A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg2+ detection
- Musikavanhu, Brian, Muthusamy, Selvaraj, Zhu, Dongwei, Xue, Zhaoli, Yu, Qian, Chivumba, Choonzo N, Mack, John, Nyokong, Tebello, Wang, Shengjun, Zhao, Long
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
- Full Text:
- Date Issued: 2022
- Authors: Musikavanhu, Brian , Muthusamy, Selvaraj , Zhu, Dongwei , Xue, Zhaoli , Yu, Qian , Chivumba, Choonzo N , Mack, John , Nyokong, Tebello , Wang, Shengjun , Zhao, Long
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230362 , vital:49771 , xlink:href="https://doi.org/10.1016/j.saa.2021.120338"
- Description: A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg2+ due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile “turn-off” sensor. The formation of the chelation complex was confirmed by UV–visible absorption and emission spectral measurements, 1H NMR titration and density functional theory calculations. These studies revealed that the probe exhibits high selectivity and sensitivity towards Hg2+ in the presence of other common metal ions. A low detection limit of 23.4 nM was determined and a Job plot confirmed a 2:1 stoichiometry between QT and Hg2+. The potential utility of QT as a sensor for Hg2+ ions in human HeLa cells was determined by confocal fluorescence microscopy, and its suitability for use in the field with environmental samples was tested with Whatman filter paper strips.
- Full Text:
- Date Issued: 2022
Indium phthalocyanines
- Pinar, Sen, Mack, John, Nyokong, Tebello
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
- Full Text:
- Date Issued: 2022
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
- Full Text:
- Date Issued: 2022
Integrated photocatalyst adsorbents based on porphyrin anchored to activated carbon granules for water treatment
- Oyim, James, Amuhaya, Edith K, Matshitse, Refilwe, Mack, John, Nyokong, Tebello
- Authors: Oyim, James , Amuhaya, Edith K , Matshitse, Refilwe , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300101 , vital:57893 , xlink:href="https://doi.org/10.1016/j.cartre.2022.100191"
- Description: Integration of adsorption and photocatalysis processes can lead to several benefits in water treatment. Integrating well-known adsorbents with photocatalysts ensures that all the interesting components are preserved and helps to overcome the serious downsides of each material and technique when operated independently. In this work, we introduce a new concept of combining both absorption and photodegradation mechanisms using organic photocatalytic adsorbents for water purification. This was achieved by formulating photosensitizing hybrids based on a newly synthesized chloroindium (III) 5,10,15,20-tetrakis(4-acetamidophenyl) porphyrin (InTAAP) compound, anchored on oxygen functionalized coconut shell-based activated carbon granules supports. The fashioned integrated photocatalyst adsorbent hybrid (InTAAP(ACO)) was then studied for their adsorption and photodegradation efficiency using methylene blue dye, where InTAAP(ACO) showed excellent photocatalytic activity compared to ACO and unfunctionalized activated carbon granules (AC), with appreciably high and adsorption properties as AC and ACO.
- Full Text:
- Date Issued: 2022
- Authors: Oyim, James , Amuhaya, Edith K , Matshitse, Refilwe , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300101 , vital:57893 , xlink:href="https://doi.org/10.1016/j.cartre.2022.100191"
- Description: Integration of adsorption and photocatalysis processes can lead to several benefits in water treatment. Integrating well-known adsorbents with photocatalysts ensures that all the interesting components are preserved and helps to overcome the serious downsides of each material and technique when operated independently. In this work, we introduce a new concept of combining both absorption and photodegradation mechanisms using organic photocatalytic adsorbents for water purification. This was achieved by formulating photosensitizing hybrids based on a newly synthesized chloroindium (III) 5,10,15,20-tetrakis(4-acetamidophenyl) porphyrin (InTAAP) compound, anchored on oxygen functionalized coconut shell-based activated carbon granules supports. The fashioned integrated photocatalyst adsorbent hybrid (InTAAP(ACO)) was then studied for their adsorption and photodegradation efficiency using methylene blue dye, where InTAAP(ACO) showed excellent photocatalytic activity compared to ACO and unfunctionalized activated carbon granules (AC), with appreciably high and adsorption properties as AC and ACO.
- Full Text:
- Date Issued: 2022
Light-driven antimicrobial therapy of palladium porphyrins and their chitosan immobilization derivatives and their photophysical-chemical properties
- Sen, Pinar, Soy, Rodah, Mgidlana, Sithi, Mack, John, Nyokong, Tebello
- Authors: Sen, Pinar , Soy, Rodah , Mgidlana, Sithi , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300112 , vital:57894 , xlink:href="https://doi.org/10.1016/j.dyepig.2022.110313"
- Description: The emergence of antimicrobial resistance has made the development of photodynamic therapy (PDT) related applications essential, since microorganisms can not form resistance to this method. Porphyrins are well-known photosensitizers for PDT related applications. Thus, the present study outlines the synthesis, characterization and evaluation of the utility of palladium porphyrins and their chitosan inclusion complexes as photosensitizer dye in photodynamic antimicrobial therapy (PACT). Before in vitro cell studies, the photophysical-chemical studies of all obtained structures were performed in solution. It was observed that the immobilization of the porphyrins into the chitosan influenced the photophysical-chemical and PACT activity properties. The determined fluorescence quantum yield was very low, in the range of 0.007–0.028 for all samples indicating the efficient triplet state population to cause high singlet oxygen quantum yield (ΦΔ). The measured ΦΔ values were in the range of 0.51–0.61 for the porphyrins and 0.53–0.66 for porphyrin chitosan immobilization complexes. Our results demonstrate that the PACT activity of cationic porphyrin (P3) and its chitosan immobilization form (P3-Ct) were more efficient in decreasing the number of viable cells up to 100% in vitro.
- Full Text:
- Date Issued: 2022
- Authors: Sen, Pinar , Soy, Rodah , Mgidlana, Sithi , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300112 , vital:57894 , xlink:href="https://doi.org/10.1016/j.dyepig.2022.110313"
- Description: The emergence of antimicrobial resistance has made the development of photodynamic therapy (PDT) related applications essential, since microorganisms can not form resistance to this method. Porphyrins are well-known photosensitizers for PDT related applications. Thus, the present study outlines the synthesis, characterization and evaluation of the utility of palladium porphyrins and their chitosan inclusion complexes as photosensitizer dye in photodynamic antimicrobial therapy (PACT). Before in vitro cell studies, the photophysical-chemical studies of all obtained structures were performed in solution. It was observed that the immobilization of the porphyrins into the chitosan influenced the photophysical-chemical and PACT activity properties. The determined fluorescence quantum yield was very low, in the range of 0.007–0.028 for all samples indicating the efficient triplet state population to cause high singlet oxygen quantum yield (ΦΔ). The measured ΦΔ values were in the range of 0.51–0.61 for the porphyrins and 0.53–0.66 for porphyrin chitosan immobilization complexes. Our results demonstrate that the PACT activity of cationic porphyrin (P3) and its chitosan immobilization form (P3-Ct) were more efficient in decreasing the number of viable cells up to 100% in vitro.
- Full Text:
- Date Issued: 2022
Structural modification of RhIIItriarylcorroles for enhanced electrocatalyzed hydrogen evolution reactions
- Zhu, Weihua, Li, Lihua, Wang, Yu, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Liang, Xu
- Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
- Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
- Full Text:
- Date Issued: 2022
- Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
- Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
- Full Text:
- Date Issued: 2022
Ball-type phthalocyanines and reduced graphene oxide nanoparticles as separate and combined corrosion inhibitors of aluminium in HCl
- Nnaji, Nnaemeka, Nawji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Nawji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185421 , vital:44385 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130279"
- Description: Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron microscopy revealed effective metal surface protection by the inhibitors by formation of protective films.
- Full Text:
- Date Issued: 2021
- Authors: Nnaji, Nnaemeka , Nawji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185421 , vital:44385 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130279"
- Description: Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron microscopy revealed effective metal surface protection by the inhibitors by formation of protective films.
- Full Text:
- Date Issued: 2021
Borneol-triarylcorrole hybrids with chiral-optical response and anticancer behaviours
- Fu, Bo, Wang, Lin, Yu, Xiaoxiao, Fang, Xianying, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Liang, Xu, Xu, Haijun
- Authors: Fu, Bo , Wang, Lin , Yu, Xiaoxiao , Fang, Xianying , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu , Xu, Haijun
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185294 , vital:44362 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109699"
- Description: A series of four multifunctional A2B type H3corroles with meso-borneol substituents at the B position have been synthesized and characterized. A detailed analysis of the optical properties was carried out, and a comparison was made with theoretical calculations to identify the key trends in the structure-property relationships. The meso-borneol substituent couples with the corrole core leading to clear CD signals in the B band region. Enhanced anti-cancer properties are observed in vitro relative to (−)-borneol with cell inhibition rates of up to 94%.
- Full Text:
- Date Issued: 2021
- Authors: Fu, Bo , Wang, Lin , Yu, Xiaoxiao , Fang, Xianying , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu , Xu, Haijun
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185294 , vital:44362 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109699"
- Description: A series of four multifunctional A2B type H3corroles with meso-borneol substituents at the B position have been synthesized and characterized. A detailed analysis of the optical properties was carried out, and a comparison was made with theoretical calculations to identify the key trends in the structure-property relationships. The meso-borneol substituent couples with the corrole core leading to clear CD signals in the B band region. Enhanced anti-cancer properties are observed in vitro relative to (−)-borneol with cell inhibition rates of up to 94%.
- Full Text:
- Date Issued: 2021
Photocytotoxicity of heavy-atom-free thiobarbituric acid functionalized pyrene derivatives against MCF-7 cancer cells
- Babu, Balaji, Ali, Thaslima A, Ochappan, Thivagar, Mack, John, Nyokong, Tebello, Sethuraman, Mathur G
- Authors: Babu, Balaji , Ali, Thaslima A , Ochappan, Thivagar , Mack, John , Nyokong, Tebello , Sethuraman, Mathur G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190556 , vital:45005 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102102"
- Description: Two thiobarbituric acid-functionalized pyrene derivatives (P1, P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2).
- Full Text:
- Date Issued: 2021
- Authors: Babu, Balaji , Ali, Thaslima A , Ochappan, Thivagar , Mack, John , Nyokong, Tebello , Sethuraman, Mathur G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190556 , vital:45005 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102102"
- Description: Two thiobarbituric acid-functionalized pyrene derivatives (P1, P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2).
- Full Text:
- Date Issued: 2021
The photodynamic activities of the gold nanoparticle conjugates of phosphorus (V) and gallium (III) A3 meso-triarylcorroles
- Soy, Rodah C, Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
Thien-2-yl substituted chlorins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy
- Babu, Balaji, Sindelo, Azole, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
- Date Issued: 2021
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
- Date Issued: 2021
Turn-on detection of cysteine by a donor-acceptor type quinoline fluorophore: Exploring the sensing strategy and performance in bioimaging
- Muthusamy, Selvaraj, Zhao, Long, Rajalakshmi, Kanagaraj, Zhu, Dongwei, Soy, Rodah, Mack, John, Nyokong, Tebello, Wang, Shengjun, Lee, Kang-Bong, Zhu, Weihua
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
New difluoroboron complexes based on N, O-chelated Schiff base ligands: Synthesis, characterization, DFT calculations and photophysical and electrochemical properties
- Sen, Pinar, Mpeta, Lekhetho S, Mack, John, Nyokong, Tebello
- Authors: Sen, Pinar , Mpeta, Lekhetho S , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186207 , vital:44473 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117262"
- Description: The synthesis of new Schiff bases and their dinuclear boron complexes is described, along with their characterization by 1H and 13C NMR, FT-IR, and UV–visible absorption spectroscopy, mass spectrometry, and EDX for elemental analysis. The optical and photophysical properties were examined in terms of their absorption and emission behavior, fluorescence quantum yields and fluorescence lifetimes. The flexible dinuclear boron complexes that are linked by a flexible carbon chain exhibited large Stokes shifts in the range from 92 nm to 115 nm in contrast to BODIPY dyes. Those properties make these complexes precious for applications in fluorescence materials. And also theoretical calculations were obtained by using Density Functional Theory (DFT) methods.
- Full Text:
- Date Issued: 2020
- Authors: Sen, Pinar , Mpeta, Lekhetho S , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186207 , vital:44473 , xlink:href="https://doi.org/10.1016/j.jlumin.2020.117262"
- Description: The synthesis of new Schiff bases and their dinuclear boron complexes is described, along with their characterization by 1H and 13C NMR, FT-IR, and UV–visible absorption spectroscopy, mass spectrometry, and EDX for elemental analysis. The optical and photophysical properties were examined in terms of their absorption and emission behavior, fluorescence quantum yields and fluorescence lifetimes. The flexible dinuclear boron complexes that are linked by a flexible carbon chain exhibited large Stokes shifts in the range from 92 nm to 115 nm in contrast to BODIPY dyes. Those properties make these complexes precious for applications in fluorescence materials. And also theoretical calculations were obtained by using Density Functional Theory (DFT) methods.
- Full Text:
- Date Issued: 2020
Chiral Modulation from Molecular to Macroscopic levels by synthetic chiral-amide-bonded porphyrin dimers
- Liang, Xu, Qin, Mingfeng, Zhang, Xiaomei, Mack, John, Soy, Rodah, Nyokong, Tebello, Zhu, Weihua
- Authors: Liang, Xu , Qin, Mingfeng , Zhang, Xiaomei , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186802 , vital:44535 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107637"
- Description: Six different nanoarchitectures were constructed by a series of synthetic bio-inspired chiral porphyrin dimers through molecular self-assembly behaviour. A plausible mechanism of chiral expression from the molecular to the macroscopic levels was investigated through an analysis of the optical spectroscopy and theoretical calculations.
- Full Text:
- Date Issued: 2019
- Authors: Liang, Xu , Qin, Mingfeng , Zhang, Xiaomei , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186802 , vital:44535 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107637"
- Description: Six different nanoarchitectures were constructed by a series of synthetic bio-inspired chiral porphyrin dimers through molecular self-assembly behaviour. A plausible mechanism of chiral expression from the molecular to the macroscopic levels was investigated through an analysis of the optical spectroscopy and theoretical calculations.
- Full Text:
- Date Issued: 2019
Effect of bromination on the optical limiting properties at 532 nm of BODIPY dyes with p-benzyloxystyryl groups at the 3, 5-positions
- Ngoy, Bokolombe P, May, Aviwe K, Mack, John, Nyokong, Tebello
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187507 , vital:44665 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.08.012"
- Description: The optical limiting (OL) properties of 3,5-di-p-benzyloxystyrylBODIPY dyes that contain both protons and bromine atoms at the 2,6-positions have been investigated by using the Z-scan technique at 532 nm on the nanosecond timescale. There is relatively weak absorbance at 532 nm under ambient light conditions, because the incorporation of p-benzyloxystyryl groups at the 3,5-positions results in a ca. 140 nm red shift of the main BODIPY spectral band to the 640–670 nm range. Reverse saturable absorbance (RSA) profiles that are consistent with an excited state absorption (ESA) mechanism involving the T1 and/or S1 states are observed in CH2Cl2 solution. Second order hyperpolarizability values of ca. 8 × 10−30 esu are obtained and this demonstrates that the dyes are potentially suitable for use in OL applications at 532 nm. There is a slight enhancement of the OL properties upon bromination, due to increased intersystem crossing to the triplet manifold, but the enhancement of the OL properties is less significant than has been observed with metal phthalocyanine complexes.
- Full Text:
- Date Issued: 2019
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187507 , vital:44665 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.08.012"
- Description: The optical limiting (OL) properties of 3,5-di-p-benzyloxystyrylBODIPY dyes that contain both protons and bromine atoms at the 2,6-positions have been investigated by using the Z-scan technique at 532 nm on the nanosecond timescale. There is relatively weak absorbance at 532 nm under ambient light conditions, because the incorporation of p-benzyloxystyryl groups at the 3,5-positions results in a ca. 140 nm red shift of the main BODIPY spectral band to the 640–670 nm range. Reverse saturable absorbance (RSA) profiles that are consistent with an excited state absorption (ESA) mechanism involving the T1 and/or S1 states are observed in CH2Cl2 solution. Second order hyperpolarizability values of ca. 8 × 10−30 esu are obtained and this demonstrates that the dyes are potentially suitable for use in OL applications at 532 nm. There is a slight enhancement of the OL properties upon bromination, due to increased intersystem crossing to the triplet manifold, but the enhancement of the OL properties is less significant than has been observed with metal phthalocyanine complexes.
- 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
Photophysical properties and photodynamic therapy activities of detonated nanodiamonds-BODIPY-phthalocyanines nanoassemblies
- Matshitse, Refilwe, Ngoy, Bokolombe P, Managa, Muthumuni, Mack, John, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Ngoy, Bokolombe P , Managa, Muthumuni , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186981 , vital:44553 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.03.007"
- Description: This work reports on the synthesis of nanoassemblies of supramolecular hybrids containing detonated nanodiamonds (DNDs) covalently linked to halogenated BODIPY (DNDs-BODIPY) by an amide bond, followed by π–π stacking of 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ) on the DNDs-BODIPY conjugate, to form nanoassembly represented as ZnTPPcQ-DNDs-BODIPY. ZnTPPcQ-DNDs-BODIPY has a higher singlet oxygen quantum yield of 0.50 in water. Therefore, the construction of a three component photodynamic therapy agent (ZnTPPcQ-DNDs-BODIPY) as a single photosentisiser improved singlet quantum yields of the Pc. Zeta potential studies of ZnTPPcQ-DNDs-BODIPY under various temperatures, concentrations and pH conditions, showed the conjugate is more stable at pHs 2, 4 and 7 and at high concentrations (50 μg/mL) and temperatures (80 °C). ZnTPPcQ-DNDs-BODIPY showed high photodynamic therapy (PDT) activity with a low MCF-7 cell viability of 21 ± 5% when compared to 31 ± 2%, 30 ± 2% and 28 ± 2% cell viability at the highest tested concentration of 50 μg/mL for DNDs, ZnTPPcQ-DND and DNDs-BODIPY, respectively.
- Full Text:
- Date Issued: 2019
- Authors: Matshitse, Refilwe , Ngoy, Bokolombe P , Managa, Muthumuni , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186981 , vital:44553 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.03.007"
- Description: This work reports on the synthesis of nanoassemblies of supramolecular hybrids containing detonated nanodiamonds (DNDs) covalently linked to halogenated BODIPY (DNDs-BODIPY) by an amide bond, followed by π–π stacking of 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ) on the DNDs-BODIPY conjugate, to form nanoassembly represented as ZnTPPcQ-DNDs-BODIPY. ZnTPPcQ-DNDs-BODIPY has a higher singlet oxygen quantum yield of 0.50 in water. Therefore, the construction of a three component photodynamic therapy agent (ZnTPPcQ-DNDs-BODIPY) as a single photosentisiser improved singlet quantum yields of the Pc. Zeta potential studies of ZnTPPcQ-DNDs-BODIPY under various temperatures, concentrations and pH conditions, showed the conjugate is more stable at pHs 2, 4 and 7 and at high concentrations (50 μg/mL) and temperatures (80 °C). ZnTPPcQ-DNDs-BODIPY showed high photodynamic therapy (PDT) activity with a low MCF-7 cell viability of 21 ± 5% when compared to 31 ± 2%, 30 ± 2% and 28 ± 2% cell viability at the highest tested concentration of 50 μg/mL for DNDs, ZnTPPcQ-DND and DNDs-BODIPY, respectively.
- Full Text:
- Date Issued: 2019
Synthesis and properties of chiral amide-bonded porphyrin dimers with various functional bridging blocks
- Zhu, Weihua, Haider, Syed Najeeb-uz-Zaman, Zhang, Honglin, Attatsi, Isaac K, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Song, Yuting, Xu, Haijun, Liang, Xu
- Authors: Zhu, Weihua , Haider, Syed Najeeb-uz-Zaman , Zhang, Honglin , Attatsi, Isaac K , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Song, Yuting , Xu, Haijun , Liang, Xu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186791 , vital:44534 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107740"
- Description: Eight porphyrin dimers with various functional bridging blocks and chiral amide-bonds were synthesized and characterized. An analysis of the spectroscopy and electrochemistry has been carried out to demonstrate that the chiral properties can be modified by changing the interchromophoric through-space coupling distance between the two porphyrin chromophores by introducing various bonding and bridging blocks.
- Full Text:
- Date Issued: 2019
- Authors: Zhu, Weihua , Haider, Syed Najeeb-uz-Zaman , Zhang, Honglin , Attatsi, Isaac K , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Song, Yuting , Xu, Haijun , Liang, Xu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186791 , vital:44534 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107740"
- Description: Eight porphyrin dimers with various functional bridging blocks and chiral amide-bonds were synthesized and characterized. An analysis of the spectroscopy and electrochemistry has been carried out to demonstrate that the chiral properties can be modified by changing the interchromophoric through-space coupling distance between the two porphyrin chromophores by introducing various bonding and bridging blocks.
- Full Text:
- Date Issued: 2019
Core-modified rubyrins with phenanthrene-fused pyrrole rings
- Yuan, Xuemei, Li, Minzhi, Meng, Ting, Mack, John, Soy, Rodah, Nyokong, Tebello, Zhu, Weihua, Xu, Haijun, Liang, Xu
- Authors: Yuan, Xuemei , Li, Minzhi , Meng, Ting , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua , Xu, Haijun , Liang, Xu
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234568 , vital:50209 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.05.045"
- Description: Three fused-ring-expanded rubyrins with modified macrocyclic core have been synthesized and characterized. A series of spectroscopic, electrochemical measurements and a set of theoretical calculations demonstrate that the core-modification of the inner core of rubyrins has a large influence on the electronic structure. Colorimetric changes are observe that demonstrate that these core-modified rubyrins could be used as selective Hg2+ ion sensors. These properties can be fine-tuned by introducing lipophilic substituents on the meso-aryl rings.
- Full Text:
- Date Issued: 2018
- Authors: Yuan, Xuemei , Li, Minzhi , Meng, Ting , Mack, John , Soy, Rodah , Nyokong, Tebello , Zhu, Weihua , Xu, Haijun , Liang, Xu
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234568 , vital:50209 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.05.045"
- Description: Three fused-ring-expanded rubyrins with modified macrocyclic core have been synthesized and characterized. A series of spectroscopic, electrochemical measurements and a set of theoretical calculations demonstrate that the core-modification of the inner core of rubyrins has a large influence on the electronic structure. Colorimetric changes are observe that demonstrate that these core-modified rubyrins could be used as selective Hg2+ ion sensors. These properties can be fine-tuned by introducing lipophilic substituents on the meso-aryl rings.
- 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