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irradiation, the production of a greater amount of ROS by phthalo-
cyanine 6 led to a more effective cell death. Besides, phthalocyanine
6 was more photoactive in vitro than Pc13 [10], since the IC50 values
obtained under similar experimental conditions were two-fold
through a silica gel column packed and pre-washed with the same
solvent. Evaporation of the solvent gave a viscous oil; yield: 0.070 g
(79%). IR (KBr, cmꢁ1): 3812, 3444, 3414, 3267, 3165, 3095, 3058,
2964, 2936, 2931, 2874, 2734, 2675, 2568, 2344, 2231 (CN), 1942,
1743 (CO), 1692, 1638, 1583, 1545, 1465, 1422, 1378, 1261, 1210, 1192,
1163, 1126, 1094, 1072, 1028, 871, 834, 802, 753, 648, 599, 525, 496.
higher for 6 than for Pc13 (IC50 ¼ 2.7 ꢃ 0.6
mM) [10].
Summarizing, it is possible to consider a structureeactivity
relationship of alkylthio peripheral substituted zinc(II) phthalocy-
anines for photobiological purposes. Therefore, further photobio-
logical studies, as well as search for improved phthalocyanine
structures, are already in progress.
1H NMR (300 MHz, CDCl3):
d (ppm) 0.95 (t, 3H, CH3), 1.30 (m, 4H,
CH2), 1.67 (m, 2H, CH2), 2.28 (t, 2H, NCOCH2), 3.18 (s, 2H, SCH2),
3.25(t, 2H, NCH2), 3.50 (t, 2H, CH2N), 7.68e7.87 (m, 3H, Ar). ESI-TOF
MS: m/z (%) [Mþ] calcd. for: C18H23N3SO 329.1562; found: [M þ H]þ
330.2000.
4. Experimental
4.1.4. 2,9(10),16(17),23(24)-Tetrakis[(N-butyryl-N-butylamino)
ethylsulfanyl]phthalocyaninatozinc(II) (4)
4.1. Materials and methods
A mixture of 3 (0.137 g, 0.42 mmol), anhyd Zn(OAc)2 (0.139 g,
0.75 mmol), and DBU (0.14 mL, 0.94 mmol) was stirred and heated
at 160 ꢀC for 5 min under Ar. After cooling, it was treated with
CH2Cl2 (5 mL) and centrifuged to eliminate the excess of Zn(OAc)2.
The organic solution was evaporated in vacuo leaving a blue-green
residue, that was then dissolved in CH2Cl2 and filtered through
a column with silica-gel packed and pre-washed with the same
solvent. The title compound was eluted with CH2Cl2-MeOH
(9.5:0.5). After evaporation in vacuo, the dye was obtained (0.082 g,
57% yield). IR (KBr, cmꢁ1): 3058, 2661, 2932, 2873, 2650, 2565,
2416, 2230, 1732 (CO), 1635, 1599, 1583, 1545, 1459, 1426, 1476,
1293, 1261, 1209,1125, 1094,1072,1036, 978, 910, 871, 830, 760, 747,
4.1.1. Synthesis of photosensitizers
Melting points were determined on an Electrothermal 9100
capillary melting point apparatus. 1H NMR of precursors were
recorded on a Bruker MSL 300 spectrometer while 1H NMR of
phthalocyanines on a Bruker AM 500. Intermediates ESI-TOF mass
spectroscopy was determined with a ZQ Micromass spectrometer,
while phthalocyanines ESI-TOF mass spectra were measured with
an LTQ ion trap equipment. Electronic absorption spectra were
determined with a Shimadzu UV-3101 PC spectrophotometer.
Fluorescence spectra were monitored with a QuantaMaster Model
QM-1 PTI spectrofluorometer. Infrared spectra were performed
with a Perkin Elmer Spectrum One FT-IR spectrometer.
649, 598, 524. 1H NMR (500 MHz, CDCl3):
d (ppm) 0.79 (m, 24H,
Chromatography columns were prepared with TLC Kiesegel
(Merck), and Aluminum Oxide 90 standardized (Merck). N,
N-dimethylformamide was dried over 3Ǻ molecular sieves during
72 h, then filtered and freshly distilled before utilization [22]
Diphenylisobenzofuran (DPBF) as well as all reagents were
provided by SigmaeAldrich. 2,3,9,10,16,17,23,24-octakis[(N,N-
dimethylaminoethylsulfanyl)]phthalocyaninatozinc(II) [4] was
synthesized in our laboratory.
CH3), 1.11 (m, 16H, CH2CH3), 1.45 (m, 8H, CH2CH2CH3), 2.12 (t, 8H,
COCH2CH2CH3), 3.07 (m, 8H, CH2CH2CH2CH3), 3.32 (br, 8H, CH2N),
5.13 (br s, 8H, SCH2), 7.53e7.70 (m, 12H, Ar). ESI-TOF MS: m/z (%)
[Mþ] cald for: C72H92N12O4S4Zn 1383.2300; found: [Mþ] 1383.4700.
4.1.5. 2,9(10),16(17),23(24)-Tetrakis[(N,N-dibutylamino)
ethylsulfanyl]phthalocyaninatozinc(II) (5)
BF3.Et2O (25 mL) was slowly dropped into a suspension of
NaBH4 (7.5 g) in diglyme (25 mL) and the resulting B2H6 was
bubbled through a suspension of 4 (0.100 g, 0.072 mmol) in anhyd
THF (15 mL). The mixture was stirred for 48 h, poured into hexane
and the blue-green precipitate was centrifuged, dried, and then
applied to an Al2O3 column packed and pre-washed with toluene.
After washing with toluene and CH2Cl2, the title compound was
eluted with CH2Cl2-MeOH (8:2). After solvent evaporation, a green
product was obtained. Yield: 0.076 g (79%).
4.1.2. 4-[2-(N-butylamino)ethylsulfanyl]phthalonitrile (2)
A mixture of 4-nitrophthalonitrile (0.1 g, 0.58 mmol), 2-(buty-
lamino)-ethanethiol (0.4 mL, 0.59 mmol), and K2CO3 (0.24 g,
1.74 mmol) in anhyd DMF (1 mL) was stirred for 24 h at r.t. under Ar
and then poured into H2O (30 mL) and extracted with CH2Cl2
(4 ꢄ 20 mL). The combined extracts were washed with H2O
(4 ꢄ 20 mL), dried (Na2SO4), and evaporated in vacuo. The solid
residue was dissolved in a small volume of CH2Cl2-MeOH (9:1) and
the solutionwas filtered through a silica gel column that was packed
and pre-washed with the same solvent. Evaporation of the solvent
gave highly viscous oil, yield: 0.091 (61%). IR (KBr, cmꢁ1): 3812, 3437,
3431, 3401, 3384, 3317, 3205, 3098, 3059, 2957, 2929, 2871, 2850,
2572, 2429, 2381, 2231 (CN),1942,1667,1600,1583,1545,1507,1467,
1386,1293,1263, 1217, 1191, 1126, 1070, 872, 834, 738, 721, 650, 605,
IR (KBr, cmꢁ1): 3088, 3064, 3030, 2957, 2932, 2871, 2354, 2347,
2341, 2280, 2086, 1955, 1815, 1673, 1601, 1554, 1495, 1454, 1383,
1338, 1206, 1173, 1080, 1047, 1024, 910, 833, 770, 744, 735, 699, 596.
1H NMR (500 MHz, CDCl3):
d (ppm) 0.72 (m, 24H, CH3), 1.09 (br,
16H, CH2CH3), 1.52 (br, 16H, CH2CH2CH3), 3.32 (br, 16H,
CH2CH2CH2CH3), 4.54 (br s, 8H, CH2N), 5.13 (br s, 8H, SCH2),
7.19e7.21 (m, 12H, Ar). ESI-TOF MS: m/z (%) [Mþ] cald for:
C72H100N12S4Zn: 1327.2992; found: [Mþ] 1327.3100.
598, 524, 497. 1H NMR (300 MHz, CDCl3):
d (ppm) 0.92 (t, 3H, CH3),
1.39 (m, 4H, CH2), 2.64 (t, 2H, NHCH2), 2.88 (s, 1H, NH), 2.96 (t, 2H,
CH2NH), 3.18 (t, 2H, SCH2), 7.52e7.66 (m, 3H, Ar). ESI-TOF MS: m/z
(%) [Mþ] calcd. for: C14H17N3S 259.1143; found: [M þ H]þ 260.1000.
4.1.6. 2,9(10),16(17),23(24)-Tetrakis[(N,N-dibutyl-N-
methylammonium)ethylsulfanyl]phthalocyaninatozinc(II)
tetraiodide (6)
4.1.3. 4-[2-(N-butyryl-N-butylamino)ethylsulfanyl]phthalonitrile (3)
A solution of butyryl chloride (0.17 mL, 1.5 mmol) in anhyd
CH2Cl2 (5 mL) was added dropwise to a stirred cold solution of
amine 2 (0.070 g, 0.27 mmol) in anhyd pyridine (1.7 mL). The
mixture was then stirred for 48 h at r. t. CH2Cl2 (30 mL) was added
and the mixture was washed sequentially with 1 N HCl (4 ꢄ 20 mL)
and H2O (1 ꢄ 20 mL). The organic phase was washed again with 5%
NaHCO3 soln (2 ꢄ 20 mL) and H2O (1 ꢄ 20 mL), then dried (Na2SO4)
and evaporated to dryness in vacuo. The oil residue was dissolved in
a small volume of CH2Cl2-MeOH (9:1) and the solution was filtered
MeI (12 mL, 0.2 mol) was added to a solution of phthalocyanine
5 (0.066 g, 0.05 mmol) in CH2Cl2 (15 mL) and the solution was
stirred for 48 h at 60 ꢀC. After cooling at r. t., the blue-green powder
was centrifuged, suspended in CH2Cl2 (5 mL), and centrifuged
again. Yield 0.063 g (67%).
IR (KBr, cmꢁ1): 3900, 3817, 3745, 3733, 2930, 2856, 2506, 2354,
2347, 2275, 2051,1967,1868,1831,1665,1494,1439,1411,1390,1256,
1097, 1065, 662. 1H NMR (500 MHz, CDCl3):
d (ppm) 0.99 (t, 24H,
CH3), 1.23 (br s, 16H, CH2CH3), 1.67 (br, 16H, CH2CH2CH3), 3.66 (br,
16H, CH2CH2CH2CH3), 3.68 (br, 12H, CH3), 3.69 (br, 8H,CH2N),