Polyhedron 28 (2009) 2268–2276

Contents lists available at ScienceDirect

Polyhedron

journal homepage: www.elsevier .com/locate /poly

Synthesis, characterization, aggregation and thermal properties of a novelpolymeric metal-free phthalocyanine and its metal complexes

Ahmet Bilgin a,*, Çigdem Yagcı a, Ufuk Yıldız b, Ersel Özkazanç c, Erdogan Tarcan c

a Department of Science Education, University of Kocaeli, 41380 Kocaeli, Turkeyb Department of Chemistry, University of Kocaeli, 41380 Kocaeli, Turkeyc Department of Physics, University of Kocaeli, 41380 Kocaeli, Turkey

a r t i c l e i n f o

Article history:Received 13 January 2009Accepted 10 April 2009Available online 3 May 2009

Keywords:AggregationBisphthalonitrileElectrical conductivityPolymeric phthalocyanine

0277-5387/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.poly.2009.04.026

* Corresponding author. Tel.: +90 262 3032438; faxE-mail address: abilgin@kocaeli.edu.tr (A. Bilgin).

a b s t r a c t

A novel polymeric metal-free phthalocyanine (M = 2H) and its metal complexes (M = Zn, Cu, Co and Ni)were prepared by the tetramerization reaction of 3,6,9-Tris(p-tolylsulfonyl)-1,11-bis(3,4-dicyanophen-oxy)-3,6,9-triazaundecane 5 with the appropriate materials. The electrical conductivities of the metal-free phthalocyanine and the metal complexes, measured in air, were found to be �10�6–10�5 S m�1.The aggregation property of the zinc complex 7 was investigated with Ni2+, Cu2+, Co2+, Pb2+, Cd2+ andAg+ cations. Thermal analysis of the polymers were done by differential scanning calorimetry (DSC)and thermal gravimetric analysis (TGA) at a heating rate of 10 �C min�1 under a nitrogen atmosphere.All the novel compounds were characterized by using elemental analysis, UV–Vis, FT–IR, NMR and MSspectral data and DSC, DTA/TG techniques.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Phthalocyanines (Pcs) consisting of a planar macrocycle with an18 p-electron system have been extensively studied due to theirunique optical, electronic, catalytic and structural properties [1].There has been growing interest in the use of phthalocyanines ina variety of new technological fields such as semiconductor devices[2], electrochromic display devices [3], liquid crystals [4], Lang-muir–Blodgett films [5], catalysts [6], gas sensors [7–9] and asphotosensitizers in photodynamic therapy of cancer [10].

Polymeric phthalocyananines are also very interesting sincethey belong to a class of p-conjugated semiconductor polymers,which offer a unique combination of properties. Being discoveredin the 1950s, polymeric phthalocyanine remains an enigmaticmaterial and many of its intrinsic properties are known ratherinsufficiently [11–13]. Polymeric phthalocyanines were mainlyprepared via polycyclotetramerization reactions of bifunctionalmonomers such as aromatic tetracarbonitriles, various oxy-, ary-lenedioxy- and alkylenedioxy-bridged diphthalonitriles, and othernitriles or tetracarboxylic acid derivatives in the presence of metalsalts or metals [11,12,14–16]. The electrical properties of poly-meric phthalocyanines are of interest because of their conjugatedstructure and stability against light, heat, moisture and air. Hencepolymeric phthalocyanines are suitable candidates for use as envi-ronmentally stable electrically conductive materials [14–16]. Theirstructural similarity to chlorophyll has also made them useful for

ll rights reserved.

: +90 262 3032403.

applications in artificial solar cells [17]. The ion-binding ability ofphthalocyanines containing homo- and hetero-donor atoms inperipheral substituent groups is receiving considerable attentionin view of their effect on the aggregation of the molecules. Afterpolymerization reactions, polymeric phthalocyanines will havemany donor atoms and thus high metal binding ability.

Recently, several types of monomeric and polymeric phthalocy-anines with various functional groups have been synthesized byour group. These phthalocycanines have peripheral substituentswith several macrocyclic or podand units [15,16,18–22].

In the present work, we describe the synthesis and character-ization of a novel polymeric metal-free phthalocyanine and metalcomplexes containing peripherally long triazadioxa derivativeswhich may allow the new functionalized materials to be of impor-tance in the preparation of analytical chemicals such as new kindsof heavy metal extraction agents. We have examined the electricalconductivities of the polymers in air atmosphere. The aggregationproperties of the polymer 7 and the thermal properties of all thepolymers were investigated.

2. Experimental

2.1. Materials

Phosphorus pentoxide (P2O5), p-toluenesulfonyl chloride, dieth-ylenetriamine, ethylene carbonate, potassium hydroxide, metha-nol, activated carbon, celite, 1,8-diazabicyclo[5.4.0]-undec-7-ene(DBU), ethanol, 1-pentanol, dimethylformamide (DMF), tetrahy-drofuran (THF), chloroform, dichloromethane, petroleum ether,

A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276 2269

quinoline, sulfuric acid, hydrochloric acid, pyridine, acetone, so-dium thiosulfate, acetonitrile, sodium carbonate, dioxane, n-hex-ane, lithium, glacial acetic acid, silica gel, ammonia, MgSO4,CoCl2�6H2O, NiCl2�6H2O, Cu(Ac)2�H2O and Zn(Ac)2�2H2O were re-ceived from Merck and used as supplied. Potassium carbonatewas received from Merck and used after drying in oven at 250 �Cfor 36 h. All organic solvents were dried and purified by the usualmethods. 4-Nitrophthalonitrile was synthesized as described in theliterature [23]. N,N0,N0 0-Tris(p-tolylsulfonyl)diethylene-triaminewas synthesized according to the literature [24].

2.2. Measurements

Melting points of the compounds were determined with anelectrothermal melting point apparatus and were uncorrected. 1HNMR spectra were measured on a Bruker AMX 400 MHz NMR spec-trometer in DMSO-d6 with Me4Si as an internal reference. 13C NMRspectra were recorded on a Bruker AMX 100 MHz NMR spectrom-eter with DMSO-d6 as the solvent and with Me4Si as an internal ref-erence. Transmission IR spectra of the samples were obtained on aFT–IR spectrophotometer (Shimadzu FT–IR-8201 PC) with the sam-ples in KBr pellets. Optical spectra in the UV–Vis region were re-corded with a model Shimadzu 1601 UV–Vis spectrometer using10 mm pathlength cuvettes at room temperature. For the electricalmeasurements, the surfaces of the samples were covered with sil-ver paste to form electrodes. The dielectric permittivity and ACconductivity of the samples were performed between 100 Hz and1 MHz frequency range at room temperature by using a LCR meter(Agilent 4284A). Mass spectra were measured on a Micromass LCTMass spectrometer. Elemental analyses were performed on aCHNS-932 LECO elemental analyzer. The metal contents of themetallophthalocyanine polymers were determined with a Unicam929 AA spectrophotometer. Differential thermal analysis was per-formed on a TGA Q600 TA instrument under nitrogen (100 mL/min) atmosphere with a heating rate of 10 �C/min in the tempera-ture range 30–700 �C. Differential scanning calorimetry (DSC) wasperformed on a Perkin Elmer Jade DSC under nitrogen atmospherewith a heating rate of 10 �C/min over the temperature range 50–700 �C.

2.3. Preparation of 3,6,9-Tris(p-tolylsulfonyl)-3,6,9-triazaundecane-1,11-diol (3)

A three-necked, round bottomed flask equipped with a mechan-ical stirrer and reflux condenser was charged with compound 1(4.35 g, 7.5 mmol), ethylene carbonate (2) (1.5 g, 17.05 mmol)and finely powdered potassium hydroxide (0.016 g, 0.29 mmol).The stirred mixture was heated at 165 �C for 5 h under an inertnitrogen atmosphere. The reaction mixture was then allowed tocool to 90 �C, and 10 mL of ethanol was added through the con-denser as rapidly as possible. 0.15 g of activated carbon was addedto the solution and refluxed for 30 min. The temperature was thenincreased to 120 �C and the suspension was stirred for 30 minlonger, and filtered through Celite. Water (10 mL) was added drop-wise to the stirred solution, but no precipitate was observed. Thereaction mixture was extracted with chloroform (5 � 35 mL). Afterdrying on MgSO4, the solvent was evaporated. The product 3 was aviscous brown liquid. After dissolving in toluene, the solution waskept in a refrigerator and the precipated colorless solid productthat subsequently formed was filtered. The final product 3 wasdried over P2O5 in vacuo at 50 �C.

Yield: 4.41 g (89%). M.p.: 104–105 �C. Rf: 0.43 (Chloro-form:petroleum ether 7:3). Anal. Calc. C29H39N3O8S3 (653.82): C,53.27; H, 6.01; N, 6.43; S, 14.71. Found: C, 53.49; H, 6.27; N,6.17; S, 14.94%. FT–IR (KBr, cm�1): 3390 (O–H), 3068–3030 (Aro-matic @CH), 2944–2882 (–CH2–), 1599 (C@C), 1494, 1456, 1332

(SO2), 1261, 1160 (SO2), 1089–1001 (CH2O–), 909, 812, 717, 645,552. 1H NMR (DMSO-d6), d (ppm): 7.74–7.67 (d, 6H, ArH), 7.45–7.36 (d, 6H, ArH), 4.87 (br. s, 2H, OH), 3.60–3.18 (m, 16H, NCH2,OCH2) 2.42 (s, 3H, ArCH3), 2.40 (s, 6H, ArCH3). 13C NMR (DMSO-d6), d (ppm): 143.9, 143.6, 135.7, 135.4, 129.8, 127.4, 126.9 (ArC), 59.9 (CH2OH), 49.8, 49.3, 49.1 (CH2N), 21.5 (CH3), 21.3 (CH3).MS (ES+), m/z: 676.2 [M+Na]+.

2.4. Preparation of 3,6,9-Tris(p-tolylsulfonyl)-1,11-bis(3,4-dicyanophenoxy)-3,6,9-triazaundecane (5)

3,6,9-Tris(p-tolylsulfonyl)-3,6,9-triazaundecane-1,11-diol (3)(4.41 g, 6.75 mmol) and 4-nitrophthalonitrile (4) (2.36 g,13.50 mmol) were dissolved in 10 mL of dry DMF in a 100 mLthree-necked flask and the mixture was stirred at room tempera-ture under an inert atmosphere and degassed three times. Thentemperature was increased to 50 �C. Finely powdered K2CO3

(2.83 g, 20.25 mmol) was added to the solution in eight equal po-tions at 30 min intervals. The reaction mixture was stirred at50 �C for 6 days. The reaction was monitored by a thin layer chro-matography (CHCl3:MeOH, 7:3). At the end of this period, the mix-ture was cooled and poured into ice (100 g), and mixed for 4 morehours. The precipitate that formed was filtered and washed withwater and EtOH. After recrystallization from MeOH, the obtainedproduct 5 was dried over P2O5 in a vacuum oven at 50 �C to yielda light yellow powder.

Yield: 5.38 g (88%). M.p.: 138–139 �C. Anal. Calc. C45H43N7O8S3

(906.06): C, 59.65; H, 4.78; N, 10.82; S, 10.62. Found: C, 59.42; H,5.02; N, 10.60; S, 10.97%. FT–IR (KBr, cm�1): 3086–3043 (Aromatic@CH), 2980–2880 (aliphatic CH2), 2232 (C„N), 1599 (aromatic –C@C–), 1564, 1493, 1458, 1339–1308 (SO2), 1256 (Ar–OCH2),1157 (SO2), 1089, 979, 814, 719, 699, 646, 549. 1H NMR (DMSO-d6), d (ppm): 8.21 (d, 2H, ArH), 8.01 (d, 2H, ArH), 7.96 (s, 2H,ArH), 7.69–7.54 (m, 6H, ArH), 7.38–7.26 (m, 6H, ArH), 4.21 (br. s,4H, ArOCH2), 3.53 (br. s, 4H, NCH2CH2OAr), 3.33–3.18 (m, 8H,NCH2CH2NCH2CH2N), 2.38 (s, 3H, ArCH3), 2.35 (s, 6H, ArCH3). 13CNMR (DMSO-d6), d (ppm): 161.9, 145.1, 143.2, 135.3, 134.9,131.2, 130.4, 128.7, 127.5, 119.8, 118.6, 117.2, 115.4 (CN), 114.9(CN), 107.8, 69.6 (CH2OAr), 52.6, 49.7, 49.3, 21.4, 20.9. MS (ES+),m/z: 907.2 [M+H]+, 751.1 [M-Ts]+.

2.5. Preparation of polymeric metal-free phthalocyanine (6)

A mixture of 5 (0.906 g, 1.0 mmol), n-pentanol (5.0 mL) and 1,8-diazabicyclo[5,4,0] undec-7-ene (DBU) (0.15 mL, 0.16 g, 1.0 mmol)was placed in a standard Schlenk tube under nitrogen atmosphereand degassed two times. Then temperature was increased to160 �C. The reaction mixture was stirred at 160 �C for 18 h. Afterthe reaction mixture was cooled to room temperature, ethyl alco-hol (10 mL) was added dropwise and mixed for half an hour. Thedark green precipitate was filtered and washed with MeOH anddiethyl ether. The dark green product 6 was dried at 50 �C undervacuum over P2O5.

Yield: 0.78 g (86%). M.p.: >300 �C. Anal. Calc. (C180H174-N28O32S12)n (3626.25) (for (for nitrile end groups): C, 59.62; H,4.84; N, 10.82; S, 10.61. Found: C, 53.49; H, 6.27; N, 6.17; S,14.94%. FT–IR (KBr, cm�1): 3294 (N–H), 3063 (Aromatic @CH),2928–2866 (aliphatic CH2), 2225 (C„N), 1629 (C@N), 1604 (aro-matic –C@C–), 1549, 1460, 1337 (SO2), 1227 (Ar–OCH2), 1153(SO2), 1087, 1035 (N–H), 810, 708, 648, 538.

2.6. Preparation of polymeric zinc and copper complexes (7, 8)

A mixture of compound 5 (0.906 g, 1.0 mmol), zinc acetatedihydrate (0.114 g, 0.5 mmol) or cupric acetate monohydrate(0.100 g, 0.50 mmol) and amyl alcohol (5 mL) was put in a standard

2270 A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276

Schlenk tube and the temperature was increased to 90 �C. DBU(0.15 mL, 1.0 mmol) was added dropwise to the suspension atthe same temperature. Then the temperature was increased to160 �C and the reaction was stirred at 160 �C for 18 h under a nitro-gen atmosphere. After the reaction mixture was cooled to roomtemperature, ethanol (10 mL) was added and mixed for 30 min.The crude products were collected by filtration and washed withmethanol, DMF, water and acetone. The final green 7 and darkgreen 8 products were dried under vacuum over P2O5 at 50 �C.

2.6.1. Compound 7Yield: 0.98 g (96.1%). M.p.: >300 �C. Anal. Calc. (C180H176N24-

O40S12Zn)n (3765.61): C, 57.41; H, 4.71; N, 8.93; S, 10.22; Zn,1.74. Found: C, 57.72; H, 4.46; N, 8.65; S, 10.47; Zn, 1.95%. FT–IR(KBr, cm�1): 3402 (imide N–H), 3057 (Aromatic @CH), 2928–2864 (CH2), 1770 (sym. C@O), 1718 (asym. C@O), 1645 (–C@N–),1601 (Aromatic –C@C–), 1487, 1456, 1395, 1334 (SO2), 1222 (Ar-OCH2), 1155 (SO2), 1085–1043, 940, 810, 715, 650, 543.

2.6.2. Compound 8Yield: 0.92 g (91.5%). M.p.: >300 �C. Anal. Calc. (C180H176-

N24O40S12Cu)n (3763.78): C, 57.44; H, 4.71; N, 8.93; S, 10.22; Cu,1.69. Found: C, 57.72; H, 4.53, N, 9.27; S, 10.49; Cu, 1.46%. FT–IR(KBr, cm�1): 3386 (imide N–H), 3064 (Aromatic @CH), 2951–2824 (CH2), 1772 (sym. C@O), 1714 (asym. C@O), 1645 (–C@N–),1607 (Aromatic –C@C–), 1510, 1454, 1400, 1340 (SO2), 1229 (Ar-OCH2), 1157 (SO2), 1089–1018, 954, 814, 718, 646, 548.

2.7. Preparation of polymeric cobalt and nickel complexes (9, 10)

A mixture of compound 5 (0.906 g, 1 mmol), dry quinoline(3 mL) and CoCl2�6H2O (0.120 g, 0.5 mmol) or NiCl2�6H2O(0.122 g, 0.5 mmol) was charged in a standard Schlenk tube anddegassed several times with nitrogen. The reaction mixture wastreated at 210–220 �C for 18 h under a nitrogen inert atmosphere.After 18 h of refluxing, the reaction mixture was cooled to roomtemperature and then 10 mL of ethanol was added to the mixtureslowly and stirred for 30 min. The obtained green 9 and dark green10 products were filtered off. The crude products were washedwith water, MeOH and diethyl ether. The final products (9 and10) were dried under vacuum over P2O5 at 50 �C.

2.7.1. Compound 9Yield: 1.0 g (97.4%). M.p.: >300 �C. Anal. Calc. (C180H176N24O40-

S12Co)n (3759.17): C, 57.51; H, 4.72; N, 8.94; S, 10.23; Co, 1.57.Found: C, 57.29; H, 4.93; N, 8.65; S, 10.42; Co, 1.74%. FT–IR (KBr,cm�1): 3368 (imide N–H), 3048 (Aromatic @CH), 2953–2729(CH2), 1770 (sym. C@O), 1719 (asym. C@O), 1640 (–C@N–), 1598(Aromatic –C@C–), 1474, 1325 (SO2), 1224 (ArOCH2), 1126 (SO2),1084–1024, 984, 785, 735, 546.

2.7.2. Compound 10Yield: 1.01 g (98.2%). M.p.: >300 �C. Anal. Calc. (C180H176N24-

O40S12Ni)n (3758.92): C, 57.52; H, 4.72; N, 8.94; S, 10.23; Ni, 1.56.Found: C, 57.81; H, 4.97; N, 9.19; S, 9.87; Ni, 1.83%. FT–IR (KBr,cm�1): 3437 (imide N–H), 3053 (Aromatic @CH), 2926–2731(CH2), 1768 (sym. C@O), 1721 (asym. C@O), 1654 (–C@N–), 1604(Aromatic –C@C–), 1533, 1489, 1460, 1341 (SO2), 1234 (ArOCH2),1155 (SO2), 1089–1020, 991, 810, 723, 651, 546.

2.8. The conversion of cyano end groups of the polymeric metal-freephthalocyanine into imido groups (6a)

A sample of compound 6 (150 mg) was dissolved in a minimumvolume of H2SO4 (96 wt.-%) at room temperature. After 3–4 h ofstirring, the reaction mixture was filtered. The filtered part was

poured into excess amount of ice-water mixture. The dark greencrude product was washed with distilled water until the residuewashing water was neutral. Then the final product 6a was washedwith ethanol, diethyl ether and dried under vacuum over P2O5 at50 �C.

Yield: 118 mg (78.7%). M.p.: >300 �C. Anal. Calc. (C180H178N24

O40S12)n (3702.25) (for imide end groups): C, 58.40; H, 4.85; N,9.08; S, 10.39. Found: C, 58.17; H, 4.59; N, 9.43; S, 10.68%. FT–IR(KBr, cm�1): 3380 (imide N–H), 3275 (N–H), 3056 (Aromatic@CH), 2938–2740 (CH2), 1774 (sym. C@O), 1720 (asym. C@O),1627 (–C@N–), 1600 (Aromatic –C@C–), 1565, 1458, 1345 (SO2),1230 (ArOCH2), 1163 (SO2), 1086, 1035 (N–H), 964, 815, 730,648, 540.

2.9. Metal analysis of the polymeric metal complexes

A sample of the polymeric metal complexes (7–10) (10 mg) wasadded into concentrated sulfuric acid (2.5 mL) and concentratednitric acid (3.5 mL). The mixture was heated for 2 h at 160 �C inan oil-bath. The solution was firstly digested in conc. HCl acid solu-tion and then diluted with deionize water (500 mL). The determi-nation of metal ions was conducted by atomic absorptionmeasurements.

3. Results and discussion

The synthesis of the 3,6,9-Tris(p-tolylsulfonyl)-3,6,9-triazaun-decane-1,11-diol (3) was performed by starting with N,N0,N0 0-Tris(p-tolylsulfonyl)diethylenetriamine 1 (Scheme 1). Compound1 was synthesized as described in the literature [24]. Elementalanalysis and mass spectral data of 3 were satisfactory: 676.2[M+Na]+. Compound 3 was characterized by NMR and IR spectros-copy techniques. In the 1H NMR (DMSO-d6) spectrum of 3, the NHgroup of 1 had disappeared, as expected, and a new signal atd = 4.87 (br. s, 2H, OH) appeared. The proton-decoupled 13C NMRspectrum of 3 indicates the presence of the corresponding carbonatoms at d = 59.9 (CH2OH) and 49.8 (CH2N). The IR spectrum of 3was easily verified with the disappearance of N–H and the pres-ence of O–H stretching vibrations at 3390 cm�l. The difference be-tween the IR spectra of 3 and 1 is clear from the absence ofcharacteristic vibrations such as N–H.

3,6,9-Tris(p-tolylsulfonyl)-1,11-bis(3,4-dicyanophenoxy)-3,6,9-triazaundecane (5) was prepared by the reaction of 4-nitrophthalo-nitrile and 3 in the presence of K2CO3 in dry DMF. Final purificationof the bisphthalonitrile derivative by recrystallization afforded 5,for which elemental analysis and ES+ mass spectral data were sat-isfactory m/z: 907.2 [M+H]+, 751.1 [M-Ts]+. In the 1H and 13C NMRspectra of 5, the OH groups of compound 3 disappeared and nitrilecarbon atoms appeared as expected. The disappearance of O–H andthe presence of the C„N functional group at 2232 cm-1 in the IRspectrum of compound 5 confirm the formation of the desiredcompound 5.

The metal-free phthalocyanine polymer 6 was synthesized byheating a mixture of 5, DBU and amyl alcohol in a Schlenk tube.Model compound 6a, containing phthalocyanine units and suitableimido end groups, was prepared to use its characteristic data foranalysis of the polymerization degree. The cyano end groups ofthe metal-free phthalocyanine were converted into imido endgroups by treating 6 with conc. H2SO4, and 6a was obtained. TheIR spectrum of polymer 6 is slightly broadened and reduced inintensity, which can be attributed to the difficulty in grinding thesample to a small particle size and the polymeric structure. Thepeaks at 3294 and 1035 cm�1 are the characteristic metal-freephthalocyanine N–H stretching and pyrrole ring vibration bands.A weak –C@N– absorption at 1629 cm�1 was detected. Elemental

HO

N

Ts

N

Ts

N HO

Ts

CN

CNO2N

2+N

Ts

N

Ts

N

Ts

H H O O

O

+165 °CN2(g)

CH3OH

1 2

2

ON

Ts

N

Ts

NO

Ts

NC

NC CN

CN

43

Dry K2CO3

Dry DMF

50 °C

5

N2(g)

R R

N

NNN

N

N

N

N

M

N

NNN

N

N

N

N

M

R

R

O

N Ts

N

TsN

O

Ts

O

N Ts

N

TsN

O

Ts

ON

Ts

N

Ts

NO

Ts

ON

Ts

N

Ts

NO

Ts

N

O

O

H (6a-10 )

Compound M

6 2H7 Zn8 Cu

CoNi

R: C N (6)

R:9

10

Scheme 1. Synthesis of bisphthalonitrile 5 and polymers 6–10.

Table 1Wavelength and absorption coefficients of the UV-Vis spectra of the polymers.

Compound M Solvent k (nm)/(log e) Ratioa UV-Vis

(6) 2H Pyridine 704(4.29) 674(4.28) 648(4.12) 616(4.02) 396(4.03) 334(4.39) 1.02H2SO4 888(3.92) 828(3.98) 731(3.19) 499(3.37) 307(4.05) 242(4.60) 1.17

(7) Zn Pyridine 684(4.24) 618(3.71) 358(4.07) 310(3.69) 0.87H2SO4 828(3.86) 733(2.26) 523(2.73) 311(3.57) 219(4.26) 1.10

(8) Cu Pyridine 682(4.13) 618(3.83) 346(3.98) 305(3.79) 0.92H2SO4 834(4.06) 738(2.91) 515(1.52) 307(3.56) 240(4.21) 1.04

(9) Co Pyridine 676(4.22) 615(3.89) 333(4.35) 314(4.36) 1.03H2SO4 812(4.13) 723(3.71) 503(2.75) 301(4.51) 242(4.60) 1.11

(10) Ni Pyridine 676(4.26) 624(4.12) 330(4.26) 314(4.37) 1.02H2SO4 812(4.21) 722(3.35) 503(2.66) 414(3.23) 308(4.17) 240(4.12) 0.98

a Intensity ratio of absorption B bands at k = 219–334 nm and Q bands at k = 676–888 nm (C = 1.0 � 10�4 g/L in H2SO4 and 1.0 � 10�4 g/L in pyridine).

A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276 2271

2272 A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276

analysis was satisfactory. In the IR spectra for 6a, the disappear-ance of the peak at 2225 cm�1 due to the cyano groups of 6 andthe appearance of new peaks at �1774–1720 cm�1 due to imidogroups supports the conversion of the cyano groups into imidogroups.

The transition metal complexes (7–10) were prepared from thebisphthalonitrile compound 5 and the corresponding metal salt inthe appropriate solvent (Scheme 1). The IR spectra of the metalcomplex polymers (7–10) are very similar, except for the metal-free phthalocyanine polymer 6. The metal-free phthalocyaninepolymer showed an N–H stretching band at 3294 and 1035 cm�1

due to the inner core [25]. These bands disappear in the spectraof the metal complex polymers. These bands are especially benefi-cial for characterization of metal-free phthalocyanine polymers, asthere is little frequency dependence on the ring substitution and

300 400 500 600 700 800

0

1

2in pyridine

109876

Abs

orba

nce

Wavelength,

Wavelength,

Wavelength,

λ (nm)

λ (nm)

λ (nm)

Abs

orba

nce

Abs

orba

nce

200 400 600 800 1000

0.0

0.5

1.0

1.5

2.0

2.5

ZnPc (7)

200 400 600 800 1000

0

1

2

3

4

CoPc (9)

Fig. 1. UV–Vis spectra of polymers (6–10) in pyridine (

they are not overlapped by strong bisphthalonitrile monomerabsorptions [14–16]. The end groups of the metal-free phthalocya-nine polymer were cyano groups (2225 cm�1), while the endgroups of the metal complex polymers were imido groups(�1772–1714 cm�1). The existence of imido groups in the case ofthe metal complex polymers was attributed to the presence ofmoisture during the work-up and the hydrated metal salts. Therewas little shift to longer wavelength numbers in most of the IRbands of the metal complexes with respect to the metal-free ana-logues [14–16,26]. The spectra of the complexes are quite complexand reveal many metal-independent ligand absorptions, and me-tal-N vibrations were expected to appear at 400–100 cm�1, butthey were not detected using KBr pellets [27]. The elemental anal-yses of the metal free (6, 6a) and metal complex polymers (7–10)were satisfactory.

Wavelength,

Wavelength,

Wavelength,

λ (nm)

λ (nm)

200 400 600 800 1000

0

1

2

3

4

Abs

orba

nce

Abs

orba

nce

Abs

orba

nce

H2Pc (6)

200 400 600 800 1000

λ (nm)200 400 600 800 1000

-0.5

0.0

0.5

1.0

1.5

2.0

CuPc (8)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

NiPc (10)

C = 1.0 � 10�4 g/L) and in H2SO4 (C = 1 � 10�4 g/L).

400

400

500

500

600

600

700

700

800

400 500 600 700 800

800

0.00

0.25

0.50

fedcba

a: (7) in pyridine b: a + 0.1 mL NiCl26H2Oc: a + 0.2 mL NiCl26H2Od: a + 0.3 mL NiCl26H2Oe: a + 0.4 mL NiCl26H2Of: a + 0.5 mL NiCl26H2O

a: (7) in pyridine b: a + 0.1 mL CuCl2

. 2H2Oc: a + 0.2 mL CuCl2

. 2H2O d: a + 0.3 mL CuCl2

. 2H2O e: a + 0.4 mL CuCl2

. 2H2O f: a + 0.5 mL CuCl2

. 2H2O

Abso

rban

ceAb

sorb

ance

Abso

rban

ce

Wavelength. λ (nm)

0

1

2f

e

d

c

b

a

Wavelength (nm)

Wavelength (nm)

0.0

0.1

0.2

0.3

0.4

0.5

f

a: (7) in pyridine b: a + 0.1 mL Co(NO3)26H2Oc: a + 0.2 mL Co(NO3)26H2Od: a + 0.3 mL Co(NO3)26H2Oe: a + 0.4 mL Co(NO3)26H2Of : a + 0.5 mL Co(NO3)26H2Oe

d

c

b

a

Fig. 2. Changes in the visible spectra of 7 in pyridine (C = 1.0 � 10�4 g/L) after theaddition of NiCl2�6H2O, CuCl2�2H2O and Co(NO3)2�6H2O solutions in methanol(C = 1.0 � 10�4 M).

A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276 2273

It is very difficult to determine the molecular weight of poly-meric phthalocyanines because of their poor solubility in commonorganic solvents. One possible procedure to determine the degreeof polymerization is IR spectroscopy, by comparison of the inten-sity of the end cyano groups to other ring vibrations. This methodhas been applied to only a few cases [28,29]. We determined thedegree of polymerization after converting the cyano end groupsof the metal-free phthalocyanine polymer into imido end groups,due to the relatively good intensity of C@O imide groups to nitrilegroups. After this, the ratios of the absorption intensities of (Ar–O–C) (etheric groups) of the polymers (�1230 cm�1) to asym. C@Ogroups of the imides (�1714 cm�1) were calculated [compound/log10I1230/I1714: 6a/0.52, 7/1.84, 8/1.23, 9/1.57, 10/1.14]. The poly-merization degrees follow the order: 7 > 9 > 8 > 10 > 6a. On theother hand, the IR spectrum of 6 shows a low degree of polymeri-zation due to the high intensity of the nitrile groups.

The metal-free phthalocyanine 6 and the metal complexes (7–10) gave the typical UV–Vis absorption spectra of phthalocyanines(Table 1). As can be seen in Table 1, there is a shoulder at theslightly higher energy side for polymeric metal-free phthalocya-nine and the metal complexes. The presence of shoulders in theUV–Vis spectra of the polymers corresponds to aggregated ornon-aggregated species in conc. sulfuric acid and pyridine. The me-tal-free phthalocyanine polymer (6) decomposes slowly by hydro-lysis in conc. H2SO4, which is demonstrated by a decrease of theabsorption coefficient at longer wavelengths and also the color ofthe solution turns from green to brown with time. However themetal complex polymers (7–10) were more stable in conc. sulfuricacid than the metal-free polymer and there was no color change inthe case of the metal complexes even after a day. When going fromorganic solvents to concentrated H2SO4, the long-wave absorptionband underwent a significant bathochromic shift, which was dueto weak protonation of the phthalocyanine ring at the meso nitro-gen atoms. The intensity of these absorptions also decreased. TheUV–Vis spectrum of 6 was obtained in pyridine and conc. H2SO4.The electronic absorption spectra of (6–10) in pyridine andH2SO4 at room temperature are shown in Fig. 1. There was a singleQ band for 7–10 while there was a split Q-band, as expected, andtwo strong bands in the visible region for 6 [30]. The split Q-band,which is characteristic for metal-free phthalocyanines, was ob-served at kmax 705 and 674 nm, with shoulders at 647 and617 nm, for (6) indicating the monomeric species; monomeric spe-cies with D2h symmetry show two intense absorptions at around700 nm [30,31]. On the other hand, such split-Q band absorptionsare due to a pp* transition of this fully conjugated 18p electronsystem [32]. In the case of a H2SO4 solution of 6, the primary bandin the visible region was broadened and shifted to longer wave-length (182 nm). In all cases the intensities in the UV (Soret bandtransition) and vis (Q-band transition) spectra were IUV/IVis 61 (Ta-ble 1). This result can be attributed to the absence of poly(isoindol-inine) co-units in all of the polymeric metal complexes (7–10).

UV–Vis titrations were performed with several heavy metal cat-ions (Ni2+, Cu2+, Co2+, Pb2+, Cd2+, Zn2+ and Ag+) to investigate themetal-binding capabilities of complex 7 with triaza-dioxa longperipheral substituents. Firstly, we clarified whether methanolhas any effect or not on the visible spectrum of 7. For this purpose,different amounts of methanol were added to a solution of 7 inpyridine. There was only a little change in the intensities of theQ-bands in the visible absorption spectra of 7 with increasing theamounts of methanol, due to the increasing polarity. Then differentconcentrations of metal salt (e.g. AgNO3, NiCl2�6H2O, Co(N-O3)2�6H2O, Pb(NO3)2, Zn(CH3COO)2�2H2O, Cd(NO3)2�4H2O andCuCl2�2H2O) solutions in methanol (1.0 � 10�4 M) were added tothe solution of the zinc complex 7 in pyridine (1.0 � 10�4 g/L).When we added Ni2+, Cu2+ and Co2+ solutions to the zinc complexsolution, the Q band of 7 broadened and shifted to the low-wave-

length region. The addition of Ni2+, Cu2+ and Co2+ solutions causeda dramatic change due to aggregation in the visible spectrum of 7(Fig. 2). The increasing interactions between the polymer chainsdue to the intermolecular complexation through triazadioxaperipheral units with Ni2+, Cu2+, Co2+ ions forms sandwich typecomplexes and causes the new absorption bands. The new bandscan be attributed to the presence of dimeric and oligomeric phtha-locyanine species. Further addition of Ni2+, Cu2+ and Co2+ solutionscaused no observable effect. On the other hand, when solutions ofPb2+, Cd2+, Zn2+ and Ag+ were added, the intensity of the bands at684 and 618 nm gradually decreased without any shift and nooptical change was observed (Fig. 3). The decrease in the intensity

0.0

0.2

0.4

0.6a: (7) in pyridine b: a + 0.1 mL Ag(NO3)c: a + 0.2 mL Ag(NO3)d: a + 0.3 mL Ag(NO3)e: a + 0.4 mL Ag(NO3)f: a + 0.5 mL Ag(NO3)

f

e

d

c

b

a

Abso

rban

ce

400 500 600 700 800-0.2

0.0

0.2

0.4a: (7) in pyridine b: a + 0.1 mL Cd(NO3)24H2Oc: a + 0.2 mL Cd(NO3)24H2Od: a + 0.3 mL Cd(NO3)24H2Oe: a + 0.4 mL Cd(NO3)24H2Of: a + 0.5 mL Cd(NO3)24H2O

f

e

d

c

b

a

Abso

rban

ce

0.0

0.2

0.4

0.6

a: (7) in pyridine b: a + 0.1 mL Pb(NO3)2c: a + 0.2 mL Pb(NO3)2d: a + 0.3 mL Pb(NO3)2e: a + 0.4 mL Pb(NO3)2f: a + 0.5 mL Pb(NO3)2 f

ed

c

b

a

Abso

rban

ce

Abso

rban

ce

-0.2

0.0

0.2

0.4

a: (7) in pyridine b: a + 0.1 mL Zn(CH3COO)22H2Oc: a + 0.2 mL Zn(CH3COO)22H2Od: a + 0.3 mL Zn(CH3COO)22H2Oe: a + 0.4 mL Zn(CH3COO)22H2Of: a + 0.5 mL Zn(CH3COO)22H2O

f

e

d

c

b

a

400 500 600 700 800Wavelength (nm)

400 500 600 700 800Wavelength (nm)

Wavelength (nm)

400 500 600 700 800

Wavelength (nm)

Fig. 3. Changes in the visible spectra of 7 in pyridine (C = 1.0 � 10�4 g/L) after the addition of AgNO3, Pb(NO3)2, Cd(NO3)2�4H2O and Zn(CH3COO)2 solutions in methanol(C = 1.0 � 10�4 M).

Table 2Thermal properties of the polymers.

Polymer M Tg Initial decompositiontemperature in �C

Main decompositiontemperature in �C

6 2H 42 360 4177 Zn 51 336 3958 Cu 50 358 3789 Co 56 310 37110 Ni 45 341 367

2274 A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276

of the bands can be attributed to the dilution effect and the veryweak or non-coordination of the N and O atoms to Pb2+, Cd2+,Zn2+ and Ag+ ions, thus leaving the Pb(NO3)2, Cd(NO3)2�4H2O,Zn(CH3COO)2�2H2O and AgNO3 units only loosely coordinated viaoxygen and nitrogen donors.

The powder samples of the polymeric metal-free phthalocya-nine and metal complexes were pressed in the form of pellets of10 mm diameter and thickness ranging from 1 to 3 mm for AC con-ductivity measurements. The surfaces of the polymers were cov-ered with silver paste to form electrodes. Then, the capacitanceand the dielectric loss factor of each sample were measured be-tween 10 kHz and 1 MHz frequency range at room temperature

104 105 106

0

2x10-5

4x10-5

6x10-5

8x10-5

104 105

1x10-7

2x10-7

3x10-7

4x10-7

5x10-7

σ ac (S

/m)

log f (Hz)

6789 10

Fig. 4. The frequency versus AC conductivity of polymers (6–10) at roomtemperature. Fig. 5. DTA/TG thermograms of H2Pc (6), ZnPc (7) and CoPc (9).

Fig. 6. DSC thermograms of CuPc (8) and NiPc (10).

A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276 2275

by using a LCR meter (Agilent 4284A). From the measured values ofthe dielectric permittivity and the dielectric loss factor, the AC con-ductivity was calculated. The conductivity values correspond tothose of semi-conductive materials encountered in most of thesubstituted phthalocyanine derivatives [33]. The dielectric permit-tivity of the samples was calculated using the relation;

C ¼ e0erAd

where C is the capacitance of the sample, e0 is the permittivity of air,A is the surface area of the sample, d is the thickness of the sampleand er is the dielectric permittivity of the sample. The frequencyversus AC conductivity graph was plotted at room temperatureand is depicted in Fig. 4. From the figure, it can be seen that the va-lue of the AC conductivity does not show a clear variation at lowerfrequencies at room temperature. That is, there is no appreciablevariation in AC conductivity of the polymers at low frequencies(<105 Hz), above 105 Hz, there is a rapid increase with frequency.This is in accordance with the theory of AC conduction in amor-phous materials, which predicts that for polaron transport or otherhopping modes, the AC conductivity will increase monotonicallywith the increased frequency of the applied field. The AC conductiv-ity, dielectric permittivity, and dielectric loss can be related by thefollowing equation;

rAC ¼ 2pf e0er tan d

where e0 is the permittivity of air, er is the dielectric permittivity ofthe sample, f is the frequency and tan d is the dielectric loss [34]. Onthe other hand, the AC conductivity of the metal-free polymer washigher than those of the metal complexes. This can be due to theoxygen-susceptible NH group of the metal-free polymer 6. TheNH groups should be partially oxidized in air. In the metal com-plexes, the NH groups were no longer sensitive to O2 after complex-ation with transition metal ions [17].

Thermal properties of the metal-free and metal complex poly-mers were investigated by DSC and DTA/TG. The phthalocyaninepolymers are resistant to thermal oxidation [35]. The DTA andDSC curves exhibit exothermic changes for all polymers in the re-gion investigated [36], the curves do not show melting points. Noobvious correlation between the transition metal ion in the phtha-locyanine ring and the corresponding main decomposition temper-atures could be established, while the initial decompositiontemperature decreased in the order: 6 > 8 > 10 > 7 > 9 (Table 2).The higher stability of 6 as compared with the polymeric metal

complexes (7–10) could obviously be traced to the interaction ofthe polar nitrile groups in the solids. DSC and DTA/TG thermo-grams of all the polymers can be seen in Figs. 5 and 6. The glasstransitions were found as 42, 51, 50, 56 and 45 �C for 6, 7, 8, 9and 10, respectively. All samples showed a weight loss below200 �C, probably due to volatiles evaporation (N2, O2, CO2 andH2O) or low temperature degradation of unstable chemical frag-ments in the samples. At higher temperatures, between 350 and400 �C, the main degradation step is visible, with a weight lost ofabout 43–54% for all samples. All the adsorbed gases and decom-posed groups in the samples were identified by MS as: 17 (NH3),18 (H2O), 28 (N2), 32 (O2) and 44 (CO2) below 200 �C, 27 (HCN),44 (CO2) and 91 (toluene) above 400 �C.

4. Conclusion

We have presented the synthesis and characterization of thenew bisphthalonitrile 5 and polymeric metal-free (6) phthalocya-nine and metal complexes (7–10) with diazatrioxa peripheralunits. The polymers (6–10) were prepared using a bisphthalonitrilemonomer and the appropriate precursors. No obvious correlationbetween the transition metal ion in the phthalocyanine ring andthe corresponding main decomposition temperatures could beestablished. The electrical conductivities of the polymeric materi-als measured in air at room temperature and were found to be10�6–10�5 S m�1 in air. The polymeric zinc complex 7 had a clearaggregation tendency with the addition of Ni2+, Cu2+ and Co2+ solu-tions. On the other hand, there was no shift or optical change withthe addition of Pb2+, Cd2+, Zn2+ and Ag+ solutions.

Acknowledgements

This study was supported by the Scientific and TechnicalResearch Council of Turkey (TUBITAK), Project No. TBAG-2453(104T065) (Ankara, Turkey).

References

[1] M. Hanack, H. Heckmann, R. Polley, in: E. Schaumann (Ed.), Houben-WeylMethods of Organic Chemistry, fourth ed., vol. E 9d, Georg Thieme Verlag,Stuttgart, 1998, p. 717.

[2] J. Simon, P. Bassoul, Design of Molecular Materials: SupramolecularEngineering, VCH, Weinheim, 2000.

[3] D. Schlettwein, D. Wohrle, N.I. Jaeger, J. Electrochem. Soc. 136 (1989) 2882.[4] J. Simon, C. Sirlin, Pure Appl. Chem. 61 (1989) 1625.

2276 A. Bilgin et al. / Polyhedron 28 (2009) 2268–2276

[5] M.J. Cook, N.B. McKeown, J.M. Simmons, A.J. Thomson, M.F. Daniel, K.J.Harrison, R.M. Richardson, S.J. Roser, J. Mater. Chem. 1 (1991) 121.

[6] O.L. Kaliya, E.A. Lukyanets, G.N. Vorozhtsov, J. Porphyrins Phthalocyanines 3(1999) 592.

[7] F. Hacıvelioglu, M. Durmus�, S. Yes�ilot, A.G. Gürek, A. Kılıç, V. Ahsen, DyesPigments 79 (2008) 14.

[8] X. Ding, S. Shen, Q. Zhou, H. Xu, Dyes Pigments 40 (1999) 187.[9] Z. Odabas�, A. Altındal, B. Salih, M. Bulut, Ö. Bekaroglu, Tetrahedron Lett. 48

(2007) 6326.[10] J.E. van Lier, in: D. Kessel (Ed.), Photodynamic Therapy of Neoplastic Diseases,

vol. 1, CRC Press, Boca Raton, FL, 1990.[11] YuA Kokshorov, A.I. Sherle, A.N. Tikhonov, Synth. Met. 149 (2005) 19.[12] D. Wöhrle, Macromol. Rapid Commun. 22 (2001) 68.[13] N.B. McKeown, J. Matter. Chem. 10 (2000) 1979.[14] D. Wöhrle, U. Marose, R. Knoop, Makromol. Chem. 186 (1985) 2209.[15] A. Bilgin, Ç. Yagcı, U. Yıldız, Macromol. Chem. Phys. 206 (2005) 2257.[16] A. Bilgin, A. Mendi, U. Yıldız, Polymer 47 (2006) 8462.[17] J. Simon, J.J. Andre, in: J.M. Lehn, C.W. Rees (Eds.), Molecular Semiconductors,

Springer-Verlag, Berlin, 1985, p. 136.[18] A. Bilgin, Ç. Yagcı, A. Mendi, U. Yıldız, Polyhedron 26 (2007) 617.[19] A. Bilgin, Y. Gök, Supramol. Chem. 18 (2006) 491.[20] A. Bilgin, B. Ertem, Y. Gök, Supramol. Chem. 17 (2005) 277.[21] A. Bilgin, Ç. Yagcı, A. Mendi, U. Yıldız, J. Appl. Polym. Sci. 110 (2008) 2115.

[22] A. Bilgin, B. Ertem, Y. Gök, Eur. J. Inorg. Chem. (2007) 1703.[23] G.J. Young, W. Onyebuagu, J. Org. Chem. 55 (1990) 2155.[24] T.J. Atkins, J.E. Richman, W.F. Oettle, Org. Synth. 58 (1978) 86.[25] A.W. Snow, J.R. Griffith, N.P. Marullo, Macromolecules 17 (1984) 1614.[26] D. Wöhrle, E. Preubner Makromol. Chem. 186 (1985) 2189.[27] K. Nakomato, Infrared Spectra of Inorganic and Coordination Compounds,

second ed., Wiley, New York, 1970.[28] D. Wöhrle, B. Schulte, Makromol. Chem. 189 (1988) 1167.[29] D. Wöhrle, R. Benters, O. Suvorova, G. Schnurpfeil, N. Trombach, T. Bogdahn-

Rai, J. Porphyrins Phthalocyanines 4 (2000) 491.[30] _I. Özçes�meci, A._I. Okur, A. Gül, Dyes Pigments 75 (2007) 761.[31] E.A. Cuellar, T.J. Marks, Inorg. Chem. 20 (1981) 3766.[32] Y. Gök, H. Kantekin, A. Bilgin, D. Mendil, _I. Degirmencioglu, Chem. Commun. 3

(2001) 285.[33] G. Gümüs�, R.Z. Öztürk, V. Ahsen, A. Gül, Ö. Bekaroglu, J. Chem. Soc., Dalton

Trans. 16 (1992) 2485.[34] S. Saravanan, C.J. Mathai, M.R. Anantharaman, S. Venkatachalam, P.V.

Prabhakaran, J. Appl. Polym. Sci. 91 (2004) 2529.[35] A.D. Delman, J.J. Kelly, A.A. Stein, F.B. Simms, Thermal analysis, Proceedings of

the International Conference 2nd, vol. 1, Academic Press, New York, 1969, p.539.

[36] H. Shirai, K. Kobayashi, Y. Takemae, A. Suzuki, O. Hirabaru, N. Hojo, Makromol.Chem. 180 (1979) 2073.