Synthesis, characterization, spectroscopic and electrochemical properties of phthalocyanines substituted with four 3-ferrocenyl-7-oxycoumarin moieties

Article abstract of DOI:10.1016/j.jorganchem.2011.02.029

The synthesis, spectroscopic and electrochemical properties of the tetra-(3-ferrocenyl-7-oxycoumarin)-substituted zinc (II) and cobalt (II) phthalocyanines (3 and 4) are reported for the first time. The synthesis of novel 3-ferrocenyl-7-hydroxycoumarin (1

Full text of DOI:10.1016/j.jorganchem.2011.02.029

Journal of Organometallic Chemistry 696 (2011) 1868e1873
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterization, spectroscopic and electrochemical properties of
phthalocyanines substituted with four 3-ferrocenyl-7-oxycoumarin moieties
,
Meryem Çamur a, A. Aslı Esenpınar a, A. Rıza Özkaya b, Mustafa Bulut b
*
a Kırklareli University, Department of Chemistry, 39100 Kırklareli, Turkey
b Marmara University, Department of Chemistry, 34722 Goztepe-Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis, spectroscopic and electrochemical properties of the tetra-(3-ferrocenyl-7-oxycoumarin)-
substituted zinc (II) and cobalt (II) phthalocyanines (3 and 4) are reported for the first time. The synthesis
of novel 3-ferrocenyl-7-hydroxycoumarin (1) was performed according to Perkin reaction, and the
ligand, 7-(3,4-dicyanophenoxy)-3-ferrocenylcoumarin (2), was synthesized by the reaction of 3-ferro-
cenyl-7-hydroxycoumarin with 4-nitrophthalonitrile in the presence of K2CO3 as the base in dry dime-
thylformamide. The preparation of the corresponding zinc (II) and cobalt (II) metallo phthalocyanines (3
Received 6 January 2011
Received in revised form
17 February 2011
Accepted 23 February 2011
Keywords:
Phthalocyanine
and 4) substituted with 3-ferrocenyl-7-oxycoumarin moieties at b-positions of the phthalocyanine ring
was achieved by the cyclotetramerization of the coumarin ligand (2) with relevant metal(II) acetates in
dry 2-dimethylaminoethanol. The new compounds have been characterized by elemental analyses, FT-IR,
1H NMR, Mass and electronic spectroscopy. The fluorescence property of the zinc metallo phthalocyanine
(3) is strongly affected by the presence of ferrocenyl moiety. The ferrocenyl moieties were very efficient
in quenching the excited state of 3, which show very poor fluorescent intensity. The electrochemical
properties of the complexes were also investigated by cyclic and differential pulse voltammetry tech-
niques in non-aqueous medium. It was found that the redox-active ferrocene substituents are reduced
concurrently at one potential.
Coumarin (2H-1-benzopyran-2-one)
Ferrocene
Fluorescence
Electrochemistry
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
interest in various areas [15], like asymmetric catalysis, non-linear
optics [16] and electrochemistry [17] due to the quasi-reversible
Phthalocyanines (Pcs) have been an area of increasing research
for several years, due to their applicability in a variety of fields, such
as liquid crystals, semiconductors, non-linear optics and electron
transfer, among others. Pcs are compounds of special interest for
their unique redox and photophysical properties [1e3]. Many
derivatives of these compounds can be prepared not only by
changing the nature of the central metal atom, but also by formally
fusing additional aromatic rings to the central core; or by forming
planar or linear groups [4]. Pc-based multicomponent systems have
been explored, including porphyrins [5], ferrocenes [6,7], crown
ethers [8,9], tetrathiafulvalenes, oligopyridylemetal complexes,
dendrimers, and C60 [10e12]. Furthermore, Pcs have long been
known to undergo electron transfer reactions, both to and from
their excited states, and strong electron donors such as ferrocene
are able to quench the Pc fluorescence by intermolecular electron
transfer [13,14]. Many ferrocene derivatives are of considerable
oxidation of iron(II).
Coumarin (2H-1-benzopyran-2-one) and its derivatives are
a group of lactones derived from o-hydroxycinnamic acids: alter-
nately stated, a coumarin ring system is formed by the fusion of
a benzene and a 1,2-pyrone ring [18]. Coumarins belong to an
important class of fluorescent compounds having interesting
photophysical properties and a wide range of applications in laser
dyes [19], photosensitizers [20], pesticides [21] etc. Materials con-
taining a coumarin component are useful in many fields due to
their characteristics of high emission yield, excellent photostability
and extended spectral range, such as fluorescent images [22,23],
non-linear optical materials [24], liquid crystals [25] and fluores-
cent labels for fluorescence energy transfer experiments [26].
7-Hydroxy-4-methylcoumarin (7-HMC) is a derivative of coumarin,
who’s ground- and excited state, photophysical properties have
been the subject of many studies. It is used as an important fluo-
rescent indicator for pH measurements [27e31].
Recently, we have successfully prepared Pcs substituted with
coumarin skeleton, which exhibited excellent fluorescence prop-
erties with quantum yield of almost unity [32e34]. In this paper,
* Corresponding author. Tel.: þ90 216 3479641/1370; fax: þ90 216 3478783.
E-mail address: mbulut@marmara.edu.tr (M. Bulut).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.02.029

M. Çamur et al. / Journal of Organometallic Chemistry 696 (2011) 1868e1873
1869
our aim has been to prepare and characterize novel zinc (II) (3) and
cobalt (II) (4) metallo Pcs substituted with 3-ferrocenyl-7-oxy-
coumarin. We also investigated the change of fluorescence prop-
erties of 3 which is substituted with ferrocene moiety at the
3-position of coumarin. The electrochemical properties of the
complexes were also presented.
mixture was poured into 150 mL iceewater. The resulting solid was
collected by filtration and washed with water. The crude product
was purified on a silica gel column using chloroform as eluent.
Yield: 1.05 g (86%); m.p.: 250 ꢀC. Anal. calcd. for C27H16N2O3Fe: C,
68.64; H, 3.39; N, 5.93%. Found: C, 68.86; H, 3.14; N, 5.82. UVevis
(CHCl3): lmax, nm (log e
) 495 (3.26, Fc), 335 (4.27, coumarin). 1H
NMR (500 MHz; CDCl3): dH, ppm 7.78 (dd, 1H, AreH), 7.75 (s, 1H,
lactone 4eH), 7.55 (d, J ¼ 8Hz, 1H, AreH), 7.33 (dd, 1H, AreH), 7.37
(d, J ¼ 3Hz, 1H, AreH), 7.04 (d, J ¼ 3Hz, 1H, AreH), 6.97 (d, J ¼ 8Hz,
2. Experimental
2.1. Materials and equipment
1H, AreH), 4.97 (s, 2H, Fc), 4.46 (s, 2H, Fc), 4.16 (s, 5H, Fc). IR n
(cmꢁ1): 3040e3090 (AreH), 2200 (eC^N), 1770 (C]O lactone),
1475e1600 (C]C), 1250 (CeOeC). MS (MALDI-TOF): m/z 472 [M]þ,
473 [M þ 1]þ.
Infrared Spectra (IR) were recorded on a Shimadzu FTIR-8300
Fourier Transform Infrared Spectrophotometer using KBr pellets,
electronic spectra on a Shimadzu UV-2450 UVeVISIBLE Spectro-
photometer. Elemental analyses were performed by the Instru-
mental Analysis Laboratory of the TUBITAK Marmara Research
Centre. 1H NMR spectra were recorded on a Varian Mercury-VX
500 MHz spectrometer using TMS as an internal standard. Mass
spectra were performed on a Bruker Autoflex III MALDI-TOF spec-
trometer. A 2,5-dihydroxybenzoic acid (DHB) (20 mg/mL in THF)
matrix was used. MALDI samples were prepared by mixing the
complex [2 mg/mL in tetrahydrofuran (THF)] with the matrix
2.2.3. 2(3),9(10),16(17),23(24)-Tetrakis(3-ferrocenyl-7-
oxycoumarin)phthalocyaninato zinc (II) (3)
A mixture of 2 (0.100 g, 0.212 mmol), Zn(CH3COO)2.2H2O
(0.0116 g, 0.053 mmol) in 2-dimethylaminoethanol (1.5 mL) was
heated and stirred at 155 ꢀC for 6 h under N2 atmosphere. After
cooling to room temperature, the reaction mixture was precipitated
by the addition of methanol (5 mL) and green precipitate was
filtered off. It was treated with boiling ethanol, methanol, ethyl
acetate and acetone several times to dissolve the unreacted started
materials and decomposition product. Furthermore this product
was purified with preparative thin layer chromatography using
(silicagel) THF-MeOH (10:1) solvent system. Yield: 0.047 g (45%);
m.p.: >300 ꢀC. Anal. calcd. for C108H64N8O12Fe4Zn: C, 66.36; H, 3.28;
N, 5.74%. Found: C, 66.45; H, 3.21; N, 5.76. UVevis (DMF): lmax, nm
solution (1:10 v/v) in a 0.5 mL Eppendorf micro tube. Finally, 1 mL of
this mixture was deposited on the sample plate, dried at room
temperature and then analyzed. Fluorescence excitation and
emission spectra were recorded on a HITACHI F-7000 Fluorescence
Spectrophotometer using 1 cm pathlength cuvettes at room
temperatures. 4-Nitrophthalonitrile was prepared according to the
reported procedure [35] and ferroceneacetic acid was purchased
from Aldrich Chemical Company, and was used as purchased. All
reagents and solvents were of reagent-grade quality obtained from
commercial suppliers. All solvents were dried, purified and stored
over molecular sieves (4 Å). The homogeneity of the products was
tested in each step using TLC (SiO2).
(log e) 675 (4.83), 606 (4.05), 485 (3.88), 343 (4.68). IR n
(cmꢁ1):
3050e3080 (AreH), 1760 (C]O lactone), 1440e1600 (C]C), 1280
(CeOeC). MS (MALDI-TOF): m/z 1953 [M]þ, 1954 [M þ 1]þ, 1955
[M þ 2]þ, 1956 [M þ 3]þ, 1957 [M þ 4]þ.
2.2.4. 2(3),9(10),16(17),23(24)-Tetrakis(3-ferrocenyl-7-
oxycoumarin)phthalocyaninato cobalt (II) (4)
2.2. Synthesis
Compound 4 was prepared and purified according to the
procedure described for 3, starting from 0.100 g (0.212 mmol) 2,
0.0132 g (0.053 mmol) Co(CH3COO)2$4H2O and 2-dimethylami-
noethanol (1.5 mL). Yield: 0.052 g (51%); m.p.: >300 ꢀC. Anal. calcd.
for C108H64N8O12Fe4Co: C, 66.56; H, 3.29; N, 5.75%. Found: C, 66.24;
2.2.1. 3-Ferrocenyl-7-hydroxycoumarin (1)
Ferroceneacetic acid (0.900 g, 3.688 mmol), 2,4-dihydrox-
ybenzaldehyde (0.509 g, 3.688 mmol), sodium acetate (1.2095 g,
14.75 mmol) and anhydrous acetic anhydride (8 mL) were heated
for 9 h at 160 ꢀC. After cooling to room temperature, water was
added and the mixture stirred overnight. The resulting solid,
7-acetoxy-3-ferrocenylcoumarin, was filtered, washed with water.
The crude product was suspended in methanol. A 10% aq HCl
solution was added to adjust the pH to 3 and ensuing mixture was
heated and stirred at 65 ꢀC for 24 h under vacuum. The product,
3-ferrocenyl-7-hydroxycoumarin, was washed with water after the
removal of methanol and dried. The compound was purified on
a silica gel column using chloroform as eluent. Yield: 0.945 g (66%);
m.p.:>300 ꢀC. Anal. calcd. for C19H14O3Fe: C, 65.90; H, 4.05%. Found:
H, 3.12; N, 5.50. UVevis (DMF): lmax, nm (log
e) 661 (4.69), 598
(4.24), 489 (3.88), 334 (4.88). IR
n
(cmꢁ1): 3065e3075 (AreH), 1754
(C]O lactone), 1448e1603 (C]C), 1284 (CeOeC). MS (MALDI-
TOF): m/z 1947 [M]þ, 1948 [M þ 1]þ.
2.3. Electrochemistry
The cyclic voltammetry, differential pulse voltammetry, and
controlled potential chronocloumetry (CPC) measurements were
carried out with a Princeton Applied Research Model Versostat II
potentiostat/galvanostat controlled by an external PC and utilizing
a three-electrode configuration at 25 ꢀC. The working electrode was
a Pt plate with a surface area of 0.10 cm2. The surface of the working
electrode was polished with H2O suspension of Al2O3 before each
run. The last polishing was done with a particle size of 50 nm. A Pt
wire served as the counter electrode. Saturated calomel electrode
(SCE) was employed as the reference electrode and separated from
the bulk of the solution by a double bridge. Electrochemical grade
tetrabutylammonium perchlorate (TBAP) in extra pure DMSO was
employed as the supporting electrolyte at a concentration of
0.10 mol dmꢁ3. High purity N2 was used for deoxygenating the
solution at least 20 min prior to each run and to maintain a nitrogen
blanket during the measurements. For CPC studies, Pt gauze
working electrode (10.5 cm2 surface area), Pt wire counter
C, 65.86; H, 3.99. UVevis (CHCl3): lmax, nm (log
e) 468 (3.28,
ferrocene, Fc), 344 (4.25, coumarin). 1H NMR (500 MHz; DMSO): dH
,
ppm 9.89 (s, 1H, OH), 8.12 (s, 1H, lactone 4eH), 7.50 (d, J ¼ 8Hz, 1H,
AreH), 6.76 (dd, 1H, AreH), 6.70 (d, J ¼ 3Hz, 1H, AreH), 4.94 (s, 2H,
Fc), 4.36 (s, 2H, Fc), 4.07 (s, 5H, Fc). IR
n
(cmꢁ1): 3200 (OH),
3015e3060 (AreH), 1700 (C]O lactone), 1450e1620 (C]C). MS
(MALDI-TOF): m/z 346 [M]þ, 347 [M þ 1]þ.
2.2.2. 7-(3,4-Dicyanophenoxy)-3-ferrocenylcoumarin (2)
3-Ferrocenyl-7-hydroxycoumarin (1) (0.900 g, 2.60 mmol) was
dissolved in 20 mL of dry DMF and 4-nitrophthalonitrile (0.450 g,
2.60 mmol) was added. After stirring for 10 min finely ground
anhydrous K2CO3 (0.542 g, 2.60 mmol) was added and the reaction
mixture was stirred at 50 ꢀC for 48 h under vacuum. Then the

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M. Çamur et al. / Journal of Organometallic Chemistry 696 (2011) 1868e1873
electrode separated by a glass bridge, and SCE as a reference elec-
trode were used.
4 at
4.94, 4.36 and 4.07 ppm as singlets. In the 1H NMR analysis of 2 in
CDCl3, the proton of coumarin at position 4 appeared as a singlet at
7.75 ppm, the aromatic protons as dublets at 6.97e7.78 ppm,
ferrocenyl protons as singlets at 4.97, 4.46 and 4.16 ppm. The
d 8.12 ppm as a singlet. The ferrocenyl protons were observed at
d
d
d
3. Results and discussion
d
MALDI-TOF mass spectra of compounds 1 and 2 confirmed the
proposed structures; molecular ions were easily indentified at m/z:
346 [M]þ for 1 and m/z: 472 [M]þ for 2.
In the FT-IR spectra of 3 and 4, the lactone C]O bands of the
coumarins and aromaticC]C bandsappearat1760,1440e1600 cmꢁ1
for 3 and 1754, 1448e1603 cmꢁ1 for 4, respectively. In the mass
spectra of compounds 3 and 4, the presence of molecular ion peaks at
m/z: 1953 [M]þ (Fig. 1) and 1947 [M]þ respectively, confirmed the
proposed structures.
The ground state electronic spectra of the Pc complexes showed
characteristic absorption in the Q band region at 675 nm for 3 and
661 nm for 4. The B band region was observed at 343 nm for 3 and
334 nm for 4. The spectra showed monomeric behavior evidenced
by a single Q band, typical of metalled Pc complexes for 3 and 4 in
DMF which depict the monomeric nature of these complexes
(Fig. 2). It was found that the Q band of 3 is red shifted (14 nm) as
compared with that of 4 in DMF. A broad absorption band at ca.
485 nm originates from the presence of ferrocene units on the
periphery. Due to the ferrocenyl moieties, the Q band (675 nm in
DMF) is substantially blue-shifted (14 nm) by comparing with the 2
(3),9(10),16(17),23(24)-tetrakis(7-oxy-4-methylcoumarin)phthalo-
cyaninato zinc(II) (5) (689 nm in DMF) (Fig. 3) [37].
The synthetic procedures of the 3-ferrocenyl-7-oxycoumarin
substituted phthalonitrile derivatives (2) and Pc complexes (3 and
4) are given in Scheme 1. 3-Ferrocenyl-7-hydroxycoumarin (1)
was synthesized by the reaction of ferroceneacetic acid with
2,4-dihydroxybenzaldehyde via Perkin reaction [36]. 7-(3,4-Dicyano-
phenoxy)-3-ferrocenylcoumarin (2) was synthesized through base-
catalyzed aromatic nitro displacement of 4-nitrophthalonitrile with 1
using K2CO3 as the base in dry DMF. The reaction was carried out at
50 ꢀC for 48 h under N2 atmosphere. Zinc(II) and cobalt(II) metallo Pcs
(3 and 4) were synthesized by reaction of 2 with Zn(CH3COO)2.2H2O
and Co(CH3COO)2$4H2O in 2-dimethylaminoethanol for 6 h at 155 ꢀC
under N2 atmosphere. The Pc complexes were purified by preparative
thin layer chromatography using THF-MeOH (10:1) solvent system.
The structures of the target compounds were confirmed using
elemental analysis, FT-IR, 1H NMR, UVeVis and MALDI-TOF methods.
The analyses are consistent with the predicted structures.
Comparison of the FT-IR spectral data clearly indicated the
formation of compound 1 by the appearance of new absorption
bands at 3200 cmꢁ1 (OH), 3015e3060 cmꢁ1 (AreH), 1700 cmꢁ1
(C]O lactone) and 1450e1620 cmꢁ1 (C]C). After conversion of the
1 into dinitrile derivative (2) the broad peak for the eOH band
disappeared and the characteristic vibrations of the eC^N appear
at 2200 cmꢁ1. 1H NMR spectrum of 1 indicated the eOH proton at
Fig. 4 shows the fluorescence emission spectra for compounds 3
and 5. The Pc 4 does not show fluorescence at excitationwavelength.
In DMF, emission peaks were observed at 689 nm for 3 and 692 nm
d
9.89 ppm as a singlet, the aromatic protons at the range of
d
6.70e7.50 ppm as doublets and the proton of coumarin at position
1)
Ac2O, CH3COONa
N2,160-170oC
HO
O
O
COOH
HO
OH
Fe
2) HCl / MeOH
60-65oC
2,4-Dihydroxybenzaldehyde
CHO
1
Fe
Ferroceneacetic acid
4-Nitrophthalonitrile
DMF
K2CO3
NC
NC
O
O
O
Fe
O
O
Fe
2
O
2-Dimethylaminoethanol,155ºC
3
)
Zn(CH3COO)2.2H2O (for
4
)
Co(CH3COO)2.4H2O (for
O
N
N
N
O
Fe
O
M
N
N
N
O
Fe
O
N
N
O
O
M: Zn (3), Co (4)
O
O
Fe
Scheme 1. Synthetic procedures of 3-ferrocenyl-7-oxycoumarin substituted phthalonitrile derivatives (1 and 2) and Pc complexes (3 and 4).

M. Çamur et al. / Journal of Organometallic Chemistry 696 (2011) 1868e1873
1871
Fig. 1. Mass spectrum of zinc(II) metallo Pc (3).
for 5. The excitation spectra were similar to absorption spectra and
both were mirror images of the fluorescence spectra [38]. The
fluorescence property of coumarin chromophore system is signifi-
cantly altered by appropriate substituents at the 3- and the 7-posi-
tion. Electron donors such as amino, hydroxyl and methoxy groups
at the 7-position and electron acceptor heterocyclic rings such as
benzthiazole, benzoxazole and benzimidazole at the 3-position
impart pronounced bathochromicity and strong fluorescence [39].
Fluorescence property of the 7-oxy-4-methylcoumarin substituted
Pc (5) is strongly affected by the presence of ferrocenyl substituents.
Pc 5 possesses high fluorescence intensity, while the ferrocene-
substituted Pc 3 shows very poor fluorescent intensity. In fact, it has
been reported that covalently linked ferrocenes substantially
quenched the fluorescence emission of other chromophores, for
example; porphyrins, through an intramolecular electron-transfer
process [40,41]. Our fluorescence studies indicated that the
phthalocyanine fluorescence was quenched to a greater extent in
phthalocyanineecoumarineferrocene conjugates because of photo-
induced electron transfer from ferrocene to coumarin substituted
phthalocyanine.
first oxidation processes of 3 was achieved, and the time integration
of the electrolysis current was recorded with the controlled
potential coulometry studies. The charge, Q, at the end of elec-
trolysis was calculated using the current-time response of solution
and Faraday’s law was used to estimate the number of electrons
transferred. The number of electrons was found to be one for the
mentioned redox processes of 3. The comparison of the peak
currents of these processes with those of others suggested that the
number of electrons is also one for the other redox processes except
the second oxidation couple of 3. Figs. 5 and 6 show typical cyclic
and differential pulse voltammograms of 3 and 4, respectively, in
DMSO containing TBAP. The peak currents of the second oxidation
couple (O2) of 3 are approximately four times those of its reduction
couples (R1eR4) and first oxidation couple (O1). The situation was
similar for the comparison of the peak currents of the first oxida-
tion couple of 4 with those of its reduction couples (R1eR3),
H3C
The solution redox properties of the Pc complexes 3 and 4 were
studied using cyclic voltammetry, differential pulse voltammetry
and controlled potential chronocoulometry in DMSO on platinum
electrode. Complete electrolysis of each Pc solution at the working
electrode at a suitable constant potential for the first reduction and
O
O
O
O
N
N
O
N
CH3
Zn
N
N
O
O
H3C
N
O
N
N
O
(5)
O
O
O
CH3
Fig. 2. Electronic spectra of zinc(II) and cobalt(II) metallo Pcs (3 and 4) in DMF,
Concentration: 1.0 ꢂ 10ꢁ5 M.
Fig. 3. 2(3),9(10),16(17),23(24)-Tetrakis(7-oxy-4-methylcoumarin)phthalocyaninato
zinc(II) (5).

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M. Çamur et al. / Journal of Organometallic Chemistry 696 (2011) 1868e1873
TBAP/DMSO, the complex 4 undergo two oxidations, the first one
with reversible transfer of one electron and the second one with
quasi-reversible transfer of four electrons, and four one-electron
reversible or quasi-reversible reductions, with anodic to cathodic
peak separations (DEp) changed from 0.050 to 0.160 V within the
scan rates from 0.010 to 0.500 Vsꢁ1. The peak currents increased
linearly with the square root of scan rates, indicating the purely
diffusion-controlled behavior [46]. The difference in the voltam-
metric behaviour of 4 as compared with that of 3 is due to the fact
that metallo phthalocyanines, such as MnPc, CoPc and FePc, having
a metal that possesses energy levels lying between the HOMO and
the LUMO of the Pc ligand, in general exhibit redox processes
centered on the metal [42, 47e50]. For CoPc complexes, the first
oxidation and first reduction processes occur on the metal center in
polar solvent such as DMF and DMSO; however the first oxidation
process occurs on the Pc ring in nonpolar solvent such as DCM and
THF. Therefore, the first reduction and the first oxidation processes
of 4 could be assigned easily to the [Co(II)Pc(ꢁ2)]/[Co(I)Pc(ꢁ2)]ꢁ
and [Co(II)Pc(ꢁ2)]/[Co(III)Pc(ꢁ2)]þ redox couples and the other
reduction processes to the Pc ring. The separation between the first
oxidation and the first reduction potentials of the metal center for 4
(0.65 V) is comparable with the relevant values in the literature
[1,6e9], and does not reflect the HOMO-LUMO gap.
Fig. 4. (A) Emission spectra of 3 and 5 in DMF, excitation wavelengths: 640 nm for 3,
650 nm for 6, (B) Excitation spectra of 3 and 5 in DMF.
implying strongly that the second oxidation couple (O2) of 3 and
the first oxidation couple of 3 correspond to the oxidation of
ferrocene substituents simultaneously at one potential. Voltam-
metric data and the assignment of the redox couples recorded for
the complexes are listed in Table 1. The ferrocene substituents of
both 3 and 4 are oxidized at the same potential, 0.51 V vs. SCE,
probably due to the fact that the metal centers in 3 and 4 does not
influence the electron density on ferrocene substituents
considerably.
Complex 3 gives three one-electron reduction processes labelled
as R1 at ꢁ0.78 V, R2 at ꢁ1.12 V and R3 at ꢁ1.40 V, and a four-electron
oxidation process labelled as O1 at 0.51 V vs. SCE at 0.050 Vsꢁ1 scan
rate (Fig. 5 and Table 1). All the one-electron reduction processes of
3 are Pc ring based since zinc(II) metal center behaves as redox-
inactive in Pcs [42e45]. Reduction of the Pc ligand is associated to
the position of LUMO whereas its oxidation is associated to the
position of the HOMO. Thus, the difference between the potentials
of the first oxidation and the first reduction processes (DE1/2)
reflects the homoelumo gap for metal free Pcs and it is closely
related with the HOMO-LUMO gap in MPc species involving redox-
inactive metal center. DE1/2 values within the range of 1.50e1.70 V
were reported in the literature [42]. Thus, the first oxidation couple
of 3 (O1) is due to the oxidation of ferrocene substituents and Pc
ring-based first oxidation couple of 3 is probably out of the solvent-
limited potential range, and cannot be observed. The peak currents
ratios at different scan rates for all redox couples of 3 are usually
close to unity, suggesting the absence of coupled chemical reac-
tions. Anodic to cathodic peak separations (
D
Ep) changed from
Ep
0.050 to 0.180 V within the scan rates from 0.010 to 0.500 Vsꢁ1
(
D
changed from 0.060 to 0.140 V for ferrocene), indicating the
occurrence of quasi-reversible electron transfer reactions. The peak
currents increased linearly with the square root of scan rates,
indicating the purely diffusion-controlled behavior [46].
The redox potentials of 4, especially its first reduction and first
oxidation potentials are highly different as compared with those of
3 (Figs. 5 and 6, and Table 1). Within the electrochemical window of
Fig. 5. (A)Cyclicand(B)differentialpulsevoltammogramsof5.0ꢂ10ꢁ4 M3inTBAP/DMSO.

M. Çamur et al. / Journal of Organometallic Chemistry 696 (2011) 1868e1873
1873
References
[1] C.C. Leznoff, A.B.P. Lever (Eds.), Phthalocyanines: Properties and Applications,
vols. 1e4, Weinheim: VCH, New York, 1989, 1993, 1996.
[2] N.B. McKeown, Phthalocyanines Materials, Synthesis, Structure and Function.
Cambridge University Press, Cambridge, 1998.
[3] G. Torre, P. Vazquez, F. Agullo-Lopez, T. Torres, J. Mater. Chem. 8 (1998)
1671e1683.
[4] M. Nicolau, B. Cabezon, T. Torres, J. Org. Chem. 66 (2001) 89e93.
[5] H. Akkus¸ , A. Gül, Transit. Met. Chem. 26 (2001) 689e694.
[6] K.W. Poon, W. Liu, P.K. Chan, Q. Yang, T.W.D. Chan, T.C.W. Mak, D.K.P. Ng, Org.
Chem. 66 (2001) 1553e1559.
[7] K.W. Poon, Y. Yan, X. Li, D.K.P. Ng, Organometallics 18 (1999) 3528e3533.
ꢀ
[8] V. Ahsen, E. Yilmazer, M. Ertas, ÖBekaroglu, J. Chem. Soc. Dalton Trans. (1988)
401e406.
[9] C.F. van Nostrum, S.J. Picken, A.J. Schouten, R.J.M. Nolte, J. Am. Chem. Soc. 117
(1995) 9957e9965.
[10] N. Kobayashi, T. Ohya, M. Sato, S. Nakajima, Inorg. Chem. 32 (1993) 1803e1808.
[11] M.J. Cook, G. Cooke, A. Jafari-Fini, J. Chem. Soc. Chem. Commun. (1995)
1715e1716.
[12] M. Kimura, T. Hamakawa, T. Muto, K. Hanabusa, H. Shira, N. Kobayashi,
Tetrahedron Lett. 39 (1998) 8471e8474.
[13] J.A. Delaire, J. Delouis, J. Zakrzewski, Formation and quenching of the photo-
4ꢁ
excited triplet state of tetrasulfonated zinc phthalocyanine, ZnPcS4
by
azaferrocene and ferrocene, J. Photochem. Photobiol. A 141 (2001) 169e173.
[14] Z. Jin, K. Nolan, C.R. McArthur, A.B.P. Lever, C.C. Leznoff, J. Organomet. Chem.
468 (1994) 205e212.
[15] A. Togni, T. Hayashi, Ferrocenes. VCH, New York, 1995.
[16] I.R. Whittall, A.M. McDonagh, M.G. Humphrey, M. Samoc, Adv. Organomet.
Chem. 42 (1998) 291e362.
[17] D. Astruc, Electron Transfer and Radical Processes in Transition-Metal
Chemistry. VCH, New York, 1995.
[18] S.M. Sethna, N.M. Shah, Chem. Rev. 36 (1) (1945) 1e62.
[19] S.C. Haydon, Spectrosc. Lett. 8 (1975) 815e892.
[20] N. Kitamura, S. Kohtani, R. Nakagaki, J. Photochem. Photobiol. C 6 (2005)
168e185.
[21] G. Matlocsy, M. Nadasy, V. Andriska, Pesticide Chemistry, Studies in Envi-
ronmental Science. Elsevier, Budapest, 1998, pp. 32.
[22] M. Frenette, C. Coenjarts, J.C. Scaiano, Macromol. Rapid Commun. 25 (2004)
1628e1631.
[23] B. YanWang, X.Y. Liu, Y.L. Hu, Z.X. Su, Polym. Int. 58 (2009) 703e709.
[24] C.R. Moylan, J. Phys. Chem. 98 (1994) 13513e13516.
[25] Y. Tian, E. Akiyama, Y. Nagase, A. Kanazawa, O. Tsutsumi, T. Ikeda, Macromol.
Chem. Phys. 201 (2000) 1640e1652.
[26] J. Kwon Oh, V. Stöeva, J. Rademacher, R. Farwaha, M.A. Winnik, J. Polym. Sci. A
42 (2004) 3479e3489.
[27] E. Bardez, P. Boutin, B. Valeur, Chem. Phys. Lett. 191 (1992) 142e148.
[28] J. Seixas de Melo, A.L. Maçanita, Chem. Phys. Lett. 204 (1993) 556e562.
[29] J. Seixas de Melo, R.S. Becker, A.L. Macanita, J. Phys. Chem. 98 (1994)
6054e6058.
[30] K. Setsukinai, Y. Urano, K. Kikuchi, T. Higuchi, T. Nagano, J. Chem. Soc. Perkin
Trans. 2 (2000) 2453e2457.
Fig. 6. (A) Cyclic and (B) differential pulse voltammograms of 5.0 ꢂ 10ꢁ4 M 4 in TBAP/
DMSO.
[31] J. Seixas de Melo, P.F. Fernandes, J. Mol. Struct. 565e566 (2001) 69e78.
[32] H. Çakıcı, A.A. Esenpınar, M. Bulut, Polyhedron 27 (2008) 3625e3630.
[33] M. Çamur, M. Bulut, M. Kandaz, O. Güney, Polyhedron 28 (2009) 233e238.
[34] M. Çamur, M. Bulut,M. Kandaz, O.Güney, Supramol. Chem. 21(7)(2009)624e631.
[35] J.G. Young, W. Onyebuagu, J. Org. Chem. 55 (1990) 2155e2159.
[36] M. Çamur, M. Bulut, Dyes Pigm. 77 (2008) 165e170.
[37] A.A. Esenpınar, M. Bulut, Dyes Pigm. 76 (2008) 249e255.
[38] N. Kobayashi, H. Ogata, N. Nonaka, E.A. Lukyanets, Chem. Eur. J. 9 (2003)
5123e5124.
[39] A.R. Jagtap, V.S. Satam, R.N. Rajule, V.R. Kanetkar, Dyes Pigm. 82 (2009) 84e89.
[40] R. Giasson, E.J. Lee, X. Zhao, M.S. Wrighton, J. Phys. Chem. 97 (1993)
2596e2601.
[41] N.B. Thornton, H. Wojtowicz, T. Netzel, D.W. Dixon, J. Phys. Chem. B. 102
(1998) 2101e2110.
Table 1
The electrochemical data of the Pc complexes (3 and 4).
Complex Redox processes E1/2 (V vs. SCE)a
D
Ep (V)b Ipa/Ipc
D
E1/2 (V)d
c
3
4
O1
R1
R2
R3
O2
O1
R1
R2
R3
R4
0.51
ꢁ0.78
ꢁ1.12
ꢁ1.40
ꢁ0.37
0.48
ꢁ0.43
ꢁ0.82
ꢁ1.11
ꢁ1.40
0.080
0.080
0.060
0.080
0.100
0.090
0.060
0.120
0.060
0.080
1.00
0.97
0.98
0.98
1.05
0.98
1.05
0.97
1.00
1.02
1.29
0.91
[42] A.B.P. Lever, E.R. Milaeva, G. Speier, in: C.C. Leznoff, A.B.P. Lever (Eds.),
Phthalocyanines: Properties and Applications, vol. 3, VCH Publishers, New
York, 1993, pp. 1e63.
a
b
c
E1/2¼(Epa þ Epc)/2 at 0.050 Vsꢁ1
.
[43] T. Ceyhan, A. Altındal, A.R. Özkaya,
Ö Çelikbıçak, B. Salih, M.K. Erbil,
ꢀ
Ö Bekaroglu, Polyhedron 26 (2007) 4239e4249.
[44] Z. Odabas¸ , A. Altındal, A.R. Özkaya, M. Bulut, B. Salih, Ö Bekaroglu, Polyhedron
26 (2007) 3505e3512.
ΔEp ¼ Epa e Epc at 0.050 Vsꢁ1
.
ꢀ
Ipa/Ipc for reduction, Ipc/Ipa for oxidation processes at 0.050 Vsꢁ1
.
d
DE1/2 ¼ E1/2(first oxidation) e E1/2(first reduction). These values do not reflect
ꢀ
[45] D. Kulaç, M. Bulut, A. Altındal, A.R. Özkaya, B. Salih, ÖBekaroglu, Polyhedron
the HOMO-LUMO gap for 3 and 4.
26 (2007) 5432e5440.
[46] A.J. Bard, L.R. Faulkner, Electrochemical Methods: Fundamentals and Appli-
cations, second ed.. Wiley, New York, 2001.
ꢀ
[47] M. Özer, A. Altındal, A.R. Özkaya, M. Bulut, Ö Bekaroglu, Polyhedron 25 (2006)
Acknowledgement
3593e3602.
ꢀ
[48] A.R. Özkaya, E. Hamuryudan, Z.A. Bayır, Ö Bekaroglu, J. Porphyrins Phthalo-
cyanines 7 (2000) 689e697.
[49] M. Kandaz, A.R. Özkaya, Ö Bekaroglu, Monats. Chem. 132 (2001) 1013e1022.
[50] A. Koca, A.R. Özkaya, M. Selçukoglu, E. Hamuryudan, Electrochim. Acta 52
We are thankful to the Reseach Foundation of Marmara
University, Commission of Scientific Research Project (BAPKO)
[FEN-A-090909-0302].
ꢀ
ꢀ
(2007) 2683e2690.