Synthesis, characterization, spectral and electrical properties of peripherally tetratriazole-substituted phthalocyanines and its metal complexes

Article abstract of DOI:10.1016/j.jorganchem.2012.04.010

The substituted [1,2,4]triazole 3 was obtained from the reaction between compound 1 and compound 2. Novel substituted phthalonitrile 5 was prepared by the substitution of the nitro group of 4-nitrophthalonitrile 4 with triazole moiety 3. The synthesis of metal-free, zinc, nickel, cobalt and copper phthalocyanines with four substituted [1,2,4]triazole groups on peripheral position were performed from cyclotetramerization of novel substituted dinitrile compound 5. Metal-free phthalocyanine 6 and its Zn-, Ni-, Co- and Cu- complexes 7-10 were prepared in DMAE at reflux temperature. All new compounds were characterized by a combination of elemental analyses, IR, ¹H/ ¹³C NMR, MS and UV-vis spectroscopy. Aggregation behaviors of NiPc 8 and CuPc 10 were also investigated. While NiPc 8 was aggregated in acetone, DMF, DMSO, THF, ethylacetate and toluene and non-aggregated in dichloromethane and pyridine at 10 × 10^-6 mol dm^-3 concentration, CuPc 10 showed monomeric behavior in dichloromethane, DMSO, DMF, pyridine, THF and showed aggregation in acetone, ethylacetate and toluene at 14 × 10 ^-6 mol dm^-3 concentration. On the other hand, substituted NiPc 8 and CuPc 10 did not show aggregation behavior between 4 × 10 ^-6-14 × 10^-6 mol dm^-3 concentration range in chloroform. Dc and ac conductivity and Impedance Spectroscopy (IS) studies were also done on thin films of compounds 6, 7, 8, 9 and 10 as a function of temperature (295-523 K) and frequency (40-10⁵ Hz) under vacuum (～2 × 10^-3 mbar) in dark. The compounds 7, 8, 9 and 10 showed nearly same dc conductivity values in the measured temperature range. Variation of dc conductivity of 6, 7, 8, 9 and 10 with temperature exhibited the semiconducting behavior. Variation of ac conductivity of the films with frequency represented by the function σ_ac = Aω^s. The results indicated that charge transport mechanism of the films can be explained by hopping and small polaron tunneling model for 6, 7, 8, 9 and 10 depending on temperature and frequency region. Results of the impedance spectra measurements showed that, at high temperatures, depressed semicircles with different radius indicate deviation from Debye dispersion relation.

Full text of DOI:10.1016/j.jorganchem.2012.04.010

Journal of Organometallic Chemistry 712 (2012) 57e66
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterization, spectral and electrical properties of peripherally
tetratriazole-substituted phthalocyanines and its metal complexes
a
b
a
a
ꢀ
ꢀ c
Rıza Bayrak , Kaan Karaoglu , Yasemin Ünver , Kemal Sancak , Fatih Dumludag ,
a,
_
*
ꢀ
ꢀ
Ismail Degirmencioglu
a Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, Kanuni Kampusu, 61080 Trabzon, Turkey
b Department of Chemistry, Faculty of Arts and Sciences, Rize University, 53050 Rize, Turkey
c
_
Department of Physics, Faculty of Arts and Science, Marmara University, 34722 Istanbul, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
The substituted [1,2,4]triazole 3 was obtained from the reaction between compound 1 and compound
Received 25 January 2012
Received in revised form
5 April 2012
2. Novel substituted phthalonitrile
5 was prepared by the substitution of the nitro group of
4-nitrophthalonitrile 4 with triazole moiety 3. The synthesis of metal-free, zinc, nickel, cobalt and copper
phthalocyanines with four substituted [1,2,4]triazole groups on peripheral position were performed from
cyclotetramerization of novel substituted dinitrile compound 5. Metal-free phthalocyanine 6 and its Zn-,
Ni-, Co- and Cu- complexes 7e10 were prepared in DMAE at reflux temperature. All new compounds
were characterized by a combination of elemental analyses, IR, 1H/13C NMR, MS and UVevis spectros-
copy. Aggregation behaviors of NiPc 8 and CuPc 10 were also investigated. While NiPc 8 was aggregated
in acetone, DMF, DMSO, THF, ethylacetate and toluene and non-aggregated in dichloromethane and
pyridine at 10 ꢀ 10ꢁ6 mol dmꢁ3 concentration, CuPc 10 showed monomeric behavior in dichloro-
methane, DMSO, DMF, pyridine, THF and showed aggregation in acetone, ethylacetate and toluene at
14 ꢀ 10ꢁ6 mol dmꢁ3 concentration. On the other hand, substituted NiPc 8 and CuPc 10 did not show
aggregation behavior between 4 ꢀ 10ꢁ6e14 ꢀ 10ꢁ6 mol dmꢁ3 concentration range in chloroform. Dc and
ac conductivity and Impedance Spectroscopy (IS) studies were also done on thin films of compounds 6, 7,
8, 9 and 10 as a function of temperature (295e523 K) and frequency (40e105 Hz) under vacuum
(w2 ꢀ 10ꢁ3 mbar) in dark. The compounds 7, 8, 9 and 10 showed nearly same dc conductivity values in
the measured temperature range. Variation of dc conductivity of 6, 7, 8, 9 and 10 with temperature
exhibited the semiconducting behavior. Variation of ac conductivity of the films with frequency repre-
Accepted 10 April 2012
Keywords:
Phthalocyanine
Aggregation
Electrical characterization
Impedance spectra
Semiconductor
Conductivity
sented by the function sac ¼ A
u
s. The results indicated that charge transport mechanism of the films can
be explained by hopping and small polaron tunneling model for 6, 7, 8, 9 and 10 depending on
temperature and frequency region. Results of the impedance spectra measurements showed that, at high
temperatures, depressed semicircles with different radius indicate deviation from Debye dispersion
relation.
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
Because of the above mentioned importance of Pcs, preparing
novel Pc molecules are important. Unsubstituted Pc is insoluble in
After accidental synthesis of phthalocyanine (Pc) by Braun and
Tcherniac in 1907, many advances have been made in phthalocya-
nine(Pc)chemistry[1e4]. Pcanditstransitionmetal complexeshave
been used in numerous technological applications such as chemical
sensors [3], electrochromic displaying systems [4], non-linear optics
[5], solar cells [6], photo-voltaic optics, molecular electronics [7],
semiconductors [8], liquid cyrstals [9], optical storage devices [10].
common organic solvents and water because of the intermolecular
interaction of the Pc molecules. This interaction results in aggre-
gation that decreases their solubility and minimizes their applica-
tions. For this reason, one of the important goal of this investigation
is to enhance the solubility. Pc derivatives having high solubility
have been obtained by peripheral substitution with bulky or long
alkyl/alkoxy chains [11e15].
[1,2,4] triazoles, a five membered ring having two carbon and
three nitrogen atoms, have been reported as pharmacologically
active compounds [16] and some used as anti-inflammatory [17],
* Corresponding author. Fax: þ90 462 325 3196.
_
ꢀ
ꢀ
E-mail address: ismail61@ktu.edu.tr (I. Degirmencioglu).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2012.04.010

58
R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
antiviral/anti-HIV and anti-tuberculosis [18], antibacterial agents
[19] in medicine. On the other hand, Pcs having substituents
including bulky groups and donor atoms may increase the solu-
bility them [20,21]. To the best of our knowledge, there are many
Pcs that have triazole moiety on the periphery, however aggrega-
tion and electrical properties investigation have been made for only
a few of them [22e24], so we have preferred triazole moiety as
substituent on Pc ring.
In the present paper, metal-free, Zn-, Ni-, Co- and Cu- phtha-
locyanines having [1,2,4]triazole peripheral substituents were
prepared by conventional methods. In addition aggregation
behavior of Ni- and Cu- phthalocyanines in different solvents and at
different concentrations were studied. Furthermore, electrical
properties of metal-free, Zn-, Ni-, Co- and Cu- phthalocyanines
were also investigated.
125.42, 125.12, 124.97, 124.20, 123.83, 122.02, 117.76 (C^N),
115.27 (C^N), 109.57, 13.04 (CH3).
MS (ESI) (m/z): Calculated: 377.40; Found: 377.52 [M]þ.
2.1.2. Metal-free phthalocyanine (6)
Substituted phthalonitrile 5 (0.1 g, 2,65 ꢀ 10ꢁ4 mol) was
dissolved in 10 ml of dry N,N-dimethylaminoethanol (DMAE).
After increasing the temperature to 90 ꢂC, 1,8-diazabicyclo[5.4.0]
undec-7-ene (DBU) (3.79 ꢀ 10ꢁ5 L, 2.65 ꢀ 10ꢁ5 mol) was added to
the media. Thereafter the temperature was raised to 160 ꢂC and
stirred for 24 h under nitrogen. After cooling, the solution was
dropped to ethyl alcohol (40 ml). The solid product was filtrated
and washed with hot ethanol, hot methanol, n-hexane and diethyl
ether. The yellowish green crude product was purified by passing
through a silica gel column with chloroform and then chlor-
oform:methanol (10:1) elution. Yield: 0.027 g (27%), mp. > 300 ꢂC
(decomposition).
2. Experimental
Anal. Calc. for C92H62N20O4: C, 73.10; H, 4.13; N, 18.53.
Found: C, 73.45; H, 4.03; N, 18.38.
All reactions were carried out under an atmosphere of dry,
oxygen-free nitrogen, using standard Schlenk techniques. All
solvents were dried and purified as described by Perrin and
Armarego [25]. Ethyl (1Z)-N-benzoylethanehydrazonoate 1 [26],
IR (KBr tablet) ymax/cmꢁ1
:
3280 (eNH), 3060
(CH]N), 1507 (C]C), 1234
(CeN), 1010 (CeOeC), 929 (CH).
1H NMR (DMSO-d6) (
: ppm): 7.54e7.21 (m, 48H/AreH), 2.27 (s,
12H, CH3).
13C NMR (DMSO-d6) (
y(AreCH),
2922e2852
y(aliph. CH), 1617
y
y
y
(CeOeC)/(CeN), 1165
d
d
d
d
4-(3-methyl-5-phenyl-4H-1,2,4-triazol-4-yl)phenol
3
[26] and
4-nitrophthalonitrile 4 [27] was prepared according to the literature
and 4-aminophenol 2 was purchased from Merck. 1H- NMR/13C NMR
spectra were recorded on a Varian XL-200 NMR spectrophotometer
d: ppm): 161.44, 155.61, 151.87, 148.24,
144.21 (C]Nmethyl), 142.76 (C]Nphenyl), 138.54, 134.60, 127.68,
126.93, 125.56, 124.03, 123.84, 122.67, 121.15, 121.02, 119.89, 108.42,
12.95 (CH3).
in CDCl3 or DMSO-d6, and chemical shifts were reported (d) relative
to Me4Si as internal standard. IR spectra were recorded on a Per-
kineElmer Spectrum one FTeIR spectrometer in KBr pellets. The
MS spectra were measured with a Micromass Quattro LC/ULTIMA
LCeMS/MS spectrometer equipped with chloroformemethanol as
solvent. All experiments were performed in the positive ion mode.
Elemental analyses were performed on a Costech ECS 4010 instru-
ment; the obtained values agreed with the calculated ones. UVevis
spectra were recorded by means of a Unicam UV2-100 spectro-
photometer, using 1 cm pathlength cuvettes at room temperature.
Melting points were measured on an electrothermal apparatus and
are uncorrected.
UVevis (chloroform): lmax/nm [(4 ꢀ 10ꢁ5 log
3
dm3 molꢁ1 cmꢁ1)]:
700 (4.88), 664 (4.80), 644 (4.37), 602 (4.15), 344 (4.58).
MS (ESI) (m/z): Calculated: 1511.61; Found: 1512.86 [M þ H]þ.
2.1.3. The general procedure for synthesis of metallophthalocyanines
7e10
Substituted phthalonitrile 5 (0.1 g, 2,65 ꢀ 10ꢁ4 mol) and corre-
sponding
dry
metal
salts
(Zn(OAc)2
(0.0122
g,
6.63 ꢀ 10ꢁ5 mol); Ni(OAc)2 (0.0117 g, 6.63 ꢀ 10ꢁ5 mol); CoCl2
(0.0086 g, 6.63 ꢀ 10ꢁ5 mol); CuCl2 (0.0089 g, 6.63 ꢀ 10ꢁ5 mol) were
dissolved in 4 ml of dry DMAE. After increasing the temperatuꢁre5 to
90 ꢂC, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (3.79 ꢀ 10 L,
2.65 ꢀ 10ꢁ5 mol) was added to the media. Thereafter the temper-
ature was raised to 160 ꢂC and stirred for 24 h under nitrogen. After
cooling, the solutions were dropped to ethyl alcohol (40 ml). The
solid products were filtrated and washed with hot ethanol, hot
methanol, n-hexane and diethyl ether. The yellowish green crude
products were purified by passing through a silica gel column with
chloroform:methanol (((10:1) for ZnPc) ((9:1) for NiPc) ((11:1) for
CoPc and CuPc)) elution.
2.1. Synthesis
2.1.1. 4-[4-(3-methyl-5-phenyl-4H-1,2,4-triazol-4-yl)phenoxy]
phthalonitrile (5)
4-nitrophthalonitrile 4 (1 g, 5.78 mmol) and compound 3
(1.45 g, 5.78 mmol) were dissolved in dry DMF, under N2 atmo-
sphere and the temperature was increased up to 60 ꢂC. Thereafter,
finely ground dry K2CO3 (0.797, 5.78 mmol) was added
portion-wise over a period of 2 h and the reaction mixture left to
stir for 5 days at this temperature. The completeness of the reaction
was controlled by thin layer chromatography (TLC) (chlor-
oform:methanol (1:1)). The mixture was added to ice-water and
mixed overnight. The resulting precipitate was filtered and dried in
vacuum over P2O5 and recrystallized from ethanol. The pure tawny
product was obtained by column chromatography with silica gel
using chloroform as eluent. Yield: 1.43 g (65.6%), mp.: 233e234 ꢂC.
Anal. Calc. for C23H15N5O: C, 73.20; H, 4.01; N, 18.56.
2.1.3.1. Zn(II) phthalocyanine (7). Yield: 0.032
mp.: > 300 ꢂC (decomposition).
g
(31%),
Anal. Calc. for C92H60N20O4Zn: C, 70.16; H, 3.84; N, 17.79 . Found:
C, 70.56; H, 3.39; N, 17.62.
IR (KBr tablet) ymax/cmꢁ1: 3060
y
(AreCH), 2917e2854
(CH]N), 1506e1471 (C]C), 1231 (CeOeC)/
(CeN), 1043 (CeOeC), 942 (CH).
1H NMR (DMSO-d6) (
: ppm): 7.76e7.73 (d, 4H/AreH), 7.63e7.58
(d, 22H/AreH), 7.50e7.37 (m, 22H/AreH), 2.34 (s, 12H, CH3).
13C NMR (DMSO-d6) (
: ppm): 160.12, 154.76, 152.78, 148.21,
y(aliph.
CH), 1640e1600
(CeN), 1160
y
y
y
d
d
d
d
Found: C, 73.27; H, 3.95; N, 18.62.
IR (KBr tablet) ymax/cmꢁ1: 3060
y
(AreCH), 2917
(CH]N), 1509 (C]C), 1273e1246
(CeN), 1015 (CeOeC), 979 (CH).
: ppm): 7.81e7.79 (d, 1H/AreH), 7.32e7.16 (m,
11H/AreH), 2.35 (s, 3H, CH3).
13C NMR (CDCl3) (
: ppm): 160.65, 154.56, 149.66, 145.78
(C]Nmethyl), 143.13 (C]Nphenyl), 139.86, 135.42, 129.64, 128.19,
y
(aliph. CH),
d
2231 (C^N), 1638e1590
(CeOeC)/(CeN), 1170
1H NMR (CDCl3) (
y
y
144.76 (C]Nmethyl), 142.43 (C]Nphenyl), 139.96, 135.53, 126.87,
125.46, 124.85, 123.72, 122.36, 121.52, 121.01, 120.46, 118.26, 109.83,
13.32 (CH3).
y
d
d
d
d
UVevis (chloroform): lmax/nm [(4 ꢀ 10ꢁ5 log
3
dm3 molꢁ1 cmꢁ1)]:
d
678 (4.90), 610 (4.14), 354 (4.66).
MS (ESI) (m/z): Calculated: 1575.00; Found: 1575.65 [M]þ.

R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
59
2.1.3.2. Ni(II) phthalocyanine (8). Yield: 0.024
mp.: > 300 ꢂC (decomposition).
g
(23.1%),
between ꢁ1 V and 1 V using a Keithley model 617 programmable
electrometer. Ac conductivity and impedance spectra (IS)
measurements were performed using Keithley model 3330 LCZ
meter in the frequency range of 40e105 Hz at different tempera-
tures (295e523 K). All the electrical measurements were per-
formed under vacuum (w2 ꢀ 10ꢁ3 mbar) in dark. The temperature
of the substrate is monitored by a chromel-alumel thermocouple.
The tip of the thermocouple was in contact with the substrate. The
accuracy of the temperature measurements was better than
ꢃ0.5 ꢂC. Both dc and ac conductivity data were recorded using
an IEEE-488 data acquisition system incorporated to a personal
computer.
Anal. Calc. for C92H60N20O4Ni: C, 70.46; H, 3.86; N, 17.86.
Found: C, 70.37; H, 3.77; N, 17.94.
IR (KBr tablet) ymax/cmꢁ1: 3061
y
(AreCH), 2924e2853
(CH]N), 1507e1466 (C]C), 1234 (CeOeC)/
(CeN), 1081 (CeOeC), 968 (CH).
1H NMR (DMSO-d6)
ppm): 7.87e7.70 (bd, 4H/AreH),
7.51e7.49 (d, 22H/AreH), 7.37 (m, 22H/AreH), 2.28 (s, 12H, CH3).
13C NMR (DMSO-d6) (
: ppm): 160.43, 154.45, 152.72, 147.15,
y(aliph.
CH), 1645e1594
(CeN), 1188
y
y
y
d
d
d
(d:
d
143.56 (C]Nmethyl), 141.54 (C]Nphenyl), 139.62, 135.34, 126.24,
125.13, 124.67, 123.96, 122.37, 121.88, 121.17, 120.73, 119.79, 109.12,
13.59 (CH3).
UVevis (chloroform): lmax/nm [(1 ꢀ10ꢁ5 log
3
dm3 molꢁ1 cmꢁ1)]:
3. Results and discussion
670 (5.27), 604 (4.67), 331 (4.97).
MS (ESI) (m/z): Calculated: 1568.29; Found: 1568.78 [M]þ.
3.1. Outlook of the synthesized compounds
2.1.3.3. Co(II) phthalocyanine (9). Yield: 0.017
mp.: > 300 ꢂC (decomposition).
g
(16.4%),
Fig. 1 shows the schematic representation of the synthetic route
of novel products. The proposed structures of novel compounds
have been identified by 1H/13C NMR, IR, UV-vis, elemental analysis
and MS spectral data.
Anal. Calc. for C92H60N20O4Co: C, 70.45; H, 3.86; N, 17.86.
Found: C, 70.36; H, 3.71; N, 17.98.
IR (KBr tablet) ymax/cmꢁ1: 3060
y
(AreCH), 2922e2852
(CH]N), 1506e1464 (C]C), 1235 (CeOeC)/
(CH).
dm3 molꢁ1 cmꢁ1)]: 662
y(aliph.
CH), 1647e1591
y
y
y
3.2. Spectroscopic characterization via complementary techniques
(CeN), 1185 d(CeN), 1082 d(CeOeC), 969 d
UVevis (DMF): lmax/nm [(4 ꢀ 10ꢁ5 log
3
3.2.1. Synthesis of substituted phthalonitrile 5
(4.85), 602 (4.27), 334 (4.67).
Base catalyzed nucleophilic aromatic nitro substitution reaction
of 4-nitrophthalonitrile have been achieved by many authors
[28,29]. In general, nucleophilic displacement of a nitro group from
an activated aromatic substrate can be effectively achieved by
variety of strong nucleophiles under dipolar aprotic conditions for
example in DMF or DMSO [30,31].
MS (ESI) (m/z): Calculated: 1568.59; Found: 1568.14 [M]þ.
2.1.3.4. Cu(II) phthalocyanine (10). Yield: 0.023
mp.: > 300 ꢂC (decomposition).
Anal. Calc. for C92H60N20O4Cu: C, 70.24; H, 3.84; N, 17.81. Found:
C, 70.45; H, 3.77; N, 17.76.
g
(22.1%),
In this connection, we focused on the preparation of our key
product 5 by nucleophilic displacement of nitrite from an activated
benzene 4 that has already been mostly used for the synthesis of
oxoaryl phthalonitriles [32,33]. Base promoted synthesis of 5 in dry
DMF at 60 ꢂC was carried out with dry K2CO3. In the IR spectrum,
the disappearence of eOH stretching/deformation of 3 at 3349/
1331 cmꢁ1 and NO2 stretching of compound 4 at 1519, 1333 cmꢁ1
and the appearance of C^N absorption band at 2231 cmꢁ1 clearly
proves the formation of compound 5. Addionally, the structure of 5
was supported by 1H NMR spectrum in chloroform-d. After SNAr
reaction, D2O exchangeable phenolic eOH at 10.15 ppm dis-
appeared. Among other things, the integral ratio of aromatic/
aliphatic protons separately helps the characterization of 5. Also in
the MS mass spectrum of 5, the molecular ion peak at m/z ¼ 377.52
[M]þ supports the expected structure for this compound.
IR (KBr tablet) ymax/cmꢁ1: 3060
y
(AreCH), 2923e2853
(CH]N), 1506e1464 (C]C), 1236 (CeOeC)/
(CH).
dm3 molꢁ1 cmꢁ1)]:
y(aliph.
CH), 1646e1590
y
y
y
(CeN), 1185 d(CeN), 1082 d(CeOeC), 969 d
UVevis (Chloroform): lmax/nm [(1 ꢀ10ꢁ5 log
3
677 (5.07), 611 (4.63), 341 (4.84).
MS (ESI) (m/z): Calculated: 1573.14; Found: 1574.43 [M þ H]þ.
2.2. Preparation of thin films of the compounds for electrical
measurements
In order to prepare thin films of compounds, firstly, certain
amounts of compounds were dissolved in pyridine. After homo-
geneous solutions were obtained, the solutions were deposited
onto interdigital transducers (IDT) by smearing method. Eventually,
thin films of compounds were obtained by evaporating pyridine
from homogeneous solutions of the compounds which is deposited
onto IDT. Deposition of the films onto IDT was performed at room
temperature in air.
3.2.2. Syntheses of metal-free 6 and metallophthalocyanines 7e10
Most commonly, substituted phthalocyanines are prepared by
cyclotetramerization of substituted phthalonitrile or 1,3-diimino-
1H-isoindoles [34,35]. While peripherally tetrasubstituted Pcs are
obtained from 4-substituted phthalonitrile, non-peripherally
substituted phthalocyanines are synthesized from 3-substituted
analogs [33,35]. In both cases, four possible isomers can be
designed by their molecular symmetry as C4h, C2v, Cs and D2h. The
peripherally tetrasubstituted compounds always occur in the
2.3. Electrical measurements
To reveal the electrical properties of the compounds such as dc
and ac conductivity values, charge transport mechanism and
semiconducting behavior, two types of measurements were per-
formed. First one is investigation of dc electrical properties of the
compounds, and second was of the a.c. properties. Interdigital
transducer (IDT) was employed as transducer in order to investi-
gate electrical properties of the compounds. Interdigital trans-
ducers were fabricated onto pre-cleaned glass substrate. The
expected statistical mixture of these isomers (12.5% C4h, 25% C2v
,
50.5% Cs and 12.5% D2h). But for the non-peripherally tetrasub-
stituted ones, percentages of these isomers depends on the central
metal ion and the structure of the peripheral substituent [36]. In
this connection, the new phthalocyanines 6e10 were prepared as
a statistical four regioisomers and no effort was made to separate
them.
transducer contains ten finger pairs of gold electrodes with 100
mm
width. Separations between the gold electrodes was also 100 mm.
Dc electrical studies were done on the films of 6, 7, 8, 9 and 10 from
room temperature up to 523 K. Dc measurements were performed
On the other hand, there are many useful reaction conditions for
the synthesis of the phthalocyanine derivatives [37,38]. For various

60
R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
Fig. 1. Synthetic route of novel compounds.
substituted phthalonitriles, a convenient high-yield procedure is
the reaction in the presence of strong non-nucleophilic bases such
as 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) or 1,5-diazabicyclo
[4,3,0]non-5-ene (DBN) either in N,N-dimethylaminoethanol
(DMAE) or different used solvents [39]. Furthermore, these reac-
tions are easy to perform and work comparatively mild conditions.
Therefore, the metal-free phthalocyanine 6 was prepared by using
substituted phthalonitrile 5 and metallophthalocyanines 7e10
were also synthesized by using substituted phthalonitrile 5 and
corresponding dry metal salts in DMAE and in the presence of
a strong organic base such as DBU at reflux temperature (Fig. 1).
These phthalocyanines were purified by successive column
chromatography.
typical shielding of inner core protons could not be observed due to
the probable strong aggregation [41].
3.3. UVevis absorption spectra
All phthalocyanines were very soluble in most of organic
solvents such as chloroform, THF, dichloromethane, DMF, DMSO,
pyridine whereas CoPc 9 was soluble only in pyridine, DMF and
DMSO. So UVevis spectra of all phthalocyanines were measured in
chloroform but only that of CoPc was measured in DMF. For
metalated phthalocyanines 7, 8 and 10 in chloroform, the Q bands
caused by
p / p* transitions were observed at 678, 670 and
677 nm respectively (Fig. 2 and Fig. 3a and b). For compound 9, in
DMF, the Q band was observed at 662 nm (Fig. 4). The shoulders of
these metallophthalocyanines were observed at: 610 for 7, 604 for
8, 602 for 9 and 611 for 10. For Q band regions of metal-
lophthalocyanines, the longer wavelength absorptions are due to
the monomeric species and shorter wavelenth absorptions
(shoulders) are due to the aggregated species [42]. So, at measured
concentrations, monomeric behavior of metallophthalocyanines
were proved by the dominance of the longer wavelength absorp-
All new phthalocyanines were characterized by IR, 1H and 13C
NMR, mass spectrometry elemental analysis and UV/Vis. All the
results were in accordance with the predicted structures as shown
in Section 2. The IR spectra of all these phthalocyanines feature
peaks at around 1600 cmꢁ1 (CH]N) and 1500 cmꢁ1 (C]C) as
expected. Also the sharp peak at 2231 cmꢁ1 for the C^N vibrations
of substituted phthalonitrile
5 disappeared after conversion,
indicative of phthalocyanine formation. The IR spectra of phthalo-
cyanines are very similar except the peak at 3280 cmꢁ1 that belongs
to NH group of metal-free phthalocyanine 6.
tions. The B-bands arising from deeper
p levels / LUMO were
observed at: 354, 331, 334 and 341 nm for 7, 8, 9 and 10 respectively
(Figs. 2e4). Differently from metallophthalocyanines, the Q band
absorptions of metal-free phthalocyanines split to Qx and Qy and
there are two strong absorption bands in visible region. In chloro-
form, the splitting Q band of compound 6 was observed at 700 and
664 nm with shoulders at 644 and 602 nm, evidence of non-
degenerate D2h symmetry. Additionally, B-band of compound 6
was observed at 344 nm (Fig. 5).
The 1H-NMR spectra of 9 and 10 could not be determined
because of the presence of paramagnetic cobalt and copper atoms
[40]. The 1H-NMR spectra of phthalocyanines 6e8 were also very
similar. The resonances belonging to aromatic protons were
observed in the range 7.54e7.21 ppm for 6, 7.76e7.58 ppm for 7 and
7.87e7.49 ppm for 8, integrating for a total of 48 protons. The
aliphatic methyl protons of these phthalocyanines 6e8 were
observed in the range 2.34e2.27 ppm as singlet integrating for
a total of 12 protons. Additionally, for metal free phthalocyanine 6,
Aggregation, usually defined as a coplanar association of rings
from monomer to dimer or higher order complexes, is dependent

R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
61
Fig. 4. UVevis spectra of compound 9 in DMF at 1 ꢀ 10ꢁ5 mol dmꢁ3
.
Fig. 2. UVevis spectra of compound 7 in CHCl3 at 4 ꢀ 10ꢁ5 mol dmꢁ3
.
through the films were recorded versus applied voltages from ꢁ1 V
to 1 V. Dc conductivity values of the films were determined using
Eq. (1) and the slope of the IeV curves.
on the concentration, nature of the solvent, nature and connection
of the substituents, coordinated metal ions and temperature [43].
The aggregation behavior of the phthalocyanine complexes 8 and
10 were investigated in different solvents and at different
concentrations. The UVevis spectra of compounds 8 and 10 in
chloroform at different concentrations are shown in Fig. 3a and b.
Both compounds 8 and 10 showed monomeric behavior between
4 ꢀ 10ꢁ6e14 ꢀ 10ꢁ6 mol dmꢁ3 concentrations (Fig. 3a and b).
The absorpsion spectra of NiPc 8 and CuPc 10 in different
solvents are shown in Fig. 6a and b. As can be seen in Fig. 6a, the
substituted NiPc 8 was aggregated in acetone, DMF, DMSO, THF,
ethylacetate and toluene and non-aggregated in dichloromethane
and pyridine at 10 ꢀ 10ꢁ6 mol dmꢁ3 concentration. Additionally,
CuPc 10 showed monomeric behavior in dichloromethane, DMSO,
DMF, pyridine, THF and aggregated in acetone, ethylacetate and
toluene at 14 ꢀ 10ꢁ6 mol dmꢁ3 concentration (Fig. 6b). Hyper-
chromic effect of Pcs are generally described as the increase of lmax
ꢀ ꢁꢀ
ꢁ
I
V
d
sdc
¼
(1)
ð2n ꢁ 1Þlh
where, (I/V) is slope of the IeV graph, d is distance between the
finger pair, n is number of the finger pair, l is overlap length and h is
thickness of the electrodes. More information on IDT used in this
study can be found in the literature [45].
Fig. 7 shows temperature dependence of dc conductivity of the
films of 6, 7, 8, 9 and 10 in the temperature range of 295e523 K. In
order to provide numerical comparison, dc conductivity values of
the films of 6, 7, 8, 9 and 10 at 295 K and at 523 K were given in
Table 1. As seen from Fig. 7, conductivity of the film 6 increases with
increasing temperature in the measurement range of temperature
and conductivity of the films 7, 8, 9, and 10 increases with
increasing temperature up to 478 K (295K ꢄ T < 478 K, region I).
Further, conductivity of the film 6 is less than that of the other films
measured and also conductivity of the film 8 is greater than that of
the films 6, 7, 9 and 10 at all temperatures in this region. Since dc
conductivity of the films increases with increasing temperature
in the temperature range of 295e478 K, we can say that the
compounds of 6, 7, 8, 9 and 10 are in semiconductor nature. The
measured conductivity values are nearly in agreement with
the previous reports for different phthalocyaynines [46]. However,
the effect of the tetra [1,2,4]triazole substituents on electrical
properties of the films of compounds is clearly seen by examining
the dc conductivity values of our metal free and zinc and cobalt
substituted compounds with that of the imidazole substituted
phthalocyanines reported by Yabas¸ et al. [45]. By comparing the dc
and
3
values (or absorbance) of Q band and B-band. Pyridine, as
solvent, evidently display hyperchromic effect on the phthalocya-
nine complexes 8 and 10 (Fig. 6a and b) [44]. In addition, for
aggregated species of compounds 8 and 10, the shoulders due to
aggregation are red shifted by w15 nm as compared to their
monomeric species (Fig. 6a and b).
3.4. DC electrical properties
Dc measurements in dark ambient provide information on
conduction processes in the compounds. In this study, dc conduc-
tivity measurements were performed on the films of 6, 7, 8, 9 and
10 at different temperatures during heating from 295 K to 523 K
under vacuum (w2 ꢀ 10ꢁ3 mbar) in dark. Current values passing
Fig. 3. (a) Absorption spectra of the compound 8 in chloroform at different concentrations. (b) Absorption spectra of the compound 10 in chloroform at different concentrations.

62
R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
Fig. 7. Variation of dc conductivity with temperature for the film of 6, 7, 8, 9 and 10.
Fig. 5. UVevis spectra of compound 6 in CHCl3 at 4 ꢀ 10ꢁ5 mol dmꢁ3
.
presented in Table 1. Activation energies of the compounds take
places between the values of 0.48e0.88 eV. The calculated activa-
tion energy values of the films 6, 7, 8, 9 and 10 are consistent with
other reports in different phthalocyanine films [50]. It is also
observed that activation energy of our metal free film (0.48 eV)
(6) is less than that of imidazole substituted metal-free phthalo-
cyanines (0.83e0.86 eV). We may say that tetra [1,2,4]triazole
substituents decrease activation energy of the compounds
with respect to imidazole substituted ones (0.82 eV for (6) and
(0.75e0.86) eV for zinc substitute phthalocyanine) [45].
conductivity values we may say that tetra [1,2,4]triazole substitu-
ents increase nearly 50e100% times the conductivity of the
compounds depending on measurement temperature. Another
comparison was also done for dc conductivity of 8 and that of the
NiPc reported by El-Nahass and co-workers [47]. By examining the
dc conductivity values of the samples it was not observed mainly
difference between the films of the compounds nearly at room
temperature. But, at high temperatures dc conductivity of 8 was
found greater than that of the compound reported. As a result,
we may say that tetra [1,2,4]triazole substituents increase the dc
conductivity of the compounds, especially at high temperatures.
Second region (478K ꢄ T ꢄ 523 K) can be characterized by the
decrease in conductivity with temperature (for the films 7, 8, 9
and 10) and shows negative activation energy. The behavior of
conductivity with temperature may arise from different crystallo-
graphic phases or the occurrence of a phase transition [48]. The
linear dependence of dc electrical conductivity on the reciprocal
absolute temperature (1/T) in the first temperature region can be
defined using the relation [49].
3.5. A.C. properties
Ac measurements give information that can be used to deter-
mine charge transfer mechanism within the film such as hopping
model or band theory under particular operating conditions. A.c.
conductivity and impedance measurements were performed as
a function of frequency in the frequency range of 40e105 Hz
at different temperatures (295 Ke523 K) in vacuum ambient
(w2 ꢀ 10ꢁ3 mbar) in dark. Fig. 8a shows variation of ac conductivity
with frequency for the film 8 at indicated temperatures. Behavior of
ac conductivity of the film 8 can be examined as a function of
temperature and frequency. From this point of view we can say that
ac conductivity of the film 8 increases with increasing temperature
and frequency in the all measurement temperature and frequency
range of measurement. Temperature dependence of a.c. conduc-
tivity of the film can be analyzed in two parts, i) low temperature
region (T ꢄ w438 K) and ii) high temperature region (T > w438 K).
ꢀ
ꢁ
ꢁEA
sdc
¼
s0exp
(2)
kT
where, sdc is the dc conductivity, so represents the value of sdc at
(1/T) ¼ 0, T is the absolute temperature, k is the Boltzman’s constant
and EA is the activation energy.
The activation energy values of the film 6, 7, 8, 9 and 10 were
calculated from the slope of the Ln sdc - 1/T graph. The values were
Fig. 6. (a) Absorption spectra of the compound 8 in different solvents. Concentration ¼ 10 ꢀ 10ꢁ6 mol dmꢁ3. (b) Absorption spectra of the compound 10 in different solvents.
Concentration ¼ 14 ꢀ 10ꢁ6 mol dmꢁ3
.

R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
63
Table 1
Dc conductivity values (at 295 K and 523 K) and activation energies (region I) of the
films 6, 7, 8, 9 and 10.
Films
s295 K (S/cm)
s523 K (S/cm)
EA (eV)
6
7
8
9
1.25 ꢀ 10ꢁ10
1.50 ꢀ 10ꢁ10
3.28 ꢀ 10ꢁ10
1.41 ꢀ 10ꢁ10
1.48 ꢀ 10ꢁ10
6.95 ꢀ 10ꢁ7
1.08 ꢀ 10ꢁ5
8.14 ꢀ 10ꢁ6
1.19 ꢀ 10ꢁ5
1.11 ꢀ 10ꢁ5
0.48
0.82
0.81
0.88
0.86
10
At the temperatures T ꢄ w438 K, conductivity of the film strongly
depends on frequency. It can be seen from the Fig. 8a, conductivity
of the film increases with increasing frequency in this temperature
region. At the temperatures T > w438 K, frequency dependence of
a.c. conductivity of the film decreases. The sac vs
u curves of 7, 9 and
Fig. 9. Variation of ac conductivity with frequency at 295 K, 438 K and 523 K for the
film 6, 7, 8, 9 and 10.
10 were similar to those in Fig. 8a. Fig. 8b shows variation of ac
conductivity with frequency for the film 6 at indicated tempera-
tures. As seen from the Fig. 8b, film 6 shows similar behavior with
film of 8 up to 438 K. At the temperatures T ꢅ 438 K, slope of the
temperatures T > 438 K. The behavior of s with temperature for the
films 6 (in middle and high frequency region), 7, 8 and 10 were
similar to film of 9.
curves increases with temperature at the frequencies
u
ꢄ 1 kHz. In
order to compare the behavior of the ac conductivity all of the films,
variation of ac conductivity with frequency for the film 6, 7, 8, 9 and
10 at 295 K, 438 K and 523 K were presented in Fig. 9. By examining
the results of ac measurements, in general, we may say that sac
(6) < sac (7) < sac (10) < sac (9) < sac (8) at all measurement
frequency range and temperature. This order of the ac conductivity
data of the films for the temperatures 295 K and 523 K at indicated
frequencies can be seen easily from Table 2.
For ac charge transport mechanism, the hopping model predicts
a frequency dependent ac conductivity, which increases with
increasing frequency under the condition that, the frequency
exponent s ꢄ 1 [44]. The Hopping model, which was developed by
Elliot [53], assumes that charge carriers hop between sites over the
potential barrier separating them. The model gives ac conductivity
which can be expressed to a first order approximation given by (for
single electron hopping),
Frequency dependence of the measured ac conductivity of all of
the films follows a universal power law given by Eq. (3) [51,52].
p
3N2 3 3 0u
24
sac
ð
u
; TÞ ¼
Ru6
(4)
sac ¼ Aus
(3)
where
3
is the dielectric constant of the material,
3
o
that of free
where
u is the angular frequency, A and s are material depended
space, N is the spatial density of defect states and Ru is the hopping
distance. This model predicts a temperature-dependent s value
which is given by,
constants. Variation of exponent s of frequency was also examined
to investigate the ac charge transport mechanism. Exponent s
values were calculated from slope of straight portions of the sac vs
u
curves. Temperature dependence of s values can be analyzed in
three different frequency regions. The three different frequency
6kBT
Wm
s ¼ 1 ꢁ
b
¼ 1 ꢁ
(5)
regions can be defined as low frequency region (
u
< 103 Hz),
middle frequency region (103 Hz ꢄ
u
ꢄ 104 Hz) and high frequency
where kB is Boltzmann’s constant and Wm is the binding energy. In
this model s values decreases with increasing temperature. By
examining the slope of straight portions of the sac vs
observed that variation of derived s values of the films shows
a general tendency to decrease with increasing temperature all
over the measured frequency range and temperature (except that
of 6 in low frequency region at the temperatures T > 438 K).
In the band model, the ac conductivity should be frequency
independent and drops at sufficiently high frequency. In the
region (104 Hz <
u
ꢄ 105 Hz), respectively. In these frequency
regions, s values decrease with increasing temperature for all of the
films (except for 6 in low frequency region (for T > 438 K)).
Temperature dependence of the s values for the film 9 for three
different frequency regions was given in Fig. 10. Variation of s
values with temperature in low frequency region for 6 was also
given in this figure. As seen from Fig. 10, in low frequency region,
u curves, it is
s
values for 6 increase with increasing temperature at the
Fig. 8. (a) Variation of ac conductivity with frequency at indicated temperatures for the film 8 (b) Variation of ac conductivity with frequency at indicated temperatures for the
film 6.

64
R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
Table 2
Ac conductivity values of the films 6, 7, 8, 9 and 10 at the temperatures 295 K and
523 K.
Films s295 K (S/cm)
s523 K (S/cm)
40 (Hz) 104 (Hz)
105 (Hz)
40 (Hz)
104 (Hz)
105 (Hz)
6
7
8
9
*
*
*
*
*
2.00 ꢀ 10ꢁ8 2.50 ꢀ 10ꢁ7 4.00 ꢀ 10ꢁ8 5.10 ꢀ 10ꢁ6 7.50 ꢀ 10ꢁ6
2.00 ꢀ 10ꢁ8 2.25 ꢀ 10ꢁ7 5.99 ꢀ 10ꢁ6 7.09 ꢀ 10ꢁ6 9.40 ꢀ 10ꢁ6
4.00 ꢀ 10ꢁ8 2.55 ꢀ 10ꢁ7 1.41 ꢀ 10ꢁ5 1.85 ꢀ 10ꢁ5 2.30 ꢀ 10ꢁ5
3.00 ꢀ 10ꢁ8 2.05 ꢀ 10ꢁ7 1.10 ꢀ 10ꢁ5 1.21 ꢀ 10ꢁ5 1.61 ꢀ 10ꢁ5
2.50 ꢀ 10ꢁ8 2.00 ꢀ 10ꢁ7 9.77 ꢀ 10ꢁ6 1.05 ꢀ 10ꢁ5 1.43 ꢀ 10ꢁ5
10
* no data were obtained due to lowest measurement limit of the device.
quantum mechanical tunneling (QMT) model [54], the exponent s
is almost equal to 0.8 and increases slightly with temperature or
independent of temperature. Because of this, QMT model is not
applicable to our results. In this model, s is given by s ¼ 1þ(4/lnuso),
Fig. 11. The Nyquist plot at temperatures 295K ꢄ T ꢄ 523 K for the film of 9 (inset for
T ꢅ 458 K).
where,
u is the angular frequency and so the relaxation time of the
carriers. In the overlapping-large polaron tunneling (QLPT) model
[55], the exponent s is both frequency and temperature dependent.
This model is also not applicable to our results. In the small polaron
quantum mechanical tunneling (SP) model, the exponent s is an
increasing function of temperature [53]. It is also well known that
the low values of s indicate multihopping process, while high
values of s indicate single hopping process. By comparing the
models with our results, charge transport mechanism of the film 6,
7, 8, 9 and 10 can be interpreted in two parts depending on both
temperature and frequency.
Zð
u
Þ ¼ Z0ð
u
Þ þ jZ00ð
u
Þ
(6)
where Z0(
u u) are the real and imaginary parts of imped-
) and Z00(
ance. Z0(
u
) - Z0(
u) curves (Nyquist plot) at indicated temperatures
for the film 9 were presented in Fig. 11. Quasi-vertical lines were
observed in the impedance spectra of the film 9 up to 438 K. This
type of curves can be modeled a resistor parallel with a capacitor in
series with another resistor [56]. Temperature effect on impedance
spectra can be easily seen from inset in Fig. 11. By examining the
curves drawn in this inset, depressed semicircles with difference
radius were observed at indicated temperatures. Additionally, it is
also observed that, the radius of the semicircle decreases with
increasing temperature. An ideal semicircle in complex plane only
appears in Debye dispersion relations for single-relaxation time
process. Most of the materials show a pronounced deviation from
Debye treatment as in our case. In this case, the relaxation time is
considered as a distribution of values, rather than a single-relaxa-
tion time [57]. The depressed semicircles with different radius
indicate deviation from Debye dispersion relation. Therefore, the
equivalent circuit is modified to include a constant phase element
(CPE). The existence of the CPE represents a slight distribution of
relaxation times instead of a discrete relaxation time. The series
resistance in the equivalent circuit represents the ohmic losses in
the test fixture and electrode sheet resistance. The parallel resis-
tance is of the coating material in parallel with that of the substrate.
The intercepts of the semicircular arcs with real axis give us an
estimate of the bulk resistance of the material. Since intersection
points of the semicircular arcs with real axis approaches to origin
At low temperature region (T ꢄ w438 K) dominant conduction
mechanism can be modeled by single hopping all over the measured
frequency range. At high temperature region (T > w438 K)
conduction mechanism can be modeled depending on frequency
region, i) low frequency region (
region (1 kHz 10 kHz) iii) high frequency region
(10 kHz <
u < 1 kHz) and ii) middle frequency
ꢄ
u
ꢄ
u
ꢄ 100 kHz). In low frequency region, dominant
conduction mechanism can be modeled by multihopping for 7, 8, 9
and 10 by small polaron quantum mechanical tunneling (SP) for 6. In
middle and high frequency regiondominant conduction mechanism
can be modeled by single hopping for all of the films.
Impedance measurements depending on frequency at different
temperatures were employed in order to obtain more information
about the electrical properties of the films, such as capacitive
behavior, bulk resistance, e.t.c. The measured impedance data were
plotted in complex plane (coleecole plot) for all of the films. The
complex impedance Z(
frequency as,
u), can be represented as a function of
Fig. 10. Temperature dependence of s for three different frequency regions for the film
Fig. 12. The Nyquist plot at temperatures 478 K for the film of 6, 7, 8, 9 and 10 (inset for
T ¼ 523 K, x-axis and y-axis was not drawn in the same scale to show behavior of the
curves).
9 and 6 (for low frequency region) (low frequency region:
u < 1 kHz, middle frequency
region: 1 kHz ꢄ
u
ꢄ 10 kHz, high frequency region: 104 Hz <
u
ꢄ 105 Hz).

R. Bayrak et al. / Journal of Organometallic Chemistry 712 (2012) 57e66
65
depending on frequency region, i) low frequency region (
and ii) middle frequency region (1 kHz ꢄ
frequency region (10 kHz <
ꢄ 100 kHz). In low frequency region,
u
< 1 kHz)
u
ꢄ 10 kHz) iii) high
u
dominant conduction mechanism can be modeled by multihopping
for 7, 8, 9 and 10 by small polaron quantum mechanical tunneling
(SP) for 6. In middle and high frequency region dominant
conduction mechanism can be modeled by single hopping for all of
the films. From impedance spectra results of the films, it’s observed
that bulk resistance of the films decreases with increasing
temperature that indicates semiconducting behavior. Impedance
spectra results in consisted with dc electrical results.
Acknowledgment
Fig. 13. Frequency dependence of impedance curves (Bode plot) for the film 7 at
indicated temperatures in the temperature range of 295e523 K (inset for the film 10).
The Authors thank to The Research Fund of Karadeniz Technical
University, Project No: 2010.111.002.3 (Trabzon/Turkey).
with increasing temperature, we can conclude that bulk resistance
of the films decreases with increasing temperature indicating
semiconductor property. The result is in consisted with dc electrical
results. In order to compare bulk resistance and behavior of the
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u u) curves at 478 K and at 523 K
(inset) were presented in Fig. 12. As can be seen from the Fig. 12,
bulk resistance (Rb) of the films can be ordered as Rb (8) < Rb
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ꢄ 105) at the temperatures 458, 478, 498 and 523 K. The
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8 and CuPc 10 were researched in different solvents and different
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