Photocatalytic desulfurization of dibenzothiophene using methoxy substituted asymmetrical zinc (II) phthalocyanines conjugated to metal tungstate nanomaterials
- Mgidlana, Sithi, Nwahara, Nnamdi, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Nwahara, Nnamdi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185760 , vital:44421 , xlink:href="https://doi.org/10.1016/j.poly.2021.115053"
- Description: We report on the syntheses of three asymmetrical zinc(II) phthalocyanine endowed with benzoic acid, phenylpropanoic acid, and phenylacetic acid units: (1), (2), and (3), respectively. Metal tungstate nanoparticles, capped with glutathione were prepared and characterized using analytical techniques. Complexes were covalently linked to nickel tungstate (NiWO4) and bismuth tungstate (Bi2WO6) through an amide bond. The complexes and the conjugates with nanomaterial were evaluated for singlet oxygen generating ability. Complexes 1–2 and their conjugates generate higher singlet oxygen compared to 3 and its corresponding conjugates. The conjugates show degradation of dibenzothiophene (DBT) in fuel with shorter half-lives and greater initial rate values compared to phthalocyanines alone.
- Full Text:
- Date Issued: 2021
- Authors: Mgidlana, Sithi , Nwahara, Nnamdi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185760 , vital:44421 , xlink:href="https://doi.org/10.1016/j.poly.2021.115053"
- Description: We report on the syntheses of three asymmetrical zinc(II) phthalocyanine endowed with benzoic acid, phenylpropanoic acid, and phenylacetic acid units: (1), (2), and (3), respectively. Metal tungstate nanoparticles, capped with glutathione were prepared and characterized using analytical techniques. Complexes were covalently linked to nickel tungstate (NiWO4) and bismuth tungstate (Bi2WO6) through an amide bond. The complexes and the conjugates with nanomaterial were evaluated for singlet oxygen generating ability. Complexes 1–2 and their conjugates generate higher singlet oxygen compared to 3 and its corresponding conjugates. The conjugates show degradation of dibenzothiophene (DBT) in fuel with shorter half-lives and greater initial rate values compared to phthalocyanines alone.
- Full Text:
- Date Issued: 2021
Click chemistry electrode modification using 4-ethynylbenzyl substituted cobalt phthalocyanine for applications in electrocatalysis
- Mpeta, Lekhetho S, Fomo, Gertrude, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Fomo, Gertrude , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187626 , vital:44681 , xlink:href="• https://doi.org/10.1080/00958972.2018.1466118"
- Description: In this work, we report on the synthesis and applications of a new cobalt tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyanine (3) for the detection of hydrazine. The glassy carbon electrode (GCE) was first grafted through diazotization, providing the GCE surface layer with azide groups. Thereafter, the 1,3-dipolar cycloaddition reaction, catalyzed by a copper(I) catalyst was used to “click” complex 3 to the grafted surface of GCE. The new platform was then characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). This work shows that 3 is an effective sensor with sensitivity of 91.5 μA mM−1 and limit of detection of 3.28 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2018
- Authors: Mpeta, Lekhetho S , Fomo, Gertrude , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187626 , vital:44681 , xlink:href="• https://doi.org/10.1080/00958972.2018.1466118"
- Description: In this work, we report on the synthesis and applications of a new cobalt tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyanine (3) for the detection of hydrazine. The glassy carbon electrode (GCE) was first grafted through diazotization, providing the GCE surface layer with azide groups. Thereafter, the 1,3-dipolar cycloaddition reaction, catalyzed by a copper(I) catalyst was used to “click” complex 3 to the grafted surface of GCE. The new platform was then characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). This work shows that 3 is an effective sensor with sensitivity of 91.5 μA mM−1 and limit of detection of 3.28 μM which is a great improvement compared to other reported sensors for this analyte.
- Full Text:
- Date Issued: 2018
Improving singlet oxygen generating abilities of phthalocyanines
- Nwahara, Nnamdi, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188943 , vital:44800 , xlink:href="https://doi.org/10.1080/00958972.2017.1313975"
- Description: Glutathione-capped graphene quantum dots (GQDs@GSH) were covalently linked to folic acid (FA). Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was then adsorbed on the GQDs@GSH-FA conjugate to form GQDs@GSH-FA/ClAlTSPc or on GQDs@GSH and pristine GQDs alone to form GQDs@GSH/ClAlTSPc and GQDs/ClAlTSPc, respectively. We report for the first time on the photophysicochemical behavior of the resulting nanoconjugates. The fluorescence quantum yields of pristine GQDs, GQDS@GSH, or GQDs@GSH-FA conjugate were quenched upon non-covalent interaction (π–π) with ClAlTSPc. There was an increase in triplet quantum yields from 0.38 for ClAlTSPc alone to 0.60, 0.75, and 0.73 when ClAlTSPc was linked to pristine GQDs, GQDs@GSH, and GQDs@GSH-FA, respectively. The singlet oxygen quantum yields also increased from 0.37 for ClAlTSPc alone to 0.42 (for ClALTSPc with pristine GQDs), 0.52 (for ClAlTSPc with GQDs@GSH), and 0.54 (for ClAlTSPc with GQDs@GSH-FA). Thus, the present work may lead to a new generation of carbon-based nanomaterial photodynamic therapy agents with overall performance superior to conventional agents in terms of singlet oxygen generation, water dispersibility, and biocompatibility.
- Full Text:
- Date Issued: 2017
- Authors: Nwahara, Nnamdi , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188943 , vital:44800 , xlink:href="https://doi.org/10.1080/00958972.2017.1313975"
- Description: Glutathione-capped graphene quantum dots (GQDs@GSH) were covalently linked to folic acid (FA). Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was then adsorbed on the GQDs@GSH-FA conjugate to form GQDs@GSH-FA/ClAlTSPc or on GQDs@GSH and pristine GQDs alone to form GQDs@GSH/ClAlTSPc and GQDs/ClAlTSPc, respectively. We report for the first time on the photophysicochemical behavior of the resulting nanoconjugates. The fluorescence quantum yields of pristine GQDs, GQDS@GSH, or GQDs@GSH-FA conjugate were quenched upon non-covalent interaction (π–π) with ClAlTSPc. There was an increase in triplet quantum yields from 0.38 for ClAlTSPc alone to 0.60, 0.75, and 0.73 when ClAlTSPc was linked to pristine GQDs, GQDs@GSH, and GQDs@GSH-FA, respectively. The singlet oxygen quantum yields also increased from 0.37 for ClAlTSPc alone to 0.42 (for ClALTSPc with pristine GQDs), 0.52 (for ClAlTSPc with GQDs@GSH), and 0.54 (for ClAlTSPc with GQDs@GSH-FA). Thus, the present work may lead to a new generation of carbon-based nanomaterial photodynamic therapy agents with overall performance superior to conventional agents in terms of singlet oxygen generation, water dispersibility, and biocompatibility.
- Full Text:
- Date Issued: 2017
A comparative physicochemical study of unsymmetrical indium phthalocyanines in the presence of magnetic nanoparticles or quantum dots
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
Probing electrochemical and electrocatalytic properties of cobalt (II) and manganese (III) octakis (hexylthio) phthalocyanine as self-assembled monolayers
- Mashazi, Philani N, Antunes, Edith M, Nyokong, Tebello
- Authors: Mashazi, Philani N , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249115 , vital:51779 , xlink:href="https://doi.org/10.1142/S108842461000277X"
- Description: New peripherally (β) and non-peripherally (α) substituted metal octakis(hexylthio)phthalocyanines (β- and α-MOcHexTPc) containing cobalt and manganese as metal centers were synthesized. Their characterization using electrochemical methods showed that these complexes exhibit several redox processes at E1/2 (mV vs. Ag∣AgCl) = 380 (212) (I), 1140 (864) (II), -450 (-460) (III) and -1170 (-1304) (IV) for β- (α-) CoOcHexTPc. These redox processes were assigned to CoIIIPc-2/CoIIPc-2 (I), CoIIIPc-1/CoIIIPc-2 (II), CoIIPc-2/CoIPc-2 (III) and CoIPc-2/CoIPc-3 (IV) using spectroelectrochemistry. For the β- (α-) MnOcHexTPc complex the redox processes were observed at E1/2 (mV vs. Ag∣AgCl) = -20 (5) (I), -530 (-640) (II) and -1270 (-1380) (III) and were assigned to MnIIIPc-2/MnIIPc-2 (I), MnIIPc-2/MnIIPc-3 (II) and MnIIPc-3/MnIIPc-4 (III). Electrochemical and microscopic characterization using AFM showed that the self-assembled monolayers (SAMs) are formed on the gold surface using these complexes. The electrochemical characterization showed the blocking of the Faradaic processes at SAMs modified electrodes and these reactions are well-known to easily occur at unmodified gold electrodes. The AFM characterization showed an increase in surface roughness upon modifying the gold surface with MOcHexTPc SAMs, further confirming the presence of the monolayers on the gold surface. The MOcHexTPc SAMs were investigated for their electrocatalytic application towards H2O2 detection. The MOcHexTPc SAMs modified gold electrodes gave excellent currents for H2O2 detection. The observed H2O2 electrocatalytic reduction peaks were close to where the metal redox processes from the MOcHexTPc occurred, showing the involvement of the metal redox processes in the electrocatalytic mediation reactions.
- Full Text:
- Date Issued: 2010
- Authors: Mashazi, Philani N , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249115 , vital:51779 , xlink:href="https://doi.org/10.1142/S108842461000277X"
- Description: New peripherally (β) and non-peripherally (α) substituted metal octakis(hexylthio)phthalocyanines (β- and α-MOcHexTPc) containing cobalt and manganese as metal centers were synthesized. Their characterization using electrochemical methods showed that these complexes exhibit several redox processes at E1/2 (mV vs. Ag∣AgCl) = 380 (212) (I), 1140 (864) (II), -450 (-460) (III) and -1170 (-1304) (IV) for β- (α-) CoOcHexTPc. These redox processes were assigned to CoIIIPc-2/CoIIPc-2 (I), CoIIIPc-1/CoIIIPc-2 (II), CoIIPc-2/CoIPc-2 (III) and CoIPc-2/CoIPc-3 (IV) using spectroelectrochemistry. For the β- (α-) MnOcHexTPc complex the redox processes were observed at E1/2 (mV vs. Ag∣AgCl) = -20 (5) (I), -530 (-640) (II) and -1270 (-1380) (III) and were assigned to MnIIIPc-2/MnIIPc-2 (I), MnIIPc-2/MnIIPc-3 (II) and MnIIPc-3/MnIIPc-4 (III). Electrochemical and microscopic characterization using AFM showed that the self-assembled monolayers (SAMs) are formed on the gold surface using these complexes. The electrochemical characterization showed the blocking of the Faradaic processes at SAMs modified electrodes and these reactions are well-known to easily occur at unmodified gold electrodes. The AFM characterization showed an increase in surface roughness upon modifying the gold surface with MOcHexTPc SAMs, further confirming the presence of the monolayers on the gold surface. The MOcHexTPc SAMs were investigated for their electrocatalytic application towards H2O2 detection. The MOcHexTPc SAMs modified gold electrodes gave excellent currents for H2O2 detection. The observed H2O2 electrocatalytic reduction peaks were close to where the metal redox processes from the MOcHexTPc occurred, showing the involvement of the metal redox processes in the electrocatalytic mediation reactions.
- Full Text:
- Date Issued: 2010
Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis
- Nyokong, Tebello, Bedioui, Fethi
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283826 , vital:55994 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283826 , vital:55994 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis
- Nyokong, Tebello, Bedioui, Fethi
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283851 , vital:55996 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
- Authors: Nyokong, Tebello , Bedioui, Fethi
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283851 , vital:55996 , xlink:href="https://doi.org/10.1142/S1088424606000454"
- Description: In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
- Full Text:
- Date Issued: 2006
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