Nanohybrid electrocatalyst based on cobalt phthalocyanine-carbon nanotube-reduced graphene oxide for ultrasensitive detection of glucose in human saliva
- Adeniyi, Omotayo, Nwahara, Nnamdi, Mwanza, Daniel, Nyokong, Tebello, Mashazi, Philani N
- Authors: Adeniyi, Omotayo , Nwahara, Nnamdi , Mwanza, Daniel , Nyokong, Tebello , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231356 , vital:49880 , xlink:href="https://doi.org/10.1016/j.snb.2021.130723"
- Description: The current diabetes management systems require collecting blood samples via an invasive and painful finger pricking leading to the formation of callus, scarring and loss of sensibility to patients due to continuous monitoring. Therefore, a non-invasive and painless method of determining glucose levels would be desirable to diabetes patients who need constant monitoring. Saliva glucose measurement is a non-invasive alternative for diabetes management. A highly sensitive, stable, and selective non-enzymatic electrochemical sensor that can accurately quantify saliva glucose is required. A single-walled carbon nanotube/reduced graphene oxide/cobalt phthalocyanines nanohybrid modified glassy carbon electrode (GCE-SWCNT/rGO/CoPc) has been fabricated for the non-enzymatic determination of glucose in human saliva. The SWCNT/rGO/CoPc was characterized using various spectroscopic, microscopic, and electrochemical techniques. The synergistic effect between SWCNT, rGO, and CoPc facilitated excellent electron transfer process that improved the sensor sensitivity. The GCE-SWCNT/rGO/CoPc sensor exhibited two linear responses in the 0.30 μM to 0.50 mM and 0.50–5.0 mM glucose concentration ranges, and the detection limit was 0.12 μM. The sensor had an excellent saliva glucose detection sensitivity of 992.4 μA·mM−1·cm−2 and high specificity for glucose in the presence of other coexisting analytes. In addition, it showed good storage stability, reusability, and a fast response time of about 1.2 s. The GCE-SWCNT/rGO/CoPc nanohybrid electrode showed excellent potential for developing accurate, non-invasive, and painless glucose sensing.
- Full Text:
- Date Issued: 2021
- Authors: Adeniyi, Omotayo , Nwahara, Nnamdi , Mwanza, Daniel , Nyokong, Tebello , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231356 , vital:49880 , xlink:href="https://doi.org/10.1016/j.snb.2021.130723"
- Description: The current diabetes management systems require collecting blood samples via an invasive and painful finger pricking leading to the formation of callus, scarring and loss of sensibility to patients due to continuous monitoring. Therefore, a non-invasive and painless method of determining glucose levels would be desirable to diabetes patients who need constant monitoring. Saliva glucose measurement is a non-invasive alternative for diabetes management. A highly sensitive, stable, and selective non-enzymatic electrochemical sensor that can accurately quantify saliva glucose is required. A single-walled carbon nanotube/reduced graphene oxide/cobalt phthalocyanines nanohybrid modified glassy carbon electrode (GCE-SWCNT/rGO/CoPc) has been fabricated for the non-enzymatic determination of glucose in human saliva. The SWCNT/rGO/CoPc was characterized using various spectroscopic, microscopic, and electrochemical techniques. The synergistic effect between SWCNT, rGO, and CoPc facilitated excellent electron transfer process that improved the sensor sensitivity. The GCE-SWCNT/rGO/CoPc sensor exhibited two linear responses in the 0.30 μM to 0.50 mM and 0.50–5.0 mM glucose concentration ranges, and the detection limit was 0.12 μM. The sensor had an excellent saliva glucose detection sensitivity of 992.4 μA·mM−1·cm−2 and high specificity for glucose in the presence of other coexisting analytes. In addition, it showed good storage stability, reusability, and a fast response time of about 1.2 s. The GCE-SWCNT/rGO/CoPc nanohybrid electrode showed excellent potential for developing accurate, non-invasive, and painless glucose sensing.
- Full Text:
- Date Issued: 2021
Voltammetric characterisation of the self-assembled monolayers (SAMs) of benzyl-and dodecyl-mercapto tetra substituted metallophthalocyanines complexes
- Agboola, Bolade, Westbroek, Philippe, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Westbroek, Philippe , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281414 , vital:55723 , xlink:href="https://doi.org/10.1016/j.elecom.2006.08.047"
- Description: Voltammetric characterisations of cobalt, iron, manganese, nickel and zinc phthalocyanine complexes tetra substituted with benzyl- and dodecyl-mercapto ring substituents and immobilisation on gold electrodes via the self-assembling technique are presented. The self-assembled films are stable and showed blocking characteristics towards the following Faradaic processes; gold surface oxidation, under potential deposition of copper and solution redox chemistry of [Fe(H2O)6 3+ ]/[Fe(H2O)6 2+ ]. The solution chemistry of [Fe(CN)6]−3/[Fe(CN)6]−4 redox process was used to study the orientation of the CoPcs-SAMs and this revealed a possible deviation from flat orientation of the complexes on the gold electrodes when the SAM formation times were greater than 24 h. For SAM formation time at 24 and 48 h, CoTDMPc-SAM showed more inhibition of the [Fe(CN)6]−3/[Fe(CN)6]−4 redox process than the CoTBMPc-SAM counterpart, indicating more blocking characteristics of the dodecylmercapto ring substituents compared to the benzylmercapto counterpart. To avoid SAM desorption, the potential application should be limited to −0.2 to +0.8 V vs. Ag∣AgCl (NaCl, sat’d) in acidic and neutral pH.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Westbroek, Philippe , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281414 , vital:55723 , xlink:href="https://doi.org/10.1016/j.elecom.2006.08.047"
- Description: Voltammetric characterisations of cobalt, iron, manganese, nickel and zinc phthalocyanine complexes tetra substituted with benzyl- and dodecyl-mercapto ring substituents and immobilisation on gold electrodes via the self-assembling technique are presented. The self-assembled films are stable and showed blocking characteristics towards the following Faradaic processes; gold surface oxidation, under potential deposition of copper and solution redox chemistry of [Fe(H2O)6 3+ ]/[Fe(H2O)6 2+ ]. The solution chemistry of [Fe(CN)6]−3/[Fe(CN)6]−4 redox process was used to study the orientation of the CoPcs-SAMs and this revealed a possible deviation from flat orientation of the complexes on the gold electrodes when the SAM formation times were greater than 24 h. For SAM formation time at 24 and 48 h, CoTDMPc-SAM showed more inhibition of the [Fe(CN)6]−3/[Fe(CN)6]−4 redox process than the CoTBMPc-SAM counterpart, indicating more blocking characteristics of the dodecylmercapto ring substituents compared to the benzylmercapto counterpart. To avoid SAM desorption, the potential application should be limited to −0.2 to +0.8 V vs. Ag∣AgCl (NaCl, sat’d) in acidic and neutral pH.
- Full Text:
- Date Issued: 2007
Comparative electrooxidation of nitrite by electrodeposited Co (II), Fe (II) and Mn (III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines on gold electrodes
- Agboola, Bolade, Nyokong, Tebello
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281212 , vital:55702 , xlink:href="https://doi.org/10.1016/j.aca.2007.01.031"
- Description: This work reports on the electrooxidation of nitrite using Co(II), Fe(II) and Mn(III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines electrodeposited onto a gold electrode. Good catalytic activity (in terms of lowering overpotential) was obtained for these molecules when compared to previously reported MPc catalysts. The catalytic current was found to vary linearly with nitrite concentration in the range employed in this work (0.1–1 mM) and high sensitivities ranging from 6.9 to 9.9 μA mM−1 were observed for all the modified electrodes.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281212 , vital:55702 , xlink:href="https://doi.org/10.1016/j.aca.2007.01.031"
- Description: This work reports on the electrooxidation of nitrite using Co(II), Fe(II) and Mn(III) tetrakis (benzylmercapto) and tetrakis (dodecylmercapto) phthalocyanines electrodeposited onto a gold electrode. Good catalytic activity (in terms of lowering overpotential) was obtained for these molecules when compared to previously reported MPc catalysts. The catalytic current was found to vary linearly with nitrite concentration in the range employed in this work (0.1–1 mM) and high sensitivities ranging from 6.9 to 9.9 μA mM−1 were observed for all the modified electrodes.
- Full Text:
- Date Issued: 2007
Comparative efficiency of immobilized non-transition metal phthalocyanine photosensitizers for the visible light transformation of chlorophenols
- Agboola, Bolade, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
Hydrogen peroxide oxidation of 2-chlorophenol and 2, 4, 5-trichlorophenol catalyzed by monomeric and aggregated cobalt tetrasulfophthalocyanine
- Agboola, Bolade, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289249 , vital:56612 , xlink:href="https://doi.org/10.1016/j.molcata.2004.10.041"
- Description: Cobalt tetrasulfophthalocyanine (CoTSPc) was used to catalyze the oxidation of 2-chlorophenol (2-CP) and 2,4,5-trichlorophenol (TCP) using hydrogen peroxide (H2O2) as the oxidant. This CoTSPc catalyzed hydrogen peroxide oxidation of chlorophenols resulted in the formation of different types of oxidation products depending on the solvent conditions. In water/methanol conditions (where CoTSPc is mainly monomeric, and unionized forms of the phenols), phenol and hydroquinone were the main oxidation products, while in phosphate buffer solutions (pH 7 and 10 for TCP and 2-CP, respectively, where CoTSPc is mainly aggregated, and ionized forms of the phenols), benzoquinone was the main product. In contrast to CoTSPc, other MTSPc complexes studied (AlTSPc, CuTSPc and NiTSPc) exhibited no detectable catalytic effect on the oxidation of chlorophenols under the experimental conditions employed, thus proving the effect of the central metal ions on efficient catalysis of chlorophenol. Reaction pathways are proposed based on the relative time of oxidation products formation.
- Full Text:
- Date Issued: 2005
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289249 , vital:56612 , xlink:href="https://doi.org/10.1016/j.molcata.2004.10.041"
- Description: Cobalt tetrasulfophthalocyanine (CoTSPc) was used to catalyze the oxidation of 2-chlorophenol (2-CP) and 2,4,5-trichlorophenol (TCP) using hydrogen peroxide (H2O2) as the oxidant. This CoTSPc catalyzed hydrogen peroxide oxidation of chlorophenols resulted in the formation of different types of oxidation products depending on the solvent conditions. In water/methanol conditions (where CoTSPc is mainly monomeric, and unionized forms of the phenols), phenol and hydroquinone were the main oxidation products, while in phosphate buffer solutions (pH 7 and 10 for TCP and 2-CP, respectively, where CoTSPc is mainly aggregated, and ionized forms of the phenols), benzoquinone was the main product. In contrast to CoTSPc, other MTSPc complexes studied (AlTSPc, CuTSPc and NiTSPc) exhibited no detectable catalytic effect on the oxidation of chlorophenols under the experimental conditions employed, thus proving the effect of the central metal ions on efficient catalysis of chlorophenol. Reaction pathways are proposed based on the relative time of oxidation products formation.
- Full Text:
- Date Issued: 2005
Comparative electrooxidation of sulphite by self-assembled monolayers (SAMs) of Co (II), Fe (II), Ni (II) and Mn (III) tetrakis benzylmercapto and dodecylmercapto metallophthalocyanines complexes on gold electrodes
- Agboola, Bolade, Nyokong, Tebello
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281223 , vital:55703 , xlink:href="https://doi.org/10.1016/j.talanta.2006.11.042"
- Description: This work reports on the use of Co(II), Fe(II), Mn(III) and Ni(II) tetrakis benzylmercapto and dodecylmercapto phthalocyanine complexes for gold electrode modification for electrooxidation of sulphite ions. The complexes were successfully used to modify gold electrodes by self-assembled monolayer (SAM) technique. The self-assembled films are stable and showed blocking characteristics towards the following Faradaic processes; gold surface oxidation, underpotential deposition (UPD) of copper and solution redox chemistry of [Fe(H2O)63+]/[Fe(H2O)62+]. All the modified electrodes showed improved catalytic activities than the unmodified gold electrode towards sulphite ion electrooxidation with all the modified electrodes exhibiting high resistance to electrode surface passivation. Better catalytic performance were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak, while the NiPcs which did not show metal based redox reaction performed less. The catalytic current was found to be linear with sulphite ion concentration in the concentration range employed in this work (0.1–1 mM) and sensitivities ranging from 1.68 to 2.96 μA/mM were observed for all the modified electrodes. Mechanisms of the catalytic oxidation of sulphite ions are proposed.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281223 , vital:55703 , xlink:href="https://doi.org/10.1016/j.talanta.2006.11.042"
- Description: This work reports on the use of Co(II), Fe(II), Mn(III) and Ni(II) tetrakis benzylmercapto and dodecylmercapto phthalocyanine complexes for gold electrode modification for electrooxidation of sulphite ions. The complexes were successfully used to modify gold electrodes by self-assembled monolayer (SAM) technique. The self-assembled films are stable and showed blocking characteristics towards the following Faradaic processes; gold surface oxidation, underpotential deposition (UPD) of copper and solution redox chemistry of [Fe(H2O)63+]/[Fe(H2O)62+]. All the modified electrodes showed improved catalytic activities than the unmodified gold electrode towards sulphite ion electrooxidation with all the modified electrodes exhibiting high resistance to electrode surface passivation. Better catalytic performance were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak, while the NiPcs which did not show metal based redox reaction performed less. The catalytic current was found to be linear with sulphite ion concentration in the concentration range employed in this work (0.1–1 mM) and sensitivities ranging from 1.68 to 2.96 μA/mM were observed for all the modified electrodes. Mechanisms of the catalytic oxidation of sulphite ions are proposed.
- Full Text:
- Date Issued: 2007
Synthesis and electrochemical properties of benzyl-mercapto and dodecyl-mercapto tetrasubstituted manganese phthalocyanine complexes
- Agboola, Bolade, Ozoemena, Kenneth I, Westbroek, Philippe, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Westbroek, Philippe , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281321 , vital:55713 , xlink:href="https://doi.org/10.1016/j.electacta.2006.09.002"
- Description: Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mercapto) phthalocyanine (MnTDMPc) complexes were synthesized and their spectral and electrochemical properties are reported. Cyclic voltammetric data showed three reversible to quasi-reversible and two irreversible redox processes for both complexes. Ring substituents influenced the positions of both oxidation and reduction redox couples. Spectroelectrochemistry confirmed the first two reductions to be due to MnIIIPc2−/MnIIPc2− and MnIIPc3−/MnIIPc2− processes. The first example of a formation of self-assembled monolayers (SAMs) using thiol substituted MnPc complexes is presented, the SAMs were found to show blocking characteristics towards some faradaic reactions.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Westbroek, Philippe , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281321 , vital:55713 , xlink:href="https://doi.org/10.1016/j.electacta.2006.09.002"
- Description: Manganese tetrakis (benzyl-mercapto) phthalocyanine (MnTBMPc) and manganese tetrakis (dodecyl-mercapto) phthalocyanine (MnTDMPc) complexes were synthesized and their spectral and electrochemical properties are reported. Cyclic voltammetric data showed three reversible to quasi-reversible and two irreversible redox processes for both complexes. Ring substituents influenced the positions of both oxidation and reduction redox couples. Spectroelectrochemistry confirmed the first two reductions to be due to MnIIIPc2−/MnIIPc2− and MnIIPc3−/MnIIPc2− processes. The first example of a formation of self-assembled monolayers (SAMs) using thiol substituted MnPc complexes is presented, the SAMs were found to show blocking characteristics towards some faradaic reactions.
- Full Text:
- Date Issued: 2007
Electrocatalytic oxidation of chlorophenols by electropolymerised nickel (II) tetrakis benzylmercapto and dodecylmercapto metallophthalocyanines complexes on gold electrodes
- Agboola, Bolade, Nyokong, Tebello
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281247 , vital:55705 , xlink:href="https://doi.org/10.1016/j.electacta.2007.02.017"
- Description: This work reports on the use of nickel(II) tetrakis benzylmercapto (NiTBMPc) and dodecylmercapto (NiTDMPc) metallophthalocyanine complexes films on gold electrodes for the electrochemical oxidation of 4-chlorophenol (4-CP) and 2,4,5-trichlorophenol (TCP). Both NiTBMPc and NiTDMPc complexes were successfully deposited on gold electrodes by electropolymerisation. The films were electro-transformed in aqueous 0.1 M NaOH solution to the ‘O–Ni–O oxo’ bridged form. For both complexes, films with different thickness were prepared and characterised by electrochemical impedance and UV–vis (on indium tin oxide) spectroscopies and the results showed typical behaviour for modified electrodes with increasing charge transfer resistance values (Rp) with polymer thickness. The poly-Ni(OH)NiPcs showed better catalytic activity than their poly-NiPcs counterparts.
- Full Text:
- Date Issued: 2007
- Authors: Agboola, Bolade , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281247 , vital:55705 , xlink:href="https://doi.org/10.1016/j.electacta.2007.02.017"
- Description: This work reports on the use of nickel(II) tetrakis benzylmercapto (NiTBMPc) and dodecylmercapto (NiTDMPc) metallophthalocyanine complexes films on gold electrodes for the electrochemical oxidation of 4-chlorophenol (4-CP) and 2,4,5-trichlorophenol (TCP). Both NiTBMPc and NiTDMPc complexes were successfully deposited on gold electrodes by electropolymerisation. The films were electro-transformed in aqueous 0.1 M NaOH solution to the ‘O–Ni–O oxo’ bridged form. For both complexes, films with different thickness were prepared and characterised by electrochemical impedance and UV–vis (on indium tin oxide) spectroscopies and the results showed typical behaviour for modified electrodes with increasing charge transfer resistance values (Rp) with polymer thickness. The poly-Ni(OH)NiPcs showed better catalytic activity than their poly-NiPcs counterparts.
- Full Text:
- Date Issued: 2007
Tuning the physico-electrochemical properties of novel cobalt (II) octa [(3, 5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs
- Agboola, Bolade O, Ozoemena, Kenneth I, Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261692 , vital:53435 , xlink:href="https://doi.org/10.1016/j.carbon.2009.10.023"
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode.
- Full Text:
- Date Issued: 2010
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261692 , vital:53435 , xlink:href="https://doi.org/10.1016/j.carbon.2009.10.023"
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode.
- Full Text:
- Date Issued: 2010
Tuning the physico-electrochemical properties of novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs
- Agboola, Bolade Oyeyinka, Ozoemena, Kenneth I., Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Agboola, Bolade Oyeyinka , Ozoemena, Kenneth I. , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Language: English
- Type: Article
- Identifier: vital:7238 , http://hdl.handle.net/10962/d1019689
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode. , Original publication is available at http://dx.doi.org/doi:10.1016/j.carbon.2009.10.023
- Full Text: false
- Authors: Agboola, Bolade Oyeyinka , Ozoemena, Kenneth I. , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Language: English
- Type: Article
- Identifier: vital:7238 , http://hdl.handle.net/10962/d1019689
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode. , Original publication is available at http://dx.doi.org/doi:10.1016/j.carbon.2009.10.023
- Full Text: false
Characterization of polymeric film of a new manganese phthalocyanine complex octa-substituted with 2-diethylaminoethanethiol, and its use for the electrochemical detection of bentazon
- Akinbulu, Isaac A, Nyokong, Tebello
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262568 , vital:53534 , xlink:href="https://doi.org/10.1016/j.electacta.2009.07.074"
- Description: Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to MnIIIPc−1/MnIIIPc−2, MnIIIPc−2/MnIIPc−2 and MnIIPc−2/MnIIPc−3 species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, Rct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10−7 M.
- Full Text:
- Date Issued: 2009
Syntheses and investigation of the effects of position and nature of substituent on the spectral, electrochemical and spectroelectrochemical properties of new cobalt phthalocyanine complexes
- Akinbulu, Isaac A, Nyokong, Tebello
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261677 , vital:53434 , xlink:href="https://doi.org/10.1016/j.poly.2010.01.004"
- Description: The syntheses of new cobalt phthalocyanine (CoPc) complexes, tetra-substituted with diethylaminoethanethio at the peripheral (complex 3a) and non-peripheral (complex 3b) positions, and with benzylmercapto at the non-peripheral position (complex 5), are reported. The effects of the nature and position of substituent on the spectral, electrochemical and spectroelectrochemical properties of these complexes are investigated. Solution electrochemistry of complex 3a showed three distinctly resolved redox processes attributed to CoIIIPc−2/CoIIPc−2 (E½ = +0.64 V versus Ag|AgCl), CoIIPc−2/CoIPc−2 (E½ = −0.24 V versus Ag|AgCl) and CoIPc−2/CoIPc−3 (E½ = −1.26 V versus Ag|AgCl) species. No ring oxidation was observed in complex 3a. Complex 3b showed both ring-based oxidation, attributed to CoIIIPc−1/CoIIIPc−2 species (Ep = +0.86 V versus Ag|AgCl), and ring-based reduction associated with CoIPc−2/CoIPc−3 species (E½ = −1.46 V versus Ag|AgCl), with the normal metal-based redox processes in CoPc complexes: CoIIIPc−2/CoIIPc−2 (Ep = +0.41 V versus Ag|AgCl) and CoIIPc−2/CoIPc−2 (E½ = −0.38 V versus Ag|AgCl). Solution electrochemistry of complex 5 showed the same type and number of species observed in complex 3a: CoIIIPc−2/CoIIPc−2 (Ep = +0.59 V versus Ag|AgCl), CoIIPc−2/CoIPc−2 (E½ = −0.26 V versus Ag|AgCl) and CoIPc−2/CoIPc−3 (E½ = −1.39 V versus Ag|AgCl) species. These processes were confirmed using spectroelectrochemistry.
- Full Text:
- Date Issued: 2010
- Authors: Akinbulu, Isaac A , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261677 , vital:53434 , xlink:href="https://doi.org/10.1016/j.poly.2010.01.004"
- Description: The syntheses of new cobalt phthalocyanine (CoPc) complexes, tetra-substituted with diethylaminoethanethio at the peripheral (complex 3a) and non-peripheral (complex 3b) positions, and with benzylmercapto at the non-peripheral position (complex 5), are reported. The effects of the nature and position of substituent on the spectral, electrochemical and spectroelectrochemical properties of these complexes are investigated. Solution electrochemistry of complex 3a showed three distinctly resolved redox processes attributed to CoIIIPc−2/CoIIPc−2 (E½ = +0.64 V versus Ag|AgCl), CoIIPc−2/CoIPc−2 (E½ = −0.24 V versus Ag|AgCl) and CoIPc−2/CoIPc−3 (E½ = −1.26 V versus Ag|AgCl) species. No ring oxidation was observed in complex 3a. Complex 3b showed both ring-based oxidation, attributed to CoIIIPc−1/CoIIIPc−2 species (Ep = +0.86 V versus Ag|AgCl), and ring-based reduction associated with CoIPc−2/CoIPc−3 species (E½ = −1.46 V versus Ag|AgCl), with the normal metal-based redox processes in CoPc complexes: CoIIIPc−2/CoIIPc−2 (Ep = +0.41 V versus Ag|AgCl) and CoIIPc−2/CoIPc−2 (E½ = −0.38 V versus Ag|AgCl). Solution electrochemistry of complex 5 showed the same type and number of species observed in complex 3a: CoIIIPc−2/CoIIPc−2 (Ep = +0.59 V versus Ag|AgCl), CoIIPc−2/CoIPc−2 (E½ = −0.26 V versus Ag|AgCl) and CoIPc−2/CoIPc−3 (E½ = −1.39 V versus Ag|AgCl) species. These processes were confirmed using spectroelectrochemistry.
- Full Text:
- Date Issued: 2010
The effects of point of substitution on the formation of manganese phthalocyanine-based molecular materials
- Akinbulu, Isaac Adebayo, Khene, Samson, Nyokong, Tebello
- Authors: Akinbulu, Isaac Adebayo , Khene, Samson , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249103 , vital:51778 , xlink:href="https://doi.org/10.1016/j.tsf.2010.08.145"
- Description: Molecular films of manganese phthalocyanine (MnPc) complexes, tetra-substituted with 2-diethylaminoethanethio at the peripheral (Mn(OAc)-β-TDEAETPc, 1) and non-peripheral (Mn(OAc)-α-TDEAETPc, 2) positions were formed on glassy carbon electrode by electropolymerization and electrodeposition respectively. Atomic force microscopy images confirmed the presence of the films and revealed significant morphological differences. The films exhibited an electrocatalytic activity towards the oxidation of the insecticide, bendiocarb. Hydrodynamic technique, using rotating disc electrode voltammetry, was used to investigate the kinetics of electro-oxidation of the insecticide. Morphological differences of the films significantly influenced kinetic parameters. Values of Tafel slopes, obtained from Tafel plots, suggested that catalysis of bendiocarb occurred via outer sphere mechanism.
- Full Text:
- Date Issued: 2010
- Authors: Akinbulu, Isaac Adebayo , Khene, Samson , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249103 , vital:51778 , xlink:href="https://doi.org/10.1016/j.tsf.2010.08.145"
- Description: Molecular films of manganese phthalocyanine (MnPc) complexes, tetra-substituted with 2-diethylaminoethanethio at the peripheral (Mn(OAc)-β-TDEAETPc, 1) and non-peripheral (Mn(OAc)-α-TDEAETPc, 2) positions were formed on glassy carbon electrode by electropolymerization and electrodeposition respectively. Atomic force microscopy images confirmed the presence of the films and revealed significant morphological differences. The films exhibited an electrocatalytic activity towards the oxidation of the insecticide, bendiocarb. Hydrodynamic technique, using rotating disc electrode voltammetry, was used to investigate the kinetics of electro-oxidation of the insecticide. Morphological differences of the films significantly influenced kinetic parameters. Values of Tafel slopes, obtained from Tafel plots, suggested that catalysis of bendiocarb occurred via outer sphere mechanism.
- Full Text:
- Date Issued: 2010
The effects of point of substitution on the electrochemical behavior of new manganese phthalocyanines, tetra-substituted with diethylaminoethanethiol
- Akinbulu, Isaac Adebayo, Nyokong, Tebello
- Authors: Akinbulu, Isaac Adebayo , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249137 , vital:51781 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.003"
- Description: The syntheses and comparative studies of the spectral, voltammetry and spectroelectrochemical properties of new manganese phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the peripheral (complex 3a) and non-peripheral positions (complex 3b) are reported. Solution electrochemistry of complex 3a showed quasi-reversible metal-based (MnIIIPc−2/MnIIPc−2, E1/2 = −0.07 V vs. Ag|AgCl) and ring-based (MnIIPc−2/MnIIPc−3, E1/2 = −0.78 V vs. Ag|AgCl) reductions, but no ring-based oxidation. However, complex 3b showed weak irreversible ring-oxidation signal (Ep = +0.86 vs. Ag|AgCl). Reversible metal-based (MnIIIPc−2/MnIIPc−2, E1/2 = −0.04 V vs. Ag|AgCl) and ring-based (MnIIPc−2/MnIIPc−3, E1/2 = −0.68 V vs. Ag|AgCl) reductions were also observed for complex 3b. Spectroelectrochemistry was used to confirm these processes. Reduction process involving the metal (MnIIIPc−2/MnIIPc−2) was associated with the formation of manganese μ-oxo complex in complex 3a.
- Full Text:
- Date Issued: 2010
- Authors: Akinbulu, Isaac Adebayo , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249137 , vital:51781 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.003"
- Description: The syntheses and comparative studies of the spectral, voltammetry and spectroelectrochemical properties of new manganese phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the peripheral (complex 3a) and non-peripheral positions (complex 3b) are reported. Solution electrochemistry of complex 3a showed quasi-reversible metal-based (MnIIIPc−2/MnIIPc−2, E1/2 = −0.07 V vs. Ag|AgCl) and ring-based (MnIIPc−2/MnIIPc−3, E1/2 = −0.78 V vs. Ag|AgCl) reductions, but no ring-based oxidation. However, complex 3b showed weak irreversible ring-oxidation signal (Ep = +0.86 vs. Ag|AgCl). Reversible metal-based (MnIIIPc−2/MnIIPc−2, E1/2 = −0.04 V vs. Ag|AgCl) and ring-based (MnIIPc−2/MnIIPc−3, E1/2 = −0.68 V vs. Ag|AgCl) reductions were also observed for complex 3b. Spectroelectrochemistry was used to confirm these processes. Reduction process involving the metal (MnIIIPc−2/MnIIPc−2) was associated with the formation of manganese μ-oxo complex in complex 3a.
- Full Text:
- Date Issued: 2010
Formation, surface characterization, and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese, iron, and cobalt benzylthio phthalocyanine complexes
- Akinbulu, Isaac Adebayo, Ozoemena, Kenneth Iyke, Nyokong, Tebello
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
- Authors: Akinbulu, Isaac Adebayo , Ozoemena, Kenneth Iyke , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247163 , vital:51552 , xlink:href="https://doi.org/10.1007/s10008-010-1243-1"
- Description: Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10−2 cm s−1 on the SAM film with the best current signal (SAM-2).
- Full Text:
- Date Issued: 2011
Photophysical and photochemical parameters of octakis (benzylthio) phthalocyaninato zinc, aluminium and tin
- Akpe, Victor, Brismar, Hjalmar, Nyokong, Tebello, Osadebe, Patience Ogoamak
- Authors: Akpe, Victor , Brismar, Hjalmar , Nyokong, Tebello , Osadebe, Patience Ogoamak
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248472 , vital:51689 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.08.033"
- Description: This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)8 (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, RsI of the complexes tend to increase as the refractive index, nD, and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, ϕd measurements of these compounds show that they are highly photostable, ϕd (0.03–0.33 × 10−5). The triplet quantum yield, ϕT (0.40–0.53) and the triplet lifetime, τT (610–810 μs) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency, SΔ, is relatively high for all the molecules (0.74–0.90).
- Full Text:
- Date Issued: 2010
- Authors: Akpe, Victor , Brismar, Hjalmar , Nyokong, Tebello , Osadebe, Patience Ogoamak
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248472 , vital:51689 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.08.033"
- Description: This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)8 (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, RsI of the complexes tend to increase as the refractive index, nD, and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, ϕd measurements of these compounds show that they are highly photostable, ϕd (0.03–0.33 × 10−5). The triplet quantum yield, ϕT (0.40–0.53) and the triplet lifetime, τT (610–810 μs) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency, SΔ, is relatively high for all the molecules (0.74–0.90).
- Full Text:
- Date Issued: 2010
The synthesis and characterisation of magnetic nanoparticles and their interaction with a zinc phthalocyanine
- Antunes, Edith M, Rapulenyane, Nomasonto, Ledwaba, Mpho, Litwinski, Christian, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Antunes, Edith M , Rapulenyane, Nomasonto , Ledwaba, Mpho , Litwinski, Christian , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242111 , vital:51002 , xlink:href="https://doi.org/10.1016/j.inoche.2012.12.010"
- Description: A variety of nanoparticles (NPs), including FePt nanoparticles with Fe as the shell (2) or Pt as the shell (3), Pt NPs (4), and FePd (5) were synthesised, characterised and their effect on a zinc phthalocyanine (1) tetra-substituted with a pyridyl-oxy substituent studied using UV/Vis and fluorescence spectroscopy (including time correlated single photon counting, TCSPC). The nanoparticles were characterised using a number of techniques including UV/Vis and inductively coupled plasma-optical emission (ICP-OES) spectroscopies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and electron paramagnetic resonance (EPR) spectroscopy. Nanocomposites (NCs, 6,7) where the ZnPc (1) was used as the stabiliser, instead of oleic acid and or oleylamine, were also synthesised and characterised.
- Full Text:
- Date Issued: 2013
- Authors: Antunes, Edith M , Rapulenyane, Nomasonto , Ledwaba, Mpho , Litwinski, Christian , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242111 , vital:51002 , xlink:href="https://doi.org/10.1016/j.inoche.2012.12.010"
- Description: A variety of nanoparticles (NPs), including FePt nanoparticles with Fe as the shell (2) or Pt as the shell (3), Pt NPs (4), and FePd (5) were synthesised, characterised and their effect on a zinc phthalocyanine (1) tetra-substituted with a pyridyl-oxy substituent studied using UV/Vis and fluorescence spectroscopy (including time correlated single photon counting, TCSPC). The nanoparticles were characterised using a number of techniques including UV/Vis and inductively coupled plasma-optical emission (ICP-OES) spectroscopies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and electron paramagnetic resonance (EPR) spectroscopy. Nanocomposites (NCs, 6,7) where the ZnPc (1) was used as the stabiliser, instead of oleic acid and or oleylamine, were also synthesised and characterised.
- Full Text:
- Date Issued: 2013
Synthesis and photophysical properties of peripherally and non-peripherally mercaptopyridine substituted metal free, Mg (II) and Al (III) phthalocyanines
- Arslanoğlu, Yasin, Idowu, Mopelela, Nyokong, Tebello
- Authors: Arslanoğlu, Yasin , Idowu, Mopelela , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243248 , vital:51131 , xlink:href="https://doi.org/10.1016/j.saa.2012.04.004"
- Description: The syntheses and photophysical properties of metallophthalocyanines containing Mg2+ and Al3+ as central metal ions and their unmetallated derivative (complexes 3–8) tetra- substituted at the non-peripheral (α) and peripheral (β) positions with 2-mercaptopyridine are reported. The trends in triplet and fluorescence quantum yields are described for these compounds. The complexes exhibited relatively high triplet quantum yields (ΦT) ranging from 0.33 to 0.54 and fluorescence quantum yields (ΦF) ranging from 0.02 to 0.29. Triplet state lifetimes of the complexes were long ranging from 120 to 460 μs, indicating a potential use of these complexes as photosensitizers.
- Full Text:
- Date Issued: 2012
- Authors: Arslanoğlu, Yasin , Idowu, Mopelela , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243248 , vital:51131 , xlink:href="https://doi.org/10.1016/j.saa.2012.04.004"
- Description: The syntheses and photophysical properties of metallophthalocyanines containing Mg2+ and Al3+ as central metal ions and their unmetallated derivative (complexes 3–8) tetra- substituted at the non-peripheral (α) and peripheral (β) positions with 2-mercaptopyridine are reported. The trends in triplet and fluorescence quantum yields are described for these compounds. The complexes exhibited relatively high triplet quantum yields (ΦT) ranging from 0.33 to 0.54 and fluorescence quantum yields (ΦF) ranging from 0.02 to 0.29. Triplet state lifetimes of the complexes were long ranging from 120 to 460 μs, indicating a potential use of these complexes as photosensitizers.
- Full Text:
- Date Issued: 2012
Synthesis and photophysical studies of monocarboxy phthalocyanines containing quaternizable groups
- Arslanoğlu, Yasin, Nyokong, Tebello
- Authors: Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246992 , vital:51535 , xlink:href="https://doi.org/10.1016/j.poly.2011.08.009"
- Description: This work reports on the synthesis and photophysical properties of novel unsymmetrically substituted monocarboxy magnesium (MgPc, 3), aluminum (ClAlPc, 4) and unmetallated (H2Pc, 5) phthalocyanines. Magnesium phthalocyanine (3) was converted into water soluble quaternized derivative (QMgPc, 6) by reaction with methyl iodide. The synthesized phthalocyanines were characterized by IR, UV–Vis, NMR, mass spectrometry and elemental analyses. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy. Triplet quantum yields ranged from 0.37 to 0.40 and triplet lifetimes from 110 to 140 μs in DMSO.
- Full Text:
- Date Issued: 2011
- Authors: Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246992 , vital:51535 , xlink:href="https://doi.org/10.1016/j.poly.2011.08.009"
- Description: This work reports on the synthesis and photophysical properties of novel unsymmetrically substituted monocarboxy magnesium (MgPc, 3), aluminum (ClAlPc, 4) and unmetallated (H2Pc, 5) phthalocyanines. Magnesium phthalocyanine (3) was converted into water soluble quaternized derivative (QMgPc, 6) by reaction with methyl iodide. The synthesized phthalocyanines were characterized by IR, UV–Vis, NMR, mass spectrometry and elemental analyses. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy. Triplet quantum yields ranged from 0.37 to 0.40 and triplet lifetimes from 110 to 140 μs in DMSO.
- Full Text:
- Date Issued: 2011
Synthesis and photodynamic potential of tetra-and octa-triethyleneoxysulfonyl substituted zinc phthalocyanines
- Atilla, Devrim, Savdan, Nil, Durmus, Mahmut, Gürek, Ayşe Gül, Khan, Tania, Rück, Angelika, Walt, Heinrich, Nyokong, Tebello, Ahsen, Vefa
- Authors: Atilla, Devrim , Savdan, Nil , Durmus, Mahmut , Gürek, Ayşe Gül , Khan, Tania , Rück, Angelika , Walt, Heinrich , Nyokong, Tebello , Ahsen, Vefa
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281342 , vital:55715 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.022"
- Description: Synthesis of the water soluble zinc phthalocyanines (3, 4) obtained from the phthalonitriles substituted with oligo(ethyleneoxy)thia groups are described. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, including HSQC, HMBC and COSY bidimensional correlation techniques, electronic spectroscopy and mass spectra. The aggregation behaviour of the phthalocyanine compounds (3, 4) was investigated using UV–vis spectroscopy in dimethylsulphoxide. Photochemical and photophysical measurements were conducted on oligo(ethyleneoxy)thia appended zinc phthalocyanines. General trends are described for quantum yields of photodegredation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds. The phototoxicity against cancer cells of the new compounds was investigated during several in vitro experiments. The dye-sensitized photooxidation of 1,3-diphenylisobenzofurane via 1O2 was studied in dimethylsulphoxide.
- Full Text:
- Date Issued: 2007
- Authors: Atilla, Devrim , Savdan, Nil , Durmus, Mahmut , Gürek, Ayşe Gül , Khan, Tania , Rück, Angelika , Walt, Heinrich , Nyokong, Tebello , Ahsen, Vefa
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281342 , vital:55715 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.022"
- Description: Synthesis of the water soluble zinc phthalocyanines (3, 4) obtained from the phthalonitriles substituted with oligo(ethyleneoxy)thia groups are described. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, including HSQC, HMBC and COSY bidimensional correlation techniques, electronic spectroscopy and mass spectra. The aggregation behaviour of the phthalocyanine compounds (3, 4) was investigated using UV–vis spectroscopy in dimethylsulphoxide. Photochemical and photophysical measurements were conducted on oligo(ethyleneoxy)thia appended zinc phthalocyanines. General trends are described for quantum yields of photodegredation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds. The phototoxicity against cancer cells of the new compounds was investigated during several in vitro experiments. The dye-sensitized photooxidation of 1,3-diphenylisobenzofurane via 1O2 was studied in dimethylsulphoxide.
- Full Text:
- Date Issued: 2007