Design of novel binuclear phthalocyanines formed by dioxyphenyl bridges: Synthesis and investigation of thermal and antioxidant properties

Article abstract of DOI:10.1002/zaac.201200220

4, 4′-(1, 4-Phenylenebis(oxy)diphthalonitrile was synthesized by reaction of hydroquinone with 4-nitrophthalonitrile. Binuclear metallophthalocyanines 2-4 were obtained by the reaction between 4, 4′-(1, 4-phenylenebis(oxy)diphthalonitrile and 4-(benzo [d]

Full text of DOI:10.1002/zaac.201200220

Job/Unit: Z12220
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ARTICLE
DOI: 10.1002/zaac.201200220
Design of Novel Binuclear Phthalocyanines formed by Dioxyphenyl Bridges:
Synthesis and Investigation of Thermal and Antioxidant Properties
[a]
M. Salih Ag˘ırtas,*[a] Ilkay Gümüs, Veysi Okumus,[b] and Abdurrahman Dundar[b]
˙
¸
¸
Keywords: Phthalocyanines; Antioxidants; Thermal properties; Synthesis; Binuclear complexes
Abstract. 4,4Ј-(1,4-Phenylenebis(oxy)diphthalonitrile was synthesized phthalocyanines 2-4 were investigated by TG and DTA. In addition,
by reaction of hydroquinone with 4-nitrophthalonitrile. Binuclear
metallophthalocyanines 2–4 were obtained by the reaction between
4,4Ј-(1,4-phenylenebis(oxy)diphthalonitrile and 4-(benzo [d] [1,3] di-
oxol-5-ylmethoxy)phthalonitrile in the presence of metal salts. These
antioxidant properties of compounds II, 3 and 4 were investigated.
Their radical-scavenging capacity and chelating effects was fully
studied. The maximum 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH)
were obtained from compound 3. Chelating effects on ferrous ions
new compounds were characterized by using elemental analysis, FTIR, were 91.6 % at concentration of 100 mgL–1 with compound II.
1H-NMR and UV/Vis spectroscopic data. Thermal properties of
clear metal in the same molecule may provide additional fea-
1 Introduction
tures such as increased solubility and reactivity. Herein, we
Phthalocyanines have been considered as synthetic por-
reported the synthesis, thermal stability and antioxidant prop-
phyrin analogs. They possess a conjugated system of π-elec-
erties of binuclear phthalocyanines carrying six benzo [d] [1,3]
trons and exhibit the ability to chelate metal ions in the center
dioxol-5-ylmethoxy groups.
of the ring. Many of properties of phthalocyanines are highly
dependent on the extent of intermolecular π-π stacking interac-
2 Experimental Section
tions between the planar faces of the macrocycles. Phthalocy-
anines and related derivatives have been widespread applica-
tions in various areas including chemical sensors,[1] non-linear
optic devices,[2,3] optical recording media,[4] semi-conduc-
tors,[5] dyes and pigments,[6] catalysts,[7] electrochromic de-
vices,[8] photo chromic materials,[9] photosensitizers for photo-
dynamic therapy,[10–12] liquid crystals,[13] and promising H2
adsorbents.[14,15]
Recently, attention has been attracted to phthalocyanines
containing two metal atoms, due to their interesting properties.
Binuclear and multi nuclear phthalocyanine derivatives have
been reported in the literature.[16–20] It is well known that anti-
oxidants reduce the risk for chronic diseases such as cancer
and heart disease. Researches focused on the elucidation of the
antioxidant and therapeutic properties of new phthalocyanine
compounds have been continuously performed by research
groups This is the reason that the search for selective methods
of synthesizing binuclear phthalocyanines with various struc-
tures currently attracts special attention. The presence of binu-
2.1 General
4-(benzo [d] [1,3] dioxol-5-ylmethoxy)phthalonitrile (II) was prepared
according to the literature procedure.[21] All chemicals used were rea-
gent grade. The solvents were purified according to standard procedure
and stored over molecular sieves (4 Å).[22] All reactions were carried
out under dry nitrogen atmosphere unless otherwise noted. Melting
points were measured on an electrothermal apparatus. Electronic spec-
tra were recorded with a Hitachi U-2900 Spectrophotometer. Routine
IR spectra were recorded with a Thermo Scientific FTIR (ATR sam-
pling accessory) spectrophotometer. Elemental analyses results were
found in good agreement with calculated values. 1H NMR spectra were
recorded with a Bruker 300 MHz spectrometer in DMSO; chemical
shifts were reported (δ) relative to Me4Si as an internal standard. Ther-
mal experimental was performed with a SETARAM TG/DTA/DSC-16
instrument.
2.2 Synthesis of Compound 1
A mixture of hydroquinone (0.55 g, 5 mmol) and 4-nitrophthalonitrile
(1.73 g, 10 mmol) in dimethylformamide (DMF) (20 mL) was stirred
under nitrogen. K2CO3 (5 g, 36 mmol) was added into the mixture
over a period of 2 h. The reaction mixture was stirred under nitrogen
at room temperature for 24 h. Afterwards, the reaction mixture was
poured into water (200 mL) and stirred. The precipitate was filtered
and washed with water. Yield: 1.5 g (83 %). The compound is soluble
in DMF, dimethyl sulfoxide, hot ethyl acetate and butanol. Mp:
260 °C. 1H NMR (300 MHz, [D6]DMSO): δ = 8.15 (2H, d, Ar-H),
7.80 (2H, d, Ar-H), 7.54 (2H, dd, Ar-H), 7.40 (4H, s, Ar-H) ppm. IR:
* Prof. Dr. M. S. Ag˘ırtas¸
Fax: +90-432-225-11-88
E-Mail: salihagirtas@hotmail.com
[a] Department of Chemistry
Faculty of Science
Yüzüncü Yıl University
65080 Van, Turkey
[b] Department of Biology
Faculty of Arts and Science
Siirt University
56100, Siirt, Turkey
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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M. S. Ag˘ırtas¸, I. Gümüs¸, V. Okumus, A. Dundar
ARTICLE
υ = 3076, 2232, 1595, 1500, 1481, 1284, 1 243, 1191 cm–1. Anal ylformamide (DMF) were purchased from Sigma (Sigma-Aldrich
calculated for C22H10N4O2: C, 72.92; H, 2.78; N, 15.46 %, found C, GmbH, Sternheim, Germany).
72.83; H, 2.81; N, 15.35 %.
2.7 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) Radical-
Scavenging Activity
2.3 Synthesis of Compound 2
Compound 1 (0.091 g, 0.25 mmol), 4-(benzo [d] [1,3] dioxol-5-yl-
methoxy)phthalonitrile (0.209 g, 0.75 mmol), ZnCl2 (0.020 g) and dry
In this experiment, the scavenging ability of the free and metal
bounded compounds on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical
DMF (1.5 mL) were placed in a standard tube in the presence of DBU
was performed according to an earlier reported method[23] with some
(0.05 mL) under nitrogen and held at 160 °C for 20 h. After cooling
modifications. Different concentrations (5-100 mg/L) of the com-
to room temperature, the reaction mixture was precipitated by adding
pounds (0.5 mL) were mixed with a DMF solution (2 mL) of DPPH
water. The product was washed with water, EtOH, acetone, and CHCl3.
radicals. The mixture was shaken vigorously and then left to stand in
DMF was added to the residue in order to dissolve the product. The
the dark for 30 min. The inhibition of the DPPH radical was deter-
reaction mixture was precipitated by water in the presence of NaHCO3.
mined by spectrophotometer at 517 nm. The DPPH radical scavenging
The precipitate was filtered and washed with EtOH, butanol, and
activity (%) was calculated by the following equation:
CHCl3. The purity was analyzed by thin-layer chromatography. This
compound is soluble in THF, DMF, and DMSO. Yield: 0.139 g (25 %).
Radical scavenging activity (%) = (1 – Asample/Acontrol) ϫ100,
Calcd. for C118H70N16O20Zn2: C, 65.53; H, 3.26; N, 10.36 %, found C,
65.66; H, 3.33; N, 10.41 %. 1H NMR (300 MHz, [D6]DMSO): δ =
Where Asample is the absorbance in the presence of sample and Acontrol
8.05–6.95 broad (Ar-H), and aliphatic protons at 6.04 (OCH2O) and
is the absorbance in the absence of sample, respectively. BHA and
5.15 (CH2O) ppm. IR: υ = 3066, 2884, 1604, 1485, 1442, 1216,
BHT were used as standards.[23]
1035 cm–1. UV/Vis (DMF): λmax (log ε): 684 (5.23), 618 (4.71), 352
(5.13) nm.
2.8 Chelating Effects on Ferrous Ions
2.4 Synthesis of Compound 3
Chelating effects of DMF solution of compounds was determined ac-
cording to an earlier reported method.[24] Briefly, an amount (0.5 mL)
Compound 1 (0.091 g, 0.25 mmol), 4-(benzo [d] [1,3] dioxol-5-yl-
of a DMF solution of the compounds with varied concentrations
(5–100 mgL–1) was incubated with a FeCl2 solution (25 μL, 2 mm).
Afterwards, the reaction was initiated by addition of ferrozine (100
μL, 5 mm) and was left standing for 10 min at room temperature.
Metal chelating activity was determined by spectrophotometer at 562
nm. The percentage inhibition of the ferrozine–Fe2+ complex forma-
tion was calculated as follows:
methoxy)phthalonitrile (0.209 g, 0.75 mmol), Co(CH3COO)2
(0.020 g) and dry DMF (1.5 mL) were placed in a standard tube in the
presence of DBU (0.05 mL) under nitrogen and held at 160 °C for
20 h. After cooling to room temperature, the reaction mixture was
precipitated by adding water. The product was washed with water,
EtOH, acetone, and CHCl3. The purity was analyzed by thin-layer
chromatography. Compound 3 is soluble in THF, DMF, and DMSO.
Yield: 0.125 g (23 %). Calcd. for C118H70N16O20Co2: C, 65.93; H,
3.28; N, 10.42 %, found C, 65.81; H, 3.35; N, 10. 38 %. IR: υ = 3063,
2956, 1607, 1499, 1488 1441, 1405, 1362, 1242, 1222, 1190, 1096,
1036, 928, 811, 753 cm–1. UV/Vis (DMF): λmax (log ε): 670 (5.04),
340 (5.09) nm.
Chelating ability (%) = (Ablank - Asample)/Ablank ϫ100;
Where Ablank is the absorbance of the control reaction (containing only
FeCl2 and ferrozine), and Asample is the absorbance of the compounds/
reference. EDTA was used as a positive control.[24]
2.5 Synthesis of Compound 4
3 Results and Discussion
Compound 1 (0.091 g, 0.25 mmol), 4-(benzo [d] [1,3] dioxol-5-yl-
methoxy)phthalonitrile (0.209 g, 0.75 mmol), Cu(CH3COO)2
(0.020 g) and dry DMF (1.5 mL) were placed in a standard tube in the
presence of DBU (0.05 mL) under nitrogen and held at 160 °C for
20 h. After cooling to room temperature, the reaction mixture was
precipitated by adding water. The product was washed with water,
EtOH, acetone, and CHCl3. The purity was analyzed by thin-layer
chromatography. The compound is soluble in THF, DMF, and DMSO.
Yield: 0.119 g (21 %). Calcd. for C118H70N16O20Cu2: C, 65.64; H,
3.27; N, 10.38 %, found C, 65.73; H, 3.24; N, 10.43 %. IR: υ = 3069,
2954, 1606, 1486, 1441, 1230, 1190, 1156, 1036, 929, 810, 746 cm–1.
UV/Vis (DMF): λmax (log ε): 683 (5.07), 618 (4.39), 350 (4.92) nm.
3.1 Synthesis and Characterization
4,4Ј-(1,4-Phenylenebis(oxy)diphthalonitrile 1 was obtained
by the reaction between hydroquinone and 4-nitrophthalo-
nitrile in dry DMF in the presence of dry K2CO3 and at room
temperature. Binuclear metallophthalocyanines 2–4 were ob-
tained from 4,4Ј-(1,4-Phenylenebis(oxy)diphthalonitrile 1 and
4-(benzo [d] [1,3] dioxol-5-ylmethoxy)phthalonitrile (1:3) and
corresponding anhydrous metal salts ZnCl2, Co (CH3COO)2,
Cu (CH3COO)2 in the presence of N2 atmosphere. The route
for synthesis of compounds 1–4 was shown in Scheme 1.
Characterization of the compounds contain a combination of
2.6 Biological Assay
1
methods, including elemental analysis, IR, H NMR and UV/
Vis spectra confirmed the proposed structures of the com-
pounds. The thermal properties of phthalocyanines 2–4 were
1,1-Diphenyl-2-picryl-hydrazyl (DPPH), ferrous chloride, 3-(2-pyrid-
yl)-5,6-bis(4-phenyl-sulfonic acid)-1,2,4-triazine (Ferrozine), butylated
hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and Dimeth- investigated by thermo gravimetric analysis.
2
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Design of Novel Binuclear Phthalocyanines formed by Dioxyphenyl Bridges
1
Figure 1. The H NMR spectrum of compound 1.
Scheme 1. Synthesis of compounds 1–4.
In the IR spectrum of 1 the disappearance of NO2 and OH
stretching, along with the appearance of new bands at 2232,
1595 and 1243 cm–1 arising from CϵN, C=C and Ar–O–Ar
groups, respectively. They are in agreement with the proposed
structure. After conversion of the 4-(benzo [d] [1,3] dioxol–5-
ylmethoxy)phthalonitrile and tetranitrile compound 1 into
phthalocyanine 2 the band of the characteristic vibration of
CϵN at 2232 cm–1 disappeared. For phthalocyanines 3 and 4
similar bands were observed (Ar at 3066 cm–1, CH2 at
2884 cm–1, Ar–O–Ar bands at 1216 cm–1, C=C (in phenyl
rings) bands at 1604 cm–1 and disappeared CϵN bands at
2232).
Figure 2. UV/Vis spectra of 2–4 in DMF.
1
In the H NMR spectrum of compound 1 in [D6]DMSO the
signal of the aromatic protons appears at 8.15–7.40 (Ar–H)
(Figure 1). In the 1H NMR spectrum of compound 2 in
[D6]DMSO, the aromatic proton signals appear at 8.05–6.95
ppm (Ar–H) and aliphatic proton peaks at 6.04 (OCH2O) and
1
5.15 (CH2O). A common feature of the H NMR spectrum of
the compound 2 are the broad absorptions probably caused by
aggregation of the phthalocyanine, which is frequently encoun-
tered at the concentrations used for NMR spectroscopic mea-
surements. All the analytical and spectral data are consistent
with the predicted structures. Elemental analyses corresponded
closely with the values calculated for 1–4.
The UV/Vis spectra of the phthalocyanines 2–4 in
DMF showed characteristic Q band absorptions between 684–
670 nm, which were attributed to the π-π* transition from the
highest occupied molecular orbital (HOMO) to the lowest un-
occupied molecular orbital (LUMO) of the Pc ring. The other
bands (B) in UV region at 340–352 nm were observed due to
transition from the deeper π levels to the LUMO.The absorp-
Figure 3. TG/DTA curves of compound 2.
tion spectra of 2–4 in DMF is shown in Figure 2. Indeed Bayo After initial loss of moisture at 100–130 °C, the loss of weight
et al have reported that in the binuclear species the π system at major decomposition temperature was 36 % for 2, 53 % for
is not delocalized on the whole of both phthalocyanine cycles, 3 and 54 % for 4 (Figure 3, Figure 4, Figure 5). The residues
which explain the nil movement of the Q band toward red.[25] remaining after thermal decomposition correspond to the metal
Thermogravimetric (TG) analyses of the phthalocyanine oxides. The observed thermal stability of metallo phthalocyan-
complexes were carried out in air and nitrogen atmosphere. ines in air was in the order of 2Ͼ3Ͼ4. This study revealed
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that these new phthalocyanines 2–4 can serve good thermal
stability.
Figure 6. Radical-scavenging activity on DPPH radicals (%) of the
compounds.
3.3 Chelating Effects on Ferrous Ions
To examine the effect of the chelating activity of the com-
pounds against Fe2+, the chelating experiments were carried
out at different concentrations (5, 25, 50, 75 and 100 mgL–1).
Results are shown in Figure 7. The chelating activity of II
increased from 55.8 to 91.6 % with increasing concentration
from 5 to 100 mgL–1. whereas the chelating activities of the 3
and 4 decreased when the concentrations increased. The results
revealed that the maximum chelating activities of II, 3 and 4
were 91.6, 78.5 and 75.8 %, at concentrations of 100, 5 and
25 mgL–1 respectively. EDTA showed the maximum chelating
activity at all concentrations. As a result, at a concentration of
II of 100 mgL–1 may be used instead of EDTA for chelating
activity.
Figure 4. TG/DTA curves of compound 3.
Figure 5. TG/DTA curves of compound 4.
Figure 7. Chelating effect of compounds on ferrous ion.
3.2 DPPH Radical-Scavenging Activity
The model of scavenging the stable DPPH· radical is a
method to interpret antioxidant activities in short time to com-
pare with the other methods. The impact of antioxidants on
4 Conclusion
A series of binuclear phthalocyanines carrying six benzo [d]
DPPH radical scavenging was showed as a result of their hy- [1,3] dioxol-5-ylmethoxy groups was synthesized. The com-
1
drogen donating ability.[26] Figure 6 shows the effects of the pounds were characterized by elemental analyses, FTIR, H-
scavenging ability of the free and metal bounded compounds NMR and UV/Vis spectroscopy. The new metallo phthalocyan-
on DPPH radical. From those compounds a maximum DPPH ines were studied by thermogravimetry and differential thermal
radical-scavenging activity was obtained from 3. The DPPH analysis. All of the three metallophthalocyanines have higher
radical-scavenging activity of 3 was 76.7 % and 77.7 % at thermal stability, compared to the phthalocyanines substituted
concentrations of 25 and 50 mgL–1, respectively. Compounds with different organic groups. With regard to the scavenging
II and 4 did not show significant DPPH radical-scavenging effect on hydroxy free radicals, compound 3 has the highest at
activity. BHA and BHT showed higher DPPH scavenging ac- concentration of 100 mgL–1. On the other hand, compound II
tivity than all studied compounds and the maximum DPPH has shown a higher chelating activity on ferrous ions than com-
radical scavenging activities were found to be 93.4 % and 92.8 pounds 3 and 4. As a result, compounds 3 and ll show DPPH-
at a concentration of 100 mgmL–1, respectively.
scavenging activity and chelating activity.
4
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Design of Novel Binuclear Phthalocyanines formed by Dioxyphenyl Bridges
[11] Y. Zeng, X. L. Wang, Y. J. Yang, J. F. Chen, J. W. Fu, X. Tao,
Acknowledgments
Polymers 2011, 52, 1766.
[12] A. M. V. M. Pereira, A. R. M. Soares, M. J. F. Calvete, D. L.
Te Gema, J. Porphyrins Phthalocyanines. 2009, 13, 419.
[13] C. Deibel, D. Janssen, P. Heremans, V. D. Cupere, Y. Geerts,
M. L. Benkhedir, G. J. Adriaenssens, Org. Electr. 2006, 7, 495.
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[15] C. H. Lee, R. Filler, J. Y. Lee, J. Li, B. K. Mandal, Renew. Energy
2010, 35, 1592.
This study was supported by the Research Fund of Yüzüncü Yıl Uni-
versity (2010-FBE-YL151).
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Received: May 14, 2012
Published Online: ᭿
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M. S. Ag˘ırtas¸,* I. Gümüs¸, V. Okumus, A. Dundar ........... 1–6
Design of Novel Binuclear Phthalocyanines formed by Di-
oxyphenyl Bridges: Synthesis and Investigation of Thermal
and Antioxidant Properties
6
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