Characterization and application of phthalocyanine-gold nanoparticle conjugates
- Authors: Tombe, Sekai Lana
- Date: 2013
- Subjects: Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4293 , http://hdl.handle.net/10962/d1004517 , Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Description: This work presents the syntheses, photophysical and photochemical characterization of arylthio zinc phthalocyanines and their gold nanoparticle conjugates. Spectroscopic and microscopic studies confirmed the formation of the phthalocyanine-gold nanoparticle conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines. The studies showed that the presence of gold nanoparticles significantly lowered fluorescence quantum yields and lifetimes. However, this interaction did not restrict the formation of excited singlet and triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and therefore enhanced photocatalytic activity compared to the phthalocyanines. The zinc phthalocyanines and their gold nanoparticle conjugates were successfully incorporated into electrospun polymer fibers. Spectral characteristics of the functionalized electrospun fibers indicated that the phthalocyanines and phthalocyanine-gold nanoparticle conjugates were bound and their integrity was maintained within the polymeric fiber matrices. The photophysical and photochemical properties of the complexes were equally maintained within the electrospun fibers. The functionalized fibers were applied for the photoconversion of 4-chlorophenol and Orange G as model organic pollutants. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Authors: Tombe, Sekai Lana
- Date: 2013
- Subjects: Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4293 , http://hdl.handle.net/10962/d1004517 , Phthalocyanines , Gold , Zinc , Nanoparticles , Bioconjugates , Photochemistry , Photocatalysis , Electrospinning , Polymers , Pollutants , Phenols , Azo dyes
- Description: This work presents the syntheses, photophysical and photochemical characterization of arylthio zinc phthalocyanines and their gold nanoparticle conjugates. Spectroscopic and microscopic studies confirmed the formation of the phthalocyanine-gold nanoparticle conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines. The studies showed that the presence of gold nanoparticles significantly lowered fluorescence quantum yields and lifetimes. However, this interaction did not restrict the formation of excited singlet and triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and therefore enhanced photocatalytic activity compared to the phthalocyanines. The zinc phthalocyanines and their gold nanoparticle conjugates were successfully incorporated into electrospun polymer fibers. Spectral characteristics of the functionalized electrospun fibers indicated that the phthalocyanines and phthalocyanine-gold nanoparticle conjugates were bound and their integrity was maintained within the polymeric fiber matrices. The photophysical and photochemical properties of the complexes were equally maintained within the electrospun fibers. The functionalized fibers were applied for the photoconversion of 4-chlorophenol and Orange G as model organic pollutants. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
Electrocatalytic detection of pesticides with electrodes modified with nanoparticles of phthalocyanines and multiwalled carbon nanotubes
- Authors: Siswana, Msimelelo Patrick
- Date: 2013
- Subjects: Phthalocyanines Pesticides Electrocatalysis Electrochemistry Nanotubes Nanoparticles Transmission electron microscopy Scanning electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4282 , http://hdl.handle.net/10962/d1002613
- Description: Three types of electrodes: carbon paste electrodes modified with nanoparticles of metallophthalocyanines (MPcNP-CPEs, M = Mn, Fe, Ni, Co), basal plane pyrolytic graphite electrodes modified with iron or nickel phthalocyanine nanoparticles and multiwalled carbon nanotube composites (FePcNP/MWCNT-BPPGE or NiPcNP/MWCNT-BPPGE),and basal plane pyrolytic graphite electrodes modified with multiwalled carbon nanotubes and electropolymerized metal tetra-aminophthalocyanines (poly-MTAPc-MWCNT-BPPGE), where M is Mn, Fe, Ni or Co, were prepared. Electrochemical characterizations showed that faster electron transfer kinetics occurred at the NiPcNP/MWCNT-BPPGE than at the FePcNP/MWCNT-BPPGE surface. SEM and electrochemical characterizations of poly-MTAPc-MWCNT-BPPGE showed that MTAPc had been deposited on the MWCNTBPPGE surface, and that the poly-CoTAPc-MWCNT-BPPGE exhibited the fastest electron transfer kinetics of all the poly-MTAPc-MWCNT-BPPGEs. Using amitrole and asulam as test analytes, electrochemical experiments showed that, amongst the CPEs, the FePcNP-CPE and NiPcNP-CPE displayed the most electrocatalytic behavior towards amitrole and asulam oxidation, respectively, and further experiments were done to obtain the electrochemical parameters associated with these electrodes and the corresponding analytes. Although, the FePcNP/MWCNT- BPPGE displayed electrocatalytic behavior towards amitrole oxidation in comparison with the bare BPPGE, it was less electrocatalytic than the FePcNP-CPE in terms of detection potential. The NiPcNP/MWCNT-BPPGE displayed the same detection potential as the NiPcNP-CPE. The poly-FeTAPc-MWCNT-BPPGE exhibited the most electrocatalytic behavior towards amitrole, of all the electrodes investigated, and the poly-CoTAPc-MWCNT-BPPGE displayed the best electrocatalytic behavior towards asulam, amongst the poly-MTAPc-MWCNT-BPPGEs.
- Full Text:
- Authors: Siswana, Msimelelo Patrick
- Date: 2013
- Subjects: Phthalocyanines Pesticides Electrocatalysis Electrochemistry Nanotubes Nanoparticles Transmission electron microscopy Scanning electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4282 , http://hdl.handle.net/10962/d1002613
- Description: Three types of electrodes: carbon paste electrodes modified with nanoparticles of metallophthalocyanines (MPcNP-CPEs, M = Mn, Fe, Ni, Co), basal plane pyrolytic graphite electrodes modified with iron or nickel phthalocyanine nanoparticles and multiwalled carbon nanotube composites (FePcNP/MWCNT-BPPGE or NiPcNP/MWCNT-BPPGE),and basal plane pyrolytic graphite electrodes modified with multiwalled carbon nanotubes and electropolymerized metal tetra-aminophthalocyanines (poly-MTAPc-MWCNT-BPPGE), where M is Mn, Fe, Ni or Co, were prepared. Electrochemical characterizations showed that faster electron transfer kinetics occurred at the NiPcNP/MWCNT-BPPGE than at the FePcNP/MWCNT-BPPGE surface. SEM and electrochemical characterizations of poly-MTAPc-MWCNT-BPPGE showed that MTAPc had been deposited on the MWCNTBPPGE surface, and that the poly-CoTAPc-MWCNT-BPPGE exhibited the fastest electron transfer kinetics of all the poly-MTAPc-MWCNT-BPPGEs. Using amitrole and asulam as test analytes, electrochemical experiments showed that, amongst the CPEs, the FePcNP-CPE and NiPcNP-CPE displayed the most electrocatalytic behavior towards amitrole and asulam oxidation, respectively, and further experiments were done to obtain the electrochemical parameters associated with these electrodes and the corresponding analytes. Although, the FePcNP/MWCNT- BPPGE displayed electrocatalytic behavior towards amitrole oxidation in comparison with the bare BPPGE, it was less electrocatalytic than the FePcNP-CPE in terms of detection potential. The NiPcNP/MWCNT-BPPGE displayed the same detection potential as the NiPcNP-CPE. The poly-FeTAPc-MWCNT-BPPGE exhibited the most electrocatalytic behavior towards amitrole, of all the electrodes investigated, and the poly-CoTAPc-MWCNT-BPPGE displayed the best electrocatalytic behavior towards asulam, amongst the poly-MTAPc-MWCNT-BPPGEs.
- Full Text:
Low symmetry metallophthalocyanines and their nanoparticle conjugates for photodynamic antimicrobial chemotherapy
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
- Full Text:
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
- Full Text:
Photophysical properties of zinc carboxy phthalocyanine-quantum dot conjugates
- Authors: Sekhosana, Kutloano Edward
- Date: 2013 , 2013-03-27
- Subjects: Phthalocyanines , Quantum dots , Zinc , Photochemistry , Atomic force microscopy , Transmission electron microscopy , Raman spectroscopy , Infrared spectroscopy , X-ray photoelectron spectroscopy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4276 , http://hdl.handle.net/10962/d1001652 , Phthalocyanines , Quantum dots , Zinc , Photochemistry , Atomic force microscopy , Transmission electron microscopy , Raman spectroscopy , Infrared spectroscopy , X-ray photoelectron spectroscopy
- Description: This thesis presents work based on the interactions of water soluble caboxylated zinc phthalocyanines (Pcs) and coreshell quantum dots (QDs). The Pcs are ZnPc(COOH)₈ and ZnPc(COOH)₄ and coreshell QDs are CdTe@ZnS-GSH. GSH = L-glutathione. Characterization and photophysical studies of conjugates were carried out. The approach of coordinating Pcs to QDs was achieved using an organic cross linker, N-N’-dicyclohexylcarbodiimide (DCC) at pH 10 at room temperature. Employing atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, infrared and X-ray photoelectron spectroscopies, the formation of the conjugates was confirmed. Upon conjugation with Pc derivatives, the fluorescence quantum yield of CdTe@ZnS-GSH decreased due to energy transfer from the QDs to the Pc. The average fluorescence lifetime of the CdTe@ZnS-GSH QD also decreased upon conjugation. The föster resonance energy transfer (FRET) behaviour of CdTe@ZnS-GSH-ZnPc(COOH)₄ conjugates was compared to that of CdTe@ZnS-GSH-ZnPc(COOH)₈. Higher FRET efficiencies were observed for CdTe@ZnS-GSH-ZnPc(COOH)₄-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₄-linked compared to the corresponding CdTe@ZnS-GSH-ZnPc(COOH)₈-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₈-linked. Triplet quantum yield (ΦT) and lifetime (ΤT) of ZnPc(COOH)₈ were found to increase in the presence of coreshell QDs. Though the singlet quantum yield (ΦΔ) value of ZnPc(COOH)8 was lower than ΦT , there was a slight upsurge in the ΦT in the presence of QDs. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Authors: Sekhosana, Kutloano Edward
- Date: 2013 , 2013-03-27
- Subjects: Phthalocyanines , Quantum dots , Zinc , Photochemistry , Atomic force microscopy , Transmission electron microscopy , Raman spectroscopy , Infrared spectroscopy , X-ray photoelectron spectroscopy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4276 , http://hdl.handle.net/10962/d1001652 , Phthalocyanines , Quantum dots , Zinc , Photochemistry , Atomic force microscopy , Transmission electron microscopy , Raman spectroscopy , Infrared spectroscopy , X-ray photoelectron spectroscopy
- Description: This thesis presents work based on the interactions of water soluble caboxylated zinc phthalocyanines (Pcs) and coreshell quantum dots (QDs). The Pcs are ZnPc(COOH)₈ and ZnPc(COOH)₄ and coreshell QDs are CdTe@ZnS-GSH. GSH = L-glutathione. Characterization and photophysical studies of conjugates were carried out. The approach of coordinating Pcs to QDs was achieved using an organic cross linker, N-N’-dicyclohexylcarbodiimide (DCC) at pH 10 at room temperature. Employing atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, infrared and X-ray photoelectron spectroscopies, the formation of the conjugates was confirmed. Upon conjugation with Pc derivatives, the fluorescence quantum yield of CdTe@ZnS-GSH decreased due to energy transfer from the QDs to the Pc. The average fluorescence lifetime of the CdTe@ZnS-GSH QD also decreased upon conjugation. The föster resonance energy transfer (FRET) behaviour of CdTe@ZnS-GSH-ZnPc(COOH)₄ conjugates was compared to that of CdTe@ZnS-GSH-ZnPc(COOH)₈. Higher FRET efficiencies were observed for CdTe@ZnS-GSH-ZnPc(COOH)₄-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₄-linked compared to the corresponding CdTe@ZnS-GSH-ZnPc(COOH)₈-mixed or CdTe@ZnS-GSH-ZnPc(COOH)₈-linked. Triplet quantum yield (ΦT) and lifetime (ΤT) of ZnPc(COOH)₈ were found to increase in the presence of coreshell QDs. Though the singlet quantum yield (ΦΔ) value of ZnPc(COOH)8 was lower than ΦT , there was a slight upsurge in the ΦT in the presence of QDs. , Microsoft� Word 2010 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
Photophysicochemical and photodynamic antimicrobial chemotherapeutic studies of novel phthalocyanines conjugated to silver nanoparticles
- Authors: Rapulenyane, Nomasonto
- Date: 2013 , 2013-06-10
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4291 , http://hdl.handle.net/10962/d1003912 , Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Description: This work reports on the synthesis, characterization and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines: namely tris{11,19, 27-(1,2- diethylaminoethylthiol)-2-(captopril) phthalocyanine Zn ((ZnMCapPc (1.5)), hexakis{8,11,16,19,42,27-(octylthio)-1-(4-phenoxycarboxy) phthalocyanine} Zn (ZnMPCPc(1.7)) and Tris {11, 19, 27-(1,2-diethylaminoethylthiol)-1,2(caffeic acid) phthalocyanine} Zn ((ZnMCafPc (1.3)). Symmetrically substituted counterparts (tetrakis(diethylamino)zinc phthalocyaninato (3.8), octakis(octylthio)zinc phthalocyaninato (3.9) and tetrakis (carboxyphenoxy)zinc phthalocyaninato (3.10) complexes) were also synthesized for comparison of the photophysicochemical properties and to investigate the effect of the substituents on the low symmetry Pcs. The complexes were successfully characterized by IR, NMR, mass spectral and elemental analyses. All the complexes showed the ability to produce singlet oxygen, while the highest triplet quantum yields were obtained for 1.7, 1.5 and 3.9 (0.80, 0.65 and 0.62 respectively and the lowest were obtained for 1.3 and 3.10 (0.57 and 0.47 respectively). High triplet lifetimes (109-286 μs) were also obtained for all complexes, with 1.7 being the highest (286 μs) which also corresponds to its triplet and singlet quantum yields (0.80 and 0.77 respectively). The photosensitizing properties of low symmetry derivatives, ZnMCapPc and ZnMCafPc were investigated by conjugating glutathione (GSH) capped silver nanoparticles (AgNP). The formation of the amide bond was confirmed by IR and UV-Vis spectroscopies. The photophysicochemical behaviour of the novel phthalocyanine-GSH-AgNP conjugates and the simple mixture of the Ag NPs with low the symmetry phthalocyanines were investigated. It was observed that upon conjugation of the phthalocyanines to the GSH-AgNPs, a blue shift in the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines (Pc) alone. Complex 1.5 triplet lifetimes increased from 109 to 148 and triplet quantum yield from 0.65 to 0.86 upon conjugation. Fluorescence lifetimes and quantum yields decreased for the conjugates compared to the phthalocyanines alone, due to the quenching caused by the Ag NPs. The antimicrobial activity of the zinc phthalocyanines (complexes 1.3 and 1.5) and their conjugates against Escherichia coli was investigated. Only 1.3 and 1.5 complexes were investigated because of the availability of the sample. In general phthalocyanines showed increase in antibacterial activity with the increase in phthalocyanines concentration in the presence and absence of light. The Pc complexes and their Ag NP conjugates showed an increase in antibacterial activity, due to the synergistic effect afforded by Ag NP and Pcs. Improved antibacterial properties were obtained upon irradiation. 1.5-AgNPs had the highest antibacterial activity compared to 1.3-AgNPs conjugate; these results are in agreement with the photophysical behaviour. This work demonstrates improved photophysicochemical properties of low symm
- Full Text:
- Authors: Rapulenyane, Nomasonto
- Date: 2013 , 2013-06-10
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4291 , http://hdl.handle.net/10962/d1003912 , Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Description: This work reports on the synthesis, characterization and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines: namely tris{11,19, 27-(1,2- diethylaminoethylthiol)-2-(captopril) phthalocyanine Zn ((ZnMCapPc (1.5)), hexakis{8,11,16,19,42,27-(octylthio)-1-(4-phenoxycarboxy) phthalocyanine} Zn (ZnMPCPc(1.7)) and Tris {11, 19, 27-(1,2-diethylaminoethylthiol)-1,2(caffeic acid) phthalocyanine} Zn ((ZnMCafPc (1.3)). Symmetrically substituted counterparts (tetrakis(diethylamino)zinc phthalocyaninato (3.8), octakis(octylthio)zinc phthalocyaninato (3.9) and tetrakis (carboxyphenoxy)zinc phthalocyaninato (3.10) complexes) were also synthesized for comparison of the photophysicochemical properties and to investigate the effect of the substituents on the low symmetry Pcs. The complexes were successfully characterized by IR, NMR, mass spectral and elemental analyses. All the complexes showed the ability to produce singlet oxygen, while the highest triplet quantum yields were obtained for 1.7, 1.5 and 3.9 (0.80, 0.65 and 0.62 respectively and the lowest were obtained for 1.3 and 3.10 (0.57 and 0.47 respectively). High triplet lifetimes (109-286 μs) were also obtained for all complexes, with 1.7 being the highest (286 μs) which also corresponds to its triplet and singlet quantum yields (0.80 and 0.77 respectively). The photosensitizing properties of low symmetry derivatives, ZnMCapPc and ZnMCafPc were investigated by conjugating glutathione (GSH) capped silver nanoparticles (AgNP). The formation of the amide bond was confirmed by IR and UV-Vis spectroscopies. The photophysicochemical behaviour of the novel phthalocyanine-GSH-AgNP conjugates and the simple mixture of the Ag NPs with low the symmetry phthalocyanines were investigated. It was observed that upon conjugation of the phthalocyanines to the GSH-AgNPs, a blue shift in the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines (Pc) alone. Complex 1.5 triplet lifetimes increased from 109 to 148 and triplet quantum yield from 0.65 to 0.86 upon conjugation. Fluorescence lifetimes and quantum yields decreased for the conjugates compared to the phthalocyanines alone, due to the quenching caused by the Ag NPs. The antimicrobial activity of the zinc phthalocyanines (complexes 1.3 and 1.5) and their conjugates against Escherichia coli was investigated. Only 1.3 and 1.5 complexes were investigated because of the availability of the sample. In general phthalocyanines showed increase in antibacterial activity with the increase in phthalocyanines concentration in the presence and absence of light. The Pc complexes and their Ag NP conjugates showed an increase in antibacterial activity, due to the synergistic effect afforded by Ag NP and Pcs. Improved antibacterial properties were obtained upon irradiation. 1.5-AgNPs had the highest antibacterial activity compared to 1.3-AgNPs conjugate; these results are in agreement with the photophysical behaviour. This work demonstrates improved photophysicochemical properties of low symm
- Full Text:
Photophysicochemical properties of aluminium phthalocyanine-platinum conjugates
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
Phototransformation of pollutants using lutetium and zinc phthalocyanines anchored on electrospun polymer fibers
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
Electrochemical sensing and immunosensing using metallophthalocyanines and biomolecular modified surfaces
- Authors: Mashazi, Philani Nkosinathi
- Date: 2012
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Measles -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5580 , http://hdl.handle.net/10962/d1018248
- Description: The synthesis of cobalt and manganese phthalocyanine complexes bearing eight hexylthio and four amino substituents was carried out. The formation of thin films of these complexes using different modification methods was also studied. Hexylthio functionalized metallophthalocyanine complexes were immobilized onto gold electrode surfaces using the self-assembly techniques. Surface modifications using cobalt and manganese tetraamino phthalocyanine as polymers, monolayers (onto electrografted surfaces) and as carbon nanotube – metallophthalocyanine conjugates was also carried out. The new method of modifying gold electrodes with metal tetraamino phthalocyanine complexes was investigated. The modified electrode surfaces were studied for their electrocatalytic properties and as potential electrochemical sensors for the detection of hydrogen peroxide (H₂O₂). The limits of detection for the H₂O₂ were of the orders of ~10⁻⁷ M for all the modified electrodes. The modified electrodes gave very good analytical parameters; such as good sensitivity, linearity at studied concentration range and well-defined analytical peaks with increased current densities. The modification methods were reproducible, highly conducting thin films were formed and the modified electrodes were very stable. The design of electrochemical immunosensors for the detection of measles-specific antibodies was also carried out. The modified surface with measles-antigen as sensing element was accomplished using covalent immobilization for an intimate connection of the measles-antigen as a sensing layer onto an electrode surface. Two methods of detecting measles-specific antibodies were investigated and these methods were based on electrochemical impedance, i.e. label-free detection, and voltammetric method using horse-radish peroxidase (HRP) labeled antibody as a reporter. The detection of measles-specific antibodies was accomplished using both these methods. The potential applications of the designed immunosensor were evaluated in real samples (human and newborn calf serum) and the electrodes could detect the antibodies in the complex sample matrix with ease.
- Full Text:
- Authors: Mashazi, Philani Nkosinathi
- Date: 2012
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Measles -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5580 , http://hdl.handle.net/10962/d1018248
- Description: The synthesis of cobalt and manganese phthalocyanine complexes bearing eight hexylthio and four amino substituents was carried out. The formation of thin films of these complexes using different modification methods was also studied. Hexylthio functionalized metallophthalocyanine complexes were immobilized onto gold electrode surfaces using the self-assembly techniques. Surface modifications using cobalt and manganese tetraamino phthalocyanine as polymers, monolayers (onto electrografted surfaces) and as carbon nanotube – metallophthalocyanine conjugates was also carried out. The new method of modifying gold electrodes with metal tetraamino phthalocyanine complexes was investigated. The modified electrode surfaces were studied for their electrocatalytic properties and as potential electrochemical sensors for the detection of hydrogen peroxide (H₂O₂). The limits of detection for the H₂O₂ were of the orders of ~10⁻⁷ M for all the modified electrodes. The modified electrodes gave very good analytical parameters; such as good sensitivity, linearity at studied concentration range and well-defined analytical peaks with increased current densities. The modification methods were reproducible, highly conducting thin films were formed and the modified electrodes were very stable. The design of electrochemical immunosensors for the detection of measles-specific antibodies was also carried out. The modified surface with measles-antigen as sensing element was accomplished using covalent immobilization for an intimate connection of the measles-antigen as a sensing layer onto an electrode surface. Two methods of detecting measles-specific antibodies were investigated and these methods were based on electrochemical impedance, i.e. label-free detection, and voltammetric method using horse-radish peroxidase (HRP) labeled antibody as a reporter. The detection of measles-specific antibodies was accomplished using both these methods. The potential applications of the designed immunosensor were evaluated in real samples (human and newborn calf serum) and the electrodes could detect the antibodies in the complex sample matrix with ease.
- Full Text:
Electrochemistry and photophysicochemical studies of titanium, tantalum and vanadium phthalocyanines in the presence of nanomaterials
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
Nanocomposites of nickel phthalocyanines as electrocatalysts for the oxidation of chlorophenols an experimental and theoretical approach
- Authors: Khene, Mielie Samson
- Date: 2012
- Subjects: Nanocomposites (Materials) -- Research Phthalocyanines -- Research Chlorophenols -- Research Electrocatalysis -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4326 , http://hdl.handle.net/10962/d1004986
- Description: In this work the interaction between peripherally (b) substituted nickel tetrahydroxyphthalocyanines (b-NiPc(OH)4 and poly-b-Ni(O)Pc(OH)4) with 4-chlorophenol is theoretically rationalized by performing calculations at the B3LYP/6-31G(d) level. Density functional theory (DFT) and molecular orbital theory are used to calculate the condensed Fukui function for phthalocyanine derivatives and 4-chlorophenol, in order to determine the reactive sites involved when 4-chlorophenol is oxidized, and to compare theoretically predicted reactivity to experimentally determined electrocatalytic activity. Electrocatalytic activities of adsorbed NiPc derivatives: OPGE-α-NiPc(OH)8 (OPGE = ordinary pyrolytic graphite electrode, α = nonperipheral substitution), OPGE-a-NiPc(OH)4 and OPGE-β- NiPc(OH)4 are compared with those of the polymerized counterparts: OPGE-poly-α-Ni(O)Pc(OH)8, OPGE poly-a-NiPc(OH)4 and OPGE-poly-β-NiPc(OH)4, respectively. β-NiPc(NH2)4, β-NiPc(OH)4, α-NiPc(OH)4, α-NiPc(OH)8, α-NiPc(C10H21)8 are adsorbed on singled walled carbon nanotube (SWCNT) and β-NiPc(NH2)4-SWCNT (linked to SWCNT), are used to modify glassy carbon electrode (GCE) and employed for the electro oxidation of chlorophenols. The β-NiPc(NH2)4-SWCNT gave the best current response for the oxidation of 4-chlorophenol. α-NiPc(OH)8-SWCNT and α-NiPc(C10H21)8 gave the best resistance to electrode fouling due to oxidation by product of 4-chlorophenol. The synthesis of conjugates of cadmium telluride quantum dots (CdTe-QDs) capped with thioglycolic acid and peripherally substituted nickel tetraamino phthalocyanine (β-NiPc(NH2)4) complex were also employed for the oxidation of chlorophenols. Separation of one of the diastereomers of 1, 2-subnaphthalocyanine (SubNPc) was achieved as well as separation of the enantiomers. The absorption and magnetic circular dichroism spectra, together with theoretical calculations, reveal rather small variations in the frontier molecular orbitals of the SubNPc compared to conventional subphthalocyanine (SubPc), except for the destabilization of the highest occupied molecular orbital (HOMO), which results in a characteristic absorption in the Soret band region. The chirality of SubNPc, including the cyclic dichroism (CD) signs and intensities, are discussed in detail.
- Full Text:
- Authors: Khene, Mielie Samson
- Date: 2012
- Subjects: Nanocomposites (Materials) -- Research Phthalocyanines -- Research Chlorophenols -- Research Electrocatalysis -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4326 , http://hdl.handle.net/10962/d1004986
- Description: In this work the interaction between peripherally (b) substituted nickel tetrahydroxyphthalocyanines (b-NiPc(OH)4 and poly-b-Ni(O)Pc(OH)4) with 4-chlorophenol is theoretically rationalized by performing calculations at the B3LYP/6-31G(d) level. Density functional theory (DFT) and molecular orbital theory are used to calculate the condensed Fukui function for phthalocyanine derivatives and 4-chlorophenol, in order to determine the reactive sites involved when 4-chlorophenol is oxidized, and to compare theoretically predicted reactivity to experimentally determined electrocatalytic activity. Electrocatalytic activities of adsorbed NiPc derivatives: OPGE-α-NiPc(OH)8 (OPGE = ordinary pyrolytic graphite electrode, α = nonperipheral substitution), OPGE-a-NiPc(OH)4 and OPGE-β- NiPc(OH)4 are compared with those of the polymerized counterparts: OPGE-poly-α-Ni(O)Pc(OH)8, OPGE poly-a-NiPc(OH)4 and OPGE-poly-β-NiPc(OH)4, respectively. β-NiPc(NH2)4, β-NiPc(OH)4, α-NiPc(OH)4, α-NiPc(OH)8, α-NiPc(C10H21)8 are adsorbed on singled walled carbon nanotube (SWCNT) and β-NiPc(NH2)4-SWCNT (linked to SWCNT), are used to modify glassy carbon electrode (GCE) and employed for the electro oxidation of chlorophenols. The β-NiPc(NH2)4-SWCNT gave the best current response for the oxidation of 4-chlorophenol. α-NiPc(OH)8-SWCNT and α-NiPc(C10H21)8 gave the best resistance to electrode fouling due to oxidation by product of 4-chlorophenol. The synthesis of conjugates of cadmium telluride quantum dots (CdTe-QDs) capped with thioglycolic acid and peripherally substituted nickel tetraamino phthalocyanine (β-NiPc(NH2)4) complex were also employed for the oxidation of chlorophenols. Separation of one of the diastereomers of 1, 2-subnaphthalocyanine (SubNPc) was achieved as well as separation of the enantiomers. The absorption and magnetic circular dichroism spectra, together with theoretical calculations, reveal rather small variations in the frontier molecular orbitals of the SubNPc compared to conventional subphthalocyanine (SubPc), except for the destabilization of the highest occupied molecular orbital (HOMO), which results in a characteristic absorption in the Soret band region. The chirality of SubNPc, including the cyclic dichroism (CD) signs and intensities, are discussed in detail.
- Full Text:
Photophysicochemical and photodynamic studies of phthalocyanines conjugated to selected drug delivery agents
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
Photophysicochemical studies of phenylthio phthalocyanines interaction with gold nanoparticles and applications in dye sensitised solar cells and optical limiting
- Authors: Forteath, Shaun
- Date: 2012
- Subjects: Phthalocyanines , Nanoparticles , Photochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4334 , http://hdl.handle.net/10962/d1004995 , Phthalocyanines , Nanoparticles , Photochemistry
- Description: The syntheses, spectroscopic characterisation, photophysical and photochemical studies have been conducted for a variety of phenylthio substituted phthalocyanines (Pcs). Comparisons have been made taking into consideration the influence of the central metal ion, solvent properties and substituent type. The optical limiting properties were also determined for all the Pcs synthesised. A low-symmetry metallophthalocyanine complex was similarly characterised and the photoelectrochemical parameters determined when used as a sensitiser of nanoporous ZnO. The symmetric analogue was conjugated to gold nanoparticles to determine the influence of interactions on its photophysical properties and distinct differences occurred in the absorption and fluorescence spectra suggesting successful formation of conjugates.
- Full Text:
- Authors: Forteath, Shaun
- Date: 2012
- Subjects: Phthalocyanines , Nanoparticles , Photochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4334 , http://hdl.handle.net/10962/d1004995 , Phthalocyanines , Nanoparticles , Photochemistry
- Description: The syntheses, spectroscopic characterisation, photophysical and photochemical studies have been conducted for a variety of phenylthio substituted phthalocyanines (Pcs). Comparisons have been made taking into consideration the influence of the central metal ion, solvent properties and substituent type. The optical limiting properties were also determined for all the Pcs synthesised. A low-symmetry metallophthalocyanine complex was similarly characterised and the photoelectrochemical parameters determined when used as a sensitiser of nanoporous ZnO. The symmetric analogue was conjugated to gold nanoparticles to determine the influence of interactions on its photophysical properties and distinct differences occurred in the absorption and fluorescence spectra suggesting successful formation of conjugates.
- Full Text:
Characterization and electrocatalytic applications of metallophthalocyanine-single walled carbon nanotube conjugates
- Authors: Mugadza, Tawanda
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Pesticides Nanotubes Electrocatalysis Electrochemistry Transmission electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4419 , http://hdl.handle.net/10962/d1006855
- Description: Metallophthalocyanine-single walled carbon nanotube conjugates were successfully synthesized and applied in the electrochemical characterizations of pesticides (amitrole and diuron) and 2-mercaptoethanol (2-ME). The formation of conjugates was confirmed through the use of the following analytical techniques: UV-vis, FTIR, Raman and XRD spectroscopies, atomic force and transmission electron microscopies and voltammetry. Chemically linking SWCNT to MPcs created platforms that offered efficient transfer of electrons and this was confirmed through electrochemical impedance studies (EIS) and voltammetry as shown by lower ΔEp values observed in conjugates. Carboxy carrying MPcs have very poor electron transfer kinetics (both tetrasubstituted and low symmetry), but the presence of SWCNTs activates their catalysis. All electrochemical studies were done at pH 4. Cyclic voltammetry, rotating disk linear sweep voltammetry, chronoamperometry and EIS were used in the electrochemical characterization of 2-ME and the pesticides on poly-Ni(OH)TAPc and MPc-SWCNT modified glassy carbon electrodes (GCEs). High Tafel slopes were observed for the pesticides relative to 2-ME, an indication of the passivating nature of their oxidation products. However, conjugates showed very high resistances to passivation and were easily regenerated by shaking in methanol. Improved catalysis of the conjugates is also indicated by the high catalytic rate constants for the analytes, observed on these electrodes. Conjugates of low symmetry MPcs with SWCNTs gave the highest catalytic rate constants, confirming better catalysis on these electrode surfaces. The nature of SWCNT functionalization also affected catalysis, with amine functionalized SWCNTs inducing better catalytic properties into the MPcs than carboxylic acid terminated CNTs. The presence of amine functionalized SWCNTs activates the catalysis of non-catalytic carboxy-carrying MPcs and this is more pronounced in conjugates of tetrasubstituted MPcs relative to those of low symmetry Pcs. Ethylene amine (EA) functionalized SWCNTs reduced redox overpotentials of the MPcs more than the phenyl-amine (PA) functionalized counterparts. Poly-NiTAPc was successfully converted to poly-Ni(OH)TAPc through cyclisation in pH 4 buffer and showed very good catalytic properties towards diuron, relative to the former.
- Full Text:
- Authors: Mugadza, Tawanda
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Pesticides Nanotubes Electrocatalysis Electrochemistry Transmission electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4419 , http://hdl.handle.net/10962/d1006855
- Description: Metallophthalocyanine-single walled carbon nanotube conjugates were successfully synthesized and applied in the electrochemical characterizations of pesticides (amitrole and diuron) and 2-mercaptoethanol (2-ME). The formation of conjugates was confirmed through the use of the following analytical techniques: UV-vis, FTIR, Raman and XRD spectroscopies, atomic force and transmission electron microscopies and voltammetry. Chemically linking SWCNT to MPcs created platforms that offered efficient transfer of electrons and this was confirmed through electrochemical impedance studies (EIS) and voltammetry as shown by lower ΔEp values observed in conjugates. Carboxy carrying MPcs have very poor electron transfer kinetics (both tetrasubstituted and low symmetry), but the presence of SWCNTs activates their catalysis. All electrochemical studies were done at pH 4. Cyclic voltammetry, rotating disk linear sweep voltammetry, chronoamperometry and EIS were used in the electrochemical characterization of 2-ME and the pesticides on poly-Ni(OH)TAPc and MPc-SWCNT modified glassy carbon electrodes (GCEs). High Tafel slopes were observed for the pesticides relative to 2-ME, an indication of the passivating nature of their oxidation products. However, conjugates showed very high resistances to passivation and were easily regenerated by shaking in methanol. Improved catalysis of the conjugates is also indicated by the high catalytic rate constants for the analytes, observed on these electrodes. Conjugates of low symmetry MPcs with SWCNTs gave the highest catalytic rate constants, confirming better catalysis on these electrode surfaces. The nature of SWCNT functionalization also affected catalysis, with amine functionalized SWCNTs inducing better catalytic properties into the MPcs than carboxylic acid terminated CNTs. The presence of amine functionalized SWCNTs activates the catalysis of non-catalytic carboxy-carrying MPcs and this is more pronounced in conjugates of tetrasubstituted MPcs relative to those of low symmetry Pcs. Ethylene amine (EA) functionalized SWCNTs reduced redox overpotentials of the MPcs more than the phenyl-amine (PA) functionalized counterparts. Poly-NiTAPc was successfully converted to poly-Ni(OH)TAPc through cyclisation in pH 4 buffer and showed very good catalytic properties towards diuron, relative to the former.
- Full Text:
Effect of nanoparticles on the photophysicochemical behaviour of metallophthalocyanines
- Moeno, Sharon Keitumetse Gail Mpheletso
- Authors: Moeno, Sharon Keitumetse Gail Mpheletso
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Nanoparticles Photochemistry Quantum dots
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4310 , http://hdl.handle.net/10962/d1004968
- Description: The synthesis, spectroscopic characterization, and studies of the photophysicochemical behaviour of selective anionic, cationic and neutral metallophthallocyanine (MPc) complexes were carried out and the results are presented herein. Studies on the effect of the central metal ion, the solvent used and the presence of nanoparticles on the photophysicochemical properties were conducted. The findings showed that the photophysicochemical parameters were mostly enhanced in the presence of central metal ions of high atomic numbers and also in the presence of nanoparticles. It was also observed that solvents that encouraged the monomericity of the MPc complexes also lead to improved photophysical and photochemical behaviour. CdTe quantum dots (QDs) stabilized with mercaptocarbonic acids were also observed to cause stimulated emission of the MPcs through Förster resonance energy transfer (FRET) thus acting as energy donors while the respective MPc acted as energy acceptors in all the FRET studies. FRET was observed following the photoexcitation of QDs for all monomeric anionic MPcs but it was also shown to occur for some cationic MPcs in organic media. Both the substituent and solvent used were found to exert a strong influence on the occurrence of FRET. Other cationic MPcs however showed different behaviour in the presence of the meraptocarbonic stabilized CdTe QDs; with the cationic porphyrazine giving clear indications of Pc ring reduction. The rest of the cationic MPcs did not give clear evidence of Pc ring reduction, instead they showed signs of aggregate formation possibly from the assembly of electrostatic ion pair complexes which could result in reduction of the quaternized pyridinium ring of the substituent. Both the QDs and the MPc complex emission spectra were significantly quenched for each in the presence of the other. Stern-Volmer quenching studies indicated that both static and dynamic quenching of the QDs in the presence of MPcs took place. The fluorescence lifetimes of the mercaptopropionic acid (MPA) capped CdTe QDs in the presence of various MPc complexes showed quenching of mostly the longer lifetimes of the QDs in the presence of MPcs suggesting that the surface defects and states are involved in the interaction of the QDs and MPcs. An MPc complex terminating in thio tethers was employed in the conjugation to AuNPs. Spectroscopic and microscopic studies confirmed the formation of the MPc-AuNP conjugate which was also shown to exhibit improved photophysicochemical properties compared to the free MPc.
- Full Text:
- Authors: Moeno, Sharon Keitumetse Gail Mpheletso
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Nanoparticles Photochemistry Quantum dots
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4310 , http://hdl.handle.net/10962/d1004968
- Description: The synthesis, spectroscopic characterization, and studies of the photophysicochemical behaviour of selective anionic, cationic and neutral metallophthallocyanine (MPc) complexes were carried out and the results are presented herein. Studies on the effect of the central metal ion, the solvent used and the presence of nanoparticles on the photophysicochemical properties were conducted. The findings showed that the photophysicochemical parameters were mostly enhanced in the presence of central metal ions of high atomic numbers and also in the presence of nanoparticles. It was also observed that solvents that encouraged the monomericity of the MPc complexes also lead to improved photophysical and photochemical behaviour. CdTe quantum dots (QDs) stabilized with mercaptocarbonic acids were also observed to cause stimulated emission of the MPcs through Förster resonance energy transfer (FRET) thus acting as energy donors while the respective MPc acted as energy acceptors in all the FRET studies. FRET was observed following the photoexcitation of QDs for all monomeric anionic MPcs but it was also shown to occur for some cationic MPcs in organic media. Both the substituent and solvent used were found to exert a strong influence on the occurrence of FRET. Other cationic MPcs however showed different behaviour in the presence of the meraptocarbonic stabilized CdTe QDs; with the cationic porphyrazine giving clear indications of Pc ring reduction. The rest of the cationic MPcs did not give clear evidence of Pc ring reduction, instead they showed signs of aggregate formation possibly from the assembly of electrostatic ion pair complexes which could result in reduction of the quaternized pyridinium ring of the substituent. Both the QDs and the MPc complex emission spectra were significantly quenched for each in the presence of the other. Stern-Volmer quenching studies indicated that both static and dynamic quenching of the QDs in the presence of MPcs took place. The fluorescence lifetimes of the mercaptopropionic acid (MPA) capped CdTe QDs in the presence of various MPc complexes showed quenching of mostly the longer lifetimes of the QDs in the presence of MPcs suggesting that the surface defects and states are involved in the interaction of the QDs and MPcs. An MPc complex terminating in thio tethers was employed in the conjugation to AuNPs. Spectroscopic and microscopic studies confirmed the formation of the MPc-AuNP conjugate which was also shown to exhibit improved photophysicochemical properties compared to the free MPc.
- Full Text:
Investigation of photosensitising behaviour of Ni, Pd and Pt phthalocyanines towards phenolic pollutants
- Authors: Ogunbayo, Taofeek Babatunde
- Date: 2011
- Subjects: Phthalocyanines Pollutants Photochemistry Photosensitizing compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4321 , http://hdl.handle.net/10962/d1004979
- Description: Syntheses of various octasubstituted open-shell (Ni(II), Pd(II) and Pt(II)) metallophthalocyanines and their metal-free analogues have been carried out. Spectroscopic characterizations, photophysical and photochemical studies were carried out to determine the effects of these metals on the molecules using the metal-free phthalocyanine analogues as benchmark. Metal-binding studies of few thio-derivatised phthalocyanines were done to increase the number of palladium metal on the phthalocyanine ligands and determine the effect of increasing number of this metal on phthalocyanine properties. Palladium (PdPc) and platinum phthalocyanines (PtPc) gave good triplet and singlet oxygen quantum yields making them suitable for further investigation in application as photosensitisers. Using 4-nitrophenol as model pollutant, photosensitization reactions were carried out under homogenous and heterogeneous conditions. The reactions were monitored using UV-vis spectroscopy. The MPcs were adsorbed on functionalized single wall carbon nanotube (SWCNT-COOH) to form heterogeneous photosensitizers with PtPc failing to adsorb on the SWCNT-COOH. Under the heterogeneous condition, all the PdPcs photosensitization kinetics was consistent with Langmuir-Hinshelwood reaction model. The best photosenstiser, β-palladium dodecylthio phthalocyanine was also deployed in sensitization of oxidation of 4-chlorophenol and pentachlorophenol under homogenous and heterogeneous conditions to establish the ability of the molecules to sensitize oxidation of wide range of phenolic pollutants. Identifications of the products of the reactions were conducted using gas chromatography and high pressure liquid chromatography (HPLC) hyphenated with mass analyzer (LC-MS). Mechanisms of all the reactions were investigated and all the complexes, in spite of reduced lifetime resulting from open-shell nature of the metals, sensitized the reactions through singlet oxygen mediated pathway. All the heterogeneous sensitisers were recyclable in the 4- nitrophenol oxidation but β-palladium dodecylthio phthalocyanine proved unrecyclable in the oxidation of pentachlorophenol.
- Full Text:
- Authors: Ogunbayo, Taofeek Babatunde
- Date: 2011
- Subjects: Phthalocyanines Pollutants Photochemistry Photosensitizing compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4321 , http://hdl.handle.net/10962/d1004979
- Description: Syntheses of various octasubstituted open-shell (Ni(II), Pd(II) and Pt(II)) metallophthalocyanines and their metal-free analogues have been carried out. Spectroscopic characterizations, photophysical and photochemical studies were carried out to determine the effects of these metals on the molecules using the metal-free phthalocyanine analogues as benchmark. Metal-binding studies of few thio-derivatised phthalocyanines were done to increase the number of palladium metal on the phthalocyanine ligands and determine the effect of increasing number of this metal on phthalocyanine properties. Palladium (PdPc) and platinum phthalocyanines (PtPc) gave good triplet and singlet oxygen quantum yields making them suitable for further investigation in application as photosensitisers. Using 4-nitrophenol as model pollutant, photosensitization reactions were carried out under homogenous and heterogeneous conditions. The reactions were monitored using UV-vis spectroscopy. The MPcs were adsorbed on functionalized single wall carbon nanotube (SWCNT-COOH) to form heterogeneous photosensitizers with PtPc failing to adsorb on the SWCNT-COOH. Under the heterogeneous condition, all the PdPcs photosensitization kinetics was consistent with Langmuir-Hinshelwood reaction model. The best photosenstiser, β-palladium dodecylthio phthalocyanine was also deployed in sensitization of oxidation of 4-chlorophenol and pentachlorophenol under homogenous and heterogeneous conditions to establish the ability of the molecules to sensitize oxidation of wide range of phenolic pollutants. Identifications of the products of the reactions were conducted using gas chromatography and high pressure liquid chromatography (HPLC) hyphenated with mass analyzer (LC-MS). Mechanisms of all the reactions were investigated and all the complexes, in spite of reduced lifetime resulting from open-shell nature of the metals, sensitized the reactions through singlet oxygen mediated pathway. All the heterogeneous sensitisers were recyclable in the 4- nitrophenol oxidation but β-palladium dodecylthio phthalocyanine proved unrecyclable in the oxidation of pentachlorophenol.
- Full Text:
Surface properties and electrocatalytic applications of metallophthalocyanines confined on electrode surfaces
- Authors: Akinbulu, Isaac Adebayo
- Date: 2011
- Subjects: Phthalocyanines Electrochemistry Electrocatalysis Pesticides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4365 , http://hdl.handle.net/10962/d1005030
- Description: New cobalt (13, 16 19 and 22), manganese (14, 17, 20 and 23) and iron (15, 18, 21 and 24)phthalocyanine complexes were synthesized and characterized. The UV-Vis spectral properties of the complexes were typical of the nature of central metal and position of substituent on the Pc ligand. Their electrochemical behaviors were signatures of the central metals, with varying influences of the nature and position of substituents. Nanocomposite of complex 18 and single walled carbon nanotubes (SWCNTs) (SWCNT-18)was fabricated. Formation of this nano-composite was confirmed by infrared (IR)spectroscopy, X-ray diffraction (XRD) spectroscopy and transmission electron microscopy (TEM). Self-assembled monolayers (SAMs) of SWCNT-18, complexes 13-15, and 20 were electropolymerized on glassy carbon electrodes (GCE). Complex 14 was also electrodeposited on GCE. Surface properties of the SAMs were consistent with the molecular feature of the substituent and the nature of central metal in the adsorbed species, while those of the MnPc modified GCEs were dependent on point of substitution and number of substituent. The SAM-modified gold electrodes were used for the electrocatalytic oxidation of the carbamate insecticide, carbofuran. Amplification of the current signal of the insecticide, at more energetically feasible oxidation potentials, on the SAM-modified gold electrodes, relative to bare gold electrode,justified electrocatalysis. There was enhanced sensitivity (attributed to the presence of SWCNT) of the SWCNT-18-SAM-modified gold electrode towards carbofuran, relative to the signals observed on the other SAMs. Current response of the insecticide,bendiocarb, was also intensified, at more favorable oxidation potentials, on the MnPc (14 and 17) modified GCEs, relative to the response on bare GCE, substantiating electrocatalysis. Also, catalysis of the oxidation of the herbicide, bentazon, was observed on polymeric film of complex 20. The current response of the herbicide on this film was better than that observed on bare GCE. Electrocatalysis of the analytes, on the respective modified electrodes, occurred via closely related mechanisms.
- Full Text:
- Authors: Akinbulu, Isaac Adebayo
- Date: 2011
- Subjects: Phthalocyanines Electrochemistry Electrocatalysis Pesticides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4365 , http://hdl.handle.net/10962/d1005030
- Description: New cobalt (13, 16 19 and 22), manganese (14, 17, 20 and 23) and iron (15, 18, 21 and 24)phthalocyanine complexes were synthesized and characterized. The UV-Vis spectral properties of the complexes were typical of the nature of central metal and position of substituent on the Pc ligand. Their electrochemical behaviors were signatures of the central metals, with varying influences of the nature and position of substituents. Nanocomposite of complex 18 and single walled carbon nanotubes (SWCNTs) (SWCNT-18)was fabricated. Formation of this nano-composite was confirmed by infrared (IR)spectroscopy, X-ray diffraction (XRD) spectroscopy and transmission electron microscopy (TEM). Self-assembled monolayers (SAMs) of SWCNT-18, complexes 13-15, and 20 were electropolymerized on glassy carbon electrodes (GCE). Complex 14 was also electrodeposited on GCE. Surface properties of the SAMs were consistent with the molecular feature of the substituent and the nature of central metal in the adsorbed species, while those of the MnPc modified GCEs were dependent on point of substitution and number of substituent. The SAM-modified gold electrodes were used for the electrocatalytic oxidation of the carbamate insecticide, carbofuran. Amplification of the current signal of the insecticide, at more energetically feasible oxidation potentials, on the SAM-modified gold electrodes, relative to bare gold electrode,justified electrocatalysis. There was enhanced sensitivity (attributed to the presence of SWCNT) of the SWCNT-18-SAM-modified gold electrode towards carbofuran, relative to the signals observed on the other SAMs. Current response of the insecticide,bendiocarb, was also intensified, at more favorable oxidation potentials, on the MnPc (14 and 17) modified GCEs, relative to the response on bare GCE, substantiating electrocatalysis. Also, catalysis of the oxidation of the herbicide, bentazon, was observed on polymeric film of complex 20. The current response of the herbicide on this film was better than that observed on bare GCE. Electrocatalysis of the analytes, on the respective modified electrodes, occurred via closely related mechanisms.
- Full Text:
The photophysical properties of low symmetry phthalocyanines in conjunction with quantum dots
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) 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-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (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. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) 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-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (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. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
Photophysical and photoelectrochemical properties of water soluble metallophthalocyanines
- Authors: Masilela, Nkosiphile
- Date: 2010
- Subjects: Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4330 , http://hdl.handle.net/10962/d1004991 , Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Description: This work presents the synthesis, characterization, photophysicochemical and photoelectrochemical properties of anionic octa-caboxylated (MOCPcs), tetra-sulfonated (MTSPcs) and quaternized cationic (Q(T-2-Py)MPcs) water soluble aluminium, gallium, silicon, titanium and zinc phthalocynines. The peripherally tetra-substituted cationic (Q(T-2-Py)MPcs) and anionic (MTSPcs) were found to be aggregated in aqueous media, yet the octa-carboxylated (MOCPcs) counterparts were monomeric in solution. Cremophor EL (CEL) was used as a disaggregating agent, all the aggregated complexes disaggregated partially or completely in the presence of CEL. The photophysicochemical properties of aggregated complexes were investigated both in the presence of CEL and in aqueous media of pH 11 alone. Low triplet, singlet oxygen and fluorescence quantum yield were obtained in aqueous media (especially for the aggregated complexes) but a high improvement was achieved upon addition of CEL. The gallium complexes ((OH)GaOCPc and (OH)GaTSPc) showed good photophysicochemical properties with higher triplet and singlet oxygen quantum yields. For photoelectrochemistry the (MPcs) dyes were adsorbed to nanoporous ZnO, electrodeposited in the presence of eosin Y as structure directing agent (SDA) on FTO substrates by refluxing or soaking the films in a solution containing the dye of interest such that a full surface coverage was achieved. Quaternized cationic (Q(T-2-Py)MPc) and tetrasulfonated (MTSPcs) phthalocyanines formed strong aggregates when deposited on the surface of FTO/ZnO substrate leading. High external (IPCE) and internal (APCE) quantum efficiencies of up to 50.6% and 96.7% were achieved for the OTiOCPc complex. There was a lower overall cell efficiency for quaternized and tetrasulfonated metallophthalocyanines because of the strong aggregates when they were on the surface of the electrodes. Among the studied materials, OTiOCPc gave the highest overall cell efficiency of phthalocyanine electrodeposited on ZnO of so far = 0.48%.
- Full Text:
- Authors: Masilela, Nkosiphile
- Date: 2010
- Subjects: Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4330 , http://hdl.handle.net/10962/d1004991 , Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Description: This work presents the synthesis, characterization, photophysicochemical and photoelectrochemical properties of anionic octa-caboxylated (MOCPcs), tetra-sulfonated (MTSPcs) and quaternized cationic (Q(T-2-Py)MPcs) water soluble aluminium, gallium, silicon, titanium and zinc phthalocynines. The peripherally tetra-substituted cationic (Q(T-2-Py)MPcs) and anionic (MTSPcs) were found to be aggregated in aqueous media, yet the octa-carboxylated (MOCPcs) counterparts were monomeric in solution. Cremophor EL (CEL) was used as a disaggregating agent, all the aggregated complexes disaggregated partially or completely in the presence of CEL. The photophysicochemical properties of aggregated complexes were investigated both in the presence of CEL and in aqueous media of pH 11 alone. Low triplet, singlet oxygen and fluorescence quantum yield were obtained in aqueous media (especially for the aggregated complexes) but a high improvement was achieved upon addition of CEL. The gallium complexes ((OH)GaOCPc and (OH)GaTSPc) showed good photophysicochemical properties with higher triplet and singlet oxygen quantum yields. For photoelectrochemistry the (MPcs) dyes were adsorbed to nanoporous ZnO, electrodeposited in the presence of eosin Y as structure directing agent (SDA) on FTO substrates by refluxing or soaking the films in a solution containing the dye of interest such that a full surface coverage was achieved. Quaternized cationic (Q(T-2-Py)MPc) and tetrasulfonated (MTSPcs) phthalocyanines formed strong aggregates when deposited on the surface of FTO/ZnO substrate leading. High external (IPCE) and internal (APCE) quantum efficiencies of up to 50.6% and 96.7% were achieved for the OTiOCPc complex. There was a lower overall cell efficiency for quaternized and tetrasulfonated metallophthalocyanines because of the strong aggregates when they were on the surface of the electrodes. Among the studied materials, OTiOCPc gave the highest overall cell efficiency of phthalocyanine electrodeposited on ZnO of so far = 0.48%.
- Full Text:
Photophysical studies of zinc and indium tetraaminophthalocyanines in the presence of CdTe quantum dots
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
Photophysiochemical studies of d¹⁰ metallophthalocyanines and their interaction with nanoparticles
- Chidawanyika, Wadzanai Janet Upenyu
- Authors: Chidawanyika, Wadzanai Janet Upenyu
- Date: 2010
- Subjects: Nanoparticles Phthalocyanines Photochemistry Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4335 , http://hdl.handle.net/10962/d1004996
- Description: The syntheses, extensive spectroscopic characterization, photophysical and photochemical studies have been conducted for a variation of d10 metallophthaloycanines (MPcs). Comparisons have been made taking into consideration the nfluence of the central metal ion, solvent properties, substituent type and position. Coordination to heavy central metals i.e. Hg gives enhanced triplet state properties. Low symmetry metallophthalocyanine complexes were similarly haracterized and the influence of nteractions with nanoparticles on their photophysical and photochemical properties determined. The MPcs have been linked and adsorbed or mixed with nanoparticles i.e. hemically functionalized single-walled carbon nanotubes SWCNT) and mercaptocarboxylic acid capped CdTe quantum dots (QDs) and changes in the spectra accounted for with respect to the proposed conjugate structures. Distinct differences ccur for linked and adsorbed or mixed conjugates in the bsorption, infrared (IR) and Raman spectra and for thermal ravimetric decay profiles, suggesting successful formation f covalent bonds (linked) and point to structurally ifferent materials. SWCNT quench MPc fluorescence by a photoinduced electron transfer mediated process to give low fluorescence quantum yields. The QDs were used as energy transfer donors and facilitate energy transfer, through Förster resonance energy transfer (FRET) from the QDs to the MPcs. Improved FRET efficiencies were found for linked MPc-QD conjugates relative to the mixed species. Photophysicochemical properties of MPcs were, in general, improved as a result of interactions with nanoparticles.
- Full Text:
- Authors: Chidawanyika, Wadzanai Janet Upenyu
- Date: 2010
- Subjects: Nanoparticles Phthalocyanines Photochemistry Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4335 , http://hdl.handle.net/10962/d1004996
- Description: The syntheses, extensive spectroscopic characterization, photophysical and photochemical studies have been conducted for a variation of d10 metallophthaloycanines (MPcs). Comparisons have been made taking into consideration the nfluence of the central metal ion, solvent properties, substituent type and position. Coordination to heavy central metals i.e. Hg gives enhanced triplet state properties. Low symmetry metallophthalocyanine complexes were similarly haracterized and the influence of nteractions with nanoparticles on their photophysical and photochemical properties determined. The MPcs have been linked and adsorbed or mixed with nanoparticles i.e. hemically functionalized single-walled carbon nanotubes SWCNT) and mercaptocarboxylic acid capped CdTe quantum dots (QDs) and changes in the spectra accounted for with respect to the proposed conjugate structures. Distinct differences ccur for linked and adsorbed or mixed conjugates in the bsorption, infrared (IR) and Raman spectra and for thermal ravimetric decay profiles, suggesting successful formation f covalent bonds (linked) and point to structurally ifferent materials. SWCNT quench MPc fluorescence by a photoinduced electron transfer mediated process to give low fluorescence quantum yields. The QDs were used as energy transfer donors and facilitate energy transfer, through Förster resonance energy transfer (FRET) from the QDs to the MPcs. Improved FRET efficiencies were found for linked MPc-QD conjugates relative to the mixed species. Photophysicochemical properties of MPcs were, in general, improved as a result of interactions with nanoparticles.
- Full Text: