Synthesis, H- or J-type aggregations, electrochemistry and in situ spectroelectrochemistry of metal ion sensing lead(II) phthalocyanines

Article abstract of DOI:10.1016/j.poly.2010.09.035

We report, in this study, peripherally 3- and 4-substituted functionalized ionophore ligands (1-3) and their α- and β-tetra polyalcohol substituted lead(II) phthalocyanines M{Pc[S-CH(C₃H ₇)(C₂H₅OH)]₄} (7, 9 and 11) and M{Pc[S-C₆H₁₂(OH)]₄} (8, 10 and 12) which are a mixture of different isomers. The complexes have been fully characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, MS (MALDI-TOF) and UV-Vis spectral data. These complexes induced H-type (face-to-face fashion) or J-aggregate (edge-to-edge) dimers when titrated with AgNO₃ or Na₂PdCl₄ in a THF-MeOH solution. Cyclic and square wave voltammetry studies showed that the complexes gave three one-electron ligand-based reductions and two one-electron oxidation couples having diffusion controlled mass transfer character. Assignments of these redox couples were confirmed by spectroelectrochemical measurements. The observation of split Q bands, which are characteristic spectral behavior of metal-free phthalocyanines, indicates demetallization of the complexes during the spectroelectrochemical measurement under the applied potentials. The types of the substituents on the ring of the phthalocyanines affect the demetallization process of the complexes.

Full text of DOI:10.1016/j.poly.2010.09.035

Polyhedron 29 (2010) 3394–3404
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, H- or J-type aggregations, electrochemistry and in situ
spectroelectrochemistry of metal ion sensing lead(II) phthalocyanines
b,
Armag˘an Günsel a, Meryem N. Yarasßir a, Mehmet Kandaz a, , Atıf Koca
⇑
⇑
a Department of Chemistry, Sakarya University, 54100 Esentepe, Sakarya, Turkey
b Chemical Engineering Department, Engineering Faculty, Marmara University, 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:
We report, in this study, peripherally 3- and 4-substituted functionalized ionophore ligands (1–3) and
their - and b-tetra polyalcohol substituted lead(II) phthalocyanines M{Pc[S–CH(C3H7)(C2H5OH)]4} (7,
Received 10 May 2010
Accepted 21 September 2010
Available online 7 October 2010
a
9 and 11) and M{Pc[S–C6H12(OH)]4} (8, 10 and 12) which are a mixture of different isomers. The com-
plexes have been fully characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, MS (MALDI-TOF)
and UV–Vis spectral data. These complexes induced H-type (face-to-face fashion) or J-aggregate (edge-
to-edge) dimers when titrated with AgNO3 or Na2PdCl4 in a THF–MeOH solution. Cyclic and square wave
voltammetry studies showed that the complexes gave three one-electron ligand-based reductions and
two one-electron oxidation couples having diffusion controlled mass transfer character. Assignments
of these redox couples were confirmed by spectroelectrochemical measurements. The observation of split
Q bands, which are characteristic spectral behavior of metal-free phthalocyanines, indicates demetalliza-
tion of the complexes during the spectroelectrochemical measurement under the applied potentials. The
types of the substituents on the ring of the phthalocyanines affect the demetallization process of the
complexes.
Keywords:
Phthalocyanine
Metal sensing
Lead
Aggregation
Cyclic voltammetry
Spectroelectrochemistry
Demetallization
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
the PbII ion (1.75 Å) is greater than the radius of the inner core.
Therefore, the PbII ion does not fit inside the core cavity and be-
Phthalocyanines are currently of great technological interest
due to their excellent optical and electronic properties as well
as their chemical and thermal stabilities [1–4]. The spectroscopic
properties of phthalocyanines (Pcs) complexes are influenced
strongly by the metal ion in the cavity or moieties on the
periphery of the phthalocyanines. The metal ion binding capabil-
ity of the Pcs on the periphery, based on molecular design, is
also of great importance in terms of changing the photophysical,
electrochemical and optoelectronic properties, causing higher po-
tential utility [5–7]. The peripheral coordination of MPc with
various metal ions will result in the alteration of the molecular
conformation. Several conformations are known in phthalocya-
nine chemistry [8–10]. Among them, the planar conformation
of Pcs can be distorted by some metal ions, such as PbII, TiIV, SnII,
through conformational stress [11–13]. MPcs metalized with PbII
or SnII metals show a domed conformation [14]. The radius of
comes pushed up at the center core of the phthalocyanine plane
[1]. So, its structure becomes non-planar with a domed confor-
mation, which can give rise to demetallization in a redox reac-
tion [10,15].
Phthalocyanines show, on the other hand, a propensity to
aggregate through coplanar association of the MPc rings in solu-
tion, which may negatively impact their solubility and photochem-
ical properties [16–19]. Peripheral substitutions and some metal
ions in the core are used for enhancing the solubility and changing
the aggregation behavior of MPcs [20]. Also, there has been keen
interest in phthalocyanine derivatives (Pcs) which bear specially
designed peripheral substituents that coordinate with alkaline or
transition metal ions [21–23].
In this study, in order to tune the molecular properties of lea-
d(II) phthalocyanines, different functional groups have been intro-
duced to the peripheral or non-peripheral position of the
precursors. Although a significant number of reports on PbPcs are
already available in the literature, to the best of our knowledge
PbPcs having peripheral functionality have not been investigated
[8–10,13,14,20]. We, therefore, have synthesized, characterized
and examined metal ion sensing, voltammetric and spectroelectro-
chemical properties of lead(II) phthalocyanines.
⇑
Corresponding authors. Tel.: +90 264 2955946; fax: +90 264 2955950 (M.
Kandaz), tel.: +90 216 3480292; fax: +90 216 3480293 (A. Koca).
E-mail addresses: mkandaz@sakarya.edu.tr (M. Kandaz), akoca@marmara.edu.tr
(A. Koca).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.09.035

A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
3395
2.2. Synthesis
2. Experimental
2.2.1. 30-(2,3-Dihydroxypropylthio)-phthalonitrile (1) and 40-(2,3-
2.1. Materials and equipments
dihydroxypropylthio)-phthalonitrile (2)
3-Mercapto-1,2-propanediol (1.25 g, 11.57 mmol) was dis-
solved in 10 cm3 dry DMF and then finely ground anhydrous
K2CO3 (ꢃ2.00 g, excess) was added to this mixture. Then 3-
nitrophthalonitrile or 4-nitrophthalonitrile (2.00 g, 11.56 mmol)
was added to this mixture dropwise at 313 K, stirring effectively
under an N2 atmosphere. The reaction mixture was monitored by
TLC (CHCl3) under the N2 atmosphere at ca. 313 K for 3 day. After
the reaction mixture was cooled to room temperature, it was
poured into ca. 200 cm3 ice-water media. The creamy precipitate
that formed was filtered and then washed with ca. 100 cm3 water
until the washings became neutral. The crude product was dis-
solved in ca. 20 cm3 THF and filtered again. The final product was
chromatographed over a silica gel column using a mixture of CHCl3
and MeOH (5/1) as eluent, giving a hydroscopic oily solid. Finally
the pure powder was dried in vacuo.
Pb(O2Me)2ꢀH2O was purchased from Aldrich. All other reagents
were obtained from Merck and Fluka and used without
purification. 3-Nitrophthalonitrile, 4-nitrophthalonitrile, 40-(1-hy
droxyhexan-3ylthio)-phthalonitrile (4), 30-(6-hydroxyhexylthio)-
phthalonitrile (5) and 40-(6-hydroxyl hexylthio)-phthalonitrile
(6) were prepared according to the literature procedure [18,24–
26]. All reactions were carried out under dry N2 atmosphere.
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. MS spectra were re-
corded in the reflectron mode with an average of 50 shots. An
a
-cyano 4-hydroxycinnamic acid (CHCA, 20 mg mLꢁ1 in THF or
DMF) matrix for all compounds was prepared. 1H NMR and 13C
NMR spectra were recorded on a Bruker 300 spectrometer instru-
ment. Multiplities are given as s (singlet), d doublet), t (triplet).
FT-IR spectra (KBr) were recorded on an ATI UNICOM-Mattson
1000 spectrophotometer. Routine UV–Vis spectra were obtained
in a quartz cuvette on an Agilent Model 8453 diode array spectro-
photometer. Chromatography was performed with silica gel
(Merck grade 60) from Aldrich. The homogeneity of the products
was tested in each step by TLC (SiO2, CHCl3 and MeOH).
Yield of 1: 1.12 g (41.34%); m.p.: 387 K; FT-IR (KBr, m
max/cmꢁ1):
3363, 3226 (CH2CH(R)–OH, CH2–OH), 3067, 2927, 2879 (Aliph-
CH2), 2231 (–CN), 1720, 1705 (w, H–Oꢀ ꢀ ꢀH), 1568 (st), 1454,
1423, 1406, 1352, 1292, 1210, 1197, 1155, 1099, 1068, 1033,
1014, 879, 856, 735; 1H NMR (DMSO-d6) d, ppm: 7.88–7.72 (dd,
t, dd 3H, Ar–H, H4, H5 and H6 (1/1/1)), 5.21 (d, –CHOH), 4.80 (t,
–CH2–OH, D2O exchangeable; shift 5.0 and 5.35), 3.65 (m, –CH),
3.34 (t, 2H, –CH2OH), 3.05 (t, 2H, CH–CH2–S–); 13C NMR (DMSO-
d6) d, ppm: 146.34 (Ar–C–S), 134.40, 132.20, 130.64, 116.53,
116.48, 115.09, 115.07, 112.95, 7069 (–CH2OH), 65.03 (–CH2OH),
40.42 (DMSO), 36.87 (S–CH2); Anal. Calc. for C11H10N2O2S (234 g/
mol): C, 56.40; H, 4.30; N, 11.96; Found: C, 56.14; H, 4.35; N,
11.48%. MS (MALDI-TOF): m/z: 234.3 [M]+, 235.3 [M]+.
Cyclic voltammetry (CV) and square wave voltammetry
(SWV) measurements were carried out with a Gamry Reference
600 potentiostat/galvanostat utilizing a three-electrode configu-
ration at 25 °C. The working electrode was a Pt disc with a sur-
face area of 0.071 cm2. The surface of the working electrode was
polished with a diamond suspension before each run. A Pt wire
served as the counter electrode. A saturated calomel electrode
(SCE) was employed as the reference electrode and was sepa-
rated from the bulk of the solution by a double bridge. Ferrocene
was used as an internal reference. Electrochemical grade tetrabu-
tylammonium perchlorate (TBAP) in extra pure dichloromethane
(DCM) was employed as the supporting electrolyte at a concen-
tration of 0.1 ꢂ 10ꢁ3 mol cmꢁ3. High purity N2 was used for
deoxygenating for at least 15 min prior to each run and to main-
tain a nitrogen blanket during the measurements. Throughout
the process, the reference electrode tip was moved as close as
possible to the working electrode so that the uncompensated
resistance of the solution was a smaller fraction of the total
resistance, and therefore the potential control error was low.
Moreover, IR (current ꢂ resistance) compensation was applied
to the CV and SWV scans to further minimize the potential con-
trol error.
Yield of 2: 1.45 g (53.60%); m.p.: 383 K; FT-IR (KBr, m
max/cmꢁ1):
3336 (br, CH2CH(R)–OH, CH2–OH), 3011, 3059, 2937, 2888 (Aliph-
CH2), 2230 (–C„N), 1737, 1705 (w, H–Oꢀ ꢀ ꢀH), 1565 (st), 1477,
1402, 1388, 1345, 1278, 1220, 1192, 1126, 1097, 1068, 1050,
885, 866, 835; 1H NMR (DMSO-d6) d, ppm: 7.96–7.70 (s, dd, dd,
3H, Ar–H, H2, H5 and H6 (1/1/1)), 5.18 (d, –CHOH), 4.80
(t, –CH2–OH, D2O exchangeable), 3.63 (m, –CH), 3.54 (t, 2H, –
CH2OH), 3.03 (t, 2H, CH–CH2–S–); 13C NMR (DMSO-d6) d, ppm:
148.26 (Ar–C–S), 134.21, 131.01, 130.90, 116.89, 116.43, 115.62,
110.00, 119.99, 70.72 (–CH2OH), 65.09 (–CH2OH), 40.42 (DMSO),
36.74 (S–CH2); Anal. Calc. for C11H10N2O2S (234 g/mol): C, 56.40;
H, 4.30; N, 11.96. Found: C, 56.22; H, 4.28; N, 11.52%. MS (MAL-
DI-TOF): m/z: 234.5 [M]+, 235.3 [M]+.
2.2.2. 30-(1-Hydroxyhexan-3ylthio)-phthalonitrile (3)
In situ spectroelectrochemical measurements were carried out
with an Ocean-optics QE65000 diode array spectrophotometer
equipped with a potentiostat/galvanostat utilizing a three-elec-
trode configuration of a thin-layer quartz spectroelectrochemical
cell at 25 °C. The working electrode was a Pt tulle. A Pt wire coun-
ter electrode separated by a glass bridge and a SCE reference elec-
trode separated from the bulk of the solution by a double bridge
were used. In situ electrocolorimetric measurements, under poten-
tiostatic control, were obtained using an Ocean Optics QE65000
diode array spectrophotometer in the color measurement mode
by utilizing a three-electrode configuration of a thin-layer quartz
spectroelectrochemical cell. The standard illuminant A with a 2°
observer at constant temperature in a light booth designed to ex-
clude 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 MPc. During
the measurements, readings were taken as a function of time un-
der kinetic control.
3-Mercapto-1-hexanol (0.77 g, 5.78 mmol) and 3-nitrophthalo-
nitrile (1.00 g, 5.78 mmol) were dissolved in 10 cm3 dry DMF and
heated at 318 K in an N2 atmosphere for 1 h. Then finely ground
anhydrous K2CO3 (ꢃ1.20 g, 8.67 mmol) was added portionwise to
the solution mixture over 0.5 h. The reaction mixture was stirred
effectively under N2 at 313–318 K for 3 days. After the reaction
mixture was cooled to the room temperature, it was poured into
ca. 150 cm3 ice-water media. The creamy precipitate that formed
was filtered and then washed with water until the washings be-
came neutral. The crude product was dissolved in ca. 30 cm3 CHCl3
and washed again with ca. 50 cm3 5% NaHCO3 to remove any unre-
acted starting compounds. The creamy solution was dried using
anhydrous Na2SO4, and then filtered. The solvent, CHCl3, was re-
moved under reduced pressure, giving a creamy powder. It was
chromatographed in a silica gel column using a mixture of CHCl3
and MeOH (100/5) as the eluent, giving the hydroscopic solid, 30-
(1-hydroxyhexan-3-ylthio)-phthalonitrile (3). Finally the pure
powder was dried in vacuo.

3396
A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
Yield: 1.26 g (83.8%); m.p.: oily; FT-IR (KBr,
m
max/cmꢁ1): 2231
successively with first ca. 50 cm3 hexane, and then ca. 50 cm3
(–CN), 3420, 3246 (CH2–OH), 3054, 3021 (Ar–H), 2928, 2876,
2855 (Aliph-CH2) 1715 (H–Oꢀ ꢀ ꢀH, weak), 1585 (st), 1540, 1476,
1388, 1275, 1199, 1120, 1075, 988, 856, 744, 570; 1H NMR
(DMSO-d6) d, ppm: 7.74 (dd, 1H, ortho to SR, phenyl H5), 7.67 (s,
isomer, 1H, meta to CN and SR, phenyl H5), 7.60 (dd, 1H, ortho
to Ar–H, phenyl H6), 4.58 (s, t, br, –CH2–OH, D2O exchangeable),
3.60 (t, 2H, –CH2OH), 2.62 (–CH(R)–S–), 1.78 (m, 2H, –CH2–CH2
OH), 1.58 (m, 2H, CH2CH2–CH3), 1.35 (m, CH2CH3), 0.96 (t, CH3);
13C NMR (DMSO-d6) d, ppm: 142.1, 134.8, 131.8, 130.4, 116.3,
114.8, 115.9, 115.8, 59.9 (–CH2OH), 40.44 (DMSO), 39.8 (–CH2),
39.3 (CH2CH2OH), 39.5 (CH2CH2CH3), 14.0 (CH3); Anal. Calc. for
CH3CN to remove unreacted impurities. The main compound was
extracted with CH2Cl2. The solvent, CH2Cl2, was removed under re-
duced pressure giving green oily compound. The pure phthalocya-
nines were purified by flash-chromatography using CH2Cl2. Both
compounds are soluble in CH2Cl2, CHCl3, MeOH, EtOH, THF, DMF,
DMSO and pyridine and slightly soluble in CH3CN.
Yield of 9: 0.055 g (30.65%). Anal. Calc. for C56H64N8O4S4Pb
(1246 g/mol): C, 53.93; H, 5.14; N, 8.99. Found: C, 53.33; H, 5.15;
N, 8.78%. FT-IR [KBr
m
max/cmꢁ1]: 3278 (br, H-bonded), 2954,
2927, 2883, 1722 (w, H–Oꢀ ꢀ ꢀH), 1653, 1600, 1525, 1463, 1377,
1315, 1273, 1212, 1092, 1034, 874, 856, 795; 1H NMR (DMSO-
d6): d, ppm 8.12–7.75 (m, 12H, br, phenyl H3, H5, H6), 5.23 (s, t,
br, –CH2–OH, D2O exchangeable), 4.14 (t, br, 8H, –CH2OH), 3.42
(m, br, 4H CH2CH(–S–)CH2), 3.30 (DMSO), 1.80–1.70 (m, 8H,
CH2CH2CH), 1.60–1.45 (q, 8H, CH2CH2CH–), 1.45–1.35 (m, 8H
C
14H16N2OS: C, 64.62; H, 6.15; N, 10.77. Found: C, 64.11; H, 6.12;
N, 10.38%. MS (ESI-MS): m/z (45%): 261.4 [M]+.
2.2.3. 1(4),8(11),15(18),22(25)-Tetrakis-(2,3-dihydroxypropylthio)-
lead(II)phthalocyanine (7); 2(3),9(10),16(17),23(24)-tetrakis
{2,3-dihydroxypropylthio)-lead(II) phthalocyanine (8)
CH2CH2CH3), 0.98 (t, 12H, CH3). UV–Vis (DMF): kmax nm (log
738 ( *), 701 (agg), 668 (n– *), 453 (CT), 339 (deeper,
-cyano 4-hydroxycinnamicacid;
e):
p
–p
p
p–p*);
30-(2,3-Dihydroxypropyl)-phthalonitrile (1) (0.25 g, 1.07 mmol)
or 40-(2,3-dihydroxypropyl)-phthalonitrile (2) (0.25 g, 1.07 mmol)
and anhydrous Pb(O2CMe)2 (0.035 g, 1.07 mmol), in the presence
of 0.5 cm3 N,N-dimethylaminoethanol (NNDMAE) and without
1,8-diazabicyclo [5.4.0] undec-7-ene (DBU, 0.05 cm3) as a strong
base, were heated to reflux temperature in a sealed tube under
an N2 atmosphere for 5 h. The color of the mixture turned green
during 0.5 h heating, and the heating was continued for an addi-
tional 4 h. The green product was then cooled to room tempera-
ture. The crude product was washed several times successively,
first with ca. 30 cm3 i-PrOH, acetone and then with CH3CN to re-
move impurities. The lead(II) phthalocyanines were purified by
flash-chromatography using CHCl3. Finally, they were dried in va-
cuo. While product 7 is soluble in DMF, DMSO and pyridine, com-
pound 8 is slightly soluble in MeOH, THF, and shows excellent
solubility in DMF and DMSO.
MALDI-TOF-MS m/z (as matrix; a
CHCA): 1247 [M+H]+.
Yield of 10: 0.82 g (32.32%). C56H64N8O4S4Pb (1246 g/mol): C,
53.93; H, 5.14; N, 8.99. Found: C, 53.85; H, 5.18; N, 8.88%. FT-IR
[KBr m
max/cmꢁ1]: 3290 (vb), 3065, 2954, 2929, 2870, 1768 (w, H–
Oꢀ ꢀ ꢀH), 1712 (st), 1660 (w), 1598, 1519, 1481, 1454, 1417, 1359,
1313, 1232, 1134, 1066, 1033, 904, 821; 1H NMR (DMSO-d6): d,
ppm 8.07–7.73 (m, br, 12H, phenyl H3, H5, H6), 5.02 (s, t, br, 4H,
–CH2–OH, D2O exchangeable), 3.84 (t, br, 8H, –CH2OH), 3.44 (m,
br, 4H, CH2CH(–S–) CH2), 3.30 (DMSO), 1.79–1.72 (m, 8H,
CH2CH2CH), 1.58–1.47 (q, 8H, CH2CH2CH–), 1.43–1.36 (m, 8H,
CH2CH2CH3), 0.96 (t, 12H, CH3). UV–Vis (THF): kmax nm (log
732 ( *), 696 (agg) 670 (n– *), 413 (CT), 349 (deeper,
-cyano 4-hydroxycinnamicacid;
e):
p–p
p
p–p*);
MALDI-TOF-MS m/z (as matrix;
a
CHCA): 1247 [M+H]+.
Yield of 7: 0.045 g (14.73%); Anal. Calc. for C44H40N8O8S4Pb
(1142 g/mol): C, 46.23; H, 3.50; N, 9.81. Found: C, 46.04; H, 3.57;
N, 9.26%. FT-IR (KBr,
2.2.5. 1(4),8(11),15(18),22(25)-Tetrakis-(6-hydroxyhexylthio)-
phthalocyaninatolead(II) (11) 2(3),9(10),16(17),23(24)-tetrakis-
(6–hydroxyhexylthio)phthalocyaninatolead(II) (12)
m
max/cmꢁ1): 3290, 3240 (br, H-bonded),
3045 (Ar–H), 2966, 2916, 2874, 1715, 1705 (w, H–Oꢀ ꢀ ꢀH), 1651,
1564, 1534, 1398 (st), 1252, 1194, 1102, 1052, 889, 845, 744; 1H
NMR (DMSO-d6) d, ppm: 7.78–7.22 (m, superimposed 12H, phenyl
H4, H5 and H6), 5.20 (d, very broad, 4H, –CH–OH), 4.74 (t, 4H, very
broad, –CH2–OH, D2O exchangeable), 3.68 (m, 4H, –CH), 3.54 (t, 8H,
The same procedures as described for the preparation of 7 and 8
were used to prepare compounds 11 and 12, except the purifica-
tion steps started with
5 and 6 (0.15 g, 0.576 mmol) and
Pb(O2CMe)2 (0.19 g, 0.576 mmol). The crude product was washed
several times successively, with first 20 cm3 hexane, and then
20 cm3 CH3CN to remove impurities. The main compound was ex-
tracted with ca. 50 cm3 CH2Cl2, then the phthalocyanines (11 and
12) were purified by flash-chromatography using CH2Cl2. The sol-
vent, CH2Cl2, was removed under reduced pressure giving green
oily compounds. Both compounds are soluble in CH2Cl2, CHCl3,
MeOH, EtOH, THF, DMF, DMSO and pyridine, and are slightly solu-
ble in CH3CN.
–CH2OH), 2.85 (d, 8H, CH2–CH2–S–); UV–Vis (THF) kmax nm (log
743 ( *), 707 (agg), 687 (n– *), 466 (CT), 341 (deeper,
-cyano 4-hydroxycinnamic acid;
e
):
p–p
p
p–p*);
MALDI-TOF-MS m/z (as matrix;
a
CHCA): 1143.
Yield of 8: 0.051 g (16.69%); Anal. Calc. for C44H40N8O8S4Pb
(1142 g/mol): C, 46.23; H, 3.50; N, 9.81. Found: C, 46.11; H, 3.55;
N, 9.28%. FT-IR (KBr m
max/cmꢁ1): 3290, 3240 (br, H-bonded), 3045
(Ar–H), 2966, 2916, 2874, 1713, 1703 (w, H–Oꢀ ꢀ ꢀH), 1645, 1562,
1531, 1395, 1317, 1232, 1184, 1161, 889, 869, 812, 794; 1H NMR
(DMSO-d6) d, ppm: 7.75–6.95 (m, superimposed 12H, phenyl H4,
H5 and H6), 5.15 (d, very broad, 4H, –CH–OH), 4.63 (t, 4H, very
broad, –CH2–OH, D2O exchangeable), 3.65 (m, 4H, –CH), 3.55 (t,
8H, –CH2OH), 2.80 (d, 8H, CH2–CH2–S–); UV–Vis (THF) kmax nm
Yield of 11: 0.055 g (30.65%); Anal. Calc. for C56H64N8O4S4Pb
(1246 g/mol): C, 53.93; H, 5.14; N, 8.99. Found: C, 53.33; H, 5.15;
N, 8.78%. FT-IR (KBr
m
max/cmꢁ1): 3278 (br, H-bonded), 2954,
2927, 2883, 1722 (w, H–Oꢀ ꢀ ꢀH), 1653, 1600, 1525, 1463, 1377,
1315, 1273, 1212, 1092, 1034, 874, 856, 795; 1H NMR (DMSO-d6)
d, ppm: 7.85–7.60 (m, 12H, phenyl H4, H5 and H6), 4.20 (t, br,
4H, –CH2–OH, D2O exchangeable), 3.58 (t, 8H, –CH2OH), 2.92 (8H,
CH2–CH2–S–), 1.68 (m, 8H, –CH2CH2–S–Ar), 1.50 (m, 8H,
CH2CH2CH2–OH), 1.37 (m, 16 H, 2ꢂCH2CH2CH2OH). UV–Vis
(log
e
): 724 (
*); MALDI-TOF-MS m/z (as matrix;
namic acid; CHCA): 1144.3 [M+H]+.
p
–
p
*), 690 (agg), 655 (n–
p
*), 404 (CT), 354 (deeper,
p–p
a
-cyano 4-hydroxycin-
(DMF) kmax nm (log
(CT), 340 (deeper,
4-hydroxycinnamic acid; CHCA): 1248.1 [M+H]+.
e
): 757 ( *), 457
p
–
p
*), 702 (agg), 680 (n–
p
2.2.4. 1(4),8(11),15(18),22(25)-Tetrakis-(1-hydroxyhexan-3-
ylthio)phthalocyaninatolead(II) (9) 2(3),9(10),16(17),23(24)-tetrakis-
(1-hydroxyhexan-3-ylthio)phthalocyaninatolead(II) (10)
p–
p*); MALDI-TOF-MS m/z (as matrix; a-cyano
Yield of 12: 0.82 g (32.32%); C56H64N8O4S4Pb (1246 g/mol): C,
The same procedure as described for the preparation of 7 and 8,
were used to prepare compounds 9 and 10, except the purification
steps started with 3 (0.15 g, 0.576 mmol) and Pb(O2CMe)2 (0.19 g,
0.576 mmol). The crude product was washed several times
53.93; H, 5.14; N, 8.99. Found: C, 53.85; H, 5.18; N, 8.88%. FT-IR
(KBr m
max/cmꢁ1): 3290 (vb), 3065, 2954, 2929, 2870, 1768 (w, H–
Oꢀ ꢀ ꢀH), 1712 (st), 1660 (w), 1598, 1519, 1481, 1454, 1417, 1359,
1313, 1232, 1134, 1066, 1033, 904, 821; 1H NMR (DMSO-d6) d,

A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
3397
Scheme 1. Synthetic route of 30-(2,3-dihydroxypropylthio)-phthalonitrile (1); 40-(2,3-dihydroxypropylthio)-phthalonitrile (2), 30-(1-hydroxyhexan-3ylthio)-phthalonitrile
(3) and their
- and b-lead(II)phthalocyanines{M[Pc(S–CH3CH2(OH)CH2(OH))]4} (M = PbII (7–12). (i) K2CO3, 3-mercapto-1,2-propanediol, DMF, 303 K, 3 days; 3-mercapto-1-
hexanol, DMF, 303 K, 3 days for 3; (ii) anhydrous Pb(acac)2, NNDMEA.
a
Fig. 1. (a) Simulated and (b) experimental isotopic patterns of the MALDI-TOF spectrum of complex 7.

3398
A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
ppm: 7.80–7.55 (br, 12H, phenyl H3, H5 and H6), 4.18 (s, t, br,
–CH2–OH, D2O exchangeable), 3.58 (t, 12H, –CH2OH), 2.96 (CH2–
S–), 1.62 (m, 2H, CH2–S–Ar), 1.45 (m, 2H, CH2CH2CH2–OH), 1.37
the core of all PbPcs. The demetallization process occurs because
the metal ion does not fit inside the central cavity and becomes
pushed up above the Pc plane.
(m, 2ꢂCH2–CH2CH2). UV–Vis (THF) kmax nm (log
688 (agg), 664 (n– *), 412 (CT), 349 (deeper,
-cyano 4-hydroxycinnamic acid; CHCA):
e
): 734 (
p–p*),
p
p–p*); MALDI-TOF-
3.2. Spectroscopic characterization
MS m/z (as matrix;
a
1248.4 [M+H]+.
Lead(II) phthalocyanine complexes 7–12 were characterized by
FT-IR, UV–Vis, MALDI-TOF and 1H NMR spectroscopy, as well as by
3. Results and discussion
3.1. Synthesis and characterization
The
a
and b tetra substituted functional lead phthalocyanines,
and 11) and M{Pc[S–
M{Pc[S–CH (C3H7)(C2H5OH)]4} (7,
9
C6H12(OH)]4} (8, 10 and 12), as a mixture of different isomers, have
been synthesized by the cyclotetramerization of the corresponding
phthalonitriles carrying 30-(2,3-dihydroxypropyl) (1), 40-(2,3-
dihydroxypropyl) (2), 30-(1-hydroxyhexan-3ylthio) (3), 40-(1-
hydroxyhexan-3ylthio) (4) [25], 40-(6-hydroxyhexylthio) (6) [21]
and 30-(6-hydroxyhexylthio) (5) [26] functional moieties in the
presence of anhydrous Pb(O2CMe)2 and NNDMAE solvent
(Scheme 1). The phthalocyanines were purified by flash-chroma-
tography using CHCl3 and CH2Cl2. The functional substituents
and pyramidal geometry of the lead(II) complexes (7–12) confer
better solubility than expected in a number of organic solvents,
including CHCl3, CH2Cl2, THF, EtOH, DMF, DMSO and DMAA. The
purification steps were tedious owing to the functional substitu-
ents on the periphery of the Pcs and possible demetallization at
Fig. 3. UV–Vis spectra of 11 in THF/MeOH during titration with PdII (in MeOH).
Fig. 4. UV–Vis spectra of 12 in THF/MeOH during titration with (a) PdII (in MeOH)
Fig. 2. UV–Vis spectra of (a) 8 and (b) 10 in THF/MeOH during titration with AgI (in
MeOH).
and (b) AgI (in MeOH).

A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
3399
elemental analysis. In the FT-IR spectra of the complexes, the most
pronounced bands were the diagnostic –OH absorptions between
3400 and 3200 cmꢁ1, antisymmetric C–H stretching vibrations of
CH2 and CH3 between 2975 and 2850 cmꢁ1 and S–CH2 stretching
at ca. 1220–1240 cmꢁ1 [10,13,18]. The most significant indicators
for the formation of PbIIPc complexes 7–12 are the disappearance
of the deuterium exchangeable signals belonging to peripheral –
OH protons in the middle of the 1H NMR spectra (d = 5.5–
4.5 ppm) [18,25]. The shifts and changes in intensity of certain
peaks in the 1H NMR spectra of 7–12 are consistent with the pre-
cursors. The electronic spectra of PbIIPcs 7–12 were recorded in
DMF solvent in the range 300–900 nm. UV–Vis spectral measure-
ments indicated that the Q-band assigned to the * transitions
for all the PbPcs is particularly sensitive to the presence of both
substituents on the benzene ring and the metal atom in phthalocy-
anine core [10,15,27]. The B-bands of the complexes, assigned to
p–p
the deeper
p–p* transitions, were observed between 330 and
370 nm. Incorporation of the electron acceptor PbII ion in the core
of the Pc molecule caused a bathochromic shift of the Q band to a
pronounced extent in comparison to the ones observed in the spec-
tra of H2Pc and H2Pz [10,13,15]. The isotopic mass distribution of
the protonated molecular ion peak of complex 7 (Fig. 1) and 8 were
Table 1
Voltammetric data of the lead(II) phthalocyanines.
Complex
Redox processes
Oxidation 2
dDE1/2
Oxidation 1
Reduction 1
Reduction 2
Reduction 3
Reduction 4
8
E1/2 (V vs. SCE)
Ep (mV)
Ipa/Ipc
0.72
65
ꢁ0.66
62
0.91
ꢁ0.67
172
0.73
ꢁ0.63
60
0.45
ꢁ0.64
55
ꢁ0.90
68
0.78
ꢁ1.01
197
0.85
ꢁ0.94
75
0.85
ꢁ0.94
57
ꢁ1.43
1.38
1.48
1.35
1.38
D
0.80
0.81
140
0.66
0.72
100
0.55
0.75
80
10
11
12
E1/2 (V vs. SCE)
ꢁ1.34
ꢁ1.83e
ꢁ1.82e
ꢁ1.86e
D
Ep (mV)
Ipa/Ipc
aE1/2 (V vs. SCE)
bDEp (mV)
cIpa/Ipc
ꢁ1.50
100
0.92
ꢁ1.25
130
E1/2 (V vs. SCE)
1.09e
D
Ep (mV)
Ipa/Ipc
0.75
0.90
0.85
0.72
a
b
c
E1/2 = (Epa + Epc)/2 at 100 mV sꢁ1 (Epc for reduction, Epa for oxidation for irreversible processes).
Ep = Epa ꢁ Epc at 0.100 Vsꢁ1 scan rate.
Ipa/Ipc for reduction, Ipc/Ipa for oxidation processes at 0.100 Vsꢁ1 scan rate.
E1/2 = E1/2 (first oxidation) ꢁ E1/2 (first reduction).
d
e
Recorded by SWV.
Fig. 5. (a) CVs of 11 (5.0 ꢂ 10ꢁ7 mol cmꢁ3) at various scan rates on Pt in DCM/TBAP (inset SWV of 11; SWV parameters: pulse size = 100 mV; frequency: 25 Hz) (b) CVs of 11
recorded with different switching potentials at 0.100 Vsꢁ1 scan rate (inset: repetitive CVs of the first reduction process of 11).

3400
A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
observed between 1143 and 1149 Da, with 1 Da mass increments.
Complexes 9 and 10 gave isotopic mass distributions of the proton-
ated molecular ion peak between 1247 and 1253 Da with 1 Da
mass increments.
concentration of the metal salt (ca. 10ꢁ6 mol cmꢁ3) was kept high-
er than those of the MPc (ca. 10ꢁ8 mol cmꢁ3) to diminish the
absorption decreases of the bands due to dilution. Gradual addition
of AgI to the solutions of 7–12 at room temperature caused a grad-
ual color change, from green to light-green, which suggests that
the complexes coordinate with AgI to form aggregated species.
Interaction of AgI with these complexes decreases the solubility
of the complexes formed, which results in the observation of an
intractable product at the end of the titration. As shown in
Fig. 2a and b (8 and 10) and Fig. 4b (11), AgI binding to the donor
atoms of the complexes results in pronounced effects on the Q, B
3.3. Metal ion binding titrations
Generally, Pc compounds tend to interact with each other by
attractive
face, leading to aggregation [16–19,25,26]. The aggregation of
Pb[Pc( -SR)4] and Pb[Pc(b-SR)4] (R: functional group) complexes
p–p* stacking due to their extended flat aromatic sur-
a
and shoulder band absorptions (n–
the non-bonding sulfur electron (n) to the
p
* transitions: attributed to
* phthalocyanine orbi-
were detected using UV–Vis spectroscopy (Fig. 1). The shape of
the Q-band is known to be a sensitive probe in determining the
types of Pc aggregation. Blue-shifting, broadening and a decrease
of the Q-band in intensity, and formation of the Q-band of the
MPc dimer in the higher energy region are indicative of face-
to-face conformations [16–19].
It is well known that sulfur atoms on the periphery of the
metallo or metal-free phthalocyanine complexes (MPcs) are opti-
cally sensitive to soft metal ions, such as AgI and PdII. Therefore,
we have employed UV–Vis spectroscopy to monitor the metal-
ion binding capability of the MPc. Each titration experiment was
carried out using a MeOH/thf solution of the MPcs (10/90, v/v) to
ensure complete dissolution of the analyte salt in MeOH. The
p
tal) [16–19,27]. While AgI is added gradually to 7–12, the Q band
absorption intensities of the monomeric species (743, 724, 738,
732, 757, 734 nm respectively) decrease gradually and the band
intensities assigned to the dimer aggregated species (at 693, 690,
694, 693, 740 and 687 nm respectively) are enhanced simulta-
neously. The B-bands of the complexes shift at the same time to
the higher energy side by about 15–25 nm with a slight change
in intensity. As shown in Figs. 2–4, the spectral changes during
the titrations of the complexes with AgI and PdII give clear isos-
bestic points which demonstrate that the titrations give one type
of aggregated species. This type may a mixture of different isomers,
however these different isomers do not affect the spectral changes
of the proposed aggregated species. The relation between the
absorbance band molar extinction coefficients of the monomeric
and aggregated species indicate dimer formation of the aggregated
species [28,29]. While blue shifts of the Q bands are observed dur-
ing the titration with AgI, the Q bands of the non-peripherally
substituted phthalocyanines (7, 9 and 11) shift to longer wave-
lengths during titration with PdII. These different spectroscopic
changes indicate different types of aggregates (H- and J-types)
and the existence of PdII coordination to the sulfur donor atoms
of the complexes with a square-planar type of formation. This
means that the complexation of the a- or b-substituted complexes
with PdII decreases the concentration of the monomeric units to
some degree, but do not increase the dimeric band to the same ex-
tent due to the formation of slightly less soluble aggregated units.
Consequently, the interaction of the PdII ion with the peripheral
moieties of the complexes causes decomposition of the aggregates
of the planar phthalocyanine molecules to some degree in solution.
As known, spectral shifts due to chromophoric packing can gener-
ally be explained by the molecular exciton model proposed by
Kandaz and co-workers [18,25] which suggests that the
Fig. 6. (a) CVs of 12 (5.0 ꢂ 10ꢁ7 mol cmꢁ3) at various scan rates on Pt in DCM/TBAP.
(b) CVs of 12 recorded with different switching potentials during positive potential
scan at 0.100 Vsꢁ1 scan rate. (c) SWV of 12 recorded with different initial potentials;
SWV parameters: pulse size = 100 mV; frequency: 25 Hz.
Fig. 7. (A) Cyclic voltammograms of
8
(5.0 ꢂ 10ꢁ7 mol cmꢁ3
) with different
switching potentials at 0.100 Vsꢁ1 scan rate on Pt in DCM/TBAP (inset SWV of 8;
SWV parameters: pulse size = 100 mV; frequency: 25 Hz).

A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
3401
bathochromic and hypsochromic shifts correspond to edge-to-
edge (J-aggregates) and face-to-face (H-aggregates) aggregations
Fig. 5 shows the CV and SWV of 11 in the DCM/TBAP electrolyte
system. Complex 11 gives four reduction processes at ꢁ0.63,
ꢁ0.94, ꢁ1.50 and ꢁ1.82 V and one oxidation processes at 0.72 V
versus SCE at 0.100 Vsꢁ1 scan rate. The assignments of the redox
couples are proposed below using spectroelectrochemistry mea-
respectively. When the angle
54.7° < < 90°, the aggregate is defined as the H-aggregate, from
which a blue-shifted absorption with broadening could be de-
tected. However, when is a close to the critical angle, i.e.,
ꢄ 54.7°, the absorption maximum remains almost unshifted or
a
lies within the range
a
a
surements. The anodic to cathodic peak separations (
from 60 to 120 mV with a change in the scan rate from 10 to
500 mV sꢁ1
Ep changing from 60 to 110 mV was obtained for
DEp) changed
a
is bathochromically shifted with broadening when the 3-substi-
tuted phthalocyanines interact with PdII [25]. These uncommon
changes may result from the formation of a PdII–Pc complex exhib-
iting a different geometry, the decomposition of the aggregates and
the formation of square planar type complexes [16–19]. The results
of the titration with AgI or PdII ions are in harmony with those ob-
tained in previous works [16–19,25,26,30].
(D
the ferrocene reference), indicating the reversible electron transfer
character of the complex (Fig. 5a). Reversibility is also illustrated
by the similarity in the forward and reverse SWV scans (Fig. 5a in-
set). However, while the Ipa/Ipc values of the couples are less than
unity at slow scan rates, the values of Ipa/Ipc increases towards
unity with increasing scan rates, suggesting the existence of an
irreversible chemical reaction succeeding the first reduction and
oxidation processes [34]. This kind of chemical reaction might be
the demetallization of the complex assigned by spectroelectro-
chemical measurements, given below. A change of the peak charac-
ter with different switching potentials supports the existence of
this chemical reaction (Fig. 5b). Repetitive cycles between 0 and
ꢁ0.80 V cause a change from reversible to irreversible behavior
for the first reduction process (inset in Fig. 5b). These behaviors
indicate demetallization of the complex after the first reduction
process. Changing from reversible to irreversible character and
the observation of a new wave at 0.37 V indicate that the complex
was also demetallized after the first oxidation process when the
vertex potential goes to more positive potentials, step by step.
Fig. 6 shows the CV and SWV of 12 in the DCM/TBAP electrolyte
3.4. Electrochemical measurements
The solution redox properties of the complexes were studied
using CV and SWV techniques in DCM on a platinum electrode.
Table 1 lists the assignments of the couples recorded and the esti-
mated electrochemical parameters, which included the half-wave
peak potentials (E1/2), the ratio of anodic to cathodic peak currents
(Ipa/Ipc), peak potential separations (
DEp) and HOMO–LUMO gaps
(D
E1/2). The CV and SWV studies reveal that all the complexes give
three well-defined ring-based reductions and two oxidation cou-
ples. The separation between the first and second ring reductions
was found to be in the range 0.33–0.40 V for all the complexes.
These peak separations and the HOMO–LUMO gap values are in
agreement with the reported separation for redox processes in lea-
d(II) phthalocyanine complexes [10,31–35].
system. Changing the substituents from the
a position to the b
position affects the CV and SWV responses of the complex
Fig. 8. In situ UV–Vis spectral changes of 11. (a) (inset: at the beginning of the first reduction process during the potential application at Eapp = ꢁ0.75 V.) Second part of the
spectral changes during the potential application at Eapp = ꢁ0.75 V. (b) The spectral changes during the potential application at Eapp = ꢁ1.05 V (the second reduction process).
(c) The spectral changes during the potential application at Eapp = 0.85 V (the first oxidation process). (d) Chromaticity diagram of 11 (each symbol represents the color of the
electro-generated species; h: neutral 11 PbIIPcꢁ2, s: color of the solution after the first reduction, 4: color of the solution after the second reduction, : color of the solution
after the first oxidation).

3402
A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
considerably. For complex 12, four reduction and two oxidation
processes are recorded at ꢁ0.64, ꢁ0.94, ꢁ1.25, ꢁ1.86, 0.75 and
1.09 V versus SCE at 0.100 Vsꢁ1 scan rate. While the peak character
of complex 11 is affected by the scan rates, switching potentials
and repetitive potential scans, complex 12 is not considerably af-
fected by these stresses. The anodic to cathodic peak separations
a metal free phthalocyanine [10,31,35]. The green color of the solu-
tion (point h x = 0.3249, y = 0.4492) changes to greenish yellow
(point s x = 0.3358, y = 0.409) during the process (Fig. 8d). Further
potential application at ꢁ1.05 V (Fig. 8b) causes a decrease in
(DEp) indicate reversible character of the electron transfer reac-
tions for the reduction processes. The values of Ipa/Ipc for the reduc-
tion couples are unity for the first and second reductions and ca.
0.60 for the third reduction at all scan rates (Fig. 6a). The peak
characters of the reduction processes do not change with the dif-
ferent switching potentials and repetitive CV cycles. However,
the oxidation behavior of the complex changes with the different
switching potentials, as shown in the CV and SWV in Fig. 6b and
c. When the potential is switched before the second oxidation pro-
cess, the complex gives
a quasi-reversible oxidation process
(D
Ep = 130 mV and Ipa/Ipc = 0.80), whereas when the potential is
switched after the second oxidation process, the first quasi-revers-
ible oxidation process becomes irreversible and a new couple is ob-
served at 0.26 V. This new peak shifts to 0.35 V when the potential
was switched from more positive potentials. These behaviors indi-
cate the existence of a chemical reaction after the first oxidation
reaction, which may be demetallization of the complex.
Complex 10 showed very similar CV and SWV responses to 12,
with a small potential shift due to the different electron releasing
ability of the substituents. However, complex 8 gave completely
different CV and SWV responses to the other complexes. It gives
two common ring reduction processes and a very intense uncom-
mon peak at ꢁ1.20 V, which may be due to dinitrile benzene
groups of the products formed after decomposition. This means
that the complex is stable during first two reduction processes,
but decomposes immediately after the second reduction process.
It does not demetallize during the oxidation process, and so gives
a clear reversible oxidation process (Fig 7).
3.5. In situ spectroelectrochemical and in situ electrocolorimetric
measurements
Spectroelectrochemical studies were employed to confirm the
assignments of the redox couples recorded in the CVs and SWVs
of the complexes. The spectroelectrochemical studies indicate dif-
ferent spectroscopic changes to the common ring based redox pro-
cesses because of the demetallization of the complexes.
Demetallization of the PbIIPc complexes was also observed by Kan-
daz et al. [30] during the potential application at just negative of
the first reduction process over a period of a few minutes. In our
previous studies [13,31,35] we also indicated the demetallization
of the PbPcs before or after the first reduction processes and during
the positive potential scans, depending on the substituents. Simi-
larly in this study, demetallization of complexes (10–12) is ob-
served simultaneously with or just after the first reduction and/
or first oxidation of the phthalocyanine rings. In contrast, complex
8 is stable until the second reduction potential and the during oxi-
dation process.
Fig. 8 shows the in situ UV–Vis spectral changes and color
changes of 11 under the applied potential of the redox processes.
During the controlled potential reduction of the complex at
ꢁ0.75 V, two distinct spectral changes are recorded at the same po-
tential application continuously (Fig 8a). At the beginning of the
process, a new band is enhanced at 668 nm while the remaining
spectrum does not change considerably (inset in Fig 8a). These
changes give a split Q band, which indicates the formation of the
metal free phthalocyanine (H2Pc). Then the Q-band at 732 nm, n–
Fig. 9. In situ UV–Vis spectral changes of 12. (a) (inset: at the beginning of the first
reduction process during the potential application at Eapp = ꢁ0.80 V.) Second part of
the spectral changes during the potential application at Eapp = ꢁ0.80 V. (b) The
spectral changes during the potential application at Eapp = 0.90 V (the first oxidation
process). (c) Chromaticity diagram of 12 (each symbol represents the color of the
electro-generated species; h: neutral 12, PbIIPcꢁ2, s: color of the solution after the
p* transition band at 622 nm and the B bands at 346 and 405 nm
decrease in intensity, while the band at 668 nm remains un-
changed. These changes are typical for a ring-based reduction for
first reduction, 4: color of the solution after the second reduction,
: color of the
solution after the first oxidation).

A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
3403
intensity of all the bands, which confirms the decomposition of the
species due to demetallization. The demetallization and then the
decomposition of the complex were also confirmed by the spectral
changes during the re-oxidation of the complex at this stage. Re-
oxidation of the complex at this stage does not result in the regen-
eration of the starting spectrum and color, which indicates that the
second reduction process of the complex is irreversible in that
applying 0.00 V did not result in the regeneration of the starting
spectrum and color. Fig. 8c shows the spectral changes during
the ring-based oxidation process under the applied potential at
0.85 V. During this process, while the absorption of the Q-band at
(Fig. 9a) corresponding to the formation of [H2Pc(ꢁ2)]. Then, at the
same potential application, one of the split Q bands decreases with
a blue shift while the other one remains unchanged, then both
bands decreases in intensity. This final process shows the reduc-
tion of the [H2Pc(ꢁ2)] species to [H2Pc(ꢁ3)], followed by the
decomposition of the reduced species. As shown in Fig. 9b, the ring
oxidation process occurs at 0.90 V potential application, then the
oxidized species are demetallized and then decompose during
the potential application at 1.30 V. Decomposition of the complex
after the demetallization process also explains the CV behavior of
the complex at higher concentrations. The waves recorded at
0.26 V in the CV of the complex may result from the species pro-
duced by the decomposition reaction. Complex 10 gave very simi-
lar spectroscopic changes to 12. The only difference is the ease of
the demetallization process. During the potential application at
ꢁ0.80 V, the Q-band of complex 10 splits into two bands assigned
to the formation of the metal free phthalocyanine. However in the
case of 12, the complex starts to reduce and then demetallized.
Complex 10 was demetallized at the beginning of the potential
application at ꢁ0.80 V, while 12 shows spectroscopic changes cor-
responding to simultaneous ring reduction and demetallization
processes.
732 nm and the n–p* transition band at 622 nm decrease in inten-
sity, new bands are observed at 552 and 890 nm which are as-
signed to a LMCT transition. At the same time, the B band at
415 nm decreases in intensity. The decrease in the Q band without
shift and the observation of new bands at 552 and 890 nm are
characteristic of ring-based oxidation processes. The green color
of the solution changes to orange (point
x = 0.3676, y = 0.3821)
during this process. After this point, when a more positive poten-
tial was applied, all the bands in the spectra decrease in intensity
due to decomposition of the complex.
Complexes 12 (Fig. 9) and 10 give very similar in situ UV–Vis
spectroscopic changes during the potential applications corre-
sponding to the relevant electron transfer processes. In situ UV–
Vis spectroscopic changes of 12 during the potential application
at ꢁ0.80 V (Fig. 9) show that the complex is demetallized during
the first reduction process. At the beginning of the potential appli-
cation at ꢁ0.80 V, a new band starts to appear at 677 nm, while the
intensity of the Q-band at 717 nm does not change due to the
demetallization of the complex. The process result in a split Q band
Complex 8 gives completely different spectroscopic changes to
the other complexes. As shown in Fig. 10, during the potential
applications at ꢁ0.80 and ꢁ1.05 V, the spectral changes indicate
a ligand-based reduction of the complex. A decrease of the Q band
and the observation of a new band at around 600 nm indicate the
ligand-based reduction and are easily assigned to the [PbIIPcꢁ2]/
[PbIIPcꢁ3 ꢁ
the Q band decreases without shift and new bands are observed
]
process (Fig. 10a). At ꢁ1.05 V potential application,
Fig. 10. In situ UV–Vis spectral changes of 8. (a) The spectral changes during the potential application at Eapp = ꢁ0.80 V. (b) The spectral changes during the potential
application at Eapp = ꢁ1.05 V. (c) The spectral changes during the potential application at Eapp = 0.85 V. (d) Chromaticity diagram of 8 (each symbol represents the color of the
electro-generated species; h: neutral 8, PbIIPcꢁ2, s: color of the solution after the first reduction, 4: color of the solution after the second reduction, : color of the solution
after the first oxidation).

3404
A. Günsel et al. / Polyhedron 29 (2010) 3394–3404
at 547 and 640 nm. These spectroscopic changes are indicators of
the [PbIIPcꢁ3]ꢁ/[PbIIPcꢁ4 2ꢁ
redox process (Fig. 10b). After the sec-
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tial of ꢁ1.60 V. As shown in Fig. 10c, the ring oxidation process
occurs at 0.85 V potential application and then the complex
decomposed during the potential application at 1.30 V. Color
changes of the complex during the electron transfer reactions are
monitored by in situ electrocolorimetric measurements and a chro-
maticity diagram of the colors is given in Fig. 10d.
The CV, SWV and in situ spectroscopic responses of the com-
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the positions of the substituents affect the voltammetric and spec-
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with the environment of the phthalocyanine ring. The order of
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the first time. It has been shown that the hetero atoms on the
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puffed up above the Pc plane. Oxidation and reduction of the com-
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Acknowledgements
This work was supported by the Research Fund of TUBITAK
[35] A. Koca, Sß. Bayar, H.A. Dinçer, E. Gonca, Electrochim. Acta 54 (2009) 2684.
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(Project No: TÜBITAK–TBAG 108T094; TÜBITAK–MAG, 106M286).