Microwave-assisted synthesis and characterization of novel metal-free and metallophthalocyanines containing four 14-membered tetraaza macrocycles

Article abstract of DOI:10.1016/j.jorganchem.2007.02.013

The novel tetrasubstituted metal-free phthalocyanine (6) and metallophthalocyanines (7, 8) bearing four 14-membered tetraaza macrocycles moieties on peripheral positions have been synthesized by cyclotetramerization reaction of phthalonitrile derivative (

Full text of DOI:10.1016/j.jorganchem.2007.02.013

Journal of Organometallic Chemistry 692 (2007) 2436–2440
www.elsevier.com/locate/jorganchem
Microwave-assisted synthesis and characterization
of novel metal-free and metallophthalocyanines
containing four 14-membered tetraaza macrocycles
a
a,
b
Zekeriya Bıyıklıog˘lu , Halit Kantekin *, Musa Ozil
¨
a
Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
b
Department of Chemistry, Rize Faculty of Arts and Sciences, Rize University, 53050 Rize, Turkey
Received 16 November 2006; received in revised form 13 February 2007; accepted 15 February 2007
Available online 20 February 2007
Abstract
The novel tetrasubstituted metal-free phthalocyanine (6) and metallophthalocyanines (7, 8) bearing four 14-membered tetraaza mac-
rocycles moieties on peripheral positions have been synthesized by cyclotetramerization reaction of phthalonitrile derivative (5) in a
multi-step reaction sequence. The new compounds were characterized by a combination of IR, 1H NMR, 13C NMR, UV–vis, elemental
analysis and MS spectral data.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Phthalocyanine; Tetraazamacrocycle; Template effect; Macrocyclization; Tosylation
1. Introduction
The growing use of phthalocyanines as advanced mate-
rials during the last decade has encouraged research on the
synthesis of new derivatized materials which differ in the
central metal ion or in the peripheral substituents. Despite
this extensive interest, there are relatively few synthetic
routes to phthalocyanine derivatives, covering mainly pht-
halonitrile derivatives compounds [2].
Microwave-promoted organic reactions as well known
as environmentally benign methods that can accelerate a
great number of chemical processes. In particular, the
reaction time and energy input are supposed to be mostly
reduced in the reactions that are run for a long time at high
temperatures under conventional conditions [12].
Microwave-assisted synthesis of phthalocyanines is novel
[13–22].
We have previously synthesized phyhalocyanines con-
taining tetrathiadiaza [23] and diazatetrathia [24] macrobi-
cyclic moieties. In this paper, we have rapidly prepared
metal-free and metallophthalocyanines by microwave
irradiation and we describe characterization of the new
metal-free and metallophthalocyanines, bearing tetraaza
macrocyclic moieties.
Phthalocyanines and their metal complexes have
attracted considerable attention as a result of their diverse
optical, electronic, and coordination properties which have
led to wide-ranging research for over 60 years [1–3]. In the
last 20 years, phthalocyanine chemistry is undergoing a
renaissance because these compounds and their derivatives
exhibit singular and unconventional properties interesting
for applications in the areas of non-linear optics, liquid
crystals, electrochromic processes involving thin films, gas
or chemical sensors photosensitizers, catalysts and for mer-
captan oxidations and as therapeutic agents in pharmacol-
ogy [4–9]. A disadvantage of phthalocyanines is their
limited solubility in common organic solvents. For most
of these applications, phthalocyanines with long chains or
macrocyclic moieties [10,11] had to be synthesized in order
to facilitate the above mentioned purposes and to enhance
solubility.
*
Corresponding author. Tel.: +90 462 377 2589; fax: +90 462 325 3196.
E-mail address: halit@ktu.edu.tr (H. Kantekin).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.02.013

Z. Bıyıklıog˘lu et al. / Journal of Organometallic Chemistry 692 (2007) 2436–2440
2437
2. Experimental
in dry acetonitrile (200 ml),finely ground anhydrous
K2CO3 (3.25 g, 23.58 mmol) was added and the mixture
stirred for 2 h at 50 ꢁC. A solution of 1,2-dichloro-4,5-dicy-
anobenzene 4 (1.54 g, 7.86 mmol) in dry acetonitrile (60 ml)
was added dropwise over 4 h. After stirring for 4 days at
85 ꢁC, the reaction mixture was poured into ice-water
and stirred for 2 h. The mixture was evaporated until
20 ml under reduced pressure. The residue was extracted
with (2 · 100) ml of chloroform. The organic layer was
dried over anhydrous magnesium sulfate and the solvent
was evaporated under reduced pressure to give a orange
crude product. The crude product was chromatographed
on silica gel with chloroform as eluents. Yield: 3.03 g
(61%), mp: 155–157 ꢁC. Anal. Calc. for C32H36N6O4S2:
C, 60.74; H, 5.73; N, 13.28. Found: C, 60.39; H, 5.93; N,
13.56%. IR (KBr tablet) mmax/cmꢀ1: 3082 (Ar–H), 2924–
2853 (Aliph. C–H), 2237 (C„N), 1591 (N–H bending),
3,30-Piperazine-1,4-diyldipropan-1-amine 1 [25], 1,2-
dichloro-4,5-dicyanobenzene 4 [26] were prepared accord-
ing to the literatures. All reagents and solvents were of
reagent grade quality and were obtained from commercial
suppliers. All solvents were dried and purified as described
by Perrin and Armarego [27]. The IR spectra were recorded
on a Perkin–Elmer 1600 FT-IR Spectrophotometer, using
KBr pellets or NaCl disc. H and 13C NMR spectra were
1
recorded on a Varian Mercury 200 MHz spectrometer in
CDCl3, DMSO-d6, and chemical shifts were reported (d)
relative to Me4Si as internal standard. Mass spectra were
measured on a Micromass Quatro LC/ULTIMA LC–
MS/MS spectrometer. Elemental analyses were determined
by a LECO Elemental Analyser (CHNS O932) and Uni-
cam 929 AA spectrophotometer, respectively. Melting
points were measured on an electrothermal apparatus
and are uncorrected. Optical spectra in the UV–vis region
were recorded with a Unicam UV2-100 spectrophotometer,
using 1 cm pathlength cuvettes at room temperature.
Domestic microwave oven were used all synthesis of
phthalocyanines.
1
1467, 1320–1142 (SO2), 1092, 916, 810, 733, 659, 550. H
NMR. (CDCl3), (d: ppm): 7.98 (s, 2H, Ar–H), 7.57 (d,
4H, Ar–H), 7.33 (d, 4H, Ar–H), 4.57 (t, 4H, CH2–N),
2.60 (t, 4H, CH2–N), 2.41 (s, 6H, CH3), 2.39 (t, 8H,
CH2–N), 1.71 (m, 4H, CH2–CH2). 13C NMR. (CDCl3),
(d: ppm): 144.72, 135.18, 129.86, 128.56, 127.21, 119.43,
115.31, 112,72, 59.41, 58.41, 52.97, 29.92, 21.74 . MS
(FAB), (m/z): 635 [M+3]+, 671 [M+K]+.
2.1. 1,12-Bis[(4-methyl)sulfonyl]-1,2,3,4,6,7,9,10,11,12-
decahydro-5,8-ethanododecine (3)
2.3. Metal-free phthalocyanine (6)
3,30-Piperazine-1,4-diyldipropan-1-amine 1 (3 g, 14.97
mmol) was dissolved in pyridine (30 ml) under nitrogen
A
mixture
4,6,7,9,10,11,12-decahydro-5,8-ehano-1,5,8,12-benzotetra-
azacyclotetradecine-14,15-dicarbonitrile (0.7 g, 1.10
of
1,12-bis[(4-methyl)sulfonyl]-1,2,3,
and powdered toluene-p-sulfonylchloride
2
(7.13 g,
37.42 mmol) was added portionwise over 0.5 h to the stir-
red and cooled in ice-salt bath at ꢀ10 ꢁC. Stirring and cool-
ing of the reaction mixture was continued for 1.5 h at
ꢀ10 ꢁC, then the mixture was stirred at room temperature
overnight. The solution was poured slowly on ice (100 g)
and diluted with water (100 ml). The precipitated ditosylate
was filtered off and washed with cold water and diethyl
ether . The product was dried in vacuo and obtained as a
yellow solid. Yield: 4.95 g (65%), mp: 181–183 ꢁC. Anal.
Calc. for C24H36N4O4S2: C, 56.66; H, 7.13; N, 11.01.
Found: C, 56.38; H, 7.28; N, 11.28%. IR (KBr tablet)
5
mmol) and 2-(dimethylamino)ethanol (2 ml) was irradiated
in a microwave oven at 175 ꢁC, 350 W for 8 min. After
cooling to room temperature the reaction mixture refluxed
with ethanol to precipitate the product which was filtered
off. The dark green product was washed with hot ethanol
(40 ml) and dried in vacuo. The solid product was chro-
matographed on silica gel with chloroform/methanol
(9:1) as eluents. This product is soluble in DMF, DMSO
and pyridine. Yield: 215 mg (31%), mp > 300 ꢁC. Anal.
Calc. for C128H146N24O16S8: C, 60.68; H, 5.80; N, 13.26.
Found: C, 60.39; H, 6.28; N, 13.03%. IR (KBr tablet)
m
max/cmꢀ1: 3250 (N–H), 3027 (Ar–H), 2956–2848 (Aliph.
C–H), 1596 (N–H bending), 1478, 1321–1157 (SO2), 1096,
m
max/cmꢀ1: 3325 (N–H), 3075 (Ar–H), 2923–2846 (Aliph.
C–H), 1621, 1596, 1443, 1399–1155 (SO2), 1079, 1015,
932, 886, 749. H NMR. (DMSO-d6), (d: ppm) 8.23–7.70
1
990, 810, 658, 572. H NMR. (CDCl3), (d: ppm): 7.63 (d,
1
4H, Ar–H), 7.25 (d, 4H, Ar–H), 6.12 (s, 2H, NH), 3.45
(t, 4H, CH2–N), 2.43 (t, 8H, CH2–N), 2.40 (s, 6H, CH3),
2.31 (t, 4H, CH2–N), 1.81 (m, 4H, CH2–CH2). 13C
NMR. (CDCl3), (d: ppm): 143.11, 137.01, 129.60, 126.95,
57.85, 53.02, 44.21, 23.85, 21.51. MS (EI), (m/z): 509
[M+1]+.
(m, 8H, Ar–H), 7.57–7.31 (d, 32H, tosyl Ar–H), 4.53 (t,
16H, CH2–N), 2.67 (t, 32H, CH2–N), 2.59 (t, 16H, CH2–
N), 2.40 (s, 24H, CH3), 1.67 (m, 16H, CH2–CH2), ꢀ4.98
(br, 2H, D2O exchangeable NH) : UV–vis (pyridine):
k
max/nm: [(10ꢀ5 e dm3 molꢀ1 cmꢀ1)]: 288 (4.96), 321
(4.88), 344 (4.75), 431 (4.56), 620 (4.61), 686 (4.72). MS
2.2. 1,12-Bis[(4-methyl)sulfonyl]-1,2,3,4,6,7,9,10,11,12-
decahydro-5,8-ethano- 1,5,8,12-benzo
tetraazacyclotetradecine-14,15-dicarbonitrile (5)
(FAB), (m/z): 2533 [M]+.
2.4. Nickel(II) phthalocyanine (7)
1,12-Bis[(4-methyl)sulfonyl]-1,2,3,4,6,7,9,10,11,12-deca-
A
mixture of 1,12-bis[(4-methyl)sulfonyl]-1,2,3,4,
hydro-5,8-ethanododecine 3 (4 g, 7.86 mmol) was dissolved
6,7,9,10,11,12-decahydro-5,8-ehano-1,5,8,12-benzotetra-

2438
Z. Bıyıklıog˘lu et al. / Journal of Organometallic Chemistry 692 (2007) 2436–2440
azacyclotetradecine-14,15-dicarbonitrile 5 (0.7 g, 1.10 mmol),
anhydrous NiCl2 (35.66 mg, 0.27 mmol) and 2-(dimethyla-
mino)ethanol (2 ml) was irradiated in a microwave oven at
175 ꢁC, 350 W for 8 min. After cooling to room tempera-
ture the reaction mixture refluxed with ethanol to precipi-
tate the product which was filtered off. The green product
was washed with hot ethanol (30 ml) and dried in vacuo.
The solid product was chromatographed on silica gel with
chloroform/methanol (3:1) as eluents. This product is solu-
ble in DMF, DMSO and pyridine. Yield: 195 mg (28%),
mp > 300 ꢁC. Anal. Calc. for C128H144N24O16S8Ni: C,
59.36; H, 5.60; N, 12.97; Ni, 2.26. Found: C, 58.97; H,
amine 1 [25], 1,2-dichloro-4,5-dicyanobenzene 4 [26] were
prepared according to the literatures (Fig. 1).
The aliphatic amine groups of 1 was tosylated in pyri-
dine at ꢀ10 ꢁC with p-toluenesulfonylchloride 2 to protect
amino groups and to make use of the high reactivity of
tosylamides in further cyclization reactions. 1H NMR,
13C NMR, IR, and MS spectra verified the structure of
3. In the IR spectrum of 1, the intense absorption bands
at 3351–3292 cmꢀ1 for 1, corresponding to the –NH2
groups, disappear after the conversion to the tosylamino
compounds. The rest of the spectra of 1 resembles closely
that of 3 including the characteristic vibration of aliphatic
and other groups. The IR spectrum of 3 clearly indicates
the presence of N–H group by the intense stretching bands
5.82; N, 12.43; Ni, 2.58%. IR (KBr tablet) mmax/cmꢀ1
:
3076 (Ar–H), 2924–2840 (Aliph. C–H), 1618, 1597, 1418,
1391–1153 (SO2), 1075, 966, 888, 785. 1H NMR.
(DMSO-d6), (d: ppm): 8.25–7.72 (m, 8H, Ar–H), 7.60–
7.33 (d, 32H, tosyl Ar–H), 4.68 (t, 16H, CH2–N), 2.74 (t,
32H, CH2–N), 2.65 (t, 16H, CH2–N), 2.49 (s, 24H, CH3),
1.81 (m, 16H, CH2–CH2) UV–vis (pyridine): kmax/nm:
[(10ꢀ5 e dm3 molꢀ1 cmꢀ1)]: 278 (4.87), 305 (4.74), 395
(4.68), 611 (4.45), 687 (4.68). MS (FAB), (m/z): 2589
[M]+.
1
at 3250 cmꢀ1. H NMR spectra of 3 are almost identical,
with only small changes in shifts. The difference between
the two spectra of tosylated amino and free amino groups
1 and 3 is clear from the presence of sulfonamide bands in 3
at 6.12 ppm. 13C NMR spectrum of 3 clearly indicates the
presence of tosyl Ar–H group by the intense bands in 3 at
143.11, 137.01, 129.60 and 126.95 ppm. The MS mass spec-
trum of 3, which shows a peak at m/z = 509 [M+1]+ sup-
port the proposed formula for this compound.
Compound 5 was prepared from 1,12-bis[(4-methyl)sul-
fonyl]-1,2,3,4,6,7,9,10,11,12-decahydro-5,8- ethanodode-
cine 3 with 1,2-dichloro-4,5-dicyanobanzene 4 in dry
acetonitrile containing potassium carbonate as the base
[28,29]. The reaction was carried out in dry acetonitrile at
85 ꢁC and gave moderate yields (61%). Comparison of
the IR spectral data clearly indicated the formation of com-
pound 5 by the disappearance of the C–Cl band of 1,2-
dichloro-4,5-dicyanobanzene at 684 cmꢀ1 and of NH band
of compound 3 at 3250 cmꢀ1, and the appearance of a new
absorption at 2237 cmꢀ1 (C„N). The spectrum of 5 also
indicates the presence of alkyl, CN, and SO2 groups by
the intense stretching bands at 2924–2853 (C–H), 2237
2.5. Zinc(II) phthalocyanine (8)
A mixture of 1,12-bis[(4-methyl)sulfonyl]-1,2,3,4,6,7,9,
10,11,12-decahydro-5,8-ehano-1,5,8,12-benzotetraaza-
cyclotetradecine-14,15-dicarbonitrile 5 (0.7 g, 1.10 mmol),
anhydrous zinc acetate (50.42 mg, 0.27 mmol) and 2-(dim-
ethylamino)ethanol (2 ml) was irradiated in a microwave
oven at 175 ꢁC, 350 W for 8 min. After cooling to room
temperature the reaction mixture refluxed with ethanol to
precipitate the product which was filtered off. The blue
product was washed with hot ethanol (35 ml) and dried
in vacuo. The solid product was chromatographed on silica
gel with chloroform/ethanol (3:2) as eluents. This product
is soluble in DMF, DMSO and pyridine. Yield: 229 mg
(32%), mp > 300 ꢁC. Anal. Calc. for C128H146N24O16S8Zn:
C, 59.20; H, 5.58; N, 12.94; Zn, 2.51. Found: C, 58.78; H,
6.04; N, 12.61; Zn, 2.88%. IR (KBr tablet) mmax/cmꢀ1: 3082
(Ar–H), 2923–2851 (Aliph. C–H), 1624, 1598, 1410, 1371–
1182 (SO2), 1087, 938, 891, 742. 1H NMR. (DMSO-d6), (d:
ppm): 8.27–7.74 (m, 8H, Ar–H), 7.59–7.32 (d, 32H, tosyl
Ar–H), 4.55 (t, 16H, CH2–N), 2.70 (t, 32H, CH2–N), 2.60
(t, 16H, CH2–N), 2.42 (s, 24H, CH3), 1.71 (m, 16H,
1
(C„N) and 1320–1142 cmꢀ1 (–SO2). H NMR spectra of
5 showed a new signal due to aromatic proton at
1
d = 7.98 ppm, as expected. While the H NMR spectra of
3 and 5 are similar, the proton-decoupled 13C NMR spec-
trum indicated the presence of the nitrile carbon atoms in 5
at d = 112.72 ppm. The MS mass spectrum of compound 5,
which shows a peak at m/z = 635 [M+3]+, 671 [M+K]+
support the proposed formula for this compound.
Metal-free phthalocyanine 6 was synthesized by micro-
wave irradiation of the corresponding dicyano compound
5 in 2-(dimethylamino)ethanol for 8 min. The IR spectrum
of metal-free phthalocyanine 6 shows the 3325 (NH), 3075
(Ar–H) vibrations. The inner core N–H protons of metal-
free phthalocyanine 6 were also identified in the 1H
NMR spectrum. At high concentration strong shielding
of the cavity protons in the phthalocyanine core of this
compound was indicated by a broad resonance at
d = ꢀ4.98 ppm [23,30] which could be attributed to the
NH resonance. The signals related to aromatic protons
and aliphatic protons in the macrocyclic moieties and
phthalocyanine skeleton gave significant absorbance char-
CH2–CH2). UV–vis (pyridine):
k
max/nm: [(10ꢀ5
e
dm3 molꢀ1 cmꢀ1)]: 268 (5.15), 310 (5.01), 350 (4.84), 620
(4.53), 686 (4.94). MS (FAB), (m/z): 2597 [M+1]+.
3. Results and discussion
The preparation of the target metal-free 6 and metall-
ophthalocyanines 7, 8 is shown in Scheme 1. The structures
of novel compounds were characterized by a combination
1
of H NMR, 13C NMR, IR, UV–vis, elemental analysis
and MS spectral data. 3,30-Piperazine-1,4-diyldipropan-1-

Z. Bıyıklıog˘lu et al. / Journal of Organometallic Chemistry 692 (2007) 2436–2440
2439
NN
N
H2
O
S
NN
N
H
Ts
Cl
Cl
CN
CN
pyridine
-10º C
Cl
CH3
NH2
O
NH Ts
(2)
(4)
(1)
50º C
(3)
K2CO3
dry CH3CN
Ts
Ts
NN
N
CN
N
CN
(5)
DMAE MW 350 W
N
N
N
Ts
N
Ts
N
N
N
N
N
Ts
Ts
N
N
N
N
N
N
M
N
Ts
N
Ts
N
N
N
Ts
N
Ts
N
N
N
Compound
M
6
7
8
2H Ni Zn
Scheme 1. The synthesis of the metal-free phthalocyanine and metallophthalocyanines (Ts = p-toluenesulphonyl).
acteristic of the proposed structure. The disappearance of
the C„N stretching vibration on the IR spectra of 5 sug-
gested the formation of compound 6. The MS mass spec-
trum of compound 6, which shows a peak at m/z = 2533
[M]+ support the proposed formula for this compound.
The metallophthalocyanines 7, 8 were synthesized in
moderate yield 28%, 32%, respectively. The metallopht-
halocyanines 7 and 8 were obtained from dicyano deriva-
tive 5 and corresponding anhydrous metal salts NiCl2
and Zn(CH3COO)2 respectively, by microwave irradiation
in 2-(dimethylamino)ethanol for 8 min. The IR spectra of
metallophthalocyanines 7 and 8 the disappearance of
strong C„N stretching vibration of 5 is an evidence for
the formation of metallophthalocyanines 7 and 8. The rest
of the IR spectra of metallophthalocyanines are very simi-
2.5
2
1.5
1
0.5
0
200
300
400
500
600
700
800
900
λ (nm)
Fig. 1. UV–vis spectra of compounds 6 (. . .), 7 (–Æ–Æ) and 8 (—-) in
pyridine.
1
lar to those of the metal-free phthalocyanine 6. In the H

2440
Z. Bıyıklıog˘lu et al. / Journal of Organometallic Chemistry 692 (2007) 2436–2440
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NMR spectra of these compounds are almost identical to
those of metal-free phthalocyanine 6. Also, it should be
1
mentioned that the other differences in the H NMR spec-
tra of metal-free phthalocyanine and metallophthalocya-
nines were the broad signals encountered in the case of
compounds 7 and 8, owing to the aggregation of planar
phthalocyanine molecules at the considerably high concen-
tration used for NMR measurements. They are in agree-
ment with the structural information. In the mass
spectrum of compounds 7 and 8, the presence of molecular
ion peaks at m/z = 2589 [M]+, 2597 [M+1]+respectively,
confirmed the proposed structures. We used a domestic
oven synthesis of compounds 6–9 including 300 W,
175 ꢁC as conditions.
In general, phthalocyanines show typical electronic
spectra with two strong absorption regions, one in the
UV region at about 300–500 nm related to the B band
and the other in the visible region at 600–700 nm related
to the Q band [31]. The split Q bands in 6, which are char-
acteristic for metal-free phthalocyanines were observed at
¨
¨
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_
¨
¨
¨
¨
k
max = 686 and 620 nm. These Q band absorptions broad
and non-symmetric because of aggregation [32,33]. Also
an increase in the concentration leads to aggregation which
is easily monitored by the position of the Q-band which is
shifted to shorter wavelengths, and to a decrease in molar
absorption coefficient [34–36]. The presence of strong
absorption bands in 6 in the near UV region at kmax = 431,
344, 321 and 288 nm also shows Soret region B bands
which have been ascribed to the deeper p–p* levels of
LUMO transitions.
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_
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k
max = 687 and 686 nm, with a weaker absorptions at 611
and 620 nm, respectively. The single Q bands in metallo
derivatives 7 and 8 are characteristic. This result is typical
of metal complexes of substituted and unsubstituted met-
allophthalocyanines with D4h symmetry [37]. Soret region
B band absorptions of nickel(II) phthalocyanine 7 and
zinc(II) phthalocyanine 8 were observed at kmax = 395,
305, 278 and 350, 310, 268 nm as expected, respectively.
_
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Acknowledgement
I. Gurol, V. Ahsen, J. Porphyrin. Phthalocyan. 4 (2000) 621.
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This study was supported by the Research Fund
of Karadeniz Technical University, Project No:
2002.111.002.6 (Trabzon–Turkey).
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