Photodynamic therapy characteristics of phthalocyanines in the presence of boron doped detonation nanodiamonds
- Matshitse, Refilwe, Nwaji, Njemuwa, Managa, Muthimuni, Chen, Zhi-Long, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Managa, Muthimuni , Chen, Zhi-Long , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229921 , vital:49723 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102705"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activities of benzothiazole substituted zinc phthalocyanine (Pc): 1 (asymmetrically substituted and composed of no charges), 2 (asymmetrically substituted and composed of three positive charges), and 3 (symmetrically substituted and composed of four positive charges), are presented. The triplet and singlet oxygen quantum yields were highest for complex 2 showing the importance of asymmetry and charge. The complexes are covalently and non-covalently linked to B doped detonation nanodiamonds (B@DNDs) to yield nanohybrids (B@DNDs-1, B@DNDs-2, B@DNDs-3). The presence of B@DNDs, asymmetry and positive charge resulted in improved PDT with the lowest cell viability being observed for B@DNDs-2 at 5%. The cell viability ranged from 5% to 7% for the nanohybrids compared to 19–26% for Pcs alone.
- Full Text:
- Date Issued: 2022
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Managa, Muthimuni , Chen, Zhi-Long , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229921 , vital:49723 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102705"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activities of benzothiazole substituted zinc phthalocyanine (Pc): 1 (asymmetrically substituted and composed of no charges), 2 (asymmetrically substituted and composed of three positive charges), and 3 (symmetrically substituted and composed of four positive charges), are presented. The triplet and singlet oxygen quantum yields were highest for complex 2 showing the importance of asymmetry and charge. The complexes are covalently and non-covalently linked to B doped detonation nanodiamonds (B@DNDs) to yield nanohybrids (B@DNDs-1, B@DNDs-2, B@DNDs-3). The presence of B@DNDs, asymmetry and positive charge resulted in improved PDT with the lowest cell viability being observed for B@DNDs-2 at 5%. The cell viability ranged from 5% to 7% for the nanohybrids compared to 19–26% for Pcs alone.
- Full Text:
- Date Issued: 2022
Electrodeposited Benzothiazole Phthalocyanines for Corrosion Inhibition of Aluminium in Acidic Medium
- Nnaji, Nnaemeka, Nwaji, Njemuwa, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186112 , vital:44464 , xlink:href="https://doi.org/10.1155/2020/8892559"
- Description: Tetrakis[(benzo[d]thiazol-2-yl-thio) phthalocyaninato] gallium(III)chloride (1) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. The aim of this study was to compare the corrosion resistance of electrodeposited metallated phthalocyanines. Scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy (EIS), and polarization confirmed the aluminium corrosion inhibition potentials of complexes 1 and 2. EIS and polarization techniques showed that complex 2 performed better than complex 1, with values from EIS measurements of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution. The importance of electrodeposition in industries and a dearth of research on the use of electrodeposited metallated phthalocyanines necessitated this study, and results show that coatings formed by electrodeposition of 1 and 2 onto aluminium reduced its susceptibility to corrosion attack.
- Full Text:
- Date Issued: 2020
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186112 , vital:44464 , xlink:href="https://doi.org/10.1155/2020/8892559"
- Description: Tetrakis[(benzo[d]thiazol-2-yl-thio) phthalocyaninato] gallium(III)chloride (1) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. The aim of this study was to compare the corrosion resistance of electrodeposited metallated phthalocyanines. Scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy (EIS), and polarization confirmed the aluminium corrosion inhibition potentials of complexes 1 and 2. EIS and polarization techniques showed that complex 2 performed better than complex 1, with values from EIS measurements of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution. The importance of electrodeposition in industries and a dearth of research on the use of electrodeposited metallated phthalocyanines necessitated this study, and results show that coatings formed by electrodeposition of 1 and 2 onto aluminium reduced its susceptibility to corrosion attack.
- Full Text:
- Date Issued: 2020
Theoretical and photodynamic therapy characteristics of heteroatom doped detonation nanodiamonds linked to asymmetrical phthalocyanine for eradication of breast cancer cells
- Matshitse, Refilwe, Tshiwawa, Tendamudzimu, Managa, Muthumuni, Nwaji, Njemuwa, Lobb, Kevin A, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Tshiwawa, Tendamudzimu , Managa, Muthumuni , Nwaji, Njemuwa , Lobb, Kevin A , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186089 , vital:44462 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117465"
- Description: An amide mono substituted benzothiozole phthalocyanine: zinc(II) 3-(4-((3,17,23-tris(4-(benzo [d]thiazol-2-yl)phenoxy)-9-yl)oxy) phenyl)amide phthalocyanine (NH2BzPc) was covalently linked to undoped and heteroatom doped detonation nanodiamonds (DNDs): B@DNDs, P@DNDs, S@DNDs, N@DNDs, and SandN@DNDs There is a drastic decrease in highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy gaps for nanoconjugates compared to DNDs alone. B@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc, and P@DNDs-NH2BzPc showed superior photodynamic therapy (PDT) effects. DNDs-NH2BzPc also had a small HOMO-LUMO gap, but did not show improved PDT activity compared to the Pc alone, suggesting doping of DNDs is important. This study shows improved PDT effect on Michigan Cancer Foundation-7 breast cancer lines at 7.63%, 7.62% and 6.5% cell viability for P@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc and B@DNDs-NH2BzPc, respectively.
- Full Text:
- Date Issued: 2020
- Authors: Matshitse, Refilwe , Tshiwawa, Tendamudzimu , Managa, Muthumuni , Nwaji, Njemuwa , Lobb, Kevin A , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186089 , vital:44462 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117465"
- Description: An amide mono substituted benzothiozole phthalocyanine: zinc(II) 3-(4-((3,17,23-tris(4-(benzo [d]thiazol-2-yl)phenoxy)-9-yl)oxy) phenyl)amide phthalocyanine (NH2BzPc) was covalently linked to undoped and heteroatom doped detonation nanodiamonds (DNDs): B@DNDs, P@DNDs, S@DNDs, N@DNDs, and SandN@DNDs There is a drastic decrease in highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy gaps for nanoconjugates compared to DNDs alone. B@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc, and P@DNDs-NH2BzPc showed superior photodynamic therapy (PDT) effects. DNDs-NH2BzPc also had a small HOMO-LUMO gap, but did not show improved PDT activity compared to the Pc alone, suggesting doping of DNDs is important. This study shows improved PDT effect on Michigan Cancer Foundation-7 breast cancer lines at 7.63%, 7.62% and 6.5% cell viability for P@DNDs-NH2BzPc, SandN@DNDs-NH2BzPc and B@DNDs-NH2BzPc, respectively.
- Full Text:
- Date Issued: 2020
Inhibition of aluminium corrosion using benzothiazole and its phthalocyanine derivative
- Nnaji, Nnaemeka, Nwaji, Njemuwa, Fomo, Gertrude, Mack, John, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186949 , vital:44550 , xlink:href="https://doi.org/10.1007/s12678-019-00538-1"
- Description: Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range from 28.2 to 76.1% for BT and from 71.5 to 82.7% for ClGaBTPc. The latter was a better inhibitor. Scanning electron microscopy and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results.
- Full Text:
- Date Issued: 2019
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186949 , vital:44550 , xlink:href="https://doi.org/10.1007/s12678-019-00538-1"
- Description: Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range from 28.2 to 76.1% for BT and from 71.5 to 82.7% for ClGaBTPc. The latter was a better inhibitor. Scanning electron microscopy and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results.
- Full Text:
- Date Issued: 2019
Nonlinear optical responses of carbazole-substituted phthalocyanines conjugated to graphene quantum dots and in thin films
- Majeed, Shereen A, Nwaji, Njemuwa, Mack, John, Nyokong, Tebello, Makhseed, Saad
- Authors: Majeed, Shereen A , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello , Makhseed, Saad
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186938 , vital:44549 , xlink:href="https://doi.org/10.1016/j.jlumin.2019.04.034"
- Description: Three different phthalocyanine complexes substituted with carbazoles were conjugated to graphene quantum dots (GQDs) through π–π stacking. The morphologies, sizes, and crystallinities of the nanoconjugates were determined using Raman spectroscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The nonlinear optical (NLO) properties of the metallophthalocyanines alone and when conjugated to the GQD nanomaterial in different solvents, as well as after having been embedded in thin films, were studied. The effects of the different substituents and solvents on the NLO properties of the metallophthalocyanines were evaluated. Enhancements in the photophysical properties of the complexes upon conjugation with the nanomaterial were observed. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields, and triplet lifetimes were measured for the complexes, and for their conjugates in DMSO.
- Full Text:
- Date Issued: 2019
- Authors: Majeed, Shereen A , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello , Makhseed, Saad
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186938 , vital:44549 , xlink:href="https://doi.org/10.1016/j.jlumin.2019.04.034"
- Description: Three different phthalocyanine complexes substituted with carbazoles were conjugated to graphene quantum dots (GQDs) through π–π stacking. The morphologies, sizes, and crystallinities of the nanoconjugates were determined using Raman spectroscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The nonlinear optical (NLO) properties of the metallophthalocyanines alone and when conjugated to the GQD nanomaterial in different solvents, as well as after having been embedded in thin films, were studied. The effects of the different substituents and solvents on the NLO properties of the metallophthalocyanines were evaluated. Enhancements in the photophysical properties of the complexes upon conjugation with the nanomaterial were observed. Fluorescence quantum yields, fluorescence lifetimes, triplet quantum yields, and triplet lifetimes were measured for the complexes, and for their conjugates in DMSO.
- Full Text:
- Date Issued: 2019
Photophysical and enhanced nonlinear optical response in asymmetric benzothiazole substituted phthalocyanine covalently linked to semiconductor quantum dots
- Nwaji, Njemuwa, Dingiswayo, Somila, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Dingiswayo, Somila , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187851 , vital:44703 , xlink:href="https://doi.org/10.1016/j.saa.2018.06.098"
- Description: The synthesis of asymmetric benzothiazole substituted phthalocyanines (complexes 3 to 5) and their covalent attachment to glutathione (GSH) functionalized quantum dots (QDs) are reported in this work. Additionally, their photophysical and nonlinear optical properties were investigated. A decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield was observed when the complexes were covalently linked to glutathione (GSH) functionalized cadmium telluride (CdTe) quantum dots. Reverse saturable absorption was found to be predominantly dominated by excited state absorption. The observed limiting threshold values range from 0.29–0.75 J/cm2.
- Full Text:
- Date Issued: 2019
- Authors: Nwaji, Njemuwa , Dingiswayo, Somila , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187851 , vital:44703 , xlink:href="https://doi.org/10.1016/j.saa.2018.06.098"
- Description: The synthesis of asymmetric benzothiazole substituted phthalocyanines (complexes 3 to 5) and their covalent attachment to glutathione (GSH) functionalized quantum dots (QDs) are reported in this work. Additionally, their photophysical and nonlinear optical properties were investigated. A decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield was observed when the complexes were covalently linked to glutathione (GSH) functionalized cadmium telluride (CdTe) quantum dots. Reverse saturable absorption was found to be predominantly dominated by excited state absorption. The observed limiting threshold values range from 0.29–0.75 J/cm2.
- Full Text:
- Date Issued: 2019
Effect of number of positive charges on the photophysical and photodynamic therapy activities of quarternary benzothiazole substituted zinc phthalocyanine
- Matshitse, Refilwe, Nwaji, Njemuwa, Mananga, Muthumuni, Prinsloo, Earl, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Mananga, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187819 , vital:44700 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.08.033"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activity of quaternary benzothiazole substituted zinc phthalocyanine (2, containing two charges, and 3, containing four charges) are reported in this work. Furthermore, the activity of the synthesized complex was compared to non-quaternary derivative (1). Higher triplet and singlet oxygen quantum yields of 0.92 and 0.85, respectively, for quaternized complexes 2 and 3 compared to complex 1 alone. Complexes 1, 2 and 3 showed relatively no dark toxicity against the epithelial breast cancer cells with cell survival of above 90 ± 3%. The quaternary derivatives (2 and 3) showed superior PDT activity with 30% or less of viable cells at concentration of 50.0 μg/mL in comparison to complex 1 alone which further lay credence to the importance of quaternization in the enhancement of PDT activity.
- Full Text:
- Date Issued: 2018
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Mananga, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187819 , vital:44700 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.08.033"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activity of quaternary benzothiazole substituted zinc phthalocyanine (2, containing two charges, and 3, containing four charges) are reported in this work. Furthermore, the activity of the synthesized complex was compared to non-quaternary derivative (1). Higher triplet and singlet oxygen quantum yields of 0.92 and 0.85, respectively, for quaternized complexes 2 and 3 compared to complex 1 alone. Complexes 1, 2 and 3 showed relatively no dark toxicity against the epithelial breast cancer cells with cell survival of above 90 ± 3%. The quaternary derivatives (2 and 3) showed superior PDT activity with 30% or less of viable cells at concentration of 50.0 μg/mL in comparison to complex 1 alone which further lay credence to the importance of quaternization in the enhancement of PDT activity.
- Full Text:
- Date Issued: 2018
Enhanced nonlinear optical response of benzothiazole substituted ball-type phthalocyanines in the presence of metallic nanoparticles
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188149 , vital:44727 , xlink:href="https://doi.org/10.1016/j.optmat.2018.05.052"
- Description: The synthesis of zinc-zinc, gallium-gallium and indium-indium ball-type phthalocyanines (complexes 4, 5 and 6) and the surface assembly of the complexes onto metallic gold and silver nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical dynamics were investigated. Decreases in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to complexes 4, 5 and 6 alone were observed. The mechanism of strong reverse saturable absorption observed was found to be predominantly dependent on excited state absorption. The optical limiting thresholds range from 0.09 to 0.19 J/cm2. Enhanced triplet parameters and nonlinear optical responses were found when the complexes were conjugated to metallic nanoparticles.
- Full Text:
- Date Issued: 2018
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188149 , vital:44727 , xlink:href="https://doi.org/10.1016/j.optmat.2018.05.052"
- Description: The synthesis of zinc-zinc, gallium-gallium and indium-indium ball-type phthalocyanines (complexes 4, 5 and 6) and the surface assembly of the complexes onto metallic gold and silver nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical dynamics were investigated. Decreases in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to complexes 4, 5 and 6 alone were observed. The mechanism of strong reverse saturable absorption observed was found to be predominantly dependent on excited state absorption. The optical limiting thresholds range from 0.09 to 0.19 J/cm2. Enhanced triplet parameters and nonlinear optical responses were found when the complexes were conjugated to metallic nanoparticles.
- Full Text:
- Date Issued: 2018
Glycosylated zinc phthalocyanine-gold nanoparticle conjugates for photodynamic therapy
- Dube, Edith, Oluwole, David O, Nwaji, Njemuwa, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234524 , vital:50205 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.081"
- Description: In this work, we report on the synthesis of tris-[(2,2,7,7-tetramethyltetrahydro-3aH-bis([1,3]dioxolo)[4,5-b:4′,5′-d]pyran-5-yl)methoxy)-2-(4-benzo[d]thiazol-2-ylphenoxyphthalocyaninato] zinc(II) (complex 3) and its linkage to gold nanoparticles (AuNPs) of different shapes through S-Au/N-Au self-assembly. The conjugates of complex 3 (with both gold nanorods (AuNR) and nanospheres (AuNS)), displayed decreased fluorescence quantum yield with corresponding improved triplet and singlet quantum yields compared to complex 3 alone, however 3-AuNR showed improved properties than 3-AuNS. Complex 3 showed relatively low in vitro dark cytotoxicity against the epithelial breast cancer cells with cell survival ≥ 85% at concentration ≤ 160 μg/mL but afforded reduced photodynamic therapy activity which may be due to aggregation. 3-AuNR afforded superior PDT activity with more than 50% viable cells at concentration ≥ 40 μg/mL in comparison to 3-AuNS with more than 50% viable cells at concentration ≥ 80 μg/mL. The superior activity of 3-AuNR is attributed to the photothermal therapy effect since nanorods absorb more light at 680 nm than nanospheres.
- Full Text:
- Date Issued: 2018
- Authors: Dube, Edith , Oluwole, David O , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234524 , vital:50205 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.081"
- Description: In this work, we report on the synthesis of tris-[(2,2,7,7-tetramethyltetrahydro-3aH-bis([1,3]dioxolo)[4,5-b:4′,5′-d]pyran-5-yl)methoxy)-2-(4-benzo[d]thiazol-2-ylphenoxyphthalocyaninato] zinc(II) (complex 3) and its linkage to gold nanoparticles (AuNPs) of different shapes through S-Au/N-Au self-assembly. The conjugates of complex 3 (with both gold nanorods (AuNR) and nanospheres (AuNS)), displayed decreased fluorescence quantum yield with corresponding improved triplet and singlet quantum yields compared to complex 3 alone, however 3-AuNR showed improved properties than 3-AuNS. Complex 3 showed relatively low in vitro dark cytotoxicity against the epithelial breast cancer cells with cell survival ≥ 85% at concentration ≤ 160 μg/mL but afforded reduced photodynamic therapy activity which may be due to aggregation. 3-AuNR afforded superior PDT activity with more than 50% viable cells at concentration ≥ 40 μg/mL in comparison to 3-AuNS with more than 50% viable cells at concentration ≥ 80 μg/mL. The superior activity of 3-AuNR is attributed to the photothermal therapy effect since nanorods absorb more light at 680 nm than nanospheres.
- Full Text:
- Date Issued: 2018
Low symmetric metallophthalocyanine modified electrode via click chemistry for simultaneous detection of heavy metals
- Fomo, Gertrude, Nwaji, Njemuwa, Nyokong, Tebello
- Authors: Fomo, Gertrude , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187914 , vital:44709 , xlink:href="https://doi.org/10.1016/j.jelechem.2018.02.016"
- Description: Beside different methods and materials used to develop electrochemical sensors, the modification of the electrode using click reaction based on metallophthalocyanine (MPc) compounds are shown to improve the stability and sensitivity of the sensor. This work reported the development of electrochemical sensor for mercury (II), Lead (II), copper (II) and cadmium (II) ions detection based on the synthesized novel low symmetry alkyne terminated cobalt Phthalocyanine (CoPc) derivative. Differential pulse stripping voltammetry (DPSV) technique was employed for the first time in simultaneous determination of trace levels of the above metal ions using modified glassy carbon electrode (GCE) via click chemistry. Under the optimum experimental conditions, the anodic peak current is proportional to the concentrations of metal ions over a wide range of 0 to 0.1 mM with nanolevel detection limit of 81.94, 327.71, 55.87 and 347.06 nM and the sensitivity of 866.23 ± 5.48, 215.82 ± 2.16, 1979.48 ± 11.47 and 204.50 ± 1.10 μA/mM for Hg(II), Cu(II), Pb(II) and Cd(II), respectively. The selectivity of the clicked-CoPc modified GCE toward Hg(II), Cu(II), Pb(II), Cd(II) present no interference from these metals ions. The fabricated electrochemical sensor exhibited very good electrochemical properties such as good reproducibility, stability, reusability and is suitable for the detection of heavy metal ions in tap water in our laboratory.
- Full Text:
- Date Issued: 2018
- Authors: Fomo, Gertrude , Nwaji, Njemuwa , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187914 , vital:44709 , xlink:href="https://doi.org/10.1016/j.jelechem.2018.02.016"
- Description: Beside different methods and materials used to develop electrochemical sensors, the modification of the electrode using click reaction based on metallophthalocyanine (MPc) compounds are shown to improve the stability and sensitivity of the sensor. This work reported the development of electrochemical sensor for mercury (II), Lead (II), copper (II) and cadmium (II) ions detection based on the synthesized novel low symmetry alkyne terminated cobalt Phthalocyanine (CoPc) derivative. Differential pulse stripping voltammetry (DPSV) technique was employed for the first time in simultaneous determination of trace levels of the above metal ions using modified glassy carbon electrode (GCE) via click chemistry. Under the optimum experimental conditions, the anodic peak current is proportional to the concentrations of metal ions over a wide range of 0 to 0.1 mM with nanolevel detection limit of 81.94, 327.71, 55.87 and 347.06 nM and the sensitivity of 866.23 ± 5.48, 215.82 ± 2.16, 1979.48 ± 11.47 and 204.50 ± 1.10 μA/mM for Hg(II), Cu(II), Pb(II) and Cd(II), respectively. The selectivity of the clicked-CoPc modified GCE toward Hg(II), Cu(II), Pb(II), Cd(II) present no interference from these metals ions. The fabricated electrochemical sensor exhibited very good electrochemical properties such as good reproducibility, stability, reusability and is suitable for the detection of heavy metal ions in tap water in our laboratory.
- Full Text:
- Date Issued: 2018
Novel nano-dyad of homoleptic sandwich-type phthalocyanines with nitrogen doped graphene quantum dots for nonlinear optics
- Oluwole, David O, Nwaji, Njemuwa, Nene, Lindokuhle C, Mokone, Lesedi, Dube, Edith, Nyokong, Tebello
- Authors: Oluwole, David O , Nwaji, Njemuwa , Nene, Lindokuhle C , Mokone, Lesedi , Dube, Edith , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233386 , vital:50086 , xlink:href="https://doi.org/10.1039/C8NJ01707G"
- Description: The syntheses of neodymium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (2), bis europium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (3), bis dysprosium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (4) and their conjugated analogues with nitrogen doped quantum dots (NGQDs) are reported herein. The optical nonlinearity of the sandwich-type phthalocyanine complexes and their conjugates with NGQDs were studied in dimethyl sulfoxide using the open aperture Z-scan technique at an excitation wavelength of 532 nm with a 10 ns pulse. The nonlinear absorption coefficient (βeff) value of the samples ranges from 15 cm GW−1 to 89.6 cm GW−1. Complex 4 and its conjugates afforded a strong optical limiting behaviour compared to the other samples. These fabricated complexes and their conjugates with NGQDs could serve as a plausible nonlinear optical (NLO) material due to their fascinating NLO properties.
- Full Text:
- Date Issued: 2018
- Authors: Oluwole, David O , Nwaji, Njemuwa , Nene, Lindokuhle C , Mokone, Lesedi , Dube, Edith , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233386 , vital:50086 , xlink:href="https://doi.org/10.1039/C8NJ01707G"
- Description: The syntheses of neodymium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (2), bis europium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (3), bis dysprosium(III) 2,9,16,23-tetrakis-(2,6-di-tert-butyl-4-methylphenoxy)phthalocyanine (4) and their conjugated analogues with nitrogen doped quantum dots (NGQDs) are reported herein. The optical nonlinearity of the sandwich-type phthalocyanine complexes and their conjugates with NGQDs were studied in dimethyl sulfoxide using the open aperture Z-scan technique at an excitation wavelength of 532 nm with a 10 ns pulse. The nonlinear absorption coefficient (βeff) value of the samples ranges from 15 cm GW−1 to 89.6 cm GW−1. Complex 4 and its conjugates afforded a strong optical limiting behaviour compared to the other samples. These fabricated complexes and their conjugates with NGQDs could serve as a plausible nonlinear optical (NLO) material due to their fascinating NLO properties.
- Full Text:
- Date Issued: 2018
Photo-induced resonance energy transfer and nonlinear optical response in ball-type phthalocyanine conjugated to semiconductor and graphene quantum dots
- Nwaji, Njemuwa, Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187959 , vital:44713 , xlink:href="https://doi.org/10.1039/C7NJ05196D"
- Description: The synthesis of ball-type zinc and gallium phthalocyanines (complexes 2 and 3) and their covalent linkage to glutathione (GSH) and amine functionalized quantum dots QDs) are reported in this work. Furthermore, their photophysical, photo-induced resonance energy transfer and optical limiting responses were investigated. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to the phthalocyanine complexes alone. The reverse saturable absorption was found to be dependent on the excited state absorption, and the observed limiting threshold ranged from 0.32 to 1.43 J cm−2. Enhanced triplet parameters and nonlinear optical performance were found when the complexes were covalently linked to semiconductor quantum dots compared to carbon based graphene quantum dots.
- Full Text:
- Date Issued: 2018
- Authors: Nwaji, Njemuwa , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187959 , vital:44713 , xlink:href="https://doi.org/10.1039/C7NJ05196D"
- Description: The synthesis of ball-type zinc and gallium phthalocyanines (complexes 2 and 3) and their covalent linkage to glutathione (GSH) and amine functionalized quantum dots QDs) are reported in this work. Furthermore, their photophysical, photo-induced resonance energy transfer and optical limiting responses were investigated. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to the phthalocyanine complexes alone. The reverse saturable absorption was found to be dependent on the excited state absorption, and the observed limiting threshold ranged from 0.32 to 1.43 J cm−2. Enhanced triplet parameters and nonlinear optical performance were found when the complexes were covalently linked to semiconductor quantum dots compared to carbon based graphene quantum dots.
- Full Text:
- Date Issued: 2018
Photophysical and strong optical limiting properties of ball-type phthalocyanines dimers and their monomeric analogues
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
- Date Issued: 2018
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
- Date Issued: 2018
The photophysicochemical behavior of symmetric and asymmetric zinc phthalocyanines, surface assembled onto gold nanotriangles
- Dube, Edith, Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Dube, Edith , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233310 , vital:50079 , xlink:href="https://doi.org/10.1039/C8NJ02746C"
- Description: The synthesis of a novel asymmetric phthalocyanine, (4-(4-(benzo[d]thiazol-2-yl)phenoxy)-2,10,17-tris(4-(2-carboxyethyl)phenoxy)phthalocyaninatol)zinc(II), complex 3, is reported. Complex 3 together with the previously reported complexes tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (4) and 3-(4-((3,17,23-tris(4-(benzo[d]thiazol-2-yl)phenoxy)phthalocyaninatol)oxy)phenyl)propanoic acid zinc(II) (5), were linked to gold nanotriangles (AuNTs) through S–Au/Au–N self-assembly to afford the conjugates (3-AuNTs, 4-AuNTs and 5-AuNTs). The photophysicochemical behaviour of the complexes and their conjugates were studied. The asymmetric complexes 3 and 5, displayed improved triplet and singlet oxygen quantum yields compared to the symmetric complex 4, while all conjugates displayed improved triplet and singlet oxygen quantum yields compared to their respective complexes alone. The complexes and their conjugates could serve as good candidates for photodynamic therapy.
- Full Text:
- Date Issued: 2018
- Authors: Dube, Edith , Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233310 , vital:50079 , xlink:href="https://doi.org/10.1039/C8NJ02746C"
- Description: The synthesis of a novel asymmetric phthalocyanine, (4-(4-(benzo[d]thiazol-2-yl)phenoxy)-2,10,17-tris(4-(2-carboxyethyl)phenoxy)phthalocyaninatol)zinc(II), complex 3, is reported. Complex 3 together with the previously reported complexes tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (4) and 3-(4-((3,17,23-tris(4-(benzo[d]thiazol-2-yl)phenoxy)phthalocyaninatol)oxy)phenyl)propanoic acid zinc(II) (5), were linked to gold nanotriangles (AuNTs) through S–Au/Au–N self-assembly to afford the conjugates (3-AuNTs, 4-AuNTs and 5-AuNTs). The photophysicochemical behaviour of the complexes and their conjugates were studied. The asymmetric complexes 3 and 5, displayed improved triplet and singlet oxygen quantum yields compared to the symmetric complex 4, while all conjugates displayed improved triplet and singlet oxygen quantum yields compared to their respective complexes alone. The complexes and their conjugates could serve as good candidates for photodynamic therapy.
- Full Text:
- Date Issued: 2018
4-Bis (4-aminophenoxy) phenoxy derivitized phthalocyanine conjugated to metallic nanoparticles
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188965 , vital:44802 , xlink:href="https://doi.org/10.1039/C7NJ02718D"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of 4-(2,4-bis(4-aminophenoxy)phenoxy) phthalocyinato zinc(II) phthalocyanine (6) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques using 532 nm nanosecond pulses. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibit higher excited state absorption cross-section compared to ground state absorption. Enhanced optical limiting performance was observed when complex 6 was conjugated to nanoparticles with 6CB-AuNPs (CB = covalent bond) showing the highest optical limiting threshold of 0.36 J cm−2.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188965 , vital:44802 , xlink:href="https://doi.org/10.1039/C7NJ02718D"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of 4-(2,4-bis(4-aminophenoxy)phenoxy) phthalocyinato zinc(II) phthalocyanine (6) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques using 532 nm nanosecond pulses. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibit higher excited state absorption cross-section compared to ground state absorption. Enhanced optical limiting performance was observed when complex 6 was conjugated to nanoparticles with 6CB-AuNPs (CB = covalent bond) showing the highest optical limiting threshold of 0.36 J cm−2.
- Full Text:
- Date Issued: 2017
Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles
- Nwaji, Njemuwa, Oluwole, David O, Mack, John, Louzada, Marcel, Khene, Samson M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
Investigation of photophysicochemical properties of zinc phthalocyanines conjugated to metallic nanoparticles
- Dube, Edith, Nwaji, Njemuwa, Oluwole, David O, Mack, John, Nyokong, Tebello
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Nwaji, Njemuwa , Oluwole, David O , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233425 , vital:50089 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.09.020"
- Description: The syntheses of zinc(II) tetra–[3–(4–phenoxy) (propanoic acid) phthalocyanine] (2) and zinc(II) mono–[3–(4–phenoxy) (propanoic acid) phthalocyanine (3) are reported in this work. Compounds 2 and 3 were covalently linked to glutathione capped silver (AgNPs–GSH), gold (AuNPs–GSH) and silver-gold alloy (Ag3Au1NPs–GSH) nanoparticles (NPs) via an amide bond formation to afford the conjugates: 2–AgNPs–GSH, 3–AgNPs–GSH, 2–AuNPs–GSH, 3–AuNPs–GSH, 2-Ag3Au1NPs–GSH and 3-Ag3Au1NPs–GSH. The photophysicochemical behaviours of the compounds and their conjugates with NPs were assessed in solution. The conjugates afforded a decrease in fluorescence quantum yields and lifetimes with improved triplet quantum yields in comparison to the compounds. Accordingly, the AgNPs and AuNPs conjugates with the compounds afforded high singlet quantum yields. On the contrary, the conjugates of the alloy afforded decreased singlet quantum yields probably due to the screening effect. The compounds and their conjugates with NPs could serve as a viable and efficacious photosensitizer for photodynamic therapy.
- Full Text:
- Date Issued: 2017
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 M, Mack, John, Oluwole, David O, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Jones, Benjamin M , 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 M , 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 and nonlinear optical study of benzothiazole substituted phthalocyanines in solution and thin films
- Nwaji, Njemuwa, Bankole, Owolabi M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233088 , vital:50055 , xlink:href="https://doi.org/10.1142/S1088424617500079"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (Imm[X(3)(3)]) and hyperpolarizability (γ)γ) at 4.61 × 10-7-7 esu and 3.44 × 10-26-26 esu, respectively, with a low Ilimlim value of 0.06 J.cm-2.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233088 , vital:50055 , xlink:href="https://doi.org/10.1142/S1088424617500079"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (Imm[X(3)(3)]) and hyperpolarizability (γ)γ) at 4.61 × 10-7-7 esu and 3.44 × 10-26-26 esu, respectively, with a low Ilimlim value of 0.06 J.cm-2.
- Full Text:
- Date Issued: 2017