Photodynamic antimicrobial chemotherapy activities of porphyrin- and phthalocyanine-platinum nanoparticle conjugates
- Authors: Managa, Muthumuni Elizabeth
- Date: 2015
- Subjects: Photochemotherapy , Anti-infective agents , Porphyrins , Phthalocyanines , Platinum , Nanoparticles , Bioconjugates , Electrospinning
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4539 , http://hdl.handle.net/10962/d1017919
- Description: This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (1) as well as chloro - (5,10,15,20-tetrakis (4- (4- carboxy phenycarbonoimidoyl) phenyl) porphyrinato) gallium(III) (2) The work also reports on platination of dihydroxosilicon octacarboxyphthalocyanine (OH)₂SiOCPc (3) to give dihydroxosilicontris(diaquaplatinum)octacarboxyphthalocyanine (OH)₂SiOCPc(Pt)₃ (4). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against S. aureus, E. coli and C. albicans. The degree of photo-inactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for 1 when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99 percent of the bacteria have been killed), which is much higher than 3.94 log unit for 1-hexagonal PtNPs and 3.31 log units for 1-unshaped PtNPs. Complex 2 conjugated to hexagonal PtNPs showed 18 nm red shift in the Soret band when compared to 2 alone. Complex 2 and 2-hexagonal PtNPs as well showed promising photodynamic antimicrobial chemotherapy (PACT) activity against S. aureus, E. coli and C. albicans in solution where the log reduction obtained was 4.92, 3.76, and 3.95 respectively for 2-hexagonal PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 2-hexagonl PtNPs in DMF while that of 2 was 0.52 in the same solvent. This resulted in improved PACT activity for 2-hexagonal PtNPs compared to 2. Complex 4 showed slight blue shifting of the absorption spectrum when compared to complex 3 The antimicrobial activity of 4 were promising as the highest log reduction value was observed when compared to the porphyrin conjugates.
- Full Text:
- Date Issued: 2015
- Authors: Managa, Muthumuni Elizabeth
- Date: 2015
- Subjects: Photochemotherapy , Anti-infective agents , Porphyrins , Phthalocyanines , Platinum , Nanoparticles , Bioconjugates , Electrospinning
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4539 , http://hdl.handle.net/10962/d1017919
- Description: This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (1) as well as chloro - (5,10,15,20-tetrakis (4- (4- carboxy phenycarbonoimidoyl) phenyl) porphyrinato) gallium(III) (2) The work also reports on platination of dihydroxosilicon octacarboxyphthalocyanine (OH)₂SiOCPc (3) to give dihydroxosilicontris(diaquaplatinum)octacarboxyphthalocyanine (OH)₂SiOCPc(Pt)₃ (4). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against S. aureus, E. coli and C. albicans. The degree of photo-inactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for 1 when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99 percent of the bacteria have been killed), which is much higher than 3.94 log unit for 1-hexagonal PtNPs and 3.31 log units for 1-unshaped PtNPs. Complex 2 conjugated to hexagonal PtNPs showed 18 nm red shift in the Soret band when compared to 2 alone. Complex 2 and 2-hexagonal PtNPs as well showed promising photodynamic antimicrobial chemotherapy (PACT) activity against S. aureus, E. coli and C. albicans in solution where the log reduction obtained was 4.92, 3.76, and 3.95 respectively for 2-hexagonal PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 2-hexagonl PtNPs in DMF while that of 2 was 0.52 in the same solvent. This resulted in improved PACT activity for 2-hexagonal PtNPs compared to 2. Complex 4 showed slight blue shifting of the absorption spectrum when compared to complex 3 The antimicrobial activity of 4 were promising as the highest log reduction value was observed when compared to the porphyrin conjugates.
- Full Text:
- Date Issued: 2015
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
Synthesis of zinc phthalocyanine derivatives for possible use in photodynamic therapy
- Authors: Matlaba, Pulane Maseleka
- Date: 2003
- Subjects: Photochemotherapy , Electrochemistry , Phthalocyanines , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4374 , http://hdl.handle.net/10962/d1005039 , Photochemotherapy , Electrochemistry , Phthalocyanines , Zinc
- Description: The synthesis of symmetrically and unsymmetrically substituted zinc phthalocyanines (ZnPc) derivatives is done according to reported procedures. The unsymmetrical ZnPc derivatives are synthesized by ring expansion of sub-phthalocyanine complexes. Ring substitution is effected with tert-butyl phenol, naphthol, and hydroxybenzoic acid. Comparison of the redox potentials for the complexes substituted with varying numbers of tert-butyl phenol: 1, 2, 3, 6 and 8 show that the complex with the highest number of substituents are more difficult to oxidize and easier to reduce. Water soluble sulphonated ZnPc (ZnPcSn) was prepared. The possibility of using axial ligation to increase the solubility and the photochemical activity of sulphotnated ZnPc in aqueous solutions was investigated. Pyridine, aminopyridyl and bipyridyl were used as axial ligands. When bipyridyl was used as the axial ligand, solubility of the ZnPcSn increased, shown by the increase in the Q-band of the monomer species in solution and the singlet oxygen quantum yields was relatively higher than that of the unligated ZnPcSn. The singlet oxygen quantum yields by the various complexes in DMF using diphenylisobenzofuran as a chemical quencher for organic solvent were determined. Singlet oxygen quantum yields for the unsymmetrically ring substituted complexes range from 0.22 to 0.68. Photobleaching quantum yields are in the order of 10-5, which means that the complexes are relatively photostable.
- Full Text:
- Date Issued: 2003
- Authors: Matlaba, Pulane Maseleka
- Date: 2003
- Subjects: Photochemotherapy , Electrochemistry , Phthalocyanines , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4374 , http://hdl.handle.net/10962/d1005039 , Photochemotherapy , Electrochemistry , Phthalocyanines , Zinc
- Description: The synthesis of symmetrically and unsymmetrically substituted zinc phthalocyanines (ZnPc) derivatives is done according to reported procedures. The unsymmetrical ZnPc derivatives are synthesized by ring expansion of sub-phthalocyanine complexes. Ring substitution is effected with tert-butyl phenol, naphthol, and hydroxybenzoic acid. Comparison of the redox potentials for the complexes substituted with varying numbers of tert-butyl phenol: 1, 2, 3, 6 and 8 show that the complex with the highest number of substituents are more difficult to oxidize and easier to reduce. Water soluble sulphonated ZnPc (ZnPcSn) was prepared. The possibility of using axial ligation to increase the solubility and the photochemical activity of sulphotnated ZnPc in aqueous solutions was investigated. Pyridine, aminopyridyl and bipyridyl were used as axial ligands. When bipyridyl was used as the axial ligand, solubility of the ZnPcSn increased, shown by the increase in the Q-band of the monomer species in solution and the singlet oxygen quantum yields was relatively higher than that of the unligated ZnPcSn. The singlet oxygen quantum yields by the various complexes in DMF using diphenylisobenzofuran as a chemical quencher for organic solvent were determined. Singlet oxygen quantum yields for the unsymmetrically ring substituted complexes range from 0.22 to 0.68. Photobleaching quantum yields are in the order of 10-5, which means that the complexes are relatively photostable.
- Full Text:
- Date Issued: 2003
Graphene quantum dots and their metallophthalocyanines nanoconjugates as novel photoluminescent nanosensors
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
- Date Issued: 2018
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
- Date Issued: 2018
Nonlinear optical properties of metal free thio alkyl and tert-butyl phenoxy phthalocyanine
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
Photophysical and photoelectrochemical properties of water soluble metallophthalocyanines
- Authors: Masilela, Nkosiphile
- Date: 2010
- Subjects: Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4330 , http://hdl.handle.net/10962/d1004991 , Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Description: This work presents the synthesis, characterization, photophysicochemical and photoelectrochemical properties of anionic octa-caboxylated (MOCPcs), tetra-sulfonated (MTSPcs) and quaternized cationic (Q(T-2-Py)MPcs) water soluble aluminium, gallium, silicon, titanium and zinc phthalocynines. The peripherally tetra-substituted cationic (Q(T-2-Py)MPcs) and anionic (MTSPcs) were found to be aggregated in aqueous media, yet the octa-carboxylated (MOCPcs) counterparts were monomeric in solution. Cremophor EL (CEL) was used as a disaggregating agent, all the aggregated complexes disaggregated partially or completely in the presence of CEL. The photophysicochemical properties of aggregated complexes were investigated both in the presence of CEL and in aqueous media of pH 11 alone. Low triplet, singlet oxygen and fluorescence quantum yield were obtained in aqueous media (especially for the aggregated complexes) but a high improvement was achieved upon addition of CEL. The gallium complexes ((OH)GaOCPc and (OH)GaTSPc) showed good photophysicochemical properties with higher triplet and singlet oxygen quantum yields. For photoelectrochemistry the (MPcs) dyes were adsorbed to nanoporous ZnO, electrodeposited in the presence of eosin Y as structure directing agent (SDA) on FTO substrates by refluxing or soaking the films in a solution containing the dye of interest such that a full surface coverage was achieved. Quaternized cationic (Q(T-2-Py)MPc) and tetrasulfonated (MTSPcs) phthalocyanines formed strong aggregates when deposited on the surface of FTO/ZnO substrate leading. High external (IPCE) and internal (APCE) quantum efficiencies of up to 50.6% and 96.7% were achieved for the OTiOCPc complex. There was a lower overall cell efficiency for quaternized and tetrasulfonated metallophthalocyanines because of the strong aggregates when they were on the surface of the electrodes. Among the studied materials, OTiOCPc gave the highest overall cell efficiency of phthalocyanine electrodeposited on ZnO of so far = 0.48%.
- Full Text:
- Date Issued: 2010
- Authors: Masilela, Nkosiphile
- Date: 2010
- Subjects: Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4330 , http://hdl.handle.net/10962/d1004991 , Phthalocyanines , Electrochemistry , Photoelectrochemistry
- Description: This work presents the synthesis, characterization, photophysicochemical and photoelectrochemical properties of anionic octa-caboxylated (MOCPcs), tetra-sulfonated (MTSPcs) and quaternized cationic (Q(T-2-Py)MPcs) water soluble aluminium, gallium, silicon, titanium and zinc phthalocynines. The peripherally tetra-substituted cationic (Q(T-2-Py)MPcs) and anionic (MTSPcs) were found to be aggregated in aqueous media, yet the octa-carboxylated (MOCPcs) counterparts were monomeric in solution. Cremophor EL (CEL) was used as a disaggregating agent, all the aggregated complexes disaggregated partially or completely in the presence of CEL. The photophysicochemical properties of aggregated complexes were investigated both in the presence of CEL and in aqueous media of pH 11 alone. Low triplet, singlet oxygen and fluorescence quantum yield were obtained in aqueous media (especially for the aggregated complexes) but a high improvement was achieved upon addition of CEL. The gallium complexes ((OH)GaOCPc and (OH)GaTSPc) showed good photophysicochemical properties with higher triplet and singlet oxygen quantum yields. For photoelectrochemistry the (MPcs) dyes were adsorbed to nanoporous ZnO, electrodeposited in the presence of eosin Y as structure directing agent (SDA) on FTO substrates by refluxing or soaking the films in a solution containing the dye of interest such that a full surface coverage was achieved. Quaternized cationic (Q(T-2-Py)MPc) and tetrasulfonated (MTSPcs) phthalocyanines formed strong aggregates when deposited on the surface of FTO/ZnO substrate leading. High external (IPCE) and internal (APCE) quantum efficiencies of up to 50.6% and 96.7% were achieved for the OTiOCPc complex. There was a lower overall cell efficiency for quaternized and tetrasulfonated metallophthalocyanines because of the strong aggregates when they were on the surface of the electrodes. Among the studied materials, OTiOCPc gave the highest overall cell efficiency of phthalocyanine electrodeposited on ZnO of so far = 0.48%.
- Full Text:
- Date Issued: 2010
Nonlinear optical studies of phthalocyanines and triazatetrabenzcorroles in solution and in thin films
- Authors: Mkhize, Nhlakanipho Colin
- Date: 2015
- Subjects: Phthalocyanines , Thin films , Nonlinear optics , Phosphorus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4542 , http://hdl.handle.net/10962/d1017922
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compared with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting intensity of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behaviour than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution. Novel phosphorus triazatetrabenzcorroles (TBC) tetrasubstituted at the α- and β- and octa substituted at the β- positions of the peripheral fused benzene rings with t-butylphenoxy substituents were prepared and characterized. The effects of the substituents and the missing aza-nitrogen on the electronic structures and optical spectroscopy are investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties were investigated to examine whether the lower symmetry that results from the direct pyrrole-pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. Novel phosphorus phthalocyanines, analogous to the triazatetrabenzcorroles were also investigated. Due to their high photodegradation quantum yield however, only the fluorescence quantum yields and lifetimes were able to be determined.
- Full Text:
- Date Issued: 2015
- Authors: Mkhize, Nhlakanipho Colin
- Date: 2015
- Subjects: Phthalocyanines , Thin films , Nonlinear optics , Phosphorus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4542 , http://hdl.handle.net/10962/d1017922
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compared with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting intensity of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behaviour than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution. Novel phosphorus triazatetrabenzcorroles (TBC) tetrasubstituted at the α- and β- and octa substituted at the β- positions of the peripheral fused benzene rings with t-butylphenoxy substituents were prepared and characterized. The effects of the substituents and the missing aza-nitrogen on the electronic structures and optical spectroscopy are investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties were investigated to examine whether the lower symmetry that results from the direct pyrrole-pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined. Novel phosphorus phthalocyanines, analogous to the triazatetrabenzcorroles were also investigated. Due to their high photodegradation quantum yield however, only the fluorescence quantum yields and lifetimes were able to be determined.
- Full Text:
- Date Issued: 2015
Photosensitizing properties of non-transition metal porphyrazines towards the generation of singlet oxygen
- Seotsanyana-Mokhosi, Itumeleng
- Authors: Seotsanyana-Mokhosi, Itumeleng
- Date: 2001 , 2013-05-02
- Subjects: Phthalocyanines , Photosensitization, Biological , Active oxygen -- Physiological effect , Photosensitizing compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4395 , http://hdl.handle.net/10962/d1006086 , Phthalocyanines , Photosensitization, Biological , Active oxygen -- Physiological effect , Photosensitizing compounds
- Description: Metallophthalocyanine complexes containing non-transition metals are very useful as sensitizers for photodynamic therapy, a cure for cancer that is based on visible light activation of tumour localized photo sensitizers. Excited sensitizers generate singlet oxygen as the main hyperactive species that destroy the tumour. Water soluble sensitizers are sought after for the convenience of delivery into the body. Thus, phthalocyanine (pc), tetrapyridinoporphyrazines (tppa) and tetramethyltetrapyridinoporphyrazines (tmtppa) with non-transition central metal atoms of Ge, Si, Sn and Zn were studied. First was the synthesis of these complexes, followed by their characterisation. The characterisation involved the use of ultraviolet and visible absorption spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, electrochemical properties and elemental analysis. Photochemical properties of the complexes were then investigated. Photolysis of these macrocycles showed two processes; -reduction of the dye and photobleaching, which leads to the disintegration of the conjugated chromophore structure of the dye. Photobleaching is the reductive quenching of the excited state of the sensitizers. The intensity of the quenching decreased progressively from tmtppa, tppa to pc metal complexes with photobleaching quantum yields, 6.6 x 10.5⁻¹, 1.8 x 10.5⁻¹ and 5.4 x 10⁻⁶ for Zntmtppa, Zntppa and Znpc, respectively. Efficiency of singlet oxygen sensitization is solvent dependent with very different values obtained for the same compound in different solvents, for example, 0.25 and 0.38 were observed as singlet oxygen quantum yields for Gepc complex in DMSO and DMF respectively. In DMSO the efficiency of ¹O₂ generation decrease considerably from pc to tppa and finally tmtppa. In water Getmtppa exhibits much higher singlet oxygen quantum yield, hence promising to be effective as a sensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2001
- Authors: Seotsanyana-Mokhosi, Itumeleng
- Date: 2001 , 2013-05-02
- Subjects: Phthalocyanines , Photosensitization, Biological , Active oxygen -- Physiological effect , Photosensitizing compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4395 , http://hdl.handle.net/10962/d1006086 , Phthalocyanines , Photosensitization, Biological , Active oxygen -- Physiological effect , Photosensitizing compounds
- Description: Metallophthalocyanine complexes containing non-transition metals are very useful as sensitizers for photodynamic therapy, a cure for cancer that is based on visible light activation of tumour localized photo sensitizers. Excited sensitizers generate singlet oxygen as the main hyperactive species that destroy the tumour. Water soluble sensitizers are sought after for the convenience of delivery into the body. Thus, phthalocyanine (pc), tetrapyridinoporphyrazines (tppa) and tetramethyltetrapyridinoporphyrazines (tmtppa) with non-transition central metal atoms of Ge, Si, Sn and Zn were studied. First was the synthesis of these complexes, followed by their characterisation. The characterisation involved the use of ultraviolet and visible absorption spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, electrochemical properties and elemental analysis. Photochemical properties of the complexes were then investigated. Photolysis of these macrocycles showed two processes; -reduction of the dye and photobleaching, which leads to the disintegration of the conjugated chromophore structure of the dye. Photobleaching is the reductive quenching of the excited state of the sensitizers. The intensity of the quenching decreased progressively from tmtppa, tppa to pc metal complexes with photobleaching quantum yields, 6.6 x 10.5⁻¹, 1.8 x 10.5⁻¹ and 5.4 x 10⁻⁶ for Zntmtppa, Zntppa and Znpc, respectively. Efficiency of singlet oxygen sensitization is solvent dependent with very different values obtained for the same compound in different solvents, for example, 0.25 and 0.38 were observed as singlet oxygen quantum yields for Gepc complex in DMSO and DMF respectively. In DMSO the efficiency of ¹O₂ generation decrease considerably from pc to tppa and finally tmtppa. In water Getmtppa exhibits much higher singlet oxygen quantum yield, hence promising to be effective as a sensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2001
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
Design of pH Sensitive Electrochemical Sensor for Catecholamine Neurotransmitters Detection and the Screening Off of Ascorbic Acid
- Tshenkeng, Keamogetse Tebogo Charlotte
- Authors: Tshenkeng, Keamogetse Tebogo Charlotte
- Date: 2021-10-29
- Subjects: Catecholamines , Electrochemical sensors , Neurotransmitters , Vitamin C , Cobalt , Phthalocyanines , Cobalt (II) tetra-(3-carboxyphenoxy) phthalocyanine (CoTCPhOPc)
- Language: English
- Type: thesis , text
- Identifier: http://hdl.handle.net/10962/176921 , vital:42772
- Description: This study presents the synthesis of cobalt (II) tetra-(3-carboxyphenoxy) phthalocyanine (CoTCPhOPc) through the cyclotetramerization of 4-(3-carboxyphe-noxy)phthalonitrile and its full characterization using Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, magnetic circular dichroism (MCD) spectroscopy, elemental analysis and mass spectrometry. The CoTCPhOPc was then immobilized onto phenylethylamino (PEA) pre-grafted gold electrode surface, Au-PEA using amide coupling reaction through a reaction with NHS and DCC to obtain Au-PEA-CoTCPhOPc. This yielded pH sensitive thin films due to the terminal carboxylic acid (–COOH) functional groups. Electrochemical and surface characterization was conducted to confirm the modification of the bare Au with PEA thin film (Au-PEA) and amide coupling of CoTCPhOPc (Au-PEA-CoTCPhOPc). The Au-PEA-CoTCPhOPc electrode was shown to possess pH selective properties towards negatively charged [Fe(CN)6]3-/4- and positively charged [Ru(NH3)6]2+/3+ redox probes. Au-PEA-CoTCPhOPc electrode surface enabled the detection of catecholamine neurotransmitters (dopamine, norepinephrine and epinephrine) and the screening off of ascorbic acid by means of pH sensitive functional groups. Bare Au and Au-PEA electrodes exhibited electro-oxidation and electroreduction of catecholamine neuro-transmitters and ascorbic acid at higher potentials compared to Au-PEA-CoTCPhOPc. There was no electro-oxidation or electroreduction of ascorbic acid at Au-PEA-CoTCPhOPc. For Au-PEA-CoTCPhOPc, excellent electrocatalytic oxidation with the limit of detection (LoD) determined using 3σ was found to be 1.32 (0.95), 2.11 (1.78) and 3.08 μM for electro-oxidation and electroreduction (in brackets) of dopamine, norepinephrine and epinephrine respectively. The limit of quantification (LoQ) was determined using 10σ and found to be 4.41 (3.17), 7.02 (5.93) and 10.3 μM electro-oxidation and electroreduction (in brackets) for dopamine, norepinephrine and epinephrine respectively. The Au-PEA-CoTCPhOPc thin film was shown to screen off ascorbic acid as no electrocatalytic oxidation was observed for up to 100.0 μM concentration. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Tshenkeng, Keamogetse Tebogo Charlotte
- Date: 2021-10-29
- Subjects: Catecholamines , Electrochemical sensors , Neurotransmitters , Vitamin C , Cobalt , Phthalocyanines , Cobalt (II) tetra-(3-carboxyphenoxy) phthalocyanine (CoTCPhOPc)
- Language: English
- Type: thesis , text
- Identifier: http://hdl.handle.net/10962/176921 , vital:42772
- Description: This study presents the synthesis of cobalt (II) tetra-(3-carboxyphenoxy) phthalocyanine (CoTCPhOPc) through the cyclotetramerization of 4-(3-carboxyphe-noxy)phthalonitrile and its full characterization using Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, magnetic circular dichroism (MCD) spectroscopy, elemental analysis and mass spectrometry. The CoTCPhOPc was then immobilized onto phenylethylamino (PEA) pre-grafted gold electrode surface, Au-PEA using amide coupling reaction through a reaction with NHS and DCC to obtain Au-PEA-CoTCPhOPc. This yielded pH sensitive thin films due to the terminal carboxylic acid (–COOH) functional groups. Electrochemical and surface characterization was conducted to confirm the modification of the bare Au with PEA thin film (Au-PEA) and amide coupling of CoTCPhOPc (Au-PEA-CoTCPhOPc). The Au-PEA-CoTCPhOPc electrode was shown to possess pH selective properties towards negatively charged [Fe(CN)6]3-/4- and positively charged [Ru(NH3)6]2+/3+ redox probes. Au-PEA-CoTCPhOPc electrode surface enabled the detection of catecholamine neurotransmitters (dopamine, norepinephrine and epinephrine) and the screening off of ascorbic acid by means of pH sensitive functional groups. Bare Au and Au-PEA electrodes exhibited electro-oxidation and electroreduction of catecholamine neuro-transmitters and ascorbic acid at higher potentials compared to Au-PEA-CoTCPhOPc. There was no electro-oxidation or electroreduction of ascorbic acid at Au-PEA-CoTCPhOPc. For Au-PEA-CoTCPhOPc, excellent electrocatalytic oxidation with the limit of detection (LoD) determined using 3σ was found to be 1.32 (0.95), 2.11 (1.78) and 3.08 μM for electro-oxidation and electroreduction (in brackets) of dopamine, norepinephrine and epinephrine respectively. The limit of quantification (LoQ) was determined using 10σ and found to be 4.41 (3.17), 7.02 (5.93) and 10.3 μM electro-oxidation and electroreduction (in brackets) for dopamine, norepinephrine and epinephrine respectively. The Au-PEA-CoTCPhOPc thin film was shown to screen off ascorbic acid as no electrocatalytic oxidation was observed for up to 100.0 μM concentration. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
- Full Text:
- Date Issued: 2019
Physicochemical properties and photodynamic therapy activities of indium and zinc phthalocyanine-nanoparticle conjugates
- Authors: Dube, Edith
- Date: 2019
- Subjects: Indium , Zinc , Phthalocyanines , Breast -- Cancer -- Photochemotherapy , Nanoparticles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76506 , vital:30589
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position are reported. The Pcs contain either zinc or indium as central metals and have carboxyphenoxy, phenoxy propanoic acid, benzothiazole phenoxy, thiophine ethoxy or di-O-isopropylidene-α-D-glucopyranose as ring substituents. The Pcs were linked to NPs via an amide bond or through self-assembly. The photophysics and photochemistry of the Pcs were assessed when alone and with conjugates. All the studied Pcs showed good photophysicochemical behaviour with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yield. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy–atom effect obtained from the former. Asymmetrical Pcs displayed higher triplet and singlet oxygen quantum yields than their symmetrical counterparts. The triplet quantum yield, generally increased on linkage to nanoparticles (NPs) due to the heavy–atom effect of gold and silver in NPs. The conjugates to gold nanospheres yielded higher triplet and singlet quantum yields than their gold nanotriangles counterparts due to the higher loading by the former probably encouraged by their relatively small particle size. The in vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. All complexes displayed poor phototoxicity with >50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.
- Full Text:
- Date Issued: 2019
- Authors: Dube, Edith
- Date: 2019
- Subjects: Indium , Zinc , Phthalocyanines , Breast -- Cancer -- Photochemotherapy , Nanoparticles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76506 , vital:30589
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position are reported. The Pcs contain either zinc or indium as central metals and have carboxyphenoxy, phenoxy propanoic acid, benzothiazole phenoxy, thiophine ethoxy or di-O-isopropylidene-α-D-glucopyranose as ring substituents. The Pcs were linked to NPs via an amide bond or through self-assembly. The photophysics and photochemistry of the Pcs were assessed when alone and with conjugates. All the studied Pcs showed good photophysicochemical behaviour with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yield. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy–atom effect obtained from the former. Asymmetrical Pcs displayed higher triplet and singlet oxygen quantum yields than their symmetrical counterparts. The triplet quantum yield, generally increased on linkage to nanoparticles (NPs) due to the heavy–atom effect of gold and silver in NPs. The conjugates to gold nanospheres yielded higher triplet and singlet quantum yields than their gold nanotriangles counterparts due to the higher loading by the former probably encouraged by their relatively small particle size. The in vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. All complexes displayed poor phototoxicity with >50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.
- Full Text:
- Date Issued: 2019
Metallophthalocyanine-gold nanoparticle conjugates for photodynamic antimicrobial chemotherapy
- Mthethwa, Thandekile Phakamisiwe
- Authors: Mthethwa, Thandekile Phakamisiwe
- Date: 2015
- Subjects: Nanochemistry , Phthalocyanines , Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4543 , http://hdl.handle.net/10962/d1017923
- Description: This thesis presents the synthesis of neutral and cationic metallophthalocyanines and their gold nanoparticles conjugates. The spectroscopic characterization of these compounds is presented herein. The studies presented in this work shows that the conjugation of gold nanoparticles influenced both photophysical and photochemical properties. Gold nanoparticles were found to enhance the singlet oxygen quantum yield while lowering the fluorescence quantum yields. This work also looks at the effect of anisotropic gold nanoparticles such as nanorods and bipyramids on the photophysical behaviour of the metallophthalocyanines. The effect of the size of the gold nanorods was investigated herein. The results show that photophysical and photochemical properties can be influenced by both size and shape of the nanoparticles. Physical characterization about the loading of nanoparticles was also looked into. Parameters such as the surface area, the number of surface atoms, the number of atoms as well as the number of nanoparticles loaded on the surface of the phthalocyanines were studied. The self-assembled monolayers formed by phthalocyanines on gold surfaces were studied using the X-ray photoelectron spectroscopy (XPS). The gold nanoparticles synthesized herein include both organic and water soluble, different capping agents (citrate, tetraammonium bromide (TAOBr) and cetrimethylammonium bromide (CTAB). The concentration of the gold nanoparticles was measured on the inductively coupled plasma (ICP) and their size and shape were obtained from the transmission electron microscopy (TEM) images. A cationic aluminium phthalocyanine and its conjugates were used for photoinactivation of bacteria and fungi. The results show significant reduction and higher activity in the presence of gold nanoparticles, especially nanorods. A small chapter in this work presents an attempted work on the binding of metallothionein protein with protophorphyrin (IX). The pH and concentration dependent binding studies were investigated
- Full Text:
- Date Issued: 2015
- Authors: Mthethwa, Thandekile Phakamisiwe
- Date: 2015
- Subjects: Nanochemistry , Phthalocyanines , Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4543 , http://hdl.handle.net/10962/d1017923
- Description: This thesis presents the synthesis of neutral and cationic metallophthalocyanines and their gold nanoparticles conjugates. The spectroscopic characterization of these compounds is presented herein. The studies presented in this work shows that the conjugation of gold nanoparticles influenced both photophysical and photochemical properties. Gold nanoparticles were found to enhance the singlet oxygen quantum yield while lowering the fluorescence quantum yields. This work also looks at the effect of anisotropic gold nanoparticles such as nanorods and bipyramids on the photophysical behaviour of the metallophthalocyanines. The effect of the size of the gold nanorods was investigated herein. The results show that photophysical and photochemical properties can be influenced by both size and shape of the nanoparticles. Physical characterization about the loading of nanoparticles was also looked into. Parameters such as the surface area, the number of surface atoms, the number of atoms as well as the number of nanoparticles loaded on the surface of the phthalocyanines were studied. The self-assembled monolayers formed by phthalocyanines on gold surfaces were studied using the X-ray photoelectron spectroscopy (XPS). The gold nanoparticles synthesized herein include both organic and water soluble, different capping agents (citrate, tetraammonium bromide (TAOBr) and cetrimethylammonium bromide (CTAB). The concentration of the gold nanoparticles was measured on the inductively coupled plasma (ICP) and their size and shape were obtained from the transmission electron microscopy (TEM) images. A cationic aluminium phthalocyanine and its conjugates were used for photoinactivation of bacteria and fungi. The results show significant reduction and higher activity in the presence of gold nanoparticles, especially nanorods. A small chapter in this work presents an attempted work on the binding of metallothionein protein with protophorphyrin (IX). The pH and concentration dependent binding studies were investigated
- Full Text:
- Date Issued: 2015
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
Synthesis, photochemical and photophysical properties of gallium and indium phthalocyanine derivatives
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
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
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
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
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