Synthesis, characterization, and electrochemical and electrical properties of novel mononuclear and binuclear ball-type Zn(II) and Co(II) phthalocyanines substituted with 1a,8b-dihydronaphtho[b]naphthofuro-[3,2-d]furan-7,10-diyl

Article abstract of DOI:10.1016/j.poly.2007.03.047

New mononuclear phthalocyanines [Zn(II) 4 and Co(II) 6] and ball-type bisphthalocyanines [Zn(II) 5 and Co(II) 7] have been synthesized from the corresponding compound 3, which can be obtained from the reaction of 4-nitrophthalonitrile 1 with 1a,8b-dihydronaphtho[b]naphthofuro[3,2-d]furan-7,10-diol 2. The novel compounds have been characterized by elemental analysis, UV/Vis, IR, ¹H NMR and MASS spectroscopy. The electrochemical measurements show the formation of various mixed-valence oxidized and reduced species, due to intramolecular interactions between the two phthalocyanine units in the ball-type binuclear metallophthalocyanines. Detailed studies of the effect of temperature on the electronic properties of the films were investigated by dc conductivity and impedance spectroscopy techniques at temperatures between 290 K and 460 K. Thermally activated conductivity dependence on temperature was observed from the dc measurements. The ac results give a power law behavior in which the frequency exponent decreases with temperature. It was observed that the impedance spectra consist of a curved line at low temperature. These curved lines transform into a full semicircle with increasing temperature.

Full text of DOI:10.1016/j.poly.2007.03.047

Polyhedron 26 (2007) 3505–3512
www.elsevier.com/locate/poly
Synthesis, characterization, and electrochemical and electrical
properties of novel mononuclear and binuclear ball-type Zn(II)
and Co(II) phthalocyanines substituted with
1a,8b-dihydronaphtho[b]naphthofuro-[3,2-d]furan-7,10-diyl
a
b
a
a
¨
Zafer Odabaßs , Ahmet Altındal , Ali Rıza Ozkaya , Mustafa Bulut ,
c
d,
*
¨
Bekir Salih , Ozer Bekarog˘lu
a
Department of Chemistry, Marmara University, Faculty of Science and Letters, 34722, Go¨ztepe, Istanbul, Turkey
Department of Physics, Marmara University, Faculty of Science and Letters, 34722, Go¨ztepe, Istanbul, Turkey
b
c
Department of Chemistry, Hacettepe University, 06532 Ankara, Turkey
d
_
Department of Chemistry, Technical University of Istanbul, Maslak-Istanbul, Turkey
_
Received 14 February 2007; accepted 24 March 2007
Available online 10 April 2007
Abstract
New mononuclear phthalocyanines [Zn(II) 4 and Co(II) 6] and ball-type bisphthalocyanines [Zn(II) 5 and Co(II) 7] have been syn-
thesized from the corresponding compound 3, which can be obtained from the reaction of 4-nitrophthalonitrile 1 with 1a,8b-dihydro-
1
naphtho[b]naphthofuro[3,2-d]furan-7,10-diol 2. The novel compounds have been characterized by elemental analysis, UV/Vis, IR, H
NMR and MASS spectroscopy. The electrochemical measurements show the formation of various mixed-valence oxidized and reduced
species, due to intramolecular interactions between the two phthalocyanine units in the ball-type binuclear metallophthalocyanines.
Detailed studies of the effect of temperature on the electronic properties of the films were investigated by dc conductivity and impedance
spectroscopy techniques at temperatures between 290 K and 460 K. Thermally activated conductivity dependence on temperature was
observed from the dc measurements. The ac results give a power law behavior in which the frequency exponent decreases with temper-
ature. It was observed that the impedance spectra consist of a curved line at low temperature. These curved lines transform into a full
semicircle with increasing temperature.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Ball-type; Mononuclear; Bisphthalocyanine; Synthesis; Electrochemistry, Electrical conductivity
1. Introduction
actinoid sandwich dimmers [1–3], covalently linked cofacial
dimmers [4–6], planar homo- and hetero-dimers sharing a
common aromatic ring or linked by other units [7–11]
and linear dimers linked by flexible alkyl chains [12,13]
have been synthesized. These dimers and multimers, espe-
cially those with rigid cofacial configurations, usually show
spectroscopic electrochemical and electrical properties
which differ significantly from the parent monomers. A
strong interaction between the halves of the molecule is
usually detected in electronic absorption and MCD spec-
troscopy and electrochemistry. The redox couples observed
in monomeric species are usually split into two couples. It
Binuclear phthalocyanines (Pcs) have attracted great
attention because of their unique spectroscopic, electro-
chemical and electrical properties. In this respect, binuclear
Pcs linked by various kinds of bridges, i.e., lanthanoid and
*
Corresponding author. Address: Bilim Sokak, Kardesler Apt., No. 6/9,
Erenko¨y, Istanbul, Turkey. Tel.: +90 216 359 01 30; fax: +90 216 386 08
24.
¨
E-mail address: obekaroglu@gmail.com (O. Bekarog˘lu).
0277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.03.047

3506
Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
was suggested that electron cloud overlap is important for
a strong interaction.
For a long time, binuclear Pcs have been obtained by the
tetramerization of phthalonitrile (or its derivatives) with
basic catalysts in a suitable solvent such as pentanol,
hexanol, dimethylformamide or o-dichlorobenzene at
180–200 ꢁC. Recently investigators have used new reaction
techniques such as microwawe irradiation or heating of the
solid phase to obtain binuclear Pcs. In this paper, in our
continuing efforts, we have used the ‘‘heating of the solid
phase’’ method for the synthesis of novel ball-type four
1a,8b-dihydronaphtho[b]naphthofuro-[3,2-d]furan-7,10-diol
bridged zinc(II) and cobalt(II) phthalocyanines (Scheme 1).
The first synthesis of ball-type binuclear Pcs was
reported in 2003 by the Zefirov group [14]. However, the
studies on this type of Pc did not continue until we recently
reported the synthesis, characterization and electrical,
electrochemical and gas sensing properties of ball-type
t-butylcalix-[4]arene bridged [15] and 1,10-methylene-di-
naphthalen-2-ol bridged [16] metal free and/or metallopht-
halocyanines. These novel compounds showed interesting
mixed-valence behavior.
CN
CN
CN
NC
O
OH HO
O
O2N
CN
CN
i
+
O
O
O
O
3
2
1
ii (a,b)
NC
O
NC
NC
CN
O
O
O
O
O
O
N
O
O
N
N
N
M
N
N
N
N
O
O
O
O
O
O
O
CN
CN
NC
NC
4
6
M: Zn Co
+
N
O
O
N
N
N
N
O
O
O
M
N
N
N
N
N
O
O
O
O
O
N
N
N
N
N
O
O
O
M
N
O
O
O
5
7
M: Zn Co
Scheme 1. (i) K2CO3, DMSO; (ii) a: Zn(CH3COO)2 Æ 2H2O, 300 ꢁC; b: Co(CH3COO)2 Æ 4H2O, 280 ꢁC.

Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
3507
The electrical and electrochemical properties of the com-
pounds are also presented.
5 min under dry N2 atmosphere at 300 ꢁC. After cooling
to room temperature, 5 mL of DMF was added to the
residue to dissolve the product. The reaction mixture was
precipitated by adding water. The precipitate was filtered,
multiply washed at first with hot water and then with hot
ethanol in order to eliminate the unreacted starting materi-
als, and dried in vacuo. Then, the crude product was washed
with acetic acid, methanol, ethanol, acetonitrile and acetone
for 12 h, respectively, in a soxhlet apparatus. The residue
was coarsely fractionated on a silica gel column eluting with
chloroform and a gradient of chloroform–THF up to 100%
THF. This compound is soluble in chloroform (slightly),
THF, DMF and DMSO. Mp > 350 ꢁC. Yield of 4: 6 mg
(5%). Yield of 5: 30 mg (15%).
2. Experimental
The starting materials 1 and 2 were synthesized by the
methods described previously in the literature [17–20]. IR
spectra were recorded on a Shimadzu FTIR-8300 spectro-
photometer as KBr pellets. Electronic spectra were
recorded on a Shimadzu UV-1601 spectrophotometer.
Elemental analyses were performed by the Instrumental
Analysis Laboratory of Tubitak–Ankara. 1H NMR spectra
were recorded in d-chloroform, d-dimethylsulfoxide and
d-acetone with a Mercury-Vx 400 MHz instrument. Mass
spectra were acquired on a Voyager-DEꢂ PRO MALDI-
TOF mass spectrometer (Applied Biosystems, USA)
equipped with a nitrogen UV-Laser operating at 337 nm.
Spectra were recorded either in reflectron and linear modes
with an average of 50 shots.
Compound 4 is slightly soluble in DCM and CHCl3, and
soluble in THF, DMF and DMSO. Mp > 350 ꢁC. IR (KBr
pellet) mmax/cmꢀ1: 835, 945, 1041, 1085, 1184, 1220, 1249,
1332, 1394, 1446, 1487, 1514, 1606, 1722, 2231, 2850,
2925, 3066. Anal. Calc. for C152H72N16O16Zn: C, 74.71;
1
H, 2.97; N, 9.17. Found: C, 74.02; H, 3.02; N, 9.21%. H
2.1. Synthesis
NMR (DMSO-d6) d, ppm: 8.25–7.60 (m, 32H, arom.),
7.50–6.85 (m, 32H, arom.), 7.32 (m, 4H, O–CH–O), 5.80
(m, 4H, Ar–CH–Ar). MS (MALDI-TOF): m/z 2446
(M+H).
2.1.1. 4,40-(1a,8b-Dihydronaphtho[b]naphthofuro[3,2-d]-
furan-7,10-diyl)bis(oxy)diphthalonitrile (3)
A mixture of 4-nitro-1,2-dicyanobenzene 1 (0.657 g,
Compound 5 is soluble in THF, DMF and DMSO.
Mp > 350 ꢁC. IR (KBr pellet) mmax/cmꢀ1: 834, 946, 1042,
1094, 1179, 1223, 1257, 1361, 1394, 1454, 1476, 1517,
1606, 1654, 2850, 2925, 3025. Anal. Calc. for
3.8 · 10ꢀ3 mol) and 4,40-(1a,8b-dihydronaphtho[b]napht-
hofuro[3,2-d]furan-7,10-diyl)bis(oxy)diphthalonitrile
2
(0.650 g, 1.9 · 10ꢀ3 mol) in 20 mL dry dimethylsulfoxide
(DMSO) was stirred at room temperature under N2.
K2CO3 (0.828 g, 6 · 10ꢀ3 mol) was added into the mixture
over a period of 2 h. After stirring the reaction mixture for
a further 24 h, the undissolved salt was removed by filtra-
tion. The reaction mixture was poured into water
(100 mL) and stirred. The precipitate was filtered and
washed with water. The residue was chromatographed by
silica gel and eluted with CH2Cl2 (DCM). Yield: 1.14 g
(96%). This compound is soluble in CHCl3, DCM, tetrahy-
drofuran (THF), dimethylformamide (DMF), acetone and
acetonitrile. Mp: 152 ꢁC. IR (KBr pellet) mmax/cmꢀ1: 833,
968, 1056, 1134, 1184, 1249, 1280, 1307, 1361, 1419,
1454, 1485, 1519, 1593, 1631, 2229, 3082. Anal. Calc. for
C38H18N4O4: C, 76.76; H, 3.05; N, 9.42. Found: C, 76.33;
C
152H72N16O16Zn2: C, 72.76; H, 2.89; N, 8.93. Found: C,
1
72.53; H, 3.08; N, 9.23%. H NMR (DMSO-d6) d, ppm:
8.18–6.80 (m, 64H, arom.), 6.85 (m, 4H, O–CH–O), 5.70
(m, 4H, Ar–CH–Ar). MS (MALDI-TOF): m/z 2510
(M+H).
2.1.3. [2,10,16,24-Tetrakis(1a-hydronaphtho-
[b]naphthofuro[3,2-d]-7,10-dyl-4-oxyphthalo-nitrile)-
phthalocynaninatocobalt(II)] (6) and [1ıa,8ıbtetrakis-
bis{(2ı,10ı,16I,24ı)-phthalocyaninatocobalt(II)}-
dioxynaphtho-[b]-naphthofuro[3,2-d]furan-7,10-diyl] (7)
A mixture of compound 3 (0.200 g, 0.337 mmol) and
Co(OAc)2 Æ 4H2O (0.130 g, 0.522 mmol) was powdered in
a quartz crucible and heated in a sealed glass tube for
5 min under dry N2 atmosphere at 280 ꢁC. After cooling
to room temperature, the blue-green reaction product
was obtained, isolated and purified with using the same
procedure explained above for 4 and 5. Yield of 6: 5 mg
(4.5%). Yield of 7: 28 mg (14%).
Compound 6 is slightly soluble in DCM and CHCl3,
and is soluble in THF, DMF and DMSO. Mp >
350 ꢁC. IR (KBr pellet) mmax/cmꢀ1: 752, 956, 1053,
1090, 1179, 1228, 1253, 1361, 1453, 1476, 1517, 1610,
1628, 2231, 2850, 2925, 3059. Anal. Calc. for
1
H, 2.95; N, 9.83%. H NMR (chloroform-d) d, ppm: 5.4
(d, J = 5.85 Hz 1H), 7.01 (d, J = 8.58 Hz, 2H), 7.01 (d,
J = 8.19 Hz, 2H), 7.15 (s, 2H), 7.27 (d, J = 5.85 Hz, 1H),
7.29 (d, J = 8.58 Hz, 2H), 7.60 (d, J = 8.19 Hz, 2H), 7.65
(br ds, 2H), 7.84 (d, J = 8.97 Hz, 2H), 7.95 (d, J =
8.97 Hz, 2H).
2.1.2. [2,10,16,24-Tetrakis(1a-hydronaphtho[b]-
naphthofuro[3,2-d]-7,10-dyl-4-oxyphthalo-nitrile)-
phthalocynaninatozinc(II)] (4) and [1ıa,8ıb-tetrakis-bis-
{(2ı,10ı,16I,24ı)-phthalocyaninatozinc(II)}dioxynaphtho-
[b]-naphthofuro[3,2-d]furan-7,10-diyl] (5)
A mixture of compound 3 (0.2 g, 0.3 · 10ꢀ3 mol) and
Zn(OAc)2 Æ 2H2O (0.100 g, 2.4 · 10ꢀ3 mol) was powdered
in a quartz crucible and heated in a sealed glass tube for
C152H72N16O16Co: C, 74.91; H, 2.98; N, 9.20. Found:
C, 74.77; H, 2.87; N, 9.15%. MS (MALDI-TOF): m/z
2438 (M+H).
Compound 7 is soluble in chloroform (slightly), THF,
DMF and DMSO. Mp > 350 ꢁC. IR (KBr pellet) mmax
/

3508
Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
cmꢀ1: 833, 956, 1056, 1094, 1118, 1181, 1226, 1253, 1363,
1407, 1452, 1473, 1518, 1609, 1655, 2850, 2925, 3059. Anal.
Calc. for C152H72Co2N16O16: C, 73.14; H, 2.91; N, 8.98.
Found: C, 73.05; H, 2.88; N, 8.73%. MS (MALDI-TOF):
m/z 2496 (M+H).
20–96 h) [17]. Our key starting material is compound 3
which can be obtained via the reaction of compound 1
and 2, in dry DMSO in the presence of dry K2CO3. 4, 5
and 6, 7 were synthesized by heating 3 with Zn(OAc)2 Æ
2H2O and Co(OAc)2 Æ 4H2O, respectively, in a sealed tube
under a N2 atmosphere (Scheme 1).
1
2.2. Electrochemical measurements
Elemental analysis, IR, H NMR, MASS and UV/Vis
spectra confirm the proposed structures of the compounds.
Compounds 3, 4 and 6 show a sharp intense CN vibration
band at 2229–2231 cmꢀ1 in the IR spectra. The spectra of
compounds 3–7 showed Ar–O–Ar peaks at 1220–
1285 cmꢀ1, C@C (in the phenyl and naphthalene rings)
peaks at 1560–1655 cmꢀ1, C@N peaks at 1670–1720
cmꢀ1, aromatic CH peaks at 3060–3070 cmꢀ1 and aliphatic
The cyclic voltammetry (CV) and controlled potential
coulometry (CPC) measurements were carried out with a
Princeton Applied Research Model VersaStat II potentio-
stat/galvanostat controlled by an external PC and utilizing
a three-electrode configuration at 25 ꢁC. The working elec-
trode was a Pt plate with a surface area of 0.10 cm2. The
surface of the working electrode was polished with a 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. A saturated calomel electrode
(SCE) was employed as the reference electrode and sepa-
rated from the bulk of the solution by a double bridge.
The ferrocene/ferrocenium couple (Fc/Fc+) was also used
as an internal standard. Electrochemical grade tetrabutyl-
ammonium perchlorate (TBAP) in extra pure DMSO and
DCM was employed as the supporting electrolyte at a con-
centration of 0.10 mol dmꢀ3. 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 measure-
ments. For controlled (CPC) studies, a Pt gauze working
electrode (10.5 cm2 surface area), Pt wire counter electrode,
separated by a glass bridge, and a SCE as the reference
electrode were used.
1
CH peaks at 2840–2945 cmꢀ1. The H NMR spectra were
also in good correlation with the structure of the synthe-
1
sized compounds. In the H NMR spectrum of compound
3, which was taken in chloroform-d, the phenyl protons
appeared at 7.65 (br s), 7.60 (d) and 7.13 (br d) ppm,
naphthalene protons at 7.95 (d), 7.84 (d), 7.29 (d), 7.15
(s) and 7.01 (br d) ppm, and CH protons at 7.27 (d) and
1
5.40 (d) ppm. In addition, in the H NMR spectra of 4
and 5, which were taken in DMSO-d6, the aromatic
protons appeared in the range 8.25–6.80 (m) ppm and the
aliphatic CH peaks 5.70–5.80 (m) ppm.
The UV–Vis spectra of 4–7 in DMF showed character-
istic absorptions between 610 and 710 nm in the Q-band
region. The Q-band observed for the compounds was
attributed to the p ! p* transition from the highest
occupied molecular orbital (HOMO) to the lowest unoccu-
pied molecular orbital (LUMO) of the Pc ring. The other
bands (B) in the UV region at 300–350 nm were observed
due to transitions from the deeper p levels to the LUMO
(Table 1).
2.3. Electrical conductivity and impedance measurements
For the electrical characterization, an interdigital comb
structure with 100 lm gap on a glass substrate was used.
Thin films of the compounds were obtained by the spin-
coating method. The substrate temperature was kept con-
stant at 290 K during deposition of the materials over the
electrodes. Dc conductivity and impedance spectra mea-
surements were performed between 290 and 460 K using
a Keithley 617 electrometer. Ac conductivity and imped-
ance measurements were carried out with a Keithley 3330
LCZ meter in the frequency range 40 Hz to 105 Hz, in
the temperature range from 290 to 460 K. Both dc and
ac conductivity measurements were performed under
10ꢀ3 mbar in the dark. The conductivity data were
recorded using an IEEE 488 data acquisition system incor-
porating a personal computer.
An a-cyano-4-hydroxycinnamic acid (ACCA) (10 mg/
mL in acetonitrile–water mixture, 1:1 v/v) matrix for 6
and 2,5-dihydroxy benzoic acid (DHB) (20 mg/mL acetoni-
trile) MALDI matrices were prepared. MALDI samples
were prepared by mixing the complex (2 mg/mL in tetrahy-
drofuran for 6 and 7, and in dichloromethane for 4 and 5)
with the matrix solution (1:20 v/v) in a 0.5 mL eppendorfꢃ
micro tube. Finally 1 lL of this mixture was deposited on
Table 1
UV–Vis data for 4–7 in DMF
Compound
k, nm (loge, Mꢀ1 cmꢀ1
)
4
704 (4.169),
618a (3.786)
673 (4.178),
339 (4.218)
647 (3.930)
5
6
684 (3.358),
339 (3.390)
620 (2.818)
3. Results and discussion
672 (4.258),
332a (4.208)
611a (3.734),
304 (4.264)
3.1. Synthesis
The synthesis of the bisphthalodinitriles is based on the
reaction of diols with an excess of compound 1 (DMF or
DMSO in the presence of dry K2CO3 as a base, at 25 ꢁC,
7
705 (3.799),
620a (3.801)
674 (3.843),
339 (4.248)
646 (3.901)
a
= Shoulder.

Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
3509
the sample plate, dried at room temperature and then
analyzed.
2
1
(A)
4
2
R3
R2
R1
0
O1
3.2. Electrochemistry
(B)
-1
R3
1.0 0.5 0.0 -0.5 -1.0 -1.5
E / V versusSCE
The redox properties of the complexes were examined by
cyclic voltammetry, differential pulse voltammetry and
controlled potential coulometry in DMSO/TBAP. A sum-
mary of the relevant electrochemical data is given in Table
2. Typical voltammograms for the mononuclear metall-
ophthalocyanines [Zn(II)Pc(ꢀ2) 4, Co(II)Pc(ꢀ2) 6] and
ball-type dinuclear phthalocyanines {[Zn(II)Pc(ꢀ2)]2 5,
[Co(II)Pc(ꢀ2)]2 7} are shown in Figs. 1 and 2. The CPC
studies showed that all the redox processes for the com-
plexes involve the transfer of one electron.
R1-2
0
8
(D)
(C)
6
-2
-4
4
2
R3
R1
R2
R3
R1-2
0
O
-2
0.0
-0.5
-1.0
E /V vs. SCE
-1.5
1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0
E / V versusSCE
0.0
-0.5
-1.0
-1.5
E / V versus SCE
Fig. 1. Voltammograms of 4 and 5 in DMSO/TBAP. A: CV of 4 at
0.100 V sꢀ1. B: CV of 5 at 0.100 V sꢀ1. C: CV of 5 at 0.010 V sꢀ1. D: DPV
Complex 4 displayed three quasi-reversible reduction
waves at E1/2 = ꢀ0.69, E1/2 = ꢀ1.00 and E1/2 = ꢀ1.35 V
vs. SCE, with considerably high anodic to cathodic peak
separations, and a nearly reversible oxidation peak with a
relatively low peak separation, Fig. 1A. These phthalocya-
nine ring-based redox processes were examined as a func-
tion of potential scan rate in order to determine the
mode of mass transport. The peak currents for the pro-
cesses R1, R2, R3 and O1 increased in direct proportion
to the square root of the scan rate between 0.025 and
0.500 V/s, thus suggesting that the relevant reactions are
controlled by diffusion.These redox processes are probably
ligand based since zinc is not redox active in phthalocya-
nine complexes. The redox potentials measured for 4 are
consistent with the general redox characteristics reported
previously for similar Pcs [21].
of 5 at 0.100 V sꢀ1
.
weak interactions between the two cofacial phthalocyanine
rings in 5, and thus a rounded-shaped voltammogram is
observed. The redox processes of this complex are better
defined in the voltammogram recorded at 0.010 V sꢀ1
,
Fig. 1C. Unfortunately, the oxidation process/processes
are still ill-defined. However, the differential pulse voltam-
mogram of the complex enabled us to detect the splitting of
the first reduction process clearly, Fig. 1D. The observed
redox potentials suggest that the mixed-valence splitting
energy for the Pc(ꢀ2)/Pc(ꢀ3) process in 5 (0.22 V) is lower
as compared with that reported recently (0.43 V) for
ball-type four 1,10-methylenedinaphthalen-2-ol bridged
metallophthalocyanine, [Zn(II)Pc(ꢀ2)]2 [16]. This provides
additional support for relatively weak interactions between
the phthalocyanine rings in 5, and is consistent with the
The voltammogram for 5 at 0.100 V sꢀ1 is shown in
Fig. 1B. It appears that characteristic Pc(ꢀ2)/Pc(ꢀ3) redox
process of monophthalocyanines is not well-split due to
Table 2
The electrochemical data for 1–4 in DMSOa
Complex
Redox processes
E1/2 (V)
DEp (V)
DE (V)
DEs (V)
4
[Zn(II)Pc(ꢀ1)]+/Zn(II)Pc(ꢀ2)
Zn(II)Pc(ꢀ2)/[Zn(II)Pc(ꢀ3)]ꢀ
[Zn(II)Pc(ꢀ3)]ꢀ/[Zn(II)Pc(ꢀ4)]2ꢀ
[Zn(II)Pc(ꢀ4)]2ꢀ/[Zn(II)Pc(ꢀ5)]3ꢀ
O1
R1
R2
R3
0.66
ꢀ0.69
ꢀ1.00
ꢀ1.35
0.06
0.26
0.40
0.14
1.35
6
5
[Co(III)Pc(ꢀ2)]+/Co(II)Pc(ꢀ2)
Co(II)Pc(ꢀ2)/[Co(I)Pc(ꢀ2)]ꢀ
[Co(I)Pc(ꢀ2)]ꢀ/[Co(I)Pc(ꢀ3)]2ꢀ
O1
R1
R2
0.43
ꢀ0.39
ꢀ1.33
0.14
0.10
0.08
0.82
[Zn(II)Pc(ꢀ2)]2/[Zn(II)Pc(ꢀ2) Æ Zn(II)Pc(ꢀ3)]ꢀ
[Zn(II)Pc(ꢀ2) Æ Zn(II)Pc(ꢀ3)]ꢀ/[Zn(II)Pc(ꢀ3)]2
[Zn(II)Pc(ꢀ3)]22ꢀ/[Zn(II)Pc(ꢀ3) Æ Pc(ꢀ4)]3ꢀ
R1
R2
R3
ꢀ0.69b
ꢀ0.91b
ꢀ1.46b
0.18b
0.10b
0.12b
0.22b
0.39
2ꢀ
7
[Co(II)Pc(ꢀ2) Æ Co(III)Pc(ꢀ2)]+/[Co(II)Pc(ꢀ2)]2
O1
R1
R2
R3
0.50
ꢀ0.36
ꢀ0.75
ꢀ1.34
0.08
0.20
0.34
0.08
0.86
[Co(II)Pc(ꢀ2)]2/[Co(II)Pc(ꢀ2) Æ Co(I)Pc(ꢀ2)]ꢀ
[Co(II)Pc(ꢀ2) Æ Co(I)Pc(ꢀ2)]ꢀ/[Co(I)Pc(ꢀ2)]2
2ꢀ
[Co(I)Pc(ꢀ2)]22ꢀ/[Co(I)Pc(ꢀ2) Æ Co(I)Pc(ꢀ3)]3ꢀ
Half-wave potentials in DMSO versus the Fc/Fc+ couple correspond approximately with the above 4–7 data minus 0.50 V. E1/2 values were measured
by cyclic voltammetry [E1/2 = (Epa + Epc)/2. The peak separation values (DEp = Epa ꢀ Epc) are reported at 0.100 V sꢀ1. DE is the potential difference
between the first oxidation and first reduction potentials. It represents the HOMO–LUMO gap for 4 and 5, but the charge transfer transition for 6 and 7
involving redox-active metal centers. DEs indicates the mixed-valence splitting energy for the relevant split redox couple.
a
b
Measured by differential pulse voltammetry.

3510
Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
2ꢀ
step and doubly oxidized [Co(I)Pc(ꢀ2)]2 species in the
second step. The splitting observed for the Co(II)/Co(I)
process in this study may be attributed to the interactions
between the two cobalt centers, which are probably held
in close proximity by the cofacial ligand geometry, result-
ing in overlap of their dz2 orbitals along the cobalt–cobalt
axis. The third reduction and the first oxidation couples
can be assigned to the formation of [Co(I)Pc(ꢀ2) Æ
3
2
6
4
(A)
1
R2
0
R1
O1
-1
-2
-3
(B)
R3
1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0
2
E / V vs. SCE
R2
0
R1
Co(I)Pc(ꢀ3)]3ꢀ
and
[Co(II)Pc(ꢀ2) Æ Co(III)Pc(ꢀ2)]+
O1
respectively, since all redox couples involve the transfer
of one electron. The formation of a fully reduced ligand
and a fully oxidized metal species could not be observed.
These processes appear to be out of the available solvent/
electrolyte limited potential range. The splitting of metal
or phthalocyanine based redox processes as a result of
the interaction between the cofacial phthalocyanine units
has also been reported recently for ball-type four 1,10-
methylenedinaphthalen-2-ol bridged [Co(II)Pc(ꢀ2)]2 [16].
The observed redox potentials suggest that the mixed-
valence splitting energy, DEs, for the Co(II)/Co(I) process
in 7 (0.39 V) is smaller as compared with that reported
recently for ball-type four 1,10-methylenedinaphthalen-2-
ol bridged [Co(II)Pc(ꢀ2)]2 (0.44 V). This implies relatively
weak interactions between the phthalocyanine rings in 7,
and is consistent with the difference between the bridges
in 7 and the recently reported [Co(II)Pc(ꢀ2)]2. It may be
concluded that the distance between the cofacial phthalo-
cyanine rings or metal centers in 7 is higher than that in
[Co(II)Pc(ꢀ2)]2. Moreover, it appears that Co(II)/Co(I)
mixed-valence species in 7 are more stable than the
Pc(ꢀ2)/Pc(ꢀ3) mixed-valence species in 5.
-2
1.0
0.5
0.0
-0.5
-1.0
-1.5
E / V versus SCE
Fig. 2. Cyclic voltammograms of 6 (A) and 7 (B) at 0.100 V sꢀ1 in
DMSO/TBAP.
difference in the bridges in 5 and the recently reported
[Zn(II)Pc(ꢀ2)]2. It is expected that the distance between
the cofacial phthalocyanine rings is higher in 5 than that
in [Zn(II)Pc(ꢀ2)]2.
Voltammetric behavior of 6 is different from that of 4, in
terms of redox potentials. It indicates two well-defined
one-electron reduction processes at E1/2 = ꢀ0.39 and E1/2
=
ꢀ0.67 V versus SCE, and a one-electron oxidation process
at E1/2 = 0.43 V versus SCE, Fig. 2A. Some metallopht-
halocyanines vary in their electrochemical behavior accord-
ing to their environment, i.e., the oxidation of
Co(II)Pc(ꢀ2) can lead to [Co(III)Pc(ꢀ2)]+ or [Co(II)-
Pc(ꢀ1)]+ depending on whether there are any available
suitable coordinating species that would stabilize the
Co(II) center [21]. Such electrochemistry, especially of
Co(II)Pc(ꢀ2) and Fe(II)Pc(ꢀ2) is split into two sections,
that referring to donor solvents and that referring to
non-donor solvents. The main difference lies in whether
the metal or the ring is oxidized first. Donor solvents
strongly favor Co(III)Pc(ꢀ2) by coordinating along the
axis to form six coordinate species. If such donor solvents
are absent, then oxidation to Co(III) is inhibited and ring
oxidation occurs first. Thus, the first oxidation and the first
reduction processes of 6 are probably metal based and
correspond to Co(II)Pc(ꢀ2)/[Co(III)Pc(ꢀ2)]+ and Co(II)-
Pc(ꢀ2)/[Co(I)Pc(ꢀ2)]ꢀ, respectively,while the second
reduction is ring based, since the voltammetric measure-
ments were carried out in DMSO/TBAP.
3.3. Electrical conductivity and impedance spectroscopy
The temperature dependent dc behavior of the films was
determined from the slope of the current–voltage (I–V)
measurements by using the following relation:
I
d
rdc
¼
V ð2n ꢀ 1Þl ꢁ h
where I is the measured current, V is the bias voltage, d is
the electrode spacing, n is the number of electrode finger
pairs, l is the overlap length of the electrode fingers and h
is the thickness of the electrodes. A linear I–V behavior
was found in the voltage range of ꢀ1 V to 1 V, indicating
no rectifying properties. Well defined straight lines were
obtained from Arrhenius plots (logarithms of dc conduc-
tivity versus inverse temperature). This linear temperature
dependence of the dc conductivity suggest the presence of
only one conduction mechanism, assuming that the domi-
nant levels are the conduction and valence bands in the
whole temperature range for the films of 4–7. The observed
electrical conductivity values at room temperature for 4–7
are 2.7 · 10ꢀ12, 5.1 · 10ꢀ12, 4.2 · 10ꢀ12 and 1.6 · 10ꢀ12
S/cm, respectively. The order of dc conductivities observed
for these compounds are 5 > 6 > 4 > 7 for all temperatures
investigated. The value of the activation energy was derived
The ball-type 7 displays three one-electron quasi-revers-
ible reduction couples and a reversible one-electron oxida-
tion couple within the potential limits of the DMSO/TBAP
medium, Fig. 2B. A comparison of the first two reduction
potentials of 7 with those of 6 clearly suggests the forma-
tion of mixed valence species. The difference between the
first and second reduction potentials of 7 is 0.39 V, whilst
it is 0.92 V for 6. The two one-electron reduction couples
can be attributed to the stepwise reduction of the two
Co(II) centers in 7, and thus to the formation of mixed
valence [Co(II)Pc(ꢀ2) Æ Co(I)Pc(ꢀ2)]ꢀ species in the first

Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
3511
from the slope of the logrdc vs. 1/T graph, and is 0.67 eV
2.5E+06
2.0E+06
1.5E+06
1.0E+06
5.0E+05
3.0E+02
2 kHz.
for 4, 0.75 eV for 5, 0.83 eV for 6 and 0.55 eV for 7.
The ac conductivity and impedance spectrum measure-
ments were performed in the temperature range
290–460 K and for frequencies between 40 and 105 Hz.
Fig. 3 shows the frequency dependence of the measured
ac conductivity at 373 K for films of 4–7. The figure indi-
cates the strong conductivity dependence on frequency at
around room temperature, with weaker frequency depen-
dence at high temperatures for the films. It can be seen
from Fig. 3 that the ac conductivity increases with fre-
quency. The frequency dependence of the conductivity
can be represented by the universal power law for all
compounds
10 kHz.
100 kHz.
280
330
380
430
480
Temperature (K)
rac ¼ Axs
ð1Þ
Fig. 4. Temperature dependence of the real part of the impedance for
compound 5.
where x is the angular frequency, A and the frequency
exponent, s, are material dependent constants. This type
of frequency dependent ac conduction has been explained
on the basis of two distinct mechanisms for carrier conduc-
tion. One of them is the Quantum Mechanical Tunelling
model (QMT). According to this model, the conduction oc-
curs by means of thermally assisted Quantum Mechanical
Tunelling. The other model, which is also known as the
Correlated Barrier Hopping (CBH) model, is based on
the concept of charged defects and in this method bipola-
rons hop between two charged defect states D+ and Dꢀ
over the barrier separating them, rather than tunneling
through the barrier. In these two models, the frequency
exponent s is found to have two different trends with tem-
perature and frequency [22]. Our calculations showed that s
is definitely a function of temperature for all compounds
and shows a general tendency to increase with decreasing
temperature. This is in agreement with the prediction of
the CBH model. The decrease in s with temperature is in
contradiction with the QMT model.
ature dependence of the real part of the impedance,
Z(x) = R(x) + iX(x), at indicated frequencies for compound
5. The observed R(T) reveals that there is an obviously dif-
ferent tendency for different ranges of temperature.
Namely, over the temperature range from 290 K to the crit-
ical temperature there appears a positive temperature coef-
ficient (PTC), and a negative temperature coefficient (NTC)
is seen above this temperature. The crossover occurs
between 375 and 411 K. It is clear from Fig. 4 that in the
transition region from PTC to NTC, there is a peak of
R(T). At a frequency of 2 kHz, it is clearly found that a
peak of R(T) displays at about 411 K, which is considered
as a switching point from PTC to NTC. This peak weakens
slowly and shifts to the low temperature region with
increasing frequency. On the other hand, it was found from
the analysis of the temperature dependence of the imagi-
nary part of the impedance that X(T) displays a negative
temperature coefficient for all frequencies. Similar results
of the impedance spectra were obtained for all tempera-
tures investigated. The measured impedance curves are
composed of a not fulfilled quasi-vertical line at low
To ensure complete electrical properties of the com-
pounds, the impedance spectroscopy technique was used
in the frequency range 40–105 Hz. Fig. 4 shows the temper-
1.0E-06
4
5
6
7.0E+06
6.0E+06
5.0E+06
4
7
1.0E-07
1.0E-08
1.0E-09
5
6
7
4.0E+06
3.0E+06
2.0E+06
1.0E+06
0.0E+00
1
10
100
1000
10000
100000 1000000
frequency (Hz.)
0.0E+00
5.0E+06
1.0E+07
R (ohm)
1.5E+07
2.0E+07
Fig. 3. Frequency dependence of the ac conductivity at 373 K for the films
of 4–7.
Fig. 5. Impedance spectra of the compounds at 400 K.

3512
Z. Odabaßs et al. / Polyhedron 26 (2007) 3505–3512
[5] N. Kobayashi, Y. Yanagisawa, T. Osa, H. Lam, C.C. Leznoff, Anal.
Chem. 6 (1990) 813.
[6] N. Kobayashi, H. Lam, W.A. Nevin, P. Janda, C.C. Leznoff, A.B.P.
Lever, Inorg. Chem. 29 (1990) 3415.
[7] N. Kobayashi, H. Lam, W.A. Nevin, P. Janda, C.C. Leznoff, T.
Koyama, A. Monden, H. Shirai, J. Am. Chem. Soc. 116 (1994)
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[8] N. Kobayashi, M. Numao, R. Kondo, S. Nakajima, T. Osa, Inorg.
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[9] N. Kobayashi, J. Chem. Soc., Chem. Commun. (1991) 1203.
[10] N. Kobayashi, Y. Higashi, T. Osa, Chem. Lett. (1994) 1813.
[11] E.M. Garcia-Frutos, F. Fernandez-Lazaro, E.M. Maya, P. Vazquez,
T. Torres, J. Org. Chem. 65 (2000) 6841.
temperatures, suggesting pure capacitive behavior. On the
complex plane plot at high temperatures, only a depressed
semicircle with different radii were observed, Fig. 5, for
compounds 4–7 at higher temperatures, indicating devia-
tion from the Debye dispersion relation. In the case of a
depressed semicircle in the impedance spectra, the relaxa-
tion time is considered as a distribution of values, rather
than a single relaxation time.
Acknowledgements
[12] S. Vigh, H. Lam, P. Janda, A.B.P. Lever, C.C. Leznoff, R.L. Cerny,
Can. J. Chem. 69 (1991) 1457.
[13] (a) E.M. Maya, P. Vazquez, T. Torres, Chem. Eur. J. 5 (1999)
2004;
This work was supported partly by the Turkish Acad-
emy of Sciences (TUBA), The State Planning Organization
(Project Number: 2003 K 120810) and The Research Fund
of Marmara University.
(b) K. H Schweikart, M. Hanack, Eur. J. Org. Chem. (2000)
2551;
(c) E.M. Maya, P. Vazquez, T. Torres, L. Gobbi, F. Diedrich, S.
Pyo, L. Echegoyen, J. Org. Chem. 65 (2000) 823.
[14] A.Y. Tolbin, A.V. Ivanov, L.G. Tomilova, N.S. Zefirov, J. Porphyrins
Phthalocyanines 7 (2003) 162.
Appendix A. Supplementary material
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.poly.2007.
03.047.
¨
¨
[15] T. Ceyhan, A. Altındal, A.R. Ozkaya, M.K. Erbil, B. Salih, O.
Bekarog˘lu, Chem. Commun. (2006) 320.
¨
[16] Z. Odabaßs, A. Altındal, B. Salih, M. Bulut, O. Bekarog˘lu,
Polyhedron 26 (2007) 695.
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