In vitro antimicrobial photodynamic inactivation of multidrugresistant Acinetobacter baumannii biofilm using Protoporphyrin IX and Methylene blue
- Anane, Yaw Adjei, Apalata, Teke, Vasaikar, Sandeep, Okuthe, Grace Emily, Songca, Sandile Phinda
- Authors: Anane, Yaw Adjei , Apalata, Teke , Vasaikar, Sandeep , Okuthe, Grace Emily , Songca, Sandile Phinda
- Date: 2020
- Language: English
- Identifier: http://hdl.handle.net/11260/2273 , vital:41315
- Full Text:
- Authors: Anane, Yaw Adjei , Apalata, Teke , Vasaikar, Sandeep , Okuthe, Grace Emily , Songca, Sandile Phinda
- Date: 2020
- Language: English
- Identifier: http://hdl.handle.net/11260/2273 , vital:41315
- Full Text:
Optimal template removal from molecularly imprinted polymers by pressurized hot water extraction
- Batlokwa, Bareki Shima, Mokgadi, Janes, Nyokong, Tebello, Torto, Nelson
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
- Full Text:
- Date Issued: 2011
Opposing responses elicited by positively charged phthalocyanines in the presence of CdTe quantum dots
- Moeno, Sharon, Nyokong, Tebello
- Authors: Moeno, Sharon , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264506 , vital:53740 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.10.027"
- Description: Tetrapositively charged phthalocyanines and CdTe quantum dots (QDs) capped with thioglycolic acid (TGA) and mercaptopropionic acid (MPA) were synthesized. The response of the tetrapositively charged zinc phthalocyanines in the presence of quantum dots was studied. Aggregation and charge transfer were observed for [tetramethyl-2,(3)-[tetra-(2-mercaptopyridinephthalocyaninato)]zinc(II)]4+ (TmTMPyZnPc), however aggregation proved to be the more prominent process of the two. Fluorescence resonance energy transfer (FRET) was observed with [tetramethyl-2,(3)-[tetra-(2- pyridyloxyphthalocyaninato)]zinc(II)]4+ (TmTPyZnPc). In the FRET study the efficiency of FRET with TmTPyZnPc was determined to be 21% for both MPA and TGA capped CdTe QDs. For the charge transfer study the fluorescence of the quantum dots was quenched by the TmTMPyZnPc used, and from these quenching studies the quenching constants, binding constants and number of binding sites on the quantum dots were determined.
- Full Text:
- Date Issued: 2009
- Authors: Moeno, Sharon , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264506 , vital:53740 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.10.027"
- Description: Tetrapositively charged phthalocyanines and CdTe quantum dots (QDs) capped with thioglycolic acid (TGA) and mercaptopropionic acid (MPA) were synthesized. The response of the tetrapositively charged zinc phthalocyanines in the presence of quantum dots was studied. Aggregation and charge transfer were observed for [tetramethyl-2,(3)-[tetra-(2-mercaptopyridinephthalocyaninato)]zinc(II)]4+ (TmTMPyZnPc), however aggregation proved to be the more prominent process of the two. Fluorescence resonance energy transfer (FRET) was observed with [tetramethyl-2,(3)-[tetra-(2- pyridyloxyphthalocyaninato)]zinc(II)]4+ (TmTPyZnPc). In the FRET study the efficiency of FRET with TmTPyZnPc was determined to be 21% for both MPA and TGA capped CdTe QDs. For the charge transfer study the fluorescence of the quantum dots was quenched by the TmTMPyZnPc used, and from these quenching studies the quenching constants, binding constants and number of binding sites on the quantum dots were determined.
- Full Text:
- Date Issued: 2009
Mechanisms and indicators for assessing the impact of biofuel feedstock production on ecosystem services
- Gasparatos, Alexandros, Romeu-Dalmau, Carla, von Maltitz, Graham P, Johnson, Francis X, Shackleton, Charlie M, Jarzebski, Marcin P, Jumbe, Charles, Ochieng, Caroline, Mudombi, Shakespear, Nyambane, Anne, Willis, Katherine J
- Authors: Gasparatos, Alexandros , Romeu-Dalmau, Carla , von Maltitz, Graham P , Johnson, Francis X , Shackleton, Charlie M , Jarzebski, Marcin P , Jumbe, Charles , Ochieng, Caroline , Mudombi, Shakespear , Nyambane, Anne , Willis, Katherine J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181368 , vital:43727 , xlink:href="https://doi.org/10.1016/j.biombioe.2018.01.024"
- Description: Biofuel feedstock production can be a significant driver of landscape modification, ecosystem change and biodiversity loss. There is growing body of literature that shows how biofuel landscapes provide various ecosystem services (e.g., feedstock for fuel, carbon sequestration) and compromise other ecosystem services (e.g., food, freshwater services). These effects are context-specific and depend largely on prior land use conditions and feedstock production practices. Changes in the flow of ecosystem services due to the conversion of natural and agricultural areas can have ripple effects on human wellbeing. Despite some recent attempts to apply to biofuel settings concepts and methods rooted in the ecosystem services literature, this is the exception rather than the rule within both the biofuel and the ecosystem services research communities. This paper synthesizes the current knowledge about the impact of biofuels on ecosystem services. It focuses especially on the feedstock production phase and outlines the main mechanisms through which landscape conversion affects the provisions of ecosystem services. It proposes conceptually coherent indicators to reflect these mechanisms and offers a critical discussion of key issues at the interface of biofuels and ecosystem services.
- Full Text:
- Date Issued: 2018
- Authors: Gasparatos, Alexandros , Romeu-Dalmau, Carla , von Maltitz, Graham P , Johnson, Francis X , Shackleton, Charlie M , Jarzebski, Marcin P , Jumbe, Charles , Ochieng, Caroline , Mudombi, Shakespear , Nyambane, Anne , Willis, Katherine J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181368 , vital:43727 , xlink:href="https://doi.org/10.1016/j.biombioe.2018.01.024"
- Description: Biofuel feedstock production can be a significant driver of landscape modification, ecosystem change and biodiversity loss. There is growing body of literature that shows how biofuel landscapes provide various ecosystem services (e.g., feedstock for fuel, carbon sequestration) and compromise other ecosystem services (e.g., food, freshwater services). These effects are context-specific and depend largely on prior land use conditions and feedstock production practices. Changes in the flow of ecosystem services due to the conversion of natural and agricultural areas can have ripple effects on human wellbeing. Despite some recent attempts to apply to biofuel settings concepts and methods rooted in the ecosystem services literature, this is the exception rather than the rule within both the biofuel and the ecosystem services research communities. This paper synthesizes the current knowledge about the impact of biofuels on ecosystem services. It focuses especially on the feedstock production phase and outlines the main mechanisms through which landscape conversion affects the provisions of ecosystem services. It proposes conceptually coherent indicators to reflect these mechanisms and offers a critical discussion of key issues at the interface of biofuels and ecosystem services.
- Full Text:
- Date Issued: 2018
Comparative photocatalytic efficiency of oxotitanium (IV) phthalocyanines for the oxidation of 1-hexene
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271193 , vital:54520 , xlink:href="https://doi.org/10.1016/j.molcata.2007.04.005"
- Description: The comparative photocatalytic activities of aryloxy and arylthio tetrasubstituted oxotitanium(IV) phthalocyanine complexes for the oxidation of 1-hexene in DCM are reported for the first time. The singlet oxygen quantum yield, photostability and photocatalytic properties are investigated. The catalysts effectively catalyse 1-hexene to 1,2-epoxyhexane and 1-hexen-3-ol as major and minor products respectively. The photooxidation products are formed via two reaction mechanisms, namely via singlet oxygen (Type II) and radical (Type I) reaction pathways. These are also dependent on the singlet oxygen quantum yields and photostabilities of the phthalocyanines. Complex 1a that is peripherally substituted with phenoxy groups exhibited the best activity in terms of overall performance.
- Full Text:
- Date Issued: 2007
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/271193 , vital:54520 , xlink:href="https://doi.org/10.1016/j.molcata.2007.04.005"
- Description: The comparative photocatalytic activities of aryloxy and arylthio tetrasubstituted oxotitanium(IV) phthalocyanine complexes for the oxidation of 1-hexene in DCM are reported for the first time. The singlet oxygen quantum yield, photostability and photocatalytic properties are investigated. The catalysts effectively catalyse 1-hexene to 1,2-epoxyhexane and 1-hexen-3-ol as major and minor products respectively. The photooxidation products are formed via two reaction mechanisms, namely via singlet oxygen (Type II) and radical (Type I) reaction pathways. These are also dependent on the singlet oxygen quantum yields and photostabilities of the phthalocyanines. Complex 1a that is peripherally substituted with phenoxy groups exhibited the best activity in terms of overall performance.
- Full Text:
- Date Issued: 2007
A comparative photophysicochemical study of phthalocyanines encapsulated in core–shell silica nanoparticles
- Fashina, Adedayo, Amuhaya, Edith, Nyokong, Tebello
- Authors: Fashina, Adedayo , Amuhaya, Edith , Nyokong, Tebello
- Language: English
- Type: text
- Identifier: vital:7271 , http://hdl.handle.net/10962/d1020286 , Original publication is available at http://dx.doi.org/10.1016/j.saa.2014.08.062
- Full Text: false
- Authors: Fashina, Adedayo , Amuhaya, Edith , Nyokong, Tebello
- Language: English
- Type: text
- Identifier: vital:7271 , http://hdl.handle.net/10962/d1020286 , Original publication is available at http://dx.doi.org/10.1016/j.saa.2014.08.062
- Full Text: false
Physicochemical behavior of nanohybrids of mono and tetra substituted carboxyphenoxy phthalocyanine covalently linked to GSH–CdTe/CdS/ZnS quantum dots
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189480 , vital:44850 , xlink:href="https://doi.org/10.1016/j.poly.2014.10.024"
- Description: Zinc monocarboxyphenoxy and tetracarboxyphenoxy phthalocyanines were covalently linked with three different sizes of glutathione capped core/shell/shell {CdTe/CdS/ZnS(4.2), CdTe/CdS/ZnS(5.1) and CdTe/CdS/ZnS(6.7)}; a core shell {CdTe/CdS(3.1)} and core {CdTe(2.4)} quantum dots. The physicochemical behavior and Förster resonance energy transfer (FRET) processes of the nanohybrids were investigated. The highest FRET efficiency was observed with CdTe/CdS/ZnS(6.7) nanohybrids with 98% and the least efficiency was observed with CdTe(2.4) nanohybrids with 85%. The CdTe/CdS/ZnS(6.7) also showed the best physicochemical behavior. These good physicochemical properties make the synthesized nanohybrids viable photosensitizers.
- Full Text:
- Date Issued: 2015
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189480 , vital:44850 , xlink:href="https://doi.org/10.1016/j.poly.2014.10.024"
- Description: Zinc monocarboxyphenoxy and tetracarboxyphenoxy phthalocyanines were covalently linked with three different sizes of glutathione capped core/shell/shell {CdTe/CdS/ZnS(4.2), CdTe/CdS/ZnS(5.1) and CdTe/CdS/ZnS(6.7)}; a core shell {CdTe/CdS(3.1)} and core {CdTe(2.4)} quantum dots. The physicochemical behavior and Förster resonance energy transfer (FRET) processes of the nanohybrids were investigated. The highest FRET efficiency was observed with CdTe/CdS/ZnS(6.7) nanohybrids with 98% and the least efficiency was observed with CdTe(2.4) nanohybrids with 85%. The CdTe/CdS/ZnS(6.7) also showed the best physicochemical behavior. These good physicochemical properties make the synthesized nanohybrids viable photosensitizers.
- Full Text:
- Date Issued: 2015
Photophysical and photochemical studies of long chain-substituted zinc phthalocyanines
- Durmus, Mahmut, Ahsen, Vefa, Nyokong, Tebello
- Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
- Full Text:
- Date Issued: 2007
- Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
- Full Text:
- Date Issued: 2007
Effect of oligomerization on the photochemical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
Food waste generation and potential interventions at Rhodes University, South Africa
- Painter, Kathleen, Thondhlana, Gladman, Kua, Harn W
- Authors: Painter, Kathleen , Thondhlana, Gladman , Kua, Harn W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67733 , vital:29135 , https://doi.org/10.1016/j.wasman.2016.07.013
- Description: Publisher version , Estimation of food waste generation represents the first step when considering efforts to reduce waste generation and monitor food waste reduction against set targets. This study reports on an estimation of food waste generated in university dining halls at Rhodes University, South Africa. Daily food waste generation was estimated at about 555 g per student or 2 tonnes across all sample dining halls, translating to about 450 tonnes per year. The results show that food waste is influenced by an array of contextual factors, including distance to dining hall, gender composition of hall and meal times and meal options. It is estimated that the university could save up to US$ 80 000 annually for every 10% reduction in the current rate of food waste generation. Possible educational, technical and administrative interventions for food waste reduction are discussed.
- Full Text: false
- Date Issued: 2016
- Authors: Painter, Kathleen , Thondhlana, Gladman , Kua, Harn W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67733 , vital:29135 , https://doi.org/10.1016/j.wasman.2016.07.013
- Description: Publisher version , Estimation of food waste generation represents the first step when considering efforts to reduce waste generation and monitor food waste reduction against set targets. This study reports on an estimation of food waste generated in university dining halls at Rhodes University, South Africa. Daily food waste generation was estimated at about 555 g per student or 2 tonnes across all sample dining halls, translating to about 450 tonnes per year. The results show that food waste is influenced by an array of contextual factors, including distance to dining hall, gender composition of hall and meal times and meal options. It is estimated that the university could save up to US$ 80 000 annually for every 10% reduction in the current rate of food waste generation. Possible educational, technical and administrative interventions for food waste reduction are discussed.
- Full Text: false
- Date Issued: 2016
Comprehensive data on the mechanical properties and biodegradation profile of polylactide composites developed for hard tissue repairs
- Abraham K. Aworinde, Samson O. Adeosun, Festus A. Oyawale, Eyere Emagbetere, Felix A. Ishola, Obafemi Olatunji, Stephen A. Akinlab, Sunday O. Oyedepo, Oluseyi O. Ajayi, Esther T. Akinlabi
- Authors: Abraham K. Aworinde , Samson O. Adeosun , Festus A. Oyawale , Eyere Emagbetere , Felix A. Ishola , Obafemi Olatunji , Stephen A. Akinlab , Sunday O. Oyedepo , Oluseyi O. Ajayi , Esther T. Akinlabi
- Date: 2020
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/4152 , vital:44032
- Full Text:
- Authors: Abraham K. Aworinde , Samson O. Adeosun , Festus A. Oyawale , Eyere Emagbetere , Felix A. Ishola , Obafemi Olatunji , Stephen A. Akinlab , Sunday O. Oyedepo , Oluseyi O. Ajayi , Esther T. Akinlabi
- Date: 2020
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/4152 , vital:44032
- Full Text:
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
Synthesis and photophysical properties of 1, 1′-binaphthol substituted phthalocyanines
- Canlica, Meylude, Nyokong, Tebello
- Authors: Canlica, Meylude , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249148 , vital:51782 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.034"
- Description: We report on the synthesis, characterization and photophysical properties of a new symmetrically tetra substituted {at non-peripheral positions with tetra(1,1′-bi-binaphtoxy)} phthalocyanines containing H2, Mg(II), Al(III)Cl, Si(IV)Cl2 in the central cavity. The synthesized compounds were characterized by the elemental analyses, UV–Vis, FT-IR and 1H NMR spectroscopies. The fluorescence quantum yields, triplet quantum yields and lifetimes of the newly synthesized H2, Mg, Al, and Si phthalocyanines were explored. Triplet quantum yields ranged from 0.24 to 0.54. The triplet lifetime for the silicon phthalocyanine derivative was the highest ever reported for a phthalocyanine (∼3.5 ms).
- Full Text:
- Date Issued: 2010
- Authors: Canlica, Meylude , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249148 , vital:51782 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.034"
- Description: We report on the synthesis, characterization and photophysical properties of a new symmetrically tetra substituted {at non-peripheral positions with tetra(1,1′-bi-binaphtoxy)} phthalocyanines containing H2, Mg(II), Al(III)Cl, Si(IV)Cl2 in the central cavity. The synthesized compounds were characterized by the elemental analyses, UV–Vis, FT-IR and 1H NMR spectroscopies. The fluorescence quantum yields, triplet quantum yields and lifetimes of the newly synthesized H2, Mg, Al, and Si phthalocyanines were explored. Triplet quantum yields ranged from 0.24 to 0.54. The triplet lifetime for the silicon phthalocyanine derivative was the highest ever reported for a phthalocyanine (∼3.5 ms).
- Full Text:
- Date Issued: 2010
Asymmetrical zinc phthalocyanine conjugated to various nanomaterials for applications in phototransformation of organic pollutants and photoinactivation of bacteria
- Mgidlana, Sithi, Openda, Yolande Ikala, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360344 , vital:65081 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.134850"
- Description: Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.
- Full Text:
- Date Issued: 2023
- Authors: Mgidlana, Sithi , Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360344 , vital:65081 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.134850"
- Description: Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.
- Full Text:
- Date Issued: 2023
Synthetic pathways to water-soluble phthalocyanines and close analogs
- Dumoulin, Fabienne, Durmus, Mahmut, Ahsen, Vefa, Nyokong, Tebello
- Authors: Dumoulin, Fabienne , Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249082 , vital:51776 , xlink:href="https://doi.org/10.1016/j.ccr.2010.05.002"
- Description: The different types of water-soluble phthalocyanines are presented and their synthesis is reviewed.
- Full Text:
- Date Issued: 2010
- Authors: Dumoulin, Fabienne , Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249082 , vital:51776 , xlink:href="https://doi.org/10.1016/j.ccr.2010.05.002"
- Description: The different types of water-soluble phthalocyanines are presented and their synthesis is reviewed.
- Full Text:
- Date Issued: 2010
Adsorption and separation of platinum and palladium by polyamine functionalized polystyrene-based beads and nanofibers
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Kempgens, Pierre F M, Antunes, Edith M, Torto, Nelson, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
Nanosecond nonlinear optical limiting properties of new trinuclear lanthanide phthalocyanines in solution and as thin films
- Sekhosana, Kutloano Edward, Amuhaya, Edith, Nyokong, Tebello
- Authors: Sekhosana, Kutloano Edward , Amuhaya, Edith , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7267 , http://hdl.handle.net/10962/d1020276
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.08.047
- Full Text: false
- Authors: Sekhosana, Kutloano Edward , Amuhaya, Edith , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7267 , http://hdl.handle.net/10962/d1020276
- Description: 2,4,6-Tris[3-thio-9,10,16,17,23,24-hexa(4-tertbutylphenoxy) phthalocyaninato ytterbium (III) chloride]-s-triazin (3) and its lutetium counterpart (4) were synthesized. The nonlinear optical behavior of 3 and 4 were characterized in solution and when embedded in polymer as thin films. Thin films of complexes 3 and 4 in poly(bisphenol A carbonate) showed improved nonlinear optical properties when compared to solution. Complex 3 showed a lower threshold for optical limiting intensity (Ilim) than complex 4, and for phthalocyanines in general. Ilim values were even lower in films compared to solutions. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.08.047
- Full Text: false
Reverse saturation absorption spectra and optical limiting properties of chlorinated tetrasubstituted phthalocyanines containing different metals
- Tuhl, Ahmad, Manaa, Hacene, Makhseed, Saad, Al-Awadi, Nouria, Matthew, Jacob, Ibrahim, Hamada Mohamed, Nyokong, Tebello, Behbehani, Haider
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
In vitro toxicity testing of zinc tetrasulfophthalocyanines in fibroblast and keratinocyte cells for the treatment of melanoma cancer by photodynamic therapy
- Maduray, Kaminee, Karsten, Alta, Odhay, Bharti, Nyokong, Tebello
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
Synthesis, electrochemical and photochemical properties of unsymmetrically substituted zinc phthalocyanine complexes
- Matlaba, Pulane M, Nyokong, Tebello
- Authors: Matlaba, Pulane M , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289650 , vital:56658 , xlink:href="https://doi.org/10.1016/S0277-5387(02)01226-3"
- Description: The synthesis of symmetrically and unsymmetrically substituted zinc phthalocyanine (ZnPc) derivatives are reported. The ZnPc derivatives are synthesized by ring expansion of subphthalocyanine complexes. Ring substitution is effected with tert-butyl phenol, naphthol and hydroxybenzoic acid. Comparison of the redox potentials for complexes substituted with varying numbers of tert-butyl phenol: 1 (complex 5), 2 (complex 6), 3 (complex 7), 6 (complex 8) and 8 (complex 9) shows that the complexes with the highest number of substituents are more difficult to oxidize and easier to reduce. All the reported complexes are relatively photostable, with photobleaching quantum yields of the order of 10−5. Singlet oxygen quantum yields for the complexes ranged from 0.22 to 0.68.
- Full Text:
- Date Issued: 2002
- Authors: Matlaba, Pulane M , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289650 , vital:56658 , xlink:href="https://doi.org/10.1016/S0277-5387(02)01226-3"
- Description: The synthesis of symmetrically and unsymmetrically substituted zinc phthalocyanine (ZnPc) derivatives are reported. The ZnPc derivatives are synthesized by ring expansion of subphthalocyanine complexes. Ring substitution is effected with tert-butyl phenol, naphthol and hydroxybenzoic acid. Comparison of the redox potentials for complexes substituted with varying numbers of tert-butyl phenol: 1 (complex 5), 2 (complex 6), 3 (complex 7), 6 (complex 8) and 8 (complex 9) shows that the complexes with the highest number of substituents are more difficult to oxidize and easier to reduce. All the reported complexes are relatively photostable, with photobleaching quantum yields of the order of 10−5. Singlet oxygen quantum yields for the complexes ranged from 0.22 to 0.68.
- Full Text:
- Date Issued: 2002