Photophysical properties of a novel styryl-BODIPY with a fused crown ether moiety
- 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.
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- Date Issued: 2018
Photophysical and optical limiting properties of a novel distyryl-BODIPY with fused crown ether moieties
- 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.
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- Date Issued: 2017
Synthesis and photophysical studies of crown ether-bodipy dyes and the fabrication of bodipy embedded fluorescent nanofibers
- Authors: Stone, Justin
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4953 , vital:20746
- Description: This study has three major objectives: 1) to synthesize a series of structurally related BODIPY dyes, 2) to fabricate BODIPY embedded electrospun nanofibers, and 3) to investigate and characterize the photophysical properties of all synthesized BODIPY dyes with a special focus on their ability to generate singlet oxygen. This thesis first explores the acid catalysed condensation reaction to produce two structurally analogous meso-substituted BODIPY dyes based on cuminaldehyde and 4-dimethylaminobenzaldehdye. In order to enhance the rate of ISC and promote the generation of reactive oxygen species bromine atoms were then attached to the BODIPY 2,6-positions. These BODIPY dyes were then embedded in a polystyrene solution and electrospun into nanofibers. The resulting nanofibers were found to be highly fluorescent, but were no longer able to generate singlet oxygen. Ion-sensitive BODIPYs were prepared from the dibrominated BODIPY dyes by employing a modified Knoevenagel condensation reaction to form a styryl bond with 4’-formylbenzo-15-crown-5 at the 3,5-position of the BODIPY core. Changes in the morphology and position of the absorption and emission spectra of these crown ether-styryl BODIPY dyes were observed in the presence of sodium ions. These results imply that crown ether-substituted BODIPY dyes could function as ion sensors.
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- Date Issued: 2017
The changing fortunes of the organ: the viewpoints of church organists in the Anglican churches of Port Elizabeth
- Authors: Stone, Justin
- Date: 2017
- Subjects: Organ (Musical instrument) -- South Africa -- Port Elizabeth Organists -- South Africa -- Port Elizabeth , Church of England -- Organs
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: http://hdl.handle.net/10948/23502 , vital:30569
- Description: This study investigates the changing role of the organ within the Anglican Church of Port Elizabeth. In this study, the term The Church of England is used to refer to both the Anglican Church in England and the Anglican Church (Church of the Province) of Southern Africa. The organ has over many centuries evolved and risen to a place of dominance within the church. Many factors such as political influence, the increase in technology and the use of the organ within the liturgy of the church have contributed to this situation. Equally evident in practices in modern churches and societies is the diminished role of the organ. Again, many factors such as a change in church liturgy, a lack of organists and a negative bias towards the organ have influenced the decrease in the popularity and use of the instrument. In order to prove the rise and fall of the organ a quantitative study in the form of a literature review was employed to trace the organ‟s claim to power as well as the status it gained and to outline the reasons for its decline in power. To investigate this phenomenon, research was conducted in nine selected Anglican churches in Port Elizabeth, that have pipe organs and which were established by the British settlers, along the traditional lines of Anglican churches. The results are discussed and the narratives of the respondents recorded. Findings from the study show that the organ has lost its authoritative voice in the church. The organ is no longer the preferred and only instrument utilized for music and accompaniment within the average Anglican parish service. An urgent and careful response is needed to promote the organ in church services and in the music life of society.
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- Date Issued: 2017
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- 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.
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- Date Issued: 2015
Trends in the TD-DFT calculations of porphyrin and phthalocyanine analogs
- 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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- Date Issued: 2014
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Language: English
- Type: Article
- Identifier: vital:7292 , http://hdl.handle.net/10962/d1020355
- 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. , Original publication is available at http://dx.doi.org/10.1142/S1088424615500492
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