Tetra-2-[2-(dimethylamino)ethoxy]ethoxy substituted zinc phthalocyanines and their quaternized analoques: Synthesis, characterization, photophysical and photochemical properties

Article abstract of DOI:10.1016/j.jphotochem.2011.05.006

The new peripherally and non-peripherally tetra-2-[2-(dimethylamino)ethoxy] ethoxy substituted zinc (II) phthalocyanine complexes (2 and 4) and their quaternized amphiphilic derivatives (2a and 4a) have been synthesized and characterized for the first tim

Full text of DOI:10.1016/j.jphotochem.2011.05.006

Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
Contents lists available at ScienceDirect
Journal of Photochemistry and Photobiology A:
Chemistry
journal homepage: www.elsevier.com/locate/jphotochem
Tetra-2-[2-(dimethylamino)ethoxy]ethoxy substituted zinc phthalocyanines and
their quaternized analoques: Synthesis, characterization, photophysical and
photochemical properties
Zekeriya Bıyıklıog˘lua, Mahmut Durmus¸ b,∗, Halit Kantekina
a Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
b Gebze Institute of Technology, Department of Chemistry, P.O. Box 141, Gebze 41400, Kocaeli, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
The new peripherally and non-peripherally tetra-2-[2-(dimethylamino)ethoxy]ethoxy substituted zinc
(II) phthalocyanine complexes (2 and 4) and their quaternized amphiphilic derivatives (2a and 4a) have
been synthesized and characterized for the first time. The quaternized complexes show excellent sol-
ubility in both organic and aqueous solutions, which makes them potential photosensitizer for use
in photodynamic therapy (PDT) of cancer. Photophysical (fluorescence quantum yields and lifetimes)
and photochemical (singlet oxygen generation and photodegradation under light irradiation) proper-
ties of these novel phthalocyanines are investigated in dimethylsulfoxide (DMSO) for non-quaternized
complexes and in DMSO, phosphate buffered solution (PBS) or PBS + triton X-100 (TX) for quaternized
complexes. In this study, the effects of the aggregation of the molecules, quaternization and posi-
tion (peripherally or non-peripherally) of the substituents and nature of the solvents (DMSO, PBS or
PBS + triton X-100) on the photophysical and photochemical parameters of the zinc (II) phthalocya-
nines are also reported. A spectroscopic investigation of the binding of the quaternized cationic zinc
(II) phthalocyanine complexes to bovine serum albumin (BSA) is also presented in this work.
© 2011 Elsevier B.V. All rights reserved.
Received 29 March 2011
Received in revised form 10 May 2011
Accepted 21 May 2011
Available online 30 May 2011
Keywords:
Phthalocyanine
Water soluble
Zinc
Singlet oxygen
Photodynamic therapy
Photosensitizer
1. Introduction
sensitizer, one important goal is to maintain a balance of enough
hydrophilicity for it to dissolve in aqueous solutions, and enough
One of the main targets in the chemistry of the phthalocya-
nines and their metallic complexes is the development of new
materials that open new opportunities in advanced functional
molecular materials such as catalysis, biomedicine, electronic and
optoelectronic devices [1,2]. One of these new opportunities is
using phthalocyanines in photodynamic therapy (PDT) of cancer
as second generation photosensitizers [3].
Traditional cancer therapies such as surgery, chemotherapy and
radiation therapy involve a delicate balance between removing or
destroying diseased tissue and sparing surrounding healthy cells.
These conventional treatments cause serious effects due to the
death of normal cells by indiscriminate cytotoxic properties. PDT is
an alternative method in the treatment of cancer therapies. Three
fundamental requirements for PDT are oxygen, light and photosen-
sitizer [4]. Each factor is harmless by itself, but their combination
can produce cytotoxic agents such as singlet oxygen. The photo-
dynamic activation often begins with an intravenous injection of a
photosensitizer, such as phthalocyanines. In the design of a photo-
hydrophobicity for it to partition into malignant cells. Whereas,
introduction of hydrophilic groups into substituted phthalocyanine
derivatives was performed in order to be soluble in aqueous media,
water solubility of phthalocyanine derivatives has a strong influ-
ence on the bioavailability and in vivo distribution [5,6]. In PDT
administration, the drug is injected into the patient’s blood stream,
and since the blood itself is a hydrophilic system. The amphiphilic
phthalocyanine derivatives are considered the best compounds for
a new generation of photosensitizers for PDT [7,8]. Enhancement of
the amphiphilicity of the phthalocyanine with the introduction of
hydrophobic groups proved to increase the cell penetration [9,10].
Once the photosensitizer has been administered, and the sensitizer
has reached the cells in question, the affected area is irradiated by
light of wavelength appropriate for the sensitizer. Light absorbed
by the sensitizer excites it, and the absorbed energy is transmitted
to molecular oxygen (e.g., Type II mechanism) in its ordinary triplet
ground state whereby it is excited into its singlet level. Within the
cell, the hydrophobic lipid bilayer is considered to be the uptake
location and locus of action of hydrophobic sensitizers [11].
An ideal photosensitizer has to localized in tumor tissue, be
able to produce high singlet oxygen generation, possess a large
absorption coefficient at wavelengths greater than 650 nm and
∗
Corresponding author. Tel.: +90 262 6053075; fax: +90 262 6053101.
E-mail address: durmus@gyte.edu.tr (M. Durmus¸ ).
1010-6030/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jphotochem.2011.05.006

88
Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
have no dark toxicity. The first photosensitizers are hematopor-
phyrin derivatives and have already been described in detail in
several articles [12,13]. Second generation photosensitizers such
as phthalocyanines have also been introduced for PDT in research
and clinical trials [14]. Photosens®, which is a mixture of sulfonated
aluminium (III) phthalocyanines, is clinically used in Russia for
the treatment of a range of cancers [15]. Pcs are known to be
useful photosensitizers due to their high molar absorption coef-
ficient in the red part of the spectrum, photostability and long
lifetimes of the photoexcited triplet states [16–19]. Especially, zinc
phthalocyanines (ZnPcs) have been extensively studied since the
d10 configuration of the central Zn2+ ion. ZnPcs have intensive long
wavelength absorption and high singlet and triplet yields, which
make them valuable photosensitizer for PDT applications.
The photophysics and photochemistry of ZnPc complexes are
well documented [20–25]. Such studies reveal that these com-
plexes show great promise for photocatalytic and photosensitizing
applications [26,27]. However, studies on amphiphilic ZnPc com-
plexes are scarce in the literature [7,28–34]. The advantages that
go with amphiphilic phthalocyanines are too striking to over-
look, hence our interest in these complexes. The aim of our
ongoing research is to synthesis amphiphilic ZnPc complexes to
be used as potential PDT agents, since ZnPc complexes show
good photophysical and photochemical properties which are very
useful for PDT studies. Herein, we report the synthesis, character-
ization and spectroscopic characterization, aggregation behavior
as well as photophysical (fluorescence quantum yields and life-
times) and photochemical (singlet oxygen and photodegradation
quantum yields) properties of ZnPc complexes tetra-substituted
at the peripheral (2) and non-peripheral (4) positions with 2-
[2-(dimethylamino)ethoxy]ethoxy group (Scheme 1) and their
quaternized (2a for peripheral, and 4a for non-peripheral position)
complexes (Scheme 2).
and emission spectra were recorded on a Varian Eclipse spectroflu-
orometer using 1 cm pathlength cuvettes at room temperature.
Photo-irradiations were done 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 radia-
tions, respectively. An interference filter (Intor, 670 nm with a band
width of 40 nm) was additionally placed in the light path before the
sample. Light intensities were measured with a POWER MAX5100
(Molelectron detector incorporated) power meter.
2.3. Photophysical parameters
2.3.1. Fluorescence quantum yields and lifetimes
Fluorescence quantum yields (˚F) were determined by the com-
parative method using equation given in the references [40,41].
Unsubstituted ZnPc (in DMSO) (˚F = 0.20) [42] was employed as
the standard. The absorbance of the solutions at the excitation
wavelength ranged between 0.04 and 0.05.
Natural radiative lifetimes (ꢀ0) were determined using Pho-
tochemCAD program which uses the Strickler–Berg equation [43].
The fluorescence lifetimes (ꢀF) were evaluated using Eq. (1).
ꢀF
˚
F
=
(1)
ꢀ0
2.4. Photochemical parameters
2.4.1. Singlet oxygen quantum yields
Singlet oxygen quantum yield (˚ꢁ) determinations were car-
ried out using the experimental set-up described in literature
[44,45]. Typically, a 3 mL portion of the respective unsubstituted,
peripherally and non-peripherally tetra-substituted ZnPc solu-
tions (concentration = 1 × 10−5 M) containing the singlet oxygen
quencher was irradiated in the Q band region with the photo-
irradiation set-up described in Refs. [44,45]. ˚ꢁ values were
determined in air using the relative method with ZnPc (in DMSO)
or ZnPcSmix (in aqueous media) as references. DPBF and ADMA
were used as chemical quenchers for singlet oxygen in DMSO and
aqueous media, respectively. The ˚ꢁ values of the studied ZnPc
complexes were calculated using equation given in the Ref. [45].
Unsubstituted ZnPc (˚Sꢁtd = 0.67 in DMSO) [46] and sulfonated
Bovine serum albumin (BSA) and human serum albumin (HSA)
are major plasma proteins, which contribute significantly to physi-
ological functions and display effective drug delivery roles [35,36],
hence the investigation of binding of drugs with albumin is of inter-
est. A spectroscopic investigation of the binding of the amphiphilic
ZnPc complexes (2a and 4a) to BSA is also presented in this work.
ZnPc (ZnPcSmix, ˚Std = 0.45 in aqueous media) [45] were used as
standard. To avoidꢁchain reactions induced by DPBF (or ADMA) in
the presence of singlet oxygen [47], the concentration of quenchers
(DPBF or ADMA) was lowered to ∼3 × 10−5 M. Solutions of sensi-
tizer (concentration = 1 × 10−5 M) containing DPBF (or ADMA) were
prepared in the dark and irradiated in the Q band region using the
setup described in literature [44,45]. DPBF degradation at 417 nm
and ADMA degradation at 380 nm were monitored. The light inten-
sity 6.57 × 1015 photons s−1 cm−2 was used for ˚ꢁ determinations.
2. Experimental
2.1. Materials
All reagents and solvents were of reagent grade quality and were
obtained from commercial suppliers. Unsubstituted zinc phthalo-
cyanine and 2-[2-(dimethylamino)ethoxy]ethanol were purchased
from Aldrich. 9,10-Antracenediyl-bis(methylene)dimalonoic acid
(ADMA) and 1,3-diphenylisobenzofuran (DPBF) were purchased
from Fluka. All solvents were dried and purified as described
by Perrin and Armarego [37]. 4-Nitrophthalonitrile [38] and 3-
nitrophthalonitrile [39] were synthesized and purified according
to well known literature.
2.4.2. Photodegradation quantum yields
Photodegradation quantum yield (˚d) determinations were
carried out using the experimental set-up described in literature
[44,45]. Photodegradation quantum yields were determined using
Eq. (2),
2.2. Equipment
(C0 − Ct)
V NA
˚
=
(2)
The IR spectra were recorded on a Perkin Elmer 1600 FT-IR
spectrophotometer using KBr pellets. 1H and 13C NMR spectra
were recorded on a Varian Mercury 200 MHz spectrometer in
CDCl3. Chemical shifts were reported (ı) relative to Me4Si as
internal standard. Mass spectra were measured on a Micromass
Quatro LC/ULTIMA LC–MS/MS spectrometer. Melting points were
measured on an electrothermal apparatus and are uncorrected.
Absorption spectra in the UV–visible region were recorded with
a Shimadzu 2001 UV spectrophotometer. Fluorescence excitation
d
Iabs
S t
where C0 and Ct are the samples concentrations before and after
irradiation, respectively, V is the reaction volume, NA the Avo-
gadro’s constant, S the irradiated cell area and t the irradiation
time, Iabs is the overlap integral of the radiation source light
intensity and the absorption of the samples. A light intensity
of 2.19 × 1016 photons s−1 cm−2 was employed for ˚d determina-
tions.

Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
89
OR
N
N
O2N
CN
CN
N
N
N
RO
CN
CN
ROH, DMF
Zn(OAc)2, n-pentanol
DBU, 160oC
OR
Zn
N
N
RO
K2CO3, 50oC
N
1
OR
O
N
R =
2
RO
OR
N
N
N
CN
CN
CN
CN
ROH, DMF
Zn(OAc)2, n-pentanol
DBU, 160oC
N
N
Zn
N
N
N
K2CO3, 50oC
NO2
OR
OR
3
OR
4
Scheme 1. Synthesis of tetra-2-[2-(dimethylamino)ethoxy]ethanol substituted zinc phthalocyanine complexes.
values of KSBVSA obtained from the plots of F0BSA/FBSA versus [Pc], the
value of kq may be determined using Eq. (5).
2.4.3. Binding of quaternized zinc phthalocyanine complexes to
BSA
The binding of the quaternized ZnPc complexes (2a and 4a)
to BSA was studied by spectrofluorometry at room temperature.
An aqueous solution of BSA (fixed concentration) was titrated
with varying concentrations of the respective quaternized ZnPc
solutions. BSA was excited at 280 nm and fluorescence recorded
between 290 nm and 500 nm. The steady diminution in BSA flu-
orescence with increase in quaternized ZnPc concentrations was
noted and used in the determination of the binding constants and
the number of binding sites on BSA, according to Eq. (3) [48–50].
2.5. Synthesis
2.5.1. 4-{2-[2-(dimethylamino)ethoxy]ethoxy}phthalonitrile (1)
4-Nitrophthalonitrile (0.5 g, 2.89 mmol) was dissolved
in anhydrous DMF (25 mL) under nitrogen and 2-[2-
(dimethylamino)ethoxy]ethanol (1.15 g, 8.67 mmol) was added.
After stirring for 10 min, finely ground anhydrous K2CO3 (3.98 g,
28.9 mmol) was added in portions over 2 h with stirring. The
reaction mixture was stirred at 50 ◦C for 72 h under nitrogen. Then
water (100 mL) was added and the aqueous phase extracted with
chloroform (3 × 100 mL). The combined extracts were treated with
water and dried over anhydrous magnesium sulfate and then
filtered. Solvent was evaporated and the product was crystallized
from ethanol. Yield: 0.3 g (40%), mp: 130–132 ◦C. IR (KBr pellet),
ꢂmax/cm−1: 3092 (Ar–H), 2953–2846 (Aliph. C–H), 2229 (C N),
1603, 1564, 1493, 1310, 1255, 1163, 1098, 1021, 882, 834, 693,
636, 524. 1H NMR. (CDCl3), (ı:ppm): 7.71 (d, 1H, Ar–H), 7.30 (s, 1H,
Ar–H), 7.19 (d, 1H, Ar–H), 4.21 (t, 2H, –CH2–O–Ar–), 3.83 (t, 2H,
–CH2–O–), 3.62 (t, 2H, –CH2–O–), 2.51 (t, 2H, –CH2–N), 2.25 (s, 6H,
CH3). 13C NMR. (CDCl3), (ı:ppm): 157.45, 130.69, 115.38, 115.01,
112.38, 111.29, 110.82, 102.29, 64.74, 64.26, 64.05, 54.01, 41.12.
MS (ES+), (m/z): 259 [M]+.
ꢀ
ꢁ
(F0 − F)
(F − F
log
= log Kb + n log Pc
(3)
[
]
)
∞
where F0 and F are the fluorescence intensities of BSA in the
absence and presence of quaternized ZnPc complexes (2a and 4a),
respectively; F , the fluorescence intensity of BSA saturated with
∞
quaternized ZnPc complexes; Kb, the binding constant; n, the num-
ber of binding sites on a BSA molecule; and [Pc] the concentration of
quaternized ZnPc complexes. Plots of log[(F − F)/(F − F )] against
∞
0
log[Pc] would provide the values of n (from the slope) and Kb (from
the intercept). The changes in BSA fluorescence intensity were
related to quaternized ZnPc concentrations by the Stern–Volmer
relationship (Eq. (4)):
F0BSA
FBSA
= 1 + KSBVSA[Pc]
(4)
2.5.2. 3-{2-[2-(dimethylamino)ethoxy]ethoxy}phthalonitrile (3)
BSA
SV
Synthesis and purification were as outlined for com-
and k
is given by Eq. (5):
pound
1 except 3-nitrophthalonitrile was employed instead
BSA
K
of 4-nitrophthalonitrile. The amounts of the reagents
employed were: 3-nitrophthalonitrile (0.5 g, 2.89 mmol), 2-
[2-(dimethylamino)ethoxy]ethanol (1.15 g, 8.67 mmol), K2CO3
(3.98 g, 28.9 mmol) in anhydrous DMF (25 mL). Yield: 0.27 g
(36%), mp: 114–116 ◦C. IR (KBr pellet), ꢂmax/cm−1: 3087 (Ar–H),
2943–2868 (Aliph. C–H), 2229 (C N), 1583, 1472, 1355, 1295,
1181, 1130, 1063, 854, 796, 731, 689. 1H NMR. (CDCl3), (ı:ppm):
= kqꢀF(BSA)
(5)
SV
where F0BSA and FBSA are the fluorescence intensities of BSA in the
absence and presence of quaternized ZnPc complexes (2a and 4a),
respectively; KSBVSA, the Stern–Volmer quenching constant; kq, the
bimolecular quenching constant; and ꢀF(BSA), the fluorescence life-
time of BSA. ꢀF(BSA) is known to be 10 ns [51–53], thus from the

90
Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
Scheme 2. Synthesis of quaternized tetra-2-[2-(dimethylamino)ethoxy]ethanol substituted zinc phthalocyanine complexes.
7.60 (d, 1H, Ar–H), 7.30 (s, 1H, Ar–H), 7.25 (d, 1H, Ar–H), 4.24 (t,
2H, –CH2–O–Ar–), 3.84 (t, 2H, –CH2–O–), 3.59 (t, 2H, –CH2–O–),
2.43 (t, 2H, –CH2–N), 2.18 (s, 6H, CH3). 13C NMR. (CDCl3), (ı:ppm):
156.79, 130.36, 120.80, 118.76, 115.71, 112.96, 112.05, 100.06,
65.05, 64.826, 64.49, 54.05, 41.11. MS (ES+), (m/z): 260 [M+H]+.
2.5.4. 2(3),9(10),16(17),23(24)-Tetrakis{2-[2-
trimethylamino)ethoxy]ethoxy}phthalocyaninato zinc (II)iodide
(2a)
Compound 2 (40 mg, 0.036 mmol) was dissolved in 3.5 mL of
chloroform and methyl iodide (26 mg, 0.18 mmol) was added to this
solution. The reaction mixture was stirred under reflux for 3 h. After
cooling to room temperature, the green precipitate was filtered
off, washed with acetone, diethyl ether and chloroform and then
dried. Yield: 42 mg (70%). IR (KBr pellet) ꢂmax/cm−1: 3010 (Ar–H),
2917–2857 (Aliph. C–H), 1618, 1544, 1481, 1445, 1382, 1314, 1278,
1237, 1215, 1119, 1097, 1059, 952, 872, 743. MS (ES+), (m/z): 1655
[M−CH3]+.
2.5.3. 2(3),9(10),16(17),23(24)-Tetrakis{2-[2-
dimethylamino)ethoxy]ethoxy}phthalocyaninato zinc (II)
(2)
4-{2-[2-(Dimethylamino)ethoxy]ethoxy}phthalonitrile
(1)
(200 mg, 0.77 mmol), anhydrous Zn(CH3COO)2 (70 mg, 0.38 mmol)
and 2 mL of n-pentanol were placed in a standard Schlenk tube
in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
(0.48 mL, 0.31 mmol) under a nitrogen atmosphere and held at
reflux temperature for 16 h. After cooling to room temperature,
the reaction mixture was precipitated by adding it drop-wise into
diethylether. The crude product was collected by filtration and
washed with water, ethanol and ether and then dried. Purification
was achieved using column chromatography with basic alumina
as column material and CHCl3/MeOH (100:4) solvent system as
eluent. Yield: 63 mg (30%). IR (KBr pellet) ꢂmax/cm−1: 3065 (Ar–H),
2943–2868 (Aliph. C–H), 1607, 1488, 1448, 1393, 1359, 1315, 1242,
1123, 1091, 1057, 955, 841, 748, 635. 1H NMR (CDCl3), (ı:ppm):
7.49 (d, 4H, Ar–H), 6.98 (s, 4H, Ar–H), 6.86 (d, 4H, Ar–H), 3.97 (t, 8H,
–CH2–O–Ar–), 3.62 (t, 8H, –CH2–O–), 3.37 (t, 8H, –CH2–O–), 2.27
(t, 8H, –CH2–N), 2.01 (s, 24H, CH3). MS (ES+), (m/z): 1103 [M+H]+.
2.5.5. 1(4),8(11),15(18),22(25){2-[2-
dimethylamino)ethoxy]ethoxy}phthalocyaninato zinc (II)
(4)
Synthesis and purification were as outlined for compound 2
except
(3)
3-{2-[2-(dimethylamino)ethoxy]ethoxy}phthalonitrile
was
employed
instead
of
4-{2-[2-
(1). The
(dimethylamino)ethoxy]ethoxy}phthalonitrile
amounts of the reagents employed
were:
(3)
3-{2-[2-
(dimethylamino)ethoxy]ethoxy}phthalonitrile
(200 mg,
0.77 mmol), anhydrous Zn(CH3COO)2 (70 mg, 0.38 mmol), 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) (0.48 mL, 0.31 mmol) in
n-pentanol (2 mL). Yield: 59 mg (28%). IR (KBr pellet) ꢂmax/cm−1
:
3065 (Ar–H), 2930–2862 (Aliph. C–H), 1599, 1589, 1488, 1451,
1334, 1359, 1269, 1231, 1125, 1083, 885, 802, 745. 1H NMR

Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
91
Table 1
Absorption, excitation and emission spectral data for unsubstituted, non-peripheral and peripheral tetra-substituted zinc phthalocyanine complexes in DMSO and PBS.
Compound
Solvent
Q band ꢃmax (nm)
(log ␧)
Excitation ꢃEx (nm)
Emission ꢃEm (nm)
Stokes shift ꢁStokes (nm)
2
2a
DMSO
DMSO
PBS
PBS + TX
DMSO
DMSO
PBS
684
685
635, 688
686
706
705
654, 704
705
5.07
4.57
4.03, 3.88
4.29
5.03
4.95
4.42, 4.45
4.90
685
686
–
687
707
707
–
693
694
–
696
717
716
–
9
9
–
10
11
11
–
11
10
4
4a
PBS + TX
DMSO
706
672
716
682
ZnPca
672
5.14
a
Data from Ref. [21].
(CDCl3), (ı:ppm): 7.43 (m, 4H, Ar–H), 6.97 (s, 4H, Ar–H), 6.84 (d,
4H, Ar–H), 4.09 (m, 8H, –CH2–O–Ar–), 3.64 (m, 8H, –CH2–O–), 3.40
(t, 8H, –CH2–O–), 2.16 (m, 8H, –CH2–N), 2.01 (s, 24H, CH3). MS
(ES+), (m/z): 1125 [M+Na]+.
from the reaction of corresponding ZnPc complexes (2 and 4) with
methyl iodide as quaternization agent in chloroform. After reaction
with methyl iodide, the quaternized ZnPc complexes (2a and 4a) are
very soluble in water. The structures of the target compounds were
confirmed using IR, 1H NMR, 13C NMR and mass spectral data. All
the results were consistent with the predicted structures as shown
in the Section 2. The NMR spectra of the quaternarized phthalo-
cyanine complexes (2a and 4a) showed more unresolved patterns
compared to non-quaternarized derivatives due to the aggregation
of these complexes in deuterated DMSO.
2.5.6. 1(4),8(11),15(18),22(25)-Tetrakis{2-[2-
trimethylamino)ethoxy]ethoxy}phthalocyaninato zinc (II)iodide
(4a)
Synthesis and purification were as outlined for compound 2a
except compound 4 was employed instead of compound 2. The
amounts of the reagents employed were: compound 4 (40 mg,
0.036 mmol), methyl iodide (26 mg, 0.18 mmol) in chloroform
(3.5 mL). Yield: 40 mg (67%). IR (KBr pellet) ꢂmax/cm−1: 3005
(Ar–H), 2923–2862 (Aliph. C–H), 1613, 1589, 1486, 1382, 1322,
1267, 1231, 1168, 1113, 1065, 954, 883, 798, 744. MS (ES+), (m/z):
1543 [M−I]+.
3.2. Ground state electronic absorption spectra
The electronic absorption spectra of the studied ZnPc com-
plexes (2, 2a, 4 and 4a) showed characteristic absorptions in the
Q band region at around 684–706 nm in DMSO, Table 1. The B
bands were observed at around 350 nm (Fig. 1a). The spectra
showed monomeric behavior evidenced by a single (narrow) Q
band, typical of metallated phthalocyanine complexes in DMSO
[56]. The red-shifts were observed for ZnPc complexes follow-
3. Results and discussion
3.1. Synthesis and characterization
1.5
General synthetic route for the synthesis of new peripher-
ally and non-peripherally substituted ZnPc complexes (2 and
4) and their quaternized derivatives (2a and 4a) are given
a
4
2
1.2
4a
in Schemes
1 and 2, respectively. 2(3),9(10),16(17),23(24)-
2a
Tetrasubstituted (peripheral position) phthalocyanines can
be synthesized from 4-substituted phthalonitriles while
1(4),8(11),15(18),22(25)-tetrasubstituted (non-peripheral posi-
tion) phthalocyanines are obtained from 3-substituted analogues
[54]. In both cases, a mixture of four possible structural iso-
mers is obtained. The four probable isomers can be designed by
their molecular symmetry as C4h, C2v, Cs and D2h. In this study,
synthesized peripherally and non-peripherally substituted ZnPc
complexes are obtained as isomer mixtures as expected. No
attempt was made to separate the isomers of complexes.
0.9
2
2a
4
0.6
4a
0.3
0
300
400
500
600
700
800
Wavelength (nm)
0.4
Phthalonitrile derivatives (1 and 3) were synthesized
through base-catalyzed aromatic nitro displacement of
4-nitrophthalonitrile and 3-nitrophthalonitrile with 2-[2-
b
0.3
0.2
0.1
0
(dimethylamino)ethoxy]ethanol using K2CO3 as
a base in
anhydrous DMF. The reactions were carried out at 50 ◦C under N2
atmosphere for 72 h. The preparation of phthalocyanine deriva-
tives from the aromatic nitriles occurs under different reaction
conditions. For various substituted dinitriles, the reaction in
the presence of strong non-nucleophilic bases such as DBU or
1,5-diazabicyclo[4.3.0]non-5-ene (DBN) either in n-pentanol or in
bulk is most efficient in comparison to other methods. In addition,
these reactions are easy to perform, work under relatively mild
conditions and yield pure phthalocyanines [55].
4a
2a
300
400
500
600
700
800
Wavelength (nm)
Therefore, ZnPc complexes (2 and 4) were obtained by using the
anhydrous metal salt [Zn(CH3COO)2] in n-pentanol in the presence
of a strong organic base such as DBU at reflux temperature. Water
soluble tetra-cationic ZnPc complexes (2a and 4a) were obtained
Fig. 1. Absorption spectra of: (a) tetra-substituted zinc phthalocyanine complexes
(2, 2a, 4 and 4a) in DMSO, (b) cationic tetra-substituted zinc phthalocyanine com-
plexes (2a, and 4a) in PBS. Concentration = 1 × 10−5 M.

92
Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
1.4
1.2
1
Chloroform
Dichloromethane
Toluene
0.8
0.6
0.4
0.2
0
DMF
EtOH
300
400
500
600
700
800
Wavelength (nm)
Fig. 3. Absorption spectra of complex
tion = 1.0 × 10−5 M.
4 in different solvents. Concentra-
Fig. 2. Absorption spectral changes for complex 4a observed on addition of triton
X-100 (0.1 mL) in water. [4a] = 1 × 10−5 M.
Lambert law was obeyed for ZnPc complexes (2, 2a, 4 and 4a) in
the concentrations ranging from 1.2 × 10−5 to 2 × 10−6 M.
ing substitution. (For interpretation of the references to color in
this text, the reader is referred to the web version of the arti-
cle.) The Q bands of the non-peripherally substituted complexes
are red-shifted when compared to the corresponding peripherally
substituted complexes in DMSO (Fig. 1a). The red-shifts are 22 nm
between 2 and 4, 20 nm between 2a and 4a. The observed red spec-
tral shifts are typical of Pcs with substituents at the non-peripheral
positions and have been explained in the literature [57,58]. The B-
bands are broad due to the superimposition of the B1 and B2 bands
in the 350 nm region.
3.4. Fluorescence spectra
Fig. 5 shows fluorescence emission, absorption and excitation
spectra of complex 2 in DMSO as an example of the studied ZnPc
complexes. Fluorescence emission peaks were listed in Table 1. The
observed Stokes shifts were within the region observed for ZnPc
complexes. All studied ZnPc complexes (2, 2a, 4 and 4a) showed
similar fluorescence behavior in DMSO (Fig. 5 for complex 2 as an
example). The excitation spectra were similar to absorption spec-
tra and both were mirror images of the fluorescent spectra for
all ZnPc complexes in DMSO. The proximity of the wavelength of
each component of the Q-band absorption to the Q band maxima
of the excitation spectra for all ZnPc complexes suggests that the
nuclear configurations of the ground and excited states are simi-
lar and not affected by excitation. The water soluble quaternized
ZnPc complexes (2a and 4a) are non fluorescent in PBS due to
aggregation. Aggregated phthalocyanines are not known [20] to flu-
orescent since aggregation lowers the photoactivity of molecules
through dissipation of energy by aggregates. The addition of triton
X-100 increased the fluorescence emission of the studied fluores-
cent in PBS by lowering the aggregation, thus the quenching by the
aggregated species.
3.3. Aggregation studies
Aggregation is usually depicted as a coplanar association of rings
progressing from monomer to dimer and higher order complexes. It
is dependent on the concentration, nature of the solvent, nature of
the substituents, complexed metal ions and temperature [59,60].
In PBS, the absorption spectra of quaternized complexes (2a and
4a) showed cofacial aggregation (H-aggregation), as evidenced by
the presence of two non-vibrational peaks in the Q band region,
Fig. 1b. The lower energy (red-shifted) bands at 688 for 2a and
704 for 4a are due to the monomeric species, while the higher
energy (blue-shifted) bands at 635 for 2a and 654 nm for 4a are
due to the aggregated species. The peripherally substituted cationic
complex (2a) more aggregated than non-peripherally substituted
complex (4a) in PBS, suggesting that more sterically hinderence of
the substitution on the non-peripheral position.
Addition of triton X-100 (0.1 mL) to a PBS solution of quaternized
ZnPc complexes (2a and 4a) (concentration = 1.0 × 10−5) brought
about considerable increase in intensity of the low energy side of
the Q band (Fig. 2 as an example for complex 4a), suggesting that the
molecules are aggregated and that addition of triton X-100 breaks
up the aggregates between the Pc molecules.
In this study, the aggregation behavior of the ZnPc complexes
(2, 2a, 4 and 4a) were investigated in different solvents (Fig. 3 as
an example for complex 4). The non-ionic complexes (2 and 4) did
not aggregate in CHCl3, CH2Cl2, DMSO, DMF, toluene and ethanol.
The ionic complexes (2a and 4a) did not also aggregate in DMSO,
DMF and ethanol. The aggregation behavior of the studied ZnPc
complexes (2, 2a, 4 and 4a) were also studied at different concen-
tration in DMSO. In DMSO, as the concentration was increased, the
intensity of absorption of the Q band also increased and there were
no new bands (normally blue shifted) due to the aggregated species
for the ZnPc complexes (2, 2a, 4 and 4a) (Fig. 4 as an example for
complex 4). (For interpretation of the references to color in this
text, the reader is referred to the web version of the article.) Beer-
1.6
A
A
1.2
B
C
D
E
F
0.8
F
0.4
0
300
400
500
600
700
800
Wavelength (nm)
Fig. 4. Absorption spectral changes for 4 in DMSO at different concentrations:
12 × 10−6 (A), 10 × 10−6 (B), 8 × 10−6 (C), 6 × 10−6 (D), 4 × 10−6 (E), 2 × 10−6 (F) M.

Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
93
800
600
400
200
0
0.2
non-peripherally substituted ZnPc complex (4a) is higher than
peripherally substituted complex (2a), suggesting that the non-
peripherally substituted complex shows less aggregation than
peripherally substituted complex in this solution. The non-ionic
ZnPc complexes (2 and 4) show higher ˚F values compared to the
corresponding quaternarized ionic complexes (2a and 4a) in DMSO.
Fluorescence lifetime (ꢀF) refers to the average time a molecule
stays in its excited state before fluorescing, and its value is directly
related to that of ˚F; i.e., the longer the lifetime, the higher the
quantum yield of fluorescence. Any factor that shortens the fluo-
rescence lifetime of a compound indirectly reduces the value of ˚F.
Such factors include internal conversion and intersystem crossing.
As a result, the nature and the environment of a compound deter-
mine its fluorescence lifetime. ꢀF values were calculated using the
Strickler–Berg equation and these values are given in Table 2. The ꢀF
values of the substituted ZnPc complexes (2, 2a, 4 and 4a) are higher
compared to unsubstituted ZnPc complex in DMSO. ꢀF values are
lower for non-peripheral complexes (4 and 4a) when compared
to peripheral complexes (2 and 2a), Table 2, suggesting more
quenching by peripheral substitution compared to non-peripheral
substitution. However the ꢀF values are typical for ZnPc complexes
[20] in DMSO. The natural radiative lifetime (ꢀ0) and the rate con-
stants for fluorescence (kF) values are also given in Table 2. In DMSO,
ꢀ0 values of the substituted ZnPc complexes are higher, but the
kF values are lower than unsubstituted ZnPc complex. While the
quaternization of the ZnPc complexes caused to increasing of the
ꢀ0 values, decreasing of the kF values in DMSO.
Excitation
a
0.16
0.12
0.08
0.04
0
Absorption
Emission
500
550
600
650
700
750
800
850
Wavelength (nm)
250
200
150
100
50
4a in DMSO
b
4a in PBS+triton X-100
4a in PBS
0
685
705
725
745
765
785
805
825
3.6. Singlet oxygen quantum yields
Wavelength (nm)
The amount of the singlet oxygen quantum yield (˚ꢁ) is an
indication of the potential of the compounds as photosensitizers
in photocatalytic applications such as PDT. The ˚ꢁ values were
determined using a chemical method (DPBF in DMSO and ADMA
in both PBS and PBS + triton X-100 solutions). The disappearance
of DPBF or ADMA was monitored using UV-vis spectrophotome-
ter (Fig. 6a using DPBF for complex 2a in DMSO and Fig. 6b using
ADMA for complex 4a in PBS + triton X-100 solution). Many fac-
tors are responsible for the magnitude of the determined quantum
yield of singlet oxygen including; triplet excited state energy, abil-
ity of substituents and solvents to quench the singlet oxygen, the
triplet excited state lifetime and the efficiency of the energy trans-
fer between the triplet excited state and the ground state of oxygen.
There was no decrease in the Q band of formation of new bands dur-
ing ˚ꢁ determinations (Fig. 6). ˚ꢁ values of the ZnPc complexes
are given in Table 2 and it shows that the ˚ꢁ values are higher for
substituted ZnPc complexes (2, 2a, 4 and 4a) when compared to
respective unsubstituted ZnPc complex in DMSO. The ˚ꢁ values
of non-peripherally substituted complexes (4 and 4a) are higher
when compared to the peripherally substituted complexes (2 and
2a) in all studied solutions, suggesting that the non-peripherally
Fig. 5. (a) Absorption, excitation and emission spectra of 2 in DMSO (excitation
wavelengths: 650 nm), (b) emission spectra of 4a in DMSO, PBS and PBS + triton
X-100 (excitation wavelengths: 675 nm).
3.5. Fluorescence quantum yields and lifetimes
The fluorescence quantum yields (˚F) for non-ionic ZnPc com-
plexes (2 and 4) in DMSO and for quaternized ionic ZnPc complexes
(2a and 4a) in DMSO, PBS and PBS + triton X-100 are given in Table 2.
The ˚F values of all studied ZnPc complexes are typical of zinc
phthalocyanine complexes [20] in DMSO. The ˚F values of the
substituted ZnPc complexes (2, 2a, 4 and 4a) are lower compared
to unsubstituted ZnPc complex in DMSO, which implies that the
presence of the 2-[2-(dimethylamino)ethoxy]ethoxy substituents
certainly results in fluorescence quenching. The peripherally sub-
stituted complexes (2 and 2a) show higher ˚F values in DMSO,
compared to non-peripheral substituted complexes (4 and 4a),
suggesting not as much of quenching of the excited singlet state
by peripheral substitution compared to the non-peripheral sub-
stitution. In PBS + triton X-100 solution, the ˚F value of the
Table 2
Photophysical and photochemical parameters of unsubstituted, non-peripheral and peripheral tetra-substituted zinc phthalocyanine complexes in DMSO and PBS.
Compound
Solvent
˚
F
ꢀF (ns)
ꢀ0 (ns)
akF/108 (s−1
)
˚d/10−4
˚
ꢁ
2
2a
DMSO
DMSO
PBS
PBS + TX
DMSO
DMSO
PBS
0.19
0.15
–
0.04
0.11
0.10
–
1.94
4.36
–
2.47
1.42
1.44
–
10.23
28.86
–
61.71
12.97
14.47
–
0.98
0.34
–
0.16
0.77
0.69
–
1.21
0.20
0.73
23.43
0.82
1.92
0.25
36.64
0.26
0.77
0.73
0.05
0.34
0.88
0.79
0.13
0.44
0.67
4
4a
PBS + TX
DMSO
0.06
0.72
1.22
11.94
6.80
0.83
1.47
ZnPcb
0.20c
a
kF is the rate constant for fluorescence. Values calculated using kF = ˚F/ꢀF.
Data from Ref. [21].
Data from Ref. [42].
b
c

94
Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
1.2
1
0.8
0.6
0.4
0.2
0
a
0 sec
5 sec
10 sec
15 sec
20 sec
25 sec
1
0.8
0.6
0.4
0.2
0
0 sec
300 sec
600 sec
900 sec
300
400
500
600
700
800
300
400
500
600
700
800
Wavelength (nm)
Wavelength (nm)
1.2
1
Fig. 7. The photodegradation of 4 in DMSO showing the disappearance of the Q-band
at five minutes intervals.
b
in Fig. 7 (using complex 4 in DMSO as an example). The collapse of
the absorption spectra without any distortion of the shape confirms
clean photodegradation not associated with phototransformation
for complexes.
The photodegradation quantum yield (˚d) values of the ZnPc
complexes in DMSO, PBS and PBS + triton X-100 solutions are given
in Table 2. Stable phthalocyanine molecules show ˚d values as low
as 10−6 and for unstable molecules, values of the order of 10−3 have
been reported [20]. While all substituted ZnPc complexes (2, 2a, 4
and 4a) have an intermediate photostability in both DMSO and PBS,
they are less stable in PBS + triton X-100 solution. The quaterniza-
tion of the studied ZnPc complexes reduced to ˚d values and caused
to increasing of the stability of these complexes.
0 sec
0.8
0.6
0.4
0.2
0
300 sec
600 sec
900 sec
1200 sec
1500 sec
1800 sec
300
400
500
600
700
800
Wavelength (nm)
Fig. 6. A typical spectrum for the determination of singlet oxygen quantum yield
of: (a) 2a in DMSO using DPBF as a singlet oxygen quencher and (b) 4a in PBS + triton
X-100 using ADMA as a singlet oxygen quencher. Concentration = 1 × 10−5 M.
3.8. Interaction of quaternized cationic ZnPc complexes with BSA
substituted complexes absorb light at long wavelength. Table 2
shows that lower ˚ꢁ values are observed in aqueous solution com-
pared to in DMSO suggesting that aggregation of the ionic ZnPc
complexes this solution. The addition of the triton X-100 which is
a surfactan to aqueous solution breaks up the formed aggregates
between ionic ZnPc molecules in aqueous solution. However, the
ZnPc complexes (2a and 4a) have good ˚ꢁ values in PBS + triton
X-100 solution and these values make them as potential sensitiz-
ers for PDT applications. Quaternarized ionic ZnPc complexes (2a
and 4a) showed lower ˚ꢁ values when compared to corresponding
non-ionic complexes (2 and 4) in DMSO.
The fluorescence emission spectra of BSA in the presence of dif-
ferent concentrations of 4a in PBS show as an example in Fig. 8.
The quaternized ZnPc complexes are mixtures of aggregated and
unaggregated species. The total concentrations of the complexes
are mixture of the monomer and aggregated species. We calcu-
lated the percentage aggregation (% Agg) of these complexes using
the equation described in the literature [63,64]. The aggregation
percentages are 70% for 2a and 62% for 4a. The non-peripherally
substituted zinc phthalocyanine complex (4a) having lower % Agg
values which may be due to reduced aggregation tendencies when
the substitution is at the non-peripheral position of the Pc skeleton
[65].
3.7. Photodegradation studies
The BSA fluorescence at 348 nm is mainly attributable to tryp-
tophan residues in the macromolecule. BSA and the respective
Degradation of the molecules under light irradiation can be used
to study their stability and this is especially important for those
molecules intended for use in photocatalytic application such as
PDT. The collapse of the absorption spectra without any distortion
of the shape confirms clean photodegradation not associated with
phototransformation into different forms of MPc absorbing in the
visible region. Generally, photodegradation depends on the struc-
ture of the molecule, concentration, solvent and light intensity. It is
believed that photodegradation is a singlet oxygen mediated pro-
cess, since singlet oxygen is highly reactive and it can react with
phthalocyanines. For DPBF which is used as chemical quencher for
singlet oxygen a [4 + 2] cycloaddition with singlet oxygen under
formation of o-dibenzoylbenzene is known to occur [61]. A similar
reaction is supposed to occur between phthalocyanine derivatives
and singlet oxygen. In the case of phthalocyanines, phthalimide
residue was found to be the photooxidation product following
degradation [62].
800
A
600
400
G
200
0
290
340
390
440
490
Wavelength (nm)
Fig. 8. Fluorescence emission spectral changes of BSA (C = 3.00 × 10−5 M) on addi-
The spectral changes observed for all ZnPc complexes (2, 2a,
4 and 4a) in all studied solvents during irradiation are as shown
tion of varying concentrations of 4a in PBS. [4a]: A = 0, B = 1.66 × 10−6, C = 3.33 × 10−6
D = 5.00 × 10−6, E = 6.66 × 10−6, F = 8.33 × 10−6 M, G = saturated with 4a.
,

Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
95
1.8
1.6
1.4
1.2
1
interactions in aqueous solutions [49,67]. The higher Kb value
for quaternized non-peripherally substituted ZnPc complex (4a)
implies that a non-peripherally substituted ZnPc complex binds
more strongly to BSA than the quaternized peripherally substituted
ZnPc complex (2a), probably due to less aggregation tendencity
of the complex at the non-peripheral position. n values of near
unity suggest that both non-peripherally and peripherally substi-
tuted ZnPc complexes form 1:1 adducts with BSA. The decrease in
the intrinsic fluorescence intensity of tryptophan with quaternized
ZnPc concentration indicates that these complexes readily bind to
BSA, which implies that the phthalocyanine molecules reach sub-
domains where tryptophan residues are located in BSA. This also
suggests that the primary binding sites of these molecules are very
close to tryptophan residues, since the occurrence of quenching
requires molecular contact.
4a
2a
0
0.000001 0.000002 0.000003 0.000004 0.000005 0.000006 0.000007 0.000008 0.000009
[Pc]
Fig. 9. Stern–Volmer plots of tetra substituted zinc phthalocyanines quenching of
BSA in PBS. [BSA] = 3.00 × 10−5 M and [Pc] = 0, 1.66 × 10−6, 3.33 × 10−6, 5.00 × 10−6
,
6.66 × 10−6, 8.33 × 10−6 M in PBS.
4. Conclusion
Table 3
Binding and fluorescence quenching data for interaction of BSA with quaternized
zinc phthalocyanine complexes in PBS.
In conclusion, this work has described the synthesis, charac-
terization, aggregation behavior, photophysical and photochemical
properties of new non-peripherally and peripherally tetra-2-
[2-(dimethylamino)ethoxy]ethoxy substituted amphiphilic zinc
phthalocyanine photosensitizers to candidate for PDT. The effect of
quaternization on these properties is also presented. Solvent effect
(DMSO, PBS or PBS + triton X-100 solution) on the aggregation,
photophysical and photochemical properties of the quaternized
derivatives is investigated. Although, the photophysical and pho-
tochemical properties relevant for photosensitization gave more
attractive values in DMSO, the values in water are still enough for
PDT applications. Especially, the addition of triton X-100 to PBS
solution improved these properties due to lowering of aggregation.
This work will certainly enrich the hitherto scanty literature on the
potentials of amphiphilic zinc phthalocyanines as photosensitizers
in PDT. This study reveals that the water-soluble complexes bind
strongly to serum albumin; hence they can easily be transported in
the blood.
5
BSA
SV
Compound
K
/10 (M−1
)
kq/1013 (M−1 s−1
)
Kb/10−6 (M−1
)
n
2a
4a
0.64
0.86
0.86
0.86
4.26
5.28
1.22
1.04
quaternized cationic ZnPc complexes exhibit reciprocated fluo-
rescence quenching on one another; hence it was possible to
determine Stern–Volmer quenching constants (KSV). The slope of
the plots shown at Fig. 9 gave KSV values and listed in Table 3,
suggest that BSA fluorescence quenching is more effective for
quaternized non-peripherally substituted ZnPc complex (4a) than
quaternized peripherally substituted ZnPc complex (2a) in PBS.
Using the approximate fluorescence lifetime of BSA (10 ns) [52,53],
the bimolecular quenching constant (kq) was determined by Eq.
(5). These values are of the order of 1013
M
−1 s−1, which exceed the
proposed value of 1010 −1 s−1 for diffusion-controlled (dynamic)
M
quenching (according to the Einstein–Smoluchowski approxima-
tion) at room temperature [66]. This also, is an indication that
the mechanism of BSA quenching by quaternized ZnPc complexes
(2a and 4a) is not diffusion-controlled (i.e., not dynamic quench-
ing, but static quenching). The kq values are larger for quaternized
non-peripherally substituted ZnPc complex (4a) than quaternized
peripherally substituted ZnPc complex (2a) in PBS. The binding con-
stants (Kb) and number of binding sites (n) on BSA were obtained
using Eq. (5) and the results are shown in Table 3. The slope of the
plots shown at Fig. 10 gave n values and the intercepts of these
plots gave Kb values. The values of Kb and n are typical of MPc–BSA
Acknowledgement
This study was supported by the Research Fund of Karadeniz
Technical University (Project no: 2010.101.010.1).
References
[1] N.B. McKeown, Phthalocyanine Materials Synthesis. Structure and Function,
Cambridge University Press, 1998.
[2] K. Kadish, K.M. Smith, in: R. Guilard (Ed.), The Porphyrin Handbook, vols. 15–20,
Academic Press, Boston, 2003.
[3] I. Okura, Photosensitization of Porphyrins and Phthalocyanines, Gordon and
Breach Science Publishers, Amsterdam, 2000.
[4] G. Jori, Tumour photosensitizers: approaches to enhance the selectivity and
efficiency of photodynamic therapy, J. Photochem. Photobiol. B: Biol. 36 (1996)
87–93.
[5] M.P. De Dilippis, D. Dei, L. Fantetti, G. Roncucci, Synthesis of a new water-
soluble octa-cationic phthalocyanine derivative for PDT, Tetrahedron Lett. 41
(2000) 9143–9147.
[6] J. Marino, M.C.G. Vior, L.E. Dicelio, L.P. Roguin, J. Awruch, Photodynamic effects
of isosteric water-soluble phthalocyanines on human nasopharynx KB carci-
noma cells, Eur. J. Med. Chem. 45 (2010) 4129–4139.
0
4a
-0.2
2a
-0.4
-0.6
-0.8
-1
[7] K. Sakamoto, T. Kato, E. Ohno-Okumura, M. Watanabe, M.J. Cook, Synthesis of
novel cationic amphiphilic phthalocyanine derivatives for next generation pho-
tosensitizer using photodynamic therapy of cancer, Dyes Pigments 64 (2005)
63–71.
[8] M.J. Cook, I. Chambrier, S.J. Cracknell, D.A. Mayes, D.A. Russel, Octa-alkyl zinc
phthalocyanines: potential photosensitizers for use in the photodynamic ther-
apy of cancer, Photochem. Photobiol. 62 (1995) 542–545.
[9] P. Maillard, S. Gaspard, J.L. Guerquin-Kern, M. Momenteau, Glycoconjugated
tetrapyrrolic macrocycles, J. Am. Chem. Soc. 111 (1989) 9125–9127.
[10] C.-F. Choi, J.-D. Huang, P.-C. Lo, W.P. Fong, D.K.P. Ng, Glycosylated zinc(II)
phthalocyanines as efficient photosensitisers for photodynamic therapy.
Synthesis, photophysical properties and in vitro photodynamic activity, Org.
Biomol. Chem. 6 (2008) 2173–2181.
-1.2
-5.9
-5.8
-5.7
-5.6
-5.5
-5.4
-5.3
-5.2
-5.1
-5
log[Pc]
Fig. 10. Determination of quaternized zinc phthalocyanine–BSA binding constant
and number of binding sites on BSA. [BSA] = 3.00 × 10−5 M and [Pc] = 0, 1.66 × 10−6
,
3.33 × 10−6, 5.00 × 10−6, 6.66 × 10−6, 8.33 × 10−6 M in PBS.

96
Z. Bıyıklıog˘lu et al. / Journal of Photochemistry and Photobiology A: Chemistry 222 (2011) 87–96
[11] J. Moan, K. Berg, E. Kvam, A. Western, Z. Malik, A. Ruck, H. Schneckenburger,
in: G. Bock, S. Harnett (Eds.), Photosensitizing Compounds: Their Chemistry,
Biology and Clinical Use, John Wiley and Sons, New York, 1989, pp. 95–111.
[12] G. Jori, Photosensitized processes in vivo: proposed phototherapeutic applica-
tions, Photochem. Photobiol. 52 (1990) 439–443.
[13] T.J. Dougherty, A brief history of clinical photodynamic therapy development
at Roswell Park Cancer Institute, J. Clin. Laser Med. Surg. 14 (1996) 219–221.
[14] E. Ben-Hur, I. Rosenthal, Photosensitized inactivation of Chinese hamster cells
by phthalocyanines, Photochem. Photobiol. 42 (1985) 129–133.
[15] C.M. Allen, W.M. Sharman, J.E. van Lier, Current status of phthalocyanines in
the photodynamic therapy of cancer, J. Porphyrins Phthalocyanines 5 (2001)
161–169.
[40] S. Fery-Forgues, D. Lavabre, Are fluorescence quantum yields so tricky to mea-
sure? A demonstration using familiar stationery products, J. Chem. Educ. 76
(1999) 1260–1264.
[41] D. Maree, T. Nyokong, K. Suhling, D. Phillips, Effects of axial ligands on the
photophysical properties of silicon octaphenoxyphthalocyanine, J. Porphyrins
Phthalocyanines 6 (2002) 373–376.
[42] A. Ogunsipe, J.Y. Chen, T. Nyokong, Photophysical and photochemical studies of
zinc(II) phthalocyanine derivatives – effects of substituents and solvents, New
J. Chem. 28 (2004) 822–827.
[43] H. Du, R.A. Fuh, J. Li, A. Corkan, J.S. Lindsey, PhotochemCAD: a computer-aided
design and research tool in photochemistry, Photochem. Photobiol. 68 (1998)
141–142.
[16] H. Ali, J.E. van Lier, Metal complexes as photo- and radiosensitizers, Chem. Rev.
99 (1999) 2379–2450.
[44] J.H. Brannon, D. Madge, Picosecond laser photophysics. Group 3A phthalocya-
nines, J. Am. Chem. Soc. 102 (1980) 62–65.
[17] D. Phillips, The photochemistry of sensitisers for photodynamic therapy, Pure
Appl. Chem. 67 (1995) 117–126.
[18] R. Bonnett, Photosensitizers of the porphyrin and phthalocyanine series for
photodynamic therapy, Chem. Soc. Rev. 24 (1995) 19–33.
[19] A.C. Tedesco, J.C.G. Rotta, C.N. Lunardi, Synthesis, photophysical and photo-
chemical aspects of phthalocyanines for photodynamic therapy, Curr. Org.
Chem. 7 (2003) 187–196.
[45] A. Ogunsipe, T. Nyokong, Photophysical and photochemical studies of
sulphonated non-transition metal phthalocyanines in aqueous and non-
aqueous media, J. Photochem. Photobiol. A: Chem. 173 (2005) 211–220.
[46] N. Kuznetsova, N. Gretsova, E. Kalmkova, E. Makarova, S. Dashkevich, V. Neg-
rimovskii, O. Kaliya, E. Luk’yanets, Relationship between the photochemical
properties and structure of porphyrins and related compounds, Russ. J. Gen.
Chem. 70 (2000) 133–140.
[20] T. Nyokong, Effects of substituents on the photochemical and photophysical
properties of main group metal phthalocyanines, Coord. Chem. Rev. 251 (2007)
1707–1722.
[21] I. Gürol, M. Durmus¸ , V. Ahsen, T. Nyokong, Synthesis, photophysical and pho-
tochemical properties of substituted zinc phthalocyanines, Dalton Trans. 34
(2007) 3782–3791.
[47] W. Spiller, H. Kliesch, D. Wöhrle, S. Hackbarth, B. Roder, G. Schnurpfeil, Sin-
glet oxygen quantum yields of different photosensitizers in polar solvents and
micellar solutions, J. Porphyrins Phthalocyanines 2 (1998) 145–158.
[48] D.M. Chipman, V. Grisaro, N. Shanon, The binding of oligosaccharides contain-
ing n-acetylglucosamine and n-acetylmuramic acid to lysozyme: the specificity
of binding subsites, J. Biol. Chem. 242 (1967) 4388–4394.
[22] D. Atilla, N. Saydan, M. Durmus¸ , A.G. Gürek, T. Khan, A. Rück, H. Walt,
T. Nyokong, V. Ahsen, Synthesis and photodynamic potential of tetra- and
octa-triethyleneoxysulfonyl substituted zinc phthalocyanines, J. Photochem.
Photobiol. A: Chem. 186 (2007) 298–307.
[23] N. Saydan, M. Durmus¸ , M.G. Dizge, H. Yaman, A.G. Gürek, E. Antunes, T.
Nyokong, V. Ahsen, Water-soluble phthalocyanines mediated photodynamic
effect on mesothelioma cells, J. Porphyrins Phthalocyanines 13 (2009) 681–690.
[24] H.R.P. Karaog˘lu, A. Gül, M.B. Koc¸ ak, Synthesis and characterization of a new
tetracationic phthalocyanine, Dyes Pigments 76 (2008) 231–235.
[25] M. Durmus¸ , Z. Bıyıklıog˘lu, H. Kantekin, Synthesis, photophysical and photo-
chemical properties of crown ether substituted zinc phthalocyanines, Synth.
Met. 159 (2009) 1563–1571.
[26] H. Li, T.J. Jensen, F.R. Fronczek, M.G.H. Vicente, Syntheses and properties of
a series of cationic water-soluble phthalocyanines, J. Med. Chem. 51 (2008)
502–511.
[27] I. Scalise, E.N. Durantini, Synthesis, properties, and photodynamic inactivation
of Escherichia coli using a cationic and a noncharged Zn(II) pyridyloxyphthalo-
cyanine derivatives, Bioorg. Med. Chem. 13 (2005) 3037–3045.
[28] S. Wei, J. Zhou, D. Huang, X. Wang, B. Zhang, J. Shen, Synthesis and Type I/Type
II photosensitizing properties of a novel amphiphilic zinc phthalocyanine, Dyes
Pigments 71 (2006) 61–67.
[29] W. Duan, P. Lo, L. Duan, W.-P. Fong, D.K.P. Ng, Preparation and in vitro
photodynamic activity of amphiphilic zinc(II) phthalocyanines substituted
with 2-(dimethylamino)ethylthio moieties and their N-alkylated derivatives,
Bioorg. Med. Chem. 18 (2010) 2672–2677.
[30] K.E. Treacher, G.J. Clarkson, N.B. McKeown, Novel amphiphilic phthalocyanine
mesogens, Mol. Cryst. Liq. Cryst. 260 (1995) 255–260.
[31] P.-C. Lo, J.-D. Huang, D.Y.Y. Cheng, E.Y.M. Chan, W.-P. Fong, W.-H. Ko, D.K.P.
Ng, New amphiphilic silicon(IV) phthalocyanines as efficient photosensitizers
for photodynamic therapy: synthesis, photophysical properties, and in vitro
photodynamic activities, Chem. -A Eur. J. 10 (2004) 4831–4838.
[32] U. Kumru, M.A. Ermeydan, F. Dumoulin, V. Ahsen, Amphiphilic galactosylated
phthalocyanines, J. Porphyrins Phthalocyanines 12 (2008) 1090–1095.
[33] M.A. Ermeydan, F. Dumoulin, T.V. Basova, D. Bouchu, A.G. Gürek, V. Ahsen,
D. Lafont, Amphiphilic carbohydrate–phthalocyanine conjugates obtained by
glycosylation or by azide–alkyne click reaction, New J. Chem. 34 (2010)
1153–1162.
[49] S.M.T. Nunes, F.S. Sguilla, A.C. Tedesco, Photophysical studies of zinc phthalo-
cyanine and chloroaluminum phthalocyanine incorporated into liposomes in
the presence of additives, Braz. J. Med. Biol. Res. 37 (2004) 273–284.
[50] S. Lehrer, G.D. Fashman, The fluorescence of lysozyme and lysozyme substrate
complexes, Biochem. Biophys. Res. Commun. 23 (1966) 133–138.
[51] J.R. Lakowicz, G. Weber, Quenching of fluorescence by oxygen. Probe for struc-
tural fluctuations in macromolecules, Biochemistry 12 (1973) 4161–4170.
[52] C.Q. Jiang, M.X. Gao, J.X. He, Study of the interaction between terazosin and
serum albumin: synchronous fluorescence determination of terazosin, Anal.
Chim. Acta 452 (2002) 185–189.
[53] M. Gou, J.W. Zou, P.G. Yi, Z.C. Shang, G.X. Hu, Q.S. Yu, Binding interaction of
gatifloxacin with bovine serum albumin, Anal. Sci. 20 (2004) 465–470.
[54] C.C. Leznoff, in: C.C. Leznoff, A.B.P. Lever (Eds.), Phthalocyanines: Properties and
Applications, vol. 1, VCH Publishers, New York, 1989 (Chapter 1).
[55] F. Hacıveliog˘lu, M. Durmus¸ , S. Yes¸ ilot, A.G. Gürek, A. Kılıc¸ , V. Ahsen, The syn-
thesis, spectroscopic and thermal properties of phenoxycyclotriphosphazenyl-
substituted phthalocyanines, Dyes Pigments 79 (2008) 14–23.
[56] M.J. Stillman, T. Nyokong, in: C.C. Leznoff, A.B.P. Lever (Eds.), Phthalocyanines:
Properties and Applications, vol. 1, VCH Publishers, New York, 1989 (Chapter
3).
[57] A.B. Anderson, T.L. Gorden, M.E. Kenney, Electronic and redox properties of
stacked-ring silicon phthalocyanines from molecular orbital theory, J. Am.
Chem. Soc. 107 (1985) 192–195.
[58] M. Konami, M. Hatano, A. Tajiri, Inter-ring overlap integrals in dimer complexes
of phthalocyanines and porphyrins, Chem. Phys. Lett. 166 (1990) 605–608.
[59] H. Enkelkamp, R.J.M. Nolte, Molecular materials based on crown ether func-
tionalized phthalocyanines, J. Porphyrins Phthalocyanines 4 (2000) 454–459.
[60] D.D. Dominquez, A.W. Snow, J.S. Shirk, R.G.S. Pong, Polyethyleneoxide-capped
phthalocyanines: limiting phthalocyanine aggregation to dimer formation, J.
Porphyrins Phthalocyanines 5 (2001) 582–592.
[61] E.A. Lissi, M.V. Encinas, E. Lemp, M.A. Rubio, Singlet oxygen O2 (1ꢁg) bimolecu-
lar processes. Solvent and compartmentalization effects, Chem. Rev. 93v (1993)
699–723.
[62] G. Schnurpfeil, A.K. Sobbi, W. Spiller, H. Kliesch, D. Wöhrle, Photo-oxidative
stability and its correlation with semi-empirical MO calculations of various
tetraazaporphyrin derivatives in solution, J. Porphyrins Phthalocyanines 1
(1997) 159–167.
[34] M. Kimura, H. Ueki, K. Ohta, K. Hanabusa, H. Shirai, N. Kobayashi, Aggregation
behavior of amphiphilic phthalocyanine block copolymers, Langmuir 18 (2002)
7683–7687.
[35] D.C. Carter, J.X. Ho, Structure of serum albumin, Adv. Protein Chem. 45 (1994)
153–176.
[36] T. Peters, Serum albumin, Adv. Protein Chem. 37 (1985) 161–245.
[37] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory Chemicals, 2nd ed.,
Pegamon Press, Oxford, 1989.
[38] J.G. Young, W. Onyebuagu, Synthesis and characterization of di-disubstituted
phthalocyanines, J. Org. Chem. 55 (1990) 2155–2159.
[63] M. Idowu, T. Nyokong, Photophysical and photochemical properties of tetrasul-
fonated silicon and germanium phthalocyanine in aqueous and non-aqueous
media, J. Photochem. Photobiol. A: Chem. 197 (2008) 273–280.
[64] S. Khene, A. Ogunsipe, E. Antunes, T. Nyokong, Microwave synthesis and
photophysics of new tetrasulfonated tin(II) macrocycles, J. Porphyrins Phthalo-
cyanines 11 (2007) 109–117.
[65] R.D. George, A.W. Snow, J.S. Shirk, W.R. Barger, The alpha substitution effect on
phthalocyanine aggregation, J. Porphyrins Phthalocyanines 2 (1998) 1–7.
[66] S.L. Murov, I. Carmichael, G.L. Hug, Handbook of Photochemistry, 2nd ed., M.
Decker, New York, 1993.
[39] R.D. George, A.W. Snow, Synthesis of 3-nitrophthalonitrile and tetra-␣-
substituted phthalocyanines, J. Heterocycl. Chem. 32 (1995) 495–498.
[67] R. Nilsson, D.R. Kearns, Role of singlet oxygen in some chemiluminescence and
enzyme oxidation reactions, J. Phys. Chem. 78 (1974) 1681–1683.