Effect of the nature of nanoparticles on the photophysicochemical properties and photodynamic antimicrobial chemotherapy of phthalocyanines
- Authors: Magadla, Aviwe
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/123107 , vital:35406
- Description: In this work, the syntheses and characterisation of Zn monocaffeic acid tri–tert–butyl phthalocyanine (1), Zn monocarboxyphenoxy tri– tert–butylphenoxyl phthalocyanine (2), tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (3) and tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (5) are presented. Complexes 3 and 5 were further quartenised with 1,3- propanesultone to form corresponding complexes (4) and (6), respectively. Complexes 1 and 2 were covalently linked to amino functionalised nanoparticles (NPs). Complexes 3, 4, 5 and 6 where linked to oleic acid/oleylamine capped (OLA/OLM) silver-iron dimers (Ag-Fe3O4 OLA/OLM) and silver-iron core shell (Ag@Fe3O4 OLA/OLM) NPs via interaction between the nanoparticles and the imino group on the phthalocyanines. The phthalocyanine-NP conjugates afforded an increase in triplet quantum yields with a corresponding decrease in fluorescence quantum yield as compared to the phthalocyanine complexes alone. Complexes 3, 4 and their conjugates were then used for photodynamic antimicrobial chemotherapy on E. coli. The zwitterionic photosensitiser 4 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- Full Text:
- Date Issued: 2020
- Authors: Magadla, Aviwe
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/123107 , vital:35406
- Description: In this work, the syntheses and characterisation of Zn monocaffeic acid tri–tert–butyl phthalocyanine (1), Zn monocarboxyphenoxy tri– tert–butylphenoxyl phthalocyanine (2), tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (3) and tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (5) are presented. Complexes 3 and 5 were further quartenised with 1,3- propanesultone to form corresponding complexes (4) and (6), respectively. Complexes 1 and 2 were covalently linked to amino functionalised nanoparticles (NPs). Complexes 3, 4, 5 and 6 where linked to oleic acid/oleylamine capped (OLA/OLM) silver-iron dimers (Ag-Fe3O4 OLA/OLM) and silver-iron core shell (Ag@Fe3O4 OLA/OLM) NPs via interaction between the nanoparticles and the imino group on the phthalocyanines. The phthalocyanine-NP conjugates afforded an increase in triplet quantum yields with a corresponding decrease in fluorescence quantum yield as compared to the phthalocyanine complexes alone. Complexes 3, 4 and their conjugates were then used for photodynamic antimicrobial chemotherapy on E. coli. The zwitterionic photosensitiser 4 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- Full Text:
- Date Issued: 2020
Metallophthalocyanines linked to metal nanoparticles and folic acid for use in photodynamic therapy of cancer and photoinactivation of bacterial microorganisms.
- Authors: Matlou, Gauta Gold
- Date: 2020
- Subjects: Cancer -- Photochemotherapy , Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166540 , vital:41377
- Description: This thesis presents on the synthesis and characterization of novel asymmetric and symmetrical metallophthalocyanines (MPcs) substituted with carboxylic acid functional groups and centrally metallated with zinc and indium. The MPcs are further covalently linked to cysteine capped silver nanoparticles (cys-AgNPs), amino functionalized magnetic nanoparticles (AMNPs) and folic acid (FA) through an amide bond between the carboxylic group of MPcs and the amino group of FA, cys-AgNPs or AMNPs. The covalent linkage of MPcs to FA improved the water solubility of MPcs and allowed for singlet oxygen quantum yield determination in water. Asymmetric MPcs and their conjugates were found to have improved photochemical and photophysical properties compared to symmetrical MPcs and their conjugates. The heavy atom effect of AMNPs and AgNPs improved the triplet and singlet oxygen quantum yields of MPcs. MPcs and their conjugates (MPc-FA, MPc-AMNPs, MPc-AgNPs) were found to have lower in vitro dark cytotoxicity and higher photodynamic therapy (PDT) activity on MCF-7 breast cancer cells. The water soluble MPc-FA had better PDT activity when compared to MPc-AMNPs due to the active targeting of folic acid-folate binding on cancer cell surface. MPcs and MPc-AgNPs conjugates also showed excellent in vitro cytotoxicity on S. aureus under light irradiation compared to dark cytotoxicity. The photosensitizing properties of MPcs and their conjugates are demonstrated for the first time in this thesis, both on breast cancer cells (MCF-7) through photodynamic therapy and on microorganisms (S. aureus) through photodynamic antimicrobial chemotherapy.
- Full Text:
- Date Issued: 2020
- Authors: Matlou, Gauta Gold
- Date: 2020
- Subjects: Cancer -- Photochemotherapy , Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166540 , vital:41377
- Description: This thesis presents on the synthesis and characterization of novel asymmetric and symmetrical metallophthalocyanines (MPcs) substituted with carboxylic acid functional groups and centrally metallated with zinc and indium. The MPcs are further covalently linked to cysteine capped silver nanoparticles (cys-AgNPs), amino functionalized magnetic nanoparticles (AMNPs) and folic acid (FA) through an amide bond between the carboxylic group of MPcs and the amino group of FA, cys-AgNPs or AMNPs. The covalent linkage of MPcs to FA improved the water solubility of MPcs and allowed for singlet oxygen quantum yield determination in water. Asymmetric MPcs and their conjugates were found to have improved photochemical and photophysical properties compared to symmetrical MPcs and their conjugates. The heavy atom effect of AMNPs and AgNPs improved the triplet and singlet oxygen quantum yields of MPcs. MPcs and their conjugates (MPc-FA, MPc-AMNPs, MPc-AgNPs) were found to have lower in vitro dark cytotoxicity and higher photodynamic therapy (PDT) activity on MCF-7 breast cancer cells. The water soluble MPc-FA had better PDT activity when compared to MPc-AMNPs due to the active targeting of folic acid-folate binding on cancer cell surface. MPcs and MPc-AgNPs conjugates also showed excellent in vitro cytotoxicity on S. aureus under light irradiation compared to dark cytotoxicity. The photosensitizing properties of MPcs and their conjugates are demonstrated for the first time in this thesis, both on breast cancer cells (MCF-7) through photodynamic therapy and on microorganisms (S. aureus) through photodynamic antimicrobial chemotherapy.
- Full Text:
- Date Issued: 2020
Photocatalysis of 4-chloro and 4-nonylphenols using novel symmetric phthalocyanines and asymmetric porphyrin supported on polyacrylonitrite nanofibres
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
BODIPY and porphyrin dyes for direct glucose sensing and optical limiting applications
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
Effect of substituents on the photophysical properties and nonlinear optical properties of asymmetrical zinc(II) phthalocyanine when conjugated to semiconductor quantum dots
- Authors: Mgidlana, Sithi
- Date: 2019
- Subjects: Nonlinear optics , Quantum dots , Phthalocyanines , Zinc
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97152 , vital:31404
- Description: Various characterization techniques have been used to characterize the synthesized asymmetrical zinc phthalocyanines (ZnPc) derivatives. Techniques include Ultraviolet-visible (UV-vis) spectrophotometry, matrix assisted laser desorption time of flight mass spectrometry (MALD-TOF MS), proton nuclear magnetic resonance (1H-NMR), elemental analysis and Fourier-transform infra-red spectroscopy (FT-IR). The complexes are covalently linked to core/shell and core/shell/shell semiconductor quantum dots (SQDs) via amide bond formation. Photophysical properties of complexes improved in the presence of semiconductor quantum dots (SQDs). SQDs contain cadmium/telluride (CdTe) as core, coated in the first shell with zinc selenide (ZnSe) or zinc sulfide (ZnS) and with zinc oxide (ZnO) in second shell. The photophysical properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs are investigated in solution. Triplet quantum yields of complexes improved in the presence of semiconductor quantum dots. The optical limiting behaviour of the Pc complexes and conjugates are assessed using the open aperture Z–scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. Pcs complexes showed good nonlinear optical response with higher nonlinear absorption coefficient. The conjugates afforded higher nonlinear absorption coefficient than Pc complexes alone.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi
- Date: 2019
- Subjects: Nonlinear optics , Quantum dots , Phthalocyanines , Zinc
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97152 , vital:31404
- Description: Various characterization techniques have been used to characterize the synthesized asymmetrical zinc phthalocyanines (ZnPc) derivatives. Techniques include Ultraviolet-visible (UV-vis) spectrophotometry, matrix assisted laser desorption time of flight mass spectrometry (MALD-TOF MS), proton nuclear magnetic resonance (1H-NMR), elemental analysis and Fourier-transform infra-red spectroscopy (FT-IR). The complexes are covalently linked to core/shell and core/shell/shell semiconductor quantum dots (SQDs) via amide bond formation. Photophysical properties of complexes improved in the presence of semiconductor quantum dots (SQDs). SQDs contain cadmium/telluride (CdTe) as core, coated in the first shell with zinc selenide (ZnSe) or zinc sulfide (ZnS) and with zinc oxide (ZnO) in second shell. The photophysical properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs are investigated in solution. Triplet quantum yields of complexes improved in the presence of semiconductor quantum dots. The optical limiting behaviour of the Pc complexes and conjugates are assessed using the open aperture Z–scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. Pcs complexes showed good nonlinear optical response with higher nonlinear absorption coefficient. The conjugates afforded higher nonlinear absorption coefficient than Pc complexes alone.
- Full Text:
- Date Issued: 2019
Photocatalytic treatment of organic and inorganic water pollutants using zinc phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
Photophysicochemical properties and surface-enhanced Raman scattering of phthalocyanine-nanoparticle conjugates
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
Substituent effects on the electrocatalytic activity of cobalt phthalocyanine in the presence of graphene quantum dots
- Centane, Sixolile Sibongiseni
- Authors: Centane, Sixolile Sibongiseni
- Date: 2019
- Subjects: Phthalocyanines , Quantum dots , Electrocatalysis , Electrochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67614 , vital:29121
- Description: The electrocatalytic activity of metallophthalocyanines derivatives is explored. Cobalt monocarboxyphenoxy phthalocyanine (1), cobalt tetracarboxyphenoxy phthalocyanine (2), cobalt tetraaminophenoxy phthalocyanine (3) and cobalt tris-(tert-butylphenoxy) monocarboxyphenoxy phthalocyanine (4) are the phthalocyanines employed in this work. The metallophthalocyanines were employed alone as well as in the presence of the carbon based graphene quantum dots. The electrocatalytic behaviour of functionalized GQDs is also explored herein. The catalytic processes studies were conducted on a glassy carbon electrode surface. Modification of the electrode was achieved by the adsorption method. The materials were adsorbed either alone, as premixed/covalently linked GQDs/Pc conjugates or sequentially. Sequentially adsorbed electrodes involved the phthalocyanines on top or beneath GQDs. Sequentially modified electrodes where the phthalocyanine had higher currents and low detection limits than when the phthalocyanine is underneath. Premixed conjugates showed better activity than the covalently formed conjugates. The nanomaterials synthesized and used in this work were characterized using transmission electron microscopy, UV-Vis spectroscopy, dynamic light scattering, Raman spectroscopy, X-ray diffraction, Atomic Force Microscopy and X-ray photoelectron spectroscopy. The modified electrodes were characterized using cyclic voltammetry and scanning electrochemical spectroscopy. The electrocatalytic activity of the modified electrodes towards the oxidation of hydrazine was evaluated using cyclic voltammetry and chronoamperometry. Superior catalytic activity was observed for the conjugates compared to that of the individual conjugates.
- Full Text:
- Date Issued: 2019
- Authors: Centane, Sixolile Sibongiseni
- Date: 2019
- Subjects: Phthalocyanines , Quantum dots , Electrocatalysis , Electrochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67614 , vital:29121
- Description: The electrocatalytic activity of metallophthalocyanines derivatives is explored. Cobalt monocarboxyphenoxy phthalocyanine (1), cobalt tetracarboxyphenoxy phthalocyanine (2), cobalt tetraaminophenoxy phthalocyanine (3) and cobalt tris-(tert-butylphenoxy) monocarboxyphenoxy phthalocyanine (4) are the phthalocyanines employed in this work. The metallophthalocyanines were employed alone as well as in the presence of the carbon based graphene quantum dots. The electrocatalytic behaviour of functionalized GQDs is also explored herein. The catalytic processes studies were conducted on a glassy carbon electrode surface. Modification of the electrode was achieved by the adsorption method. The materials were adsorbed either alone, as premixed/covalently linked GQDs/Pc conjugates or sequentially. Sequentially adsorbed electrodes involved the phthalocyanines on top or beneath GQDs. Sequentially modified electrodes where the phthalocyanine had higher currents and low detection limits than when the phthalocyanine is underneath. Premixed conjugates showed better activity than the covalently formed conjugates. The nanomaterials synthesized and used in this work were characterized using transmission electron microscopy, UV-Vis spectroscopy, dynamic light scattering, Raman spectroscopy, X-ray diffraction, Atomic Force Microscopy and X-ray photoelectron spectroscopy. The modified electrodes were characterized using cyclic voltammetry and scanning electrochemical spectroscopy. The electrocatalytic activity of the modified electrodes towards the oxidation of hydrazine was evaluated using cyclic voltammetry and chronoamperometry. Superior catalytic activity was observed for the conjugates compared to that of the individual conjugates.
- Full Text:
- Date Issued: 2019
Syntheses and photophysico-chemical properties of phthalocyanines in the presence of silica nanoparticles
- Authors: Peteni, Siwaphiwe
- Date: 2019
- Subjects: Phthalocyanines , Silica , Nanoparticles , Bioconjugates
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67592 , vital:29118
- Description: This thesis reports on the syntheses and characterizationof symmetrical (charged and neutral), asymmetrical (neutral) metallophthalocyanines (MPcs) and subphthalocyanines (SubPcs). The charged and neutral Pcs were physically doped onto silica nanoparticles (SiNPs). The asymmetrical MPc was also chemically linked to SiNPs. Spectroscopic and microscopic techniques were used to confirm the formation of SiNPs-MPc conjugates. The photophysics and photochemistry of the MPcs were assessed when alone and in conjugates (with SiNPs). The studies showed no significant changes in fluorescence quantum yields (ϕF) and fluorescence lifetimes (ϕF) of MPcs following doping except for 2-SiNPs (2 = Zn tetraaminophenoxyphthalocyanines) and 6-SiNPs (doped) (6 = Zn tris[(4-(pyridine-4-ylthio)2-thio-4-methylthiazol-5yl) acetic acid phthalocyanine) where there was a decrease in the ϕF value. Also for 1-SiNPs (1 = unsubstituted ZnPc) there was an elongation in τF which could be due to the protection offered by SiNPs. Both charged/neutral MPcs displayed high triplet quantum yields (ϕT) and singlet quantum yields (ϕΔ) following doping except for 2-SiNPs where there was a decrease in the latter. For 1-SiNPs there was an increase in ϕT but a decrease inϕΔ .There wasa decrease in ϕT and an increase in ϕΔfor4-SiNPs (4 = Zn tetrasulfophenoxyphthalocyanine), the decrease in ϕT could be due to the orientation of theMPc in SiNPs. An increase in both ϕT and ϕΔ for 6-SiNPs (linked) compared to 6-SiNPs (doped) was observed. Complex 5 (5 = Zn tetra-kis-(dodecylmercapto) phthalocyanine) showed a low ϕΔ value.
- Full Text:
- Date Issued: 2019
- Authors: Peteni, Siwaphiwe
- Date: 2019
- Subjects: Phthalocyanines , Silica , Nanoparticles , Bioconjugates
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67592 , vital:29118
- Description: This thesis reports on the syntheses and characterizationof symmetrical (charged and neutral), asymmetrical (neutral) metallophthalocyanines (MPcs) and subphthalocyanines (SubPcs). The charged and neutral Pcs were physically doped onto silica nanoparticles (SiNPs). The asymmetrical MPc was also chemically linked to SiNPs. Spectroscopic and microscopic techniques were used to confirm the formation of SiNPs-MPc conjugates. The photophysics and photochemistry of the MPcs were assessed when alone and in conjugates (with SiNPs). The studies showed no significant changes in fluorescence quantum yields (ϕF) and fluorescence lifetimes (ϕF) of MPcs following doping except for 2-SiNPs (2 = Zn tetraaminophenoxyphthalocyanines) and 6-SiNPs (doped) (6 = Zn tris[(4-(pyridine-4-ylthio)2-thio-4-methylthiazol-5yl) acetic acid phthalocyanine) where there was a decrease in the ϕF value. Also for 1-SiNPs (1 = unsubstituted ZnPc) there was an elongation in τF which could be due to the protection offered by SiNPs. Both charged/neutral MPcs displayed high triplet quantum yields (ϕT) and singlet quantum yields (ϕΔ) following doping except for 2-SiNPs where there was a decrease in the latter. For 1-SiNPs there was an increase in ϕT but a decrease inϕΔ .There wasa decrease in ϕT and an increase in ϕΔfor4-SiNPs (4 = Zn tetrasulfophenoxyphthalocyanine), the decrease in ϕT could be due to the orientation of theMPc in SiNPs. An increase in both ϕT and ϕΔ for 6-SiNPs (linked) compared to 6-SiNPs (doped) was observed. Complex 5 (5 = Zn tetra-kis-(dodecylmercapto) phthalocyanine) showed a low ϕΔ value.
- Full Text:
- Date Issued: 2019
Synthesis of indium phthalocyanines for photodynamic antimicrobial chemotherapy and photo-oxidation of pollutants
- Authors: Sindelo, Azole
- Date: 2019
- Subjects: Phthalocyanines , Azo dyes , Indium compounds , Photochemotherapy , Nanoparticles , Photodegradation , Pollutants , Water -- Purification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67581 , vital:29116
- Description: Indium (III) octacarboxyl phthalocyanine (ClInOCPc) alone and when conjugated to magnetic nanoparticles (MNP-ClInOCPc), 2(3),9(10),16(17),23(24)-octapyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOPyPc) and its quaternized derivative 2(3),9(10),16(17),23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOMePyPc) were synthesized. All Pcs were tested for both photodynamic antimicrobial chemotherapy (PACT) of an unknown water sample and photo-degradation of methyl red (MR). The singlet quantum yield (ΦΔ) for the ClInOCPc and MNP-ClInOCPc in PAN polymer fibers were 0.36 and 0.20 respectively using ADMA as a quencher in water. The photo-inactivation of bacteria in a water sample with unknown microbes was tested, with the MNP-ClInOCPc inactivating 90.6 % of the microbes and the ClInOCPc with 84.8 %. When embedded to the polymer, there was 48% bacterial clearance for ClInOCPc and 64% clearance for the MNP-ClInOCPc. The rate of degradation of MR increased with decrease of the MR concentration, with the MNP-ClInOCPc having the fastest rate. For ClInOPyPc and ClInOMePyPc, the singlet quantum yields were 0.46 and 0.33 in dimethylformamide (DMF), respectively. The PACT activity of ClInOMePyPc (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium (III) triiodide (1) (containing 3 positive charges) and 2-[4-(N-methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (2) (containing 4 positive charges). When comparing ClInOMePyPc, 1 and 2, the largest log reduction for E. coli were obtained for complex 2 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2019
- Authors: Sindelo, Azole
- Date: 2019
- Subjects: Phthalocyanines , Azo dyes , Indium compounds , Photochemotherapy , Nanoparticles , Photodegradation , Pollutants , Water -- Purification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67581 , vital:29116
- Description: Indium (III) octacarboxyl phthalocyanine (ClInOCPc) alone and when conjugated to magnetic nanoparticles (MNP-ClInOCPc), 2(3),9(10),16(17),23(24)-octapyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOPyPc) and its quaternized derivative 2(3),9(10),16(17),23(24)-octamethylpyridylsulfanyl phthalocyaninato chloroindium (III) (ClInOMePyPc) were synthesized. All Pcs were tested for both photodynamic antimicrobial chemotherapy (PACT) of an unknown water sample and photo-degradation of methyl red (MR). The singlet quantum yield (ΦΔ) for the ClInOCPc and MNP-ClInOCPc in PAN polymer fibers were 0.36 and 0.20 respectively using ADMA as a quencher in water. The photo-inactivation of bacteria in a water sample with unknown microbes was tested, with the MNP-ClInOCPc inactivating 90.6 % of the microbes and the ClInOCPc with 84.8 %. When embedded to the polymer, there was 48% bacterial clearance for ClInOCPc and 64% clearance for the MNP-ClInOCPc. The rate of degradation of MR increased with decrease of the MR concentration, with the MNP-ClInOCPc having the fastest rate. For ClInOPyPc and ClInOMePyPc, the singlet quantum yields were 0.46 and 0.33 in dimethylformamide (DMF), respectively. The PACT activity of ClInOMePyPc (containing 8 positive charges) was compared to those of 9(10),16(17),23(24)-tri-N-methyl-4-pyridylsulfanyl-2(3)-(4-aminophenoxy) phthalocyaninato chloro indium (III) triiodide (1) (containing 3 positive charges) and 2-[4-(N-methylpyridyloxy) phthalocyaninato] chloroindium (III) iodide (2) (containing 4 positive charges). When comparing ClInOMePyPc, 1 and 2, the largest log reduction for E. coli were obtained for complex 2 containing four positive charges hence showing it is not always the charge that determines the PACT activity, but the bridging atom in the phthalocyanine plays a role.
- Full Text:
- Date Issued: 2019
The preparation of BODIPY and porphyrin dyes and their cyclodextrin inclusion complexes and Pluronic® F-127 encapsulation micelles for use in PDT and PACT
- Authors: Molupe, Nthabeleng
- Date: 2019
- Subjects: Dyes and dyeing -- Chemistry , Drug delivery systems , Fluorescence spectroscopy , Cancer -- Photochemotherapy , Photosensitizing compounds -- Therapeutic use , Cyclodextrins -- Biotechnology , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117574 , vital:34528
- Description: Several novel BODIPY dyes ((4,4′-difluoro-1,7-tetramethyl-3,5-(3-dithiophene)-2,6-diiodo-8-(4-dimethylamino)-4-bora-3a,4a-diaza-s-indacene (1c), 4,4′-difluoro-1,7-tetramethyl-3,5-(3 dithiophene)-2,6-diiodo-8-(4-methylthio)-4-bora-3a,4a-diaza-s-indacene (3c) and 4,4′-difluoro-1,7-tetramethyl-3,5-(4-dibenzyloxybenzene)-2,6-diiodo-8-(4-methylbenzoate)-4 bora-3a,4a-diaza-s-indacene (4c)) and porphyrins (tetraacenaphthylporphyrin (7a) and Sn(IV) tetraacenaphthylporphyrin (7b)) were synthesized and characterized. Previously reported BODIPY dyes (4,4′-difluoro-1,7-tetramethyl-3,5-(2-dihydroxy)-2,6-diiodo-8-(4-bromo)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4′-difluoro-1,7-tetramethyl-3,5-(2-dithiophene)-2,6-diiodo-8-(phenyl)-4-bora-3a,4a-diaza-s-indacene (6)) were also used. Pluronic® F-127 and cyclodextrins were used as solubilizing drug delivery agents for the synthesized BODIPY dyes. The encapsulation of BODIPY dyes with Pluronic® F-127 micelles improved the water solubility of the BODIPY 5. Further modification of Pluronic® F-127 by coating with folate-functionalized chitosan for targeted delivery of BODIPY 1c and 6 was explored. The BODIPY dyes and their encapsulation complexes exhibited significant inhibition of human MCF-7 breast cancer cell growth. When cyclodextrins were used as nanocarriers, the inclusion complexes of BODIPY 4c with mβCD were found to enhance the water-solubility of the dye. Greater photoinactivation of Staphylococcus aureus was observed for the inclusion complexes when compared to the effect of solutions of non-complexed BODIPY 4c. The cyclodextrin inclusion complexes of porphyrin 7b with mβCD were also found to enhance the water-solubility of 7b. When the photodynamic effect was evaluated, solutions of the porphyrin alone and their inclusion complexes were found to have significant photodynamic effects against human MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2019
- Authors: Molupe, Nthabeleng
- Date: 2019
- Subjects: Dyes and dyeing -- Chemistry , Drug delivery systems , Fluorescence spectroscopy , Cancer -- Photochemotherapy , Photosensitizing compounds -- Therapeutic use , Cyclodextrins -- Biotechnology , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117574 , vital:34528
- Description: Several novel BODIPY dyes ((4,4′-difluoro-1,7-tetramethyl-3,5-(3-dithiophene)-2,6-diiodo-8-(4-dimethylamino)-4-bora-3a,4a-diaza-s-indacene (1c), 4,4′-difluoro-1,7-tetramethyl-3,5-(3 dithiophene)-2,6-diiodo-8-(4-methylthio)-4-bora-3a,4a-diaza-s-indacene (3c) and 4,4′-difluoro-1,7-tetramethyl-3,5-(4-dibenzyloxybenzene)-2,6-diiodo-8-(4-methylbenzoate)-4 bora-3a,4a-diaza-s-indacene (4c)) and porphyrins (tetraacenaphthylporphyrin (7a) and Sn(IV) tetraacenaphthylporphyrin (7b)) were synthesized and characterized. Previously reported BODIPY dyes (4,4′-difluoro-1,7-tetramethyl-3,5-(2-dihydroxy)-2,6-diiodo-8-(4-bromo)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4′-difluoro-1,7-tetramethyl-3,5-(2-dithiophene)-2,6-diiodo-8-(phenyl)-4-bora-3a,4a-diaza-s-indacene (6)) were also used. Pluronic® F-127 and cyclodextrins were used as solubilizing drug delivery agents for the synthesized BODIPY dyes. The encapsulation of BODIPY dyes with Pluronic® F-127 micelles improved the water solubility of the BODIPY 5. Further modification of Pluronic® F-127 by coating with folate-functionalized chitosan for targeted delivery of BODIPY 1c and 6 was explored. The BODIPY dyes and their encapsulation complexes exhibited significant inhibition of human MCF-7 breast cancer cell growth. When cyclodextrins were used as nanocarriers, the inclusion complexes of BODIPY 4c with mβCD were found to enhance the water-solubility of the dye. Greater photoinactivation of Staphylococcus aureus was observed for the inclusion complexes when compared to the effect of solutions of non-complexed BODIPY 4c. The cyclodextrin inclusion complexes of porphyrin 7b with mβCD were also found to enhance the water-solubility of 7b. When the photodynamic effect was evaluated, solutions of the porphyrin alone and their inclusion complexes were found to have significant photodynamic effects against human MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2019
BODIPY dyes for singlet oxygen and optical limiting applications
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
Characterisation of surfaces modified with phthalocyanines through click chemistry for applications in electrochemical sensing
- O'Donoghue, Charles St John Nqwabuko
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
- Date Issued: 2018
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
- Date Issued: 2018
Photosensitizer, pH sensing and optical limiting properties of BODIPY dyes
- Authors: May, Aviwe Khanya
- Date: 2018
- Subjects: Dyes and dyeing -- Chemistry , Halogenation , Photochemotherapy , Bromination , Photosensitizing compounds , Nonlinear optics , BODIPY dyes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63964 , vital:28515
- Description: A series of BODIPY dyes have been successfully synthesised and structurally characterised to examine the effect of halogenation at the 2,6-positions and the introduction of styryl and vinylene groups at the 3,5-positions. The photophysical properties were studied, to assess the effect of the enhancement of the rate of intersystem crossing through halogenation on the fluorescence properties and the generation of reactive oxygen species. This is important in the assessment of the suitability of applying these molecules as photosensitizer dyes for photodynamic therapy and photodynamic antimicrobial chemotherapy. Upon bromination, the dyes showed moderately high singlet oxygen quantum yields. The inclusion of BODIPY dyes into cyclodextrins was explored since it makes them water soluble and hence suitable for biomedical applications, but no singlet oxygen was detected in aqueous media for the inclusion complexes. In order to red-shift the main spectral band of the BODIPY dyes into the therapeutic window, styryl groups were introduced at the 3,5-positions via a modified Knoevenagel condensation reaction. Since the main spectral band lies well above 532 nm, the second harmonic of the Nd:YAG laser, there is relatively weak absorbance at this wavelength. The 3,5-distyryl and 3,5-divinylene BODIPY dyes were assessed for their potential utility for application in nonlinear optics (NLO), and they demonstrated typical nonlinear absorption behaviour characterised by reverse saturable absorption (RSA) in z-scan measurements. Furthermore, the dyes possess excellent optical limiting parameters, such as their third-order suspectibility and hyperpolarizability values, in a wide range of solvents. One dye containing dimethylamino moieties on styryl groups attached at the 3,5-positions was assessed for potential application as an on/off fluorescence sensor. The dye proved to be successful, since intramolecular charge transfer in the S1 state was eliminated in the presence of acid and this results in a fluorescence “turn on” effect. This process was found to be reversible with the addition of a base.
- Full Text:
- Date Issued: 2018
- Authors: May, Aviwe Khanya
- Date: 2018
- Subjects: Dyes and dyeing -- Chemistry , Halogenation , Photochemotherapy , Bromination , Photosensitizing compounds , Nonlinear optics , BODIPY dyes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63964 , vital:28515
- Description: A series of BODIPY dyes have been successfully synthesised and structurally characterised to examine the effect of halogenation at the 2,6-positions and the introduction of styryl and vinylene groups at the 3,5-positions. The photophysical properties were studied, to assess the effect of the enhancement of the rate of intersystem crossing through halogenation on the fluorescence properties and the generation of reactive oxygen species. This is important in the assessment of the suitability of applying these molecules as photosensitizer dyes for photodynamic therapy and photodynamic antimicrobial chemotherapy. Upon bromination, the dyes showed moderately high singlet oxygen quantum yields. The inclusion of BODIPY dyes into cyclodextrins was explored since it makes them water soluble and hence suitable for biomedical applications, but no singlet oxygen was detected in aqueous media for the inclusion complexes. In order to red-shift the main spectral band of the BODIPY dyes into the therapeutic window, styryl groups were introduced at the 3,5-positions via a modified Knoevenagel condensation reaction. Since the main spectral band lies well above 532 nm, the second harmonic of the Nd:YAG laser, there is relatively weak absorbance at this wavelength. The 3,5-distyryl and 3,5-divinylene BODIPY dyes were assessed for their potential utility for application in nonlinear optics (NLO), and they demonstrated typical nonlinear absorption behaviour characterised by reverse saturable absorption (RSA) in z-scan measurements. Furthermore, the dyes possess excellent optical limiting parameters, such as their third-order suspectibility and hyperpolarizability values, in a wide range of solvents. One dye containing dimethylamino moieties on styryl groups attached at the 3,5-positions was assessed for potential application as an on/off fluorescence sensor. The dye proved to be successful, since intramolecular charge transfer in the S1 state was eliminated in the presence of acid and this results in a fluorescence “turn on” effect. This process was found to be reversible with the addition of a base.
- Full Text:
- Date Issued: 2018
Characterization and application of phthalocyanine-magnetic nanoparticle conjugates anchored to electrospun polyamide nanofibers
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
Synthesis and characterization of NaYGdF4 upconversion nanoparticles and an investigation of their effects on the spectroscopic properties of two phthalocyanine dyes
- Authors: Taylor, Jessica Mary
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54621 , vital:26594
- Description: Sphere and star shaped NaYGdF4:Yb/Er(Tm) upconversion nanoparticles were successfully synthesized utilizing a methanol assisted thermal decomposition approach and their chemical, spectroscopic and fluorescence properties were fully characterized. In addition, their influence on the spectroscopic and fluorescence properties of two phthalocyanines (Pcs) (unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) and aluminium octacarboxy phthalocyanine (Cl)AlOCPc) was investigated. Upconversion nanoparticles were found to produce characteristic upconversion fluorescence emissions in the blue, green, red and NIR regions and were also shown to possess paramagnetic properties. Simple mixing with an H2Pc in toluene was found to exert no change on the spectroscopic or fluorescence properties of the Pc while covalent conjugation to a (Cl)AlOCPc resulted in a large Q band blue shift accompanied by a decrease in fluorescence lifetimes in DMSO. The red light excitation mediated singlet oxygen generation of the H2Pc mixed with upconversion nanoparticles was investigated and singlet oxygen fluorescence lifetimes were found to decrease in the presence of the nanoparticles. Upconversion mediated singlet oxygen generation, by way of resonance energy transfer to the Pc, was also attempted using 972 nm excitation; however, no singlet oxygen was detected utilizing singlet oxygen NIR emission detection. Pending further work using alternative singlet oxygen detection methods, this suggests that while upconversion nanoparticles possess excellent fluorescent imaging capabilities, they are relatively inefficient in inducing singlet oxygen production simply when mixed with phthalocyanines. Despite this, by combining phthalocyanines and upconversion nanoparticles, we present a system capable of: multimodal imaging, using both upconversion and phthalocyanines emissions, singlet oxygen generation, via direct excitation of the phthalocyanine with red laser light, and, possibly, magnetic resonance imaging, as a result of doping the upconversion nanoparticles with Gd3+ ions.
- Full Text:
- Date Issued: 2014
- Authors: Taylor, Jessica Mary
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54621 , vital:26594
- Description: Sphere and star shaped NaYGdF4:Yb/Er(Tm) upconversion nanoparticles were successfully synthesized utilizing a methanol assisted thermal decomposition approach and their chemical, spectroscopic and fluorescence properties were fully characterized. In addition, their influence on the spectroscopic and fluorescence properties of two phthalocyanines (Pcs) (unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) and aluminium octacarboxy phthalocyanine (Cl)AlOCPc) was investigated. Upconversion nanoparticles were found to produce characteristic upconversion fluorescence emissions in the blue, green, red and NIR regions and were also shown to possess paramagnetic properties. Simple mixing with an H2Pc in toluene was found to exert no change on the spectroscopic or fluorescence properties of the Pc while covalent conjugation to a (Cl)AlOCPc resulted in a large Q band blue shift accompanied by a decrease in fluorescence lifetimes in DMSO. The red light excitation mediated singlet oxygen generation of the H2Pc mixed with upconversion nanoparticles was investigated and singlet oxygen fluorescence lifetimes were found to decrease in the presence of the nanoparticles. Upconversion mediated singlet oxygen generation, by way of resonance energy transfer to the Pc, was also attempted using 972 nm excitation; however, no singlet oxygen was detected utilizing singlet oxygen NIR emission detection. Pending further work using alternative singlet oxygen detection methods, this suggests that while upconversion nanoparticles possess excellent fluorescent imaging capabilities, they are relatively inefficient in inducing singlet oxygen production simply when mixed with phthalocyanines. Despite this, by combining phthalocyanines and upconversion nanoparticles, we present a system capable of: multimodal imaging, using both upconversion and phthalocyanines emissions, singlet oxygen generation, via direct excitation of the phthalocyanine with red laser light, and, possibly, magnetic resonance imaging, as a result of doping the upconversion nanoparticles with Gd3+ ions.
- Full Text:
- Date Issued: 2014
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