Synthesis, electrochemical and spectroelectrochemical characterization of novel soluble phthalocyanines bearing chloro and quaternizable bulky substituents on peripheral positions

Article abstract of DOI:10.1016/j.dyepig.2011.07.021

A new phthalonitrile derivative (2), bearing diethylaminophenoxy - and chloro-substituents at peripheral positions was synthesized in this work. Cyclotetramerization of (2) in hexanol gave the desired metal-free (4) and metallophthalocyanines (5-8). These new phthalocyanines (4-8) were converted into water-soluble quaternized products by the reaction with methyl iodide (9-11). The novel compounds have been characterized by using elemental analysis, UV-Vis, FT-IR, ¹H NMR and MS spectroscopic data. The aggregation behaviors of the phthalocyanine complexes were studied in different solvents and concentrations. Electrochemical and spectroelectrochemical characterization of the complexes were also performed in solution. Cobalt phthalocyanine gives both metal-based and ring-based reduction processes in comparison to the complexes having 2H⁺, Zn²⁺, Ni²⁺ and Cu²⁺ metal center which give only ring-based reduction processes. Electrochemical and spectroelectrochemical measurements exhibit that all complexes oxidatively electro-polymerize on the Pt working electrode during repetitive cyclic voltammetry measurements. An in-situ electrocolorimetric method was applied to investigate the color of the electrogenerated anionic and cationic forms of the complexes for possible electrochromatic applications.

Full text of DOI:10.1016/j.dyepig.2011.07.021

Dyes and Pigments 92 (2012) 1005e1017
Contents lists available at ScienceDirect
Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
Synthesis, electrochemical and spectroelectrochemical characterization of novel
soluble phthalocyanines bearing chloro and quaternizable bulky substituents on
peripheral positions
a
b
a,
*
ꢀ
H.R. Pekbelgin Karaoglu , Atıf Koca , Makbule Burkut Koçak
a Department of Chemistry, Istanbul Technical University, TR34469 Maslak, Istanbul, Turkey
b Chemical Engineering Department, Engineering Faculty, Marmara University, TR 34722 Göztepe, Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
A
new phthalonitrile derivative (2), bearing diethylaminophenoxy e and chloro-substituents at
Received 2 June 2011
Received in revised form
22 July 2011
Accepted 27 July 2011
Available online 5 August 2011
peripheral positions was synthesized in this work. Cyclotetramerization of (2) in hexanol gave the
desired metal-free (4) and metallophthalocyanines (5e8). These new phthalocyanines (4e8) were
converted into water-soluble quaternized products by the reaction with methyl iodide (9e11). The novel
compounds have been characterized by using elemental analysis, UVeVis, FT-IR, 1H NMR and MS
spectroscopic data. The aggregation behaviors of the phthalocyanine complexes were studied in different
solvents and concentrations. Electrochemical and spectroelectrochemical characterization of the
complexes were also performed in solution. Cobalt phthalocyanine gives both metal-based and ring-
based reduction processes in comparison to the complexes having 2Hþ, Zn2þ, Ni2þ and Cu2þ metal
center which give only ring-based reduction processes. Electrochemical and spectroelectrochemical
measurements exhibit that all complexes oxidatively electro-polymerize on the Pt working electrode
during repetitive cyclic voltammetry measurements. An in-situ electrocolorimetric method was applied
to investigate the color of the electrogenerated anionic and cationic forms of the complexes for possible
electrochromatic applications.
Keywords:
Phthalocyanine
Diethylaminophenoxy
Water-soluble
Aggregation behavior
Electrochemistry
Spectroelectrochemistry
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
between planar macrocycles, which provides decreasing in the
distances between the macrocycles. The solubility of phthalo-
Phthalocyanines (Pcs) are interesting class of compounds
which exhibit unique optical, electronic, catalytic and structural
properties [1]. These unique properties lead to a great interest in
different scientific and technological areas such as photo-
conducting agents in photocopying devices, chemical sensors,
molecular metals, liquid crystals, non-linear optics and catalysis
[1e3]. In recent years, phthalocyanines have also been successfully
used in photodynamic therapy of cancer (PDT) due to their intense
absorption in the red region (600e800 nm) of the optical spectrum
[4e9]. For such applications a good solubility in polar solvents is
preferred [4,10e13].
cysnines can be improved by introducing of substituents on the
periphery of the molecule, since these substituents increase the
distance between the stacked phthalocyanines [14e29]. The size
and the nature of the substituents are not the only criteria for the
solubility of the substituted phthalocyanines; the change in
symmetry caused by the substituents is also important. Usually,
tetra-substituted phthalocyanines (Pcs) are more soluble than
corresponding octa-substituted Pcs due to the formation of four
constitutional isomers and the high dipole moment that results
from the unsymmetrical arrangement of the substituents on the
periphery [1,17e22]. In this sense, octa-substituted phthalocya-
nines were obtained from disubstituted phthalonitrile derivatives
with two different substituents in the 4- and 5- positions, have
been expected to show similar behavior. This new class of octa-
substituted phthalocyanines is relatively less reported, only a few
well characterized species are known [23e29]. In previous papers,
we described the synthesis of these types of phthalocyanines
[26e28]. In addition, we investigated the reactivity of remaining
chloro group in newly synthesized phthalonitrile to obtain other
Applications of peripherally unsubstituted metal-free and
metallophthalocyanines are limited due their insolubility in most
organic solvents and aqueous media. Phthalocyanines possess
a large conjugated p-system which leads p-stacking (aggregation)
* Corresponding author. Tel.: þ90 212 285 69 64; fax: þ90 212 285 63 86.
E-mail address: mkocak@itu.edu.tr (M. B. Koçak).
0143-7208/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.dyepig.2011.07.021

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1006
sophisticated differently substituted phthalonitriles such as
bearing bulky diethylmalonate and alkylsulfanyl [27] or dimethy-
laminoethylsulfanyl groups [28] at 4- and 5-positions.
In the present paper, we describe the synthesis and character-
ization of novel phthalocyanines bearing four chloro and four
bulky dialkylaminophenoxy or trialkylaminophenoxy substituents
on the peripheral positions. The latter group was designed to
achieve solubility in water and DMSO [30e36]. The functions of
metallophthalocyanine derivatives are almost exclusively based on
the complexes under study. During the measurements, readings
were taken as a function of time under kinetic control, however
only the color coordinates at the beginning and final of each redox
processes were reported.
2.3. Synthesis
2.3.1. 1-Chloro-3,4-dicyano-6-[3-(diethylamino)phenoxy]benzene
(2)
their electron transfer reactions because of the
p
-electron-conju-
1,2-Dichloro-4,5-dicyanobenzene (1) (0.50 g, 2.50 mmol) was
dissolved in 10.0 cm3 dry DMF at 50 ꢀC, and 3-(diethylamino)
phenol (0.83 g, 5.00 mmol) was added to this solution. After stirring
for 15 min,1.07 g of finely ground anhydrous Na2CO3 (10 mmol) was
added portion wise during 2 h with efficient stirring. The reaction
mixture was stirred under nitrogen at 50 ꢀC for further 96 h. After
being cooled to room temperature, the mixture was poured into
ice/water (100 cm3). The resulting deep brown solid was collected
by filtration and washed with water until the washings were
neutral. The solid was dissolved in AcOEt and washed several times
with aqueous 1 M NaOH and with brine. The organic solution was
dried with Na2SO4 and the solvent was evaporated to give the crude
product. Finally pure product was obtained by chromatography on
silica gel stationary phase with CHCl3:n-hexane (5:1) mixture as
eluent. The final product (2) was soluble in THF, CHCl3, DMF, and
gated ring system periphery of the molecule. It is necessary to
examine the electron transfer behavior of newly synthesized
phthalocyanine complexes in solution in order to study further
applications such as chemical sensors, electrocatalysts, and elec-
trochromic materials. Therefore, in this study, we have also
examined the voltammetric and spectroelectrochemical proper-
ties of these novel phthalocyanines.
2. Experimental
2.1. Chemicals and instrumentation
IR spectra were recorded on a Perkin Elmer Spectrum One FT-IR
(ATR sampling accessory) spectrophotometer, electronic spectra on
a Scinco S-3100 spectrophotometer. 1H NMR spectra were recorded
on Bruker 250 MHz using TMS as internal standard. Mass spectra
were measured on a Micromass Quatro LC/ULTIMA LC-MS/MS
spectrometer. All reagents and solvents were of reagent grade
quality obtained from commercial suppliers. The homogeneity of
the products was tested in each step by TLC. The solvents were
stored over molecular sieves. Anhydrous potassium carbonate
(K2CO3) and sodium carbonate (Na2CO3) were finely ground and
dried at 100 ꢀC. 1,2-Dichloro-4,5-dicyanobenzene (1) was prepared
according to reported procedure [37].
DMSO. Yield: 0.21 g (31%). 1H NMR (CDCl3):
HeAr), 7.13 (s, HeAr), 6.59 (dd, HeAr), 6.30 (t, HeAr), 6.24 (dd,
HeAr), 3.35 (q, OeCH2), 1.17 (t, CH3); IR (
, cmꢁ1): 3077 (HeAr),
2963, 2926 (HeAliphatic), 2236 (C^N), 1565 (Ar C]C), 1272 (Ar
CeN), 1247 (AreOeAr); 13C NMR (CDCl3):
158.78, 154.4, 150.2,
d 7.87 (s, HeAr), 7.26 (t,
n
d
135.03, 131.1, 128.8, 120.5, 115.5, 114.6, 109.7, 105.7, 106.0, 102.8,
44.36, 12.31; Elemental analysis: C18H16ClN3O calculated %: C,
66.36; H, 4.95; Cl,10.88; N,12.90;þO, 4.91; found %: C, 66.48; H, 5.21;
N, 13.09; MS [m/z]: 324 [M ꢁ H] , 290 [M ꢁ Cl]þ. m.p.: 149.4 ꢀC.
2.3.2. 1,2-Dicyano-4,5-bis[3-(diethylamino)phenoxy]benzene (3)
2.2. Electrochemical in-situ spectroelectrochemical and in-situ
electrocolorimetric measurements
The compound 3 was prepared following the procedure
described for 2 starting from 1 (0.83 g, 5.00 mmol) and 3-(dieth-
ylamino)phenol (0.83 g, 5.00 mmol) in 10 cm3 DMF using K2CO3
instead of Na2CO3 as a base. The crude product was precipitated by
pouring the reaction mixture into copious amount of water and was
purified by recrystallization from ethanol. The compound 3 was
soluble in THF, CHCl3, CH2Cl2, DMF, and DMSO. Yield: 25%. 1H NMR
The cyclic voltammetry (CV) and square wave voltammetry
(SWV) measurements were carried out with Gamry Reference 600
potentiostat/galvanostat controlled by an external PC and utilizing
a three-electrode configuration at 25 ꢀC. The working electrode was
a Pt disc with a surface area of 0.071 cm2. 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 TBAP in extra
pure DCM was employed as the supporting electrolyte at
(CDCl3):
HeAr), 6.33 (t, HeAr), 6.25 (dd, HeAr), 3.34 (q, OeCH2), 1.16 (t,
CH3); 13C NMR (CDCl3):
158.55, 154.57, 150.01, 135.26, 131.14,
120.33, 109.72, 108.87, 106.03, 103.18, 44.44, 12.49; IR (
, cmꢁ1):
d 7.83 (s, HeAr), 7.21 (t, HeAr), 7.12 (s, HeAr), 6.56 (dd,
d
n
3076 (HeAr), 2965, 2928 (HeAliphatic), 2234 (C^N), 1564 (Ar C]
C), 1272 (Ar CeN), 1247 (AreOeAr); C28H30N4O2 calculated %: C,
73.98; H, 6.65; N, 12.33; O, 7.04; found %: C, 74.12; H, 6.82; N, 12.39;
MS [m/z]: 454 [M]þ, 439 [M ꢁ CH3]þ, 425 [MeCH3eCH3]; m.p.:
137.5 ꢀC.
a concentration of 0.10 mol dmꢁ3
.
UVeVis absorption spectra and chromaticity diagrams were
measured by an Ocean Optics QE65000 diode array spectropho-
tometer. In-situ spectroelectrochemical measurements were
carried out by utilizing a three-electrode configuration of thin-layer
quartz thin-layer spectroelectrochemical cell at 25 ꢀC. The working
electrode was a Pt gauze semitransparent electrode. Pt wire
counter electrode separated by a glass bridge and a SCE reference
electrode separated from the bulk of the solution by a double bridge
were used. In-situ electrocolorimetric measurements, under
potentiostatic control, were obtained using an Ocean Optics
QE65000 diode array spectrophotometer at color measurement
mode by utilizing a three-electrode configuration of thin-layer
quartz spectroelectrochemical cell. The standard illuminant
A with 2ꢀ observer at constant temperature in a light booth
designed to exclude external light was used. Prior to each set of
measurements, background color coordinates (x, y, and z values)
were taken at open-circuit, using the electrolyte solution without
2.4. General procedures for phthalocyanine derivatives (4e9)
Reaction: A mixture of compound 2 (97.7 mg, 0.3 mmol),
0.075 mmol anhydrous metal salts [CoCl2, 9.7 mg; NiCl2, 9.7 mg;
CuCl2, 10.1 mg; Zn(CH3COO)2, 13.7 mg; NiCl2, 9.5 mg] and catalytic
amount of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) in 2.0 cm3 of
hexan-1-ol was heated with stirring at 160 ꢀC in a sealed glass tube
(10 ꢂ 75 mm) for 24 h under nitrogen. For metal-free phthalocy-
anine no metal salt was required. After cooling to room tempera-
ture the green suspension was precipitated with methanol, filtered,
washed with the same solvent, and finally dried in vacuo. Purifi-
cation: chromotography. Colors: Dark green. Solubility: Extremely
soluble in CHCl3, THF, DMF and DMSO.

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1007
2.4.1. 2,9,16,23-Tetrakis-[3-(diethylamino)phenoxy]-3,10,17,24-
2.4.3. 2,9,16,23-Tetrakis-[3-(diethylamino)phenoxy]-3,10,17,24-
tetrachloro-phthalocyanine (4)
tetrachloro- phthalocyaninato}cobalt (II) (6)
The purification of the crude product was performed by column
chromatography on silica gel (CHCl3 and Hexane 10:1 v/v). Pure
compound 4 was obtained as an isomeric mixture. Yield: 43 mg, 44%;
IR, gmax (cmꢁ1): 3288 (NeH), 3088e3032 (CeH, aromatic)
2967e2925 (CeH aliphatic), 1262e1242 (AreOeAr); UVeVis (CHCl3):
The purification of the crude product was performed by column
chromatography on silica gel as the stationary phase using CHCl3 as
eluent, which gave pure compound 6 as an isomeric mixture. Yield:
63.5 mg, 62%; IR, gmax (cmꢁ1): 3075 (CeH, aromatic) 2966e2926
(CeH aliphatic), 1272e1241 (AreOeAr); UVeVis (CHCl3): lmax (nm)
lmax (nm) (log
3
) ¼ 343 (5.04), 670 (5.18), 705 (5.22); 1H NMR (CDCl3
(log
3
) ¼ 308 (5.02), 616 (4.69), 673 (5.16); C72H64Cl4N12O4Co
d): 8.39e7.92, 7.25e7.31, 6.76e6.54 (ms, AreH, 24H), 3.45e3.43 (m,
calculated %: C, 63.48; H, 4.74; Cl, 10.41; N, 12.34; O, 4.70; Co, 4.33;
found %: C, 63.63; H, 4.82; N, 12.47; MS: (ESI) yielded an isotopic
cluster peak at m/z 1362.3 [M]þ.
NeCH2, 16H), 1.28e1.21 (m, CH3, 24H), ꢁ5.35 (br s, NH, 2H) ppm;
elemental analysis:C72H66Cl4N12O4 calculated %: C, 66.25; H, 5.10; Cl,
10.87; N, 12.88; O, 4.90; found %: C, 66.37; H, 5.19; N, 13.03; MS: (ESI)
yielded an isotopic cluster peak at m/z 1305.5 [M]þ.
2.4.4. 2,9,16,23-Tetrakis-[3-(diethylamino)phenoxy]-3,10,17,24-
tetra-chloro- phthalocyaninato}zinc (II) (7)
2.4.2. 2,9,16,23-Tetrakis-[3-(diethylamino)phenoxy]-3,10,17,24-
tetrachloro- phthalocyaninato}copper (II) (5)
The purification was performed similarly to 4, the pure product
5 was obtained as an isomeric mixture. Yield: 41 mg, 40%; IR, gmax
(cmꢁ1): 3075e3057 (CeH, aromatic) 2964e2919 (CeH aliphatic),
The purification was performed similarly to 6, the pure product
7 was obtained as an isomeric mixture. Yield: 41 mg, 40%; IR, gmax
(cmꢁ1): 3075(CeH, aromatic), 2965e2924 (CeH aliphatic),
1272e1239 (AreOeAr); UVeVis (CHCl3): lmax (nm) (log
3 ) ¼ 355
(4.72), 654 (4.76); 1H NMR (CDCl3
d): 7.87e7.47, 6.97e6.93,
1273e1242 (AreOeAr); UVeVis (CHCl3): lmax (nm) (log
3
) ¼ 342
6.33e6.29 (ms, AreH, 24H), 3.21 (br s, NeCH2, 16H), 1.15e1.09 (m,
CH3e24H) ppm; C72H64Cl4N12O4Zn calculated %: C, 63.19; H, 4.71;
Cl,10.36%; N,12.28%; O, 4.68; Zn, 4.78% found %: C, 63.31; H, 4.78; N,
12.35%; MS: (ESI) yielded an isotopic cluster peak at m/z 1369.5
[M þ H]þ.
(4.90), 623 (4.77), 684 (5.02); C72H64Cl4CuN12O4 calculated %: C,
63.27; H, 4.72; Cl, 10.38; N, 12.30; O, 4.68; Cu, 4.65; found %: C,
63.35; H, 4.75; N, 12.42%; MS: (ESI) yielded an isotopic cluster peak
at m/z 1365.7 [M ꢁ H]þ.
Scheme 1. Synthesis of Pcs 4e8. i. Na2CO3, DMF, 50 ꢀC, 96 h, ii. K2CO3, DMF, 50 ꢀC, 48 h, iii. 1-hexanol, 24 h, 160 ꢀC, DBU iv. 1-hexanol, metal salts, 24 h, 160 ꢀC, DBU.

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1008
2.4.5. 2,9,16,23-Tetrakis-[3-(diethylamino)phenoxy]-3,10,17,
24-tetrachloro- phthalocyaninato}nickel (II) (8)
until free any soluble reactant or side product. Finally, quaternized
phthalocyanine derivatives were dried in vacuo. The colors all of the
quaternized phthalocyanines were dark green.
The purification of the crude product was performed by
column chromatography on silica gel as the stationary phase
using THF as eluent allowed pure compound 8 to be obtained as
an isomeric mixture. Yield: 73.5 mg, 72%; IR, gmax (cmꢁ1): 3076
(CeH, aromatic) 2966e2926 (CeH aliphatic), 1272e1246
2.5.1. {2,9,16,23-tetrakis-[3-(N,N,N-diethylmethylammonium)
phenoxy]-3,10,17,24-tetrachloro- phthalocyaninato}copper (II)
iodide (9)
(AreOeAr); UVeVis (CHCl3): lmax (nm) (log
3
) ¼ 301 (4.89), 677
Yield: 23.29 mg, 59%; IR gmax (cmꢁ1) 3018 (CeH, aromatic),
2921e2919 (CeH, aliphatic) 1243e1208 (AreOeAr); UVeVis
(5.02); C72H64Cl4N12NiO4 calculated %: C, 63.50; H, 4.74; Cl,
10.41; N, 12.34; O, 4.70; Ni, 4.31; found %: C, 63.58; H, 4.79; N,
12.43; MS: (ESI) yielded an isotopic cluster peak at m/z 1363.14
[M þ H]þ.
(H2O): lmax (nm) (log
calculated% C, 63.27; H, 4.72; Cl, 10.38; N, 12.30; O, 4.68; Cu, 4.65;
found %: C, 63.39; H, 4.79; N, 12.43.
3
) ¼ 335 (4.91), 613 (4.95); C72H64Cl4CuN12O4
2.5. General procedures for quaternized phthalocyanine
derivatives (9e11)
2.5.2. {2,9,16,23-tetrakis-[3-(N,N,N-diethylmethylammonium)
phenoxy]-3,10,17,24-tetrachloro-phthalocyaninato}cobalt (II)iodide
(10)
A mixture of phthalocyanine derivative 0.02 mmol [5 (27.3 mg),
6 (27.2 mg), 7 (27.4 mg)], 0,0794 mol (5.59 g) of methyl iodide in
5 cm3 CHCl3 was heated and stirred at 70 ꢀC for 5 days in the dark.
The resulting green suspension was cooled to ambient temperature
and then filtered off. The precipitate was washed with hot CHCl3
Yield: 24.66 mg, 64%; IR
2976e2941 (CeH, aliphatic), 1244e1209 (AreOeAr); UVeVis
(H2O): lmax (nm) (log 320 (4.91), 619 (5.01);
g
max (cmꢁ1) 3011 (CeH, aromatic),
3 )
¼
C76H76Cl4CoI4N12O4 calculated %: C, 47.30; H, 3.97; Cl, 7.35; I, 26.30;
N, 8.71; O, 3.32; Co, 3.05; found %: C, 47.43; H, 4.03; N, 8.83%.
Scheme 2. Isomers of phthalocyanines 4e8.

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1009
2.5.3. {2,9,16,23-tetrakis-[3-(N,N,N-diethylmethylammonium)
phenoxy]-3,10,17,24-tetrachloro- phthalocyaninato}zinc
(II)iodide (11)
All the synthesized compounds are new except 3, which was
previously reported in the literature [38]. Elemental analysis results
and the spectral data (FT-IR 1H NMR, ESI-MS and UVeVis) for all
new products were consistent with the assigned formulations.ꢁIR1
Yield: 24.66 mg, 64%; IR gmax (cmꢁ1) 3035 (CeH, aromatic),
2976e2941 (CeH, aliphatic) 1244e1203 (AreOeAr); UVeVis
spectrum of 2 indicated the aromatic CeOeC groups at 1247 cm
,
(H2O): lmax (nm) (log
N12O4Zn calculated %: C, 47.14; H, 3.96; Cl, 7.32; I, 26.22; N, 8.68; O,
3.30; Zn, 3.38; found %: C, 47.28; H, 4.05; N, 8.80%.
3
) ¼ 341 (5.01), 629 (4.99); C76H76Cl4I4
the C^N groups at 2236 cmꢁ1, aliphatic groups at 2963e2926 cmꢁ1
and aromatic groups at 3077 cmꢁ1 by intense bands. In addition,
the appearance of intense new absorptions at 1272e1247 cmꢁ1 in
the spectra attributable to AreOeAr groups confirmed the
proposed structure of the compound 2 when compared with the IR
spectrum of 1,2-dichloro-4,5-dicyanobenzene (1) [25,28,34,35].
After conversion of the dinitrile 2 to the phthalocyanines, the
sharp C^N vibration around 2236 cmꢁ1 disappeared. IR spectra of
all the phthalocyanine derivatives showed aromatic CeOeC peaks
at 1272e1239 cmꢁ1. The IRspectra of the phthalocyanines 4e8 are
very similar, with the exception of the metal-free 4 showing an NH
stretching band peak at 3288 cmꢁ1 due to the inner core. The NH
proton of metal-free phthalocyanine was also identified in the 1H
-
3. Results and discussion
3.1. Synthesis and characterization
The first step in the synthesis of the target phthalocyanines 4e8
was to obtain 1-chloro-3,4-dicyano-6-(3-(diethylamino)phenoxy)
benzene (2). The compound 2 was prepared from 1,2-dichloro-4,5-
dicyanobenzene by displacement of the one chloro group of 2 with
the OH function of the 3-(diethylamino)phenol at 50 ꢀC in dry DMF
under N2 atmosphere for 96 h (Scheme 1). In the present study,
when Na2CO3 was used as a base, the chloro groups were partially
substituted and 1-chloro-3,4-dicyano-6-(3-(diethylamino)phe-
noxy)benzene (2) was obtained. However, in the case of K2CO3,
both chloro groups were substituted and 1,2ebis(3-(diethylamino)
phenoxy)-4,5-dicyanobenzene (3) was obtained. The synthesis of
the compound 3 by using K2CO3 has recently been described in the
literature [38]. The compound 2 was obtained in this study by using
Na2CO3 because of the probable template effects of Kþ and Naþ
ions. [39]. Cyclotetramerization of dinitrile derivative 2 in the
presence of 1,8-diazobicyclo[5,4,0]- 7 eene and/or anhydrous
metal salts [CuCl2, CoCl2, Zn(CH3COO)2, NiCl2] at 160 ꢀC in 1-
hexanol for 24 h, under a nitrogen atmosphere gave metal-free
and metallophthalocyanines (4e8), respectively (Scheme 1).
Phthalonitrile derivatives containing two different substituted
groups afford the isomer mixture of phthalocyanine derivatives. In
all cases, a mixture of four possible structural isomers is obtained.
We expect that metal-free (4) and metallophthalocyanines (5e8)
were obtained as a statistical mixture of four regioisomers owing to
the various possible positions of the diethylaminophenoxy and
chloro side-chains relative to one another (Scheme 2). The four
probable isomers can be obtained with molecular symmetries
(D2h:Cs:C2v:C4h in ratio of 1:1:2:4).To the best of our knowledge, the
successful separation of these four isomers with common column
chromatography or recrystallization has not been achieved in the
literature. No attempt was made to separate the isomers of 4e8.
When the whole molecule is taken into account, it is not possible to
define D4h for all the isomers of metallophthalocyanines. Similar
argument is also true for the metal-free derivative and describing it
with D2h symmetry is ambiguous. Therefore, it should be clear that
the products are a mixture of isomers and D4h and D2h symmetry
could be pronounced only when the inner phthalocyanine core is
taken into account. The newly synthesized phthalocyanines were
obtained purely after column chromatography on silica gel by using
THF, CHCl3, CHCl3/Hexane mixtures as the eluents. These bulky
substituents are efficient to hinder the aggregation of macrocycle
[14e21,24e27]. The dark green products are extremely soluble in
polar and apolar solvents such as CHCl3, DCM, THF, DMF and DMSO.
However the complex 5 is not soluble in DMSO, although others are
soluble. Quaternarization of metallophthalocyanines 5e7 was
achieved by reaction with excess methyl iodide as quaternarization
agent in chloroform as solvent at 70 ꢀC in the dark for 5 days. The
hygroscopic phthalocyanine products 9e11 with four quaternary
ammonium groups were obtained in high yields (w60%) (Fig. 1).
Quaternized products were soluble in water and DMSO, but insol-
uble in chloroform.
NMR spectrum with a broad peak at
d
¼ 5.35 ppm, presenting the
typical shielding of inner core protons, which is common feature of
the 1H NMR spectra of metal-free phthalocyanines. No major
changes in the IR spectra were found after quaternarization.
1H NMR spectra of phthalonitrile (2), metal-free phthalocyanine
(4) and the phthalocyanine with diamagnetic metal ion in the core
(7) were consistent with proposed structures. In the 1H NMR
spectrum of 2 in CDCl3, the aromatic protons appear as two singlets
at 7.87 and 7.13 ppm, two triplets at 7.26 and 6.30 ppm, two doublet
doublets at 6.59 and 6.24 ppm. Aliphatic CH2 and CH3 protons of
ethylaminophenoxy groups appear as a quartet at 3.35 and a triplet
at 1.17 ppm, respectively.
The 1H NMR spectrums of 4 and 7 is somewhat broader than the
corresponding signals in the dinitrile derivative 2. It is likely that
the broadness results from both chemical exchanges caused by
aggregationedisaggregation equilibria and the fact that the
obtained product in this reaction is a mixture of four positional
isomers which are expected to show chemical shifts only slightly
different from each other.
Fig. 1. Quaternized phthalocyanines 9e11.

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1010
3.2. Ground-state electronic absorption spectra
UVeVis spectra are especially fruitful to establish the structure
of the phthalocyanines. The phthalocyanines exhibit typical elec-
tronic spectra with two strong absorption regions, one of them is in
the visible region at 600e700 nm (Q band) and the other one is in
the UV region at about 300e350 nm (B band), both correlate to
pep*transitions. Aggregation is usually depicted as a co-planar
association of rings progressing from monomer to dimer and
higher order complexes and affects the shape of the Q band.
Aggregation is dependent on the concentration, nature of the
solvent, nature of the substituents, complexed metal ions, and
temperature [40]. The ground-state electronic spectra of all met-
allophthalocyanines (5e8) in chloroform display intense Q bands in
the visible region around 654e705 nm with relatively sharp
absorption peaks and almost no shoulder on the higher energy side,
which would correspond to aggregated species and the B bands in
the near UV region, around 301e355 nm (Fig. 2) [18,22,28]. In
chloroform, the metal-free phthalocyanine (4) gives a split Q band
in the visible region (670 and 705 nm) as a result of the D2h
symmetry [18,27].
UVeVis spectra of the quaternized metallophthalocyanines
(9e11) in H2O show some differences from those of corresponding
non quaternized derivatives (5e8) in chloroform (Fig. 3). The Q
bands are present as a shoulder, while the absorption of the
aggregated species is the main band as a result of solvent effect [18].
In this study, the aggregation behavior of 7 was also investigated
at different concentrations in chloroform (Fig. 4). As shown in the
figure, the Q band increases in intensity with increasing in the
concentration of 7 and any new band were observed due to the
aggregated species [41,42]. BeereLambert Law was obeyed for 7 in
the concentrations in the range 4e14 ꢂ 10ꢁ6 mol dmꢁ3 (Fig. 4).
The electronic absorption of compound 5 and 7 in different
organic solvents, such as tetrahydrofuran, dimethyl formamide,
chloroform, dimethyl sulfoxide and toluene, are shown in Figs. 5and
6, respectively. While complex 7 showed aggregation in DMSO, the
complex 5 showed aggregation in DCM, DMF, and DMSO. The
complex 5 is not soluble in DMSO. To observe the aggregation
Fig. 3. UV spectra of QCuPc (9), QCoPc (10) and QZnPc (11) (8 ꢂ 10ꢁ6 M in H2O).
behavior of 5 in DMSO, first of all it was dissolved in DCM, and then
DCM was removed by purging with N2 and then DMSO was added.
DMSO solution of the complex 5 was prepared whit this procedure.
Fig. 6 (as inset) gives the aggregation behavior of 5 in DMSO at
different concentrations. As shown in this figure, the complex 5
aggregates in high extend and the aggregation band at 614 nm is
higher than that of the Q band at 685 nm assigned to the monomeric
species at all concentrations. It is obvious that the Q band positions
of the complexes vary as the solvent is changed. In general, the red
shift of the Q band increases with the ascending refractive index of
the solvent. In our study, the bathochromic shift of the Q band due to
the solvent for compound 7 increased in the following order:
tetrahydrofuran < dimethyl formamide < chloroform < dimethyl
Fig. 2. UV spectra of H2Pc (4), CuPc (5), CoPc (6), ZnPc (7) and NiPc (8) (6 ꢂ 10ꢁ6 M in
Fig. 4. Absorption spectra of ZnPc (7) in CHCl3 at different concentrations: 14 ꢂ 10ꢁ6
CHCl3).
(A), 12 ꢂ 10ꢁ6 (B), 10 ꢂ 10ꢁ6 (C), 8 ꢂ 10ꢁ6 (D), 6 ꢂ 10ꢁ6 (E) and 4 ꢂ 10ꢁ6 (F) mol dmꢁ3
.

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1011
Fig. 7. Plot of the Q band frequency of ZnPc (7) against (n2 ꢁ 1)/(2n2 þ 1), where n is
Fig. 5. Absorption spectra of ZnPc (7) in different solvents (6 ꢂ 10ꢁ6 mol dmꢁ3).
the refractive index of the solvent.
sulfoxide < toluene. The electronic absorption spectra of 7 in these
solvents were analyzed by using the method described originally by
Bayliss [43]. Fig. 7 displays a plot of the Q band frequency versus the
function (n2 ꢁ 1)/(2n2 þ 1), where n is the refractive index of the
solvent. The positions of the Q bands in these solvents show almost
a linear dependence on this function. This linearity suggests that the
shifts are mainly due to the solvation and not to a ligation effect [44].
TBAP electrolyte system on a Pt working electrode. Table 1 lists the
assignments of the redox couples and estimated electrochemical
parameters including the half-wave peak potentials (E1/2), ratio of
anodic to cathodic peak currents (Ip,a/Ip,c), peak to peak potential
separations (
reduction processes (
values are in agreement with the reported data for redox processes
of the metallophthalocyanine complexes [18,45e50]. E1/2 reflects
DEp), and difference between the first oxidation and
D
E1/2). Peak to peak separations, E1/2 and E1/2
D
D
the HOMOeLUMO gap for metal-free Pcs and it is related with
HOMOeLUMO gap in MPc species having redox inactive metal
center. Presence of four dialkylaminophenoxy substituents on the
complexes causes oxidative electro-polymerization of the
complexes on the working electrode. When compared with the
tetra-substituted dialkylaminophenoxy derivatives of the
complexes [38], redox couples of the complexes studied here shift
to the negative potentials due to the electron releasing ability of the
chloro-substituents. Although the complexes aggregate in less
extent and the aggregation changes with the solvent of the
complexes, all complexes indicate aggregation behavior in DCM/
TBAP electrolyte system during the electrochemical and spec-
troelectrochemical measurements. This behavior of the complexes
may be due to the very high concentration used during electro-
chemical (5.0 ꢂ 10ꢁ4 mol dmꢁ3) and spectroelectrochemical
(1.0 ꢂ 10ꢁ3 mol dmꢁ3) measurements. Presence of TBAP salt may
also affect the aggregation of the complexes.
3.3. Voltammetric characterization
The CVs and SWVs of the phthalocyanines (H2Pc (4), CuPc (5),
CoPc (6), ZnPc (7), and NiPc (8)) were obtained in deaerated DCM/
Fig. 8 shows the CV and SWV of H2Pc (4).Within the electro-
chemical cathodic window of DCM/TBAP in CV measurements;
H2Pc illustrates two reversible one-electron reductions at ꢁ0.74
and ꢁ0.99 V at 0.100 Vsꢁ1 scan rate. Third reduction process is
recorded at ꢁ1.88 V with SWV. For the reduction couples, anodic to
cathodic peak separations (DEp) changed from 60 to 125 mV with
the scan rates from 10 to 500 mVꢁ1 support reversible electron
transfer. Reversibility is illustrated by the similarity in the forward
and reverse SWVs (Fig. 8b) [51]. Unity of the Ipa/Ipc ratio at all scan
rate and linear variation of the Ipc with square root of the scan rates
indicated the purely diffusion controlled electron transfer mecha-
nism of the processes. During the anodic CV scans, two intense
redox peaks are recorded at 0.94 and 1.13 V. Peak currents of these
processes increase with the repetitive CV cycles, while a new redox
Fig. 6. Absorption spectra of CuPc (5) in different solvents (6 ꢂ 10ꢁ6 mol dmꢁ3). (inset:
absorption spectra of CuPc (5) in DMSO at different concentrations).

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Table 1
Voltammetric data of the complexes with the related metallophthalocyanines for comparison.
III/MII
MII/MI
Ring
reductions
DE1/2
d
Complex
Ring/Substituent
Oxidations
M
H2Pc
E1/2 vs. SCEa
1.13e,f
e
0.94
0.84
0.85
0.88
0.54
e
e
e
e
e
e
e
e
e
e
e
e
e
ꢁ0.74
62
0.99
ꢁ0.86
140
0.95
ꢁ0.83
160
0.87
ꢁ0.82
144
ꢁ0.99
65
ꢁ1.88e
1.68
1.70
1.68
1.70
0.77
D
Ep (mV)b
e
e
e
c
Ipa/Ipc
e
e
e
0.97
ꢁ1.17
135
0.97
ꢁ1.14
70
0.95
ꢁ1.31
165
0.77
e
e
NiPc
CuPc
ZnPc
CoPc
E1/2 vs. SCEa
1.21e,f
e
e
ꢁ1.48e
D
Ep (mV)b
e
e
e
e
c
Ipa/Ipc
e
e
e
E1/2 vs. SCEa
1.06e,f
e
e
ꢁ1.93e
D
Ep (mV)b
e
e
e
e
e
e
e
e
e
e
e
c
Ipa/Ipc
e
e
E1/2 vs. SCEa
1.05e,f
e
e
D
Ep (mV)b
e
e
e
c
Ipa/Ipc
e
e
0.91
ꢁ1.37
130
E1/2 vs. SCEa
0.72
1.11f
ꢁ0.20 (ꢁ0.52)
D
Ep (mV)b
300
0.98
70
e
c
Ipa/Ipc
0.97
0.62
e
a
E1/2¼(Epa þ Epc)/2 at 0.100 Vsꢁ1
.
.
b
c
D
Ep ¼ jEpa ꢁ Epcj at 0.100 Vsꢁ1
Ipa/Ipc for reduction, Ipc/Ipa for oxidation processes at 0.100 Vsꢁ1 scan rate.
d
DE1/2
¼
D
E1/2 (first oxidation) ꢁ E1/2 (first reduction) ¼ HOMOeLUMO gap for metallophthalocyanines having electro-inactive metal center (metal to ligand (MLCT) or
D
ligand to metal (LMCT) charge transfer gap for MPc having redox active metal center).
e
The process is recorded with SWV.
Assignment of this process could not be performed by in-situ spectroelectrochemistry due to the polymerization.
f
process is recorded at 0.60 V with increasing current intensity
(Fig. 8a inset). These voltammetric data indicates the electro-
polymerization of the complex on the working electrode during
the oxidation reaction. Polymerization of the complex during the
anodic scan affects the behavior of the complex during the reduc-
tion processes. While the complex give reversible diffusion
controlled reduction processes during the cathodic scans, a new
intense wave is recorded at ꢁ0.81 V after the anodic polymerization
process. This new wave shifts to the negative potentials and gets
broad with decreasing in current intensity during the repetitive CV
cycles. At the same time, reduction processes of H2Pc disappear
when polymerization continues. After the fourth CV cycles the peak
currents of the waves starts to decrease, which may due to the
decreasing the conductivity of the polymer on the working elec-
trode due to the increasing of the film thickness. The working
electrode coated with polymerized H2Pc gave the redox responses
assigned to the electropolimerized complex in the complex-free
DCM/TBAP electrolyte system. The peak current of the redox
processes increased linearly as a function of the scan rate. These
data support the polymerization of the complex on the working
electrode. Assignments of the redox couples were performed by
spectroelectrochemical measurements given below.
Complexes carrying redox inactive metal centers (CuPc (5),
ZnPc (7), and NiPc (8)) illustrate very similar voltammetric
responses. All of these complexes give three quasi-reversible,
diffusion controlled, and ligand-based reduction processes during
the cathodic scans and electro-polymerize on the working elec-
trode during the anodic scans. When we compared electrochemical
responses of these complexes, the redox couples shift to the posi-
tive potentials as a function of the effective nuclear charge of the
central metal ions. Effective nuclear charge order is
H2Pc > ZnPc > CuPc > NiPc. Electron transfer potentials are in the
same order with the effective nuclear charge order. Fig. 9 shows the
CV and DPV of CuPc (5) as a representative of these complexes.
CuPc illustrates two quasi-reversible one-electron reductions
at ꢁ0.83 and ꢁ1.14 V at 0.100 Vsꢁ1 scan rate. Third reduction
process is recorded at ꢁ1.93 V with SWV. For the first reduction
couple, the cathodic peak splits into two waves due to the aggre-
gation of the complex. Aggregation of the complex decreases the
reversibility of the process due to a possible following chemical
Fig. 8. a) CVs of H2Pc (5.0 ꢂ 10ꢁ4 mol dmꢁ3) at various scan rates on Pt in DCM/TBAP
(inset: CVs recorded with repetitive CV cycles at 0.100 Vsꢁ1 scan rate). b) SWV of H2Pc,
SWV parameters: pulse size ¼ 100 mV; Step Size: 5 mV; Frequency: 25 Hz.

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Fig. 10. a) CVs of CoPc (5.0 ꢂ 10ꢁ4 mol dmꢁ3) at various scan rates on Pt in DCM/TBAP
(inset : CVs recorded with repetitive CV cycles at 0.100 Vsꢁ1 scan rate). b) SWV of CoPc,
SWV parameters: pulse size ¼ 100 mV; Step Size: 5 mV; Frequency: 25 Hz.
Fig. 9. a) CVs of CuPc (5.0 ꢂ 10ꢁ4 mol dmꢁ3) at various scan rates on Pt in DCM/TBAP;
(inset: SWV of CuPc, SWV parameters: pulse size
¼
100 mV; Step Size: 5 mV;
Frequency: 25 Hz b) CVs recorded with repetitive CV cycles within the whole potential
window of the electrolyte at 0.100 Vsꢁ1 scan rate (inset: CVs recorded with anodic
repetitive CV cycles).
during CV measurements, CoPc undergoes two reversible one-
electron reduction processes at ꢁ0.20 and ꢁ1.37 V. For the first
reduction couple, the anodic to the cathodic peak separations (DEp)
reaction; aggregationedisaggregation equilibrium. Second reduc-
tion couple is both electrochemically and chemically reversible
with respect to the DEp and Ipa/Ipc ratio change as a function of the
changed from 62 to 115 mV with the scan rates from 10 to
500 mVꢁ1 support the reversible electron transfer character of the
process. Reversibility is illustrated by the similarity in the forward
and reverse SWVs (Fig. 10b) [51]. While the Ipa/Ipc ratio of first
reduction couple is unity at slow scan rates. It deviates from the
unity with the increasing scan rates, which indicate existence of
a kinetic control after the first reduction process. The wave (Ra)
at ꢁ0.52 V recorded at high scan rates supports the existence of this
kinetic control. While the Ra process is invisible at slow scan rates,
its peak current increases more than that of RI with the increasing
scan rates. This wave disappeared with diluting of the solution.
These data indicate the aggregation of the complex and aggregated
species reduce at ꢁ0.52 V. Aggregationedisaggregation equilib-
rium is affected with the scan rate and concentration; whose
responses are recorded as changing in the peak current of the Ra
process. Second reduction process has a quasi-reversible electron
transfer character. During the anodic scans, similar electro-
polymerization process also recorded with CoPc like other
complexes (Fig. 10a inset). Due to the metal-based oxidation, three
oxidation processes are recorded with CoPc during the first CV
cycle, while there are two waves for other complexes. Polymeri-
zation of the complex proceeds continuously and the redox peaks
shift to the more positive potential during the continuous cycles.
Assignments of the redox couples are performed by spectroelec-
trochemical measurements given below.
scan rate. Reversibility is illustrated by the similarity in the forward
and reverse SWVs (Fig. 9a inset) [51]. During the anodic potential
scans, CuPc electro-polymerizes on the working electrode likes
H2Pc. (Fig. 9b). Similar voltammetric responses are recorded with
all complexes but while polymerization diminishes after the fourth
cycle for H2Pc, the process continues until the eighth cycles for
CuPc and continuously for ZnPc and NiPc. Changing the potential
window of the CV cycles affects the mechanism of the polymeri-
zation reaction. When only positive potentials are scanned (Fig. 9b
inset), the wave at 0.87 V increases with positive shift as a function
of continuous CV cycles. At the same time a new broad wave at
around 0.40 V in addition to the waves at 0.90 and 0.77 V are
observed with increasing current intensity as a function of CV cycle.
However when both the cathodic and anodic potentials are scan-
ned, two extra waves at 0.46 V (with positive shift) and ꢁ0.90 V
(with negative shift) in addition to other redox processes are
recorded (Fig. 9b). These data indicates that polymerization
mechanism changes with the potential window of the CV scans.
Assignments of the redox couples are performed by spectroelec-
trochemical measurements given below.
Fig. 10 represents the CV and DPV of CoPc (6) in DCM/TBAP
electrolyte. Within the electrochemical window of DCM/TBAP

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3.4. In-situ spectroelectrochemical measurements
Spectroelectrochemical studies were employed to confirm the
assignments in the CVs of the complexes. H2Pc, ZnPc, NiPc, and
CuPc have redox inactive Pc centers thus indicate ring-based
characters for all redox couples. To represent in-situ spectroelec-
trochemical response of the metal-free phthalocyanines, spectral
chances of H2Pc during the controlled potential application at the
redox potentials are given in Fig. 11. For the metal-free phthalocy-
anines, the symmetry is D2h and therefore there are two sharp
bands (split Q band) at 663 and 697 nm [45,48e50,52,53]. Due to
the presence of aggregation and/or due to performing the
measurements with high concentration, splitting of the Q band is
shadowy and an aggregation band is recorded at 663 nm in high
intensity. When the working electrode is polarized at ꢁ1.00 V,
[H2Pc2ꢁ] is one-electron reduced to form [H2Pc3ꢁ 1ꢁ
anion. During
]
the reduction of [H2Pc2ꢁ] at constant potential application, a sharp
single band is recorded at 677 nm instead of the split Q band. At the
same time, a new band is recorded at 400 nm, while the intensity of
the B band decreases with shifting from 334 to 341 nm (Fig. 11a).
During this process, well-defined isosbestic points are recorded at
278, 350, 476, 654, and 697 nm, which demonstrate that the
reduction proceeds cleanly in deoxygenated DCM to give a single,
reduced species. Rollmann and Iwamoto [53] and Koca et al. [18,54]
also reported similar spectroscopic changes for one-electron
reduction of H2Pc complexes. It was mentioned that there might
be a symmetry change from D2h to D4h because of the substitution
of central hydrogens by the cations of supporting electrolyte. It was
shown that the pair of excited states which usually give rise to the Q
band doubling in the [H2Pc3ꢁ 1ꢁ
species, is still present but the
]
states are too close together to be resolved. During the potential
application at ꢁ1.20 V, [H2Pc3ꢁ 1ꢁ
]
is one-electron reduced to form
[H2Pc4ꢁ 2ꢁ
dianion (Fig. 11b). Spectroscopic changes show a band,
]
which tries to increase at around 510 nm. But due to the decom-
position of the reduced species, all band decreases in intensity.
During the oxidation of H2Pc at 1.20 V applied potential, intensity of
all bands decrease in intensity (Fig. 11c). These spectroscopic
changes may due to the electro-polymerization of the complex on
the working electrode which diminishes concentration of the
species in the bulk solution. The color of the neutral H2Pc was
recorded as greenish blue (x ¼ 0.2597 and y ¼ 0.3445). Instinct
color changes were not recorded between the electrogenerated
forms of the complexes.
Fig. 12 shows the spectral chances of CuPc as a representative of
MPc’s having redox inactive metal center under applied potential.
Before any potential application, the band at 626 nm results from
the aggregated species, which support the aggrega-
tionedisaggregation equilibrium recorded by the CV and SWV
measurements. Under open-circuit potential, an intense aggrega-
tion band is recorded at 626 nm in addition to the common Q band
at 677 nm and the B band at 330 nm in the spectra of the complex.
During the controlled potential reductions of CuPc at ꢁ0.90 V
potential applications, two distinct spectral changes are recorded.
First of all, while the Q band at 677 nm decreases in intensity, the
band assigned to the aggregated species increases due to the
shifting of the aggregationedisaggregation equilibrium under
applied potential (from red to black spectrum in Fig. 12a). At the
same time, new bands at 587 and 950 nm are recorded. Then while
the Q band and the band at 626 nm decrease in intensity, a new
band is recorded at 576 nm potential (from black to blue spectrum
in Fig. 12a). During this electrochemical reduction, isosbestic points
are observed at around 320, 438, and 757 nm with oscillation, and
various isosbestic points at around 500 nm are recorded. These data
demonstrates that the reduction process gives more than a single
product, which may be reduced, aggregated and disaggregated
Fig. 11. In-situ UVevis spectral changes of H2Pc. a) Eapp ¼ ꢁ0.50 V b) Eapp ¼ ꢁ1.50 V c)
Eapp ¼ 0.70 V.

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1015
Fig. 12. In-situ UVevis spectral changes of CuPc. a) Eapp ¼ ꢁ0.50 V b) Eapp ¼ ꢁ1.50 V c) Initial part of the spectral changes at Eapp ¼ 0.70 V (inset: final part of the spectral changes at
q
ꢁ1
ꢁ2
,
Eapp ¼ 0.70 V). d) Chromaticity diagram of CuPc. (Each symbol represents the color of electrogenerated species; ,: [CuIIPcꢁ2], B:[CuIIPcꢁ3
]
,
6
: [CuIIPcꢁ3
]
:[CuIIPcꢁ1 þ1).
]
copper(I) species. However, general trend of the spectroscopic
Fig. 13 represents in-situ UVevis spectral changes and in-situ
recorded chromaticity diagram of CoPc (6) in DCM/TBAP during
the potential application at the potentials of the redox processes.
Before any potential application, an aggregation band is recorded at
626 nm in addition to the Q band of the monomeric species at
670 nm. During the first reduction process, two different spectral
changes are recorded. First of all, due to the change in the aggre-
gationedisaggregation equilibrium, a single broad band is recorded
at 655 nm instead of the bands at 626 and 670 nm. At the same time
a new band starts to increase at 474 nm. These spectral changes
support the reduction of the aggregated species. Then while the
band at 655 nm shifts to 706 nm, the new band at 474 nm enhances
in current intensity. These spectral changes indicated the metal-
based reduction of both monomeric CoPc species and charac-
changes indicates a Pc ring reduction process and assigns the first
reduction process (couple RI) to [CuIIPcꢁ2]/[CuIIPcꢁ3 ꢁ1
process
]
[46,49,55e57]. Spectroscopic changes under controlled potential
application at ꢁ1.20 V support the further reduction of the mon-
oanionic [CuIIPcꢁ3 ꢁ1 species to [CuIIPcꢁ4 ꢁ2
] (Fig. 12b). Decreasing
]
of the Q band intensity without shift and observation of new bands
at 536, 800, and 897 nm are characteristics of the ring reduction
process. During the oxidation of CuPc (Fig. 12c inset) at 0.90 V, the
absorption of all band decrease in intensity which indicates the
polymerization of the complex on the working electrode. Under
applied potential at 1.30 V, the Q band at 677 nm and its shoulder at
627 nm decrease in intensity without shift, while new bands at 525
and 825 nm appears with increasing in intensity (Fig. 12c). These
changes are typical of the ring-based oxidation and assigned to
terize formation of the [CoIPcꢁ2 1ꢁ
species under the applied
]
[CuIIPcꢁ2]/[CuIIPcꢁ1 þ1
]
process [46,49,55e57].
potential at ꢁ0.40 V (Fig. 13a) [54e60]. This process gives a color
changes from blue (x ¼ 0.2117 and y ¼ 0.2852) to greenish yellow
(x ¼ 0.3798 and y ¼ 0.3984) as shown in the chromaticity diagram
(Fig. 13d). As shown in Fig. 13b, the Q band at 706 nm decreases
without shift while a new broad band is recorded at 544 nm under
the controlled potential application at ꢁ1.40 V. These spectral
changes are characteristic of the ring-based reduction of
The color change of the complexes during the redox processes
were recorded using in-situ colorimetric measurements. Without
any potential application, the solution of CuPc is greenish blue
(x ¼ 0.2158 and y ¼ 0.3273) (Fig. 12d). As the potential is stepped
from 0 to ꢁ0.90 V, the color of the neutral [CuIIPcꢁ2] start to
changes and dark blue color (x ¼ 0.2244 and y ¼ 0.1664) of mon-
oanionic form of [CuIIPcꢁ3 ꢁ1
]
is obtained at the end of the first
reduction. Similarly color of the dianionic species, [CuIIPcꢁ4 ꢁ2
is
recorded as purple (x ¼ 0.3648and y ¼ 0.2666). Monocationic
species, [CuIIPcꢁ1 þ1
has light violet color (x ¼ 0.2927 and
y ¼ 0.319).
[CoIPcꢁ2 1ꢁ species to [CoIPcꢁ3 2ꢁ
] ] species. Fig. 13c represents the
]
spectral changes during the first oxidation process of the complex.
During 0.80 V potential application, while the intensity of the Q
band increases, the band at 626 nm decreases in intensity. At the
same time a new band is recorded at 370 nm. These spectral
]

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1016
Fig. 13. In-situ UVevis spectral changes of CoPc. a) Final part of the spectral changes at Eapp ¼ ꢁ0.50 V (Initial part of the spectral changes at Eapp ¼ ꢁ 0.50 V). b) Eapp ¼ ꢁ1.50 V c)
q
ꢁ1
ꢁ2
,
Eapp ¼ 1.00 V d) Chromaticity diagram of CoPc. (Each symbol represents the color of electrogenerated species; ,: [CoIIPcꢁ2], B:[CoIPcꢁ2
]
,
6
: [CoIPcꢁ3
]
:[CoIIPcꢁ1 þ1).
]
changes indicate the ligand-based process and changing of the
aggregationedisaggregation equilibrium during the oxidation
process. Under applied potential at 1.30 V, intensity of all bands
decreased, which supports electro-polymerization of the complex
on the working electrode. Color changes during the reduction and
oxidation processes are represented in Fig. 13d.
reduction processes and electro-polymerizes during the anodic
scans. Definite determination of the colors of the electrogenerated
anionic and cationic form of the complexes is important to decide
the possible electrochromic application of the complexes.
Acknowledgements
4. Conclusion
This work was supported by the Research Fund of the Istanbul
Technical University and TUBITAK (Project no. 109T163).
As seen in Scheme 1, the reaction between 1,2-dichloro-4,5-
dicyanobenzene and 3-(diethylamino)phenol in the presence of
Na2CO3 as a base gives the compound 2 which is contrary to the
compound 3 obtained using K2CO3. This work has also presented
a comprehensive investigation of solvent effects on the aggregation
of this octa-substituted zinc phthalocyanine complex. The aggre-
gation properties are studied for zinc and copper phthalocyanines in
tetrahydrofuran, dimethyl formamide, chloroform, dimethyl sulf-
oxide, dichloromethane and toluene. The effect of the concentration
on the aggregation properties for complex 7 was also studied in
chloroform. No aggregation was demonstrated in chloroform from
concentration between 14 ꢂ 10ꢁ6 and 4 ꢂ 10ꢁ6 mol dmꢁ3. Vol-
tammetric and spectroelectrochemical studies show that while H,
Zn, Ni and Cu phthalocyanines give ring-based, multi-electron and
reversible/quasi-reversible reduction processes, complexes electro-
polymerize on the working electrode during oxidation reactions.
Similarly cobalt phthalocyanine gives both metal and ring-based,
diffusion controlled, multi-electron and reversible/quasi-reversible
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