Photocatalytic behaviour of tantalum (V) phthalocyanines in the presence of gold nanoparticles towards the oxidation of cyclohexene
- Chauke, Vongani P, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
- Full Text:
- Date Issued: 2011
Photophysical behavior of zinc monoaminophthalocyanines linked to mercaptopropionic acid-capped CdTe quantum dots
- D'Souza, Sarah, Antunes, Edith M, Litwinski, Christian, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
Synthesis and photophysical studies of CdTe quantum dot-monosubstituted zinc phthalocyanine conjugates
- D'Souza, Sarah, Antunes, Edith M, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247825 , vital:51621 , xlink:href="https://doi.org/10.1016/j.ica.2010.12.027"
- Description: The linkage of unsymmetrically monosubstituted 4-aminophenoxy zinc phthalocyanine (ZnAPPc, 5) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide, which facilitate formation of an amide bond to form the QD–ZnAPPc-linked conjugate. The formation of the amide bond was confirmed using Raman and IR spectroscopies. Atomic force microscopy (AFM) and UV–Vis spectroscopy were used further to characterise the conjugate. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QD–ZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates. The linked L-cys and TGA QDs conjugates (QD–ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247825 , vital:51621 , xlink:href="https://doi.org/10.1016/j.ica.2010.12.027"
- Description: The linkage of unsymmetrically monosubstituted 4-aminophenoxy zinc phthalocyanine (ZnAPPc, 5) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide, which facilitate formation of an amide bond to form the QD–ZnAPPc-linked conjugate. The formation of the amide bond was confirmed using Raman and IR spectroscopies. Atomic force microscopy (AFM) and UV–Vis spectroscopy were used further to characterise the conjugate. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QD–ZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates. The linked L-cys and TGA QDs conjugates (QD–ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked.
- Full Text:
- Date Issued: 2011
Unquenched fluorescence lifetime for β-phenylthio substituted zinc phthalocyanine upon conjugation to gold nanoparticles
- Forteath, Shaun, Antunes, Edith M, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
- Full Text:
- Date Issued: 2012
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245774 , vital:51404 , xlink:href="https://doi.org/10.1016/j.poly.2011.12.015"
- Description: Photoinduced processes in phthalocyanine-functionalized gold nanoparticles have been investigated by spectroscopic measurements. The zinc phthalocyanine used contained four phenylthio peripheral substituents (ZnPc(SPh)4). The conjugates formed are represented as ZnPc(SPh)4–AuNP. The absorption spectrum of the ZnPc(SPh)4–AuNP shows a broadening of the phthalocyanine Q-band absorption, probably due to a tight packing of the phthalocyanines on the gold nanoparticle surface. For the attached phthalocyanines, the two fluorescence lifetimes obtained by time-correlated single photon counting (TCSPC) were determined to be both longer and shorter than that of the free Pc. The fluorescence lifetimes were resolved using time resolved fluorescence spectroscopy (TRES).
- Full Text:
- Date Issued: 2012
Synthesis and photophysicochemical properties of novel zinc phthalocyanines mono substituted with carboxyl containing functional groups
- Rapulenyane, Nomasonto, Antunes, Edith M, Masilela, Nkosiphile, Nyokong, Tebello
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242389 , vital:51037 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.09.007"
- Description: This work reports on the synthesis and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines (complexes 8, 10 and 11) and their symmetrically substituted counterparts (complexes 9, 12 and 13). The new complexes and their counterparts were successfully structurally characterized by IR, NMR, mass spectral and elemental analyses. Low fluorescence quantum yields (0.032) and lifetimes (0.91 ns) were obtained for the symmetrical ZnOTPc (complex 9) compared to the higher fluorescence quantum yields (0.15, 0.13, 0.10, 0.09 and 0.29) and lifetimes (4.4, 1.69, 1.69, 2.16 and 3.23 ns) obtained for ZnMPCPc (8), ZnTDTPc (12), ZnMCapPc (10), ZnMCafPc (11) and ZnTCPPc (13), respectively. All the complexes showed the ability to produce singlet oxygen with the highest triplet quantum yields obtained for 8 and 10 (0.80 and 0.65 respectively). High triplet lifetimes (109–286 μs) were obtained for all complexes. Complex 8 showed the longest triplet and fluorescence lifetimes as well the largest triplet state and singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2012
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Masilela, Nkosiphile , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242389 , vital:51037 , xlink:href="https://doi.org/10.1016/j.jphotochem.2012.09.007"
- Description: This work reports on the synthesis and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines (complexes 8, 10 and 11) and their symmetrically substituted counterparts (complexes 9, 12 and 13). The new complexes and their counterparts were successfully structurally characterized by IR, NMR, mass spectral and elemental analyses. Low fluorescence quantum yields (0.032) and lifetimes (0.91 ns) were obtained for the symmetrical ZnOTPc (complex 9) compared to the higher fluorescence quantum yields (0.15, 0.13, 0.10, 0.09 and 0.29) and lifetimes (4.4, 1.69, 1.69, 2.16 and 3.23 ns) obtained for ZnMPCPc (8), ZnTDTPc (12), ZnMCapPc (10), ZnMCafPc (11) and ZnTCPPc (13), respectively. All the complexes showed the ability to produce singlet oxygen with the highest triplet quantum yields obtained for 8 and 10 (0.80 and 0.65 respectively). High triplet lifetimes (109–286 μs) were obtained for all complexes. Complex 8 showed the longest triplet and fluorescence lifetimes as well the largest triplet state and singlet oxygen quantum yields.
- Full Text:
- Date Issued: 2012
Comparative behavior of conjugates of tantalum phthalocyanines with gold nanoparticles or single walled carbon nanotubes towards bisphenol A electrocatalysis
- Chauke, Vongani P, Antunes, Edith M, Nyokong, Tebello
- Authors: Chauke, Vongani P , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247152 , vital:51551 , xlink:href="https://doi.org/10.1016/j.jelechem.2011.06.019"
- Description: The characterization of tantalum phthalocyanine conjugates with gold nanoparticles and single wall carbon nanotubes as well as their electrocatalytic oxidation of bisphenol A is hereby presented. The formation of the conjugates was confirmed by X-ray diffraction and transmission electron microscope techniques. Single walled carbon nanotube conjugates of TaPc complexes showed the best catalysis as well as less passivation for bisphenol A detection and significant recovery of ∼98% compared to gold nanoparticle conjugates.
- Full Text:
- Date Issued: 2011
- Authors: Chauke, Vongani P , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247152 , vital:51551 , xlink:href="https://doi.org/10.1016/j.jelechem.2011.06.019"
- Description: The characterization of tantalum phthalocyanine conjugates with gold nanoparticles and single wall carbon nanotubes as well as their electrocatalytic oxidation of bisphenol A is hereby presented. The formation of the conjugates was confirmed by X-ray diffraction and transmission electron microscope techniques. Single walled carbon nanotube conjugates of TaPc complexes showed the best catalysis as well as less passivation for bisphenol A detection and significant recovery of ∼98% compared to gold nanoparticle conjugates.
- Full Text:
- Date Issued: 2011
Cyclic voltammetry and spectroelectrochemistry of a novel manganese phthalocyanine substituted with hexynyl groups
- Quinton, Damien, Antunes, Edith M, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
Investigation of homogeneous photosensitized oxidation activities of palladium and platinum octasubstituted phthalocyanines
- Ogunbayo, Taofeek B, Antunes, Edith M, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
- Authors: Ogunbayo, Taofeek B , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248394 , vital:51682 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.008"
- Description: Photosensitized oxidation of 4-nitrophenol was studied in organic solutions with seven octasubstituted thio and aryloxy palladium and platinum phthalocyanines acting as photosensitizers. Kinetic studies conducted also showed that the complexes have different singlet oxygen quenching constants with direct implication on the quantum yield of photodegradation of 4-nitrophenol (Φ4-NP). Palladium analogues gave better results than the platinum analogues in terms of Φ4-NP with palladium-(dodecylthio)phthalocyanine giving the highest yield of 1.8 × 10−3. Gas chromatography (GC) and liquid chromatography connected to a mass spectrometer (LC–MS) were used to confirm the photodegradation products which were hydroquinone and 1,4-benzoquinone.
- Full Text:
- Date Issued: 2011
Physicochemical properties of a zinc phthalocyanine – pyrene conjugate adsorbed onto single walled carbon nanotubes
- Ogbodu, Racheal O, Antunes, Edith M, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7328 , http://hdl.handle.net/10962/d1020589
- Description: A conjugate between zinc monoamino phthalocyanine (ZnMAPc) and pyrene (Py) represented as ZnMAPc–Py (complex 3) was synthesized and characterized by various spectroscopic techniques and by elemental analysis. This manuscript also reports on the photochemical and photophysical properties of 3. This new compound exhibited higher triplet, fluorescence and singlet oxygen quantum yields in comparison to the phthalocyanine alone, hence showing the advantages of attaching pyrene to the Pc without breaking the conjugation. We also observed a decrease in photophysical parameters upon adsorbing the ZnMAPc–Py complex onto single walled carbon nanotubes (SWCNT). However, ZnMAPc–Py still generated some singlet oxygen when adsorbed onto SWCNT. , Original publication is available at http://dx.doi.org/10.1039/C3DT50335F
- Full Text:
- Authors: Ogbodu, Racheal O , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7328 , http://hdl.handle.net/10962/d1020589
- Description: A conjugate between zinc monoamino phthalocyanine (ZnMAPc) and pyrene (Py) represented as ZnMAPc–Py (complex 3) was synthesized and characterized by various spectroscopic techniques and by elemental analysis. This manuscript also reports on the photochemical and photophysical properties of 3. This new compound exhibited higher triplet, fluorescence and singlet oxygen quantum yields in comparison to the phthalocyanine alone, hence showing the advantages of attaching pyrene to the Pc without breaking the conjugation. We also observed a decrease in photophysical parameters upon adsorbing the ZnMAPc–Py complex onto single walled carbon nanotubes (SWCNT). However, ZnMAPc–Py still generated some singlet oxygen when adsorbed onto SWCNT. , Original publication is available at http://dx.doi.org/10.1039/C3DT50335F
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The development of catalytic oxovanadium(IV)-containing microspheres for the oxidation of various organosulfur compounds
- Ogunlaja, Adeniyi S, Khene, M Samson, Antunes, Edith M, Nyokong, Tebello, Torto, Nelson, Tshentu, Zenixole R
- Authors: Ogunlaja, Adeniyi S , Khene, M Samson , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Language: English
- Type: Article
- Identifier: vital:7324 , http://hdl.handle.net/10962/d1020574
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil. , Original publication is available at http://dx.doi.org/10.1016/j.apcata.2013.05.004
- Full Text: false
- Authors: Ogunlaja, Adeniyi S , Khene, M Samson , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Language: English
- Type: Article
- Identifier: vital:7324 , http://hdl.handle.net/10962/d1020574
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil. , Original publication is available at http://dx.doi.org/10.1016/j.apcata.2013.05.004
- Full Text: false
Photophysical Properties of Zinc Tetracarboxy Phthalocyanines Conjugated to Magnetic Nanoparticles
- Modisha, Phillimon, Antunes, Edith M, Nyokong, Tebello
- Authors: Modisha, Phillimon , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7254 , http://hdl.handle.net/10962/d1020263
- Description: Magnetite nanoparticles (MNPs) were synthesised by the co-precipitation method and coated with amino functional groups which allowed for amide bond formation with the carboxylic acid groups on zinc tetra- or octa-carboxyphthalocyanine (ZnTCPc or ZnOCPc respectively). The absorption spectra of ZnTCPc linked to MNPs showed a reduction in aggregation, while the photophysical parameters (Φ T , τ T and ΦΔ) of ZnTCPc or ZnOCPc increased upon linking with the MNPs. , Original publication is available at http://dx.doi.org/10.1166/jnn.2015.9247
- Full Text: false
- Authors: Modisha, Phillimon , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7254 , http://hdl.handle.net/10962/d1020263
- Description: Magnetite nanoparticles (MNPs) were synthesised by the co-precipitation method and coated with amino functional groups which allowed for amide bond formation with the carboxylic acid groups on zinc tetra- or octa-carboxyphthalocyanine (ZnTCPc or ZnOCPc respectively). The absorption spectra of ZnTCPc linked to MNPs showed a reduction in aggregation, while the photophysical parameters (Φ T , τ T and ΦΔ) of ZnTCPc or ZnOCPc increased upon linking with the MNPs. , Original publication is available at http://dx.doi.org/10.1166/jnn.2015.9247
- Full Text: false
Polyamide nanofiber membranes functionalized with zinc phthalocyanines
- Goethals, Annelies, Mugadza, Tawanda, Arslanoglu, Yasin, Zugle, Ruphino, Antunes, Edith M, Hulle, Stijn W H Van, Nyokong, Tebello, Clerck, Karen De
- Authors: Goethals, Annelies , Mugadza, Tawanda , Arslanoglu, Yasin , Zugle, Ruphino , Antunes, Edith M , Hulle, Stijn W H Van , Nyokong, Tebello , Clerck, Karen De
- Language: English
- Type: Article
- Identifier: vital:7313 , http://hdl.handle.net/10962/d1020539
- Description: Electrospinning is an efficient method for the production of polyamide nanofiber membranes that are suitable for water filtration. Previous studies have shown that nanofiber membranes have high clean water permeability. The pathogen removal efficiency can be improved by functionalization with (organic) biocides. However, these membranes, like other membranes, are vulnerable to fouling which reduces the filtration efficiency. Therefore the present article investigates the potential of zinc phthalocyanines, which can produce singlet oxygen in the presence of visible light, as a functionalizing agent. The polyamide nanofiber membranes were functionalized with phthalocyanines using both a pre-functionalizing and post-functionalizing method. Only the post-functionalization method shows to result in nanofiber membranes capable of producing singlet oxygen. After 30 min 45% of 1,2-diphenylisobenzofuran (DPBF), used as an oxygen quencher, was removed by reaction with singlet oxygen. This resulted in a removal rate of 0.33 mol DBPF mol−1Zn min−1. During short term leaching tests, phthalocyanines could not be detected. , Original publication is available at http://dx.doi.org/10.1002/app.40486
- Full Text: false
- Authors: Goethals, Annelies , Mugadza, Tawanda , Arslanoglu, Yasin , Zugle, Ruphino , Antunes, Edith M , Hulle, Stijn W H Van , Nyokong, Tebello , Clerck, Karen De
- Language: English
- Type: Article
- Identifier: vital:7313 , http://hdl.handle.net/10962/d1020539
- Description: Electrospinning is an efficient method for the production of polyamide nanofiber membranes that are suitable for water filtration. Previous studies have shown that nanofiber membranes have high clean water permeability. The pathogen removal efficiency can be improved by functionalization with (organic) biocides. However, these membranes, like other membranes, are vulnerable to fouling which reduces the filtration efficiency. Therefore the present article investigates the potential of zinc phthalocyanines, which can produce singlet oxygen in the presence of visible light, as a functionalizing agent. The polyamide nanofiber membranes were functionalized with phthalocyanines using both a pre-functionalizing and post-functionalizing method. Only the post-functionalization method shows to result in nanofiber membranes capable of producing singlet oxygen. After 30 min 45% of 1,2-diphenylisobenzofuran (DPBF), used as an oxygen quencher, was removed by reaction with singlet oxygen. This resulted in a removal rate of 0.33 mol DBPF mol−1Zn min−1. During short term leaching tests, phthalocyanines could not be detected. , Original publication is available at http://dx.doi.org/10.1002/app.40486
- Full Text: false
Photophysichochemical behavior of carbazole derivatized zinc phthalocyanine in the presence of ZnO microparticles and when embedded in electrospun fibers
- Khoza, Phindile, Antunes, Edith M, Nyokong, Tebello
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7303 , http://hdl.handle.net/10962/d1020380
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2013.12.019
- Full Text: false
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7303 , http://hdl.handle.net/10962/d1020380
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2013.12.019
- Full Text: false
Surface modification of silica-coated gadolinium oxide nanoparticles with zinc tetracarboxyphenoxy phthalocyanine for the photodegradation of Orange G
- Ledwaba, Mpho, Masilela, Nkosiphile, Nyokong, Tebello, Antunes, Edith M
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7249 , http://hdl.handle.net/10962/d1020255
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics. , Original publication is available at http://dx.doi.org/10.1016/j.molcata.2015.03.023
- Full Text: false
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7249 , http://hdl.handle.net/10962/d1020255
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics. , Original publication is available at http://dx.doi.org/10.1016/j.molcata.2015.03.023
- Full Text: false
Synthesis and characterization of Na(Y,Gd)F4 upconversion nanoparticles and an investigation of their effects on the photophysical properties of an unsubstituted tetrathiophenoxy phthalocyanine
- Taylor, Jessica M, Litwinski, Christian, Nyokong, Tebello, Antunes, Edith M
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7253 , http://hdl.handle.net/10962/d1020261
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs. , Original publication is available at http://dx.doi.org/10.1007/s11051-015-2889-5
- Full Text: false
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7253 , http://hdl.handle.net/10962/d1020261
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs. , Original publication is available at http://dx.doi.org/10.1007/s11051-015-2889-5
- Full Text: false
Photophysical properties of a new water soluble tetra thiamine substituted zinc phthalocyanine conjugated to gold nanorods of different aspect ratios
- Mthethwa, Thandekile, Antunes, Edith M, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7302 , http://hdl.handle.net/10962/d1020379
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods. , Original publication is available at http://dx.doi.org/10.1039/C4DT00197D , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
- Full Text:
- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7302 , http://hdl.handle.net/10962/d1020379
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods. , Original publication is available at http://dx.doi.org/10.1039/C4DT00197D , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
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Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold
- Coates, Megan, Antunes, Edith M, Nyokong, Tebello
- Authors: Coates, Megan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261144 , vital:53363 , xlink:href="https://doi.org/10.1142/S1088424610002471"
- Description: Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
- Full Text:
- Date Issued: 2010
- Authors: Coates, Megan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261144 , vital:53363 , xlink:href="https://doi.org/10.1142/S1088424610002471"
- Description: Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
- Full Text:
- Date Issued: 2010
Photophysical study of a covalently linked quantum dot–low symmetry phthalocyanine conjugate
- Chidawanyika, Wadzanai J U, Litwinski, Christian, Antunes, Edith M, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai J U , Litwinski, Christian , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261641 , vital:53430 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.03.008"
- Description: The linkage of a low symmetry phthalocyanine, ZnttbIPc to mercaptopropionic acid (MPA) capped CdTe quantum dots has been achieved using a coupling agent, dicyclohexylcarbodiimide (DCC), to facilitate formation of an amide bond. UV–vis, Raman and IR spectroscopic studies on the linked (QD:ZnttbIPc-linked) conjugate suggest the reaction was a success. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnttbIPc in both the linked (QD:ZnttbIPc-linked) and mixed (QD:ZnttbIPc-mixed) conjugates. The linked complex (QD:ZnttbIPc-linked) gave the largest FRET efficiency hence showing the advantages of covalent linking. Photophysicochemical properties of the phthalocyanine were improved in the presence of the QDs i.e. for QD:ZnttbIPc-mixed. Fluorescence lifetimes of QDs were unchanged in QD:ZnttbIPc-mixed and decreased for QD:ZnttbIPc-linked.
- Full Text:
- Date Issued: 2010
- Authors: Chidawanyika, Wadzanai J U , Litwinski, Christian , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261641 , vital:53430 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.03.008"
- Description: The linkage of a low symmetry phthalocyanine, ZnttbIPc to mercaptopropionic acid (MPA) capped CdTe quantum dots has been achieved using a coupling agent, dicyclohexylcarbodiimide (DCC), to facilitate formation of an amide bond. UV–vis, Raman and IR spectroscopic studies on the linked (QD:ZnttbIPc-linked) conjugate suggest the reaction was a success. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnttbIPc in both the linked (QD:ZnttbIPc-linked) and mixed (QD:ZnttbIPc-mixed) conjugates. The linked complex (QD:ZnttbIPc-linked) gave the largest FRET efficiency hence showing the advantages of covalent linking. Photophysicochemical properties of the phthalocyanine were improved in the presence of the QDs i.e. for QD:ZnttbIPc-mixed. Fluorescence lifetimes of QDs were unchanged in QD:ZnttbIPc-mixed and decreased for QD:ZnttbIPc-linked.
- Full Text:
- Date Issued: 2010
Photooxidation of 4-chlorophenol sensitized by lutetium tetraphenoxy phthalocyanine anchored on electrospun polystyrene polymer fiber
- Zugle, Ruphino, Antunes, Edith M, Khene, Samson M, Nyokong, Tebello
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
Nonlinear optical behavior of metal octaphenoxy phthalocyanines
- Sanusi, Sikiru O, Antunes, Edith M, Nyokong, Tebello
- Authors: Sanusi, Sikiru O , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241717 , vital:50963 , xlink:href="https://doi.org/10.1142/S1088424613500715"
- Description: In this work, we investigated the nonlinear optical absorption properties of chloroaluminum, chlorogallium, chloroindium, zinc and lead octaphenoxy phthalocyanines in a dimethyl sulphoxide solution using 5 ns pulses at 532 nm. Using the Z-scan technique, the nonlinear optical properties and the excited state absorption cross-sections were determined by fitting the Z-scan data. The k value was the highest for Pb derivative at 211, making it the best nonlinear optical material. In terms of hyperpolarizability, Pb derivative (containing a larger central metal) also gave the largest value followed by aluminum derivative (containing a small central metal). The distortion of the ring caused by the central metal is used to explain the hyperpolarizability values. Large nonlinear absorption coefficient values, βeff, in the range of 3.558–4.763 × 10-9 cm.W-1 and low saturation fluence values, Fsat between 21.5–38.5 mJ.cm-2, were obtained for these samples.
- Full Text:
- Date Issued: 2013
- Authors: Sanusi, Sikiru O , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241717 , vital:50963 , xlink:href="https://doi.org/10.1142/S1088424613500715"
- Description: In this work, we investigated the nonlinear optical absorption properties of chloroaluminum, chlorogallium, chloroindium, zinc and lead octaphenoxy phthalocyanines in a dimethyl sulphoxide solution using 5 ns pulses at 532 nm. Using the Z-scan technique, the nonlinear optical properties and the excited state absorption cross-sections were determined by fitting the Z-scan data. The k value was the highest for Pb derivative at 211, making it the best nonlinear optical material. In terms of hyperpolarizability, Pb derivative (containing a larger central metal) also gave the largest value followed by aluminum derivative (containing a small central metal). The distortion of the ring caused by the central metal is used to explain the hyperpolarizability values. Large nonlinear absorption coefficient values, βeff, in the range of 3.558–4.763 × 10-9 cm.W-1 and low saturation fluence values, Fsat between 21.5–38.5 mJ.cm-2, were obtained for these samples.
- Full Text:
- Date Issued: 2013