Microwave-assisted synthesis and characterization and theoretical calculations of the first example of free and metallophthalocyanines from salen type Schiff base derivative bearing thiophen and triazole heterocyclic rings

Article abstract of DOI:10.1016/j.jorganchem.2007.09.026

Novel metal-free and metallophthalocyanine complexes of Co, Ni, Cu, and Zn have been synthesized by exposure to microwave irradiation and reflux conditions and the products purified by several techniques. The newly prepared compounds have been characteriz

Full text of DOI:10.1016/j.jorganchem.2007.09.026

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 692 (2007) 5646–5654
www.elsevier.com/locate/jorganchem
Microwave-assisted synthesis and characterization and
theoretical calculations of the first example of free and
metallophthalocyanines from salen type Schiff base derivative
bearing thiophen and triazole heterocyclic rings
a,
b
b
b
_
*
¨
˘
˘
Kerim Serbest , Ismail Degirmencioglu , Yasemin Unver , Mustafa Er ,
a
b
Cihan Kantar , Kemal Sancak
a
Department of Chemistry, Faculty of Arts and Sciences, Rize University, 53050 Rize, Turkey
Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
b
Received 26 June 2007; received in revised form 25 August 2007; accepted 24 September 2007
Available online 1 October 2007
Abstract
Novel metal-free and metallophthalocyanine complexes of Co, Ni, Cu, and Zn have been synthesized by exposure to microwave irra-
diation and reflux conditions and the products purified by several techniques. The newly prepared compounds have been characterized
1
by elemental analyses, IR, H NMR, MS and UV–Vis spectroscopy. Furthermore, theoretical calculations of metallophthalocyanines
CuPc, NiPc, ZnPc and CoPc were carried out to comparatively describe the molecular structures, molecular orbital and UV–Vis spectra
of metallophthalocyanine complexes by the HF theory. A comparison between the different molecules for the geometry, molecular orbi-
tals was made. The simulated order of the sizes of the central hole was CoPc > NiPc < CuPc < ZnPc, which is in complete accord with
the experiment. Moreover, the HOMO–LUMO gaps were varied in order of CoPc > NiPc > ZnPc > CuPc. The calculated structures,
electronic absorption spectra of metallophthalocyanine complexes are in good consistency with the experimental results.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Phthalocyanine; Complexes; Schiff base; UV–Vis; Microwave-assisted
1. Introduction
(PDT) cancer therapy [11,12], photoconductors in xerogra-
phy [13], dyes at recording layers for CD-R and DVD-R
optical storage discs [14], as well as diverse catalytic sys-
tems [15,16].
Phthalocyanines form nowadays an important group of
organic compounds that belongs to the most studied sub-
jects of organic functional materials [1]. The most impor-
tant industrial application of phthalocyanines is the
formation of color complexes with metal cations that are
used as highly stable pigments and dyes [2]. In addition,
they can find commercial applications as: photovoltaic
materials in solar cells [3–5], systems for fabrication of light
emitting diodes (LED) [6,7], liquid crystalline [8] and non-
linear optical materials [9,10], sensitizers for photodynamic
Phthalocyanines are usually prepared by the high tem-
perature cyclotetramerization processes of either phthalo-
nitrile (1) or phthalic anhydride (2), in which the template
effect afforded by a suitable metal cation is required
(Scheme 1). The reactions can be carried out in variety
of solvents as well as under solvent-free conditions, but
both processes require temperature ca. 200 °C and long
reaction times [1]. It is well known that microwave
(MW) irradiation can accelerate a great number of chem-
ical processes, and, in particular, the reaction time and
energy input are supposed to be mostly reduced in the
*
Corresponding author. Tel.: +90 464 2236126; fax: +90 464 2235376.
E-mail address: kerimserbest@yahoo.com (K. Serbest).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.09.026

K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
5647
N
N
O
N
O
CN
CN
MX
MX
N
M
N
O
NH2
H2N
N
O
N
N
(2)
(1)
MX: CuCl2, NiCl2, CoCl2 or ZnCl2
Scheme 1. Synthesis of phthalocyanines from phthalonitrile (1) or phthalic anhydride (2) and urea.
reactions that are run for a long time at high tempera-
2.1. 4-{[(1E)-(2-Hydroxyphenyl)methylene]amino}-5-
(2-thienylmethyl)-2,4- dihydro-3H-1,2,4-triazol-3-one (2)
tures under conventional conditions [17]. Thus, we have
decided to apply microwave irradiation for the synthesis
of phthalocyanine in order to check whether such non-
classical method of chemical activation might influence
yield, selectivity and time of reaction in comparison with
a conventional thermal treatment under strictly similar
sets of conditions.
In this study, the first example of the phthalocyanines
with four salen type Schiff base with triazole and thio-
phen ring substituents were prepared by conventional
and microwave methods. Furthermore, theoretical calcu-
lations of metallophthalocyanines CuPc, NiPc, ZnPc and
CoPc were carried out to comparatively describe the
molecular structures, molecular orbital and UV–Vis
spectra of metallophthalocyanine complexes by the HF
theory.
4-Amino-5-(2-thienylmethyl)-2,4-dihydro-3H-1,2,4-tria-
zol-3-one (1) (1.96 g, 10 mmol) and salicylaldehyde
(1.05 ml, 10 mmol) was mixed without solvent and care-
fully heated at 135–140 °C for 2 h under N2. The formed
solid products were separated by filtration, purified by
crystallization twice from dry ethanol, washed with diethyl
ether and dried in a vacuum over P2O5. Yield: 2.40 g,
(80%), mp: 190–192 °C. Anal. Calc. for C14H12N4O2S: C,
55.99; H, 4.03; N, 18.65. Found: C, 55.87; H, 3.86; N,
18.78%. IR (KBr tablet) mmax/cmꢀ1: 3166 (–NH), 3045
(Ar-CH), 1711 (C@O), 1618 (CH@N). 1H NMR.
(DMSO-d6), (d: ppm): 12.03 (s, 1H, NH), 10.30 (s, 1H,
OH), 9.98 (s, 1H, CH@N), 7.88–7.84 (m, 1H, Ar-H3),
7.47–7.31 (m, 2H, Ar-H14,17), 7.03–6.89 (m, 4H, Ar-
H
15,16,1,2), 4.28 (s, 2H, CH2). 13C NMR. (DMSO-d6), (d:
2. Experimental
ppm): 158.28 (C@O), 151.86 (CH@N), 151.22, 146.21
(C@N), 138.14, 133.62, 127.59, 127.27, 126.94, 126.01,
120.29, 120.22, 117.10, 26.44 (CH2). MS (ESI), (m/z):
300.52 [M]+.
All reactions were carried out under an atmosphere of
dry, oxygen-free nitrogen, using standard Schlenk tech-
niques. All solvents were dried and purified as described
by Perrin and Armarego [18]. H NMR and 13C NMR
2.2. 4-[2-((E)-{[5-Oxo-3-(2-thienylmethyl)-1,5-dihydro-
4H-1,2,4- triazol-4-yl]imino} methyl) phenoxy]
phthalonitrile (3)
1
spectra were recorded on a Varian XL-200 NMR spectro-
photometer in DMSO-d6, and chemical shifts were
reported (d) relative to Me4Si as internal standard. IR
spectra were recorded on a Perkin–Elmer Spectrum one
FT-IR spectrometer in KBr pellets. The MS spectra were
measured with a Micromass Quattro LC/ULTIMA LC-
MS/MS spectrometer equipped with pyridine–methanol
as solvent. All experiments were performed in the positive
ion mode. Elemental analyses were performed on a
LECO Elemental Analyser (CHNS O932); their values
agreed with the calculated ones. UV–Vis spectra were
recorded by means of a Unicam UV2-100 spectropho-
tometer, using 1 cm pathlength cuvettes at room temper-
ature. Beko MD 1500, 2.45 MHz domestic microwave
oven, was used in all synthesis of phthalocyanines. Melt-
ing points were measured on an electrothermal apparatus
and are uncorrected.
Compound (2) (0.50 g, 1.66 mmol), 4-nitrophthalonitrile
(2a) (0.29 g, 1.66 mmol), finely ground anhydrous K2CO3
(0.45 g, 3.32 mmol) and dry dimethylformamide (5 ml)
were also irradiated in a microwave oven at 360 W for
5 min. At the end of reaction, DMF mixture was added
to 250 ml of a cold HCl (5 wt.%) solution to yield a crude
product. This precipitate was stirred at room temperature
for 24 h. The precipitate was isolated by filtration and
was first washed with distilled water, until the filtrate was
neutral, and then diethyl ether before drying in vacuo over
P2O5. Recrystallization from hot ethanol gave a light
brown product. Yield: 0.60 g, (85%), mp: 186 °C. Anal.
Calc. for C22H14N6O2S: C, 61.96; H, 3.31; N, 19.71.
Found: C, 62.02; H, 3.32; N, 19.68%. IR (KBr tablet)

5648
K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
m
max/cmꢀ1: 3110 (–NH), 3076 (Ar-CH), 2230 (C„N), 1706
Anal. Calc. for C88H56N24O8S4Cu:C, 59.74; H, 3.19; N,
19.00; Cu, 3.59. Found: C, 59.46; H, 3.34; N, 18.68; Cu,
3.81%. IR (KBr tablet) mmax/cmꢀ1: 3393 (–NHtriazole),
3097 (Ar-H), 2923 (Aliphatic-H), 1717 (C@O), 1600
(CH@N + C@C), 1471 (–CH2), 1450 (CH2–S–C), 1352
(C–N), 1270, 1231, 1097 (C–O–C), 1227 (CH2-S), 946
(–NH), 845 (C–O–C + NH). UV–Vis (pyridine):
1
(C@O), 1596 (CH@N). H NMR. (DMSO-d6), (d: ppm):
12.06 (s, 1H, NH), 9.90 (s, 1H, CH@N), 8.15–8.11 (d,
2H, Ar-H14,24), 7.92 (d, 1H, Ar-H3), 7.60 (dd, 2H, Ar-
H21,25), 7.46–7.38 (m, 2H, Ar-H15,16), 7.22 (d, 1H, Ar-
H17), 7.01–6.94 (m, 2H, Ar-H1,2), 4.23 (s, 2H, CH2). 13C
NMR. (DMSO-d6), (d: ppm): 160.56, 153.17 (C@O),
150.89 (CH@N), 147.09 (C@N), 145.40, 137.13, 136.33,
133.51, 127.10, 126.82, 126.53, 126.23, 125.33, 125.23,
122.92, 122.29, 121.04, 116.74, 115.69 (C„N), 115.19
(C„N), 108.77, 25.41 (CH2). MS (ESI), (m/z): 493.4
[M+C2H6O+Naꢀ2]+.
k
max/nm: [(10ꢀ4 e dm3 molꢀ1 cmꢀ1)]: 225 (5.01), 288
(4.90), 323 (4.89), 617 (4.43), 686 (5.06). MS (ESI), (m/
z): 1771.30 [M+1]+.
2.4.2. Method B
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous CuCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was heated to 145–150 °C under N2 and held at that tem-
perature for 48 h. After cooling to room temperature, it
was diluted with hot ethanol (ca. 30 ml) and stirred for
12 h. The product was filtered and then washed with
hot ethanol, water, and diethyl ether. Yield: 0.10 g,
(29.2%).
2.3. Metal-free phthalocyanine (4)
A standard Schlenk tube was charged with (0.25 g,
0.59 mmol) of (3), 2 ml of dry n-hexanol and (0.09 ml,
0.59 mmol) of 1,8-diazabiscyclo[5.4.0]undec-7-en (DBU)
under a nitrogen atmosphere and degassed several times.
The temperature was gradually increased up to 90 °C
and the flask was degassed again with nitrogen. Then
the reaction mixture was stirred at 145–150 °C for 36 h.
After the reaction mixture was cooled and evaporated
to dryness. The remaining dark green solid was stirred
with 25 ml diethyl ether and filtered. Finally, the raw
green product was refluxed with dry THF in soxlet
equipment for 3 days to give the light green yield. Yield:
0.14 g, (54%), mp: 226–229 °C. Anal. Calc. for
C88H58N24O8S4: C, 61.89; H, 3.42; N, 19.68. Found: C,
2.5. Nickel(II) phthalocyanine (6)
2.5.1. Method A
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous NiCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was irradiated in a microwave oven at 175 °C, 600 W for
8 min. Then it was diluted with hot ethanol (ca. 30 ml)
and stirred for 12 h. The product was filtered and then
washed with hot ethanol, water, diethyl ether, and dried
in vacuo. The solid product was chromatographed on silica
gel with chloroform/methanol (1:0.1) as eluents to give
dark green yield. The yield was more than in Method B.
Yield: 0.18 g, (52.7%), mp > 300 °C. Anal. Calc. for
C88H56N24O8S4Ni: C, 59.90; H, 3.20; N, 19.03; Ni, 3.33.
Found: C, 59.61; H, 3.12; N, 18.89; Ni, 3.54%. IR (KBr
tablet) mmax/cmꢀ1: 3392 (–NHtriazole), 3093 (Ar-H), 2923
(Aliphatic-H), 1719 (C@O), 1598 (CH@N + C@C), 1473
(–CH2), 1450 (CH2–S–C), 1354 (C–N), 1264, 1235,
1071 (C–O–C), 1223 (CH2–S), 953 (–NH), 842
61.74; H, 3.28; N, 19.86%. IR (KBr tablet) mmax/cmꢀ1
:
3230–3219 (–NHtriazole + –NHpc), 3055 (Ar-CH), 2919
(Aliphatic-CH), 1711 (C@O), 1598 (CH@N). 1H NMR.
(DMSO-d6), (d: ppm): 11.98 (br s, 4H, NH), 9.98
(s, 4H, CH@N), 8.1–7.61 (m, 12H, Ar-Hthiophene),
7.38–6.53 (m, 28H, Ar-H), 4.24 (s, 8H, CH2), ꢀ7.16 (s,
2H, –NHpc). 13C NMR. (DMSO-d6), (d: ppm): 186.5,
162.33 (C@O), 157.55 (CH@N), 148.02 (C@N), 142.43,
139.11, 137.05, 135.99, 132.27, 129.47, 129.39, 126.83,
126.82, 126.2, 124.39, 124.12, 123.38, 123.11, 122.11,
121.50, 121.44, 115.5, 28.25 (CH2). UV–Vis (pyridine):
k
max/nm: [(10ꢀ5 e dm3 molꢀ1 cmꢀ1)]: 269 (4.78), 290
1
(C–O–C + NH). H NMR. (DMSO-d6), (d: ppm): 11.91
(4.76), 305 (5.10), 668 (5.03), 705 (5.06) MS (ESI),
(br s, 4H, NHtriazole), 9.89 (s, 4H, CH@N), 8.41–6.99 (m,
(m/z): 1708.50 [M+1]+.
40H, Ar-Hthiophene and Ar-H), 3.93 (s, 8H, CH2). UV–Vis
(pyridine):
(4.95), 253 (5.02), 287 (4.93), 315 (5.90), 613 (4.34),
k
max/nm: [(10ꢀ4 e dm3 molꢀ1 cmꢀ1)]: 231
2.4. Copper(II) phthalocyanine (5)
681
(5.12).
MS
(ESI),
(m/z):
597.48
2.4.1. Method A
[M+Na+1ꢀC56H40N16O8S4]+.
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous CuCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was irradiated in a microwave oven at 175 °C, 600 W
for 8 min. Then it was diluted with hot ethanol (ca.
30 ml) and stirred for 12 h. The product was filtered
and then washed with hot ethanol, water, diethyl ether,
and dried in vacuo. The solid product was chromato-
graphed on silica gel with chloroform/methanol (1:0.1)
as eluents to give dark green yield. The yield was more
than in Method B. Yield: 0.14 g, (40.9%), mp > 300 °C.
2.5.2. Method B
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous NiCl2 (0.05 g, 0.387 mmol) and dry DMAE (2 ml)
was heated to 145–150 °C under N2 and held at that tem-
perature for 48 h. After cooling to room temperature, it
was diluted with hot ethanol (ca. 30 ml) and stirred for
12 h. The product was filtered and then washed with hot
ethanol, water, and diethyl ether. Yield: 0.13 g, (38.1%).

K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
5649
2.6. Zinc(II) phthalocyanine (7)
2.7.2. Method B
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous CoCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was heated to 145–150 °C under N2 and held at that tem-
perature for 60 h. After cooling to room temperature, it
was diluted with hot ethanol (ca. 30 ml) and stirred for
12 h. The product was filtered and then washed with hot
ethanol, water, and diethyl ether. Yield: 0.07 g, (20.5%).
2.6.1. Method A
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous ZnCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was irradiated in a microwave oven at 160 °C, 360 W for
4 min. Then it was diluted with hot ethanol (ca. 30 ml)
and stirred for 12 h. The product was filtered and then
washed with hot ethanol, water, diethyl ether, and dried
in vacuo. The solid product was chromatographed on silica
gel with chloroform/methanol (1:0.1) as eluents to give
dark green yield. The yield was more than in Method B.
Yield: 0.19 g, (55.4%), mp > 300 °C. Anal. Calc. for
C88H56N24O8S4Zn: C, 59.67; H, 3.19; N, 18.98; Zn, 3.69.
Found: C, 59.38; H, 3.26; N, 18.71; Zn, 3.98%. IR (KBr
tablet) mmax/cmꢀ1: 3390 (–NHtriazole), 3087 (Ar-H), 2925
(Aliphatic-H), 1711 (C@O), 1600 (CH@N + C@C), 1478
(–CH2), 1446 (CH2–S–C), 1316 (C–N), 1241, 1236,
1179 (C–O–C), 1221 (CH2–S), 943 (–NH), 834
3. Results and discussion
The preparation of Schiff bases (2), (3), the target metal-
free (4) and metallophthalocyanines (5, 6, 7) and (8) are
shown in Scheme 1. The structures of novel compounds
were characterized by a combination of 1H/13C NMR,
IR, UV–Vis, elemental analysis and MS spectral data.
4-Amino-5-(2-thienylmethyl)-2,4-dihydro-3H-1,2,4-triazol-
3-one (1) was prepared from the reaction of hydrazine
hydrate to the N0-(1-ethoxy-2-thiophene-2-yl-ethlydene)-
hydrazine carbocyclic acid ethyl ester in 1:1 ratio for 6 h
[19] (Scheme 2).
The condensation of (1) with salicylaldehyde at 1:1 ratio
was gave the salicylic Schiff base (2) in a high yield-(80.1%)
[19]. In the IR spectrum of (2), the intense absorption
bands at 3316–3218 cmꢀ1, corresponding to the –NH2
groups, disappear after the conversation to salicylaldehyde
and appear a new band at 1645 cmꢀ1 corresponding to
C@N group, indicating that the combining has occured.
The rest of the spectra of (2) resembles closely that of (1)
and (1a) including the characteristic vibration of aliphatic,
thiophene and phenolic groups. 1H NMR spectra of (2) are
almost identical, with only small changes in shifts. The dif-
ference between the two spectra of substituted amine (1)
and Schiff base (2) is clear from the presence of iminic car-
bon –CH@N at 9.98 ppm. 13C NMR spectra of (2) clearly
indicates the presence of C@O, CH@N and C@N group
bands at 158.28, 151.86 and 146.21 ppm, and the others
(aliphatic and aromatic carbons), respectively. The MS
mass spectrum of (2) shows a molecular ion peak at m/
z = 300.52 [M]+, supporting the proposed formula for this
compound.
1
(C–O–C + NH). H NMR. (DMSO-d6), (d: ppm): 11.93
(br s, 4H, NH), 9.66 (s, 4H, CH@N), 8.85–6.68 (m, 40H,
Ar-Hthiophene and Ar-H), 3.44 (s, 8H, CH2). UV–Vis (pyri-
dine): kmax/nm: [(10ꢀ4 e dm3 molꢀ1 cmꢀ1)]: 247 (5.00), 298
(5.07), 345 (4.87), 607 (4.49), 685 (5.13). MS (ESI), (m/z):
1795.78 [M+Na]+.
2.6.2. Method B
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous ZnCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was heated to 145–150 °C under N2 and held at that tem-
perature for 24 h. After cooling to room temperature, it
was diluted with hot ethanol (ca. 30 ml) and stirred for
12 h. The product was filtered and then washed with hot
ethanol, water, and diethyl ether. Yield: 0.15 g, (43.7%).
2.7. Cobalt(II) phthalocyanine (8)
2.7.1. Method A
A mixture of compound (3) (0.33 g, 0.77 mmol), anhy-
drous CoCl2 (0.05 g, 0.39 mmol) and dry DMAE (2 ml)
was irradiated in a microwave oven at 175 °C, 600 W for
15 min. Then it was diluted with hot ethanol (ca. 30 ml)
and stirred for 12 h. The product was filtered and then
washed with hot ethanol, water, diethyl ether, and dried
in vacuo. The solid product was chromatographed on silica
gel with chloroform/methanol (1:0.1) as eluents to give
dark green yield. The yield was more than in Method B.
Yield: 0.11 g, (32%), mp > 300 °C. Anal. Calc. for
C88H56N24O8S4Co: C, 59.89; H, 3.20; N, 19.05; Co, 3.34.
Found: C, 59.81; H, 3.08; N, 18.81; Co, 3.51%. IR (KBr
tablet) mmax/cmꢀ1: 3394 (–NHtriazole), 3088 (Ar-H), 2923
(Aliphatic-H), 1720 (C@O), 1600 (CH@N + C@C), 1479
(–CH2), 1450 (CH2–S–C), 1354 (C–N), 1244, 1233,
1152 (C–O–C), 1220 (CH2–S), 952 (–NH), 845
(C–O–C + NH). UV–Vis (pyridine): kmax/nm: [(10ꢀ4 e dm3
molꢀ1 cmꢀ1)]: 256 (4.90), 284 (5.07), 307 (4.81), 604 (4.34),
670 (4.99). MS (ESI), (m/z): 1765.01 [M+1]+.
The compound (3) was obtained from the reaction of (2)
to 4-nitrophthalonitrile (2a) in dry K2CO3/dry DMF under
Microwave oven atmosphere at room temperature, 360 W
for 5 min. These were accomplished by a base catalyzed
nucleophilic aromatic nitro displacement of 4-nitrophthalo-
nitrile with (2) [20,21]. Similarly, Comparison of the IR spec-
tral data clearly indicated the formation of compound (3)
by the disappearance of the O–H band of (2) at 3590
zand 1352 cmꢀ1 and of NO2 band of (2a) at 1519 and
1333 cmꢀ1, and the appearance of a new absorption at
1
2230 cmꢀ1 (C„N). H NMR spectra of (3) showed a new
signal due to iminic carbon (–CH@N) at d = 9.90 ppm, as
expected. While the 1H NMR spectra of (2) and (3) are sim-
ilar, the proton-decoupled 13C NMR spectrum indicated the
presence of nitrile carbon atoms in (3) at d = 115.69 and
115.19 ppm, respectively. Inaddition, the MS mass spectrum

5650
K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
N
N
N
N
O
NH
S
S
N
NH
N
+
+
N
H2N
O
N+
O
O
OH
O
(2)
(2a)
(1)
(1a)
OH
3
N
4
6
2
1
NH
5
S
N
9
O
N
12
14
24
13
17
25
N
23
22
15
20
O
18
16
21
(3)
N
S
N
N
N
NH
N
NH
O
O
N
O
S
N
M= 2H
(4)
M= Cu(II) (5)
M= Ni(II) (6)
M= Zn(II) (7)
M= Co(II) (8)
N
O
N
N
N
M
N
N
N
O
N
N
N
S
O
O
O
N
NH
NH
N
N
N
S
Scheme 2. The synthesis of metal-free and metallophthalocyanines.
of (3) shows a molecular ion peak at m/z = 493.4
[M+C2H6O+Naꢀ2]+, supporting the proposed formula
for this compound.
The metal-free derivative (H2Pc) (4) was obtained
directly by the reaction of substituted phthalonitrile (3)
with dry n-hexanol and DBU (1,8-diazabicy-
clo[5.4.0]undec-7-ene) [22].
Cyclotetramerization of phthalonitrile based on thio-
phene (3) in the presence of metal salts by two different
methods gave the metal phthalocyanines (5, 6, 7) and (8)

K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
5651
[23,24]. The solvent for conventional method was DMAE
(N,N-dimethylaminoethanol) for all metal salts. In addi-
tion, in the microwave-assisted method, the reactions of
(5, 6, 7) and (8) were accomplished in DMAE at 600 W
for 8 min for Cu(II) and Ni(II), 360 W for 4 min for Zn(II)
and 600 W for 15 min for Co(II). The solubility of the
phthalocyanines was low in common organic solvents such
as ethyl acetate, acetone, tetrahydrofurane, ethanol DMF.
The IR spectrum of metal-free phthalocyanine (4) shows
two different –NH bands (inner –NH and triazolic –NH) at
3230–3219 cmꢀ1. The rest of spectrum of (4) is exactly sim-
ilar that (3) except for C„N group in (3). The inner core –
NH protons of metal-free phthalocyanine (4) were also
Fig 1. UV–Vis spectra of compounds (4) and (6) in pyridine; (a)
corresponds to H2Pc and (b) corresponds to NiPc.
1
identified in the H NMR spectrum. Interestingly, at high
concentration strong shielding of the cavity protons in the
phthalocyanine core of this compound was indicated by a
single sharp resonance at d = ꢀ7.16 ppm, while be expected
to a broad resonance [25] which could be attributed to the
inner –NH resonance. The signals related to aromatic and
aliphatic protons in the macrocyclic moieties and phthalo-
cyanine skeleton gave significant absorbance characteristic
of the proposed structure. The MS mass spectrum of (4)
shows a molecular ion peak at m/z = 1708.50 [M+1]+, sup-
porting the proposed formula for this compound.
The metallophthalocyanines (5, 6, 7) and (8) were
obtained from dicyano derivative (3) and corresponding
anhydrous metal salts CuCl2, NiCl2, ZnCl2 and CoCl2,
respectively, both microwave irradiation in DMAE for
4–15 min and in a sealed tube in DMAE for 24–60 h. In
the IR spectra of all metallophthalocyanines, the disap-
pearance of strong C„N stretching vibration of (3) and
of inner –NH band at ca. 3219 cmꢀ1 is an evidence for
the formation of Metal-Pcs (5, 6, 7) and (8). Also, in the
1H NMR spectrum of metallophthalocyanines (6) and (7)
in DMSO-d6, the peak at d = 11.98 ppm for Ni(II) and at
d = 11.93 ppm for Zn(II) pertaining to triazolic –NH was
found, confirmed that this observation is accurate. In the
mass spectrum of compounds (5, 6, 7) and (8), the molecu-
lar ion peaks were observed at m/z = 1771.30 [M+1]+ for
Cu(II), 597.48 [M+Na+1ꢀC56H40N16O8S4]+ for Ni(II),
1795.78 [M+Na]+ for Zn(II) and 1765.03 [M+1]+ for
Co(II), confirmed the proposed structure.
the Q band which is shifted to shorter wavelengths, and to
a decrease in molar absorption coefficient [31–33].
The UV–Vis absorption spectra of metallophthalocya-
nines (5, 6, 7) and (8) are given in Figs. 1 and 2. These com-
pounds showed the expected absorptions at the main peaks
of the Q and B bands appearing at k = 686, 617 nm and
323, 288 and 225 nm for Cu(II), 681, 613 nm and 315,
287, 253 and 231 nm for Ni(II), 685, 607 nm and 345,
298 and 247 nm for Zn(II), and 670, 604 nm and 307, 284
and 256 nm for Co(II), respectively. This result is typical
of metal complexes of substituted and unsubstituted Pc
with D4h symmetry [2,34].
4. Computational method
In our calculations, for the geometry optimizations, we
employed the restricted Hartree–Fock (RHF) method, as
coded in HYPERCHEM 7.5 program running on an Intel Pen-
tium D inside cluster. Basis sets used for all calculations
were 6-31G(d) for C, S, N and O. The input structures of
the complexes were optimized using MM+ method [35].
If the optimized geometry was found to have different con-
formation, from that in which it coordinates to a metal ion,
In general, phthalocyanines show typical electronic
spectra with two strong absorption regions, one in the
UV region at ca. 300–500 nm related to the B band and
the other in the visible region at ca. 600–750 nm related
to the Q band [26]. The Q band absorptions of (4) in pyr-
idine at k = 705 and 668 nm and the other absorptions (as
known B) at 305, 290 and 269 nm are consistent with the
results obtained previously known phthalocyanines
[27–29], and which have been ascribed to the deeper
p!p* levels of LUMO transitions (Fig. 1). The Q band
absorption present in (4) can be attributed to the fact that
the symmetry of metal-free phthalocyanine is nondegener-
ate (D2h) and is split in a Qx and a Qy peak as shown in the
spectrum [30]. Also, an increase in the concentration leads
to aggregation which is easily monitored by the position of
Fig 2. UV–Vis spectra of compounds (5), (7) and (8) in pyridine; (a)
corresponds to CuPc, (b) corresponds to ZnPc, and (c) corresponds to
CoPc.

5652
K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
some of the torsion angles were appropriately modified to
obtain the correct conformation, corresponding to the
coordination mode and then the geometry optimizations
were made using the ZINDO/S method for MPc [35]. Fur-
thermore, the single point calculations at HF level were
carried out on all structures [36,37].
4.2. Electronic structures and molecular orbitals
The energies of the molecular orbitals from HOMO ꢀ 5
to LUMO + 3 of the four derivatives are shown in Table 2,
and also the pictures of HOMO–LUMO orbitals of all
metallophthalocyanines are shown in Figs. 3a and 3b.
The calculated energies of the molecular orbitals are exhib-
ited to five numbers after decimal point at the most with
the output file; however, four numbers after decimal point
reserved are enough to be compared one after another.
This is the reason why the energies of the molecular orbi-
tals are kept four numbers after decimal points.
On the basis of our calculation, the energy of the HOMO
and the LUMO are both negative for the four compounds.
For the four compounds, the maximum of the HOMO cor-
responds to CoPc, while minimum of the LUMO corre-
sponds to CuPc and are ꢀ5.7152 for Co(II) and 3.1709 eV
for Cu(II). Hence, CuPc has the minimum of the
HOMO–LUMO gaps, 1.9444 eV, which indicates that the
Q bands of CuPc should shift to the longest wavelength
side. This is because that the position of the Q band has
the relation with the HOMO–LUMO gap. The bigger the
value of the HOMO–LUMO gap is, the shorter the wave-
length of the Q band shifts to. The other HOMO–LUMO
gaps for NiPc, ZnPc and CoPc are 2.1056, 1.9692 and
2.1122 eV, respectively. These exhibit that the HOMO–
LUMO gaps vary in order of CuPc < ZnPc < NiPc < CoPc,
hence the variation of the Q bands ought to follow the
trend, CuPc > ZnPc > NiPc > CoPc. The experimental
results reveal that the position of Q-band in the electronic
spectra about accords with the theoretical ones [36]. Addi-
tionally, for all metallophthalocyanines, the Q bands at
4.1. Molecular structures
The single point energy-minimized structures calculated
at HF/6-31(d) level is D4h symmetry for MPc. It is worth
pointing out that no imaginary vibration is predicted in
the following frequency calculations, indicating that the
energy-minimized structures are true energy minima.
As listed in Table 1, the X-ray crystal parameters for
CuPc [38], NiPc [39], ZnPc [40] and CoPc [41] are almost
in agreement with the calculated data.
Analysis of the calculated structural parameters for
CuPc, NiPc, ZnPc and CoPc shows that the sizes of the
central holes (N–N distance) are, 3.88920 3.79519,
˚
3.96765 and 3.83584 A, respectively. That is to say, the
order of the sizes of the central hole is CoPc > NiPc
< CuPc < ZnPc. It is noteworthy that this pattern is in
complete accord with the variation of octahedral M2+ ions
radii suggested by Shannon [42] and discussed by Hargittai
[43] in her paper on the bond lengths of transition metal
halides, and studied by Liu on first transition metal phthal-
ocyanines [36]. And the order also agrees well with the
experiment. The lengths of the Ca–Nm bonds and the
degrees of the <CaNmCa and <CaNcCa also agree with
the order, whereas the lengths of Ca–Nc are contrary to
the order, CoPc < NiPc > CuPc > ZnPc.
Table 1
˚
Bond length (A) and bond angle (°) of experiment and calculation for CuPc, NiPc, ZnPc and CoPc
Parameter
CuPc
Expa
NiPc
Expb
ZnPc
Expc
CoPc
Expd
HF
HF
HF
HF
M–Nc
Ca–Nm
Ca–Nc
Ca–Cb
Cb–Cb
Cb–Nc
Nc–Nd
Nd–Nd
M–Nc–Ca
Nc–Ca–Nm
Ca–Nc–Ca
Nc–Ca–Cb
Ca–Cb–Cb
Cb–Cb–Nc
Cb–Nc–Nd
Nc–Nd–Nd
Ca–Nm–Ca
a
1.935
1.328
1.366
1.453
1.4
1.388
1.377
1.413
126.4
127.6
107.3
110.4
106
1.9321
1.3226
1.3599
1.4405
1.3819
1.3786
1.3674
1.4087
126.37
128.44
106.49
110.17
105.96
120.84
117.63
121.41
121.77
1.83
1.375
1.385
1.46
1.38
1.39
–
1.8441
1.3693
1.3990
1.4256
1.3721
1.3871
1.3840
1.3890
131.96
128.11
107.49
114.52
104.85
121.03
117.40
122.33
116.83
1.98
1.9799
1.3229
1.3521
1.4571
1.3933
1.3872
1.3843
1.3851
124.83
127.11
108.44
108.69
106.28
121.29
117.49
120.82
122.95
1.907
1.317
1.375
1.45
1.384
1.384
1.38
1.385
126.6
127.6
106.7
110.1
106.5
121.4
117.1
121.5
121.5
1.8979
1.3226
1.3813
1.4501
1.3834
1.3796
1.3806
1.3823
126.84
127.83
106.44
110.49
106.81
121.47
117.20
121.51
122.01
1.331
1.369
1.455
1.4
1.393
1.391
1.396
125.4
127.8
109.1
108.8
106.6
121.3
117.3
121.5
123.5
–
130.5
126
99
115.5
105
120
–
121.1
117.9
121
–
117
121.19
Cited from Ref. [38].
Cited from Ref. [39].
Cited from Ref. [40].
Cited from Ref. [41].
b
c
d

K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
5653
Table 2
Energy levels (in eV) of some occupied and unoccupied molecular orbital for CuPc, NiPc, ZnPc and CoPc
CuPc
NiPc
ZnPc
CoPc
ELUMO+3
ELUMO+2
ELUMO+1
ELUMO
ꢀ1.5383
ꢀ1.7062
ꢀ3.1709
ꢀ3.1709
1.9444
ꢀ5.1153
ꢀ7.0957
ꢀ7.4317
ꢀ7.5691
ꢀ7.5926
ꢀ7.6514
B1U
EG
EG
ꢀ1.7659
ꢀ2.2792
ꢀ3.3359
ꢀ3.3359
2.1056
ꢀ5.4415
ꢀ7.4117
ꢀ7.6163
ꢀ7.6807
ꢀ7.6955
ꢀ7.8644
B1U
EG
EG
ꢀ1.2833
ꢀ1.5261
ꢀ3.3577
ꢀ3.3577
1.9692
ꢀ5.3269
ꢀ7.3257
ꢀ7.5804
ꢀ7.6596
ꢀ7.6975
ꢀ7.8514
B1U
EG
EG
ꢀ1.8561
ꢀ1.9211
ꢀ3.6030
ꢀ3.6030
2.1122
ꢀ5.7152
ꢀ7.6599
ꢀ7.9027
ꢀ8.0249
ꢀ8.0762
ꢀ8.1630
B1U
EG
EG
A1G
A1G
A1G
A1G
DE
EHOMO
A1U
EG
EG
B2G
B2U
A2U
A1U
EG
EG
B2G
B2U
A2U
A1U
EG
EG
B2G
B2U
A2U
A1U
EG
EG
B2G
B2U
A2U
EHOMOꢀ1
EHOMOꢀ2
EHOMOꢀ3
EHOMOꢀ4
EHOMOꢀ5
Fig 3a. The molecular orbital map for the HOMO of (a) CuPc, (b) NiPc, (c) ZnPc and (d) CoPc.
Fig 3b. The molecular orbital map for the LUMO of (a) CuPc, (b) NiPc, (c) ZnPc and (d) CoPc.
ca. 686 (experimentally) for Cu(II), 685 for Zn(II), 681 for
Ni(II) and 670 nm for Co(II) correspond to HOMO !
LUMO + 1 transitions, while the Soret bands at ca.
307–345 nm correspond to HOMO + 2 ! LUMO + 1,
ca. 284–298 nm fit to HOMO + 5 ! LUMO + 1, and ca.
225–256 nm correspond to HOMO ! LUMO + 6 transi-
tions, respectively, [37].
carried out to comparatively describe the molecular struc-
tures, molecular orbital and UV–Vis spectra of metallopht-
halocyanine complexes and so the geometries of metal
cations, Cu2+, Ni2+, Zn2+ and Co2+, with six ring clusters
of metallophthalocyanine structure were calculated at the
HF/6-31G(d) level of theory. All of metal cations localized
in the fourfold nitrogen coordination within chosen bulky-
type structures. The average distances between the metal
cations and four coordinated nitrogen atoms in MPcs, esti-
mated by the HF/6-31G(d) calculations, were in the range
5. Conclusions
˚
The cyclotetramerization reaction of the phthalonitrile
derivative in a multi-step reaction sequence resulted in
the formation of novel tetrasubstituted, metal-free phthalo-
cyanine and metallophtalocyanines bearing four thiophen
and triazole heterocyclic peripheral groups. The new com-
pounds were characterized by a combination of IR, 1H
NMR, 13C NMR, UV–Vis, elemental analysis and MS
spectral data. Furthermore, theoretical calculations were
of 1.84–1.97 A, which are close to experimental results. The
natures of the main transitions in electronic absorption
spectra of the four compounds were also assigned.
Acknowledgements
This study was supported by the Research Fund of
Karadeniz
Technical
University,
Project
No.:

5654
K. Serbest et al. / Journal of Organometallic Chemistry 692 (2007) 5646–5654
¨
[19] K. Sancak, M. Er, Y. Unver, M. Yıldırım, I. Degirmencioglu, K.
2006.111.002.4 (Trabzon – Turkey). We are thankful to Dr.
Zekeriya Bıyıklıog˘lu for recording UV–Vis spectra.
Serbest, Transition Met. Chem. 32 (2007) 16–22.
[20] Z. Bıyıklıog˘lu, H. Kantekin, M. Ozil, J. Organomet. Chem. 692
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(2007) 2436–2440.
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