, Ar–H), 3.84–3.42 (m, CH2), 1.29–1.16 (m, –CH3).
IR: n, cm-1 3058 (Ar–H), 2963–2866 (alkyl CH), 1607
(C=C), 1229 (Ar–O–Ar), 1090–1060 (CH–O–CH),
743. MS (ES+): m/z 1178.5 [M + 92+] (interpreted for
the ZnPc molecule axially coordinated by a single
2-ethoxyethoxy moiety).
Preparation of dimeric Pd complex of 4 and 5
(6 and 7). In a typical preparation, the phthalocyanine
4 (0.014 g, 1.29 × 10-5 mol) was dissolved in 1 mL
of MeOH and 1 mL of benzene under nitrogen and
equimolar amount of [Pd(PhCN)2Cl2] was added to
this mixture. After a short time, the color became dull.
The solution was stirred for 2 days. After this period
the solid was filtered off, washed several times with
n-hexane and dried in vacuo. Compound 6. Yield
15 mg (48%). Anal. calcd. for C120H98Cl2Co2N20O14Pd2:
C, 58.93; H, 4.04; N, 11.45%. Found: C, 58.65; H, 4.19;
N, 11.74. UV-vis (CHCl3): l, nm (log e) 298 (4.76), 326
(4.78), 376 (4.43), 618 (4.55), 673 (4.93). IR: d, cm-1
3058 (Ar–H), 2969–2866 (alkyl CH), 1608 (C=C), 1231
(Ar–O–Ar), 1088–1064 (CH–O–CH), 750. MS (ES+):
m/z 2440.56 (calcd. for [M–2+] 2440). Compound 7.
Yield 16 mg (51%). Anal. calcd. for C120H98Cl2N20O14Pd2
Zn2: C, 58.62; H, 4.02; N, 11.39%. Found: C, 58.65;
H, 4.23; N, 11.57. UV-vis (CHCl3): λ, nm (log e) 289
(4.05), 351 (4.46), 613 (4.08), 681 (4.65). 1H NMR (250
MHz; DMSO-d6; Me4Si): d, ppm 8.96–6.88 (m, Ar–H),
4.63–3.51 (m, CH2), 0.90–0.88 (m, –CH3). IR: d, cm-1
3053 (H–Ar), 2925–2865 (alkyl CH), 1606 (C=C), 1224
(Ar– O–Ar). MS (ES+): m/z 2470.92 (calcd. for [M +
H2O+] 2470).
4.21–4.18 (t, 2H, O–CH2), 3.82–3.78 (t, 2H, CH2–O),
3.62–3.53 (q, 2H, O–CH2), 1.25–1.19 (t, 3H, –CH3). IR:
n, cm-1 3083 (Ar–H), 2975–2872 (alkyl CH), 2233 (CN),
1561 (C=C), 1255 (CH–O–CH). GC-MS (EI): m/z 216
(calcd. for [M]+ 216).
2-({4-[(Z/E)-phenylazo]-1-naphthyl}oxy)-9,16,23-
tris (2-ethoxyethoxy)phthalocyanine(II) (3). A mixture
of 0.26 g of 1 (1.2 mmol) and 0.15 g of 4-({4-[(Z/E)-
Phenylazo]-1-naphthyl}oxy)phthalonitrile 2 (0.41 mmol)
were dissolved in 6 mL of dry 1-pentanol and heated at
140 °C under N2. After addition of elemental lithium
(0.120 g, 17.29 mmol) a green color appeared in a few
seconds. The suspension was stirred under reflux for 3 h.
The mixture was then cooled to room temperature. The
reaction mixture was poured into 1:1 water/methanol
mixture. The mixture was acidified with HCl and the
resulting precipitate was centrifuged. The precipitated
green-colored solid was filtered and washed with water,
and chromatographed over SiO2 by eluting the main
product with v/v 20:3 chloroform:tetrahydrofuran. The
pure product was finally dried in vacuo. Yield 0.18 g
(45%), mp > 200 °C. Anal. calcd. for C60H52N10O7: C,
70.30; H, 5.11; N, 13.66%. Found: C, 70.45; H, 5.22;
N, 13.57. UV-vis (CHCl3): l, nm (log e) 291 (4.04), 336
(4.32), 384 (3.95), 611 (3.91), 644 (4.09), 668 (4.25),
704 (4.25). 1H NMR (250 MHz; CDCl3; Me4Si): d, ppm
7.67–6.67 (m, Ar–H), 4.13–3.73 (m, CH2), 1.41–1.22
(m, –CH3), -5.67 (N–H). IR: n, cm-1 3289 (N–H), 3064
(Ar–H), 2956–2858 (alkyl CH), 1611 (C=C), 1231
(Ar–O–Ar), 1095–1065 (CH–O–CH), 744. MS (ES+):
m/z 1023.94 (calcd. for [M]+ 1023).
2-({4-[(Z/E)-phenylazo]-1-naphthyl}oxy)-9,16,23-
tris (2-ethoxyethoxy)phthalocyaninatocobalt(II) (4).
The metal-free phthalocyanine 3 (0.20 g, 0.18 mmol) was
dissolved in 20 mL of dry DMF and anhydrous cobalt(II)
chloride (0.27 g, 2.1 mmol) was added and the mixture
was heated under stirring for 24 h at 80 °C. After cooling
to room temperature, the suspension was added to water
(100 mL) and the precipitated blue solid was filtered and
Preparation of monomeric Pd complexes of 4
and 5 (8 and 9). In a typical preparation, the binuclear
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H.Y.Y. AKKURT ET AL.
complex 6 (0.02 g, 8.2 × 10-6 mol) was suspended in
absolute ethanol and 3 equiv. of Kacac (3.39 mg, 2.5 ×
10-5 mol) was added under nitrogen. The suspension was
refluxed for 3 h, cooled to room temperature and filtered.
The resulting dark blue solid was filtered off, washed
several times with diethyl ether and dried in vacuo.
Compound 8. Yield 0.015 g (70%). Anal. calcd. for
C66H59CoN10O9Pd: C, 60.54; H, 4.61; N, 10.86%. Found:
C, 60.68; H, 4.59; N, 12.9. UV-vis (CHCl3): l, nm (log e)
295 (4.80), 323 (4.79), 380 (4.33), 615 (4.52), 674 (4.86).
IR: d, cm-1 3060 (H–Ar), 2963–2860 (alkyl CH), 1608
(C=C), 1238 (Ar– O–Ar), 751. MS (ES+): m/z 1336.1 [M +
51+] (interpreted for the monomeric molecule in which
the cobalt ion is coordinated by an ethanol molecule,
and the N=N bond of naphthylazo moiety and the double
bond of acac ligand are reduced). Compound 9. Yield
18 mg (85%). Anal. calcd. for C66H59N10O9PdZn: C,
60.24; H, 4.59; N, 10.81%. Found: C, 60.35; H, 4.39;
N, 12.62. UV-vis (CHCl3): l, nm (log e) 288 (4.11),
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1
347 (4.04), 614 (4.03), 680 (4.05). H NMR (250 MHz;
CDCl3; Me4Si): d, ppm 7.66–6.83 (m, Ar–H), 3.65–3.42
(m, CH2), 1.40–1.16 (m, –CH3). IR: d, cm-1 3058 (H–Ar),
2969–2924 (alkyl CH), 1606 (C=C), 1237 (Ar– O–Ar),
757. MS (ES+): m/z 1290.9 (calcd. for [M]+ 1290).
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In conclusion, synthesis and characterization of
unsymmetrical phthalocyanines substituted with
phenylazonaphthyloxy- and 2-ethoxyethoxy substi-
tuents were achived by mixed cyclotetramerization of
corresponding two phthalonitrile derivatives. Cyclo-
palladation of phenylazonaphthyloxy groups with
[Pd(PhCN)2Cl2] gave the bis-µ-chloro-bridged dimers,
which were converted to the corresponding monomers by
refluxing with potassium acetylacetonate. Three 2-ethox-
yethoxy substituents served as electron donors as well as
solubility enhancers. The azobenzene moiety formed a
complex with palladium(II) ion and this entity was added
to the phthalocyanine molecule as an electron-withdrawing
group. Since electron-donating and electron-withdrawing
groups are brought together in the same molecule, a
promising new family of phthalocyanines was synthesized
with interesting optical and electrical properties.
˘
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This study was supported by Research Funds of
Istanbul Technical University.
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