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:
- Date Issued: 2013
- 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:
- Date Issued: 2013
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:
- Date Issued: 2013
- 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:
- Date Issued: 2013
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:
- Date Issued: 2013
- 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:
- Date Issued: 2013
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:
- Date Issued: 2013
- 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:
- Date Issued: 2013
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:
- Date Issued: 2012
- 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:
- Date Issued: 2012
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:
- Date Issued: 2011
- 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:
- Date Issued: 2011
Synthesis and photophysical properties of antimony and lead phthalocyanines
- Modibane, Kwena Desmond, Guest
- Authors: Modibane, Kwena Desmond , Guest
- Date: 2009 , 2009-02-27
- Subjects: Phthalocyanines , Photochemistry , Antimony compounds , Lead compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4370 , http://hdl.handle.net/10962/d1005035 , Phthalocyanines , Photochemistry , Antimony compounds , Lead compounds
- Description: This work hereby presents the synthesis, spectroscopic and photophysical properties of newly synthesized lead (PbPc) and antimony (SbPc) phthalocyanines. The complexes are either unsubstituted or substituted at the peripheral and non-peripheral positions with phenoxy, 4-t-butylphenoxy and 4-benzyloxyphenoxy groups. The photophysical properties of these complexes were studied in dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform as solvents. The fluorescence spectra for PbPc complexes were different to that of the excitation spectra due to demetallation upon excitation. On the other hand, the excitation spectra of oxidized antimony (Sb(V)Pc) derivatives were found to be similar to absorption spectra. High triplet quantum yields for PbPc and SbPc complexes ranging from 0.70 to 0.86, low triplet lifetimes (20–60 μs in DMSO, while they were <10 μs in the rest of the solvents) and low fluorescence quantum yields were observed and is attributed to the presence of heavy atoms (Pb and Sb ions). The nonlinear optical properties of PbPc complexes were studied in dimethylsulfoxide. The optical limiting threshold intensity (Ilim) for the PbPc derivatives were calculated and ranged from 2.1 to 6.8 W/cm2. The photodegradation studies of the PbPc and SbPc complexes synthesized showed that then are stable.
- Full Text:
- Date Issued: 2009
- Authors: Modibane, Kwena Desmond , Guest
- Date: 2009 , 2009-02-27
- Subjects: Phthalocyanines , Photochemistry , Antimony compounds , Lead compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4370 , http://hdl.handle.net/10962/d1005035 , Phthalocyanines , Photochemistry , Antimony compounds , Lead compounds
- Description: This work hereby presents the synthesis, spectroscopic and photophysical properties of newly synthesized lead (PbPc) and antimony (SbPc) phthalocyanines. The complexes are either unsubstituted or substituted at the peripheral and non-peripheral positions with phenoxy, 4-t-butylphenoxy and 4-benzyloxyphenoxy groups. The photophysical properties of these complexes were studied in dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform as solvents. The fluorescence spectra for PbPc complexes were different to that of the excitation spectra due to demetallation upon excitation. On the other hand, the excitation spectra of oxidized antimony (Sb(V)Pc) derivatives were found to be similar to absorption spectra. High triplet quantum yields for PbPc and SbPc complexes ranging from 0.70 to 0.86, low triplet lifetimes (20–60 μs in DMSO, while they were <10 μs in the rest of the solvents) and low fluorescence quantum yields were observed and is attributed to the presence of heavy atoms (Pb and Sb ions). The nonlinear optical properties of PbPc complexes were studied in dimethylsulfoxide. The optical limiting threshold intensity (Ilim) for the PbPc derivatives were calculated and ranged from 2.1 to 6.8 W/cm2. The photodegradation studies of the PbPc and SbPc complexes synthesized showed that then are stable.
- Full Text:
- Date Issued: 2009
Synthesis, photophysics and electrochemical study of tin macrocycles
- Authors: Khene, Mielie Samson
- Date: 2008
- Subjects: Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4376 , http://hdl.handle.net/10962/d1005041 , Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Description: Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (35a), octahexyltetrabenzo-5,10,15-triazaporphyrinato dichlorotin(IV) (35b) and octadecylphthalocyaninato dichlorotin(IV) (35c) were synthesized and their photophysical and electrochemical behaviour studied. Complex (35b), containing a CH group in place of one of the aza nitrogen atom of the phthalocyanine core, shows a split Q band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (35a and 35c). In contrast, (35b) shows a triplet quantum yield ΦT = 0.78. The triplet state lifetimes were solvent dependent, and were higher in THF than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring based redox processes. This thesis also reports on the microwave syntheses of tetrasulphonated tin phthalocyanine and tetrasulphonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (< 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The SnTSTBC complex has lower triplet life times and yields, while binding constant and quenching (of bovine serum albumin) constant are lower for SnTSTBC, compared to SnTSPc. Finally Non-peripherally (α) tetra- (40) and octa-(38a) substituted dodecyl-mercapto tin(IV) phthalocyanines where synthesized and the electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for (38a) and (40); the former shows two ring oxidations, while the latter shows only one ring based oxidation. The adsorption kinetics of (38a) and (40) on a gold electrode have been investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy ΔG(ads) of the self-assembled monolayer (SAMs) were evaluated based on the Frumkin isotherm. The interaction factor between adsorbate –adsorbate molecules is also discussed.
- Full Text:
- Date Issued: 2008
- Authors: Khene, Mielie Samson
- Date: 2008
- Subjects: Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4376 , http://hdl.handle.net/10962/d1005041 , Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Description: Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (35a), octahexyltetrabenzo-5,10,15-triazaporphyrinato dichlorotin(IV) (35b) and octadecylphthalocyaninato dichlorotin(IV) (35c) were synthesized and their photophysical and electrochemical behaviour studied. Complex (35b), containing a CH group in place of one of the aza nitrogen atom of the phthalocyanine core, shows a split Q band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (35a and 35c). In contrast, (35b) shows a triplet quantum yield ΦT = 0.78. The triplet state lifetimes were solvent dependent, and were higher in THF than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring based redox processes. This thesis also reports on the microwave syntheses of tetrasulphonated tin phthalocyanine and tetrasulphonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (< 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The SnTSTBC complex has lower triplet life times and yields, while binding constant and quenching (of bovine serum albumin) constant are lower for SnTSTBC, compared to SnTSPc. Finally Non-peripherally (α) tetra- (40) and octa-(38a) substituted dodecyl-mercapto tin(IV) phthalocyanines where synthesized and the electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for (38a) and (40); the former shows two ring oxidations, while the latter shows only one ring based oxidation. The adsorption kinetics of (38a) and (40) on a gold electrode have been investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy ΔG(ads) of the self-assembled monolayer (SAMs) were evaluated based on the Frumkin isotherm. The interaction factor between adsorbate –adsorbate molecules is also discussed.
- Full Text:
- Date Issued: 2008
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