X-ray photoelectron spectroscopy analysis of the effect of alkyl-and arylthio substituents on manganese phthalocyanines for self-assembled monolayer formation on gold
- Coates, Megan, Nyokong, Tebello
- Authors: Coates, Megan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190490 , vital:44999 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.019"
- Description: Self-assembled monolayers of an octa-substituted alkylthio and arylthio manganese phthalocyanines were formed on gold. X-ray photoelectron spectroscopy was used to analyse both of the phthalocyanine layers on gold. Approximately 60% of the sulphur groups in the aryl substituted-SAM surface were bound to gold through the cleavage of the C S bond, as opposed to only 37% for the alkyl substituted-SAM.
- Full Text:
- Date Issued: 2013
- Authors: Coates, Megan , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190490 , vital:44999 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.019"
- Description: Self-assembled monolayers of an octa-substituted alkylthio and arylthio manganese phthalocyanines were formed on gold. X-ray photoelectron spectroscopy was used to analyse both of the phthalocyanine layers on gold. Approximately 60% of the sulphur groups in the aryl substituted-SAM surface were bound to gold through the cleavage of the C S bond, as opposed to only 37% for the alkyl substituted-SAM.
- Full Text:
- Date Issued: 2013
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
Zinc phthalocyanine photocatalyzed oxidation of cyclohexene
- Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289399 , vital:56629 , xlink:href="https://doi.org/10.1016/j.molcata.2004.05.010"
- Description: Cyclohexene photooxidation catalyzed by zinc phthalocyanine (ZnPc) using either red or white light results in the formation of cyclohexenone, cyclohexenol, trans-cyclohexanediol, cyclohexene oxide and cyclohexene hydroperoxide. The product yield increased as follows: cyclohexenone > cyclohexenol > trans-cyclohexanediol > cyclohexene oxide > cyclohexene hydroperoxide. The mechanism for the formation of these products involves both singlet oxygen and radicals (Type II and Type I mechanisms, respectively). The catalyst degraded slowly when low light intensities were employed. The product yields were found to depend on the light intensity, the nature of solvent, irradiation time and the rate of photodegradation of the catalyst.
- Full Text:
- Date Issued: 2004
- Authors: Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289399 , vital:56629 , xlink:href="https://doi.org/10.1016/j.molcata.2004.05.010"
- Description: Cyclohexene photooxidation catalyzed by zinc phthalocyanine (ZnPc) using either red or white light results in the formation of cyclohexenone, cyclohexenol, trans-cyclohexanediol, cyclohexene oxide and cyclohexene hydroperoxide. The product yield increased as follows: cyclohexenone > cyclohexenol > trans-cyclohexanediol > cyclohexene oxide > cyclohexene hydroperoxide. The mechanism for the formation of these products involves both singlet oxygen and radicals (Type II and Type I mechanisms, respectively). The catalyst degraded slowly when low light intensities were employed. The product yields were found to depend on the light intensity, the nature of solvent, irradiation time and the rate of photodegradation of the catalyst.
- Full Text:
- Date Issued: 2004
“Turn on” fluorescence enhancement of Zn octacarboxyphthaloyanine-graphene oxide conjugates by hydrogen peroxide
- Shumba, Munyaradzi, Mashazi, Philani N, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240875 , vital:50881 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240875 , vital:50881 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
“Turn on” fluorescence enhancement of Zn octacarboxyphthaloyanine-graphene oxide conjugates by hydrogen peroxide
- Shumba, Munyaradzi, Mashazi, Philani N, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190438 , vital:44994 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyaninereduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190438 , vital:44994 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyaninereduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016