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Synthesis and photophysical properties of metal anthraquinone phthalocyanine
Chinese Chemical Letters 18 (2007) 509–512 www.elsevier.com/locate/cclet
Synthesis and photophysical properties of metal anthraquinone phthalocyanine Yi Ru Peng a,b,*, Kui Zhi Chen a,b, Jia Bao Wen a,b, Ji Cheng Shi a, Bao Quan Huang a b
a College of Chemistry & Materials Science, Fujian Normal University, Fuzhou 350007, China State Key Laboratory for Structure Chemistry, Chinese Academy of Science, Fuzhou 350003, China
Received 16 October 2006
Abstract A novel anthraquinone phthalocyanine Al(III) 4 and Co(II) 5 were synthesized and characterized by elemental analysis, IR, UV/ vis, 1H NMR, HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by fluorescence spectrum method. # 2007 Yi Ru Peng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Anthraquinone phthalocyanine Al(III) and Co(II); Synthesis; Characterization; Photophysical properties
Phthalocyanine (Pc) and their substituted derivatives had aroused extensive interest in the last decade, as they were widely used as photosensitizers in photodynamic therapy (PDT) of cancer or macular degeneration [1]. These Pcs showed high molar extinction coefficients in the 600–800 nm region and were capable of generating singlet oxygen, which was the reactive species, believed to be the main responsible of the cytotoxic effect in the photodynamic process. Most Pcs were tetra substituted, however these tetra substitution induced tedious work in separation and characterization due to the region-isomers. We herein reported the synthesis of a new type of anthraquinone phthalocyanine Al(III) 4 and Co(II) 5. We are particularly interested in this compound, because of its easy preparation, unique isomer and red-shift wavelength. Besides, the photophysical properties of the two metal complexes were compared and studied. The synthetic route for compounds 4 and 5 was shown in Scheme 1. (3,4-Dimethy-benzoyl)benzoic acid 1 and 2,3dimethylanthraquinone 2 were synthesized according to literature [2] with little modification. 2 reacted with potassium permangante in concentrated sulfuric acid to give anthraquinone-2,3-dicarboxylic acid 3. 3 was further purified by silica gel chromatography (CH2Cl2/methanol, 9:1), and recrystallized from methanol to afford light yellow crystals. They were characterized by IR, 1H NMR and elemental analysis [3]. 3 was condensed using ammonium molybdate as catalyst and anhydrous metal chloride as template to give crude product 4 or 5. The blue crude product was purified by silica gel chromatography (acetone), and recrystallized from acetone to afford light blue crystals 4 or 5 in 45% and 34% yield, respectively.
* Corresponding author at: College of Chemistry & Materials Science, Fujian Normal University, Fuzhou 350007, China. E-mail address: [email protected] (Y.R. Peng). 1001-8417/$ – see front matter # 2007 Yi Ru Peng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.03.004
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Scheme 1. Conditions: (a) KMnO4 and (b) (MH4)2MoO4. 4. M = Al; 5. M = Co.
The structure of 4 and 5 were confirmed by UV/vis, IR, 1H NMR, elemental analysis, HPLC and MS. The molecular formula of 4 was AlC48H40N8O8: calculated (%): C, 66.74; H, 4.63; N, 12.98; found (%): C, 66.12; H, 5.13; N, 12.44. The molecular formula of 5 was CoC48H40N8O8: calculated (%): C, 64.50; H, 4.48; N, 12.54; found (%): C, 65.31; H, 4.98; N, 12.56. MS for 4 m/z: 882(M+) and for 5 m/z: 914(M+). The purity of two compounds was analyzed by HPLC. There was only one peak with retention time at 2.73 and 2.89 min, respectively, for 4 or 5, which indicated that they existed as a singer isomer. The 1H NMR spectrum of 4 or 5 in DMSO-d6 showed only the aromatic proton signals. The more deshielded signals at d 8.012 or 8.013 contributed to the protons on anthraquinone groups of 4 or 5, respectively, while the least deshielded signals at d 6.958 or 6.959 belonged to the protons on the Pc ring of 4 or 5, respectively. It indicated that there was only one type of magnetically equivalent isoindoline unites in the Pc ring, suggesting that the structures 4 and 5 might be C 4v or D2h. The electronic spectra of the two compounds showed only one characteristic Q peak (Fig. 1), suggesting they were C 4v isomer [4]. In the electronic spectra (Fig. 1), 4 showed typical non-aggregated Pc with an intense and sharp Q band at 684 nm, while 5 showed a relatively broadened Q band at 679 nm in DMF. It might be supposed, that the ligand coordinated with Al was axial in 4, preventing the aggregation of the Pc ring. When increased the concentration of 4 and 5, 4 still exhibited the narrowed Q band at 684 nm, while 5 showed the increase of intensity of dimmer at 620 nm and decrease of the intensity of monomer at 679 nm. The fluorescence emission spectra, fluorescence decay and fitted curves, and photophysical data (S1) of 4 and 5 were shown in Figs. 2 and 3 and Table 1. The following results were showed: (1) compared with non-substituted metal Pc, the fluorescence emission wavelengths of 4 and 5 with anthraquinone
Fig. 1. Electronic spectra of 4 and 5 in DMF. (a) 4 and (b) 5.
Y.R. Peng et al. / Chinese Chemical Letters 18 (2007) 509–512
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Fig. 2. Fluorescence emission spectra of 4 and 5 in DMF. (a) 4 and (b) 5.
Fig. 3. Fluorescence decay and fitted curves of 4 and 5 in DMF. (a) 4 and (b) 5. Table 1 Photophysical data (S1) of 4 and 5a K (s1)
Compound
lab max (nm)
lcm max (nm)
FF a
ts (ns)
Ea (kJ/mol)
1
4 5
684 679
699 680
0.40 0.05
4.25 0.43
172.5 171.5
3.45 10 8 1.02 10 8
a
Relative to ZnPc (FF = 0.30 in 1-chloronaphthalene).
substitutions were red shift by 10 nm. It might be due to the introduction of the substituent groups, enlarging the conjugated system of Pc and decreasing the energy gap between the HOMO and LUMO. (2) The central metal ion exerted obviously effect on the fluorescence quantum yield (FF) and fluorescence lifetime (ts) [5]. 4 with paramagnetic aluminum ion showed longer FF of 0.40 and ts of 4.25 ns, 5 with anti-paramagnetic cobalt ion, whose FF was 0.05 and ts was 0.43 ns. (3) The central metal ion also had obviously effect on the intensity of fluorescence emission. 4 with paramagnetic aluminum ion showed a stronger fluorescence emission at 699 nm, 5 with antiparamagnetic cobalt ion, whose fluorescence emission was at 680 nm. In summary, 4 and 5 were synthesized and characterized as C 4v isomer. Their photophysical properties were compared and studied. As 4 had stronger fluorescence emission and higher fluorescence quantum yield and longer fluorescence lifetime, it has potential application for PDT as photosensitizer. Acknowledgments This study was supported by the National Natural Science Foundation of China (No. 20604007), Natural Science Foundation of Fujian (No. C0510007), Key Foundation for Ministry of Education (No. 206071), Key Foundation for Education Office of Fujian (No. JA05195), and Key Laboratory for Structure Chemistry (No. 040083). References [1] Z. Huang, Technol. Cancer Res. Treat. 4 (2005) 283. [2] (a) A. Fairboune, J. Am. Chem. Soc. 119 (1921) 1573; (b) K. Tanaka, T. Miura, N. Umezawa, et al. J. Am. Chem. Soc. 123 (2001) 2530.
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Y.R. Peng et al. / Chinese Chemical Letters 18 (2007) 509–512
[3] Analytical data for 1, yellow powder (4.78 g, yield 37%). Mp: 170.6 8C. IR (KBr, cm1): 3450, 2900, 1770. 1690, 1600, 1400, 1225, 1100, 900, 710. 1H NMR (DMSO-d6, d ppm): 2.23 (s, 3H), 7.22–7.30 (m, 2H), 7.35 (d, 1H, J = 7.3 Hz), 7.46 (s, 1H), 7.72–7.30 (m, 2H), 7.96 (d, 1H, J = 7.3 Hz). C16H14O3: calculated (%): C, 75.59, H, 5.55, found (%): C, 75.03; H, 5.50. Analytical data for 2, yellow needles (2.0 g, 46%). Mp: 185 8C. 1H NMR (CDCl3, d ppm): 2.25 (s, 6H), 7.76–7.79 (m, 2H), 8.06 (s, 2H), 8.28–8.31 (m, 2H); IR (KBr, cm1): 900, 2600, 1675, 1420, 1300, 780, 710; C16H14O3: calculated (%): C, 81.33, H, 5.12, found (%): C, 80.57; H, 5.04. Analytical data for 3, 1H NMR (DMSO-d6, d ppm): d 7.97–8.00 (m, 2H), 8.31–8.34 (m, 2H), 8.58 (s, 2H). C16H8O6: calculated (%): C, 64.78; H, 2.72, found (%): C, 64.13; H, 2.59. [4] J.L. Huang, Y.R. Peng, N.S. Chen, Chin. J. Struct. 20 (2001) 144. [5] The fluorescence lifetimes (ts) were obtained from the decay of transient fluorescence spectra using a picosecond dye laser with an excited wavelength at 350 nm. The data was processed by computer settling the fitted exponential equation: Fit ¼ A þ B1 et=t þ B2 et=t þ B3 et=t þ B4 et=t .
Synthesis and photophysical properties of metal anthraquinone phthalocyanine Yi Ru Peng a,b,*, Kui Zhi Chen a,b, Jia Bao Wen a,b, Ji Cheng Shi a, Bao Quan Huang a b
a College of Chemistry & Materials Science, Fujian Normal University, Fuzhou 350007, China State Key Laboratory for Structure Chemistry, Chinese Academy of Science, Fuzhou 350003, China
Received 16 October 2006
Abstract A novel anthraquinone phthalocyanine Al(III) 4 and Co(II) 5 were synthesized and characterized by elemental analysis, IR, UV/ vis, 1H NMR, HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by fluorescence spectrum method. # 2007 Yi Ru Peng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Anthraquinone phthalocyanine Al(III) and Co(II); Synthesis; Characterization; Photophysical properties
Phthalocyanine (Pc) and their substituted derivatives had aroused extensive interest in the last decade, as they were widely used as photosensitizers in photodynamic therapy (PDT) of cancer or macular degeneration [1]. These Pcs showed high molar extinction coefficients in the 600–800 nm region and were capable of generating singlet oxygen, which was the reactive species, believed to be the main responsible of the cytotoxic effect in the photodynamic process. Most Pcs were tetra substituted, however these tetra substitution induced tedious work in separation and characterization due to the region-isomers. We herein reported the synthesis of a new type of anthraquinone phthalocyanine Al(III) 4 and Co(II) 5. We are particularly interested in this compound, because of its easy preparation, unique isomer and red-shift wavelength. Besides, the photophysical properties of the two metal complexes were compared and studied. The synthetic route for compounds 4 and 5 was shown in Scheme 1. (3,4-Dimethy-benzoyl)benzoic acid 1 and 2,3dimethylanthraquinone 2 were synthesized according to literature [2] with little modification. 2 reacted with potassium permangante in concentrated sulfuric acid to give anthraquinone-2,3-dicarboxylic acid 3. 3 was further purified by silica gel chromatography (CH2Cl2/methanol, 9:1), and recrystallized from methanol to afford light yellow crystals. They were characterized by IR, 1H NMR and elemental analysis [3]. 3 was condensed using ammonium molybdate as catalyst and anhydrous metal chloride as template to give crude product 4 or 5. The blue crude product was purified by silica gel chromatography (acetone), and recrystallized from acetone to afford light blue crystals 4 or 5 in 45% and 34% yield, respectively.
* Corresponding author at: College of Chemistry & Materials Science, Fujian Normal University, Fuzhou 350007, China. E-mail address: [email protected] (Y.R. Peng). 1001-8417/$ – see front matter # 2007 Yi Ru Peng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.03.004
510
Y.R. Peng et al. / Chinese Chemical Letters 18 (2007) 509–512
Scheme 1. Conditions: (a) KMnO4 and (b) (MH4)2MoO4. 4. M = Al; 5. M = Co.
The structure of 4 and 5 were confirmed by UV/vis, IR, 1H NMR, elemental analysis, HPLC and MS. The molecular formula of 4 was AlC48H40N8O8: calculated (%): C, 66.74; H, 4.63; N, 12.98; found (%): C, 66.12; H, 5.13; N, 12.44. The molecular formula of 5 was CoC48H40N8O8: calculated (%): C, 64.50; H, 4.48; N, 12.54; found (%): C, 65.31; H, 4.98; N, 12.56. MS for 4 m/z: 882(M+) and for 5 m/z: 914(M+). The purity of two compounds was analyzed by HPLC. There was only one peak with retention time at 2.73 and 2.89 min, respectively, for 4 or 5, which indicated that they existed as a singer isomer. The 1H NMR spectrum of 4 or 5 in DMSO-d6 showed only the aromatic proton signals. The more deshielded signals at d 8.012 or 8.013 contributed to the protons on anthraquinone groups of 4 or 5, respectively, while the least deshielded signals at d 6.958 or 6.959 belonged to the protons on the Pc ring of 4 or 5, respectively. It indicated that there was only one type of magnetically equivalent isoindoline unites in the Pc ring, suggesting that the structures 4 and 5 might be C 4v or D2h. The electronic spectra of the two compounds showed only one characteristic Q peak (Fig. 1), suggesting they were C 4v isomer [4]. In the electronic spectra (Fig. 1), 4 showed typical non-aggregated Pc with an intense and sharp Q band at 684 nm, while 5 showed a relatively broadened Q band at 679 nm in DMF. It might be supposed, that the ligand coordinated with Al was axial in 4, preventing the aggregation of the Pc ring. When increased the concentration of 4 and 5, 4 still exhibited the narrowed Q band at 684 nm, while 5 showed the increase of intensity of dimmer at 620 nm and decrease of the intensity of monomer at 679 nm. The fluorescence emission spectra, fluorescence decay and fitted curves, and photophysical data (S1) of 4 and 5 were shown in Figs. 2 and 3 and Table 1. The following results were showed: (1) compared with non-substituted metal Pc, the fluorescence emission wavelengths of 4 and 5 with anthraquinone
Fig. 1. Electronic spectra of 4 and 5 in DMF. (a) 4 and (b) 5.
Y.R. Peng et al. / Chinese Chemical Letters 18 (2007) 509–512
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Fig. 2. Fluorescence emission spectra of 4 and 5 in DMF. (a) 4 and (b) 5.
Fig. 3. Fluorescence decay and fitted curves of 4 and 5 in DMF. (a) 4 and (b) 5. Table 1 Photophysical data (S1) of 4 and 5a K (s1)
Compound
lab max (nm)
lcm max (nm)
FF a
ts (ns)
Ea (kJ/mol)
1
4 5
684 679
699 680
0.40 0.05
4.25 0.43
172.5 171.5
3.45 10 8 1.02 10 8
a
Relative to ZnPc (FF = 0.30 in 1-chloronaphthalene).
substitutions were red shift by 10 nm. It might be due to the introduction of the substituent groups, enlarging the conjugated system of Pc and decreasing the energy gap between the HOMO and LUMO. (2) The central metal ion exerted obviously effect on the fluorescence quantum yield (FF) and fluorescence lifetime (ts) [5]. 4 with paramagnetic aluminum ion showed longer FF of 0.40 and ts of 4.25 ns, 5 with anti-paramagnetic cobalt ion, whose FF was 0.05 and ts was 0.43 ns. (3) The central metal ion also had obviously effect on the intensity of fluorescence emission. 4 with paramagnetic aluminum ion showed a stronger fluorescence emission at 699 nm, 5 with antiparamagnetic cobalt ion, whose fluorescence emission was at 680 nm. In summary, 4 and 5 were synthesized and characterized as C 4v isomer. Their photophysical properties were compared and studied. As 4 had stronger fluorescence emission and higher fluorescence quantum yield and longer fluorescence lifetime, it has potential application for PDT as photosensitizer. Acknowledgments This study was supported by the National Natural Science Foundation of China (No. 20604007), Natural Science Foundation of Fujian (No. C0510007), Key Foundation for Ministry of Education (No. 206071), Key Foundation for Education Office of Fujian (No. JA05195), and Key Laboratory for Structure Chemistry (No. 040083). References [1] Z. Huang, Technol. Cancer Res. Treat. 4 (2005) 283. [2] (a) A. Fairboune, J. Am. Chem. Soc. 119 (1921) 1573; (b) K. Tanaka, T. Miura, N. Umezawa, et al. J. Am. Chem. Soc. 123 (2001) 2530.
512
Y.R. Peng et al. / Chinese Chemical Letters 18 (2007) 509–512
[3] Analytical data for 1, yellow powder (4.78 g, yield 37%). Mp: 170.6 8C. IR (KBr, cm1): 3450, 2900, 1770. 1690, 1600, 1400, 1225, 1100, 900, 710. 1H NMR (DMSO-d6, d ppm): 2.23 (s, 3H), 7.22–7.30 (m, 2H), 7.35 (d, 1H, J = 7.3 Hz), 7.46 (s, 1H), 7.72–7.30 (m, 2H), 7.96 (d, 1H, J = 7.3 Hz). C16H14O3: calculated (%): C, 75.59, H, 5.55, found (%): C, 75.03; H, 5.50. Analytical data for 2, yellow needles (2.0 g, 46%). Mp: 185 8C. 1H NMR (CDCl3, d ppm): 2.25 (s, 6H), 7.76–7.79 (m, 2H), 8.06 (s, 2H), 8.28–8.31 (m, 2H); IR (KBr, cm1): 900, 2600, 1675, 1420, 1300, 780, 710; C16H14O3: calculated (%): C, 81.33, H, 5.12, found (%): C, 80.57; H, 5.04. Analytical data for 3, 1H NMR (DMSO-d6, d ppm): d 7.97–8.00 (m, 2H), 8.31–8.34 (m, 2H), 8.58 (s, 2H). C16H8O6: calculated (%): C, 64.78; H, 2.72, found (%): C, 64.13; H, 2.59. [4] J.L. Huang, Y.R. Peng, N.S. Chen, Chin. J. Struct. 20 (2001) 144. [5] The fluorescence lifetimes (ts) were obtained from the decay of transient fluorescence spectra using a picosecond dye laser with an excited wavelength at 350 nm. The data was processed by computer settling the fitted exponential equation: Fit ¼ A þ B1 et=t þ B2 et=t þ B3 et=t þ B4 et=t .