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Polyhedron 26 (2007) 617–625

Synthesis and characterization of new polymeric phthalocyaninessubstituted with diaza-18-crown-6 macrocycles through

ethyleneoxy bridges

Ahmet Bilgin a,*, Cigdem Yagcı a, Ays�egul Mendi b, Ufuk Yıldız b

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

Received 18 July 2006; accepted 24 August 2006Available online 5 September 2006

Abstract

A tetranitrile monomer was synthesized by nucleophilic aromatic substitution of N,N 0-bis(2-hydroxyethyl)-4,13-diaza-18-crown-6onto 4-nitrophthalonitrile. A series of polymeric metal-free and metallophthalocyanine (M = 2H, Zn, Cu, Co and Ni) polymers was pre-pared by polymeric tetramerization reaction of the tetranitrile monomer with proper materials. The electrical conductivities of the poly-meric phthalocyanines measured as gold sandwiches were found to be �10�9–10�4 S cm�1 in a vacuum and in argon. The extractionability of the metal-free polymeric phthalocyanine was evaluated in tetrahydrofuran using several alkali metal picrates such as Li+,Na+, K+ and Cs+. The extraction affinity of the metal-free polymeric phthalocyanine for K+ was found to be highest in the heteroge-neous solid–liquid phase extraction experiments. The disaggregation property of the metal-free polymeric phthalocyanine was investi-gated with sodium, potassium and ammonium ions and methanol. All the novel compounds were characterized by using elementalanalysis, UV–Vis, FT-IR, NMR and MS spectral data and DTA/TG.� 2006 Elsevier Ltd. All rights reserved.

Keywords: Bisphthalonitrile; Diaza-18-crown-6; Electrical conductivity; Extraction; Polymeric phthalocyanine

1. Introduction

Phthalocyanines have found practical applications in awide range of high technology fields such as nonlinearoptics, photosensitizers, gas sensors, catalysts, liquid crys-tals, optical data storage, sensitizers for photodynamictherapy of cancer, electrodes in fuel cell, photoelectric con-version materials in solar cells, and laser service substances,among others [1–3]. A great number of remarkable applica-tions of phthalocyanines arise from their unique 18p elec-tron conjugated aromatic cloud, which makes thempresent high thermal and chemical stability and remarkablephotoelectric properties [4].

0277-5387/$ - see front matter � 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.poly.2006.08.027

* Corresponding author. Tel.: +90 262 3032438; fax: +90 262 3032403.E-mail address: abilgin@kou.edu.tr (A. Bilgin).

A combination of a phthalocyanine with a polymer orincorporation of a phthalocyanine into a polymer is a pow-erful tool for designing materials with interesting properties[5]. Polymeric phthalocyanines were mainly prepared viapolycyclotetramerization reactions of bifunctional mono-mers such as various nitriles [6–21] or tetracarboxylic acidderivatives [22–25] in the presence of metal salts or metals.We have previously synthesized novel phthalocyaninescarrying various macrocyclic groups and polymeric phthalo-cyanines [26].

In the present work, metal-free and metallophthalocya-nine polymers which contain ethyleneoxy diaza-18-crown-6moieties were synthesized and characterized. The electricalconductivities of the polymers as Au/MPc/Au sandwichesin a vacuum and in argon atmosphere were examined.The viscosity properties of all the polymers and alkali

618 A. Bilgin et al. / Polyhedron 26 (2007) 617–625

metal extraction ability and disaggregation property of themetal-free polymeric phthalocyanine were investigated.

2. Experimental

2.1. Materials

Phosphorus pentoxide (P2O5), 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU), ethyl alcohol, n-pentanol, dimethyl-formamide (DMF), tetrahydrofuran (THF), chloroform,dichloromethane, petroleum ether, quinoline, sulphuricacid, hydrochloric acid, pyridine, acetone, 1,2-bis(2-iodo-ethoxy)ethane, sodium iodide, sodium thiosulfate, acetoni-trile, sodium carbonate, dioxane, ethylene oxide, methanol,1,2-(2-aminoethoxy)ethane were received from Merck andused as supplied. Cesium carbonate (Cs2CO3) was receivedfrom Merck and used after drying in oven at 250 �C for36 h. All organic solvents were dried and purified asdescribed by Perrin and Armarego [27]. 4-Nitrophthalo-nitrile was synthesized as described in the literature [28].1,10-Diaza-18-crown-6 was synthesized according to theliterature [29].

2.2. Measurements

Melting points of the compounds were determined withan electrothermal melting point apparatus and were uncor-rected. 1H NMR spectra were recorded on a Varian Mer-cury Plus 300 MHz spectrometer with CDCl3 as solventand tetramethylsilane as the internal standard. 13C NMRspectra were recorded on a Varian Mercury Plus 75 MHzspectrometer with CDCl3 as the solvent and tetramethylsi-lane as the internal standard. Transmission IR spectra ofsamples were recorded on a FTIR spectrophotometer(Shimadzu FTIR-8201 PC) with the samples in KBr pellets.Optical spectra in the UV–Vis region were recorded with amodel Shimadzu 1601 UV–Vis spectrometer using stan-dard cuvettes with a fixed 1 cm pathlength at room temper-ature. The d.c. conductivity was measured by a Autolab 30Voltammetry-FRA 2 frequency analyser. The frequencyrange was of 100 Hz–1 MHz and applied amplitude (rms)was 10 mV. Mass spectra were measured on a VarianMAT 711 and on Micromass Quatro LC/ULTIMALC-MS MS spectrometers. The elemental analysis of thecompounds was determined on a CHNS-932 LECO instru-ment. The metal contents of the metallophthalocyaninepolymers were determined with a Unicam 929 AA spectro-photometer in solutions prepared by decomposition of themetallophthalocyanines in conc. sulfuric acid and conc.nitric acid solution followed by digestion in conc. hydro-chloric acid solution and deionize water. Differential ther-mal analysis (DTA/TG) was performed on a Linseis L81instrument in air atmosphere with a heating rate of10 �C/min in a temperature range of 50–750 �C. Intrinsicviscosities of freshly prepared dilute solutions of phthalo-cyanine polymers were measured in conc. H2SO4 at 25 �Cby use of an Ubbelohde viscometer.

2.3. Synthesis

2.3.1. Preparation of N,N 0-bis(2-hydroxyethyl)-4,13-diaza-

18-crown-6 (3)

A mixture of 1,10-diaza-18-crown-6 (3 g, 11.44 mmol)and methanol (20 mL) was charged into a 250-mL three-necked flask on ice-bath. Ethylene oxide (2.7 mL) wascooled to�20 �C and then added dropwise into the reactionflask over a period of 10 min. After adding, ice-bath waschanged with oil-bath. The reaction mixture was refluxedfirst for 4 h with a condenser which was cooled to �20 �Cand then 3 more hours with an ordinary condenser undernitrogen atmosphere at 65–70 �C. The reaction was endedand the solvent, methanol, was evaporated. The residuewas distilled under vacuum at 200–210 �C (0.10-mm Hg)to yield pale yellow product. Refractive index of the prod-uct was 1.4937 at 20 �C. After the product was cooled to�10 �C, some part of the product was precipitated as whitecrystals. They were mechanically separated from the motherliquor; m.p., 49–51 �C.

Compound 3: yield, 2.88 g (72%). Anal. Calc. forC16H34N2O6: C, 54.84; H, 9.78; N, 7.99. Found: C, 55.01;H, 9.64; N, 8.12%. IR (KBr): mmax (cm�1): 3327 (s, OH),2955–2810 (–CH2–), 1483, 1477, 1442, 1361, 1353, 1255,1126–1045 (s, CH2O–), 954, 875. 1H NMR (CDCl3):d = 4.43 (s, broad, 2H, D2O exchangeable, OH), 3.69 (q, J

7.11 Hz, 4H, NCH2CH2OH), 3.53 (s, 8H, –OCH2CH2O),3.29 (t, J 6.48 Hz, 8H, NCH2CH2O), 2.66 (t, J 7.11 Hz,4H, NCH2CH2OH), 2.50 (t, J 6.44 Hz, 8H, NCH2CH2O).13C NMR (CDCl3): d = 70.34 (–OCH2CH2O), 66.75(NCH2CH2O), 60.14 (NCH2CH2OH), 56.43 (NCH2CH2-OH), 54.15 (NCH2CH2O). MS (Electron impact, EI), m/z(%): 369.08 (3.12) [M + H2O+1]+, 352.22 (1.23) [M + 2]+,351.25 (1.90) [M + 1]+, 350.25 (1.8) [M]+, 349.11 (1.02)[M � 1]+, 333.31 (1.24) [M � OH]+, 319.36 (100.00)[M � CH2OH]+, 289.17 (23.36) [M + 1 � 2CH2OH]+,275.42 (20.13) [M + 1 � C3H8O2]+, 188.32 (10.29), 176.20(10.81), 162.45 (25.52), 146.43 (20.73), 132.09 (18.32),114.28 (35.67), 100.39 (40.56).

2.3.2. Preparation of N,N 0-bis (2-oxyethyl-phthalonitrilo)-

4,13-diaza-18-crown-6 (5)

A mixture of 4-nitrophthalonitrile (2.47 g, 14.28 mmol)and dry DMF (10 mL) was charged into a 200-mL three-necked flask and stirred at room temperature undernitrogen inert atmosphere. N,N 0-Bis(2-hydroxyethyl)-4,13-diaza-18-crown-6 (2.5 g, 7.14 mmol) was added to thesolution and the temperature was increased up to 50 �C.Powdered Cs2CO3 (7.12 g, 21.42 mmol) was added to thesystem in five equal portions at 45 min intervals with effi-cient stirring and the reaction system was stirred at thesame temperature (50 �C) for 7 days. Aliquots were takenand checked periodically for completeness of the reactionsand observed by thin layer chromatography (TLC)(8:2 chloroform:methanol). The reaction system was cooledand poured into ice-water and then mixed for 3 h. Themixture was extracted with chloroform (4 · 50 mL) and

A. Bilgin et al. / Polyhedron 26 (2007) 617–625 619

organic phase was dried over MgSO4. Chloroform wasevaporated and oily brown crude product was obtained.The yield was recrystallized from a mixture ofethanol:diethyl ether (3:1; v/v) and dried again under vac-uum over P2O5. The final brown solid 5 was soluble inchloroform, DMF, DMSO, pyridine, THF anddichloromethane.

Compound 5: yield, 3.96 g (92%); m.p., 156 �C. Anal.Calc. for C32H38N6O6: C, 63.77; H, 6.36; N, 13.94. Found:C, 63.94; H, 6.22; N, 13.65%. IR (KBr): mmax (cm�1): 3040(aromatic @CH), 2920–2865 (aliphatic CH2), 2230(C„N), 1601 (aromatic AC@CA), 1420, 1389, 1260 (Ar–O–C), 1126–1049 (CH2–O–CH2), 943 and 881. 1H NMR(CDCl3): d = 7.99 (d, J 8.00 Hz, 2H, ArH), 7.53 (d, J8.53 Hz, 2H, ArH), 7.44 (dd, J 9.30 Hz, 2H, ArH), 4.18 (t,J 7.23 Hz, 4H, N–CH2–CH2O–Ar), 3.65 (s, 8H, –OCH2-CH2O), 3.11 (t, J 6.82 Hz, 8H, NCH2CH2O), 2.80 (t, J

7.23 Hz, 4H, NCH2CH2O–), 2.55 (t, J 6.82 Hz, 8H,NCH2CH2O). 13C NMR (CDCl3): d = 162.92 (C4), 135.42(C6), 121.95 (C5), 119.81 (C3), 117.32 (C2), 116.48 (C7),115.96 (C8), 110.00 (C1), 71.39 (C9), 69.58 (C13), 67.37(C12), 55.49 (C11), 55.08 (C10). MS, m/z (%): 736.21 (7.17)[M + Cs + 1]+, 603.74 (10.26) [M + 1]+, 602.58 (11.42)[M]+, 527.38 (35.06), 459.25 (12.76) [M � C8H3N2O]+,445.36 (48.17) [M � C9H5N2O]+, 316.43 (60.21)[M � C16H6N4O2]+, 288.12 (100.00) [M � C18H10N4O2]+,188.16 (21.03), 176.78 (16.54), 143.47 (70.73), 127.82(38.34), 114.28 (42.23), 100.02 (31.26).

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

A mixture of compound 5 (0.602 g, 1 mmol), n-penta-nol (5 mL) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)(0.155 g, 1 mmol) was placed in a standard Schlenk tubeunder nitrogen atmosphere and degassed several times.The temperature was gradually increased up to 90 �Cand degassed again with nitrogen. Then the reaction mix-ture was stirred at 145 �C for 12 h. After the reactionmixture was cooled and decanted, the residue was stirredwith methanol:petroleum ether mixture (10 mL, 1/1; v/v).The product 6 was filtered off, washed with DMF, meth-anol, acetone and diethyl ether and dried in air. The finaldark green solid 6 was soluble in H2SO4, hot pyridineand poorly soluble in chloroform, dichloromethane andTHF.

Compound 6: yield, 0.43 g; m.p. >300 �C. Anal. Calc. for(C128H154N24O24)n (2411.16): C, 63.72; H, 6.43; N, 13.93.Found: C, 63.48; H, 6.65; N, 14.12%. IR (KBr): mmax

(cm�1): 3275 (N–H), 3055 (aromatic @CH), 2970–2840(CH2), 2223 (C„N), 1642 (AC@NA), 1598 (aromaticAC@CA), 1469, 1380, 1265 (Ar–O–C), 1130–1040 (CH2–O–CH2), 1030, 960, 853, 682 and 530 cm�1. 1H NMR (pyr-idine-d5): d = 8.42–8.18 (m, br, 96H, ArH), 4.34 (t, J

7.15 Hz, 64H, N–CH2–CH2O–Ar), 3.54 (s, 128H, –OCH2-CH2O), 3.22 (t, J 6.52 Hz, 128H, NCH2CH2O), 2.87 (t, J

7.15 Hz, 64H, NCH2CH2O–), 2.57 (t, J 6.52 Hz, 128H,NCH2CH2O). MS (FAB positive), m/z: 9645.87 [M + 1]+.

2.3.4. Preparation of Zn-containing polymer (7)

A mixture of bisphthalonitrile compound 5 (0.602 g,1 mmol), zinc acetate dihydrate [Zn(CH3COO)2 Æ 2H2O](0.112 g, 0.5 mmol) and amyl alcohol (5 mL) was put in aflask and the temperature was increased up to 160 �C. DBU(0.08 g, 0.08 mL, 0.5 mmol) was added dropwise with a syr-inge to the system at the same temperature. The reactionwas treated at 160 �C for 12 h under reflux and nitrogen atmo-sphere. After cooling, 10 mL of methanol–water mixture (1:1,v/v) was added to the system and stirred for 45 min. The crudeproduct was filtered and washed with methanol, DMF,distilled water, petroleum ether and acetone. The final greenproduct 7 was dried under vacuum over P2O5 at 100 �C.

Compound 7: yield, 0.40 g; m.p. >300 �C. Anal. Calc. for(C128H156N20O32Zn)n (2549.05): C, 60.24; H, 6.16; N,10.98; Zn, 2.56. Found: C, 60.45; H, 6.37; N, 10.69; Zn,2.67%. IR (KBr): mmax (cm�1): 3390 (imide N–H), 3054(aromatic @CH), 2990–2789 (CH2), 1770 (sym. C@O),1720 (asym. C@O), 1640 (AC@NA), 1598 (aromaticAC@CA), 1485, 1421, 1326, 1254 (Ar–O–C), 1160–1040(C–O–C), 957, 842 and 650 cm�1.

2.3.5. Preparation of Cu-containing polymer (8)

A mixture of bisphthalonitrile compound 5 (0.602 g,1 mmol), Cu(CH3COO)2 Æ H2O (0.100 g, 0.5 mmol) and amylalcohol (3 mL) was put in a flask. The temperature wasincreased up to 160 �C and degassed three times under nitro-gen atmosphere. Then, DBU (0.08 mL, 0.08 g, 0.5 mmol) wasadded drop by drop with a syringe into the system. The reac-tion was treated at 160 �C for 12 h under reflux and nitrogenatmosphere. The reaction mixture was cooled, diethyl ether–methanol mixture (5 mL, 1:1) was added and stirred for 1 h.The mixture was filtered and the solid part was washed withdistilled water, DMF, ethanol and diethyl ether. The finalproduct 8 was dried under vacuum over P2O5 at 100 �C.

Compound 8: yield, 0.38 g; m.p. >300 �C. Anal. Calc. for(C128H156N20O32Cu)n (2548.05): C, 60.28; H, 6.17; N,10.98; Cu, 2.49. Found: C, 60.51; H, 6.43; N, 11.17; Cu,2.26%. IR (KBr): mmax (cm�1): 3360 (imide N–H), 3062(aromatic @CH), 2980–2853 (CH2), 1774 (sym. C@O),1713 (asym. C@O), 1636 (AC@NA), 1601 (aromaticAC@CA), 1493, 1428, 1330, 1262 (Ar–O–C), 1155–1020(C–O–C), 964, 856 and 590 cm�1.

2.3.6. Preparation of Co-containing polymer (9)

A mixture of bisphthalonitrile compound 5 (0.602 g,1 mmol), dry quinoline (2 mL) and CoCl2 Æ 6H2O (0.120 g,0.5 mmol) was kept in a flask and degassed three times withnitrogen. The reaction mixture was treated at 220 �C underreflux and nitrogen inert atmosphere. After 24 h of stirring,the reaction mixture was cooled and then diethyl ether(25 mL) was added and then filtered off. The solid partwas washed with methanol:diethyl ether mixture (20 mL,1:1), DMF, hot ethanol, acetone and filtered off. The finalproduct 9 was dried under vacuum over P2O5 at 100 �C.The final green product 9 was soluble in H2SO4 and poorlysoluble in pyridine.

Table 1Alkaline metal picrate extractions for 6a under solid/liquid two-phaseconditions

Metal ion Extractability of the metal-freepolymeric phthalocyanine (6) (%)b

kmax (nm) ofmetal picrate

Li+ 6.01 ± 0.01 362Na+ 77.17 ± 0.01 356K+ 94.25 ± 0.01 364Cs+ 22.16 ± 0.01 354

a Temperature 25 ± 1 �C; THF phase (10 mL), [picrate] = 3.0 · 10�3 M;host molecule = 20 mg.

b Average and standard deviation for three independent measurements.

620 A. Bilgin et al. / Polyhedron 26 (2007) 617–625

Compound 9: yield, 0.31 g; m.p. >300 �C. Anal. Calc. for(C128H156N20O32Co)n (2544.05): C, 60.39; H, 6.18; N, 11.00;Co, 2.32. Found: C, 60.17; H, 6.41; N, 11.23; Co, 2.64%. IR(KBr): mmax (cm�1): 3400 (imide N–H), 3048 (aromatic@CH), 2920–2796 (CH2), 1776 (sym. C@O), 1718 (asym.C@O), 1641 (AC@NA), 1612 (aromatic AC@CA), 1500,1435, 1323, 1265 (Ar–O–C), 1148–1032 (C–O–C), 972, 870and 623 cm�1.

2.3.7. Preparation of Ni-containing polymer (10)

A mixture of bisphthalonitrile compound 5 (0.602 g,1 mmol), dry quinoline (1.5 mL) and NiCl2 Æ 6H2O(0.122 g, 0.5 mmol) was charged in a standard Schlenk tubeand degassed three times with nitrogen. The temperaturewas increased up to 220 �C and treated for 24 h underreflux and nitrogen inert atmosphere. The system wascooled to room temperature and methanol:water (10 mL,1:1; v/v) mixture was added to the system and stirred atroom temperature for 1 h. The product was filtered offand washed with DMF, methanol, distilled water, petro-leum ether. The final green product 10 was dried under vac-uum over P2O5 at 100 �C. The product 10 was soluble inH2SO4 and poorly soluble in pyridine.

Compound 10: yield, 0.37 g; m.p. >300 �C. Anal. Calc. for(C128H156N20O32Ni)n (2543.05): C, 60.40; H, 6.18; N, 11.01;Ni, 2.31. Found: C, 60.64; H, 6.06; N, 11.35; Ni, 2.52%. IR(KBr): mmax (cm�1): 3413 (imide N–H), 3043 (aromatic@CH), 2925–2875 (CH2), 1772 (sym. C@O), 1710 (asym.C@O), 1642 (AC@NA), 1605 (aromatic AC@CA), 1513,1420, 1325, 1257 (Ar–O–C), 1160–10430 (C–O–C), 974,846 and 610 cm�1.

2.3.8. The conversion of cyano end groups of the metal-free

polymeric phthalocyanine into imido groups (6a)

A sample of the metal-free polymeric phthalocyanine (6)(150 mg) was dissolved in a minimum volume of H2SO4

(96 wt%) at room temperature. After 3–4 h of stirring,the reaction mixture was filtered. The filtrate was pouredinto excess amount of ice-water mixture. The dark greencrude product was washed with distilled water until thewashings were neutral. Then the final product 6a waswashed with ethanol and diethyl ether and dried under vac-uum over P2O5 at 100 �C.

Compound 6a: yield, 0.12 g; m.p. >300 �C. Elementalanalyses (for imide end groups): Anal. Calc. for (C128H158-N20O32)n (2487.14)n: C, 61.77; H, 6.40; N, 11.26. Found: C,61.89; H, 6.26; N, 11.54%. IR (KBr): mmax (cm�1): 3385(imide N–H), 3310 (N–H), 3050 (aromatic @CH), 2980–2852 (CH2), 1772 (sym. C@O), 1720 (asym. C@O), 1629(AC@NA), 1596 (aromatic AC@CA), 1508, 1491, 1448,1324, 1242 (Ar–O–C), 1151–1040 (C–O–C), 975, 940–840,and 543 cm�1.

2.3.9. Metal analysis of the polymeric phthalocyaninesA sample of the metallophthalocyanine polymers (7–10)

(10 mg) was added into concentrated sulfuric acid (2.5 mL)and conc. nitric acid (3.5 mL). The mixture was heated for

2 h at 160 �C in an oil-bath. The solution was firstlydigested in conc. HCl acid solution and then diluted withdeionize water (500 mL). The determination of metal ionswas conducted by atomic absorption measurements.

2.3.10. Measurement of the alkali metal-binding properties

of the polymeric metal-free phthalocyanine

The extraction properties of 6 were investigated undersolid–liquid phase condition by using alkali metal picrates(Li+, Na+, K+ and Cs+) as substrates and measuring byUV–Vis the amounts of picrate in THF phase before andafter treatment with polymers in suspension. Suspensionswere prepared by mixing 25 mg of the polymeric metal-freephthalocyanine (6) and the alkali metal picrate solutions asdescribed in previous article [26g]. The prepared suspen-sions were put in plastic bottles and shaken vigorously for24 h at room temperature. Results and experimental condi-tions are reported in Table 1. In the absence of host 6, blankexperiment, no metal ion picrate extraction was detected.The extractability was determined based on the absorbanceof picrate ion in the THF suspensions. The extractabilitywas calculated by using the following equation:

Eð%Þ ¼ ½ðA0 � AÞ=A0� � 100

where A0 is the absorbance in the absence of ligand. A de-notes the absorbance in THF suspension phase afterextraction.

3. Results and discussion

The synthesis of the N,N 0-bis(2-hydroxyethyl)-4,13-diaza-18-crown-6 (3) was performed by starting with4,13-diaza-18-crown-6 (1) and ethylene oxide (2) in metha-nol (Scheme 1). The yield (72%) was higher than the knownprocedure (51%) [29] and the product was partly solid(m.p., 49–51 �C) while it was said to be oily in the literaturereference. Elemental analysis and mass spectral data of 3

were satisfactory: 350.25(1.8) [M]+. In 1H NMR (CDCl3)spectrum of 3, NH group of compound 1 disappeared asexpected. 1H NMR spectrum of 3 showed new signal atd = 4.43 (s, broad, 2H, OH) and also the proton-decoupled13C NMR spectrum of 3 indicates the presence of primaryalcohol carbon atoms at d = 60.14 (NCH2CH2OH) and56.43 (NCH2CH2OH), respectively. The IR spectrum of 3

was easily verified with the disappearance of N–H and

O

O

N

O

O

N HHO

2+ HO

O

O

N

O

O

NOH

O

O

N

O

O

NO

CN

CN

O

NC

NC 1

23

4

56 7

89

10

11

12

13

(1) (2) (3)

(5)

Dry CH3OH

RefluxN2(g)

CN

CNO2N

2+

(4)

Dry DMFCs2CO3

50 ºCN2(g)

R R

N

NNN

N

N

N

N

M

N

NNN

N

N

N

N

M

R

R

OO

N

O O

N

O

O

OO

N

O O

N

O

O

O

O

N

O

O

NO O

O

O

N

O

O

NO O

N

O

O

H (6a-10)

Compound M

6, 6a 2H7 Zn8 Cu9 Co10 Ni

R: C N (6)

R:

Scheme 1. Synthesis of new polymeric phthalocyanine polymers substituted with diaza-18-crown-6 macrocycles through ethyleneoxy bridges.

A. Bilgin et al. / Polyhedron 26 (2007) 617–625 621

presence of O–H stretching vibrations at 3327 cm�1. Thedifference between the IR spectra of 1 and 3 is clear fromthe absence of characteristic vibrations such as N–H. 4-Nitrophthalonitrile (4) was treated with 3 in the presenceof Cs2CO3in DMF to afford tetranitrile monomer 5 withhigh yield (92%). Final purification of tetranitrile derivative

5 by recrystallization afforded 5 for which elemental analy-sis and EI mass spectral data were satisfactory: 602.58[M]+. In 1H NMR spectrum of 5, OH group of compound3 disappeared as expected. The disappearance of OH andthe presence of Ar–O–C at 1260 cm�1 and the presenceof C„N functional group at 2230 cm�1 in the IR spectrum

622 A. Bilgin et al. / Polyhedron 26 (2007) 617–625

of compound 5 confirm the formation of desired com-pound 5.

The metal-free phthalocyanine polymer was synthesizedby heating mixture of 5, DBU and amyl alcohol in aSchlenk tube [30]. The transition metal complexes were pre-pared from the tetracyano compound 5 and the corre-sponding metal salt in proper solvent (Scheme 1).

The molecular weights of the polymers could not bedetermined using traditional methods because of their poorsolubility in organic solvents, but by comparison of the IRabsorption bands of the end groups with those of the bridg-ing groups [15,31]. On the other hand, according to theFAB mass spectra analysis of 6 using the soluble part(�80%) of 6 in pyridine, we can say that 6 is a tetramermolecule. The 1H NMR spectrum of the soluble part ofthe 6 in pyridine-d5 displayed broad signals, and the pro-tons of the phthalocyanine core were invisible, even at ele-vated temperatures. This effect was attributed to strongaggregation of the molecules.

The IR spectra of metal-free 6, 6a and metallophthalo-cynaine polymers (7–10) are very similar. The significantdifference is the presence of m(N–H) vibrations of the innerphthalocyanine core which are assigned to a weak band at3275 cm�1 in the metal-free molecule. These bands disap-pear in the spectra of the metallophthalocyanine polymers.These bands are especially beneficial for characterization ofmetal-free phthalocyanine polymers, as there is little fre-quency dependence on ring substitution and they are notoverlapped by strong tetranitrile monomer absorptions[10]. The end groups of the metal-free phthalocyanine poly-mer were cyano groups (2223 cm�1) while the end groupsof the metallophthalocyanine polymers were imido groups(�1776–1710 cm�1). The existence of imido groups in thecase of metallophthalocyanine polymers was attributed tothe presence of the moisture during work-up and thehydrated metal salts. There was little shift to longer wave-length numbers in most of the IR bands of the metal com-plexes with respect to the metal-free analogues [10,32].

The elemental analyses of the metal-free and metallopht-halocyanine polymers (6, 6a, 7–10) were satisfactory.

The metal-free (6) and metallo polymers (7–10) gavetypical UV–Vis absorptions spectra of phthalocyanines(Table 2). As it can bee seen in Table 2 there is a shoulderat the slightly higher energy sides for all products. The

Table 2Wavelength and relative absorbance intensities of the UV–Vis spectra of the p

Compound M Solvent k/nm (Arel. · 10�1)

6 2H pyridine 706 (2.19) 672 (2.24) 640b (1.48) 606 (1.48H2SO4 810 (1.86) 720b (1.70) 675 (0.79) 608 (0.60

7 Zn H2SO4 850 (2.88) 819b (2.40) 736 (1.12) 619 (0.268 Cu H2SO4 832 (1.20) 775b (0.78) 732 (0.52) 617 (0.199 Co H2SO4 816 (1.74) 755b (0.89) 720 (0.55) 663 (0.08

10 Ni H2SO4 816 (2.51) 758b (0.79) 719 (0.52) 639 (0.33

a Intensity ratio of absorption B bands at k = 274–304 nm and Q bands at kb Shoulder.

presence of shoulders in the UV–Vis spectra of the all poly-mers corresponds to the aggregated or non-aggregated spe-cies in conc. sulfuric acid. Metal-free phthalocyaninepolymer (6) decomposes slowly by hydrolysis in conc.H2SO4, which is demonstrated by a decrease of the absorp-tion coefficient at longer wavelengths. Metal-containingpolymers (7–10), however, were stable. When going fromorganic solvents to concentrated H2SO4, the long-waveabsorption band underwent a significant bathochromicshift, which is due to degradation and weak protonationof the phthalocyanine ring at the meso nitrogen atoms.The intensity of these absorptions also decreased. TheUV–Vis spectrum of 6 was obtained in pyridine and conc.H2SO4. The electronic absorption spectrum of 6 in pyridineat room temperature is shown in Fig. 1. There were thesplit Q-band as expected and there were two strong bandsin the visible region [33]. The split Q-band which is charac-teristic for metal-free phthalocyanines observed at kmax 706and 672 nm with a shoulder at 640 nm, indicating themonomeric species; the monomeric species with D2h sym-metry shows two intense absorptions at around 700 nm[34,35]. On the other hand, such split Q-band absorptionsin pyridine are due to p) p* transition of this fully conju-gated 18p electron systems [26a]. In the case of a H2SO4

solution of 6, the primary band in the visible region wasbroadened and shifted to longer wavelength (104 nm). Inall cases the intensities in the UV (Soret band transition)and Vis (Q-band transition) were IUV/IVis 6 1 (Table 2).This result indicates the absence of poly(isoindolinine)co-units in all of the polymeric phthalocyanines (6–10).

Disaggregation of the metal-free polymeric phthalocya-nine (6), followed by changes in the visible spectra after theaddition of methanol, several alkali and NH4

þ cation, con-stitute an effective route for characterizing the complexa-tion behavior of the ethyleneoxy diaza-18-crown-6peripheral substituents. Firstly, we clarified whether meth-anol has any effect or not on the visible spectrum of 6. Forthis purpose, different amounts of methanol were added tothe solution of 6 in pyridine. As can be seen in Fig. 1decreases in the intensities of Q bands were observed inthe visible absorption spectrum of 6 with increasing theamounts of methanol. This can be due to the dilution. Thenthe different concentration of metal salts (e.g. NaNO3,KNO3, NH4NO3) solutions in methanol (1.0 · 10�3 M)

olymeric phthalocyanines

Ratioa

UV–Vis

) 389 (2.14) 360 (2.19) 320 (2.40) 301 (2.51) 285 (2.00) 0.91) 392 (1.02) 345 (2.19) 320 (2.40) 274 (2.95) 1.59

) 458 (2.24) 365 (1.95) 327 (1.51) 297 (1.38) 0.48) 430 (0.85) 412 (0.35) 338 (0.69) 304 (1.10) 0.92) 391 (2.40) 377 (1.45) 326 (2.14) 292 (2.45) 1.41) 460 (2.57) 414 (2.24) 378 (2.00) 297 (2.88) 1.14

= 719–850 nm (C = 1.0 · 10�4 g/L in H2SO4, 1.0 · 10�3 g/L in pyridine).

550 600 650 700 750 8000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

fe

d

cb

a

λ (nm)

10-3

ε /

L g-1

cm-1

a: (6) in pyridine b: a + 0.1 mL NH

4NO

3

c: a + 0.2 mL NH4NO

3

d: a + 0.3 mL NH4NO

3

e: a + 0.4 mL NH4NO

3

f : a + 0.5 mL NH4NO

3

Fig. 2. Changes in the visible spectra of 6 in pyridine (1.0 · 10�3 g/L) afterthe addition of NH4NO3 solutions in methanol (1.0 · 10�3 M).

500 550 600 650 700 750 8000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3d

c

b

a

(nm)

10-3

/ L

g-1cm

-1

a: (6) in pyridine b: a + 0.1 mL NaNO

3

c: a + 0.2 mL NaNO3

d: a + 0.3 mL NaNO3

Fig. 3. Changes in the visible spectra of 6 in pyridine (1.0 · 10�3 g/L) afterthe addition of NaNO3 solutions in methanol (1.0 · 10�3 M).

500 550 600 650 700 7500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3b

ac

de

f

λ (nm)

10-3 ε

/ L

g-1 c

m-1

a: metal-free polymer (6) in pyridineb: a + 0.1 mL methanolc: a + 0.2 mL methanol d: a + 0.3 mL methanole: a + 0.4 mL methanolf : a + 0.5 mL methanol

Fig. 1. Changes in the visible spectra of 6 in pyridine (1.0 · 10�3 g/L) afterthe addition different amounts of methanol.

A. Bilgin et al. / Polyhedron 26 (2007) 617–625 623

were added to the solution of the metal-free polymericphthalocyanine (6) in pyridine (1.0 · 10�3 g/L). When weadded NaNO3, KNO3 and NH4NO3 solutions to themetal-free polymeric phthalocyanine (6) solution caused adramatic change due to disaggregation in the visible spec-trum of 6 even in spite of dilution effect of methanol. Thisobservation can be attributed to the disaggregation of 6 bytrapped Na+, K+ and NH4

þ ions in the diaza-18-crown-6units, the radius cavity of which is harmonious with theseions and there is no intermolecular complexation betweenthe phthalocyanine units [36] (Figs. 2–4).

The intrinsic viscosities of dilute solutions of polymerswere measured by means of Ubbelohde viscometer. Theintrinsic viscosities of all polymers were similar (Table 3).Fig. 5 shows the viscosities of polymers as a function ofpolymer concentration, and indicates that viscositiesdecreased depending on polymer concentration. Thisbehavior can be explained by two effects: (1) degradationof the polymers and (2) weakly protonation of the fourbridging nitrogen atoms at the periphery of each phthalo-cyanine polymer and the nitrogen atoms of the diaza-18-crown-6 units. On the other hand, there were lineardecreasing in the case of 7 and 9 while polynomial decreas-ing in the case of 6, 8 and 10 (Fig. 5). It can be probably dueto lower stability of 6, 8 and 10 than those of others, 7 and 9.

The structure of the polymers was an Au/MPc/Au sand-wich in the configuration commonly used for the electricalconductivity measurements [37]. To prepare the samples,powdered materials were pressed at a load of 2 tons for3 min into disk-shaped compacts with a thickness of0.45–0.60 mm. The d.c. conductivity was measured by aAutolab 30 Voltammetry-FRA 2 frequency analyser. Thefrequency range was of 100 Hz–1 MHz and applied ampli-tude (rms) was 10 mV. The electrical conductivities of thepolymers were measured in a vacuum and in argon atmo-

sphere. Table 3 shows the d.c. electrical conductivities ofpolymers 6, 6a, 7–10. These values correspond to semi-con-ductive materials as encountered in number-substitutedphthalocyanine derivatives [26g]. The conductivity valuesobtained under an argon atmosphere were higher thanthose of under vacuum for all polymers probably due toabsorbed oxygen in argon [38].

The thermal stability of the phthalocyanine polymers (6–10) was determined by thermal analysis. Due to high ther-mal stability of the phthalocyanine core, cleavage of thesubstituent macrocycles takes place first and then the maindecomposition occurs above 400 �C [39]. But, the crownether units are not stable at temperatures above 300 �C evenunder inert conditions [40]. The initial decomposition tem-perature decreased in the order 7 > 9 > 10 > 8 > 6 (Table 4).

550 600 650 700 750 8000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

b

f

c

e

d

a10-3

ε /

L g-1

cm-1

λ (nm)

a: (6) in pyridine b: a + 0.1 mL KNO

3

c: a + 0.2 mL KNO3

d: a + 0.3 mL KNO3

e: a + 0.4 mL KNO3

f : a + 0.5 mL KNO3

Fig. 4. Changes in the visible spectra of 6 in pyridine (1.0 · 10�3 g/L) afterthe addition of KNO3 solutions in methanol (1.0 · 10�3 M).

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.50.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

η sp/c

c (g/dL)

Zn Co Cu Metal-free Ni

Fig. 5. Intrinsic viscosities of the polymeric phthalocyanines.

Table 3Electrical conductivity and intrinsic viscosities of the polymeric phthalo-cyanines at room temperature

Compound M Conductivity (S cm�1) Pelletthickness(mm)

Intrinsicviscosity,g (H2SO4)

In argon In vacuum

6 2H 1.12 · 10�7 9.76 · 10�8 0.55 0.756a 2H 1.83 · 10�7 1.01 · 10�7 0.457 Zn 1.05 · 10�7 7.48 · 10�8 0.60 0.678 Cu 3.06 · 10�7 6.28 · 10�7 0.45 0.899 Co 2.70 · 10�8 8.77 · 10�8 0.55 0.62

10 Ni 2.88 · 10�4 1.56 · 10�5 0.60 0.89

Table 4Thermal properties of the polymeric phthalocyanines

Compound M Initial decompositiontemperature in �C

Main decompositiontemperature in �C

6 2H 335 4757 Zn 400 6758 Cu 350 5909 Co 360 660

10 Ni 355 625

624 A. Bilgin et al. / Polyhedron 26 (2007) 617–625

Cu-containing polymer 8 was the most rapidly degradedmetallophthalocyanine while Zn-, Ni- and Co-containingmetallophthalocyanine polymers showed good thermal sta-bility under working conditions.

The alkali metal-binding ability of diaza-18-crown-6units containing polymers were evaluated. Due to theirinsolubility, heterogeneous phase extraction of alkali metal

picrates from THF solutions to the solid metal-free poly-mer was investigated. Picrate was used as counter anionfor all compounds. The results can be seen in Table 1.Examinations of the data reveal the following results: (a)the tendency of binding alkali picrates goes parallel withthe increase in the ionic diameter except for Cs+ and (b)the highest extraction affinity of 6 was determined as94.25% for K+. The extraction affinity of 6 for Li+, Na+,K+, Cs+ were determined as 6.01%, 77.17%, 94.25% and22.16%, respectively. The highest extraction affinity in thecase of K+ is probably due to the more compatibility ofK+ with macrocyclic unit than the other ions.

4. Conclusions

We have presented the synthesis and characterization ofpolymeric phthalocyanines with diaza-18-crown-6 ethyl-eneoxy bridges. The metal-free phthalocyanine polymer(6) and metallophthalocyanine polymers were preparedusing a tetranitrile monomer and proper materials. Zn-,Ni- and Co-containing polymers showed good thermal sta-bility while Cu-containing and the metal-free polymerswere the most rapidly degraded. The electrical conductivi-ties of the polymeric phthalocyanines measured as goldsandwiches were found to be 10�9–10�4 S cm�1 in vacuoand argon. The extraction ability of 6 was evaluated inTHF by using several alkali metal picrates and the highestextraction affinity was observed for K+. The intrinsic vis-cosity of the metal-free polymer and metallophthalo-cyanine polymers were similar. The metal-free polymericphthalocyanine (6) had a clear disaggregation tendencywith the addition of KNO3, NaNO3 and NH4NO3.

Acknowledgements

This study was supported by The Scientific and Techni-cal Research Council of Turkey (TUBITAK), ProjectNumber: TBAG-2453(104T065) (Ankara, Turkey). Weare also indebted to Prof. Dr. M. Hanack (University ofTubingen/Germany) and Dr. U. Kadiroglu (University ofKocaeli/Turkey) for assistance with some spectral data.

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