Optical nonlinearities and photophysicochemical behaviour of green and blue forms of lutetium bisphthalocyanines
- Sekhosana, Kutloano Edward, Amuhaya, Edith K, Mack, John, Nyokong, Tebello
- Authors: Sekhosana, Kutloano Edward , Amuhaya, Edith K , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
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- Authors: Sekhosana, Kutloano Edward , Amuhaya, Edith K , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
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Photophysicochemical properties and TD-DFT calculations of a novel terminal alkyne substituted metal free phthalocyanine
- Yilmaz, Yusuf, Mack, John, Sönmez, Mehmet, Nyokong, Tebello
- Authors: Yilmaz, Yusuf , Mack, John , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241562 , vital:50950 , xlink:href="https://doi.org/10.1142/S1088424613501241"
- Description: The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.
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- Authors: Yilmaz, Yusuf , Mack, John , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241562 , vital:50950 , xlink:href="https://doi.org/10.1142/S1088424613501241"
- Description: The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.
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Synthesis, characterization and photodynamic therapy properties of an octa-4-tert-butylphenoxy-substituted phosphorus (V) triazatetrabenzcorrole
- Shi, Maohu, Tian, Jiangwei, Mkhize, Colin, Kubheka, Gugu, Zhou, Jinfeng, Mack, John, Nyokong, Tebello, Shen, Zhen
- Authors: Shi, Maohu , Tian, Jiangwei , Mkhize, Colin , Kubheka, Gugu , Zhou, Jinfeng , Mack, John , Nyokong, Tebello , Shen, Zhen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241494 , vital:50944 , xlink:href="https://doi.org/10.1142/S1088424614500436"
- Description: A novel octa-4-tert-butylphenoxy-substituted phosphorus(V) triazatetrabenzcorrole (PVTBC), has been synthesized and characterized by MALDI-TOF MS and NMR, FT-IR and MCD spectroscopy. The fluorescence emission spectrum was used to determine the fluorescence quantum yield and the quantum yield for singlet oxygen generation was calculated by using 1,3-diphenylisobenzofuran as a scavenger. The photocytoxicity against U87MG cells was measured. The results indicated that PVTBC is potentially useful as an NIR region photosensitizer for photodynamic therapy (PDT).
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- Authors: Shi, Maohu , Tian, Jiangwei , Mkhize, Colin , Kubheka, Gugu , Zhou, Jinfeng , Mack, John , Nyokong, Tebello , Shen, Zhen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241494 , vital:50944 , xlink:href="https://doi.org/10.1142/S1088424614500436"
- Description: A novel octa-4-tert-butylphenoxy-substituted phosphorus(V) triazatetrabenzcorrole (PVTBC), has been synthesized and characterized by MALDI-TOF MS and NMR, FT-IR and MCD spectroscopy. The fluorescence emission spectrum was used to determine the fluorescence quantum yield and the quantum yield for singlet oxygen generation was calculated by using 1,3-diphenylisobenzofuran as a scavenger. The photocytoxicity against U87MG cells was measured. The results indicated that PVTBC is potentially useful as an NIR region photosensitizer for photodynamic therapy (PDT).
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Synthesis, photophysicochemical properties and TD-DFT calculations of tetrakis (2-benzoyl-4-chlorophenoxy) phthalocyanines
- Yilmaz, Yusuf, Mack, John, Sener, M Kasim, Sönmez, Mehmet, Nyokong, Tebello
- Authors: Yilmaz, Yusuf , Mack, John , Sener, M Kasim , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241538 , vital:50948 , xlink:href="https://doi.org/10.1142/S1088424614500047"
- Description: The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn(II) complex (4) was found to have a very high singlet oxygen quantum yield (ΦΔ = 0.78) in dimethylsulfoxide (DMSO) and a reasonably large triplet state quantum yield (ΦT = 0.82). The photophysical and photochemical properties clearly demonstrate that these compounds could prove useful in singlet oxygen applications such as photodynamic therapy (PDT). DFT and TD-DFT calculations were used to assess the impact of the positional isomerism of the 2-benzoyl-4-chlorophenoxy substituents on the electronic structures and optical spectroscopy.
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- Authors: Yilmaz, Yusuf , Mack, John , Sener, M Kasim , Sönmez, Mehmet , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241538 , vital:50948 , xlink:href="https://doi.org/10.1142/S1088424614500047"
- Description: The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn(II) complex (4) was found to have a very high singlet oxygen quantum yield (ΦΔ = 0.78) in dimethylsulfoxide (DMSO) and a reasonably large triplet state quantum yield (ΦT = 0.82). The photophysical and photochemical properties clearly demonstrate that these compounds could prove useful in singlet oxygen applications such as photodynamic therapy (PDT). DFT and TD-DFT calculations were used to assess the impact of the positional isomerism of the 2-benzoyl-4-chlorophenoxy substituents on the electronic structures and optical spectroscopy.
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Trends in the TD-DFT calculations of porphyrin and phthalocyanine analogs
- Mack, John, Stone, Justin, Nyokong, Tebello
- Authors: Mack, John , Stone, Justin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193882 , vital:45402 , xlink:href="https://doi.org/10.1142/S108842461450045X"
- Description: In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn (II) porphyrinoids [J. Am. Chem. Soc. 2005; 127: 17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of configurational interaction between the B and higher energy ππ* state appears to be significantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree–Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is significant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.
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- Authors: Mack, John , Stone, Justin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193882 , vital:45402 , xlink:href="https://doi.org/10.1142/S108842461450045X"
- Description: In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn (II) porphyrinoids [J. Am. Chem. Soc. 2005; 127: 17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of configurational interaction between the B and higher energy ππ* state appears to be significantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree–Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is significant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.
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