Derivatizable novel β-tetra 7-oxycoumarin-3-carboxylate substituted metallophthalocyanines: Synthesis and characterization

Article abstract of DOI:10.1016/j.poly.2010.06.016

In this study, a novel phthalonitrile, ethyl 7-(3,4-dicyanophenoxy) coumarin-3-carboxylate (1), was prepared and characterized. The metallophthalocyanines (3-6) were prepared by cyclotetramerization of 1 with the corresponding metal salts {Zn(OAc)₂

Full text of DOI:10.1016/j.poly.2010.06.016

Polyhedron 29 (2010) 2689–2695
Contents lists available at ScienceDirect
Polyhedron
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Derivatizable novel b-tetra 7-oxycoumarin-3-carboxylate substituted
metallophthalocyanines: Synthesis and characterization
*
Eyüp Dur, Mustafa Bulut
Marmara University, Department of Chemistry, Faculty of Art and Science, 34722 Göztepe, Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
In this study, a novel phthalonitrile, ethyl 7-(3,4-dicyanophenoxy)coumarin-3-carboxylate (1), was
prepared and characterized. The metallophthalocyanines (3–6) were prepared by cyclotetramerization
of 1 with the corresponding metal salts {Zn(OAc)2Á2H2O, Co(OAc)2Á4H2O, Cu(OAc)2, Ni(OAc)2Á4H2O} in
2-chloronaphthalene. Reaction of 3 with aqueous hydrochloric acid gave the coumarino-zincphthalocy-
anine (3a) carrying carboxyl groups at the 3-position of all the coumarin moieties. Treatment of com-
pound 3a with aqueous NaOH./AgNO3 or aqueous NaOH in N,N-dimethylformamide (DMF) gave the
expected silver (3c) or sodium (3d) salts, respectively. The four carboxylic groups in coumarino-zincpht-
halocyanine (3a) and the four carboxylate groups in 3d make the compounds have good solubility in
water. Heating of the acyl chloride derivative of 3 with morpholine in DMF yielded the corresponding
3-carboxymorpholinamide (3b). The newly prepared compounds, phthalonitrile and metallophthalocya-
nines, have been characterized by FT-IR, UV–Vis, MALDI-TOF and 1H NMR spectroscopies.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 21 January 2010
Accepted 17 June 2010
Available online 1 July 2010
Keywords:
Coumarin
Phthalocyanine
Aggregation
Zinc
Cobalt
Morpholine
1. Introduction
On the other hand, coumarins (2H-chromen-2-ones), belong to
a very large class of oxygen heterocycles found in nature [12].
Phthalocyanines (Pcs), fully-aromatic eight nitrogen containing
planar 18 -electron heterocyclic conjugated compounds, have
Compounds containing a coumarin moiety display a broad spec-
trum of biological activities such as antifungal [13], anticoagulant,
vasodilator, estrogenic, dermal, photosensitizing, sedative, hyp-
notic, analgesic, antimicrobial [14], anti-inflammatory, anti-HIV
[15] and anti-ulcer activities [16]. Coumarin and 7-hydroxycouma-
rins exhibit cytotoxic effects against the lung adenocarcinoma cell
lines KB [17]. Some coumarins show anti-clotting activity [18]. For
example, carbochromene (3-diethylaminoethyl-7-ethoxycarbonyl-
methoxy-4-methylcoumarin) is a potent specific coronary vasodi-
lator, used for many years in the treatment of angina pectoris
[19]. Moreover, coumarins are widely used as additives in food
and cosmetics [20], dispersed fluorescent, laser dyes and optically
brightening agents [21]. Coumarins can also be used for the syn-
thesis of other useful molecules such as Pcs [11,22]. Within the
class of 7-hydroxycoumarins that typically display favorable fluo-
rescence and laser properties, the derivatives that bear an addi-
tional carboxylate substituent at the 3-position have several
differentiating properties. A series of substituted coumarin-3-carb-
oxylatosilver (I) complexes have antimicrobial activity [23]. All of
the coumarin-silver complexes inhibit DNA synthesis [24]. Some
coumarin sodium salts influence the blood clotting time [25]. Mor-
pholine is a simple heterocyclic compound with a great industrial
importance. It can be used in the production of various pharmaceu-
ticals and pesticides [26]. 7-Hydroxycoumarins allow the binding
of this structure to a Pc via a phenoxy bond [27]. This covalent
binding should not affect significantly the biological activity of
p
been the subject of intense research [1]. Research is now focused
on the investigation of their conductive, catalytic, photocatalytic
and electrochromic properties when a simple functional unit (e.g.,
redox-active, photo-active, catalytic) is attached to the periphery
of the phthalocyanine core. Pcs have found application as dyes
and pigments [2]. Also many other applications have appeared re-
cently, including photodynamic therapy (PDT), gas sensors, solar
cell technology [3,4], optical read–write discs, increasing the octane
rate of petrol [4], Langmuir–Blodgett films and non-linear optics
[5]. A major disadvantage of Pcs and MPcs are their low solubility
in organic solvents or in water. It has been found that suitable func-
tional groups such as carboxyl, sulfonyl and quaternized ammo-
nium groups in the periferal benzene rings of the Pc structure can
improve the solubility in protic or non-protic solvents [6]. The
solubility of the Pcs bearing four coumarin entities in the periphery
has been increased after the cleavage of all four lactone rings
[7–10]. Families of functional/reactive Pcs have been an interesting
target for chemists for the development of further chemical
reactions on the Pc complexes [11].
* Corresponding author. Tel.: +90 216 3479641/1370; fax: +90 216 3478783.
E-mail addresses: mbulut@marmara.edu.tr, mustafabulut50@gmail.com (M.
Bulut).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.06.016

2690
E. Dur, M. Bulut / Polyhedron 29 (2010) 2689–2695
the coumarin moiety. The combined structure of the coumarin and
Pc may be a potential candidate molecule in the application of pho-
todynamic therapy [28]. In view of the biological importance of
both ethyl 7-hydroxycoumarin-3-carboxylate and Pcs, it is worth-
while to combine these two functional molecules into a single
compound via a synthetic methodology and to prepare and charac-
terize their soluble metallophthalocyanines, which may also exhi-
bit biological activities.
This study concerns the synthesis, characterization and struc-
tural investigation of b-tetra(ethyl 7-oxycoumarin-3-carboxyl-
ate)-substituted Zn(II), Co(II), Cu(II) and Ni(II) Pcs (3–6). In
addition, the carboxylate functional groups of coumarino-ZnPc
(3) were reacted with morpholine in boiling DMF, yielding 3-car-
boxymorpholinamide (3b). The same product was obtained via
an acyl chloride intermediate of 3. Also, the ethyl carboxylate sub-
stituents of 3 were hydrolyzed with aqueous hydrochloric acid to
prepare a hot water soluble coumarino-ZnPc carrying a carboxylic
acid group in position 3 of each coumarin (3a). Reaction of this
coumarino-ZnPc with aqueous sodium hydroxide/silver nitrate or
aqueous sodium hydroxide in DMF afforded the corresponding
water soluble 3-carboxylatosilver (3c) or 3-carboxylatosodium
(3d) salt, respectively. The ligand (1) and the complexes (3–6 and
3a–3d) were characterized using physico-chemical methods like
1H NMR spectroscopy, elemental analysis, mass, electronic and IR
spectral measurements.
2.1.2. General procedure for the synthesis of 2(3),9(10),16(17),23(24)-
tetrakis[ethyl 7-oxycoumarin-3-carboxylate]phthalocyaninato metal
derivatives (3–6)
A mixture of compound 1 (0.1 g, 0.27 mmol) and 0.025 mmol
metal salts [Zn(OAc)2Á2H2O 0.014 g, Co(OAc)2Á4H2O 0.016 g,
Cu(OAc)2 0.009 g, Ni(OAc)2Á4H2O 0.016 g] in 2-chloronaphthalene
(2 mL) was heated and stirred at 170 °C for 24 h under N2 in a
sealed glass tube. After cooling to room temperature, the resulting
green–blue mixture was precipitated by ethanol and filtered off.
The product was washed with water, hot ethanol, acetone and
diethyl ether, and then dried.
2.1.2.1. 2(3),9(10),16(17),23(24)-tetrakis[ethyl 7-oxycoumarin-3-car-
boxylate]phthalocyaninatozinc(II) (3). This is soluble in THF, DMF,
DMA and DMSO. Yield: 0.024 g (22%). M.p. > 300 °C 1H NMR
(DMSO): d, ppm 7.00–7.62 (12H, m, Pc-H), 6.86–7.72 (12H, m, phe-
nyl-H), 8.80 (4H, s, coum.-4H), 1.29–4.18 (20H, m, alkyl-H). FT-IR
(KBr)
1718 (–C@O), 1599–1466 (Ar, –C@C–), 1392–1211 (Ar–O–C),
1087, 1043, 941, 834, 745. UV–Vis kmax (nm) (log ) in DMF: 324
(4.78), 629 (4.38), 676 (4.97). MALDI-TOF ( -cyanohydroxycin-
namic acid,
-CHCA as matrix) m/z: 1507.67 [M+H]+. Anal. Calc.
m
max/(cmÀ1): 3061–3030 (Ar–H), 2921–2854 (aliphatic CH),
e
a
a
for C80H48N8O20Zn: C, 63.71; H, 3.18; N, 7.43. Found: C, 63.89; H,
3.36; N, 7.23%.
2.1.2.2. 2(3),9(10),16(17),23(24)-tetrakis[7-oxycoumarin-3-carbox-
ylic acid]phthalocyaninatozinc(II) (3a). A solution of 2(3),9(10),
16(17),23(24)-tetrakis[ethyl 7-oxycoumarin-3-carboxylate]phtha-
locyaninatozinc (II) (3) (0.030 g, 0.019 mmol) in DMF (4 mL) con-
taining water (1.42 mL) and concentrated hydrochloric acid (37%,
0.14 mL) was refluxed for 12 h. After cooling to room temperature,
the resulting mixture was precipitated by ice and collected by cen-
trifuge. Then, the product was washed with water to neutralize it,
and dried in a vacuum oven.
2. Experimental
2.1. Synthesis
Ethyl 7-hydroxycoumarin-3-carboxylate (2) was prepared by a
reported procedure [23]. The starting material, 4-nitrophthalonitri-
le, was synthesized by using the literature method [9]. The purities
of ethyl 7-hydroxycoumarin-3-carboxylate (2) and 4-nitro-1,2-
dicyanobenzene were tested in each step by TLC. Routine IR spectra
were recorded on a Shimadzu Fourier Transform FTIR-8300 infrared
spectrophotometer using KBr pellets. The electronic spectra were
monitored on a Shimadzu UV-2450 UV–Vis spectrophotometer.
1H NMR spectra were recorded on a Varian Unity Inova 500 MHz
NMR spectrophotometer using TMS as an internal reference at the
Gebze Institute of Technology. Elemental analysis was performed
by the Instrumental Analysis Laboratory of TUBITAK Ankara Test
and Analysis Laboratory. Mass spectra were performed on a Bruker
Daltonic Autoflex III MALDI-TOF spectrometer at Marmara
University.
This product is soluble in hot water, THF, DMF, DMA and DMSO.
Yield: 0.015 g (55%). M.p. > 300 °C. FT-IR (KBr) m
max/(cmÀ1): 3423–
3200 (carboxyl OH), 3074–3051 (Ar–H), 1712 (lactone, –C@O),
1600–1469 (Ar, –C@C–), 1395–1212 (Ar–O–C), 1120, 1091, 1045,
985, 836, 745. UV–Vis kmax (nm) (log e) in DMF: 331 (4.54), 615
(4.19), 673 (4.62). MALDI-TOF (a-CHCA as matrix) m/z: 1394
[M]+. Anal. Calc. for C72H32N8O20Zn: C, 61.95; H, 2.31; N, 8.04.
Found: C, 61.19; H, 2.23; N, 8.27%.
2.1.2.3. 2(3),9(10),16(17),23(24)-tetrakis[7-oxycoumarin-3-(morpho-
line-4-carbonyl)]phthalocyaninatozinc(II)
(3b). Compound 3a
(0.015 g, 0.01 mmol) was refluxed with thionyl chloride (2 mL)
for 3 h and then the mixture was distilled to remove residual thio-
nyl chloride. After cooling to room temperature, morpholin
(0.003 g, 0.004 mmol) was added and the mixture was refluxed
in dry DMF (2 mL) for 8 h. The resulting mixture was precipitated
by ice and the product was collected by centrifuge. Then, the prod-
uct was washed with water to neutralize and dried in a vacuum
oven.
2.1.1. Ethyl 7-(3,4-dicyanophenoxy)coumarin-3-carboxylate (1)
Ethyl 7-hydroxycoumarin-3-carboxylate (2) (1.00 g, 4.27 mmol)
and 4-nitro-1,2-dicyanobenzene (0.74 g, 4.27 mmol) were dis-
solved in dry DMF (100 mL), anhydrous K2CO3 (0.89 g, 6.41 mmol)
was added and the mixture was heated and stirred for 24 h under
nitrogen at 50–60 °C. The reaction mixture was treated with di-
luted HCl under ice cooling. The brown precipitate that formed
was filtered, washed with water to neutralize it, and dried. This so-
lid was soluble in THF (tetrahydrofurane), CHCl3 (chloroform),
DMF, DMA (dimethylacetamide) and DMSO (dimethylsulfoxide).
This product is soluble in THF, DMF, DMA and DMSO. Yield:
0.009 g (56%). M.p. > 300 °C. 1H NMR (DMSO-d6) d (ppm): 6.92–
7.92 (12H, m, Pc-H), 6.88–7.72 (12H, m, phenyl-H), 8.65 (4H, s,
coum-4H), 367–3.46 (32H, m, morpholine-H). FT-IR (KBr) mmax
/
Yield: 0.84 g (54%); m.p. 261–265 °C. FT-IR (KBr)
m
max/(cmÀ1):
(cmÀ1): 3091–3032 (Ar–H), 2960–2850 (aliphatic CH), 1711 (–
3053–2997 (Ar–CH), 2935–2911 (aliphatic CH), 2333 (C„N),
1737 (–C@O), 1593–1484 (Ar, –C@C–), 1243 (Ar–O–Ar), 1170,
1115, 1035, 843, 797, 772, 632, 522, 456. 1H NMR (DMSO-d6) d
(ppm): 8.82 (s, 1H), 8.22 (d, J = 8.5 Hz, 1H), 8.19 (d, J = 8.5 Hz,
1H), 8.00 (d, J = 2.5 Hz, 1H), 7.70 (dd, J = 9.0 Hz and 2.5 Hz, 1H),
7.64 (dd, J = 9.0 and 2.5 Hz, 1H), 7.29 (d, J = 1.5 Hz, 1H), 4.30 (q,
J = 7.0 Hz, 2H), 1.31 (t, J = 7 Hz, 3H). MALDI-TOF m/z: 396
C@O), 1604–1467 (Ar, –C@C–), 1363–1250 (Ar–O–C), 1113, 1021,
746, 636. UV–Vis kmax (nm) (log
e) in DMF: 334 (4.45), 638
(4.23), 670 (4.31). MALDI-TOF (a-CHCA as matrix) m/z: 1670
[M]+. Anal. Calc. for C88H60N12O20Zn: C, 63.26; H, 3.62; N, 10.06.
Found: C, 63.45; H, 3.32; N, 10.27%.
2.1.2.4. 2(3),9(10),16(17),23(24)-tetrakis[silver 7-oxycoumarin-3-car-
boxylate] phthalocyaninatozinc(II) (3c). A solution of compound 3a
[M+2H2O] +. UV–Vis kmax (nm) (log
e
) in DMF: 313 (4.47).

E. Dur, M. Bulut / Polyhedron 29 (2010) 2689–2695
2691
(0.024 g, 0.017 mmol) in DMF (1 mL) and sodium hydroxide
(2.76 mg, 0.069 mmol) in water (1 mL) was added to a solution
of silver (I) nitrate (11.7 mg, 0.069 mmol) in water (1 mL) over a
period of 30 min at room temperature, resulting in the formation
of a lighter green precipitate in comparison with 3a. The suspen-
sion was left to stir for 1 h and the resulting precipitate was iso-
lated by filtration. The resulting solid silver salt of 3a, was
washed with cold water and methanol. The solid was then dried
in the dark in a vacuum oven at 50 °C for 2 days.
of K2CO3 in dry DMF under a N2 atmosphere at 50–60 °C for one
day. The crude product was purified by silica gel column chroma-
tography using CHCl3 as the eluent, and the yield was 54%. The IR
spectrum of 1 exhibits an intense absorption band at 2233 cmÀ1
corresponding to the C„N stretching, and characteristic frequen-
cies at 3053 (Ar–H), 1737 (lactone –C@O), 1593 (
–C@C– for the lactone ring) and 1249 cmÀ1 (Ar–O–Ar). The alkyl
group (–CH2–CH3) gave intense absorptions at 2923–2898 cmÀ1
a,b-unsaturated
.
A comparison of the IR spectral data of coumarin 2 and 1 clearly
indicated the formation of 1 by the disappearance of the O–H bands
of ethyl 7-hydroxycoumarin-3-carboxylate (2) at 3420 cmÀ1 and by
the appearance of a new absorption at 2223 cmÀ1 for the nitrile
groups. In addition, in the 1H NMR spectrum of 1, the disappearance
of the resonance belonging to the phenolic O–H group at 11.3 ppm
confirmed the existence of the expected compound 1. The 1H NMR
spectrum of 1 also indicated aromatic protons at around 7.29–
8.22 ppm as multiplets and the signal of the proton of coumarin 1
at position 4 at 8.82 ppm as a singlet and the CH3–CH2– protons
in the ethoxyl group in the range 4.30–1.31 ppm as a triplet and a
quartet. In addition to these results, elemental analyses and mass
spectra confirmed the proposed structure.
The novel metallo-Pcs containing four ethyl 7-oxycoumarin-3-
carboxylate moieties (3–6) were obtained from the reaction of
the dicyano derivative (1) and the corresponding metal salts
{Zn(OAc)2Á2H2O, Co(OAc)2Á4H2O, Cu(OAc)2, Ni(OAc)2Á4H2O} in 2-
chloronaphthalene at 170 °C in a sealed glass tube, followed by
extraction with various solvents (acetone, acetonitrile, ethanol,
methanol and diethyl ether) using Soxhlet, resulted in the corre-
sponding tetra-coumarin substituted MPcs (3–6) with 19–32%
yields (Fig. 1). The newly synthesized bluish green metallo-Pc
products (3–6) gave a clear solution in DMSO, DMF and DMA due
to the polar ethyl carboxylate moieties at the 3-position of all cou-
marins at the periphery of phthalocyanine core, but they are insol-
uble in water. The hydrochloric acid-catalyzed hydrolysis of
coumarino-ZnPc (3) in boiling DMF furnished the corresponding
product 3a with four carboxylic acid groups at the 3-position of
all peripheral coumarin moieties with good yield (55%). The exis-
tence of carboxylic groups on the coumarin lactone rings was con-
firmed by IR spectra {3423–3200 (carboxyl OH), 1712 cmÀ1
(lactone –C@O)}.
This product is slightly soluble in hot water, THF, DMF, DMA
and DMSO. Yield: 0.020 g (64%). M.p. > 300 °C. FT-IR (KBr) mmax
/
(cmÀ1) 3668–3430 (br., carboxylate), 1682–1608 (br., lactone, –
C@O),1508–1437 (br., –C@C–). MALDI-TOF (a-CHCA as matrix)
m/z: 1821 [M]+. Anal. Calc. for C72H28Ag4N8O20Zn: C, 47.47; H,
1.55; N, 6.15. Found: C, 47.24; H, 1.71; N, 6.43%.
2.1.2.5. 2(3),9(10),16(17),23(24)-tetrakis[sodium 7-oxycoumarin-3-
carboxylate]phthalocyaninatozinc(II) (3d). A solution of compound
3a (0.022 g, 0.016 mmol) in DMF (1 mL) and sodium hydroxide
(2.8 mL, 10%) were stirred for 3 h in a sealed glass tube. Then,
the mixture was precipitated by ethanol. The resulting solid was
washed with methanol and dried in a vacuum oven at 50 °C for
1 day.
This product is soluble in water, THF, DMF, DMA and DMSO.
Yield: 0.019 g (81%). M.p. > 300 °C. FT-IR (KBr)
m
max/(cmÀ1):
3650–3440 (br., carboxylate), 1716 (br., –C@O). MALDI-TOF (a-
CHCA as matrix) m/z: 1482 [M]+. Anal. Calc. for C72H28N8Na4O20Zn:
C, 58.34; H, 1.90; N, 7.56. Found: C, 58.45; H, 1.56; N, 7.23%.
2.1.2.6. 2(3),9(10),16(17),23(24)-tetrakis[ethyl 7-oxycoumarin-3-car-
boxylate] phthalocyaninatocobalt(II) (4). This product is soluble in
THF, DMF, DMA and DMSO. Yield: 0.029 g (28%). M.p. > 300 °C.
FT-IR (KBr)
CH), 1718 (C@O), 1601–1404 (Ar, –C@C–), 1336–1230 (Ar–O–C),
119, 1092, 1056, 986, 835, 752. UV–Vis kmax (nm) (log ) in DMF:
m
max/(cmÀ1): 3071–3039 (Ar–H), 2971–2849 (aliphatic
e
313 (4.61), 615 (4.13), 660 (4.33). MALDI-TOF (a-CHCA as matrix)
m/z: 1501.21 [M+H]+. Anal. Calc. for C80H48N8O20Co: C, 64.05; H,
3.22; N, 7.47. Found: C, 64.29; H, 3.15; N, 7.34%.
2.1.2.7. 2(3),9(10),16(17),23(24)-tetrakis[ethyl 7-oxycoumarin-3-car-
boxylate] phthalocyaninatocopper(II) (5). This product is soluble in
DMF, DMA and DMSO. Yield: 0.020 g (19%). M.p. > 300 °C. 3058–
3034 (Ar–H), 2925–2875 (aliphatic CH), 1718 (–C@O), 1603–
1467 (Ar, –C@C–), 1350–1231 (Ar–O–C), 1092, 987, 936, 839,
In the 1H NMR spectra of 3a, the carboxy proton was not ob-
served due to its exchange with solvent. Compound 3a was not
only soluble in alkaline water but also in hot water alone. In con-
tinuation of our interest on the synthesis and reactions on couma-
rin at the periphery of coumarino-Pcs, we reacted 3a with aqueous
NaOH or aqueous NaOH/AgNO3 in boiling DMF, aiming to synthesis
new water-soluble tetra-coumarin substituted MPc derivatives
which might have enhanced biological activities. The silver salt
(3c) is slightly soluble in hot water and is soluble in polar protic or-
ganic solvents, whilst the sodium salt (3d) is soluble in cold water
and polar organic solvents.
The coumarin substituents with ethyl carboxylate at the periph-
ery of the Pcs bring out numerous possibilities for binding with dif-
ferent nucleophiles. Treatment of compound 3 or its acyl chloride
derivative (not isolated) with the morpholine nucleophile in boiling
DMF afforded the corresponding 3-carboxymorpholinamide deriv-
ative (3b). The spectroscopic characterization of the newly synthe-
sized ligand 1 and Pcs (3–6, 3a–3d) included FT-IR, UV–Vis, MALDI-
TOF and 1H NMR investigations. The results were in accordance
with the proposed structures. The results of the elemental analyses
for carbon, hydrogen, nitrogen and the gravimetric methods for
metals were consistent with the proposed structures.
747. UV–Vis kmax (nm) (log
e) in DMF: 324 (4.88), 614 (4.49), 670
(4.58). MALDI-TOF (
a
-CHCA as matrix) m/z: 1504 [M]+. Anal. Calc.
for C80H48N8O20Cu: C, 63.85; H, 3.22; N, 7.45. Found: C, 63.58; H,
3.43; N, 7.54%.
2.1.2.8. 2(3),9(10),16(17),23(24)-tetrakis[ethyl 7-oxycoumarin-3-car-
boxylate] phthalocyaninatonicke(II) (6). This product is soluble in
DMF, DMA and DMSO. Yield: 0.034 g (32%). M.p. > 300 °C. 3070–
3047 (Ar–H), 2918–2857 (aliphatic CH), 1711 (–C@O), 1593–
1412 (Ar, –C@C–), 1278–1249 (Ar–O–C), 1163, 1121, 1094. UV–
Vis kmax (nm) (log
MALDI-TOF (
-CHCA as matrix) m/z: 1499 [M]+. Anal. Calc. for
80H48N8O20Ni: C, 64.06; H, 3.23; N, 7.47. Found: C, 64.21; H,
3.37; N, 7.64%.
e) in DMF: 284 (4.81), 613 (4.21), 663 (4.35).
a
C
3. Results and discussion
The ligand, ethyl 7-(3,4-dicyanophenoxy)coumarin-3-carboxyl-
ate (1) was prepared by a base catalyzed nucleophilic aromatic ni-
tro displacement reaction between 4-nitro-1,2-dicyanobenzene
and ethyl 7-hydroxycoumarin-3-carboxylate (2) in the presence
Cyclotetramerization of the dinitrile 1 to the MPcs (3–6) was
confirmed by the disappearance of the sharp C„N vibration at
2333 cmÀ1. This is an evidence for the IR-spectra of the metallo-
Pcs (3–6). All were very similar and showed absorption peaks at

2692
E. Dur, M. Bulut / Polyhedron 29 (2010) 2689–2695
Fig. 1. Synthetic route to ethyl 7-(3,4-dicyanophenoxy)coumarin-3-carboxylate (1) and the metallophthalocyanines (3–6, 3a–3d).
1118–1120, 1092–1093, 1069–1070, 945–950, 870–873 and 752–
756 cmÀ1, which may be assigned to the phthalocyanine skeletal
Also, a close investigation of the UV–Vis spectra of the phthalo-
cyanines (3a–3d) confirmed the proposed structures. The elec-
tronic absorption data of all these phthalocyanines have been
measured in DMF or DMSO at a concentration of 1 Â 10À5 mol LÀ1
and the results are presented in Fig. 3. The compounds showed
characteristic absorptions in the Q band region at 676 nm for 3,
660 nm for 4, 670 nm for 5, 663 nm for 6. The UV–Vis spectra of
the coumarino-ZnPc depended on its concentration, the B band re-
gion was observed around 338–350 nm in DMF. The coumarins
show high absorption in the near UV range around 310–346 nm
[11,22,29]. After Pc formation, four 7-oxycoumarin-3-carboxylate
groups are present in each Pc molecule, so the B band absorption
intensity can probably be increased compared to that of the Pc core
alone. The absorption of (3–6) and (3a–3d) can be carelessly
vibrations. The ester stretching bands and the
a,b-unsaturated –
C@C– (lactone ring) bands in the FT-IR spectra of all the coumari-
no-Pcs (3–6, 3a–3d) at ca. 1738 and 1640 cmÀ1 are evidences for
the formation of coumarino-Pcs.
The mass spectra of 3–6 confirmed the proposed structures. The
mass spectral studies by the MALDI-TOF technique on the newly
synthesized compounds identified peaks at m/z: 1507.67 [M+H]+
for 3 (Fig. 2), 1501.21 [M+H]+ for 4, m/z: 1504 [M]+ for 5, m/z:
1499 [M]+ for 6. The values of the molecular ions show good agree-
ment with the calculated values of all the metallo-Pcs (3–6) in the
presence of
in THF) as a matrix.
a
-cyano-4-hydroxycinnamic acid (CHCA) (20 mg mLÀ1

E. Dur, M. Bulut / Polyhedron 29 (2010) 2689–2695
2693
Fig. 2. Mass spectrum of 3.
Fig. 4. Absorbtion spectra of 3b in DMF with increasing concentrations, a–e;
Fig. 3. Absorbtion spectra of 3–6 in DMF.
1 Â 10À6–8 Â 10À6 mol LÀ1
.
named as only the B band of the Pc core around 340 nm; this also
covers the absorption of the coumarin units. There were also char-
acteristic shoulders at the slightly higher energy side of the Q band
for coumarino-ZnPc (3). The aggregation of phthalocyanine mole-
cules results mainly from p–p* interactions between the p electron
clouds of adjacent Pc macrocycles [30]. Some functional groups in
Pc molecules enable the formation of aggregates, which results
from additional specific interactions such as hydrogen bonding in
phthalocyanines containing carboxylic groups [31], esters [11] or
alkylamides [32]. The UV spectra of (3–6) and (3a–3d) in DMF
showed dimeric behaviour, evidenced by a broad Q band typical
of metallo-Pc complexes. The shift to lower wavelengths corre-
sponds to H-type aggregates of the Pc core. The coumarins can also
build H-type aggregations at carboxyl groups. On the other hand,
the lactone carbonyl of coumarins can coordinate metal cations
such as Cu2+, Mn2+, Ni2+ and Co2+ [24,33–35]. Through the coordi-
nation of the lactone carbonyl, the metallo-Pcs displayed aggrega-
tion (Fig. 3). Compound 3d, with a morpholine moiety at the 3-
position of all the coumarin substituents, displayed aggregation
with increasing concentrations (Fig. 4). The carboxylic groups in
Pc 3a make the compound very soluble in hot water. The UV–Vis
spectra of 3a (1 Â 10À6–8 Â 10À6 mol LÀ1) indicates the effect of
increasing concentration in DMF (Fig. 5). At the beginning, the
intensities of the Q and B bands are approximately equal to each
other. As the concentration of 3a is increased, the monomer Q band
Fig. 5. Absorbtion spectra of 3a in DMF with increasing concentrations, a–e;
1 Â 10À6–8 Â 10À6 mol LÀ1
.
becomes higher in intensity as compared with the dimer Q band.
This clearly suggests that the band with the higher energy corre-
sponds to the aggregated species. The coumarino-ZnPc (3a) also
aggregates in aqueous solutions. The B band is more intense than
the Q band because of the absorption contribution of the coumarin
moiety peripherally substituted on the Pc.

2694
E. Dur, M. Bulut / Polyhedron 29 (2010) 2689–2695
Fig. 9. Absorbtion spectra of 3c in DMSO showing aggregation tendency by
Fig. 6. Absorbtion spectra of 3d in DMSO showing aggregation tendency by
increasing the concentration, a–e; 1 Â 10À6–8 Â 10À6 mol LÀ1
.
increasing the concentration, a–e; 1 Â 10À6–8 Â 10À6 mol LÀ1
.
Broadened bands appear in the Q region for concentrations ranging
from 1 Â 10À6 to 8 Â 10À6 mol LÀ1 in DMSO or in water. There are
two absorption maxima: dmax = 635 and 680 nm, which are attrib-
uted to 3d aggregates and monomers, respectively. The intensity of
the monomer band gradually decreases with increasing concentra-
tion, while the intensity of the aggregate band increases. The spec-
tra in DMSO and in water showed that complex 3d aggregates
more strongly in water than in DMSO (Fig. 8). The silver salt 3c also
shows similar aggregation behaviour in DMSO (Fig. 9) to 3d, but
not to the same extent because of the covalent character of the sil-
ver complex (3c) compared with the sodium salt (3d). The couma-
rino-ZnPcs (3a and 3d) are soluble in water, which is important in
aqueous biological systems and practical applications.
Fig. 7. Absorbtion spectra of 3d in water with increasing concentrations; 1 Â 10À6
–
4. Conclusions
8 Â 10À6 mol LÀ1
.
In conclusion, we have designed, synthesized and characterized
in polar organic solvents soluble metallo (Zn, Co, Cu, Ni) Pc deriv-
atives derived from phthalonitrile with an ethyl 7-hydroxyl-3-car-
boxylate substituent. The acidic hydrolysis of the lactone opening
reaction of the coumarin moiety gave a water soluble coumari-
no-ZnPc bearing carboxylic acid groups at 3-position of each cou-
marin. Its silver salt is slightly soluble in hot water, but the
sodium salt has good solubility in cold water. This makes such no-
vel chromophore materials attractive candidates in applications
such as PDT as photosensitizers for biological purposes. We also
showed that the carboxy functional groups at the periphery of
the Pcs have considerable value in the synthesis of Pcs bearing car-
boxymorpholinamide groups.
Acknowledgements
We are thankful to the Scientific and Research Council of Turkey
(TÜBITAK) (107T347 and 108T623).
Fig. 8. Absorbtion spectra of 3d in DMSO (1 Â 10À5 mol LÀ1
(1 Â 10À5 mol LÀ1).
)
and water
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