Nanosecond optical nonlinearities in low symmetry phthalocyanine nanoconjugates studied using the Z-scan technique
- Nwaji, Njemuwa, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188172 , vital:44729 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.08.053"
- Description: In this study, the photophysical, and nonlinear optical limiting properties of low symmetry tris[(4-benzo[d] thiazol-2-ylphenoxy)-2-phenoxyl acetic acid phthalocyaninato] zinc (II) (3) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques at 532 nm. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibits higher excited state absorption cross-section resulting from S1 and T1 compared to ground state absorption. Enhanced optical limiting performance was observed when the complex was conjugated to nanoparticles with 3SA-AuNPs showing the best optical limiting threshold of 0.39 J/cm2.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188172 , vital:44729 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.08.053"
- Description: In this study, the photophysical, and nonlinear optical limiting properties of low symmetry tris[(4-benzo[d] thiazol-2-ylphenoxy)-2-phenoxyl acetic acid phthalocyaninato] zinc (II) (3) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques at 532 nm. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibits higher excited state absorption cross-section resulting from S1 and T1 compared to ground state absorption. Enhanced optical limiting performance was observed when the complex was conjugated to nanoparticles with 3SA-AuNPs showing the best optical limiting threshold of 0.39 J/cm2.
- Full Text:
- Date Issued: 2017
Nonlinear optical dynamics of benzothiazole derivatized phthalocyanines in solution, thin films and when conjugated to nanoparticles
- Nwaji, Njemuwa, Jones, Benjamin, Mack, John, Oluwole, David O, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Jones, Benjamin , Mack, John , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190426 , vital:44993 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.05.042"
- Description: Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Jones, Benjamin , Mack, John , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190426 , vital:44993 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.05.042"
- Description: Benzothiazole phthalocynines complexes: tetrakis[(benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] indium(III) chloride (1) and tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] indium(III) chloride (2) were synthesisized and their nanosecond nonlinear optical behaviours in solution, solid state and when conjugated to metallic nanoparticles were examined and compared to those of the corresponding ZnPc and GaPc which are designated as: tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] zinc(II) (3), tetrakis[(4-benzo[d]thiazol-2-ylphenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5) and tetrakis[(4-benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6). Trends in the electronic structures were identified through a comparison of the UV–vis absorption and magnetic circular dichroism (MCD) spectroscopy of the complexes and calculated spectra predicted by time dependent density functional theory (TD-DFT). Of all the complexes and nanoconjugates, complex 2 (containing sulphur linkages and In as a central metal) gave the best optical limiting behaviour.
- Full Text:
- Date Issued: 2017
Photophysical behavior and photodynamic therapy activity of conjugates of zinc monocarboxyphenoxy phthalocyanine with human serum albumin and chitosan
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
Photophysical properties of a series of alloyed and non-alloyed water-soluble l-cysteine-capped core quantum dots
- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188486 , vital:44758 , xlink:href="https://doi.org/10.1016/j.jallcom.2016.10.276"
- Description: Photophysical properties of quantum dots (QDs) such as their photoluminescence (PL) quantum yield (QY), exciton lifetime and PL stability are important parameters used to unravel their chemical and physical characteristics. In this work, we have comparatively investigated the photophysical properties of a series of L-cysteine-capped non-alloyed (CdTe and CdSe) and alloyed (CdZnTe, CdSeS, CdSeTe and CdSeTeS) core QDs. Each of the QDs varied in their size and PL emission wavelength. We observe no physical relationship between the PL QY of the QDs and their PL stability. Based on the PL stability assessment, CdTe QDs with a high PL QY value of 88% exhibited poor PL stability while moderate PL stability was observed for CdZnTe (QY = 78%); CdSe (QY = 3%); and CdSeTe QDs (QY = ∼3%). Alloyed CdSeS (QY = ∼69%) and CdSeTeS (QY = 23%) QDs exhibited good PL stability and can serve as potential fluorophores for a wide range of chemical and biological applications. Generally, it is proposed that the structural nature of the QDs played a significant role in their overall photophysical properties. The information provided in this work will assist in the selection of core QDs suitable for different applications.
- Full Text:
- Date Issued: 2017
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188486 , vital:44758 , xlink:href="https://doi.org/10.1016/j.jallcom.2016.10.276"
- Description: Photophysical properties of quantum dots (QDs) such as their photoluminescence (PL) quantum yield (QY), exciton lifetime and PL stability are important parameters used to unravel their chemical and physical characteristics. In this work, we have comparatively investigated the photophysical properties of a series of L-cysteine-capped non-alloyed (CdTe and CdSe) and alloyed (CdZnTe, CdSeS, CdSeTe and CdSeTeS) core QDs. Each of the QDs varied in their size and PL emission wavelength. We observe no physical relationship between the PL QY of the QDs and their PL stability. Based on the PL stability assessment, CdTe QDs with a high PL QY value of 88% exhibited poor PL stability while moderate PL stability was observed for CdZnTe (QY = 78%); CdSe (QY = 3%); and CdSeTe QDs (QY = ∼3%). Alloyed CdSeS (QY = ∼69%) and CdSeTeS (QY = 23%) QDs exhibited good PL stability and can serve as potential fluorophores for a wide range of chemical and biological applications. Generally, it is proposed that the structural nature of the QDs played a significant role in their overall photophysical properties. The information provided in this work will assist in the selection of core QDs suitable for different applications.
- Full Text:
- Date Issued: 2017
Photophysical properties of GaCl 5, 10, 15, 20-tetra (1-pyrenyl) porphyrinato incorporated into Pluronic F127 micelle
- Managa, Muthumuni, Britton, Jonathan, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Managa, Muthumuni , Britton, Jonathan , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233101 , vital:50056 , xlink:href="https://doi.org/10.1016/j.jlumin.2016.12.043"
- Description: GaCl 5,10,15,20-Tetra(1-pyrenyl)porphyrin (GaClTPyP) was successfully synthesised and encapsulated into Pluronic F127. The unmetallated 5,10,15,20-tetra(1-pyrenyl)porphyrin (H2TPyP) precursor was also encapsulated into Pluronic F127. The fluorescence quantum yield for GaClTPyP at 0.045 was lower than that of H2TPyP at 0.13 due to the heavy atom effect of Ga in the former which encourages intersystem crossing to the triplet state, lowering the fluorescence. Fluorescence quantum yield values increased when GaClTPyP or H2TPyP were encapsulated in Pluronic F127. GaClTPyP/Pluronic F127 showed higher values of the binding constant (Kb) as well as Stern-Volmer constant (Ksv) when compared to H2ClTPyP/Pluronic F127. It was determined from fluorescence quenching studies for GaClTPyP was located more in the inner core (hydrophobic) of Pluronic F127 and H2TPyP more on the outer region. Single oxygen quantum yields (Ф△) were determined to be 0.32 and 0.53 for GaClTPyP and GaClTPyP/Pluronic F127 respectively, an increase for the latter compared to the former.
- Full Text:
- Date Issued: 2017
- Authors: Managa, Muthumuni , Britton, Jonathan , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233101 , vital:50056 , xlink:href="https://doi.org/10.1016/j.jlumin.2016.12.043"
- Description: GaCl 5,10,15,20-Tetra(1-pyrenyl)porphyrin (GaClTPyP) was successfully synthesised and encapsulated into Pluronic F127. The unmetallated 5,10,15,20-tetra(1-pyrenyl)porphyrin (H2TPyP) precursor was also encapsulated into Pluronic F127. The fluorescence quantum yield for GaClTPyP at 0.045 was lower than that of H2TPyP at 0.13 due to the heavy atom effect of Ga in the former which encourages intersystem crossing to the triplet state, lowering the fluorescence. Fluorescence quantum yield values increased when GaClTPyP or H2TPyP were encapsulated in Pluronic F127. GaClTPyP/Pluronic F127 showed higher values of the binding constant (Kb) as well as Stern-Volmer constant (Ksv) when compared to H2ClTPyP/Pluronic F127. It was determined from fluorescence quenching studies for GaClTPyP was located more in the inner core (hydrophobic) of Pluronic F127 and H2TPyP more on the outer region. Single oxygen quantum yields (Ф△) were determined to be 0.32 and 0.53 for GaClTPyP and GaClTPyP/Pluronic F127 respectively, an increase for the latter compared to the former.
- Full Text:
- Date Issued: 2017
Photophysical studies of meso-tetrakis (4-nitrophenyl) and meso-tetrakis (4-sulfophenyl) gallium porphyrins loaded into Pluronic F127 polymeric micelles
- Managa, Muthumuni, Ngoy, Bokolombe P, Mafukidze, Donovan M, Britton, Jonathan, Nyokong, Tebello
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Mafukidze, Donovan M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233132 , vital:50060 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.08.033"
- Description: 5,10,15,20-Tetra(4-nitrophenyl) porphyrinato gallium chloride (ClGaTNPP) and 5,10,15,20-tetra(4-sulfophenyl) porphyrinato gallium chloride (ClGaTSPP) and their metal free derivatives were successfully synthesised and were added to Pluronic F127 polymeric micelles to form ClGaTNPP-F127 (or H2TNPP-F127) and ClGaTSPP-F127 (or H2TSPP-F127), respectively. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence lifetimes were short-lived upon incorporation into the polymer, compared to the porphyrin alone; suggesting the quenching of the lifetimes of the porphyrin by the polymers. Singlet oxygen quantum yields were determined to be 0.55 and 0.59 for ClGaTSPP and ClGaTSPP-F127, respectively. Thus there is an increase in singlet oxygen quantum yields in the presence of Pluronic F127 compared to the porphyrin alone. ClGaTSPP-F127 (or H2TSPP-F127) showed higher values of the binding constant (Kb) as well as high values of the Stern-Volmer constant (Ksv) compared to ClGaTNPP-F127 (or H2TNPP-F127).
- Full Text:
- Date Issued: 2017
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Mafukidze, Donovan M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233132 , vital:50060 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.08.033"
- Description: 5,10,15,20-Tetra(4-nitrophenyl) porphyrinato gallium chloride (ClGaTNPP) and 5,10,15,20-tetra(4-sulfophenyl) porphyrinato gallium chloride (ClGaTSPP) and their metal free derivatives were successfully synthesised and were added to Pluronic F127 polymeric micelles to form ClGaTNPP-F127 (or H2TNPP-F127) and ClGaTSPP-F127 (or H2TSPP-F127), respectively. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence lifetimes were short-lived upon incorporation into the polymer, compared to the porphyrin alone; suggesting the quenching of the lifetimes of the porphyrin by the polymers. Singlet oxygen quantum yields were determined to be 0.55 and 0.59 for ClGaTSPP and ClGaTSPP-F127, respectively. Thus there is an increase in singlet oxygen quantum yields in the presence of Pluronic F127 compared to the porphyrin alone. ClGaTSPP-F127 (or H2TSPP-F127) showed higher values of the binding constant (Kb) as well as high values of the Stern-Volmer constant (Ksv) compared to ClGaTNPP-F127 (or H2TNPP-F127).
- Full Text:
- Date Issued: 2017
Photophysicochemical behaviour of anionic indium phthalocyanine when grafted onto AgxAuy and porous silica nanoparticles
- Dube, Edith, Oluwole, David O, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
Photophysicochemical behaviour of metallophthalocyanines when doped onto silica nanoparticles
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Date Issued: 2017
The effect of point of substitution and silver based nanoparticles on the photophysical and optical nonlinearity of indium carboxyphenoxy phthalocyanine
- Oluwole, David O, Ngxeke, Sixolisile M, Britton, Jonathan, Nyokong, Tebello
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Ngxeke, Sixolisile M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188596 , vital:44768 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.07.032"
- Description: Indium(III) chloride 1,8(11),15(18),22(25)-tetra-(3-carboxyphenoxy) phthalocyanine (1) and indium(III) chloride 2,9(10),16(17),23(24)-tetra–(3-carboxyphenoxy) phthalocyanine (2) were covalently linked to glutathione capped silver nanoparticles (AgNPs–GSH) and silver selenide/zinc sulfide (Ag2Se/ZnS–GSH) quantum dots via amide bond formation. The photophysical and nonlinear optical behaviour of the metallophthalocyanines and their conjugates with nanoparticles were investigated using the open aperture Z–scan technique. Complex 2 showed enhanced photophysical properties compared to 1. The conjugates revealed improved triplet state quantum yields (except for 1-AgNPs-GSH which afforded lower triplet state quantum yields in comparison to 1) and nonlinear optical activities in comparison to the Pc complexes. The synthesized complexes, nanoparticles and their conjugates could be potential nonlinear optical materials due to their good nonlinear optical activities.
- Full Text:
- Date Issued: 2017
The photophysical studies of Pluronic F127/P123 micelle mixture system loaded with metal free and Zn 5, 10, 15, 20-tetrakis [4-(benzyloxy) phenyl] porphyrins
- Managa, Muthumuni, Ngoy, Bokolombe P, Nyokong, Tebello
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188932 , vital:44799 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.02.018"
- Description: Binary mixtures of Pluronics are studied as drug nanocarriers in this work. H2 and Zn 5,10,15,20-tetrakis[4-(benzyloxy) phenyl] porphyrin were encapsulated onto binary micelle mixture of Pluronic F127/P123. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence quantum yield for H2TBnOPP (ΦF = 0.034) was higher than that of ZnTBnOPP (ΦF = 0.023) and decreased when ZnTBnOPP or H2TBnOPP when in the presence of Pluronic F127/P123 binary mixtures. The kq values were 2.8 × 108 and 3.7 × 108 M−1 s−1, for H2TBnOPP + Pluronic F127/P123 and ZnTBnOPP + Pluronic F127/P123 in water, respectively. The binding constants (Kb) were 1.58 × 105 M−1 and 1.02 × 105 M−1 for ZnTBnOPP + Pluronic F127/P123 and H2TBnOPP + Pluronic F127/P123, respectively.
- Full Text:
- Date Issued: 2017
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188932 , vital:44799 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.02.018"
- Description: Binary mixtures of Pluronics are studied as drug nanocarriers in this work. H2 and Zn 5,10,15,20-tetrakis[4-(benzyloxy) phenyl] porphyrin were encapsulated onto binary micelle mixture of Pluronic F127/P123. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence quantum yield for H2TBnOPP (ΦF = 0.034) was higher than that of ZnTBnOPP (ΦF = 0.023) and decreased when ZnTBnOPP or H2TBnOPP when in the presence of Pluronic F127/P123 binary mixtures. The kq values were 2.8 × 108 and 3.7 × 108 M−1 s−1, for H2TBnOPP + Pluronic F127/P123 and ZnTBnOPP + Pluronic F127/P123 in water, respectively. The binding constants (Kb) were 1.58 × 105 M−1 and 1.02 × 105 M−1 for ZnTBnOPP + Pluronic F127/P123 and H2TBnOPP + Pluronic F127/P123, respectively.
- Full Text:
- Date Issued: 2017