Tetrakis-phthalocyanines bearing electron-withdrawing fluoro functionality: Synthesis, spectroscopy, and electrochemistry

Article abstract of DOI:10.1002/hc.20545

In this study, 2,9,16,23-tetrakis-4'-(2,3,5,6-tetrafluoro)-phenoxy- phthalocyaninatometalfree and metal(II) complexes, (H₂PcBzF ₁₆, ZnPcOBzF ₁₆, CuPcOBzF ₁₆, and CoPcOBzF ₁₆) (Bz: Benzene) (2H, Zn, Cu

Full text of DOI:10.1002/hc.20545

Heteroatom Chemistry
Volume 20, Number 5, 2009
Tetrakis-Phthalocyanines Bearing
Electron-Withdrawing Fluoro Functionality:
Synthesis, Spectroscopy, and Electrochemistry
1
1
2
¨
Ahmet T. Bilgic¸li, Mehmet Kandaz, Ali Rıza Ozkaya,
and Bekir Salih3
1Department of Chemistry, Sakarya University, 54140 Esentepe, Sakarya, Turkey
2Department of Chemistry, Marmara University, 34722 Go¨ztepe, Istanbul, Turkey
3Department of Chemistry, Faculty of Science, Hacettepe University, 06532 Beytepe Campus,
Ankara, Turkey
Received 23 December 2008; revised 12 April 2009
give ligand-based reduction and oxidation processes,
ABSTRACT: In this study, 2,9,16,23-tetrakis-4ꢀ-
CoPcOBzF16 gives both ligand and metal-based redox
(2,3,5,6-tetrafluoro)-phenoxy-phthalocyaninato-
processes, in harmony with the common metal-
metalfree and metal(II) complexes, (H2PcBzF16,
lophthalocyanine complexes. Redox processes due
ZnPcOBzF16, CuPcOBzF16, and CoPcOBzF16) (Bz:
to both aggregated and disaggregated species were
Benzene) (2H, Zn, Cu, and Co), have been pre-
simultaneously observed during the first reduction
pared directly from the corresponding 4ꢀ-(2,3,5,6-
process. The nature of the metal-based redox processes
fluorophenylthio)-phthalonitrile compounds in the
was confirmed using spectroelectrochemical measure-
presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
ꢁ
C
ments. 2009 Wiley Periodicals, Inc. Heteroatom Chem
in high boiling quinoline solvent. Tetrafluoro atoms
20:262–271, 2009; Published online in Wiley InterScience
on 2,3,5,6-position of benzene at the peripheral sites
(www.interscience.wiley.com). DOI 10.1002/hc.20545
of phthalocyanines (Pcs) give rise interesting solu-
bility to tetrakismetallophthalocyanines. Although
all complexes were soluble in DCM, CHCl3, THF,
INTRODUCTION
DMF, and DMSO with increasing order, complexes
synthesized, particularly H2PcBzF16, CuPcOBzF16,
have very limited solubility in DMF and DMSO.
The complexes have been characterized by elemental
Phthalocyanines have varied chemistry resulting
from their rich π-electron system, and thus are
known as excellent modifiable functional materi-
als [1–3]. Accordingly, there are literally hundred
of publications and patents related to their various
technological fields [4–6]. Because of their very high
tinctorial nature, diverse redox chemistry, and high
thermal and chemical stability, various applications
such as semiconductivity [7], electrochromic dis-
plays [8], chemical sensors [9], and optical proper-
ties [10,11] have prompted the researchers to synthe-
size various types of metallophthalocyanines (MPcs)
recently [3–8,12–14]. Introducing electron donor
1
analysis, FTIR, H NMR, UV–vis, and MALDI–TOF
mass spectral data. The cyclic voltammetry and dif-
ferential pulsed voltammetry of the complexes show
that while H2PcBzF16, CuPcOBzF16, and ZnPcOBzF16
Correspondence to: Mehmet Kandaz; e-mail: mkandaz@sakarya.
edu.tr.
Contract grant sponsor: Research Fund of Sakarya University.
Contract grant sponsor: TBAG.
Contract grant number: 108T094.
2009 Wiley Periodicals, Inc.
c
ꢀ
262

Tetrakis-Phthalocyanines Bearing Electron-Withdrawing Fluoro Functionality 263
and acceptor groups into the phthalocyanine (Pc)
base at 170–185◦C. Metal-free Pc 2 was obtained in
N,N-dimethylamino ethanol under N2 atmosphere,
also in the presence of DBU as a strong base
(Scheme 1). The blue cyclotetramerization products
2–5 were purified by column chromatography in
moderate yield (40% for 2, 44% for 3, 32% for 4,
and 37% for 5). Elemental analysis results and the
spectral data (1H NMR, FTIR, and MALDI–TOF
MS) of all the new products are consisted with
the assigned formulations. The phthalocyanine
products (M = 2H, Zn, Cu, and Co) were isolated
as a mixture of isomers as expected. The presence
of isomers could be verified with slight broadening
encountered in the UV–vis absorption bands and
ring strongly affects its spectral, electrical, and elec-
trochemical properties. Tetra- and octa-substituted
MPcs have higher chemical stability as compared
to unsubstituted ones. Electron-withdrawing sub-
stituents at the periphery of the macrocycle cause
a large increase in the ionization potential of the
system, protect the MPc from oxidative destruction
[15–17], and thus enhance its catalytic activity. From
the viewpoint of organic semiconductors, it is known
that substitution of electron donor and acceptor
groups leads to p-type and n-type characteristics of
the Pc ring, respectively [7,18–20].
The main problem limiting applications of ph-
thalocyanines (Pcs) in many fields is still their lim-
ited solubility. Their solubility can be increased,
however, by introducing electron-withdrawing ( F,
Cl, Br) and electron-donating ( NH2, Ar S ,
RO , RS ) bulky or long chain alkyl groups into the
peripheral sites [21–25]. The formation of constitu-
tional isomers and the higher dipole moment of the
tetrasubstituted Pcs resulting from the unsymmetri-
cal arrangement of the substituents on the periph-
ery leads to higher solubility of Pcs in many organic
solvents [26].
Redox processes of Pcs can be shifted
by electron-withdrawing and/or electron-repelling
groups [22]. Thus, fluorinated MPcs are currently
receiving a great deal of attention due to electron-
withdrawing nature of fluorine atoms [17,27]. Al-
though many studies on the chemistry of MPcs in so-
lution, which have been limited to Pc with electron-
donating substituents, have been carried out, those
with electron-attracting groups, especially contain-
ing fluorine atoms, have not been extensively studied
[17,22,27,28].
1
broadening in the H NMR when compared with
those of octa-substituted Pcs composed of a single
isomer [13,15, 26a]. All the analytical and spectral
data are consistent with the predicted structures.
The 16 peripheral fluoro atoms confer on these
molecules moderate solubility in halogenated sol-
vents and good solubility in THF, DMF, DMSO,
and DMAA, in comparison with unsubstituted
Pcs.
The FTIR spectra of Pcs involved strong C F
stretching band on the periphery with small shifts
in comparison with that of 1. In the meantime, CN
band at 2226 cm−1 in the spectrum of 1 disappeared
after Pc formation. Aliphatic C H and aromatic
C H peaks at above and below 3000 cm−1 and the
rest of the spectra were closely similar to those of
compound 1, and diagnosed easily.
The 1H NMR spectra of 2 and 3 were almost iden-
tical with starting compound 1 except small shifts
and core NH signal in 2. The NH protons in the in-
ner core of the 2 were also very well characterized by
1
the H NMR spectroscopy, which showed a peak at
Here, we report the synthesis and char-
−1.52 ppm as a result of the 18 π-electron system of
the Pc ring [22]. The aromatic protons in the lower
field region and 12 different aromatic carbon atoms
between 110 and 160 ppm in the 1H NMR spectrum
are the most distinctive signals for the characteriza-
tion of 1. The rather broad bands in the case of 2 and
3 were probably due to both chemical exchange as-
sociated with aggregation–disaggregation equilibria
that occur at high concentrations used in the NMR
measurements and the fact that the products ob-
tained in these reactions are the mixture of four posi-
tional isomers, which are expected to show chemical
shifts only slightly differing from each other [1,26a].
UV–vis spectra of the Pc complexes exhibit char-
acteristic Q and B bands in DMSO. Two principle
π–π∗ transitions are seen for Pcs: a lower energy
Q band (∼650–750 nm, π–π∗ transition from the
highest occupied molecular orbital (HOMO) to the
lowest unoccupied molecular orbital (LUMO) of
acterization of
a
new ligand, 4ꢀ-(2,3,5,6-
fluorophenylthio)-phthalonitrile, obtained through
2,3,5,6-fluorolthiophenol and 4-nitrophthalonitrile
in the presence of K2CO3 in dimethylformamide
(DMF) and its complexes. We also investigate their
redox properties by cyclic and differential pulse
voltammetry and spectroelectrochemistry.
RESULTS AND DISCUSSION
Synthesis and Characterization
Fluoro functional MPcs 3–5 were prepared
by the templated cyclization from 4ꢀ-(2,3,5,6-
tetrafluorophenylthio)-phthalonitrile,
1,
and
anhydrous metal salts, Zn(OAc)2, CuCl2, and
CoCl2 in quinoline in the presence of 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) as a strong
Heteroatom Chemistry DOI 10.1002/hc

264 Bilgic¸li et al.
SCHEME 1 Synthetic route of 4ꢀ-(2,3,5,6-Tetrafluorophenylthio)phthalonitrile (1) and its free and metal complexes (M = 2H,
Zn(II), Cu(II), Co(II). (i) 2,3,5,6-Tetrafluorothiophenol and 4-nitrophthalonitrile and K2CO3 in DMF at 40◦C for 24 h. (ii) anhydrous
Zn (acac)2, CuCl2, and CoCl2, DBU , quinoline.
the complexes) and a higher energy B band {∼300–
350 nm, deeper π–π∗ transition from the highest oc-
cupied MOs (a1u and a2u) to the LUMO (eg)} [2]. The
Q-band absorptions in the UV–vis absorption spec-
tra of all MPcs were observed as a single band of
high intensity due to a single π–π∗ transition with
shoulders at slightly higher energy side of the Q band
(681 nm for 3, 678 nm for 4, and 672 nm for 5) as
seen in Fig. 1. The small differences between the ab-
sorption bands of synthesized compounds are due
to the ionic radius of the metal centers. The metal-
free Pc 2 showed splitting of Q band as expected
(Qx = 671 nm and Qy = 703 nm) with a shoulder
at the higher energy side of the Q band. The ef-
fect of S-substitution on the periphery for all Pcs
when compared with those of O-substituted deriva-
tives was the shift of Q bands to longer wavelengths
[3,8,13–15,21–27]. On the other hand, the Q band
position of the Pcs bearing electron-withdrawing flu-
oro functional groups shifted to shorter wavelengths,
compared with nonfluorinated thio- or phenoxy-
substituted compounds, as expected [17,27].
MALDI–TOF Mass Spectra
Positive ion and reflectron mode MALDI–TOF mass
spectrum of 2 was carried out using α-cyano-4-
hydroxycinnamic acid MALDI matrix (Fig. 2). Pro-
tonated molecular ion peak was observed at 1234.20
Da with the other isotopic peaks mainly resulting
FIGURE 1 UV–visible spectra of 2–5 in DMSO.
Heteroatom Chemistry DOI 10.1002/hc

Tetrakis-Phthalocyanines Bearing Electron-Withdrawing Fluoro Functionality 265
Dithranol was a suitable matrix for these types of
metal complexes to get clearer MALDI–TOF mass
spectrum, and also it could be concluded that metal
complexes of these ligands were more stable in
dithranol matrix. Positive ion and reflectron mode
MALDI–TOF mass spectrum of 5 was obtained as
high-resolution spectrum without any fragmenta-
tion in dithranol matrix. Experimental isotopic peak
distributions of protonated molecular ion peak of
this complex overlapped exactly with its theoretical
calculated isotopic peak distributions. This informa-
tion gives the full characterization of this complex by
MALDI–TOF mass spectroscopy [26a,26b]. The re-
sults showed that the complexes were characterized
precisely by MALDI–TOF mass spectroscopy.
FIGURE
2 Positive ion and reflectron mode MALDI–
TOF mass spectrum of 2 was obtained in α-cyano-4-
hydroxycinnamic acid MALDI matrix using N2 laser accu-
mulating 50 laser shots. Inset spectrum shows expanded
molecular mass region of the complex.
Electrochemical Measurements
Cyclic and differential pulse voltammetry of 2–5
were carried out on a platinum working electrode
in DMSO. Controlled-potential coulometry studies
showed that the redox processes monitored for these
compounds generally involve the transfer of one
electron. Voltammetric data of the compounds are
presented in Table 1.
from the isotopic distribution of carbon, which over-
laps with the mass of 2 calculated theoretically from
its elemental composition.
Figure 3 shows the MALDI–TOF mass spectra
of 3. For 3 and 4, all high-resolution MALDI–TOF
mass spectra were obtained most efficiently using
only dithranol MALDI matrix compared to the other
novel MALDI matrices. Mainly protonated molec-
ular ion peaks and the dithranol peak at around
227 Da were characterized for 3 and 4. It was con-
cluded that all experimental isotopic peak distribu-
tions of protonated molecular ions overlapped com-
pletely with their theoretical calculated isotopic peak
distributions. All MALDI–TOF results showed that
Compound 2 displayed three reduction waves at
E1/2 = −0.54 V, E1/2 = −0.81 V, and E1/2 = −1.57 V
versus saturated calomel electrode (SCE), with char-
acteristic anodic to cathodic peak separations for
one-electron transfer processes (Fig. 4A). These Pc
ring-based redox processes were examined as a func-
tion of potential scan rate to determine the mode of
mass transport. The anodic-to-cathodic peak current
ratio for the first reduction couple (II) is higher than
unity. In addition, this ratio increases noticeably
with increasing scan rate while the cathodic peak be-
comes sharp. These observations suggest that com-
pound 2 is adsorbed on the electrode surface. When
the electrode is left in solution for a long time be-
fore the first scan, the effect of adsorption on the
peak current ratio was more pronounced. On the
other hand, in the case that the voltammetric cycle
was continued at a constant scan rate, the anodic-to-
cathodic peak current ratio for couple II decreased
with the scan number, suggesting that the adsorbed
species are lost from the surface during the first re-
duction process. The cathodic peak currents of the
couples II–IV increased in direct proportion to the
square root of the scan rate between 0.025 and 0.500
V s−1, thus suggesting that the relevant reactions are
controlled by diffusion. The first oxidation process
of metal-free Pcs could not be detected usually in
the studies reported previously [29–31]. Differential
pulse voltammetry enabled us to identify the first ox-
idation process of 2 at 0.96 V versus SCE without the
FIGURE 3 Positive ion and reflectron mode MALDI–TOF
mass spectrum of 3 was obtained in dithranol (1,8-dihydroxy-
10H-anthracen-9-one) MALDI matrix using nitrogen laser ac-
cumulating 50 laser shots. Inset spectrum shows expanded
molecular mass region of the complex.
Heteroatom Chemistry DOI 10.1002/hc

266 Bilgic¸li et al.
TABLE 1 Voltammetric Data for 2, 3, 4, and 5
Compound
Redox Couple
E1/2 (V)a versus SCE and Fc/Fc+b
ꢀEp (V)c
2
Pc(–1)/Pc(–2) (I)
Pc(–2)/Pc(–3) (II)
Pc(–3)/Pc(–4) (III)
Pc(–4)/Pc(–5) (IV)
Pc(–1)/Pc(–2) (I)
Pc(–2)/Pc(–3) (II)
Pc(–3)/Pc(–4) (III)
Pc(–4)/Pc(–5) (IV)
Pc(–1)/Pc(–2) (I)
Pc(–2)/Pc(–3) (II)
Pc(–3)/Pc(–4) (III)
Pc(–4)/Pc(–5) (IV)
Co(III)/Co(II) (I)
0.96 (0.46)d
−0.54 (−1.04)
−0.81 (−1.31)
−1.57 (−2.07)
0.67 (0.17)
−0.78 (−1.28)
−1.19 (−1.69)
−1.46 (−1.96)
0.61 (0.11)
−0.75 (−1.25)
−0.94 (−1.44)
−1.63 (−2.13)
0.49 (−0.01)
−0.41 (−0.91)
−1.15 (−1.65)
−1.62 (−2.12)
–
0.080
0.060
0.060
0.080
0.060
0.060
0.060
0.070
0.100
0.080
0.140
0.100
0.060
0.060
0.200
3
4
5
Co(II)/Co(I) (II)
Pc(–2)/Pc(–3) (III)
Pc(–3)/Pc(–4) (IV)
aE1/2 = (Epa + Epc)/2 at 0.050 V s−1
.
bThe values in parenthesis indicate the potentials versus Fc/Fc+.
cꢀEp = Epa − Epc at 0.050 V s−1
.
dThis value is the anodic peak potential, which could be identified only by differential pulse voltammetry.
corresponding cathodic peak (peak I in Fig. 4B). The
difference between the first oxidation and the first
reduction process is 1.50 V. This difference corre-
sponds to the gap between the HOMO and the LUMO
and is consistent with the previously reported values
for metal-free Pcs [29,32].
working electrode was scanned toward negative po-
tentials starting at 0 V versus SCE, compound 4
displayed four reduction peaks whereas three cor-
responding reoxidation peaks were observed dur-
ing the reverse scan. The first two reduction pro-
cesses for MPcs are separated by about 0.30–0.40 V
[1]. However, the difference between the first two
reduction peaks (IIꢀ and II) was about 0.10–0.20 V,
depending on the scan rate. The current ratio of
Figure 5 indicates cyclic and differential pulse
voltammograms of 4. When the potential of the
FIGURE 4 Cyclic (A) and differential pulse (B) voltammo-
grams of 2 in DMSO–TBAP solution.
FIGURE 5 Cyclic (A) and differential pulse (B) voltammo-
grams of 4 in DMSO–TBAP solution.
Heteroatom Chemistry DOI 10.1002/hc

Tetrakis-Phthalocyanines Bearing Electron-Withdrawing Fluoro Functionality 267
these peaks (IIꢀc/IIc) was observed to increase with
increasing scan rate, and became finally a compos-
ite wave at high scan rates. Surprisingly, there was
no any potential difference between the peaks IIa
and IIꢀc at 0.050 while peak IIꢀc appeared unusually
at less negative potentials with respect to peak IIa
at the scan rates lower than 0.050 V s−1. These ob-
servations also imply the adsorption of compound 3
on the electrode surface. Another possible and addi-
tional effect associated with the first two reduction
processes is the presence of equilibrium between the
aggregated and disaggregated species since couple II
is split at low scan rates. It is possible that peaks IIcꢀ
and IIc correspond to the reduction of aggregated
and disaggregated species, respectively. In the case
that aggregation–disaggregation equilibrium is slow
relative to the electrochemical time scale, reduction
processes due to both species could simultaneously
be monitored. Moreover, the current ratio of peak IIcꢀ
to peak IIc decreased with dilution (Fig. 6). This pro-
vided additional support for the presence of aggre-
gated and disaggregated species. The similarities be-
tween the redox behavior of 2 and 4, in general, both
indicating three one-electron reduction couples and
a one-electron oxidation process (Table 1), show that
redox processes of 4 are also ligand based, and Cu(II)
metal center is not redox active. The redox processes
of 4 occur at the potentials more negative than those
of 2. This can be attributed to the difference in the
polarizing power of the central metal and hydrogens
[29]. As compared with 4, similar redox behavior
was observed with compound 3 with some differ-
ences in redox potentials, which can be attributed to
the differences in polarizing power of different metal
centers (Table 1). The redox potentials measured for
2–4 are consistent with the general redox character-
istics reported previously for similar Pcs, being less
FIGURE 7 Cyclic (A) and differential pulse (B) voltammo-
grams of 5 in DMSO–TBAP solution.
negative as compared with those given for unsubsti-
tuted Pcs in the literature [29]. This positive potential
shift can be attributed to the electron-withdrawing
effect of fluorine atoms in the complexes. Therefore,
it was possible to observe the third reduction pro-
cess for these complexes, which cannot be moni-
tored generally.
Typical cyclic and differential pulse voltammo-
grams for 5 are shown in Fig. 7. Although it also
indicates three one-electron reduction processes at
E1/2 = −0.41 V, E1/2 = −1.15 V, and E1/2 = −1.62 V
versus SCE, and a one-electron oxidation process
at E1/2 = 0.49 V versus SCE (Table 1), the redox
potentials of 5 are different from those of other
compounds. If the transition metal ion at the cen-
ter has no accessible d orbital levels lying between
the HOMO and LUMO gap of a Pc species, then its
redox chemistry will appear very much like that of
a main group Pc species. The nickel, copper, zinc,
and some other MPcs behave in this fashion, with
the M(II) central ion being unchanged as the MPc
unit is either oxidized or reduced. On the other
hand, MPcs, such as MnPc, CoPc, and FePc, hav-
ing a metal that possesses energy levels lying be-
tween the HOMO and the LUMO of the Pc ligand,
in general exhibit redox processes centered on the
metal [29,30,33–36]. In addition, these species vary
FIGURE 6 Cyclic voltammograms of 4 at two different con-
centrations at 0.100 V s−1 in DMSO–TBAP solution.
Heteroatom Chemistry DOI 10.1002/hc

268 Bilgic¸li et al.
their electrochemical behavior according to their en-
vironment, i.e., the oxidation of Co(II)Pc(–2) can
lead to [Co(III)Pc(–2)]+ or [Co(II)Pc(–1)]+ depend-
ing on whether there are any available suitable coor-
dinating species that would stabilize the Co(II) cen-
ter. Such electrochemistry, especially of Co(II)Pc(–2)
and Fe(II)Pc(–2), is split into two sections that re-
ferring to donor solvents and nondonor solvents.
The main difference lies in whether 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 oxida-
tion and the first reduction processes of 5 are prob-
ably metal based and correspond to Co(II)Pc(–2)/
[Co(III)Pc(–2)]+ and Co(II)Pc(–2)/[Co(I)Pc(–2)]−, re-
spectively, while the second and third reductions are
ring based, since the voltammetric measurements
were carried out in DMSO–TBAP. It was observed
that the shape of the couple II (Fig. 7A), correspond-
ing the first reduction process of 5, is strongly af-
fected by the scan rate. This is probably due to
the aggregation–disaggregation equilibrium. It ap-
pears that at high scan rates at which aggregation–
disaggregation equilibrium is slow with respect to
the time scale of electrochemical measurement, the
first reduction process is split into two waves (IIꢀ and
II), corresponding to the reduction of aggregated and
disaggregated species. This behavior was well char-
acterized by rounded shape of couple II in cyclic and
differential pulse voltammograms (Fig. 7). However,
adsorption on the electrode surface is not observed
for 5.
To provide additional support for the identifica-
tion of the metal-based redox processes of 5, spec-
troelectrochemistry of this complex was also stud-
ied. Typical absorption spectra for the original 5 and
its electrochemically generated species are shown in
Fig. 8. Figure 8A shows the UV–vis spectral changes
of 5 during its first reduction at −0.60 V versus
SCE. The Q band absorption at 672 nm shifts to
713 nm, while new band at 485 nm appears with a
shoulder around 441 nm. The spectral changes have
well-defined isosbestic points at 293, 399, 564, and
697 nm. The new band at 485 nm and shifting of
the Q band indicate the formation of [Co(I)Pc(−2)]−
species, confirming that first reduction of 5 occurs
at the metal center [37]. Upon the second reduction
at −1.30 V versus SCE, the Q band absorption at
713 nm and the shoulder at 441 nm decrease with-
out shift (Fig. 8B). In the meantime, the absorption
at 485 nm increases slightly in intensity with the
redshift to 490 nm while the absorption between
500 and 600 nm increases. Clear isosbestic points
FIGURE 8 In situ UV–vis spectral changes during (A) the
first reduction, (B) the second reduction, and (C) the first
oxidation processes of 5.
were observed at 355, 406, 640, and 784 nm. These
spectral changes at the potential of the couple III
are characteristic for a ring-based reduction in com-
plex 5, confirming our voltammetric assignment of
this process to [Co(I)Pc(−2)]−/[Co(I)Pc(−3)]2− [38].
Figure 8C shows the spectral changes during oxida-
tion of 5. The original Q band absorption at 672 nm
increases with a clear shift to 687 nm. In the mean-
time, the absorption at the red side of the shoulder
at around 616 nm decreases. These spectral changes,
especially the shift in the Q band absorption, are typ-
ical of Co(II)Pc(–2)/[Co(III)Pc(–2)]+ redox process
Heteroatom Chemistry DOI 10.1002/hc

Tetrakis-Phthalocyanines Bearing Electron-Withdrawing Fluoro Functionality 269
[38] and result in the isosbestic points at 303, 361,
485, and 672 nm, together with those in the B band
region.
electrode configuration at 25◦C. The working elec-
trode was a platinum 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 par-
ticle size of 50 nm. A platinum wire served as the
counterelectrode. Saturated calomel electrode was
employed as the reference electrode and separated
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
tetrabutylammonium perchlorate (TBAP) in extra
pure dimethylsulfoxide (DMSO) was employed as
the supporting electrolyte at a concentration of 0.10
mol dm−3. High purity N2 was used for deoxy-
genating 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), platinum wire
counterelectrode, separated by a glass bridge, and
SCE as a reference electrode were used. The spec-
troelectrochemical measurements were carried out
on an Agilent model 8453 diode array spectropho-
tometer equipped with the potentiostat/galvanostat
and utilizing a three-electrode configuration of thin
layer quartz spectroelectrochemical cell at 25◦C. The
working electrode was transparent platinum gauze.
Platinum wire counterelectrode separated by a glass
bridge and a SCE reference electrode separated from
the bulk of the solution by a double bridge were
used.
EXPERIMENTAL
2,3,5,6-Fluorolthiophenol, 4-nitrophthalonitrile di-
ethyl ether, tetrahydrofuran (THF), tetrabutylam-
monium tetrafluoroborate, MX2(M = Zn , Cu, and
Co; X = O2CMe and Cl) and 4-nitrophthalonitrile
were purchased from Merck (Darmstadt, Germany)
and Alfa Aesar (Karlsruhe, Germany) Chemical Co.
and were used as received. THF was distilled from
anhydrous CaCl2 and acetophenon. Chromatogra-
phy was performed with silica gel from Aldrich. All
other reagents were obtained from Merck, Aldrich,
and Alfa Aesar Chemical Co. and were used with-
out purification. All reactions were carried out un-
der dry N2 atmosphere unless other was noted, and
homogeneity of the products was tested in each
step by TLC (silica gel, chloroform (CHCl3), hex-
ane, and methanol (MeOH)). FTIR spectra (KBr)
were recorded on ATI UNICOM-Mattson 1000 spec-
trophotometer. Elemental analysis (C, H, and N) was
performed at the Instrumental Analysis Laboratory
of Marmara University. Routine UV–visible spec-
tra were obtained in a quartz cuvette on a Unicom
1
UV-2 spectrometer. H NMR and 13C NMR spectra
were recorded on a Bruker 300 spectrometer. Mul-
tiplicities are given as s (singlet), d (doublet), and t
(triplet). Mass spectra were acquired on a Voyager-
DETM PRO MALDI–TOF mass spectrometer (Applied
Biosystems, USA) equipped with a nitrogen UV–laser
operating at 337 nm, both in linear and reflectron
modes with average of 50 and 100 shots for linear
and reflectron modes.
4ꢀ-(2 3,5,6-Tetrafluorophenylthio)-
phthalonitrile 1
2,3,5,6-Tetrafluorothiophenol (1.05 g, 6.35 mmol, ex-
cess) and 4-nitrophthalonitrile (1.00 g, 5.78 mmol)
were dissolved in dry DMF (10 cm3) and heated at
40◦C in N2 atmosphere for 1 h. Then finely ground
anhydrous potassium carbonate (∼1.0 g excess) was
added portionwise to mixture over the period of 0.5 h
at 30◦C. After the reaction mixture was kept at this
temperature under N2 atmosphere for 2 days, it was
cooled to room temperature and poured in to c.a. 200
mL ice water. The creamy precipitate formed was
filtered and dissolved in CHCl3 and washed with 5%
NaHCO3 to remove starting uncreated compounds.
The creamy solution was then dried with anhydrous
Na2SO4 and filtered. It was chromatographed over
a silica gel column using a mixture of CHCl3:MeOH
(100/5) as eluent, giving blue powder 1. Finally, the
pure powder was dried in a vacuum. Yield: 1.32 g
(66%); mp = 156◦C; Anal. Calcd for C14H4F4N2S (308
g/mol): C, 54.55; H, 1.30; N, 9.09. Found: C, 54.20;
H, 1.32; N, 8.83. IR (thin film) ν: (cm−1); 3100 (w,
MALDI samples were prepared by mixing sam-
ple solutions (4 mg/mL) with the matrix solution
(1:10 v/v) in a 0.5-mL Eppendorf micro tube. Fi-
®
nally, 1 μL of this mixture was deposited on the sam-
ple plate, dried at room temperature, and then ana-
lyzed. α-Cyano-4-hydroxycinnamic acid (15 mg/mL
1:1 water–acetonitrile) MALDI matrix for 2 and
Dithranol (1,8-dihydroxy-10H-anthracen-9-one) (20
mg/mL THF) MALDI matrix for 3–5 were prepared.
MALDI samples were prepared by mixing com-
plex (2 mg/mL in acetonitrile) with the matrix so-
®
lution (1:10 v/v) in a 0.5-mL Eppendorf micro
tube. Finally, 1 μL of this mixture was deposited on
the sample plate, dried at room temperature, and
then analyzed [8,22,26a]. The cyclic voltammetry
and controlled potential coulometry (CPC) measure-
ments were carried out with a Princeton Applied Re-
search model VersoStat II potentiostat/galvanostat
controlled by an external PC and utilizing a three-
Heteroatom Chemistry DOI 10.1002/hc

270 Bilgic¸li et al.
Ar H), 3051 (w, Ar CH), 2226 (C N, st), 1627, 1604
(C C), 1577 (C N), 1492 (st), 1438, 1377 ( C F),
1272 (Ar S Ar), 1234, 1188, 1072, 914 (st) 891, 871,
heated with efficient stirring at 170–180◦C for about
8 h under N2 atmosphere. After cooling to room tem-
perature, resulting powder solid was washed several
times successively with hexane, MeOH, and filtered
to remove any inorganic and organic impurities until
the filtrate was clear. The blue product was isolated
by silica gel column chromatography with CHCl3 to
remove unreacted starting impurities and then with
THF/CHCl3 (1:2 v/v) as eluent to obtain main crude
product and then dried in vacuo. This product is sol-
uble in CHCl3, acetone, THF, DMF, DMSO, and pyri-
dine. Yield: 0.28 g (44%); mp >200◦C; Anal. Calcd
For C56H16F16N8S4Zn (1297 g/mol): C, 51.81; H, 1.23;
N, 8.64. Found: C, 51.77; H, 1.26; N, 8.54%. FTIR
(KBr) ν (cm−1): 3066 (w, broad, Ar H), 1722 (vw),
1627 (C C), 1487 (st C F), 1435 (w), 1381, 1306,
1232 (Ar S Ar), 1180, 1097, 1037, 916 (st), 889, 740
(Ar F, bending), 707. 1H NMR (DMSO-d6) δ: 8.22 (s,
H, ortho to Ar C S), 8.07 (dd, H, ortho to CN) , 8.90
(dd, H, meta to CN), 6.77 (ortho to Ar C F); UV–vis
(DMSO), λmax (nm): 681 (Q), 644 (agg), 613, 357 (B);
MS (MALDI–TOF, Ditranol as matrix) m/z : 1297.26
[M + H]+.
1
837, 709, 524. H NMR (DMSO-d6) δ: 8.30 (s, H, or-
tho to Ar C S), 8.10 (dd, H, ortho to CN) , 8.02 (dd,
H, meta to CN), 6.82 (ortho to Ar C F); 13C NMR
([D6]-DMSO) δ: 148.8 (Ar C F), 148.8 (Ar C F),
147.3 (Ar C F), 147.3 (Ar C F), 140.7 (Ar C S),
136.2 (Ar C, ortho to Ar C S), 135.1 (Ar C or-
tho to Ar C CN), 131.5 (Ar C , ortho to Ar C CN),
117.4 (Ar C ortho to CN), 116.54 (Ar CN), 116.52
(Ar CN), 114.3 (Ar C ortho to CN), 109.0 (Ar C,
ortho to Ar S), 106.4 (Ar C, ortho to Ar C F).
EI/MS m/z: 308.2 [M+].
2,9,16,23-Tetrakis-
4ꢀ-(2,3,5,6-tetrafluorophenylthio)-
phthalocyaninatometal-free 2
A mixture of 1 (0.10 g; 0.32 mmol), DBU (0.05 mL),
and dry N-N-dimethylaminoethanol was heated
with stirring to 150–160◦C for 12 h under N2 atmo-
sphere in a sealed tube. The deep green-blue product
was cooled to room temperature and a waxy solid
was washed successively with MeOH several times
to remove any inorganic and organic impurities, un-
til the filtrate was clear. Further purification was
carried out by column chromatography with silica
gel (eluent: CHCl3/MeOH; 10/1, and then THF) and
dried in vacuum. Compound 1 is less soluble than
metal-substituted ones in both halogenated and po-
lar solvent mentioned above.
2,9,16,23-Tetrakis-4ꢀ-(2,3,5,6-
tetrafluorophenylthio)-
phthalocyaninatocopper(II) 4
A mixture of compound 1 (0.10 g; 0.32 mmol), an-
hydrous CuCl2 (0.01 g; 0.08 mmol; left one night in
oven at 110◦C), and DBU (0.05 mL) in dry quinoline
was heated to 180◦C under N2 atmosphere for 8 h
(1.00 mL). After cooling to room temperature and
diluting with MeOH several times to remove any in-
organic and organic impurities, it was filtered. The
dark-blue crude product was treated several times
with MeCN and filtered off. It was then successively
washed with MeOH, diethyl ether and dried, and fur-
ther purified by column chromatography with silica
gel (eluent: CHCl3:MeOH; 10:1, and then THF) and
dried in vacuo. The desired compound is moderately
soluble in CHCl3 and soluble in acetone, THF, DMF,
DMSO, and quinoline.
Yield: 0.25 g (40%); mp >200◦C; Anal. Calcd
for C56H16F16N8S4 (1232 g/mol): C, 54.55; H, 1.30;
N, 9.09. Found: C, 53.88; H, 1.26; N, 8.92%. FTIR
(KBr) ν (cm−1): 3290 (NH), 3053 cm−1 (w, Ar H,
broad), 1627 (w), 1603 (C C), 1490 (st), 1431, 1377,
1309 (st, C F), 1234 (Ar S Ar), 1176, 1109, 1068,
1
916 (st), 889, 848, 740, 711.; H NMR (DMSO-d6) δ:
8.32 (s, br, H, ortho to Ar C S), 8.12 (dd, br, H,
ortho to CN) , 7.94 (dd, br, H, meta to CN), 6.72
(ortho to Ar C F), −1.54 (2H, br, core NH); UV–
vis (DMSO), λmax (nm): 703 (Qx), 671 (Qy), 644 (agg),
614, 342(B). MS (MALDI–TOF, CHCA as matrix) m/z:
1233 [M + H]+.
Yield: 0.196 g (32%); mp >200◦C; Anal. Calcd for
C56H16F16N8S4Cu (1295.5 g/mol): C, 51.88; H, 1.22; N,
8.64. Found: C, 51.13; H, 1.21; N, 8.01%. FTIR (KBr)
ν (cm−1): 3060 cm−1 (w, Ar H, broad), 1627 (w) 1602
(C C), 1483 (st), 1434 (st, C F), 1380, 1342, 1309,
1176 (Ar S Ar), 1142 (st), 1097, 984, 916 (st, Ar F,
bending), 828.; UV–vis (DMSO), λmax (nm): 678 (Q),
647 (agg), 613, 351 (B); MS (MALDI–TOF, Ditranol
as matrix) m/z (100%): 1232.25 [M + H]+.
2,9,16,23-Tetrakis-4ꢀ-(2,3,5,6-
tetrafluorophenylthio)-
phthalocyaninatozinc(II) 3
A mixture of compound 1 (0.10 g; 0.32 mmol) anhy-
drous Zn (O2CMe)2 (0.015 g; 0.082 mmol), dry quino-
line (2 mL), and DBU (0.05 mL) to a sealed tube was
Heteroatom Chemistry DOI 10.1002/hc

Tetrakis-Phthalocyanines Bearing Electron-Withdrawing Fluoro Functionality 271
2,9,16,23-Tetrakis-4ꢀ-(2,3,5,6-
tetrafluorophenylthio)-
phthalocyaninatocobalt(II)Co(Pc) 5
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¨
O. Polyhedron 2002, 21, 255.
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Chem 2004, 135, 1167.
[17] Bench, B. A.; Brennessel, W. W.; Lie, H-J.; Gorun,
S. M. Angew Chem, Int Ed 2002, 41, 750.
A mixture of compound 1 (0.10 g; 0.32 mmol), an-
hydrous CoCl2 (0.01 g; 0.08 mmol; left one night in
oven at 110◦C), and DBU (0.05 mL) in dry quinoline
was heated to 180◦C under N2 atmosphere for 8 h
(1.00 mL). A similar preparation method to that used
for compound 3 was used to obtain blue powder of
5. Compound 5 is moderately soluble in CHCl3 and
DCM, and soluble in acetone, THF, DMF, DMSO,
and quinoline.
[18] (a) Noma, N.; Tsuzuki, T.; Shirota, Y. Adv Mater 1995,
7, 647; (b) Meyer, J. P.; Schlettwein, D.; Wo¨hrle, D.;
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Yield: 0.23 g (37%); mp >200◦C; Anal. Calcd for
C56H16F16N8S4Co (1291 g/mol): C, 52.05; H, 1.24; N,
8.68. Found: C, 51.93; H, 1.25; N, 8.34%. FTIR (KBr)
ν (cm−1): 3056 cm−1 (w, Ar H, broad), 1722 (w), 1627
(w), 1606 (C C), 1490 (st), 1434, 1380, 1313, 1234 (st,
C F), (Ar S Ar), 1141, 1101, 929 (st), 893, 748,
711.; UV–vis (THF), λmax (nm): 672 (Q), 632 (agg),
608, 335 (B); MS (MALDI–TOF, Ditranol as matrix)
m/z (100%): 1295.28 [M + H]+.
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Heteroatom Chemistry DOI 10.1002/hc