The synthesis, photochemical and biological properties of new silicon phthalocyanines

Article abstract of DOI:10.1016/j.ica.2012.08.004

Bis[(1-methylpyrrolidin-2-yl)methoxy] [phthalocyaninato] silicon (2), bis[2-azepan-1-yl)ethoxy] [phthalocyaninato] silicon (3) and bis[(2,4,6-tris(N,N-dimethylamminomethyl) phenoxy)] [phthalocyaninato] silicon (4) were prepared and they were quaternized w

Full text of DOI:10.1016/j.ica.2012.08.004

Inorganica Chimica Acta 394 (2013) 353–362
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
The synthesis, photochemical and biological properties of new
silicon phthalocyanines
⇑
Canan Uslan, B. Sßebnem Sesalan
Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, Maslak 34469, Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 March 2012
Received in revised form 21 June 2012
Accepted 11 August 2012
Available online 23 August 2012
Bis[(1-methylpyrrolidin-2-yl)methoxy] [phthalocyaninato] silicon (2), bis[2-azepan-1-yl)ethoxy] [phtha-
locyaninato] silicon (3) and bis[(2,4,6-tris(N,N-dimethylamminomethyl) phenoxy)] [phthalocyaninato]
silicon (4) were prepared and they were quaternized with the excess of iodomethane to obtain the com-
pounds 2Q, 3Q and 4Q respectively. The binding of quaternized 2Q, 3Q and 4Q phthalocyanines (pcs)
with calf thymus (CT) DNA was investigated by UV–Vis, fluorescence spectrophotometric methods and
gel electrophoresis. The quenching effect of all quaternized pcs on the fluorescence intensity of SYBR Gold
(SYBR)–DNA complex was determined. The results indicated that novel pcs exhibit efficient DNA binding
activity. Photocleavage of CT-DNA in the presence of 2Q, 3Q and 4Q were determined using gel electro-
phoresis. All the experimental data proved that these pcs might be the candidates as DNA-targetting PDT
agents.
Keywords:
Silicon phthalocyanine
DNA
Fluorescence
Quaternization
Photocleavage of DNA
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
peripheral substituents play an important role in the photophysical
properties of pcs. A silicon phthalocyanine (pc), Pc 4, has attracted
DNA plays an increasingly important role in bioorganic chemis-
try, biotechnology, and material science. Owing to the central role
of DNA in replication and transcription, it has been a major target
for antibiotic, anticancer, and antiviral drugs [1]. The effects of nu-
cleic acid binding drugs are known for various diseases such as
cancer, malaria, AIDS, and other viral, bacterial, and fungal infec-
tions [2]. Since physicochemical properties of phthalocyanines
(pcs) can be easily adjusted by modification of the electronic distri-
bution on the aromatic ring through peripheral substitutions, they
have been studied as dyes [3], light emitting diodes, in molecular
electronics, for non-linear optical applications, as liquid crystals,
gas sensors, semiconductor materials, in photovoltaic cells and
for electrochromic displays [4–6]. In addition, they can be used
in immunohistochemistry, imaging the retinal veins and cardio-
vascular system as well as photodynamic therapy (PDT) of cancer
and photoinactivation of bacteria [7–9]. Pcs have a long-wave-
considerable interest as a PDT agent since it was reported to be
used in PDT in 1993 [15–19]. Si(IV)-Pcs containing one or two
bulky axial ligands usually show reduced aggregation, enhanced
water solubility, and high photodynamic efficacy. Recently, two
glucosylated Si(IV)-Pcs were shown to have high phototoxicity to-
ward human carcinoma HT29 and HepG2 cells [10] and a Si(IV)-Pc
bearing two solketal axial substituents was found to be highly pho-
totoxic to both 14C and B16F10 cell lines [20].
The interaction of silicon pcs with DNA, photoinactivation of
HIV and combination of them with platin units were reported as
efficient DNA-targeted PDT agents [21,22]. The peripheral substit-
uents and axial ligands govern to an important extent the physical,
chemical and biological properties of these compounds and make
it possible to prepare satisfactorily optimized pcs for use as
photosensitizers.
Among the different pcs employed for DNA binding studies, the
positively charged pcs are the most efficient ones in terms of bind-
ing and cleaving DNA as compared with either the neutral or neg-
atively charged pcs. In this perspective, the main scope of this work
is to synthesize new silicon pcs (Fig. 1) which have the potential
use for cancer treatment. We work on the synthesis of pcs and por-
phyrazines with different functional moieties such as heterocyclic
groups, porphyrazine–phthalocyanine hybrid units and quatern-
ized amino groups [23–30].
length band with a large extinction coefficient (ꢀ105 Mꢁ1 cmꢁ1
)
and generally a low dark toxicity. Some are efficient 1O2 generators
[6,10–13]. The ability of phthalocyanines to photoinactivate mam-
malian cells was reported first by Ben-Hur and Rosenthal in 1985
[14].
Of particular interest are positively charged pcs, since such mol-
ecules could potentially target highly vulnerable intracellular sites
and cause effective DNA photodamage. The central metal ion and
To clarify the binding mode of novel pcs (Fig. 2) to CT-DNA,
UV–Vis and fluorescence titration experiments, DNA gel electro-
phoresis were performed and the changes in CT-DNA thermal
⇑
Corresponding author. Tel.: +90 212 285 33 03; fax: +90 212 285 63 86.
E-mail address: sungurs@itu.edu.tr (B. Sßebnem Sesalan).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.08.004

354
C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
Cl
Melting temperature study was carried out using a thermo-
R
N
N
stated Shimadzu-1901 UV–Vis spectrophotometer.
Fluorescence and UV–Vis spectra were recorded on a Perkin-
Elmer LS55 fluorescence and Scinso SD 1000 spectrophotometer,
respectively.
(i)
N
N
N
N
N
N
N
N
Si
N
N
Si
N
N
N
N
Cl
R
Ha
H3e
C
1
Ha
2.3. Determination of binding of 2Q, 3Q and 4Q to DNA using UV–Vis
titrations
Hd
Hd
N
O Hb
2 R=
All titrations of pcs with CT-DNA were performed at room tem-
perature in distilled water. The concentrations of CT-DNA per
nucleotide phosphate ([DNA]) was calculated from the absorbance
Hc
Hc
Hc
Hc
at 260 nm using e
DNA = 6600 Mꢁ1 cmꢁ1[31]. DNA was stored at 4 °C
Hd
Hd
Hc
Hc
Hd
Hd
Hd
overnight and used within 2 days. 0.62 mM DNA, 0.04 mM 2Q, 3Q
and 4Q stock solutions were prepared in distilled water. A 1.5 mL
aqueous solution of 2Q, 3Q or 4Q was placed in 3 mL quartz cuv-
Ha Ha
O
3 R=
N
Hd
Hd
ette ( a final concentration of 3.6
lM) and 10 x 10 lL injections
Hb
of DNA were added manually. Absorption spectra were collected
from 300 to 800 nm. The titrations were carried out until pcs’ Q
bands remain at a fixed wavelength upon the successive additions
of CT-DNA.
Hb
Hd
Hc
Hc
H3aC
CH3a
N
Hc
Hb
Hb
O
CH3d
N
CH3d
2.4. Determination of binding 2Q, 3Q and 4Q to DNA using
fluorescence measurements
4 R=
He
He
Hb
Hb
Hc
The binding of water soluble complexes 2Q, 3Q and 4Q to DNA
were studied by spectrofluorometry at room temperature. An
N
CH3a
H3a
C
aqueous solution of 2Q, 3Q or 4Q (1
successive additions of 5 L aliquots of 5
tion of DNA, the fluorescence emission spectra were recorded. The
concentration of DNA along the titration varied from to
0.059 M. Fluorescence excitation and emission spectra were ob-
l
M, 2.5 mL) was titrated by
l
lM DNA. After each addi-
Fig. 1. The synthetic pathway of the compounds 2, 3 and 4. (i) Dry toluene, NaH,
6 h, reflux.
0
l
denaturation profiles were determined. Furthermore, quenching
effect of novel pcs on the fluorescence intensity of SYBR–DNA com-
plex with Stern–Volmer constants were calculated. Afterwards, we
studies the photo-induced DNA cleaving abilities of these
macrocycles.
tained from solutions of DNA and quaternized pcs (2Q–4Q) were
prepared in distilled water. Excitation and emission slits were set
at 7 nm bandpass at 900 V. Pcs solutions were excited at 610 nm
and spectra were recorded between 650 and 750 nm. The steady
diminution in pcs fluorescence with increase in DNA concentra-
tions was noted and used in the determination of the binding con-
stants and the number of binding sites on DNA, according to Eq. (3)
[32].
2. Experimental
2.1. Materials
nQ þ B $ Qn þ B
ð1Þ
All reagents and solvents were of reagent grade quality and
were obtained from commercial suppliers. 1-Methylpyrrolidin-2-
yl-methanol, 2-azepan-1-yl-ethanol, 2,4,6-tris(N,N-dimethylami-
nomethyl) phenol and dichloro [phthalocyaninato] silicon were
purchased from Aldrich. SYBR Gold was purchased from Fluka.
where B is biomolecule like pc (unbound or free form), Qn is
DNA with n binding sites. Here, Qn + B is the quenched biomole-
cule (pc when bound to DNA) whose association constant is Ka.
n
Ka ¼ ½Qn þ Bꢂ=ð½Qꢂ ½BꢂÞ
ð2Þ
If the overall amount of pcs is B0, then [B0] = [B] +[Qn + B]. Here
[B] is the concentration of the unbound pc. According to this data,
the relationship between the fluorescence and the unbound pc can
be defined as [B]/[B0] = F/F0 where F is the fluorescence of the un-
bound pc during the addition of DNA and F0 is the initial intensity
of pc
2.2. Equipment
1H NMR spectra were recorded on a Varian Mercury 200 MHz
spectrometer in CDCl3 and DMSO-d6. Chemical shifts were re-
ported (d) relative to Me4Si as internal standard.
Positive ion and linear mode MALDI-MS of complexes were ob-
tained in dihydroxybenzoic acid as MALDI matrix using nitrogen
laser accumulating 50 laser shots using Bruker Microflex LT MAL-
DI-TOF mass spectrometer.
IR spectra were recorded on a Perkin-Elmer Spectrum One FT-IR
spectrophotometer and electronic spectra on Scinco Neosys 2000
double beam UV–Vis Spectrophotometer with 1 cm path length
quartz cuvettes in the spectral range of 300–800 nm.
Elemental analyses were performed with Thermo Finnigan
Flash EA 1112 at 950–1000 °C.
logðF0 ꢁ FÞ=F ¼ logKa þ nlog½DNAꢂ
ð3Þ
where F0 and F are the fluorescence intensities of pc complex
(2Q, 3Q or 4Q) in the absence and presence of DNA respectively;
Ka, the binding constant; n, the number of binding sites on DNA;
and [DNA] the concentration of DNA solution. Plots of log[(F0–F)/
F] against log [DNA] would provide the values of n (from the slope)
and Ka (from the intercept). The experiments were repeated three
times and standard deviations were given in Table 1.

C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
355
n+
R
R
N
N
i)
N
N
N
N
N
N
N
N
nI-
N
N
Si
N
N
N
Si
N
R
R
CH3e
Ha
Ha
Hd
Hd
Hc
Hc
N
N
2
O
R =
O
2Q R=
Hb
Hc Hc
n=2
Hd
2Hc
2Hd
2Ha
2Hd
2Hd
3Q R=
O
N
O
3
R =
N
2Hb
H3c
C
Hd
2Hc
aH3C
H3a
CH3a
C
CH3d
N
He
N
CH3d
CH3d
2Hb
N
n=6
N
O
4 R =
4Q R=
O
2Hc
He
CH3a
CH3a
2Hb
aH3C
N
N
Fig. 2. The synthesis of quaternized phthalocyanines 2Q, 3Q and 4Q. (i) CH2Cl2, CH3I, 25 °C, 4 h.
at 900 V with a slit of 7 nm for both excitation and emission. All
solutions were prepared in distilled water.
Table 1
Ka, Ksv and n values of compounds with standard deviations ( STD) 2Q, 3Q and 4Q.
The quenching effect of quaternized pcs 2Q–4Q on the fluores-
cence of SYBR–DNA complex was calculated by using Stern–Vol-
mer relationship [33] according to Eq. (4):
2Q
3Q
4Q
Ka (ꢃ103) (L/mol)
7.048 0.8
1.35 0.7
0.61 0.8
5.370 0.7
0.794 0.8
0.52 0.7
2.089 0.8
0.473 0.8
0.56 0.8
Ksv (L/mol)
n
F0=F ¼ 1 þ Ks ½pcꢂ
ð4Þ
v
where F0 and F are the fluorescence intensities of the excited
DNA–SYBR complex in the absence and presence of pcs, [pc] is
the concentration of 2Q, 3Q or 4Q and KSV is the Stern–Volmer con-
stant. The slope of the plots of F0/F versus [pc] provide the value of
Ksv which indicates the affinity of quaternized pcs 2Q–4Q to DNA.
The measurements were repeated three times and standard devia-
tions were calculated.
2.5. Determination of quenching effect of 2Q, 3Q and 4Q on the
fluorescence intensity of DNA–SYBR complex by using Ksv constants
In order to determine the binding mode of 2Q–4Q pcs to DNA,
the decrease in emission of DNA-SYBR complex around 540 nm
was monitored indicating the competitive binding of SYBR with
quaternized pcs 2Q–4Q. The concentration of the purchased SYBR
Gold was 10000ꢃ and was diluted to 1ꢃ. Each of six fluorescence
cuvettes contained the solution of SYBR at a fixed concentration of
2.6. Determination of the change in thermal denaturation profile of
DNA
1ꢃ (200
l
L) and the solution of DNA (5
l
M, 1.8 mL). At a final con-
centration of 0, 0.1, 0.25, 0.5, 0.75 and 1
l
M, 200 L solutions of
l
Melting temperatures were determined for CT-DNA (0.062 mM,
2.5 mL) and 2Q, 3Q or 4Q (0.021 mM, 0.1 mL) in water by heating
from 25 to 90 °C at a rate of 0.6 °C/min, recording the UV absor-
bance at 260 nm every 10 s.
quaternized pcs 2Q–4Q were added to the solution of SYBR–DNA
complex in each cuvette. The samples were excited at 497 nm
and the spectra were recorded from 520 to 650 nm consecutively

356
C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
2.7. Determination of binding 2Q, 3Q and 4Q to DNA using gel
8.05–8.07 (m, 8H, Hb); 9.33–9.35 (m, 8H, Ha). Anal. Calc. for C44-
electrophoresis
H40N10O2Si: C, 69.10; H, 5.54; N, 17.39. Found: C, 68.73; H, 5.24;
N, 17.01%.
The binding of compounds 2Q–4Q to DNA was further studied
by gel electrophoresis. R refers to the ratio of [MPc]/[DNA].
2.7 lM DNA, 1 lM 2Q, 3Q and 4Q solutions were prepared in dis-
tilled water and used in ratio given in Table 1. Staining solution
was prepared in Tris/borate/EDTA (TBE). The products were run
at 120 V for 20 min 1% agarose gel, stained with SYBR and analyzed
photographically under UV light.
Data for compound 3: The crude product was subjected to alu-
minum oxide column chromatography and was purified by using
tetrahydrofuran/chloroform (10/1) as eluent (Fig. 1). Yield: 35 mg
(52.2%). IR m
max/(cmꢁ1): 3011; 2907; 1613; 1520; 1426; 1332;
1288; 1164; 1121; 1077; 1050; 1004; 952; 909; 758. 1H NMR (ace-
tone-d6): ꢁ1.92–(ꢁ1.89) (t, 4H, Ha), 0.30–0.34 (t,4H,Hb); 1.71–1.83
(m,16H,Hd); 3.45–3.51 (m, 8H, Hc); 8.35–8.42 (m, 8H, Hb); 9.58–
9.62 (m, 8H, Ha). Mass (MALDI-TOFF): m/z calculated for C48H48-
2.8. Determination of singlet oxygen generation of 2Q, 3Q and 4Q
N10O2Si [M]+: 825.05; found 825.48. Anal. Calc. for C48H48N10O2Si:
C, 69.80; H, 6.07; N, 16.90. Found:C, 69.88; H, 5.86; N, 16.98%.
Data for compound 4: Firstly, the oily residue was reacted with
tetrahydrofuran (30 mL) at room temperature 1 h. Then the mixture
was centrifuged and the impurities were precipitated and the fil-
trate was evaporated. Secondly the residue was dissolved in acetone
(30 mL) and the impurities were precipitated. The filtrate was evap-
orated under vacuum until it was dry. The crude product was then
washed with cold hexan (2 ꢃ 30 mL) and then cold diethyl ether
Photo-irradiations were done using a 600–700 nm diode laser.
A dichroic filter (Schimadzu) was additionally placed in the light
path before the sample. A 3 mL portion of the respective substi-
tuted pc derivatives; 2Q, 3Q and 4Q, (concentration = 1 ꢃ 10ꢁ5 M)
containing the singlet oxygen quencher was irradiated in the Q
band region with the photo-irradiation set-up described in refer-
ences [34,35]. 9,10-Antracenediyl-bis(methylene)dimalonoic acid
(ADMA) was used as chemical quencher for singlet oxygen in aque-
ous media. To avoid chain reactions induced ADMA in the presence
of singlet oxygen [36], the concentration of ADMA was lowered to
ꢀ3 ꢃ 10ꢁ5 M. Solutions of sensitizer containing ADMA were pre-
pared in the dark and irradiated in the Q band region using the set-
up described above. ADMA degradation at 380 nm (in water) was
monitored. Spectra were recorded every 5 s.
(3 ꢃ 30 mL) (Fig. 1). Yield: 31 mg (35.6%). IR
m
max/(cmꢁ1): 3011;
2942; 2855; 2815; 2771; 1606; 1357; 1313; 1247; 1173; 1144;
1097; 1025; 986; 880; 836. 1H NMR (DMSO-d6): 1.17–1.33 (m, 8H,
Hb); 2.22–2.03 (m, 24H, Ha); 2.23–2.32 (br s, 12H, Hc); 2.33–2.40
(br s, 4H, Hd); 6.91–6.98 (m,4H,He); 8.44–8.67 (m, 8H, Hb); 9.54–
9.77 (m, 8H, Ha). Mass (MALDI-TOFF): m/z calculated for C62H68N14-
O2Si [Mꢁ2]+: 1067.38; found 1067.48. Anal. Calc. for C62H68N14O2Si:
C, 69.60; H, 6.38; N, 18.30. Found: C, 69.63; H, 6.41; N, 18.29%.
2.9. Determination of photocleavage of plasmid DNA using gel
electrophoresis
2.10.2. The general route for the synthesis of quaternized bis[(1-methyl
pyrrolidin-2-yl)methoxy] [phthalocyaninato] silicon (2Q), bis[(2-
azepan-1-yl)ethoxy] [phthalocyaninato] silicon (3Q) and bis(2,4,6-tris
(N,N-dimethylamminomethyl) phenoxy) [phthalocyaninato] silicon
(4Q)
The experiments were performed in 0.5 mL plastic eppendorf
microcentrifuge tubes. Each tube contained 10
lL (0.2 lg) of
supercoiled DNA (pBR322) and 0.87 M 2Q, 3Q and 4Q solutions
l
were prepared in distilled water. Tubes were illuminated from
top and in air at room temperature with 600–700 nm diode laser
which was placed 5 cm away from the tested tubes. Irradiation
time changed from 1 to 5 s. without changing the concentrations
of the reactants in each tube. After irradiation, conversion of super-
coiled DNA (form I) to nicked circular DNA (form II) was visualized
by 1% agarose gel electrophoresis and subsequent SYBR staining.
To test the involvement of singlet oxygen in photocleavage,
The quaternization of neutral compounds 2, 3 and 4 was pre-
pared according to the previous work [25]. Briefly, the compound
2, 3 or 4 (100 mg, 0.13 mmol) was dissolved in CH2Cl2 (30 cm3)
and stirred with excess CH3I (185 mg, 1.56 mmol) at room temper-
ature for 4 h. The mixture was then filtered and the precipitate was
washed with CH2Cl2 (5 ꢃ 30 mL) and dried in vacuo.
Data for the compound 2Q: Yield: 72 mg (52.9%). IR mmax
/
0.2 M (5
l
L) sodium azide was used.
(cmꢁ1): 2883; 1976; 1610; 1521; 1472; 1429; 1335; 1292; 1166;
1114; 1080; 957; 910; 791; 757. 1H NMR (DMSO-d6): ꢁ2.30-
(ꢁ2.22) (d, 4H, Ha); ꢁ1.81-(ꢁ1.77) (m, 2H, Hb); 1.65–1.87 (m,
8H, Hc); 2.25–2.33 (m, 4H, Hd); 3.06 (s, 12H, He); 8.28–8.34 (m,
2.10. Synthesis
2.10.1. The general route for the synthesis of bis[(1-methylpyrrolidin-
2-yl)methoxy] [phthalocyaninato] silicon (2), bis[2-azepan-1-yl)ethoxy]
[phthalocyaninato] silicon (3) and bis(2,4,6-tris(N,N-dimethylammino-
methyl) phenoxy) [phthalocyaninato] silicon (4)
8H, Hb); 9.45–9.51 (m, 8H, Ha) (Fig. 2). Mass (MALDI-TOFF): m/z
calculated for C46H46N10O2Si2+ [Mꢁ2I+1]+: 800.01; found 800.08.
Anal. Calc. for C46H46N10I2Si: C, 52.50; H, 4.38; N: 13.28. Found:
C, 52.48; H, 4.40; N, 13.30%.
A mixture of unsubstituted dichloro [phthalocyaninato] silicon
(1) (50 mg, 0.0817 mmol), NaH (0.735 mmol, 17.6 mg) and
(1-methylpyrrolidin-2-yl)methanol (28.21 mg, 0.245 mmol) for
compound 2, 2-(azepan-1-yl)ethanol (35.08 mg, 0.245 mmol) for
Data for the compound 3Q: Yield: 62 mg (46.3%). IR mmax/
(cmꢁ1): 2851; 2579; 1974; 1610; 1519; 1472; 1428; 1335; 1291;
1162; 1121; 1078; 998; 947; 909; 852; 790; 758; 717. 1H NMR
(DMSO-d6): ꢁ2.16-(ꢁ2.05) (t, 4H, Ha); 0.50–0.54 (t, 4H, Hb);
2.23–2.09 (m, 16H, Hd); 2.81–2.90 (m, 14H, Hc); 8.16–8.22 (m,
compound
3 or 2,4,6-tris(N,N-dimethylaminomethyl) phenol
(65 mg, 0.245 mmol) for compound 4 in dry toluene (25 mL) was
refluxed for 6 h under N2. After the reaction mixture was centri-
fuged, the filtrate was evaporated and the residue was washed
with n-hexane (3 ꢃ 30 mL) and dried in vacuo.
8H, Hb); 9.32–9.34 (m, 8H, Ha) (Fig. 2). Mass (MALDI-TOFF): m/z
calculated for C50H54N10O2Si2+ [Mꢁ2I+1]+: 856.11; found 856.07.
Anal. Calc. for C50H54N10I2Si: C, 54.18; H, 4.89; N, 12.60. Found: C,
54.15; H, 4.91; N, 12.63%.
Data for compound 2: The crude product was subjected to alu-
minum oxide column chromatography and was purified by using
dichloromethane/methanol (10/1) as eluent (Fig. 1). Yield: 38 mg
Data for the compound 4Q: Yield: 50 mg (27.9%). IR mmax/
(cmꢁ1): 3012; 2943; 1608; 1478; 1377; 1337; 1250, 1163; 1124;
1082; 1011; 973; 911; 870; 777. 1H NMR (D2O): 1.67–1.93 (br s,
8H, Hb); 2.59–2.92 (br s, 36H, Ha); 2.94–2.97 (s, 4H, Hc); 2.98–
3.22 (s, 18H, Hd); 7.73–8.00 (m, 4H, He); 8.02–8.69 (s, 8H, Hb);
(61.2%). IR
m
max/(cmꢁ1): 2773; 1611; 1519; 1471; 1426; 1333;
1287; 1163; 1119; 1076; 985; 908; 757. 1H NMR (CDCl3):
ꢁ2.29–(ꢁ1.85) (d, 4H, Ha); (ꢁ0.54)-(ꢁ0.77) (m, 2H, Hb); 1.26–
1.27 (m, 8H, Hc); 1.62–2.07 (t, 4H, Hd); 2.08–3.20 (s, 4H, He);
9.23–10.00 (m, 8H, Ha) (Fig. 2). Mass (MALDI-TOFF): m/z calcu-
lated for C65H77N14O2Si3+[Mꢁ6Iꢁ3CH3]+: 1114.48; found 1114.21.

C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
357
Anal. Calc. for C68H86N14I6Si: C, 42.50; H, 4.49; N, 10.18. Found: C,
42.52; H, 4.51; N, 10.21%.
of compound 3Q showed the base peak cleavage of anion as is often
observed for this type of compounds [38]. Cationic molecular ion
peak; [Mꢁ2I+1]+, was seen at 856.07 and was harmonized with cal-
culated value.
3. Results and discussion
For compound 4, in IR spectrum vibration at 1097 cmꢁ1 showed
Si–O bond. In 1H NMR spectrum of 4, shifts between 1.17–
1.33 ppm for b protons and 2.22–2.03 ppm for a protons indicated
magnetic anisotropy of the pc ring [39]. According to integral areas,
p-N–CH3 protons (c) and p-N–CH2 protons (d) were shown be-
tween 2.23–2.32 ppm and 2.33–2.40 ppm, respectively. Aromatic
protons were seen between 6.91–6.98 ppm. b protons between
3.1. Synthesis
The synthetic procedures of the pc complexes 2–4 and 2Q–4Q
were given in Figs. 1 and 2. New silicon pcs were prepared in the
presence of NaH for deprotonation of alcohol derivatives or phenol.
While the compound 1 was insoluble in toluene, the new products
2, 3 and 4 were soluble. Excess of iodomethane was used in order
to obtain complete quaternization. For the characterization of com-
pounds 1H NMR, IR, mass spectra and elemental analysis results
were used. All reactions were followed by TLC (thin layer chroma-
tography) and the compounds 2 and 3 were purified with column
chromatography. Since the compound 4 was basic due to the
amine groups, purification with chromatographic methods (it
was adsorbed even on basic alumina) were unsuccessful. However,
elemental analysis results of all compounds were in accordance
with the calculated ones.
8.44–8.67 ppm and
a protons were observed between 9.54–
9.77 ppm (Fig. 1). In mass spectrum [Mꢁ2]+ peak was observed
at 1067.48 m/z. Elemental analysis results supported the expected
structure.
In IR spectrum of 4Q, vibrations at 3012 cmꢁ1 supported the
existence of aromatic structure and vibrations at 1082 cmꢁ1 indi-
cated the formation of Si–O bond. In 1H NMR spectrum, due to
shielding effect of pc ring, the shifts between 2.59–2.92 ppm and
1.67–1.93 ppm were attributed to a and b protons respectively.
According to integral areas, c and d protons were seen between
2.94–2.97 ppm and 2.98–3.22 ppm respectively. Aromatic protons
(e) protons were shown around 7.73 ppm. b protons between
For the compound 2, vibrations at 1076 cmꢁ1 indicated Si–O
bond in IR spectrum. Around 1076 cmꢁ1 Si–O vibrations were ob-
served in IR spectrum. In 1H NMR spectrum, due to magnetic anisot-
ropy [37], a and b protons were observed between ꢁ2.29–
(ꢁ1.65) ppm as dublet and (ꢁ0.54)–(ꢁ0.77) ppm as multiplet,
respectively. C protons were seen between 1.26 and 1.27 ppm.
The shifts between 1.62–2.07 ppm and 3.20–2.08 ppm were attrib-
uted to N–CH2 (d) protons and N–CH3 (e) protons respectively. The
8.02–8.69 ppm and
a protons were observed between 9.23–
10.00 ppm (Fig. 2). MALDI-TOFF mass spectrum of 4Q showed
the base peak cleavage of anion and methyl as is often observed
for this type of compounds [38].
3.2. Determination of binding of 2Q, 3Q and 4Q to DNA using UV–Vis
measurements
characteristic
a and b protons of pc macrocycle were seen between
9.33–9.35 ppm and 8.05–8.07 ppm, respectively (Fig. 1). Molecular
ion peak of 2 was not observed in MALDI-TOFF spectrum. However
elemental analysis results were consistent with the calculated ones.
In IR spectrum of 2Q, vibrations at 1080 cmꢁ1 were proved the
presence of Si–O bond. In 1H NMR spectrum, e protons which were
attributed to hydrogens of methyl groups attached to nitrogen
were observed at 3.06 ppm as singlet. A and b protons were
observed between ꢁ2.30–(ꢁ2,22) ppm and between ꢁ1.81–
(ꢁ1.77) ppm, respectively. Magnetic anisotropy was effective for
a and b protons which were close to Si–O bond indicating the
shielding effect of pc macrocycle [37]. The shifts between 1.65–
1.87 ppm were attributed to c protons. N–CH2 (d) protons were ob-
served between 2.25–2.33 ppm. The shifts between 8.28–8.34 ppm
While DNA intercalating agents cause large shifts at wave-
lengths, groove binding or stacking are observed by small changes
in absorbances or wavelengths in the UV–Vis spectrum [31].
The more the increase in aggregation, the more the decrease in
maximum was observed. Thick black lines in Fig. 3 (lines from 9
to 11 in Fig. 3a and b and lines from 8 to 11 in Fig. 3c were overlap-
ping each other indicated that after addition of 80
lL CT-DNA to 2Q
and 3Q, 70 L CT-DNA to 4Q, the Q band absorbance remained con-
l
stant) showed the end of titration which means maximum interac-
tion between pcs and DNA occurred. According to Fig. 3a and b 2Q
and 3Q displayed neither blue nor red shift around Q-band (683 nm
for 2Q and 684 nm for 3Q) as well as in Soret band region. In case of
2Q and 3Q, the lack of shift in band maxima and a small hypocrom-
icity of quaternized pcs was consistent with simple electrostatic
binding between positive pc and negative phosphate backbone of
DNA and was due to small axial ligands substituted to pc ring inhib-
iting closer stacking [40]. There was no shift around Q band
(688 nm) region in UV–Vis spectrum of 4Q as well as 2Q and 3Q
while a red shift from 308 nm to 311 nm indicating an existance
of external binding [41] (Fig. 3c). As reported earlier [41], intercala-
tive binding displays a much larger spectral shift as well as hypo-
chromicity in the absorption spectrum than external monomeric
and 9.45–9.51 ppm indicated the characteristic b and
a protons in
pc ring, respectively (Fig 2). In mass spectrum of compound 2Q
showed the base peak cleavage of anion as is often observed for
this type of compounds [38].
For compound 3, in IR spectrum vibrations 1077 cmꢁ1 con-
firmed Si–O bond. In 1H NMR spectrum proved the presence of
shielding effect of pc molecule on a and b protons which were
substituted directly on the macrocyle with the shifts observed be-
tween ꢁ1.92–(ꢁ1.89) ppm and 0.30–0.34 ppm, respectively. D
protons were seen as multiplet between 1.71–1.83 ppm. The shifts
binding or outside stacking due to the
p–p interaction between
between 3.45–3.51 ppm were attributed to N–CH2 (c) protons.
a
pc plane and the DNA base pairs. When we compared the narrow
Q band of 2Q and 3Q with broad one of 4Q, aggregation due to
amine groups caused a broad and less intense Q band as shown in
Fig. 3c. Upon the addition of DNA, the aggregation among bulky
quaternized amines in compound 4Q caused so small decrease in
absorbance around Q band region that hypochromicity was nondis-
tinguishable [42]. Since the phthalocyanines are macromolecules,
small or planar substituents may result intercalative binding. Here,
as proved with Ka values, the smallest cationic group (in 2Q) has
more affinity to interact with DNA more than 3Q and 4Q supporting
non-intercalative but minor groove binding. Axial groups in silicon
phthalocyanines also inhibit aggregation and promote minor
and protons of pc macrocycle were seen between 9.58–
b
9.62 ppm and 8.35–8.42 ppm, respectively (Fig 1). Molecular ion
peak; [M]+ at 825.48 was observed and supported the expected
structure together with elemental analysis results.
IR spectrum of compound 3Q supported the Si–O bond with the
vibrations at 1078 cmꢁ1. Further, 1H NMR spectrum of 3Q quatern-
ized methyl groups were observed at 2.81–2.90 ppm and d protons
between 2.23–2.09 ppm as multiplet. A and b protons were seen be-
tween ꢁ2.16–(ꢁ2.05) ppm and (ꢁ0.54)–(ꢁ0.77) ppm respectively.
Characteristic b and
a protons of pc ring were seen between 8.16–
8.22 ppm and 9.32–9.34 ppm respectively (Fig. 2). In mass spectrum

358
C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
(a)
(b)
(c)
Fig. 3. Electronic spectra of 2Q (a), 3Q (b) and 4Q (c) upon increasing amounts of CT-DNA. 10 successive injections (each contained 10
3.6 M, 1.5 mL aqueous solution of 2Q, 3Q or 4Q. Line 1: spectrum of the solution which contained 3.6 M, 1.5 mL of 2Q (a), 3Q (b) or 4Q (c). Line 2–8: The decrease in
absorbance continued (Line 2 (10 L) to line 8 (70 L)) until a stable 2Q or 3Q-Pc complex formed. Line 9 (80 L)-Line 11 (100 L) (bold black lines): A stable DNA–Pc complex
formed when 80 L, 0.62 mM CT-DNA was added to 2Q (a) or 3Q (b) and 70 L to 4Q (c).
lL 0.62 mM CT-DNA) were added to
l
l
l
l
l
l
l
l
groove binding but not intercalative binding [43]. These results
were in accordance with Ka values: 7.048 0.8 ꢃ 103 (for 2Q),
5.370 0.7 ꢃ 103 (for 3Q) and 2.089 0.8 ꢃ 103 (for 4Q).
cence, however, a greatly enhanced fluorescence upon DNA-
binding is observed at 540 nm [44]. When compared with the
other minor groove binders like DAPI (4,6-diamino-isophenylin-
dole) and Hoescht, SYBR is not sensitive to double or single strand
DNA and the structure is more stable in acidic or basic media [44].
Therefore, a competition of binding assay between SYBR and novel
quaternized pcs 2Q, 3Q and 4Q would demonstrate the mode of
interaction with DNA. This assay was easy to detect, as fluores-
cence of free SYBR–DNA complex was notably diminished by the
strong fluorescence quenching effects of quaternized compounds.
The quenching effect was determined by using Ksv constants (Ta-
ble 1). The Ksv value of 2Q was higher than 3Q and 4Q indicating
that the smaller the cationic group [45] the more binding affinity
to DNA and the more quenching effect on fluorescence of SYBR–
DNA complex is. The quenching process depends on the formation
of a stable pc–DNA complex less fluorescent than free pc. The more
the stable pc–DNA complex formed, the less the fluorescence was
observed. This means that DNA preferred pc instead of SYBR. Thus
the decrease in fluorescence emission evidenced the existance of
an effective interaction between pcs and DNA. These results were
in agreement with Ka values supporting an electrostatic external
binding to DNA phosphates (Table 1, Fig. 5).
3.3. Determination of binding 2Q, 3Q and 4Q to DNA using
fluorescence measurements
The data obtained from the titration of the compounds with
DNA also allowed calculating the drug/DNA association constants
(Ka), according to a previously proposed model [32] (Eq. (3)). The
association constants were given in Table 1 and Fig. 4 supporting
a non-intercalative but minor groove binding with DNA. Examina-
tion of the obtained Ka values allowed interpreting that the addi-
tion of small hydrophilic cationic groups in 2Q and 3Q increased
the affinity of the molecules towards DNA. Van Der Waals interac-
tions and hydrogen bonding are the main forces leading the smal-
ler molecules to the minor groove. Opposite to that, bulky
substituents such as phenyl rings in 4Q hindered the binding pro-
cess and decreased the affinity to DNA. Ka values were calculated
as 048 0.8 ꢃ 103, 5.370 0.7 ꢃ 103 and 2.089 0.8 ꢃ 103 for 2Q,
3Q and 4Q, respectively. The binding ratio of 2Q, 3Q and 4Q to
DNA is 0.61 0.8, 0.52 0.7 and 0.56 0.8, respectively.
These results were consistent with UV–Vis titrations indicating
a non-intercalative but minor groove binding with DNA.
3.5. Determination of the change in thermal denaturation profile of
DNA
3.4. Determination of quenching effect of 2Q, 3Q and 4Q on the
fluorescence intensity of DNA–SYBR complex by using Ksv constants
The DNA thermal melting is a measure of the stability of the
DNA double helix with temperature; an increase in the thermal
melting temperature (Tm) indicates an interaction between DNA
and the metal complex. In the present case, Tm values were deter-
SYBR Gold is a known DNA stain used in biological applications
[44]. In solution, the unbound SYBR exhibits very little fluores-

C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
359
Fig. 4. Fluorescence emission spectral changes of 2Q (a) 3Q (b) and 4Q (c) on addition of varying concentrations of DNA in water. Insets:The plot for determination of binding
constants of 2Q (a), 3Q (b) and 4Q (c) to DNA. All samples were excited at 610 nm.
Fig. 5. (a) The fluorescence emission spectral changes of SYBR–DNA complex (1ꢃ, 200
lL SYBR and 5 lM, 1.8 mL DNA) upon the additions of varying concentrations of 200 lL
2Q (a), 3Q (b) or 4Q (c). Insets: The plot drawn to determinate Ksv quenching constant of 2Q (a), 3Q (b) and 4Q (c) on the fluorescence of SYBR–DNA complex. All samples were
excited at 497 nm.

360
C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
Table 2
Explanation for R values in gel electrophoresis (agarose 1%) in Fig. 7, indicating the
interaction of 2Q, 3Q and 4Q with DNA.
R
[2Q]/[DNA]
[3Q]/[DNA]
[4Q]/[DNA]
0
aM
1
2
3
4
M
6
7
8
9
M
0.25 (1.25
0.5 (2.5
1 (5 L/5
1.5 (7.5
l
L/5
lL)
11
12
13
14
15
l
L/5
L)
L/5
L/5
l
L)
l
l
l
l
lL)
2.0 (10
l
L)
5
10
a
M is DNA marker to note the direction of migration.
Fig. 6. The thermal denaturation profiles of DNA in the absence and presence of 2Q,
3Q and 4Q.
Fig. 7. The gel electrophoresis pattern of DNA in the presence of 2Q, 3Q and 4Q. R
mined by monitoring the absorbance of DNA at 260 nm as a func-
tion of temperature. Tm of DNA in the absence of any added drug
was found to be 80 °C 0.2, under our experimental conditions.
Under the same set of conditions, the presence of complexes 2Q,
values were given in Table 2. M is DNA marker to note the direction of migration.
the highest R value was also observed. When the more neutraliza-
tion occurred, the less migration on the gel was seen. However,
more positive charge caused opposite migration which was seen
for compound 4Q. At low R value there was almost complete neu-
tralization and as seen in Fig. 7, quaternized 4Q was stuck in the
well together with DNA at the top of the gel. However, at a higher
R value caused a migration at opposite direction. This was due to
high positive charge of 4Q. According to Fig. 7, gel electrophoresis
pattern indicated that the cationic unit of pcs is neutralizing the
negative charges of DNA, thereby resulting the formation of a sta-
ble complex in case of 2Q and 3Q at high R values (charges on 2Q,
3Q and 4Q are 2+, 2+ and 6+, respectively) while 4Q does at low R
values because of its charge.
3Q and 4Q decreased
DTm by 2.5, 2.5 and 5 °C respectively. The
melting temperature of DNA (Tm) in the presence of a binding mol-
ecule can also be used to distinguish between intercalative and
external binding modes. Usually, classical intercalation gives rise
to higher
DTm values than either groove binding or outside stack-
ing [31]. The thermal denaturation results for the binding of 2Q–4Q
to CT-DNA are shown qualitatively in Fig. 6. As known, the absorp-
tion of double strand DNA is lower than the single strand DNA and
high pH values decrease Tm [46]. According to our experimental re-
sults, quaternized amines especially in compound 4Q increased pH
of the working solutions and denatured double strand DNA result-
ing the formation of single strand DNA due to scissoring at a lower
temperature (decreased Tm 5 °C) than 2Q and 3Q did (decreased Tm
2.5 °C). These results were consistent with the determined Ka val-
ues further stressing an external binding took place between
DNA and pcs.
3.7. Determination of photocleavage of plasmid DNA using gel
electrophoresis
Since the novel pcs presented here demonstrated DNA binding
property, the efficient use of these materials in PDT would be the
photocleavage of DNA. Thus, to observe this phenomenon, super-
coiled DNA was used and it was irradiated with a diode laser in
the presence of 2Q, 3Q and 4Q. The characteristic photodegrada-
tion of ADMA at 380 nm was observed when the solutions that
contain ADMA together with quaternized pcs were irradiated by
a diode laser (Fig. 8).
No DNA scission was observed when the photosensitizer was
kept in the dark even though 2Q, 3Q and 4Q were present. More-
over, to prove the the involvement of singlet oxygen in photoclea-
vage, we used sodium azide as singlet oxygen trap. In the absence
of sodium azide, nicked form was observed, opposing to the pres-
ence of singlet oxygen trap (Fig. 8: Lanes 7). When plasmid DNA
was subjected to electrophoresis, fast migration was observed for
the supercoiled (form I). If scission occured on one strand (nicking),
the supercoils would relax to generate a slower-moving open circu-
lar form (form II). A concentration-dependent DNA scission was
experienced for all quaternized pcs and the binding of pcs were
tested without irradiation at different concentrations (Fig. 7). Thus,
the effect of irradiation was evaluated at a constant concentration
of reactants with changing irradiation time. As shown in Fig. 8,
longer time of irradiation exhibited greater photodamage and
3.6. Determination of binding 2Q, 3Q and 4Q to DNA using gel
electrophoresis
The binding of quaternized pcs 2Q–4Q was examined with gel
electrophoresis. 1% agarose gel was prepared and TBE buffer was
used for staining solution. The migration of a series of dye/DNA
complexes of different ratios (Table 2) are shown in Fig. 7. It was
important to see whether DNA would prefer pcs or SYBR to bind.
Thus, the gels were stained by SYBR upon electrophoretic run. It
was observed that at low ratios of pcs to DNA, an excess of uncom-
plexed DNA was present as shown by the migration of the DNA
bands. The migration of DNA in the gel was regarded as the ratio
of dye to DNA increased, indicating that pcs were capable of bind-
ing to DNA, neutralizing its charges. Fig. 7 indicated that 2Q had
affinity to bind DNA and complete neutralization occurred be-
tween phosphates and quaternized amines of 2Q at an R value of
1.5. In case of 3Q, there was no complete neutralization between
positive and negative charges even at high R values such as 1.5
and 2. This was the evidence for hindrance of the interaction be-
tween DNA and bigger hydrophilic groups. Fig. 7 showed that there
was still uncomplexed DNA (in presence of 3Q) and migration at

C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
361
Ia)
IIa)
IIb)
Ib)
IIIa)
IIIb)
Fig. 8. The decreases in absorbance of ADMA at 380 nm in the presence of 2Q (Ia), 3Q (IIa) and 4Q (IIIa) due to singlet oxygen generation. Agarose (1%) gel electrophoresis
pattern for the photocleavage of pBR322 by 2Q (Ib), 3Q (IIb) and 4Q (IIIb). Reaction mixtures contained 10 L (0.2 g) pBR322. Lanes 1: pBR322 only. Lanes 2: 2Q (Ib), 3Q (IIb)
l
l
and 4Q (IIIb) + pBR322 + 1 min irradiation. Lanes 3: 2Q (Ib), 3Q (IIb) and 4Q (IIIb) + pBR322 + 3 min. irradiation. Lanes 4: 2Q (Ib), 3Q (IIb) and 4Q (IIIb) + pBR322 + 5 min
irradiation. Lanes 5: pBR322 + 2Q (Ib), 3Q (IIb) and 4Q (IIIb). Lanes 6: pBR322 + 5 min irradiation (k > 650). Lanes 7: 2Q (Ib), 3Q (IIb) and 4Q (IIIb) + pBR322 + 0.2 M sodium
azide + 5 min irradiation.
formed nicked form DNA. (Lanes 2–4 in Fig. 8: Ib, IIb and IIIb for 2Q,
3Q and 4Q respectively). The binding of pcs to supercoiled DNA was
proved with control groups without irradiation (Lanes 5 in Fig. 8: Ib,
IIb and IIIb). There was no effect of irradiation on supercoiled DNA
(Lanes 6 in Fig. 8: Ib, IIb, and IIIb). Therefore, these water soluble pcs
have the ability for DNA scission.
water soluble nature of drugs enhances the cellular uptake for
PDT. Thus, taking into consideration PDT activity, pcs which are
corporated with silicon were chosen to be examined.
The binding of all three quaternized compounds 2Q–4Q to DNA
was determined by using Ka binding constants, agarose gel electro-
phoresis, Stern Volmer quenching constants and thermal profiles of
DNA. According to our results, new quaternized pcs have the affin-
ity to bind to external phosphates of DNA backbone. Besides, sin-
glet oxygen generation of 2Q, 3Q and 4Q (Fig 8: Ia, IIa and IIIa)
was proved in aqueous media by the photodegradation of ADMA.
The combination of two different experiments; the binding affinity
of 2Q–4Q to DNA and singlet oxygen generation provided to dem-
onstrate the photocleavage of pBR322 via irradiation in the pres-
4. Conclusion
In the present work, both neutral and water soluble silicon pcs
were successfully accomplished. As known, cationic moieties can
bind to DNA either intercalatively or electrostatically [31,41] and

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C. Uslan, B. Sßebnem Sesalan / Inorganica Chimica Acta 394 (2013) 353–362
[18] R.L. Morris, M.E. Varnes, M.E. Kenney, Y.S. Li, N.L. Oleinick, Photochem.
Photobiol. 75 (2002) 652.
[19] L.Y. Xue, N.L. Oleinick, Oncogene 24 (2005) 6987.
ence of 2Q, 3Q or 4Q (Fig 8: Ib, IIb and IIIb). Thus, novel water sol-
uble silicon pcs might be the candidates for PDT or other biological
applications. The ongoing research on the response of these dyes in
organelles of yeasts is worthwhile.
[20] D.V. Sakharov, W.E. Hennink, C.F. Nostrum, J. Med. Chem. 50 (2007) 1485.
[21] E. Ben-Hur, J. Oetjen, B. Horowitz, Photochem. Photobiol. 65 (1997) 456.
[22] J. Mao, Y. Zhang, J. Zhu, C. Zhang, Z. Guo, Chem. Commun. (2009) 908.
[23] A. Voge, E. Lork, B.Sß. Sesalan, D. Gabel, J. Organomet. Chem. 694 (2009) 1698.
[24] B.Sß. Sesalan, A. Koca, A. Gül, Polyhedron 22 (2003) 3083.
[25] B.Sß. Sesalan, A. Koca, A. Gül, Chemie 131 (2000) 1191.
[26] B.Sß. Sesalan, A. Gül, Phosphorus Sulfur 178 (2003) 2081.
[27] B.Sß. Sesalan, A. Koca, A. Gül, Dyes Pigm. 79 (2008) 259.
[28] M.K. Gümüßstasß, B.Sß. Sesalan, P. Atukeren, B. Yılmaz, A. Gül, J. Coord. Chem. 63
(2010) 4319.
Acknowledgment
This work was supported by TUBITAK (110T527) and Research
Fund of Istanbul Technical University.
[29] B. Turanlı-Yıldız, T. Sezgin, Z.P. Çakar, C. Uslan, B.Sß. Sesalan, A. Gül, Synth. Met.
References
161 (2011) 1720.
[30] C. Uslan, B.Sß. Sesalan, Dyes Pigm. 94 (2012) 127.
[1] S. Riahi, S. Eynollahi, M.R. Ganjali, Chem. Biol. Drug Des. 76 (2010) 425.
[2] G. Bischoff, S. Hoffmann, Curr. Med. Chem. 9 (2002) 321.
[3] M. Wainwright, Biotech. Histochem. 85 (2010) 341.
[4] C.C. Leznoff, A.B.P. Lever, Phthalocyanines: Properties and Applications, vol. 1,
VCH, New York, 1989.
[5] N.B. McKeown, Cambridge University Press, 1998.
[6] K. Kadish, K.M. Smith, R. Guilard, The Porphyrin Handbook, vol. 15–20,
Academic Press, Boston, 2003.
[7] R. Haimovici, T.A. Ciulla, J.W. Miller, T. Hasan, T.J. Flotte, A.G. Kenney, Retina 22
(2002) 65.
[8] M. Eldar, Y. Yerushalmi, E. Kessler, M. Scheinowitz, U. Goldbourt, E. Ben-Hur, V.
Rosenthal, A. Battler, Atherosclerosis 84 (1990) 135.
[9] C. Monica, M. Michela, S. Marina, G. Jori, M. Moreno, I. Chambarier, M.J. Cook,
D.A. Russell, Eur. J. Cancer 46 (2010) 1910.
[10] P.C. Lo, C.M.H. Chan, J.Y. Liu, W.P. Fong, D.K.P. Ng, J. Med. Chem. 50 (2007)
2100.
[11] M. Çamur, V. Ahsen, M. Durmußs, J. Photochem. Photobiol. A 219 (2011) 217.
[12] F. Dumoulin, M. Durmus, V. Ahsen, T. Nyokong, Chem. Rev. 254 (2010) 2792.
[13] M. Durmusß, V. Ahsen, J. Inorg. Biochem. 104 (2010) 297.
[14] E. Ben-Hur, I. Rosenthal, Int. J. Radiat. Biol. 47 (1985) 145.
[15] R.L. Morris, A. Kashif, M. Lam, J. Berlin, A.L. Nieminen, M.E. Kenney, A.C.S.
Samia, C. Burda, N.L. Oleinick, Cancer Res. 63 (2003) 5194.
[16] N.L. Oleinick, A.R. Antunez, M.E. Clay, B.D. Rihter, M.E. Kenney, Photochem.
Photobiol. 57 (1993) 242.
[31] W. Duan, W. Zhenxin, M.J. Cook, J. Porphyrins Phthalocyanines 13 (2009) 1255.
[32] X.Z. Feng, Z. Lin, L.J. Yang, C. Wang, C. Bai, Talanta 47 (1998) 1223.
[33] E. Safaei, B. Ranjbar, L. Hasani, J. Porphyrins Phthalocyanines 11 (2007) 805.
[34] J.H. Brannon, D.J. Madge, Am. Chem. Soc. 102 (1980) 62.
[35] I. Seotsanyana-Mokhosi, N. Kuznetsova, T. Nyokong, J. Photochem. Photobiol. A
140 (2001) 215.
[36] W. Spiller, H. Kliesch, D. Wöhrle, S. Hackbarth, B. Roder, G. Schnurpfeil, J.
Porphyrins Phthalocyanines 2 (1998) 145.
[37] X.J. Jiang, P.C. Lo, Y.M. Tsang, S.L. Yeung, W.P. Fong, D.K.P. Ng, Chem. Eur. J. 16
(2010) 4777.
[38] H. Li, T.J. Jensen, F.R. Fronczek, M.G.H. Vicente, J. Med. Chem. 51 (2008) 502.
[39] X.J. Jiang, J.D. Huang, Y.J. Zhu, F.X. Tang, D.K.P. Ng, J.C. Sun, Bioorg. Med. Chem.
Lett. 16 (2006) 2450.
[40] M.E. Anderson, A.G.M. Barrett, B.M. Hoffman, J. Inorg. Biochem. 80 (2000) 257.
[41] A.M. Zhanga, J. Huanga, X. Wenga, J.X. Lia, L.G. Rena, Z. Songa, X. Xionga, X.
Zhou, X. Caod, Y. Zhoue, Chem. Biodivers. 4 (2007) 215.
[42] M.J. Lee, B. Jin, H.M. Lee, M.J. Jung, S.K. Kim, J.M. Kim, Bull. Korean Chem. Soc.
29 (2008) 1533.
[43] M. Monajjemi, H. Aghaie, F. Naderi, Biochemistry (Moscow) 72 (2007) 652.
[44] G. Cosa, K.S. Focsaneanu, J.R.N. McLean, J.P. McNamee, J.C. Scaiano, Photochem.
Photobiol. 73 (2001) 585.
[45] V. Jadhav, S. Maiti, Biomacromolecules 9 (2008) 1852.
[46] K.R. Fox, Drug-DNA Interaction Protocols, vol. 90, Humana Press, New Jersey,
1997.
[17] S.I.A. Zaidi, R. Agarwal, G. Eichler, B.D. Rihter, M.E. Kenney, H. Mukhtar,
Photochem. Photobiol. 58 (1993) 204.