Synthesis and photophysical studies of asymmetric zinc phthalocyanine–magnetic nanoparticle conjugates
- Matlou, Gauta G, Kobayashi, Nagao, Kimura, Mutsumi, Nyokong, Tebello
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232895 , vital:50036 , xlink:href="https://doi.org/10.1039/C7NJ01716B"
- Description: This work reports on the synthesis and amide bond linkage of carboxylic acid functionalized asymmetric zinc phthalocyanine (ZnPc) complexes to amino magnetic nanoparticles (AMNPs). The work further compares the photophysical and photochemical parameters of the Pc complexes alone with those linked to form ZnPc–AMNPs with further relation to the type of the spacer between the Pc and the AMNPs. Infrared spectroscopy confirmed the presence of the amide bond formed between the Pc complexes and the AMNPs. The triplet quantum yields ranged from 0.62 to 0.87. However, low singlet oxygen quantum yields were obtained due to competing pathways and the insufficient energy transfer from the excited triplet state of the ZnPc molecules to the molecular oxygen.
- Full Text:
- Date Issued: 2017
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232895 , vital:50036 , xlink:href="https://doi.org/10.1039/C7NJ01716B"
- Description: This work reports on the synthesis and amide bond linkage of carboxylic acid functionalized asymmetric zinc phthalocyanine (ZnPc) complexes to amino magnetic nanoparticles (AMNPs). The work further compares the photophysical and photochemical parameters of the Pc complexes alone with those linked to form ZnPc–AMNPs with further relation to the type of the spacer between the Pc and the AMNPs. Infrared spectroscopy confirmed the presence of the amide bond formed between the Pc complexes and the AMNPs. The triplet quantum yields ranged from 0.62 to 0.87. However, low singlet oxygen quantum yields were obtained due to competing pathways and the insufficient energy transfer from the excited triplet state of the ZnPc molecules to the molecular oxygen.
- Full Text:
- Date Issued: 2017
Aggregation control of robust water-soluble zinc (II) phthalocyanine-based photosensitizers
- Ikeuchi, Takuro, Mack, John, Nyokong, Tebello, Kobayashi, Nagao, Kimura, Mutsumi
- Authors: Ikeuchi, Takuro , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Kimura, Mutsumi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239709 , vital:50757 , xlink:href="https://doi.org/10.1021/acs.langmuir.6b03552"
- Description: A water-soluble zinc phthalocyanine (ZnPc) complex with four negatively charged electron-withdrawing sulfonic acid substituents at the nonperipheral positions (α-ZnTSPc) is found to have a high singlet oxygen (1O2) quantum yield and exhibits high photostability. The formation of aggregates is hindered and the highest occupied molecular orbital is significantly stabilized, making α-ZnTSPc potentially suitable for its use as a photosensitizer for photodynamic therapy and photoimmunotherapy. Atomic force microscopy (AFM) reveals that mixtures of the negatively charged α-ZnTSPc complex with a similar positively charged ZnPc were found to result in the self-assembly of one-dimensional accordion-like fibers. Supramolecular fibers can be formed in aqueous solutions through intermolecular electrostatic and donor–acceptor interactions between the two water-soluble ZnPcs.
- Full Text:
- Date Issued: 2016
- Authors: Ikeuchi, Takuro , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Kimura, Mutsumi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239709 , vital:50757 , xlink:href="https://doi.org/10.1021/acs.langmuir.6b03552"
- Description: A water-soluble zinc phthalocyanine (ZnPc) complex with four negatively charged electron-withdrawing sulfonic acid substituents at the nonperipheral positions (α-ZnTSPc) is found to have a high singlet oxygen (1O2) quantum yield and exhibits high photostability. The formation of aggregates is hindered and the highest occupied molecular orbital is significantly stabilized, making α-ZnTSPc potentially suitable for its use as a photosensitizer for photodynamic therapy and photoimmunotherapy. Atomic force microscopy (AFM) reveals that mixtures of the negatively charged α-ZnTSPc complex with a similar positively charged ZnPc were found to result in the self-assembly of one-dimensional accordion-like fibers. Supramolecular fibers can be formed in aqueous solutions through intermolecular electrostatic and donor–acceptor interactions between the two water-soluble ZnPcs.
- Full Text:
- Date Issued: 2016
Organosilicon compounds as fluorescent chemosensors for fluoride anion recognition
- Gai, Lizhi, Mack, John, Lu, Hua, Nyokong, Tebello, Li, Zhifang, Kobayashi, Nagao, Shen, Zhen
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- Full Text:
- Date Issued: 2015
- Authors: Gai, Lizhi , Mack, John , Lu, Hua , Nyokong, Tebello , Li, Zhifang , Kobayashi, Nagao , Shen, Zhen
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241424 , vital:50938 , xlink:href="https://doi.org/10.1016/j.ccr.2014.10.009"
- Description: Recent developments in organosilicon-based chemosensors for F− recognition are reviewed. The design strategies for improving the photophysical properties of organosilicon-based chemosensors are elaborated, with an emphasis placed on their utility for biological applications. The photophysical properties and electronic structures are analyzed in depth with reference made to the results of molecular modeling calculation and possible future research directions are assessed.
- Full Text:
- Date Issued: 2015
MCD spectroscopy and TD-DFT calculations of a naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer
- Mack, John, Liang, Xu, Dubinina, Tatiana V, Tomilova, Larisa G, Nyokong, Tebello, Kobayashi, Nagao
- Authors: Mack, John , Liang, Xu , Dubinina, Tatiana V , Tomilova, Larisa G , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232511 , vital:49998 , xlink:href="https://doi.org/10.1142/S1088424613500259"
- Description: Magnetic circular dichroism (MCD) spectroscopy and TD-DFT calculations are used to analyze the electronic structure and optical properties of an alkyl-substituted naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer. An analysis of the MCD spectrum of the naphthalene-ring-bridged dimer relative to those of benzene-bridged compounds reported previously, demonstrates that there is a significantly weaker interaction between the two phthalocyanine rings. TD-DFT results obtained using the B3LYP functional with 6–31G basis sets were found to be problematic. Closer agreement with the experimental data is obtained when the CAM-B3LYP functional is used instead. The naphthalene-ring-bridged compound is found to be unsuitable for use as a photosensitizer for the formation of singlet oxygen, because the ΦT values are negligible.
- Full Text:
- Date Issued: 2013
- Authors: Mack, John , Liang, Xu , Dubinina, Tatiana V , Tomilova, Larisa G , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232511 , vital:49998 , xlink:href="https://doi.org/10.1142/S1088424613500259"
- Description: Magnetic circular dichroism (MCD) spectroscopy and TD-DFT calculations are used to analyze the electronic structure and optical properties of an alkyl-substituted naphthalene-ring-bridged coplanar binuclear phthalocyanine dimer. An analysis of the MCD spectrum of the naphthalene-ring-bridged dimer relative to those of benzene-bridged compounds reported previously, demonstrates that there is a significantly weaker interaction between the two phthalocyanine rings. TD-DFT results obtained using the B3LYP functional with 6–31G basis sets were found to be problematic. Closer agreement with the experimental data is obtained when the CAM-B3LYP functional is used instead. The naphthalene-ring-bridged compound is found to be unsuitable for use as a photosensitizer for the formation of singlet oxygen, because the ΦT values are negligible.
- Full Text:
- Date Issued: 2013
Flexible Metal–Porphyrin Dimers (M= MnIIICl, CoII, NiII, CuII)
- Li, Minzhi, Zhang, Qian, Xu, Li, Zhu, Weihua, Mack, John, May, Aviwe K, Nyokong, Tebello, Kobayashi, Nagao, Liang, Xu
- Authors: Li, Minzhi , Zhang, Qian , Xu, Li , Zhu, Weihua , Mack, John , May, Aviwe K , Nyokong, Tebello , Kobayashi, Nagao , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239676 , vital:50754 , xlink:href="https://doi.org/10.1002/cplu.201600475"
- Description: Four metalloporphyrin dimers linked by bridging amide-bonded xanthene moieties and that contain either MnIII, CoII, NiII, or CuII metal centers were synthesized. Various spectroscopic, electrochemical, and spectroelectrochemical methods were used to study trends in their properties. Their electronic structure and optical properties were analyzed through a comparison of the electronic absorption and magnetic circular dichroism (MCD) spectral data with the results of time-dependent (TD)-DFT calculations.
- Full Text:
- Date Issued: 2017
- Authors: Li, Minzhi , Zhang, Qian , Xu, Li , Zhu, Weihua , Mack, John , May, Aviwe K , Nyokong, Tebello , Kobayashi, Nagao , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239676 , vital:50754 , xlink:href="https://doi.org/10.1002/cplu.201600475"
- Description: Four metalloporphyrin dimers linked by bridging amide-bonded xanthene moieties and that contain either MnIII, CoII, NiII, or CuII metal centers were synthesized. Various spectroscopic, electrochemical, and spectroelectrochemical methods were used to study trends in their properties. Their electronic structure and optical properties were analyzed through a comparison of the electronic absorption and magnetic circular dichroism (MCD) spectral data with the results of time-dependent (TD)-DFT calculations.
- Full Text:
- Date Issued: 2017
Trends in the optical and redox properties of tetraphenyltetraphenanthroporphyrins
- Mack, John, Lobb, Kevin, Nyokong, Tebello, Shen, Zhen, Kobayashi, Nagao
- Authors: Mack, John , Lobb, Kevin , Nyokong, Tebello , Shen, Zhen , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245809 , vital:51407 , xlink:href="https://doi.org/10.1142/S1088424612500885"
- Description: The results of TD-DFT calculations for a series of tetraaryltetraphenanthroporphyrins containing para-substituents with differing electron donating and accepting properties are compared to the observed optical and redox properties and Michl's perimeter model is used as a conceptual framework for analyzing the results.
- Full Text:
- Date Issued: 2012
- Authors: Mack, John , Lobb, Kevin , Nyokong, Tebello , Shen, Zhen , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245809 , vital:51407 , xlink:href="https://doi.org/10.1142/S1088424612500885"
- Description: The results of TD-DFT calculations for a series of tetraaryltetraphenanthroporphyrins containing para-substituents with differing electron donating and accepting properties are compared to the observed optical and redox properties and Michl's perimeter model is used as a conceptual framework for analyzing the results.
- Full Text:
- Date Issued: 2012
Comparative Spectroscopic and Electrochemical Properties of Bis (octakis (dodecylthio) naphthalocyaninato) europium (III) and Bis (tetra-tert-butylnaphthalocyaninato) europium (III) Complexes
- Nyokong, Tebello, Furuya, Fumio, Kobayashi, Nagao, Du, Daming, Liu, Wei, Jiang, Jianzhuang
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000
Optical limiting properties of 2, 6-dibromo-3, 5-distyrylBODIPY dyes at 532 nm
- Kubheka, Gugu, Mack, John, Kobayashi, Nagao, Kimura, Mitsumi, Nyokong, Tebello
- Authors: Kubheka, Gugu , Mack, John , Kobayashi, Nagao , Kimura, Mitsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190405 , vital:44991 , xlink:href="https://doi.org/10.1142/S1088424617500511"
- Description: Optical limiting properties of 2,6-dibromo-3,5-distyrylBODIPY dyes were investigated by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed even in solution, which suggests that compounds of this type are potentially suitable for use in optical limiting applications.
- Full Text:
- Date Issued: 2017
- Authors: Kubheka, Gugu , Mack, John , Kobayashi, Nagao , Kimura, Mitsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190405 , vital:44991 , xlink:href="https://doi.org/10.1142/S1088424617500511"
- Description: Optical limiting properties of 2,6-dibromo-3,5-distyrylBODIPY dyes were investigated by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed even in solution, which suggests that compounds of this type are potentially suitable for use in optical limiting applications.
- Full Text:
- Date Issued: 2017
Photodynamic activity of 2, 6-dibrominated dimethylaminophenylbuta-1, 3-dienylBODIPY dyes
- Khubeka, Gugu, Babu, Balaji, Prinsloo, Earl, Kobayashi, Nagao, Mack, John, Nyokong, Tebello
- Authors: Khubeka, Gugu , Babu, Balaji , Prinsloo, Earl , Kobayashi, Nagao , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190804 , vital:45030 , xlink:href="https://doi.org/10.1142/S1088424620500509"
- Description: Mono- and disubstituted 2,6-dibromo-dimethylaminophenylbuta-1,3-dienylBODIPY dyes were successfully prepared, and their in vitro photodynamic activities against MCF-7 breast cancer cells were evaluated with a Thorlabs M660L4 660 nm LED (336 J · cm−2)−2). The IC5050 value of the monophenylbuta-1,3-dienylBODIPY was ca. 2.1 μμM, while that of the diphenylbuta-1,3-dienylBODIPY was > 50 μμM. Both dyes exhibited minimal dark toxicity. The results demonstrate that monosubstituted 2,6-dibromo-dimethylaminophenylbuta-1,3-dienylBODIPY dyes merit further in-depth study for use as photosensitizer dyes in photodynamic therapy.
- Full Text:
- Date Issued: 2021
- Authors: Khubeka, Gugu , Babu, Balaji , Prinsloo, Earl , Kobayashi, Nagao , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190804 , vital:45030 , xlink:href="https://doi.org/10.1142/S1088424620500509"
- Description: Mono- and disubstituted 2,6-dibromo-dimethylaminophenylbuta-1,3-dienylBODIPY dyes were successfully prepared, and their in vitro photodynamic activities against MCF-7 breast cancer cells were evaluated with a Thorlabs M660L4 660 nm LED (336 J · cm−2)−2). The IC5050 value of the monophenylbuta-1,3-dienylBODIPY was ca. 2.1 μμM, while that of the diphenylbuta-1,3-dienylBODIPY was > 50 μμM. Both dyes exhibited minimal dark toxicity. The results demonstrate that monosubstituted 2,6-dibromo-dimethylaminophenylbuta-1,3-dienylBODIPY dyes merit further in-depth study for use as photosensitizer dyes in photodynamic therapy.
- Full Text:
- Date Issued: 2021
Synthesis, Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems
- Okujima, Tetsuo, Mack, John, Nakamura, Jun, Kubheka, Gugu, Nyokong, Tebello, Zhu, Hua, Komobuchi, Naoki, Ono, Noboru, Yamada, Hiroko, Uno, Hidemitsu, Kobayashi, Nagao
- Authors: Okujima, Tetsuo , Mack, John , Nakamura, Jun , Kubheka, Gugu , Nyokong, Tebello , Zhu, Hua , Komobuchi, Naoki , Ono, Noboru , Yamada, Hiroko , Uno, Hidemitsu , Kobayashi, Nagao
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240360 , vital:50827 , xlink:href="https://doi.org/10.1002/chem.201602213"
- Description: A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro-Diels–Alder reaction of bicyclo[2.2.2]octadiene-fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time-dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π-molecular orbitals.
- Full Text:
- Date Issued: 2016
- Authors: Okujima, Tetsuo , Mack, John , Nakamura, Jun , Kubheka, Gugu , Nyokong, Tebello , Zhu, Hua , Komobuchi, Naoki , Ono, Noboru , Yamada, Hiroko , Uno, Hidemitsu , Kobayashi, Nagao
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240360 , vital:50827 , xlink:href="https://doi.org/10.1002/chem.201602213"
- Description: A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro-Diels–Alder reaction of bicyclo[2.2.2]octadiene-fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time-dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π-molecular orbitals.
- Full Text:
- Date Issued: 2016
Physicochemical and photodynamic antimicrobial chemotherapy activity of morpholine-substituted phthalocyanines: Effect of point of substitution and central metal
- Sindelo, Azole, Kobayashi, Nagao, Kimura, Mutsumi, Nyokong, Tebello
- Authors: Sindelo, Azole , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187438 , vital:44652 , xlink:href="https://doi.org/10.1016/j.jphotochem.2019.01.025"
- Description: In this study, novel metal-free, zinc and indium 1(4),8(11),15(18),22(25)-tetramorpholine (1a, 2a, 3a respectively) and 2(3), 9(10), 16(17),23(24)-tetramorpholine (1b, 2b, 3b respectively) phthalocyanines were synthesized and complexes 2 and 3 were quaternized. The photophysical and photochemical properties were investigated in dimethylsulfoxide. The non-peripherally substituted phthalocyanines generated higher singlet oxygen than the peripherally substituted phthalocyanines. Photodynamic antimicrobial chemotherapy activities towards inactivation of Escherichia coli, Staphylococcus aureus and Candida albican were evaluated, where all the quaternized Pcs showed total elimination of the micro-organism with log reductions greater than 9. Though the neutral Pcs had log reductions less than 2, for C. albican the percentage reduction was 68.5% for 2b showing the antifungal properties of the morpholine group.
- Full Text:
- Date Issued: 2019
- Authors: Sindelo, Azole , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187438 , vital:44652 , xlink:href="https://doi.org/10.1016/j.jphotochem.2019.01.025"
- Description: In this study, novel metal-free, zinc and indium 1(4),8(11),15(18),22(25)-tetramorpholine (1a, 2a, 3a respectively) and 2(3), 9(10), 16(17),23(24)-tetramorpholine (1b, 2b, 3b respectively) phthalocyanines were synthesized and complexes 2 and 3 were quaternized. The photophysical and photochemical properties were investigated in dimethylsulfoxide. The non-peripherally substituted phthalocyanines generated higher singlet oxygen than the peripherally substituted phthalocyanines. Photodynamic antimicrobial chemotherapy activities towards inactivation of Escherichia coli, Staphylococcus aureus and Candida albican were evaluated, where all the quaternized Pcs showed total elimination of the micro-organism with log reductions greater than 9. Though the neutral Pcs had log reductions less than 2, for C. albican the percentage reduction was 68.5% for 2b showing the antifungal properties of the morpholine group.
- Full Text:
- Date Issued: 2019
Optically active BODIPYs
- Lu, Hua, Mack, John, Nyokong, Tebello, Kobayashi, Nagao, Shen, Zhen
- Authors: Lu, Hua , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240421 , vital:50833 , xlink:href="https://doi.org/10.1016/j.ccr.2016.03.015"
- Description: This review highlights and summarizes various optically active BODIPY molecules and describes the analysis of their circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy, to provide a platform for the rational design of novel optically active BODIPY structures and the development of new chiroptical applications. Possible future research directions are also discussed.
- Full Text:
- Date Issued: 2016
- Authors: Lu, Hua , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240421 , vital:50833 , xlink:href="https://doi.org/10.1016/j.ccr.2016.03.015"
- Description: This review highlights and summarizes various optically active BODIPY molecules and describes the analysis of their circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy, to provide a platform for the rational design of novel optically active BODIPY structures and the development of new chiroptical applications. Possible future research directions are also discussed.
- Full Text:
- Date Issued: 2016
Electrocatalytic behavior of cobalt phthalocyanine complexes immobilized on glassy carbon electrode towards the reduction of dicrotophos pesticide
- Vilakazi, Sibulelo, Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245832 , vital:51409 , xlink:href="https://doi.org/10.1142/S1088424612501040"
- Description: Electrocatalytic properties of cobalt phthalocyanine (CoPc), cobalt tetra-carboxy phthalocyanine (CoTCPc) and cobalt octa-carboxy (CoOCPc), towards the detection of dicrotophos have been studied. Catalytic behavior towards the reduction of dicrotophos was found to be dependent on the pH, as well as the substitution on the phthalocyanine ring. Strong electron withdrawing groups on the phthalocyanine ring yielded best catalysis as evidenced by the enhancement of the reduction peak current, (~5 fold) compared to the bare glassy carbon electrode. The analysis gave a good detection limit of 1.25 × 10-7 M, and good linearity for the studied concentration range. A high Tafel slope value was obtained, indicating a strong interaction between dicrotophos and the cobalt phthalocyanine complex.
- Full Text:
- Date Issued: 2012
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245832 , vital:51409 , xlink:href="https://doi.org/10.1142/S1088424612501040"
- Description: Electrocatalytic properties of cobalt phthalocyanine (CoPc), cobalt tetra-carboxy phthalocyanine (CoTCPc) and cobalt octa-carboxy (CoOCPc), towards the detection of dicrotophos have been studied. Catalytic behavior towards the reduction of dicrotophos was found to be dependent on the pH, as well as the substitution on the phthalocyanine ring. Strong electron withdrawing groups on the phthalocyanine ring yielded best catalysis as evidenced by the enhancement of the reduction peak current, (~5 fold) compared to the bare glassy carbon electrode. The analysis gave a good detection limit of 1.25 × 10-7 M, and good linearity for the studied concentration range. A high Tafel slope value was obtained, indicating a strong interaction between dicrotophos and the cobalt phthalocyanine complex.
- Full Text:
- Date Issued: 2012
Photophysical and optical limiting properties of a novel distyryl-BODIPY with fused crown ether moieties
- May, Aviwe K, Stone, Justin, Ngoy, Bokolombe P, Mack, John, Nyokong, Tebello, Kimura, Mutsumi, Kobayashi, Nagao
- Authors: May, Aviwe K , Stone, Justin , Ngoy, Bokolombe P , Mack, John , Nyokong, Tebello , Kimura, Mutsumi , Kobayashi, Nagao
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239621 , vital:50749 , xlink:href="https://doi.org/10.1142/S1088424617500869"
- Description: The synthesis and characterization of a crown-ether-substituted 3,5-distyrylBODIPY dye with a 4-dimethylaminophenyl group at the meso-position is reported. The optical limiting properties were investigated at 532 nm, and the dye was found to have enhanced reverse saturable absorption responses during z-scan measurements. Theoretical calculations suggest that this may be due to the large dipole moment that is introduced by the benzo-fused crown ether and 4-dimethylaminophenyl substituents.
- Full Text:
- Date Issued: 2017
- Authors: May, Aviwe K , Stone, Justin , Ngoy, Bokolombe P , Mack, John , Nyokong, Tebello , Kimura, Mutsumi , Kobayashi, Nagao
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239621 , vital:50749 , xlink:href="https://doi.org/10.1142/S1088424617500869"
- Description: The synthesis and characterization of a crown-ether-substituted 3,5-distyrylBODIPY dye with a 4-dimethylaminophenyl group at the meso-position is reported. The optical limiting properties were investigated at 532 nm, and the dye was found to have enhanced reverse saturable absorption responses during z-scan measurements. Theoretical calculations suggest that this may be due to the large dipole moment that is introduced by the benzo-fused crown ether and 4-dimethylaminophenyl substituents.
- Full Text:
- Date Issued: 2017
Synthesis and Photophysical Investigation of Tetraazaporphyrin Substituted with Aggregation‐Induced Emission (AIE) Active Moieties
- Tasso, Thiago T, Furuyama, Taniyuki, Mack, John, Nyokong, Tebello, Kobayashi, Nagao
- Authors: Tasso, Thiago T , Furuyama, Taniyuki , Mack, John , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193553 , vital:45346 , xlink:href="https://doi.org/10.1002/ejic.201500726"
- Description: The synthesis and characterization of free-base and ZnII tetraazaporphyrins with tetraphenylethylene (TPE) or diphenylphenanthrene (DPP) moieties that are known to be aggregation-induced emission (AIE) active is reported. The optical spectra contain the characteristic Q and B absorption bands of Gouterman's four-orbital model and a broad envelope of weaker charge-transfer bands in the 450–600 nm region. The observed fluorescence emission lies beyond 670 nm and originates exclusively from the decay of the S1 state of the macrocycle, regardless of the excitation wavelength used. Theoretical calculations provide further evidence of strong electronic communication between the peripheral TPE or DPP moieties and the central ring. The ZnII complexes were found to have relatively high singlet-oxygen quantum yields.
- Full Text:
- Date Issued: 2015
- Authors: Tasso, Thiago T , Furuyama, Taniyuki , Mack, John , Nyokong, Tebello , Kobayashi, Nagao
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193553 , vital:45346 , xlink:href="https://doi.org/10.1002/ejic.201500726"
- Description: The synthesis and characterization of free-base and ZnII tetraazaporphyrins with tetraphenylethylene (TPE) or diphenylphenanthrene (DPP) moieties that are known to be aggregation-induced emission (AIE) active is reported. The optical spectra contain the characteristic Q and B absorption bands of Gouterman's four-orbital model and a broad envelope of weaker charge-transfer bands in the 450–600 nm region. The observed fluorescence emission lies beyond 670 nm and originates exclusively from the decay of the S1 state of the macrocycle, regardless of the excitation wavelength used. Theoretical calculations provide further evidence of strong electronic communication between the peripheral TPE or DPP moieties and the central ring. The ZnII complexes were found to have relatively high singlet-oxygen quantum yields.
- Full Text:
- Date Issued: 2015
Physicochemical properties of water soluble unsymmetrical phthalocyanine-folic acid conjugates
- Matlou, Gauta G, Kobayashi, Nagao, Kimura, Mutsumi, Nyokong, Tebello
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233240 , vital:50071 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.10.030"
- Description: This work reports on the successful chemical linkage of folic acid (FA) to Zn mono carboxyphenoxy phthalocyanine (1) and Zn mono carboxyphenoxy tri–(tert–butyl) phthalocyanine (2). The amide bond linkage of FA to phthalocyanine (Pc) is achieved for the first time through the FA-NH2 and Pc-COOH and confirmed using FTIR, MS, elemental analysis and NMR. The linked conjugates were found to be water soluble compared to the physical mixtures of FA and Pc, which allowed for studies of singlet oxygen in water. The Pc-FA linked conjugates (1-FA and 2-FA) were found to be singlet oxygen generators with the following singlet oxygen quantum yields: 1-FA = 0.61 and 2-FA = 0.47 in DMSO and 1-FA = 0.17 and 2-FA = 0.12 in water.
- Full Text:
- Date Issued: 2018
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233240 , vital:50071 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.10.030"
- Description: This work reports on the successful chemical linkage of folic acid (FA) to Zn mono carboxyphenoxy phthalocyanine (1) and Zn mono carboxyphenoxy tri–(tert–butyl) phthalocyanine (2). The amide bond linkage of FA to phthalocyanine (Pc) is achieved for the first time through the FA-NH2 and Pc-COOH and confirmed using FTIR, MS, elemental analysis and NMR. The linked conjugates were found to be water soluble compared to the physical mixtures of FA and Pc, which allowed for studies of singlet oxygen in water. The Pc-FA linked conjugates (1-FA and 2-FA) were found to be singlet oxygen generators with the following singlet oxygen quantum yields: 1-FA = 0.61 and 2-FA = 0.47 in DMSO and 1-FA = 0.17 and 2-FA = 0.12 in water.
- Full Text:
- Date Issued: 2018
Photophysical properties of a novel styryl-BODIPY with a fused crown ether moiety
- Stone, Justin, Mack, John, Nyokong, Tebello, Kimura, Mitsumi, Kobayashi, Nagao
- Authors: Stone, Justin , Mack, John , Nyokong, Tebello , Kimura, Mitsumi , Kobayashi, Nagao
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188227 , vital:44736 , xlink:href="https://doi.org/10.1142/S1088424617500699"
- Description: The synthesis and characterization of a crown-ether-substituted 3-styrylBODIPY dye with a 4-isopropylphenyl group at the meso-position is reported. The effect that the incorporation of Na++ ions into the crown ether moiety has on the photophysical properties is investigated.
- Full Text:
- Date Issued: 2018
- Authors: Stone, Justin , Mack, John , Nyokong, Tebello , Kimura, Mitsumi , Kobayashi, Nagao
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188227 , vital:44736 , xlink:href="https://doi.org/10.1142/S1088424617500699"
- Description: The synthesis and characterization of a crown-ether-substituted 3-styrylBODIPY dye with a 4-isopropylphenyl group at the meso-position is reported. The effect that the incorporation of Na++ ions into the crown ether moiety has on the photophysical properties is investigated.
- Full Text:
- Date Issued: 2018
Tuning the physico-electrochemical properties of novel cobalt (II) octa [(3, 5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs
- Agboola, Bolade O, Ozoemena, Kenneth I, Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261692 , vital:53435 , xlink:href="https://doi.org/10.1016/j.carbon.2009.10.023"
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode.
- Full Text:
- Date Issued: 2010
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261692 , vital:53435 , xlink:href="https://doi.org/10.1016/j.carbon.2009.10.023"
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode.
- Full Text:
- Date Issued: 2010
Metal (Co, Fe) tribenzotetraazachlorin–fullerene conjugates
- Ozoemena, Kenneth I, Mamuru, Solomon A, Fukuda, Takamitsu, Kobayashi, Nagao, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Mamuru, Solomon A , Fukuda, Takamitsu , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263464 , vital:53630 , xlink:href="https://doi.org/10.1016/j.elecom.2009.04.011"
- Description: Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C60) complexes of iron (FeHBSTBTAC–C60) and cobalt (CoHBSTBTAC–C60) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO2Bu and C60) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C60 substituent suppressed ORR compared to the –SO2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ∼1 × 108 cm3 mol−1 s−1 and a Tafel slope of −171 mV dec−1.
- Full Text:
- Date Issued: 2009
- Authors: Ozoemena, Kenneth I , Mamuru, Solomon A , Fukuda, Takamitsu , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263464 , vital:53630 , xlink:href="https://doi.org/10.1016/j.elecom.2009.04.011"
- Description: Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C60) complexes of iron (FeHBSTBTAC–C60) and cobalt (CoHBSTBTAC–C60) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO2Bu and C60) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C60 substituent suppressed ORR compared to the –SO2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ∼1 × 108 cm3 mol−1 s−1 and a Tafel slope of −171 mV dec−1.
- Full Text:
- Date Issued: 2009
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- Liang, Xu, Xu, Li, Li, Minzhi, Mack, John, Stone, Justin, Nyokong, Tebello, Jiang, Yu, Kobayashi, Nagao, Zhu, Weihua
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
- Full Text:
- Date Issued: 2015
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
- Full Text:
- Date Issued: 2015