Highly soluble tetra lauryl alcohol substituted phthalocyanines; Synthesis, electrochemistry, spectroelectrochemistry

Article abstract of DOI:10.1080/00958972.2014.986472

The tetra peripherally β-suted 2(3),9(10),16(17),23(24)-tetrakis undecyloxy phthalocyanine derivatives, M{Pc[O-(CH₂)₁₁CH₃)]₄} Pc: Phthalocyanine, [M: Zn(II)(2), Ga(III)(3), and Ti(IV)(4)], have been synthesized

Full text of DOI:10.1080/00958972.2014.986472

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Highly soluble tetra lauryl alcohol
substituted phthalocyanines;
synthesis, electrochemistry,
spectroelectrochemistry
Ahmet T. Bilgiçlia, M. Nilüfer Yaraşira, Mehmet Kandaza & Atif
Kocab
a Department of Chemistry, Sakarya University, Esentepe, Turkey
b Faculty of Engineering, Department of Chemical Engineering,
Marmara University, Istanbul, Turkey
Accepted author version posted online: 17 Nov 2014.Published
online: 16 Dec 2014.
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To cite this article: Ahmet T. Bilgiçli, M. Nilüfer Yaraşir, Mehmet Kandaz & Atif Koca (2015)
Highly soluble tetra lauryl alcohol substituted phthalocyanines; synthesis, electrochemistry,
spectroelectrochemistry, Journal of Coordination Chemistry, 68:2, 350-366, DOI:
10.1080/00958972.2014.986472
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Journal of Coordination Chemistry, 2015
Vol. 68, No. 2, 350–366, http://dx.doi.org/10.1080/00958972.2014.986472
Highly soluble tetra lauryl alcohol substituted
phthalocyanines; synthesis, electrochemistry,
spectroelectrochemistry
AHMET T. BILGIÇLI†, M. NILÜFER YARAŞIR†, MEHMET KANDAZ*† and
ATIF KOCA‡
†Department of Chemistry, Sakarya University, Esentepe, Turkey
‡Faculty of Engineering, Department of Chemical Engineering, Marmara University, Istanbul, Turkey
(Received 22 July 2014; accepted 17 October 2014)
The tetra peripherally β-substituted 2(3),9(10),16(17),23(24)-tetrakis undecyloxy phthalocyanine
derivatives, M{Pc[O-(CH2)11CH3)]4} Pc: Phthalocyanine, [M: Zn(II)(2), Ga(III)(3), and Ti(IV)(4)],
have been synthesized and characterized using FT-IR, 1H, and 13CNMR, MS (MALDI-TOF), UV–
vis, atomic force microscopy, electro and spectroelectro chemical and elemental analysis. The new
synthesized complexes are soluble in both polar solvents and nonpolar solvents, such as THF, DMF,
CHCl3, CH2Cl2, benzene, and even hexane. Electrochemical and spectroelectrochemical measure-
ments give common metal-based and/or Pc ring-based redox processes which support the proposed
structures of the complexes. While titanium phthalocyanine exhibits metal- and Pc ring-based reduc-
tion and/or oxidation couples, gallium and zinc phthalocyanines give only Pc ring-based electron
transfer processes.
Keywords: Phthalocyanine; Zinc; Gallium and Titanium; Synthesis; Spectroelectrochemistry;
Electrocolorimetry
*Corresponding author. Email: mkandaz@sakarya.edu.tr
© 2014 Taylor & Francis

Lauryl alcohol phthalocyanines
351
1. Introduction
Efforts in the development of new types of highly soluble metallophthalocyanine (MPcs)
complexes have been increasing due to their applications in chemical sensors [1], liquid
crystals [2, 3], photodynamic therapy [4, 5], data storage [6], and non-linear optics [7].
The high-tech capabilities of Pcs materials depend not only on the molecular composition
including the metal center and the number, position, and nature of the substituents, but also
on the molecular architecture [8]. For example, the molecular arrangement (balance between
hydrophobic and hydrophilic properties) in the core and on the periphery is a determining
factor controlling many of the physical properties of the macrocycles including the electrical
photoconductivity, magnetic susceptibility, and optical non-linearity [9]. By functionalizing
the phthalocyanine ring with long aliphatic chains, the solubility increases and liquid crys-
talline compounds can be obtained. Phthalocyanines substituted with hydrophilic aliphatic
alcohol, aliphatic thioalcohol, or polyaliphatic alcohol chains increase solubility in polar
solvents, such as MeOH, EtOH, i-PrOH, THF, CH3CN, and even in water [10–13]. More-
over, introduction of adequate functional/non-functional substituents on the periphery and
non-peripheral positions of the phthalocyanine ring not only improves their solubility by
causing substantial disruption of the strong interaction of the parent phthalocyanine rings
but also increases their applications [14, 15]. For example, the PDT properties of the phtha-
locyanine dyes are strongly influenced by the presence and nature of the central metal ion
and substituents. Also, the presence of electron-donating/electron-withdrawing substituents
is a useful way of regulating the wavelength of the Q band to longer or short wavelengths
[12–14]. Functional phthalocyanines are of particular chemical interest because of their ten-
dency to aggregate in self-assemblies, optical and electrochemical responses to specific ana-
lytes, and capable of binding multiple metal ions for the development of new molecules/
macrocycles [12, 15, 16]. In such systems, the metal in the central macrocyclic cavity and
periphery can be chosen independently, thus giving physical properties not seen in the
phthalocyanine or metal fragment alone [17].
In this article, a new ligand, 4-(undecyloxy)-phthalonitrile, and its tetrasubstituted metall-
ophthalocyanines, M{Pc[O-(CH2)11CH3)]4} [M = Zn(II), Ga(III), and Ti(IV)], are
described. Also in this study, we have performed voltammetric and in situ spectroelectro-
chemical characterization of the newly synthesized MPc complexes.
2. Experimental
Chloroform (CHCl3), tetrahydrofuran (THF), 4-nitrophthalonitrile, 1-dodecanol, tetrabutyl
ammoniumtetrafluoroborate (TBATBF4), Zn(OAc)2, GaCl3, and titanium(IV) butoxide (Ti
(OBu)4) were purchased from Merck and Alfa Aesar and used as received. All other
reagents were obtained from Fluka, Aldrich and Alfa Aesar Chemical Co. and used without
purification. The purity of the products was tested in each step by TLC (SiO2, CHCl3/
MeOH, and THF/MeOH). FT-IR spectra were recorded on a Perkin–Elmer FT-IR spectro-
photometer where samples were dispersed in KBr. Chromatography was performed with sil-
ica gel (Merck grade 60 and Sephadex) from Aldrich. Elemental analyses (C, H, and N)
were performed at the Instrumental Analysis Laboratory of Marmara University. Time-
resolved UV–vis spectra were recorded on an Agilent model 8453 diode array spectropho-
1
tometer. HNMR and 13CNMR spectra were recorded on a Bruker 300 spectrometer. Mass

352
A.T. Bilgiçli et al.
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. Spectra were
recorded in reflectron mode with average of 50 shots. 2,5-Dihydroxybenzoic acid (DHB)
(20 mg mL−1 in THF) matrix for 1, 2, 3, and 4 was prepared. MALDI samples were pre-
pared by mixing complex (2 mg mL−1 in THF) with the matrix solution (1 : 10 v/v) in a
0.5 mL Eppendorf® micro tube. Finally, 1 μL of this mixture was deposited on the sample
plate, dried at room temperature, and then analyzed. Photo-irradiations were measured using
a General Electric quartz line lamp (300 W). A 600 nm glass cut off filter (Schott) and a
water filter were used to filter off ultraviolet and infrared radiations, respectively.
2.1. Synthesis
2.1.1. 4-(Undecyloxy) phthalonitrile (1). 1-Dodecanol (1.10 g) was dissolved in dry
DMF (10 cm3) and then finely ground anhydrous K2CO3 (~2.00) was added. To this was
added dropwise 4-nitrophthalonitrile (1.00 g) in DMF (10 cm3) at 40 °C in N2 atmosphere.
The reaction mixture was stirred efficiently and monitored by thin-layer chromatography
(TLC) under inert atmosphere at 40–45 °C for 2 days. After the reaction mixture was
cooled to room temperature, it was poured into ca. 300 cm3 ice water. The creamy precipi-
tate was filtered and washed with water until washing became neutral. The crude product
was dissolved in CHCl3 and washed with 5% NaHCO3 to remove unreacted excess alcohol
compounds. The creamy solution was then dried with anhydrous Na2SO4 and filtered. The
solvent, CHCl3, was removed under reduced pressure giving a creamy powder. It was
chromatographed over silica gel column using a mixture of CHCl3 : MeOH (100/5) as elu-
ent, giving a hydroscopic oily solid, 4-(undecyloxy) phthalonitrile (1). Yield: 1.30 g
(75.11%). M.p.: oily at r.t. °C, IR (KBr) ν/cm−1: 3103, 3082, 3039 (w, Ar–H), 2918, 2850
(Aliph–CH2), 2229(st), 1602 (C=N), 1562 (C=C), 1473, 1396, 1309, 1294, 1282, 1249,
1093, 1020, 1001, 968, 914, 871, 833, 715; 1H NMR ([D6]-DMSO) δ: 8.02 (dd, 1H,
meta to Ar–OR and CN, phenyl H5), 7.67 (d, isomer, 1H, ortho to Ar–OR, phenyl
H4), 7.41 (d, 1H, Ar–H6), 4.11 (–CH2–O), 3.30 (DMSO), 2.12 (2H, CH2–CH2O),
1.73–1.40 (4H,OCH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3), 1.20–1.30 (16H,
CH2CH2CH2CH2CH2CH2CH2CH2CH3), 0.82 (3H, –CH2CH3); 13C NMR ([300 MHz, δ,
D6]-DMSO): 162.73 (C3, CH2–O), 136.43(Ar–C5), 134.92 (Ar–C6), 120.69 (Ar–C4),
116.956 (Ar–C2), 116.95 (C1, Ar–CN), 115.43(Ar–CN), 109.39 (Ar–CN), 69.69 (CH2O),
40.165 (DMSO), 33.23 (CH2CH2CH3), 29.72 –OCH2CH2(CH2)8CH2CH3 22.66(CH2CH3),
14.63 (CH3) ppm. Anal. Calcd for C20H28N2O (%): C, 76.88; H, 9.03; N, 8.97. Found (%):
C, 76.56; H, 9.45; N, 9.17. MALDI-MS: 313,5 [M + H]+.
2.1.2. [Zn] 2(3), 9(10), 16(17), 23(24)-tetrakis undecyloxy phthalocyanine (2). A mix-
ture of 1 (0.25 g) and 1,8-diazabicycloundec-7-ene (DBU) (0.05 cm3) in a sealed tube was
dissolved and heated with efficient stirring at 160 °C for 0.5 h under N2 in n-hexanol
(~1.0 cm3) and then anhydrous Zn(acac)2 (0.04 g, 0.24 mM) was added. After heating and
stirring for 6 h, the deep green–blue product was cooled to RT, and solid was washed suc-
cessively with hot MeOH and CH3CN, copious mixture of i-PrOH and water, cold CH3CN
to remove impurities until the filtrate was clear. The green–blue product was isolated by sil-
ica gel column chromatography with CHCl3–MeOH (20/1 v/v) as eluent. Complex 2 was
purified again with a second column chromatography over Sephadex (5% CH3OH/CHCl3,
eluent) and then dried in vacuum. Complex 2 is moderately soluble in CHCl3, CH2Cl2,

Lauryl alcohol phthalocyanines
353
THF, DMF, DMAA, and pyridine. Yield: 0.021 g (35%). M.p.: >200 °C. Anal. Calcd for
C80H112N8O4Zn (1313 g M−1): C, 73.06; H, 8.58; N, 8.52. Found: C, 73.56; H, 8.51; N,
9.02. IR (KBr) ν/cm−1: 3041 (Ar–H), 2924, 2852, 1643, 1604, 1582, 1487, 1463, 1386,
1361, 1336, 1278, 1228, 1192, 1118, 1085, 1047, 945, 873, 825, 746. 1H NMR
([D6]-DMSO) δ: 8.07 (d, br 1H, meta to Ar–OR and CN, phenyl H5), 7.84 (d, br, isomer,
1H, ortho to Ar–OR, phenyl H4), 7.73 (d, br, 1H, ortho to CN, Ar–H6), 4.08 (–CH2–O),
3.30 (DMSO), 2.15
(8H, CH2–CH2O),
1.75–1.45 (16H, OCH2CH2CH2
CH2CH2CH2CH2CH2CH2CH2 CH2CH2), 1.35–1.28 (16H,OCH2CH2CH2CH2CH2CH2CH2
CH2CH2CH2CH2CH3), 0.86 (12H, –OCH2CH2CH2CH2CH2CH2 CH2CH2CH2 CH2CH2
CH3). UV/Vis (THF, λmax nm−1: 679 (Q), 611(n–π*, sh), 350 (B); MS (MALDI-TOF,
dihydroxybenzoic acid (DHBA as matrix): m/z: 1314 [M + H]+.
2.1.3. [Ga] 2(3), 9(10), 16(17), 23(24)-tetrakis undecyloxy phthalocyanine (3). Com-
pound 1 (0.25 g) and anhydrous GaCl3 (0.015 g) in n-hexanol (~1.00 cm3) were heated to
reflux in a sealed tube under N2 for 6 h. The color of the mixture turned green–blue during
reflux. After heating was continued for an additional 2 h, the green–blue product was
cooled to room temperature after which the mixture was washed with MeOH. The crude
product was washed several times successively with first i-PrOH and then cold CH3CN to
remove impurities. Finally, the product was further purified by silica gel chromatography
with CHCl3/MeOH (20 : 1 v/v). This product is soluble in CHCl3, CH2Cl2, THF, DMF, and
pyridine. Yield: 0.013 g (21%). M.p.: >200 °C. Anal. Calcd for C80H112N8O4GaCl
(1353 g M−1): C, 70.91; H, 8.33; N, 8.27. Found: C, 72.7; H, 8.68; N, 8.42. FT-IR (KBr)
ν cm−1: 3042 (Ar–H), 2922, 2850 (Aliph–H), 1714, 1606, 1506, 1487, 1463, 1408, 1388,
1342, 1321, 1274, 1230, 1116, 1089, 1053, 1010, 950, 871, 823, 746. 1H NMR
([D6]-DMSO) δ: 8.02 (d, br 4H, meta to Ar–OR and CN, phenyl H5), 7.80 (d, br, isomer,
4H, ortho to Ar–OR, phenyl H4), 7.73 (d, br, 4H, ortho to CN, Ar–H6), 4.12 (–CH2–O),
3.30 (DMSO), 2.05 (8H, CH2–CH2O), 1.70–1.42 (16H, OCH2CH2CH2CH2 CH2CH2
CH2CH2CH2CH2 CH2CH2), 1.35–1.28 (16H, OCH2CH2 CH2CH2CH2CH2CH2CH2
CH2CH2CH2CH3), 0.88 (12H, -OCH2CH2CH2CH2CH2 CH2CH2 CH2CH2CH2CH2CH3).
UV–vis (THF), λmax nm−1: 695 (Q), 631 (n–π*), 344(B); MS (MALDI-TOF, dihydroxyben-
zoic acid (DHBA as matrix): m/z (%): 1354.5 [M + H]+.
2.1.4. [Ti] 2(3), 9(10), 16(17), 23(24)-tetrakis undecyloxy phthalocyanine (4). Com-
pound 1 (0.25 g), anhydrous Ti(OBu)4 (0.03 g), and DBU (0.05 cm3) in n-hexanol
(~1.00 cm3) were heated to reflux in a sealed tube under N2 for 6 h. After cooling to room
temperature and washing with i-PrOH it was filtered. The dark green–blue crude product
formed during the reaction was treated with i-PrOH several times and filtered off. It was
then successively washed with MeOH and CH3CN, and dried. Further purification by col-
umn chromatography with silica gel (CHCl3/MeOH as an eluent, 20/1 v/v) and dried in
vacuo. This phthalocyanine (4) is soluble in CHCl3, CH2Cl2, THF, DMF, and pyridine.
Yield: 0.018 g (30%). M.p.: >200 °C. Anal. Calcd for C80H112N8O5Ti (1313 g M−1): C,
73.14; H, 8.59; N, 8.53. Found: C, 74.01; H, 8.65; N, 8.89. FT-IR (KBr) ν/cm−1: 3028,
2922, 2852, 1714, 1604, 1556, 1487, 1463, 1386, 1338, 1276, 1230, 1118, 1070, 1024,
1
966, 871, 823, 748. H NMR ([D6]-DMSO) δ: 8.00 (d, br 4H, meta to Ar–OR and CN,
phenyl H5), 7.80 (d, br, isomer, 4H, ortho to Ar–OR, phenyl H4), 7.73 (d, br, 4H, ortho to
CN, Ar–H6), 4.06 (–CH2–O), 3.30 (DMSO), 2.00 (8H, CH2–CH2O), 1.70–1.42 (16H,

354
A.T. Bilgiçli et al.
OCH2CH2CH2CH2 CH2CH2CH2CH2 CH2CH2 CH2CH2), 1.35–1.28 (16H, OCH2CH2CH2
CH2CH2CH2CH2CH2CH2CH2CH2CH3), 0.86 (12H, –OCH2CH2 CH2CH2CH2CH2CH2
CH2CH2CH2CH2CH3). UV/Vis (THF, λmax nm−1: 700(Q), 629 (n–π*), 347(B); MS
(MALDI-TOF, dihydroxybenzoic acid (DHBA as matrix): m/z: 1314 [M + H]+.
2.2. Electrochemical in situ spectroelectrochemical and in situ electrocolorimetric
measurements
Cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements were carried
out with a 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 disk 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 tetrabutylammonium perchlorate
(TBAP) in extra pure dichloromethane (DCM) was employed as the supporting electrolyte
at a concentration of 0.10 M dm−3.
UV–vis absorption spectra and chromaticity diagrams were measured by an Ocean Optics
QE65000 diode array spectrophotometer. In situ spectroelectrochemical measurements were
carried out by utilizing a three-electrode configuration of a quartz thin-layer spectroelectro-
chemical 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 electro-colorimetric
measurements, under potentiostatic control, were obtained using an Ocean Optics QE65000
diode array spectrophotometer at color measurement emission mode by utilizing a three-
electrode configuration of the thin-layer quartz spectroelectrochemical cell. The standard
illuminant A with 2 degree observer at constant temperature in a light booth designed to
exclude external light was used. CIE standard illuminant A is intended to represent typical,
domestic, tungsten-filament lighting. Its relative spectral power distribution is that of a
Planckian radiator at a temperature of approximately 2856 K. Due to the nature of the dis-
tribution of cones in the eye, the tristimulus values depend on the observer’s field of view.
To eliminate this variable, the CIE defined the standard (colorimetric) observer. Originally
this was taken to be the chromatic response of the average human viewing through a 2°.
Thus, the CIE 1931 standard observer is also known as the CIE 1931 2° standard observer.
Prior to each set of measurements, background color coordinates (x, y, and z values) were
taken at open-circuit using the electrolyte solution without 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 end of each redox process were
reported.
2.3. Photodegradation quantum yields
Photodegradation quantum yield (Φd) determinations were carried out using the
experimental setup described [18–20]. Photodegradation quantum yields were determined
using formula 1,
ðC0 ꢀ CtÞ ꢁ V ꢁ NA
Ud ¼
(1)
Iabs ꢁ S ꢁ t

Lauryl alcohol phthalocyanines
355
where C0 and Ct are the sample concentrations before and after irradiation, respectively, V
is the reaction volume, NA is the Avogadro’s constant, S is the irradiated cell area, and t is
the irradiation time. Iabs is the overlap integral of the radiation source light intensity and the
absorption of the samples. A light intensity of 2.50 × 1016 photons s−1 cm−2 was employed
for Φd determinations.
3. Results and discussion
Although phthalocyanine complexes have low solubility in most organic solvents, phthalo-
cyanines bearing long aliphatic substituents on the Pc core increase the solubility. All syn-
thesized phthalocyanine derivatives (2–4) have excellent solubility in most organic solvents.
Ligand, 4-(undecyloxy) phthalonitrile (1), and its Zn(II), Ga(III), Ti(IV) phthalocyanines (2,
3, and 4) were prepared. Pcs (2–4) were accomplished by heating a pulverized mixture of
4-(undecyloxy) phthalonitrile with anhydrous Zn(O2CMe)2, GaCl3, and Ti(OBu)4 salts or
without metal salt at ca. 150–160 °C under N2 atmosphere in the presence of 1,8-diazabicy-
clo [5.4.0] undec-7-ene (DBU) for 6 h (scheme 1). The yields of these reactions were rather
low (35.60 for 2, 21.33 for 3, and 25.10% for 4). The phthalocyanines (2, 3, and 4) were
1
characterized by FT-IR, HNMR, UV/Vis and MALDI-TOF MS spectroscopic methods, as
well as by elemental analysis. All the analytical and spectral data are consistent with the
predicted structures.
Cyclotetramerization of 4-(undecyloxy) phthalonitrile to the phthalocyanines (2–4) was
confirmed by disappearance of the sharp –C≡N vibration at 2229 cm−1. IR spectra of
1
phthalocyanines (2–4) are very similar with the exception of small stretching shifts. The H
NMR spectra of 2, 3, and 4 are somewhat broader than the corresponding signals in the
starting 4-(undecyloxy) phthalonitrile (1) derivative. This broadening is likely due to chemi-
cal exchange caused by aggregation–disaggregation equilibria, and the fact that the product
obtained in these reactions is a mixture of positional isomers which are expected to show
chemical shifts that differ slightly from each other. The peripheral –OCH2 proton at
1
4.00–4.14 ppm in 1 and 2, and 3 and 4 was easily identified in the H NMR spectrum with
a broad chemical shift especially in the case of 2, 3, and 4 [11, 21, 22]. The other reso-
1
nances related to different CH2, CH3, and Ar–H protons in the H NMR spectra of 2, 3,
and 4 are very similar to those of the 4-(undecyloxy) phthalonitrile.
UV–vis spectra of the phthalocyanine complexes exhibit characteristic Q and B bands,
one in the visible region at ca. 600–750 nm (Q band) attributed to the π–π* transition from
HOMO to the LUMO of the Pc2− ring, and the other in the UV region at ca. 300–400 nm
(B-band) arising from the deeper π–π* transitions [10]. The ground state electronic spectra
of the compounds showed characteristic absorptions in the Q band region at 679 nm for 2,
695 nm for 3, and 700 for 4 in THF. B band absorptions of the metallophthalocyanines 2–4
were observed at 350, 344, and 347, respectively (figure 1).
The aggregation behaviors of 2, 3, and 4 were also investigated at different concentra-
tions in THF to determine aggregation that depends on concentration (figure 2 as an exam-
ple for (2). As shown in the figure, the Q band increases in intensity with increasing
concentration of 2 and no new band was observed due to the aggregated species [18, 19].
Beer–Lambert Law was obeyed for 2, 3, and
4 in the concentration range
6.95–25 × 10−6 M dm−3.

356
A.T. Bilgiçli et al.
Figure 1. UV–vis spectra of 2, 3 and 4 in THF.
Figure 2. Absorption spectra of ZnPc (2) in THF at different concentrations (inset: plot of absorbance vs.
concentration at 697 nm).
The bathochromic shift of the Q band due to the solvent for 2 increased in the following
order: THF < DMF < CHCl3 [figure 3(a)]. The electronic absorption spectra of 2 in these
solvents were analyzed using the method described originally by Bayliss [23]. Figure 3(b)
displays a plot of the Q band frequency versus the function (n2−1)/(2n2 + 1), where n is the
refractive index of the solvent. The positions of the Q bands in these solvents show almost

Lauryl alcohol phthalocyanines
357
Figure 3. Absorption spectra of 2 in different solvents (1.4 × 10−5 M) (a) and plot of the Q band frequency of 2
against (n2–1)/(2n2 + 1) (b), where n is the refractive index of the solvent.
a linear dependence on this function. This linearity suggests that shifts are mainly due to
solvation and not to a ligation effect [24].
The degradations of the phthalocyanine molecules were performed. The determination of
the degradation of the molecules under irradiation is especially important for use as photo-
catalysts. The spectral changes obtained for all the studied phthalocyanine compounds (2,
3, and 4) in DMF during light irradiation are as shown in figure 4 (using complex 2 as an
example). The collapse of the absorption spectra without any distortion of the shape
confirms photodegradation not associated with phototransformation for 2, 3, and 4. The
photodegradation quantum yield (Φd) values for the complexes listed in n are of the order
of 10−4. Stable ZnPc molecules show values as low as 10−6, and for unstable molecules,

358
A.T. Bilgiçli et al.
Figure 4. Absorption changes during the photodegradation studies of 2 in DMF showing the disappearance of the
Q band at 10 min intervals (inset: plot of absorbance vs. time).
values of the order 10−3 have been reported [25]. Photodegradation quantum yields of 2, 3,
and 4 have an average stability under applied light.
The morphology of thin film is important for electronic devices, and therefore, we exam-
ined the surface morphology of 2, 3, and 4. Figure 5 shows 3-D AFM image of the 2, 3,
and 4 phthalocyanine thin films (table 1).
3.1. Voltammetric characterization
Solution redox properties of ZnPc (2), GaPc (3), and TiOPc (4) were obtained in DCM/
TBAP electrolyte system on a Pt working electrode. Table 2 lists the assignments of the
redox couples and estimated electrochemical parameters including the half-wave peak
potentials (E1/2), ratio of the anodic to the cathodic peak currents (Ip,a/Ip,c), peak-to-peak
potential separations (ΔEp), and difference between the first oxidation and reduction pro-
cesses (ΔE1/2). ΔE1/2 reflects the HOMO–LUMO gap for metal free Pcs, and it is related
with the HOMO–LUMO gap in MPc species having redox inactive metal centers. Peak-to-
peak separations, E1/2 and ΔE1/2 values are in agreement with the reported data for redox
processes of the metallophthalocyanine complexes [26–31].
Complexes 2 and 3 have both redox inactive metal centers and indicate very similar Pc
ring-based electron transfer processes; thus, CV and SWV of GaPc (2) are given in figure 6
as representative of these complexes. Within the electrochemical window of DCM/TBAP, 3
has two one-electron oxidation and two one-electron reduction processes. For the first and
second reduction couples, the anodic-to-cathodic peak separations (ΔEp) changed from 90
to 210 mV with scan rates from 10 to 500 mV s−1, indicating electrochemical irreversibility
of these electron transfer processes. Irreversibility of these processes is illustrated by the
shifting of the symmetry of the forward and reverse SWVs (figure 6) [32]. Unity of the

Lauryl alcohol phthalocyanines
359
Figure 5. 3-D AFM image of ZnPc (2), GaPc (3) and TiPc (4).
Table 1. Photochemical properties of 2, 3
and 4 in DMF.
Complex
Solvent
Φd (10−3
)
2
3
4
DMF
DMF
DMF
0.3
0.2
0.2
Ipa/Ipc ratio with the scan rate and linear variation of the Ipc with square root of the scan
rates indicated diffusion-controlled electron transfer mechanism of these processes. Oxida-
tion processes are chemically and electrochemically irreversible completely, since they did
not give cathodic couples during CV measurement. Observation of the cathodic couples of

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A.T. Bilgiçli et al.
Table 2. Voltammetric data of the complexes.
Complex
Ring oxidations
TiIVO/TiIII
O
TiIIIO/TiIIO Ring reductions dΔE1/2 Ref.
ZnPc
aE1/2 vs. SCE
bΔEp (mV)
cIpa/Ipc
0.98e
–
–
1.40
–
–
1.42 0.82 (1.08)
–
–
0.71
105
0.77
0.83
–
−0.88 −1.33
1.59
1.68
1.46
120
155
Tw
Tw
Tw
0.89
0.84
GaPc
aE1/2 vs. SCE
bΔEp (mV)
cIpa/Ipc
−0.85 −1.20
110
0.92
−1.45e
–
158
0.90
–
TiOPc
aE1/2 vs. SCE
bΔEp (mV)
cIpa/Ipc
−0.64
62
0.97
−0.99
68
0.86
–
–
–
aE1/2 = (Epa + Epc)/2 at 0.100 Vs−1
bΔEp = |Epa − Epc| at 0.100 Vs−1
.
.
cIpa/Ipc for reduction, Ipc/Ipa for oxidation processes at 0.100 Vs−1 scan rate.
dΔE1/2 = ΔE1/2 (first oxidation) −ΔE1/2 (first reduction) = HOMO–LUMO gap for metallophthalocyanines having electro-inactive
metal center (metal to ligand (MLCT) or ligand to metal (LMCT) charge transfer gap for MPc having redox active metal center.
eThe process is recorded with SWV.
Tw: This work.
Figure 6. CVs and SWV of GaPc (5.0 × 10−4 M dm−3) at 0.100 mV s−1 scan rate on Pt in DCM/TBAP (SWV
parameters: pulse size = 100 mV; step size: 5 mV; frequency: 25 Hz).
the oxidation processes during SWV measurements indicates effects of the time scale of the
voltammetric methods to the reversibility of these electron transfer processes (figure 6).
Assignments of the redox couples are performed by spectroelectrochemical measurements
given below.
Figure 7 shows CV SWVs of TiPc (4). Within the potential windows, two oxidation pro-
cesses labeled as O1 at 0.81 V and O2 at 1.41 V and three reduction processes labeled as R1
at −0.63 V, R2 at −0.99 V, and R3 at −1.45 V are observed. An unusual wave at 1.10 V is
recorded at fast scan rates. We could not perform assignments of this wave due to decompo-
sition of the complex under controlled potential during spectroelectrochemical measurement
(given below). Unity of the Ip,a/Ip,c ratios of the R1 and R2 couples at all scan rates indicate
purely diffusion-controlled and chemically reversible behavior of the processes. ΔEp values
of these processes are in the electrochemical reversibility range. However, R3 and oxidation

Lauryl alcohol phthalocyanines
361
Figure 7. (a) CVs of TiOPc (5.0 × 10−4 M dm−3) at various scan rates on Pt in DCM/TBAP. (b) SWV of TiOPc,
SWV parameters: pulse size = 100 mV; step size: 5 mV; frequency: 25 Hz.
processes are not chemically reversible with respect to the Ip,a/Ip,c ratio. Moreover,
reversibility of the processes can be concluded with respect to symmetry and unity of the
peak current ratios for the waves recorded during the forward and reverse SWV scans
[figure 7(b)] [32].
3.2. In situ spectroelectrochemical measurements
Spectroelectrochemical studies were also employed to confirm the assignments in the CVs
of MPcs. Figure 8 represents the in situ UV–vis spectral changes and in situ recorded
chromaticity diagram of GaPc in DMSO/TBAP during potential applications at the poten-
tials of the redox processes. There isn’t any study illustrating the in situ spectroelectrochem-
ical behavior of GaPcs in the literature; thus, this is the first article representing the in situ
spectroelectrochemical changes of GaPc. Figure 8(a) illustrates the spectral changes during
the first reduction process (Eapp = −1.00 V). While the Q band at 698 nm decreases in
intensity, two new bands enhance at 584 and 634 nm. The band at 634 nm increases and
then shifts to higher energy side of the spectra. The band at 390 nm and the B band at

362
A.T. Bilgiçli et al.
Figure 8. In situ UV–vis spectral changes of GaPc in DCM/TBAP electrolyte. (a) Eapp = −1.00 V. (b)
Eapp = 1.00 V. (c) Chromaticity diagram of GaPc (each symbol represents the color of electro-generated species;
□: [Cl–GaIIIPc−2], △: [Cl–GaIIIPc−3 −1, ∇: [GaIIIPc−2 +1
] ] .

Lauryl alcohol phthalocyanines
363
Figure 9. In situ UV–vis spectral changes of TiOPc in DCM/TBAP electrolyte. (a) Eapp = −0.75 V. (b)
Eapp = −1.25 V (inset: Eapp = −1.75 V). (c) Eapp = 1.00 V. (d) Chromaticity diagram of CoPc (each symbol repre-
sents the color of electro-generated species; □: [TiIVOPc−2], ○: [TiIIIOPc−2 −1, △: [TiIIOPc−2 −2, ∇: [TiIIOPc−3 −3
] ] ] ,
✩: [TiIVOPc−2 +1
] .
306 nm increase slightly in intensity. These spectral changes are similar with the spectral
changes of ring-based reduction process of MPc having redox inactive metal centers
[26–31]. Thus, we can assign this process to a ring-based reduction, [Cl–GaIIIPc−2]/
[Cl–GaIIIPc−3]1−. The only difference is the band at 634 nm. While the Q band decreases in
intensity without shift, a new band is recorded between 500 and 600 nm during the first
reduction process of MPc having redox inactive metal centers [33–38]. These changes are
also recorded with GaPc; however, an extra band is recorded at 634 nm. We have observed
well-defined isosbestic points at 638 and 783 nm. These isosbestic points demonstrate that
the reduction proceeds cleanly in deoxygenated DCM to give a single, reduced species.
Further reduction of the complex under applied potential at −1.40 V indicated the
[Cl–GaIIIPc−3]1−/[Cl–GaIIIPc−4]2− process. During the first oxidation of the complex, the Q
band decreases without shift and two new bands increase at 512 and 871 nm [figure 8(b)],

364
A.T. Bilgiçli et al.
Scheme 1. Synthetic route of 2(3), 9(10), 16(17), 23(24)-tetrakis undecyloxy phthalocyanine M{Pc[O-(CH2)11CH3)]4}
(M = Zn(2), Ga(3), Ti(4)).
which indicates a ring-based oxidation process. During the second oxidation reaction, spec-
tral changes indicated decomposition of the complex at the end of the oxidation process.
The color change of the solution of the complexes during the redox processes was recorded
using in situ colorimetric measurements without any potential application. The solution of
[Cl–GaIIIPc−2] is bluish green (x = 0.311 and y = 0.3809) [figure 8(c)]. As the potential is
stepped from 0 to −1.00 V, color of the neutral [Cl–GaIIIPc−2] changes and light blue color
(x = 0.2796 and y = 0.3165) for monoanionic form of [Cl–GaIIIPc−3]1− was obtained at the
end of the first reduction. During the oxidation process, color of the complex is slightly
decreased and a light green color (x = 0.3352 and y = 0.3761) is recorded for the monocat-
ionic species, [Cl–GaIIIPc−1]1+.
Figure 9 shows in situ UV–vis spectral changes of the neutral and electro-generated spe-
cies during the reduction/oxidation processes of [TiIVOPc−2] (4). During the controlled
potential reduction of 4 at −0.75 V [figure 9(a)], while the absorption of the Q band corre-
sponding to the neutral [TiIVOPc−2] species decreases without shift, a new band is recorded
at 594 nm. At the same time, a new band corresponding to the electro-generated species
appears at 950 nm. As shown in figure 9(a), the process occurred with clear isosbestic
points at 411, 454, 636, and 766 nm in the spectra which demonstrate that there is no chem-
ical reaction complicating the electron transfer reaction. These spectral changes are typical
for a metal-based reduction of titanyl phthalocyanine complexes [37, 39–41]. During the
controlled potential reduction of 4 at −1.25 V, the absorption for the Q band at 594 nm

Lauryl alcohol phthalocyanines
365
shifts to 586 nm with decreasing intensity, while a new band is recorded at 553 nm. During
this potential application, the bands at 965 nm decrease in intensity, while a new band is
recorded at 915 nm. These spectral changes are easily assigned to the [TiIIIOPc−2]−1/
[TiIIOPc−2]−2 redox process [figure 9(b)] [37, 39–41]. This process has isosbestic points at
444, 580, and 803 nm in the spectra. During further reduction of the complex at −1.75 V,
spectral changes indicate a Pc-based reduction process [figure 9(b) inset]. The spectral
changes given in figure 9(c) indicate Pc ring reduction under the applied potential at
−1.90 V. Complex 4 oxidized to [TiIVOPc−1]1+ and then decomposes under the applied
potential at 0.80 V, because while the Q band decreases in intensity without shift, new
bands increase at 535 and 877 nm. However, these new bands could not increase due to
decomposition of the oxidized species [figure 9(c)]. Color changes of 4 in solution during
the redox processes were recorded with in situ electrocolorimetric measurements and are
given in figure 9(d).
4. Conclusion
The synthesis of new soluble metallophthalocyanine complexes [Zn(II), Ga(III), and Ti(IV)]
1
2–4 was characterized by FT-IR, HNMR, 13CNMR, UV–vis, and MALDI-MS spectra, and
also surface morphologies were determined by AFM. Voltammetric and spectroelectrochem-
ical studies indicate that while zinc and gallium phthalocyanines have only ring-based,
multi-electron, redox processes, titanium phthalocyanine gives both metal and ring-based
reduction processes. Definite determination of the colors of the electrogenerated anionic and
cationic forms of the complexes with chromaticity measurements is important to decide the
possible electrochromic application of the complexes. Different color of the electrogenerat-
ed species indicates their possible application in display technologies, e.g. electrochromic
and data storage applications.
Acknowledgements
We thank the research fund of Sakarya University and TUBİTAK (Project No: BAP-2013-
02-04-049, Project No: TBAG-108T094).
References
[1] F.I. Bohrer, C.N. Colesniuc, J. Park, I.K. Schuller, A.C. Kummel, W.C. Trogler. J. Am. Chem. Soc., 130, 3712
(2008).
[2] B.A. Minch, W. Xia, C.L. Donley, R.M. Hernandez, C. Carter, M.D. Carducci, A. Dawson, D.F. O’Brien,
N.R. Armstrong. Chem. Mater., 17, 1618 (2005).
[3] M. Kimura, T. Muto, H. Takimoto, K. Wada, K. Ohta, K. Hanabusa, H. Shirai, N. Kobayashi. Langmuir, 16,
2078 (2000).
[4] M.N. Sibata, A.C. Tedesco, J.M. Marchetti. Eur. J. Pharm. Sci., 23, 131 (2004).
[5] K. Ishii, M. Shiine, Y. Shimizu, S. Hoshino, H. Abe, K. Sogawa, N. Kobayashi. J. Phys. Chem. B, 112, 3138
(2008).
[6] H.S. Majumdar, A. Bandyopadhyay, A.J. Pal. Org. Electron., 4, 39 (2003).
[7] D. Dini, M. Hanack, H.-J. Egelhaaf, J.C. Sancho-Garcia, J. Cornil. J. Phys. Chem. B, 109, 5425 (2005).
[8] A.D. Dinsmore, M.F. Hsu, M.G. Nikolaides, M. Marquez, A.R. Bausch, D.A. Weitz. Science, 298, 1006
(2002).

366
A.T. Bilgiçli et al.
[9] M.F. Craciun, S. Rogge, A.F. Morpurgo. J. Am. Chem. Soc., 127, 12210 (2005).
[10] C.C. Leznoff, A.B.P. Lever. In Phthalocyanines: Properties and Applications, C.C. Leznoff, A.B.P. Lever
(Eds), Vol. 1–4, pp. 86–90, VCH, Weinheim (1989–1996).
[11] M.N. Yaraşir, M. Kandaz, A. Koca, B. Salih. Polyhedron, 26, 1139 (2007).
[12] L.A. Ehrlich, P.J. Skrdla, W.K. Jarrell, J.W. Sibert, N.R. Armstrong, S.S. Saavedra, A.G.M. Barrett, B.M.
Hoffman. Inorg. Chem., 39, 3963 (2000).
[13] S.L.J. Michel, A.G.M. Barrett, B.M. Hoffman. Inorg. Chem., 42, 814 (2003).
[14] M.N. Yaraşır, M. Kandaz, A. Koca, B. Salih. J. Porphyrins Phthalocyanines, 10, 1022 (2006).
[15] M.N. Yarasır, M. Kandaz, B.F. Filiz Şenkal, A. Koca, B. Salıh. Dyes Pigm., 77, 7 (2008).
[16] P. Tau, T. Nyokong. Polyhedron, 25, 1802 (2006).
[17] M. Kandaz, Ö. Bekarolu. Chem. Ber., 130, 1833 (1997).
[18] J.H. Brannon, D. Magde. J. Am. Chem. Soc., 102, 62 (1980).
[19] A. Ogunsipe, T. Nyokong. J. Photochem. Photobiol. A: Chem., 173, 211 (2005).
[20] I. Seotsanyana-Mokhosi, N. Kuznetsova, T. Nyokong. J. Photochem. Photobiol. A: Chem., 140, 215 (2001).
[21] J. Simon, P. Bossoul. In , Phthalocyanines: Properties and Applications, C.C. Leznoff, A.B.P. Lever (Eds),
Vol. 2, pp. 223–225, VCH, New York (1993).
[22] M. Ozcesmeci, I. Ozcesmeci, E. Hamuryudan. Polyhedron, 29, 271 (2010).
[23] N.S. Bayliss. J. Chem. Phys., 18, 292 (1950).
[24] W.F. Law, R.C.W. Liu, J.H. Jiang, D.K.P. Ng. Inorg. Chim. Acta, 256, 147 (1997).
[25] S. Maree, T. Nyokong. J. Porphyrins Phthalocyanines, 5, 782 (2001).
[26] A.B.P. Lever, P.C. Minor, J.P. Wilshire. Inorg. Chem., 20, 2550 (1981).
[27] B. Akkurt, A. Koca, E. Hamuryudan. New J. Chem., 33, 2248 (2009).
[28] Ö.A. Osmanbaş, A. Koca, İ. Özçeşmeci, Aİ. Okur, A. Gül. Electrochim. Acta, 53, 4969 (2008).
[29] A. Koca, M. Özçeşmeci, E. Hamuryudan. Electroanalysis, 22, 1623 (2010).
[30] M. Özer, A. Altındal, A.R. Özkaya, M. Bulut, Ö. Bekaroğlu. Polyhedron, 25, 3593 (2006).
[31] A.B.P. Lever, E.R. Milaeva, G. Speier. In Phthalocyanines: Properties and Applications, C.C. Leznoff and
A.B.P. Lever (Eds), Vol 3, pp. 5–27. VCH, New York (1993).
[32] P.T. Kissinger, W.R. Heineman. Laboratory Techniques in Electroanalytical Chemistry, 2nd Edn, pp. 51–163,
Marcel Dekker, New York (1996).
[33] L.D. Rollmann, R.T. Iwamoto. J. Am. Chem. Soc., 90, 1455 (1968).
[34] D. Kulaç, M. Bulut, A. Altındal, A.R. Özkaya, B. Salih, Ö. Bekaroğlu. Polyhedron, 26, 5432 (2007).
[35] A. Koca, Ş. Bayar, H.A. Dinçer, E. Gonca. Electrochim. Acta, 54, 2684 (2009).
[36] N. Nombona, T. Nyokong. Dyes Pigm., 80, 130 (2009).
[37] G. Mbambisa, P. Tau, E. Antunes, T. Nyokong. Polyhedron, 26, 5355 (2007).
[38] A. Alemdar, A.R. Özkaya, M. Bulut. Polyhedron, 28, 3788 (2009).
[39] A. Koca, A.R. Özkaya, Y. Arslanoğlu, E. Hamuryudan. Electrochim. Acta, 52, 3216 (2007).
[40] P. Tau, T. Nyokong. Dalton Trans., 4482 (2006).
[41] P. Tau, T. Nyokong. Polyhedron, 25, 1802 (2006).