Novel phthalocyanines bearing four 4-phenyloxyacetic acid functionalities

Article abstract of DOI:10.1016/j.poly.2007.01.010

Metal-free (2) and Co(II), Zn(II), Ni(II), Cu(II) metallophthalocyanines (2a-d) with four 4-phenyloxyacetic acid groups on the periphery were prepared by cyclotetramerization of new p-(3,4-dicyanophenoxy)phenylacetic acid (1) and the corresponding divalen

Full text of DOI:10.1016/j.poly.2007.01.010

Polyhedron 26 (2007) 2638–2646
www.elsevier.com/locate/poly
Novel phthalocyanines bearing four 4-phenyloxyacetic
acid functionalities
*
¨
Meryem C¸ amur, Ali Rıza Ozkaya, Mustafa Bulut
Marmara University, Department of Chemistry, 34722 Istanbul, Turkey
Received 27 October 2006; accepted 10 January 2007
Available online 21 January 2007
Abstract
Metal-free (2) and Co(II), Zn(II), Ni(II), Cu(II) metallophthalocyanines (2a–d) with four 4-phenyloxyacetic acid groups on the
periphery were prepared by cyclotetramerization of new p-(3,4-dicyanophenoxy)phenylacetic acid (1) and the corresponding divalent
metal salts. Further reactions of these products with thionylchloride and then benzylamine in tetrahydrofuran, and octanol in pyridine
gave amide (3, 3a–d) and ester (4, 4a–d) derivatives, respectively. The new compounds have been characterized by elemental analyses, IR,
1
UV–Vis, mass and H NMR spectroscopy. The redox properties of compounds 2 and 2a–d were identified by cyclic voltammetry.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Phthalocyanines; 4-Hydroxyphenylacetic acid; Esterification; Metallophthalocyanines; Electrochemistry; Cyclic voltammetry
1. Introduction
uents on the peripheral position of the macrocycle increases
drastically their solubility in organic solvents. In addition to
the solubility, the spectral properties of phthalocyanines are
also strongly influenced by the peripheral substituents on
the macrocycles [12,13].
The phthalocyanine unit with an 18p electron aromatic
system and its metal center in some cases is capable of oxi-
dation or reduction. These redox processes depend on var-
ious factors such as the type of the central metal, solvent,
axial ligands and substituents. The redox properties of pht-
halocyanines are critically related to most of their indus-
trial applications. Cyclic voltammetry is the most widely
used method to determine electrochemical properties in
solution.
The present paper reports for the first time the synthesis
and characterization of p-(3,4-dicyanophenoxy)phenylace-
tic acid from a single step reaction and its conversion into
metal-free and metallophthalocyanines [M = Co(II),
Zn(II), Ni(II) and Cu(II)] containing tetrakis(4-phenyloxy-
acetic acid) moieties at the periphery. Cyclic voltammetry
of these compounds is also presented. The reactivity of
the phenyloxyacetic acid substituents has been demon-
strated by the preparation of better soluble esters than
these pcs.
Phthalocyanines (Pcs) form an important class of macro-
cyclic compounds which do not occur in nature [1]. Follow-
ing the first synthesis in 1907, they have been established as
blue and green dyestuffs, and their recent use as the photo-
conducting agent in photocopying machines has provoked
research in various fields, including electrochromism, pho-
tovoltaic cell elements for electricity generation, electropho-
tography, application to optical computer read/write discs,
low-dimensional metals, non-linear optics, electrocatalysis,
liquid crystals, Langmuir–Blodgett films [2–8], chemical
sensors [9] and photodynamic reagents for cancer therapy
and other medical applications [10,11]. The two variables
are the central metal ion and peripheral substituents: the
possibility of inserting a great number of different metal
ions into the phthalocyanine core is combined with the
unlimited number and type of substituents, the variety of
novel products is infinite. The introduction of bulky substit-
*
Corresponding author. Tel.: +90 216 3479641/1370; fax: +90 216
3478783.
E-mail addresses: mbulut@marmara.edu.tr, mustafabulut50@gmail.-
com (M. Bulut).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.01.010

M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
2639
2. Experimental
water, hot acetonitrile, hot methanol, chloroform and
diethyl ether, and dried. It is soluble in DMF, DMSO
and pyridine. Yield: 0.255 g (51%). M.p. >300 °C. Anal.
Calc. for C64H42N8O12: C, 68.94; H, 3.77; N, 10.05. Found:
C, 68.89; H, 3.68; N, 10.11%. FT-IR (KBr), mmax/(cmꢀ1):
3410 (carboxylic acid OH), 3290 (NH), 3037 (Ar–CH),
2955–2866 (aliphatic CH), 1715 (C@O), 1603–1474 (Ar
C@C), 1232 (Ar–O–Ar), 1165, 1090, 1013, 932, 831, 745,
644 and 608. 1H NMR (d-DMSO 500 MHz, d ppm):
12.40 (br s, 4H, COOH), 7.24–6.02 (m, 28H, Ar–H), 3.97
(s, 8H, CH2), ꢀ7.22 (br s, 2H, NH). MS (LC-MS, Scan
ES+) m/z: 1114 [M+]. UV–Vis kmax (nm) (loge) in DMF:
287 (4.82), 340 (4.87), 638 (4.74), 667 (4.79), 699 (4.69).
2.1. Synthesis
IR spectra were recorded on a Shimadzu FTIR-8300
Fourier Transform Infrared spectrophotometer using
KBr pellets, UV–VIS spectra on a Shimadzu UV-1601
UV–Vis spectrophotometer, and H and 13C NMR spec-
1
tra on a Varian UNITY INOVA 500 MHz spectrometer.
Elemental analysis were performed by the Instrumental
Analysis Laboratory of the TUBITAK Marmara
Research Centre. Mass spectra were recorded on a Varian
711 spectrometer. 4-Nitrophthalonitrile was synthesized
according to the reported procedure [14] and 4-hydroxy-
phenylacetic acid was purchased from Fluka Chemical
Company, and was used as purchased. All reagents and
solvents were of reagent-grade quality obtained from
commercial suppliers. All solvents were dried and puri-
fied. The solvents were stored over molecular sieves
2.1.3. General procedure for the 2,9,16,23-tetrakis
(4-phenyloxyacetic acid)phthalocyaninatometal derivatives
(2a–d)
A mixture of compound 2 (0.05 g, 0.045 mmol) and
0.45 mmol metal salts [CoCl2 Æ 6H2O 0.11 g, Zn-
(AcO)2 Æ 2H2O 0.10 g, NiCl2 Æ 6H2O 0.11 g or CuCl2
0.06 g] in dry DMF (1.5 ml) was heated and stirred at
155 °C for 24 h under N2 in a sealed glass tube. After cool-
ing to room temperature, the reaction mixture was treated
with diluted HCl. After that, the precipitated green-blue
solid was filtered off. The product was washed with water,
hot methanol, hot acetonitrile and diethyl ether, and dried.
˚
(4 A). The homogeneity of the products were tested in
each step by TLC (SiO2).
2.1.1. p-(3,4-Dicyanophenoxy)phenylacetic acid (1)
4-Hydroxyphenylacetic acid (0.88 g, 5.78 mmol) and
4-nitrophthalonitrile (1.0 g, 5.78 mmol) were dissolved in
dry DMF (100 ml) under nitrogen and anhyd. K2CO3
(1.60 g, 11.56 mmol) was added. After stirring for 24 h at
50–60 °C, the reaction mixture was treated with diluted
HCl under ice cooling. The pure precipitate was filtered,
washed with water to neutralize, and dried. Yield: 0.812 g
(50.73%). M.p. 177–180 °C. FT-IR (KBr), mmax/(cmꢀ1):
3500 (carboxylic acid OH), 3067–3050 (Ar–CH), 2930–
2918 (aliphatic CH), 2231 (C„N), 1703 (C@O), 1588–
1488 (Ar C@C), 1246 (Ar–O–Ar), 1205, 1161, 1079, 942,
2.1.3.1. 2,9,16,23-Tetrakis(4-phenyloxyacetic acid)phtha-
locyaninatocobalt (II) (2a). This is soluble in THF,
DMF, DMSO and pyridine. Yield: 0.029 g (55%). M.p.
>300 °C. Anal. Calc. for C64H40N8O12Co: C, 65.58; H,
3.42; N, 9.56. Found: C, 65.86; H, 3.39; N, 9.73%. FT-IR
(KBr), mmax/(cmꢀ1): 3396 (carboxylic acid OH), 3045 (Ar–
CH), 2925–2866 (aliphatic CH), 1728 (C@O), 1603–1474
(Ar C@C), 1232 (Ar–O–Ar), 1161, 1094, 1057, 1016, 953,
880, 824, 745, 671 and 579. MS (LC-MS, Scan ES+) m/z:
1171 [M+]. UV–Vis kmax (nm) (loge) in DMF: 328 (4.90),
662 (5.03).
1
842, 801, 664 and 523. H NMR (d-DMSO 500 MHz, d
ppm): 12.36 (s, 1H, COOH), 8.09 (d, 1H, Ar–H), 7.77 (d,
1H, Ar–H), 7.39 (d, 1H, Ar–H), 7.35 (dd, 2H, Ar–H),
7.15 (dd, 2H, Ar–H), 3.63 (s, 2H, CH2). 13C NMR
(d-DMSO 500 MHz, d ppm): 173.20 (acid C@O), 161.83
(Ar–C), 153.17 (Ar–C), 137.02 (Ar–C), 133.38 (Ar–C),
132.28 (Ar–C), 123.38 (Ar–C), 122.58 (Ar–C), 120.81
(Ar–C), 117.40 (Ar–C), 116.61 (C„N), 116.09 (C„N),
108.80 (Ar–C). MS (LC–MS, Scan ES+) m/z: 278 [M+].
UV–Vis kmax (nm) (loge) in CHCl3: 306 (3.73).
2.1.3.2. 2,9,16,23-Tetrakis(4-phenyloxyacetic acid)phtha-
locyaninatozinc (II) (2b). This is soluble in THF, DMF,
DMSO and pyridine. Yield: 0.038 g (72%). M.p. >300 °C.
Anal. Calc. for C64H40N8O12Zn: C, 65.25; H, 3.40; N,
9.53. Found: C, 65.16; H, 3.47; N, 9.65%. FT-IR (KBr),
m
max/(cmꢀ1): 3402 (carboxylic acid OH), 3067–3030 (Ar–
2.1.2. 2,9,16,23-Tetrakis(4-phenyloxyacetic
acid)phthalocyanine (2)
CH), 2925–2866 (aliphatic CH), 1728 (C@O), 1603–1470
(Ar C@C), 1232 (Ar–O–Ar), 1161, 1090, 1045, 1016, 941,
889,864, 824, 745 and 664. 1H NMR (d-DMSO
500 MHz, d ppm): 12.40 (br s, 4H, COOH), 8.00–7.20 (b,
28H, Ar–H), 3.31 (s, 8H, CH2). MS (LC-MS, Scan ES+)
m/z: 1177 [M+]. UV–Vis kmax (nm) (loge) in DMF: 356
(4.77), 612 (4.44), 679 (5.13).
Compound 1 (0.5 g, 1.80 mmol) and lithium metal
(0.2 g, 28.6 mmol) were heated and stirred at 170 °C for
3 h under nitrogen in a mixture of 1,2-dichlorobenzene
(4 ml) and pentanol (4 ml). After cooling to room temper-
ature, acetonitrile was added in order to precipitate the
product. The green precipitate was filtered and then
washed with water and acetonitrile. It was dissolved in a
small amount of methanol and precipitated by diluted
HCl. In this mixture, the Li2pcs formed was converted into
H2pcs. The green precipitate was filtered and washed with
2.1.3.3. 2,9,16,23-Tetrakis(4-phenyloxyacetic acid)phtha-
locyaninatonickel (II) (2c). This is soluble in THF,
DMF, DMSO and pyridine. Yield: 0.045 g (85.6%). M.p.
>300 °C. Anal. Calc. for C64H40N8O12Ni: C, 65.58; H,

2640
M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
3.42; N, 9.56. Found: C, 65.06; H, 3.37; N, 9.45%. FT-IR
(KBr), mmax/ (cmꢀ1): 3425 (carboxylic acid OH), 3067–
3038 (Ar–CH), 2926–2918 (aliphatic CH), 1722 (C@O),
1599–1410 (Ar C@C), 1234 (Ar–O–Ar), 1161, 1121, 1086,
1057, 953, 883, 824, 748, 671 and 644. 1H NMR (d-DMSO
500 MHz, d ppm): 12.80 (br s, 4H, COOH), 7.74–7.23 (b,
28H, Ar–H), 3.24 (s, 8H, CH2). UV–Vis kmax (nm) (loge)
in DMF: 333 (4.48), 609 (4.58), 672 (4.40).
1603–1462 (Ar C@C), 1254 (Ar–O–Ar), 1198,1161, 1117,
1020, 984,916, 824, 748, 696, 604 and 503. MS (LC-MS,
Scan ES+) m/z: 1527 [M+]. UV–Vis kmax (nm) (loge) in
DMF: 330 (4.79), 667 (4.75).
2.1.4.3. 2,9,16,23-Tetrakis(N-benzyl-4-phenyloxyacetamide)
phthalocyaninatozinc (II) (3b). This is soluble in THF,
DMF, DMSO and pyridine. Yield: 0.016 g (60.2%). M.p.
>300 °C. Anal. Calc. for C92H68N12O8Zn: C, 72.02; H,
4.44; N, 10.96. Found: C, 72.16; H, 4.62; N, 10.72%. FT-
IR (KBr), mmax/(cmꢀ1): 3290 (NH), 3067–3022 (Ar–CH),
2918–2858 (aliphatic CH), 1728 (C@O), 1651 (amide NH),
1603–1462 (Ar C@C), 1250 (Ar–O–Ar), 1161, 1094, 1016,
2.1.3.4. 2,9,16,23-Tetrakis(4-phenyloxyacetic acid)phtha-
locyaninatocopper (II) (2d). This is soluble in THF,
DMF, DMSO and pyridine. Yield: 0.029 g (55%). M.p.
>300 °C. Anal. Calc. for C64H40N8O12Cu: C, 65.33; H,
3.40; N, 9.53. Found: C, 65.63; H, 3.36; N, 9.85%. FT-IR
(KBr), mmax/(cmꢀ1): 3410 (carboxylic acid OH), 3074–
3030 (Ar–CH), 2918-2850 (aliphatic CH), 1715 (C@O),
1603–1466 (Ar C@C), 1232 (Ar–O–Ar), 1165, 1094, 1049,
1016, 953, 872, 824, 741, 671 and 648. UV–Vis kmax (nm)
(loge) in DMF: 342 (4.63), 626 (4.56), 678 (4.71).
1
976,897, 831, 764, 696, 596 and 507. H NMR (d-DMSO
500 MHz, d ppm): 8.70 (s, 4H, –CONH), 7.78–7.01 (b,
48H, Ar–H), 4.42 (d, 8H, –NHCH2Ar),. UV–Vis
kmax (nm) (loge) in DMF: 360 (4.77), 614 (4.49), 683
(5.15).
2.1.4.4. 2,9,16,23-Tetrakis(N-benzyl-4-phenyloxyacetamide)
phthalocyaninatonickel (II) (3c). This is soluble in DMF,
DMSO and pyridine. Yield: 0.017 g (66%). M.p. >300 °C.
Anal. Calc. for C92H68N12O8Ni: C, 72.29; H, 4.45; N,
11.00. Found: C, 72.56; H, 4.28; N, 10.84%. FT-IR (KBr),
2.1.4. General procedure for the N-benzylamide derivatives
of phthalocyanine (3, 3a–d)
The phthalocyanine derivatives (2, 2a–d) (0.02 g) were
refluxed for 4 h in thionylchloride (2 ml). At the end of
the reaction, thionylchloride was removed under reduced
pressure. The resulting solid was dissolved in dry THF
(1 ml). Dry benzylamine (0.5 ml, 4.58 mmol) was dissolved
in dry THF (1 ml) and dropped into the acid chloride at
10 °C. The mixture was stirred at room temperature for
15–16 h. After the reaction, THF was removed under
reduced pressure. The reaction mixture was treated with
water to precipitate the product, and filtered. The products
were washed with water, methanol, acetonitrile and diethyl
ether, and dried.
m
max/(cmꢀ1): 3388 (NH), 3059–3030 (Ar–CH), 2934–2851
(aliphatic CH), 1736 (C@O), 1647 (amide NH), 1595–1458
(Ar C@C), 1254 (Ar–O–Ar), 1202, 1165, 1109, 1016, 989,
920, 839, 745, 692, 596 and 511. 1H NMR (d-DMSO
500 MHz, d ppm): 8.67 (s, 4H, –CONH), 7.68–7.11 (b,
48H, Ar–H), 4.45 (d, 8H, –NHCH2Ar). UV–Vis kmax
(nm) (loge) in DMSO: 287 (4.47), 621 (4.01), 672
(3.79).
2.1.4.5. 2,9,16,23-Tetrakis(N-benzyl-4-phenyloxyacetamide)
phthalocyaninatocopper (II) (3d). This is soluble in DMF,
DMSO and pyridine. Yield: 0.018 g (71%). M.p. >300 °C.
Anal. Calc. for C92H68N12O8Cu: C, 72.09; H, 4.44; N,
10.97. Found: C, 72.27; H, 4.18; N, 10.62%. FT-IR (KBr),
2.1.4.1. 2,9,16,23-Tetrakis(N-benzyl-4-phenyloxyacetamide)
phthalocyanine (3). This is soluble in DMF, DMSO and
pyridine. Yield: 0.014 g (53.4%). M.p. >300 °C. Anal. Calc.
for C92H70N12O8: C, 75.10; H, 4.76; N, 11.43. Found: C,
75.16; H, 4.47; N, 11.12%. FT-IR (KBr), mmax/(cmꢀ1):
3290 (NH), 3059–3030 (Ar–CH), 2918–2850 (aliphatic
CH), 1728 (C@O), 1655 (amide NH), 1603–1462 (Ar
C@C), 1250 (Ar–O–Ar), 1165, 1132, 1094, 1028, 949,
827, 745, 696, 599 and 507. 1H NMR (d-DMSO
500 MHz, d ppm): 8.65 (s, 4H, –CONH), 7.63–7.11 (b,
48H, Ar–H), 4.31 (d, 8H, –NHCH2Ar), ꢀ8.00 (br s, 2H,
NH). MS (LC-MS, Scan ES+) m/z: 1470 [M+]. UV–Vis
kmax (nm) (loge) in DMSO: 302 (4.28), 330 (4.28), 646
(4.17), 682 (4.36), 704 (4.30).
m
max/(cmꢀ1): 3396 (NH), 3067–3022 (Ar–CH), 2926–2858
(aliphatic CH), 1740 (C@O), 1647 (amide NH), 1595–1462
(Ar C@C), 1246 (Ar–O–Ar), 1161, 1109, 1016, 984, 905,
841, 745, 700, 599 and 515. (LC-MS, Scan ES+) m/z: 1531
[M+]. UV–Vis kmax (nm) (loge) in DMSO: 344 (4.48), 627
(4.42), 679 (4.44).
2.1.5. General procedure for the synthesis of octylacetate
derivatives of phthalocyanine (4, 4a–d)
A mixture of the phthalocyanine derivatives (2, 2a–d)
(0.02 g) and thionylchloride (2 ml) were refluxed for 4 h.
At the end of the reaction, thionylchloride was removed
under reduced pressure. The resulting solid was dissolved
in dry pyridine (0.5 ml, 3.17 mmol). Dry octanol (0.5 ml)
was dissolved in dry pyridine (0.5 ml) and dropped into
acid chloride at 0 °C. The mixture was stirred at 50–
60 °C for 30 min at room temperature for 15–16 h, and
poured into cold diluted HCl. The oily product was trea-
ted with diethyl ether to precipitate the ester. The crude
2.1.4.2. 2,9,16,23-Tetrakis(N-benzyl-4-phenyloxyacetamide)
phthalocyaninatocobalt (II) (3a). This is soluble in THF,
DMF, DMSO and pyridine. Yield: 0.022 g (84.3%). M.p.
>300 °C. Anal. Calc. for C92H68N12O8Co: C, 72.29; H,
4.45; N, 11.00. Found: C, 72.34; H, 4.62; N, 11.12%. FT-
IR (KBr), mmax/(cmꢀ1): 3290 (NH), 3074–3030 (Ar–CH),
2926–2858 (aliphatic CH), 1726 (C@O), 1651 (amide NH),

M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
2641
product washed with water and dried , purified on silica
gel column chromatography with chloroform as the
eluent.
CH3). UV–Vis kmax (nm) (loge) in DMSO: 287 (4.75),
339 (4.39), 617 (4.49), 664 (4.25).
2.1.5.5. 2,9,16,23-Tetrakis(octyl 4-phenyloxyacetate)phtha-
locyaninatocopper (II) (4d). This is soluble in THF,
CHCl3, CH2Cl2, DMF, DMSO and pyridine. Yield:
0.020 g (74%). M.p. >300 °C. Anal. Calc. for
C96H104N8O12Cu: C, 70.96; H, 6.41; N, 6.90. Found: C,
70.62; H, 6.52; N, 7.04%. FT-IR (KBr), mmax/(cmꢀ1):
3067 (Ar–CH), 2926–2858 (aliphatic CH), 1732 (C@O),
1591–1462 (Ar C@C), 1246 (Ar–O–Ar), 1165–1101 (ester
C–O), 1020, 980, 908, 841, 741, 619 and 519. UV–Vis kmax
(nm) (loge) in DMSO: 346 (4.20), 630 (4.17), 641 (4.12),
679 (4.21).
2.1.5.1. 2,9,16,23-Tetrakis(octyl 4-phenyloxyacetate)phtha-
locyanine (4). This is soluble in THF, CHCl3, CH2Cl2,
DMF, DMSO and pyridine. Yield: 0.016 g (57.8%). M.p.
>300 °C. Anal. Calc. for C96H106N8O12: C, 73.75; H,
6.79; N, 7.17. Found: C, 73.13; H, 6.53; N, 7.42%. FT-IR
(KBr), mmax/(cmꢀ1): 3290 (NH), 3074 (Ar–CH), 2926–
2858 (aliphatic CH), 1732 (C@O), 1595–1466 (Ar C@C),
1250 (Ar–O–Ar), 1165 (ester C–O), 1024, 941, 835, 748,
627 and 519.1H NMR (d-DMSO 500 MHz, d ppm):
8.21–6.75 (b, 28H, Ar–H), 4.11 (t, 8H, COOCH2R),
1.72–1.08 (m, 48H, COOCH2(CH2)6CH3), 0.89 (t, 12H,
CH3), ꢀ7.8 (br s, 2H, NH). MS (LC-MS, Scan ES+) m/z:
1562 [M+]. UV–Vis kmax(nm) (loge) in DMF: 320 (4.19),
619 (3.94), 644 (3.94), 681 (4.27).
2.2. Electrochemistry
The cyclic voltammetry, differential pulse voltammetry
and controlled potential chronocoulometry measurements
were carried out with a Princeton Applied Research Model
Versostat II potentiostat/galvanostat controlled by an
external PC and utilizing a three-electrode configuration
at 25 °C. The working electrode was a Pt plate with a sur-
face area of 0.10 cm2. The surface of the working electrode
was polished with a H2O suspension of Al2O3 before each
run. The last polishing was done with a particle size of
50 nm. A Pt wire served as the counter electrode. A satu-
rated calomel electrode (SCE) was employed as the refer-
ence electrode and separated from the bulk of the
solution by a double bridge. Ferrocene was used as an
internal reference. Electrochemical grade tetrabutylammo-
nium perchlorate (TBAP) in extra pure dimethylsulfoxide
(DMSO) was employed as the supporting electrolyte at a
concentration of 0.10 mol dmꢀ3. High purity N2 was used
for deoxygenating the solution for at least 20 min prior
to each run and to maintain a nitrogen blanket during
the measurements. For CPC studies, a Pt gauze working
electrode (10.5 cm2 surface area), Pt wire counter electrode
separated by a glass bridge and a SCE as a reference elec-
trode were used.
2.1.5.2. 2,9,16,23-Tetrakis(octyl 4-phenyloxyacetate)phtha-
locyaninatocobalt (II) (4a). This is soluble in THF,
CHCl3, CH2Cl2, DMF, DMSO and pyridine. Yield:
0.012 g (43%). M.p. >300 °C. Anal. Calc. for
C96H104N8O12Co: C, 71.15; H, 6.42; N, 6.92. Found: C,
71.85; H, 6.69; N, 6.56%. FT-IR (KBr), mmax/(cmꢀ1):
3056 (Ar–CH), 2926–2858 (aliphatic CH), 1736 (C@O),
1595–1458 (Ar C@C), 1246 (Ar–O–Ar), 1157-1101 (ester
C–O), 1020, 916, 835, 748, 667, 627 and 519. MS (LC-
MS, Scan ES+) m/z: 1619 [M+]. UV–Vis kmax (nm) (loge)
in DMF: 303 (4.83), 324 (4.82), 663 (4.75).
2.1.5.3. 2,9,16,23-Tetrakis(octyl 4-phenyloxyacetate)phtha-
locyaninatozinc (II) (4b). This is soluble in THF, CHCl3,
CH2Cl2, DMF, DMSO and pyridine. Yield: 0.015 g
(53%). M.p. >300 °C. Anal. Calc. for C96H104N8O12Zn:
C, 70.89; H, 6.40; N, 6.89. Found: C, 71.21; H, 6.54; N,
6.42%. FT-IR (KBr), mmax/(cmꢀ1): 3067 (Ar–CH), 2926–
2851 (aliphatic CH), 1728 (C@O), 1595–1462 (Ar C@C),
1250 (Ar–O–Ar), 1161–1101 (ester C–O), 1020, 972, 901,
839, 745, 683, 623 and 519. 1H NMR (d-DMSO
500 MHz, d ppm): 8.31–6.62 (b, 28H, Ar–H), 4.17 (t, 8H,
COOCH2R), 1.76–1.03 (m, 48H, COOCH2(CH2)6CH3),
0.86 (t, 12H, CH3). MS (LC-MS, Scan ES+) m/z: 1625
[M+]. UV–Vis kmax (nm) (loge) in DMF: 353 (4.70), 638
(4.59), 680 (4.92).
3. Results and discussion
3.1. Synthesis and characterization
p-(3,4-Dicyanophenoxy)phenylacetic acid (1) was
obtained by the base-catalyzed nucleophilic aromatic nitro
displacement of 4-nitrophthalonitrile with 4-hydroxyphe-
nylacetic acid (Scheme 1) [15,16]. The reaction was carried
out in a single-step synthesis using K2CO3 as the nitro-
displacing base at 50–60 °C in dry DMF under a N2
atmosphere. Conversion of 1 into the metal-free phthalo-
cyanine (2) is accomplished in a mixture of 1,2-dichloro-
benzene and pentanol in the presence of lithium [17].
Dilithium Pcs can be labile towards water and acid, and
can easily be converted to the metal-free phthalocyanine
(2). The metallophthalocyanines (2a–d) [M = Co(II),
2.1.5.4. 2,9,16,23-Tetrakis(octyl 4-phenyloxyacetate)phtha-
locyaninatonickel (II) (4c). This is soluble in THF, CHCl3,
CH2Cl2, DMF, DMSO and pyridine. Yield: 0.023 g (84%).
M.p. >300 °C. Anal. Calc. for C96H104N8O12Ni: C, 71.15;
H, 6.42; N, 6.92. Found: C, 71.68; H, 6.27; N, 7.11%.
FT-IR (KBr), mmax/(cmꢀ1): 3074 (Ar–CH), 2926–2858 (ali-
phatic CH), 1732 (C@O), 1595–1462 (Ar C@C), 1250 (Ar–
O–Ar), 1165–1113 (ester C–O), 1020, 988, 916, 845, 787,
1
748, 683, 627 and 527. H NMR (d-DMSO 500 MHz, d
ppm): 8.12–6.73 (b, 28H, Ar–H), 4.19 (t, 8H, COOCH2R),
1.72–1.05 (m, 48H, COOCH2(CH2)6CH3), 0.84 (t, 12H,

2642
M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
1) DMF
K CO , N
2
,
2
3
50-60 0
O2N
CN
CN
NC
NC
O
C
HO
CH2COOH
+
2) HCl
CH2COOH
1
4-Nitrophthalonitrile
4-Hydroxyphenylacetic acid
1) 1,2-Dichlorobenzene
Pentanol, Lithium
170 0
C, 3h
2) HCl
CH2COOH
CH2COOH
O
O
N
1) Metal salts, DMF, 155 0 C
N
N
N
N
N
N
N
2) HCl
N
N
O
CH2COOH
H
N
H
O
CH2COOH
HOOCCH2
O
O
N
M
N
HOOCH2C
N
N
N
2a M= Co
2b M= Zn
2c M= Ni
2d M= Cu
O
O
CH2COOH
CH2COOH
2a-d
2
Scheme 1. p-(3,4-Dicyanophenoxy)phenylacetic acid (1) and phthalocyanines derived from it.
Zn(II), Ni(II) and Cu(II)] were prepared from compound
2 and the corresponding metal salts [CoCl2 Æ 6H2O, Zn-
(AcO)2 Æ 2H2O, NiCl2 Æ 6H2O and CuCl2] in dimethylform-
amide [17]. Further reactions of these phthalocyanines (2,
2a–d) with thionylchloride and benzylamine in tetrahydro-
furan, and octanol in pyridine gave amide (3, 3a–d) and
ester (4, 4a–d) derivatives, respectively (Scheme 2) [18].
Formation of the amides and esters from the phenyloxy-
acetic acid groups of the phthalocyanine derivatives (2,
2a–d) was carried out in order to show the reactivity of
these side groups.
The four polar peripheral substituents conferred upon
these macromolecules (2, 2a–d, 3, 3a–d) good solubility in
polar solvents such as pyridine, DMF and DMSO. The
products (2, 2a–d, 3, 3a–d) were obtained in sufficient pur-
ity after successive washing with different solvents. The
ester derivatives (4, 4a–d) show good solubility in organic
solvents such as CHCl3, THF and CH2Cl2. The products
2 M=2H
SOCl
2a M= Co
2b M= Zn
2c M= Ni
2d M= Cu
,reflux
1)
,reflux
SOCl
1)
2
2
2) Pyridine, Octanol
2)THF, Benzylamine
O
CH
2
H2C
O
HN
H2C
O
O
O
H2
C
N
N
N
N
N
N
N
O
O
N
O
H2
C
H2
C
H
O
N
O
C
H2
N
M
C
H2
O
N
O
H
M
N
O
O
C
H2
N
N
N
O
N
N
N
O
3
M= 2H
4
M= 2H
O
3a M= Co
3b M= Zn
3c M= Ni
3d M= Cu
4a M= Co
4b M= Zn
4c M= Ni
4d M= Cu
O
CH
2
NH
O
CH
H2C
2
O
4, 4a-d
3, 3a-d
Scheme 2. Phthalocyanines bearing N-benzyl-4-phenyloxyacetamide and octyl 4-phenyloxyacetate moieties.

M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
2643
(4, 4a–d) were purified by silica gel column chromatogra-
phy with chloroform as the eluent.
and the NHCH2Ar protons as a doublet at d 4.31 ppm.
The phthalocyanines containing octyl 4-phenyloxyacetate
moieties (4, 4a–d) were confirmed by the disappearance
of the COOH band of 2, 2a–d at 3400–3500 cmꢀ1, and
the appearance of ester C–O bands at 1157–1101 cmꢀ1
and more intense aliphatic CH2 bands at 2926–
Characterization of the products involved a combina-
tion of methods including elemental analysis, FT-IR,
1
UV–Vis, mass and H NMR spectroscopy. The spectro-
scopic data of the new compounds were in accordance with
the structures.
1
2858 cmꢀ1. The H NMR spectrum of 4 showed the aro-
When the IR spectrum of 4-nitrophthalonitrile is com-
pared with that of 1, a distinct difference is the disappear-
ance of the aromatic –NO2 band at 1548 cmꢀ1 and the
appearance of a new absorption at 1246 cmꢀ1, attributable
to aromatic (C–O–C). In the IR spectrum of 1 the presence
of C„N and C@O groups is indicated by intense stretching
matic protons as a broad peak at d 8.21–6.75 and the
COOCH2R protons as a triplet at d 4.11 ppm. The –
CCH2C– protons in the long aliphatic chain appear at d
1.72–1.08 and the CH3 at the end of the chain as a triplet
at d 0.89 ppm.
The phthalocyanines 2, 2a–d, 3, 3a–d, 4 and 4a–d show
typical electronic spectra with two strong absorption
regions, one of them in the UV region at about 300–
350 nm (B band) and the other in the visible part of the
spectrum around 600–700 nm (Q band) [19]. The Q band
of all the compounds was attributed to the p ! p* transi-
tion from the highest occupied molecular orbital (HOMO)
to the lowest unoccupied molecular orbital (LUMO) of
the phthalocyanine (ꢀ2) ring [20,21]. The B band of all
1
bands at 2231 cmꢀ1 and 1703 cmꢀ1, respectively. The H
NMR spectrum of 1 in deuterated DMSO gave a singlet
at d 12.36 ppm (COOH), a singlet at d 3.63 ppm (CH2)
and the doublets at d 8.09–7.15 ppm correspond to aro-
matic protons. The 13C NMR spectrum of 1 indicated
nitrile carbons at d 116.61 and 116.09 ppm as expected.
Protonated aromatic and unsaturated carbon atoms
appeared in the range d 161.83–108.80 ppm. Also the car-
bon atom of carboxylic acid was observed at the lowest
field value at d 173.20 ppm.
the phthalocyanines arise from the deeper
p lev-
els ! LUMO transitions [20–22]. The electronic absorp-
tion spectrum of the metal-free phthalocyanine 2 exhibits
a partly split Q band absorption at 699 and 667 nm, that
of 3 at 704 and 682 nm and 4 at 681 and 644 nm. There is
a shoulder at the slightly higher energy side for each
phthalocyanine (2, 3 and 4) at 638 nm, 646 nm and
619 nm, respectively. The B band of these pcs appeared
in the UV region at 340 nm, 330 nm and 320 nm, respec-
tively. The metallo derivatives (2a–d, 3a–d and 4a–d) show
only an intense single Q band absorption for the p ! p*
transitions at around 660–680 nm with weaker absorp-
tions at around 609–620 nm. Weaker absorptions on the
higher energy side of the Q bands are generally observed
in the case of metallophthalocyanines, indicating the pres-
ence of aggregated species together with the monomeric
ones which are essentially responsible for the intense
absorption occurring in the main Q bands [2]. When the
electronic spectra of the metal-free phthalocyanine (2),
nickel and copper phthalocyanines (2c–d, 3c–d and 4c–d)
were carefully examined, a clear difference from the usual
phthalocyanines could be easily observed. The Q band of
2 was split into three peaks. The Q band of the nickel and
copper phthalocyanines was split into two peaks (Fig. 1).
At higher concentrations, the intensity of the higher
energy peak corresponding to aggregated species increased
while that of the monomeric ones at lower energy
decreased. At lower concentrations, the intensity of the
peak corresponding to monomeric species increased. ZnPc
(unsubstituted) dye is characterized by a band with a max-
imum at 673 nm as observed in the literature for ZnPc
[23]. The zinc metallophthalocyanines (2b, 3b, and 4b)
showed a bathochromic shift of 6 nm, 10 nm, 7 nm,
respectively. The B band absorptions of these pcs were
observed at 356 nm, 360 nm and 353 nm, respectively
(Fig. 2).
Cyclotetramerization of the dinitrile (1) into the phtha-
locyanine (2) was confirmed by the disappearance of the
sharp C„N vibration at 2231 cmꢀ1. The IR band charac-
teristic of the metal-free phthalocyanine ring is an N–H
stretching at 3290 cmꢀ1. The IR spectra of the metal-free
(2) and metallo (2a–d) phthalocyanines are very similar,
except the m(NH) vibrations of the inner phthalocyanine
core in the metal-free molecule. These protons are also
very well characterized by the 1H NMR spectra which
show a peak at d ꢀ7.22 ppm, ꢀ8.0 ppm and ꢀ7.80 ppm
for 2, 3 and 4, respectively, and the signals disappeared
1
after the addition of D2O. The H NMR spectrum of 2
indicates carboxylic acid protons (COOH) at
d
12.40 ppm as a singlet, aromatic protons at d 7.24–
6.02 ppm as a broad peak and aliphatic protons (CH2)
d 3.97 ppm as a singlet. 1H NMR measurements were
precluded owing to the paramagnetic nature of the cobalt
(II) phthalocyanines (2a, 3a and 4a) and copper (II) pht-
halocyanines (2d, 3d and 4d). The only difference between
the 1H NMR spectra of the metal-free phthalocyanines
(2, 3 and 4) and the metallo derivatives (2b, 2c, 3b, 3c,
4b and 4c) is the lack of broad chemical shifts of the
1
inner core NH protons. The H NMR spectra of the pht-
halocyanines are rather broad, owing probably to the
aggregation of the phthalocyanines which is frequently
encountered at the concentrations used for NMR spec-
troscopy [2].
Comparison of the IR spectral data indicated the forma-
tion of compounds 3, 3a–d by the disappearance of the
COOH band of compounds 2, 2a–d at 3400–3500 cmꢀ1
,
and the appearance of amide NH bands at 3290 and
1
1655 cmꢀ1. In the H NMR analysis of 3 in deuterated
DMSO, the aromatic protons appear as a broad peak at
d 7.63–7.11, the amide NH protons as a singlet at d 8.65

2644
M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
1.2
1
1.2
1
2a
a
0.8
0.8
0.6
0.4
0.2
0
b
2
0.6
c
d
0.4
e
0.2
0
280
380
480
580
680
780
280
380
480
580
680
780
Wavelength/nm
Wavelength/nm
1.11×10-5 M in DMF.
(a =1.62; b =1.44; c =1.08; d =0.72;
e =0.36)×10-5 M in DMF.
1.4
1.2
1
1.2
1
2b
0.8
0.8
0.6
0.4
0.2
0
a
b
c
d
e
2c
0.6
0.4
0.2
0
280
380
480
580
680
780
280
380
480
580
680
780
880
Wavelength/nm
Wavelength/nm
1.02×10-5 M in DMF.
(a =1.71; b =1.37; c =1.03; d =0.68;
e =0.34)×10-5 M in DMF.
0.4
0.3
0.2
0.1
0
a
b
c
d
2d
280
380
480
580
680
780
e
Wavelength/nm
(a =1.70; b =1.36; c =1.02; d =0.68;
e =0.34)×10-5 M in DMF.
Fig. 1. Changes in the electronic spectra of 2, 2a–d with different concentrations.
3.2. Electrochemistry
one-electron oxidation process labelled as O1 at 0.83 V
vs. SCE at 0.100 V sꢀ1 scan rate. Reduction and oxidation
redox processes, usually associated with the transfer of one
electron and thus the formation of anionic and cationic
radicals, occur only at the ligand in metal-free phthalocya-
nines and in some metallophthalocyanines involving a
redox-inactive metal center, while they occur both at the
metal center and at the phthalocyanine ring in those with
redox-active metal centers [6,24–30]. Thus, all the couples
of 2 are assigned undoubtedly to the phthalocyanine ring.
The ratio of the anodic to cathodic peak currents for these
couples are usually close to unity, suggesting reversible
redox processes. Anodic to cathodic peak separations
The solution redox properties of ligand 2 and its metal
complexes (2a–d) were studied using cyclic voltammetry,
differential pulse voltammetry and controlled potential
chronocoulometry in DMSO on a platinum electrode.
Voltammetric data and the assignment of the redox cou-
ples recorded for the ligand and its complexes are listed
in Table 1.
Fig. 3 shows the cyclic voltammogram of the metal-free
phthalocyanine 2 in DMSO containing TBAP. It gives
three one-electron reduction processes labelled as R1 at
ꢀ0.65 V, R2 at ꢀ0.96 V and R3 at ꢀ1.78 V, and a

M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
2645
1.4
1.2
1
30
30
20
R3
20
10
R3
R2
0.8
0.6
0.4
0.2
0
2b
R1
0
O1
3b
-10
10
0
4b
1.5 1.0 0.5 0.0 -0.5 -10 -1.5 -2.0 -2.5
E / V vs. SCE
R2
R1
O1
280
380
480
580
680
780
880
Wavelength/nm
-10
Fig. 2. Electronic spectra of 2b, 3b and 4b in DMF.
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
E / V vs. SCE
(DEp) changed from 0.050 to 0.160 V within the scan rates
from 0.010 to 0.500 V sꢀ1 (DEp changed from 0.060 to
0.140 V for ferrocene), providing additional support for a
reversible electron transfer. The peak currents increased
linearly with the square root of the scan rates for scan rates
ranging from 0.010 to 0.500 V sꢀ1, indicating purely diffu-
sion-controlled behavior [31].
Voltammetric studies revealed that the redox behaviour
of metallophthalocyanines 2b, 2c and 2d is very similar to
that of the metal-free phthalocyanine 2 (Table 1). The inset
in Fig. 3 exemplifies a typical cyclic voltammogram of 2c.
This similarity suggests that all the one-electron redox pro-
cesses of 2b, 2c and 2d are phthalocyanine ring based.
However, the redox potentials of these metallophthalocya-
Fig. 3. Cyclic voltammogram of 2 and 2c (inset) at 0.100 V sꢀ1 in TBAP/
DMSO.
nines occur usually at potentials slightly more negative as
compared to 2. The shift in the potentials can be attributed
to the polarizing effect of the M(II) ions. When we compare
the redox potentials of the phthalocyanines bearing four
4-phenyloxyacetic acid moieties with those of the relevant
unsubstituted phthalocyanines in the literature [24] it is
clear that the redox potentials of 2, 2a, 2b, 2c and 2d shift
to relatively more positive potentials, probably due to the
electron withdrawing effect of the phenyloxyacetic acid
substituents (Table 1). Reduction of the phthalocyanine
ligand is associated with the position of the LUMO,
whereas oxidation of the ligand is associated with the posi-
tion of the HOMO. Thus, the difference between the poten-
tials of the first oxidation and the first reduction processes
(DE1/2) reflects the HOMO–LUMO gap for the metal free
Pcs and it is closely related with the HOMO–LUMO gap in
MPc species involving the redox inactive metal center. The
DE1/2 values recorded for 2, 2b, 2c and 2d in this study are
in agreement with the values reported previously for the
relevant phthalocyanines [24].
The redox potential of 2a is considerably different as
compared with that of 2, 2b, 2c and 2d. Fig. 4 shows the
cyclic and differential pulse voltammograms of 2a in
DMSO containing TBAP. Within the electrochemical win-
dow of TBAP/DMSO, compound 2a undergoes a quasi-
reversible one-electron oxidation and two quasi-reversible
one-electron reductions at 0.45, ꢀ0.37 and ꢀ1.28 versus
SCE at 0.100 V sꢀ1 scan rate, respectively. The difference
in the voltammetric behaviour of 2a is due to the fact that
metallophthalocyanines such as MnPc, CoPc and FePc,
having a metal that possesses energy levels lying between
the HOMO and the LUMO of the phthalocyanine ligand,
in general exhibit redox processes centered on the metal
[24–26,28,29]. For CoPc complexes, the first oxidation
and first reduction processes occur on the metal center in
polar solvents such as DMF and DMSO, however the first
oxidation process occurs on the Pc ring in non-polar
solvents such as DCM and THF. Therefore, the first reduc-
tion and the first oxidation processes of 2a could be
Table 1
The electrochemical data of 2, 2a, 2b, 2c and 2d
Complex Redox
processes
E1/2 (V vs.
SCE)a
DEp
Ipa
/
c
DE1/2
(mV)b
Ipc
(V)d
2
R1
ꢀ0.65
ꢀ0.96
ꢀ1.78
0.83
0.070
0.080
0.160
0.060
0.96
0.98
e
1.48
R2
R3
O1
e
2a
2b
R1
R2
O1
ꢀ0.37
ꢀ1.28
0.45
0.100
0.080
0.100
1.00
0.95
0.94
0.82
1.44
R1
R2
R3
O1
ꢀ0.73
ꢀ1.06
ꢀ1.84
0.71
0.080
0.080
0.100
0.120
0.96
0.98
e
1.00
0.94
1.00
e
2c
2d
R1
R2
R3
O1
ꢀ0.72
ꢀ1.05
ꢀ1.84
0.73
0.080
0.090
0.120
0.140
1.45
1.45
0.98
0.94
1.00
e
R1
R2
R3
O1
ꢀ0.71
ꢀ1.06
ꢀ1.82
0.74
0.090
0.080
0.100
0.150
0.98
a
b
c
E1/2 = (Epa + Epc)/2 at 0.100 V sꢀ1
.
DEp = Epa ꢀ Epc at 0.100 V sꢀ1
.
Ipa/Ipc for reduction, Ipc/Ipa for oxidation processes at 0.100 V sꢀ1
.
d
DE1/2 = E1/2(first oxidation) ꢀ E1/2 (first reduction). This value reflects
the HOMO–LUMO gap for the ligand and its complexes, except 2a.
e
DEp could not be determined due to an ill-defined redox wave.

2646
M. C¸ amur et al. / Polyhedron 26 (2007) 2638–2646
[2] C.C. Leznoff, A.B.P. Lever, Phthalocyanines Properties and Appli-
cations, VCH, Weinheim, 1989.
6
4
[3] N. Kobayashi, Curr. Opin. Solid State Mater. Sci. 4 (1999) 345.
¨
R2
R1
O1
¨
[4] Sß. Abdurrahmanog˘lu, A. Altındal, A.R. Ozkaya, M. Bulut, O.
Bekarog˘lu, Chem. Commun. (2004) 2029.
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[5] Sß. Abdurrahmanog˘lu, A.R. Ozkaya, M. Bulut, O. Bekarog˘lu,
0,5 0,0 -0,5 -1,0 -1,5
2
E / V versus SCE
J. Chem. Soc., Dalton Trans. (2004) 4022.
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R2
¨
¨
¨
R1
0
¨
O1
[7] M. Kandaz, H.S. C¸ etin, A. Koca, A.R: Ozkaya, Dyes Pigm,
25 mVs-1
50 mVs-1
100 mVs-1
doi:10.1016/j.dyepig.2006.02.008, in press (2006).
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-4
¨
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(2005) 6057.
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0.5
0.0
-0.5
-1.0
-1.5
-2.0
E / V versus SCE
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Fig. 4. Cyclic and differential pulse voltammograms of 2a in TBAP/
DMSO.
¨
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[Co(II)Pc(ꢀ2)]/[Co(III)Pc(ꢀ2)]+ redox couples and the sec-
ond reduction process to the phthalocyanine ring as
[Co(I)Pc(ꢀ2)]ꢀ/[Co(I)Pc(ꢀ3)]2ꢀ. The separation between
the first oxidation and the first reduction potentials of the
metal center (ꢁ0.82 V) is comparable with the relevant val-
ues in the literature [24–26,28,29], and does not reflect the
HOMO–LUMO gap.
In conclusion, we have described the synthesis and spec-
tral characterization of some new phthalocyanines with 4-
phenyloxyacetic acid, N-benzyl-4-phenyloxyacetamide and
octyl 4-phenyloxyacetate substituents on the periphery.
Cyclic voltammetry of these compounds is also presented.
Esterification of carboxy groups brings forward more solu-
ble products in less polar solvents such as chloroform,
THF and dichloromethane.
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¨
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Acknowledgements
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¨
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