List of Titles

Characterization of phthalocyanine functionalized quantum dots by dynamic light scattering, laser Doppler, and capillary electrophoresis

- Ramírez-García, Gonzalo, Oluwole, David O, Nxele, Siphesihle Robin, d’Orlyé, Fanny, Nyokong, Tebello, Bedioui, Fethi, Varenne, Anne

Authors: Ramírez-García, Gonzalo , Oluwole, David O , Nxele, Siphesihle Robin , d’Orlyé, Fanny , Nyokong, Tebello , Bedioui, Fethi , Varenne, Anne
Date: 2017
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/238184 , vital:50595 , xlink:href="https://doi.org/10.1007/s00216-016-0120-x"
Description: In this work, we characterized different phtalocyanine-capped core/shell/shell quantum dots (QDs) in terms of stability, ζ-potential, and size at various pH and ionic strengths, by means of capillary electrophoresis (CE), and compared these results to the ones obtained by laser Doppler electrophoresis (LDE) and dynamic light scattering (DLS). The effect of the phthalocyanine metallic center (Zn, Al, or In), the number (one or four), and nature of substituents (carboxyphenoxy- or sulfonated-) of functionalization on the phthalocyanine physicochemical properties were evaluated. Whereas QDs capped with zinc mono-carboxyphenoxy-phtalocyanine (ZnMCPPc-QDs) remained aggregated in the whole analyzed pH range, even at low ionic strength, QDs capped with zinc tetracarboxyphenoxy phtalocyanine (ZnTPPc-QDs) were easily dispersed in buffers at pH equal to or higher than 7.4. QDs capped with aluminum tetrasulfonated phthalocyanine (AlTSPPc-QDs) and indium tetracarboxyphenoxy phthalocyanines (InTCPPc-QDs) were stable in aqueous suspension only at pH higher than 9.0 due to the presence of functional groups bound to the metallic center of the phthalocyanine. The ζ-potential values determined by CE for all the samples decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiological relevant solutions and thereby, its usefulness for improving their design and applications for photodynamic therapy.
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Date Issued: 2017

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Surface patterning using scanning electrochemical microscopy to locally trigger a “click” chemistry reaction

- Quinton, Damien, Maringa, Audacity, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi

Authors: Quinton, Damien , Maringa, Audacity , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
Date: 2013
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/241805 , vital:50971 , xlink:href="https://doi.org/10.1016/j.elecom.2013.03.021"
Description: We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈ 10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈ 75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates.
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Date Issued: 2013

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4-Azidoaniline-based electropolymer as a building block for functionalisation of conductive surfaces

- Coates, Megan, Elamari, Hichem, Girard, Christian, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi

Authors: Coates, Megan , Elamari, Hichem , Girard, Christian , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
Date: 2012
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/244404 , vital:51254 , xlink:href="https://doi.org/10.1016/j.jelechem.2012.01.001"
Description: We propose in this work to compare three approaches using 4-azidoaniline combined with “click” chemistry and electrochemistry to anchor ferrocene moieties at glassy carbon surfaces. The immobilisation of a newly synthesised molecule, 4-(4-ferrocenyl-1H-1,2,3-triazol-1-yl)aniline, through direct electropolymerisation or via in situ diazotization followed by electrografting is studied by analysing the samples by XPS and electrochemistry.
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Date Issued: 2012

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Layer by Layer Electrode Surface Functionalisation Using Carbon Nanotubes, Electrochemical Grafting of Azide‐Alkyne Functions and Click Chemistry

- Coates, Megan, Griveau, Sophie, Bedioui, Fethi, Nyokong, Tebello

Authors: Coates, Megan , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
Date: 2012
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/243509 , vital:51159 , xlink:href="https://doi.org/10.1002/elan.201200240"
Description: Ferrocene was covalently bonded to a layer of adsorbed single-walled carbon nanotubes on a glassy carbon electrode surface using electrochemical grafting and click chemistry. Grafting of the 4-azidobenzenediazonium salt onto the surface was accomplished by electrochemical reduction. The surface-bound azide groups, with the use of a copper(I) catalyst, were reacted with ethynylferrocene to form covalent 1,2,3-triazole bonds by click chemistry. This layer by layer construction of the electrode surface results in stable electrodes by combining good electrical conductivity and increased surface area of the nanotubes with the versatility of the Sharpless click reaction.
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Date Issued: 2012

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Surface electrochemistry : structured electrode, synthesis, and characterization

- Bedioui, Fethi, Nyokong, Tebello, Zagal, Jose H

Authors: Bedioui, Fethi , Nyokong, Tebello , Zagal, Jose H
Date: 2012
Language: English
Type: Article
Identifier: vital:6567 , http://hdl.handle.net/10962/d1004126 , http://dx.doi.org/10.1155/2012/405825
Description: From introduction: The aim of this special issue is to show, through recent updated significant examples, how the electrochemical techniques allow the unique characterization of specific properties of micro- and nanostructured materials that offer varied possibilities of uses and the preparation of specific types of ordered materials that take advantage of electrochemical synthetic methods such as structuring nanosized wires and dots, to cite only two examples.
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Date Issued: 2012

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Cyclic voltammetry and spectroelectrochemistry of a novel manganese phthalocyanine substituted with hexynyl groups

- Quinton, Damien, Antunes, Edith M, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi

Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
Date: 2011
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
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Date Issued: 2011

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Microelectrochemical patterning of gold surfaces using 4-azidobenzenediazonium and scanning electrochemical microscopy

- Coates, Megan, Cabet, Eva, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi

Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
Date: 2011
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
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Date Issued: 2011

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Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions

- Zagal, José H, Griveau, Sophie J, Silva, Francisco, Nyokong, Tebello, Bedioui, Fethi

Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
Date: 2010
Language: English
Type: text , Article
Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
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Date Issued: 2010

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Electro-catalyzed oxidation of reduced glutathione and 2-mercaptoethanol by cobalt phthalocyanine-containing screen printed graphite electrodes

- Sehlotho, Nthapo, Griveau, Sophie, Ruillé, Nadine, Boujtita, Mohammed, Nyokong, Tebello, Bedioui, Fethi

Authors: Sehlotho, Nthapo , Griveau, Sophie , Ruillé, Nadine , Boujtita, Mohammed , Nyokong, Tebello , Bedioui, Fethi
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/265935 , vital:53902 , xlink:href="https://doi.org/10.1016/j.msec.2007.10.054"
Description: Electro-catalytic behavior of screen printed graphite electrodes modified with cobalt phthalocyanine (CoPc) towards the oxidation of reduced glutathione (GSH) and 2-mercaptoethanol (2-ME) is reported. We find, by using cyclic voltammetry, that the oxidation of 2-ME occurs at 0.2 V vs Ag/AgCl and − 0.3 vs Ag/AgCl V at pH = 7 and pH = 13, respectively and that of GSH occurs at 0.4 V vs Ag/AgCl and 0.0 V vs Ag/AgCl at pH = 7 and 13, respectively. The electro-catalytic activity depends on the method of electrode modification and the amount of catalyst incorporated in the ink used to fabricate the SPCEs. The highest activity was obtained with electrodes prepared with 2.5% (w:w) of CoPc.
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Date Issued: 2008

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Electrochemical Characterization of Self-Assembled Monolayer of a Novel Manganese Tetrabenzylthio-Substituted Phthalocyanine and Its Use in Nitrite Oxidation

- Matemadombo, Fungisai, Griveau, Sophie, Bedioui, Fethi, Nyokong, Tebello

Authors: Matemadombo, Fungisai , Griveau, Sophie , Bedioui, Fethi , Nyokong, Tebello
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/265950 , vital:53903 , xlink:href="https://doi.org/10.1002/elan.200804269"
Description: Manganese phthalocyanine MnPc(SPh)4 has been synthesized and used to form self assembled monolayers on gold electrodes. The well packed SAM monolayer was characterized by analyzing the blocking of a number of Faradic processes by cyclic voltammetry, evaluating the electrical characteristics of the modified electrode by electrochemical impedance and imaging the modified surface by electrochemical scanning microscopy. Finally, MnPc(SPh)4-SAM modified electrode displayed an electrocatalytic behavior toward the oxidation of nitrite.
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Date Issued: 2008

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Tuning the redox properties of Co-N4 macrocyclic complexes for the catalytic electrooxidation of glucose

- Villagra, Evelyn, Bedioui, Fethi, Nyokong, Tebello, Canales, J Carlos, Sancy, Mamie, Páez, Maritza A, Costamagna, Juan, Zagal, Jose H

Authors: Villagra, Evelyn , Bedioui, Fethi , Nyokong, Tebello , Canales, J Carlos , Sancy, Mamie , Páez, Maritza A , Costamagna, Juan , Zagal, Jose H
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/268675 , vital:54221 , xlink:href="https://doi.org/10.1016/j.electacta.2008.02.006"
Description: Graphite electrodes modified with four different cobalt N4 macrocyclics, namely Co tetrapentapyridinophthalocyanine, (CoTPenPyrPc), Co tetrapyridinoporphyrazine (CoTPyPz), Co octa(hydroxyethylthio)phthalocyanine (CoOEHTPc) and Co tetranitrophthalocyanine (CoTNPc) exhibit catalytic activity for the oxidation of glucose in alkaline media. The purpose of this work is to establish correlations between the catalytic activity of these complexes and their redox potential. The activity of the different modified electrodes was tested by linear voltammetry under hydrodynamic conditions using the rotating disk technique. Tafel plots constructed from mass-transport corrected currents give slopes ranging from 0.080 to 0.160 V/decade for the different catalysts which suggests that a first one-electron step is rate controlling with the symmetry of the energy barrier depending on the nature of the ligand of the Co complex. A plot of log I versus the Co(II)/(I) formal potential gives a volcano curve that also includes catalysts studied previously. This illustrates the concept that the formal potential of the catalyst needs to be tuned to a certain value for achieving maximum activity. A theoretical interpretation of these results is given in terms of Langmuir isotherms for the adsorption of glucose on the Co sites of the surface-confined metal complexes.
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Date Issued: 2008

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Volcano correlations for the reactivity of surface-confined cobalt N4-macrocyclics for the electrocatalytic oxidation of 2-mercaptoacetate

- Claußen, Jan A, Ochoa, Gonzalo, Páez, Maritza, Costamagno, Juan, Gulppi, Miguel, Nyokong, Tebello, Bedioui, Fethi, Zagal, José H

Authors: Claußen, Jan A , Ochoa, Gonzalo , Páez, Maritza , Costamagno, Juan , Gulppi, Miguel , Nyokong, Tebello , Bedioui, Fethi , Zagal, José H
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/268688 , vital:54222 , xlink:href="https://doi.org/10.1007/s10008-007-0336-y"
Description: We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin larger than Co–tetrasulfonatotetraphenylporphyrin larger than Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine. Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation for the interaction of the thiol with the active site.
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Date Issued: 2008

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Cobalt Phthalocyanine Molecular Electrode for the Electrochemical Investigation of the Release of Glutathione upon Copper-Catalyzed Decomposition of S-Nitrosoglutathione

- Sehlotho, Nthapo, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi

Authors: Sehlotho, Nthapo , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/281201 , vital:55701 , xlink:href="https://doi.org/10.1002/elan.200603656"
Description: Decomposition of S-nitrosoglutathione (GSNO) in phosphate buffer solution at physiological pH 7.4 in the presence of cuprous ion as a catalyst and sodium borohydride as a reducing agent is analyzed by observing the transient apparition of reduced glutathione GSH through its electrooxidation. Transient formation of GSH, upon decomposition of 1 mM GSNO in presence of 0.025 mM Cu(NO3)2 and 1 mM NaBH4 was detected by using an ordinary pyrolytic graphite electrode modified with an adsorbed monolayer of cobalt phthalocyanine at 0 V vs. SCE.
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Date Issued: 2007

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Tuning the redox properties of metalloporphyrin-and metallophthalocyanine-based molecular electrodes for the highest electrocatalytic activity in the oxidation of thiols

- Bedioui, Fethi, Griveau, Sophie, Nyokong, Tebello, Appleby, A John, Caro, Claudia A, Gulppi, Miguel, Ochoa, Gonzalo, Zagal, José H

Authors: Bedioui, Fethi , Griveau, Sophie , Nyokong, Tebello , Appleby, A John , Caro, Claudia A , Gulppi, Miguel , Ochoa, Gonzalo , Zagal, José H
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/283988 , vital:56009 , xlink:href="https://doi.org/10.1039/B618767F"
Description: In this work we discuss different approaches for achieving electrodes modified with N4 macrocyclic complexes for the catalysis of the electrochemical oxidation of thiols. These approaches involve adsorption, electropolymerization and molecular anchoring using self assembled monolayers. We also discuss the parameters that determine the reactivity of these complexes. Catalytic activity is associated with the nature of the central metal, redox potentials and Hammett parameters of substituents on the ligand. Correlations between catalytic activity (log i at constant E) and the redox potential of catalysts for complexes of Cr, Mn, Fe, Co, Ni and Cu are linear with an increase of activity for more positive redox potentials. For a great variety complexes bearing the same metal center (Co) correlations between log i and Eo′ of the Co(II)/Co(I) couple have the shape of an unsymmetric volcano. This indicates that the potential of the Co(II)/Co(I) couple can be tuned using the appropiate ligand to achieve maximum catalytic activity. Maximum activity probably corresponds to a ΔG of adsorption of the thiol on the Co center equal to zero, and to a coverage of active sites by the thiol equal to 0.5.
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Date Issued: 2007

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Electrocatalysis of oxidation of 2-mercaptoethanol, L-cysteine and reduced glutathione by adsorbed and electrodeposited cobalt tetra phenoxypyrrole and tetra ethoxythiophene substituted phthalocyanines

- Sehlotho, Nthapo, Nyokong, Tebello, Zagal, Jose H, Bedioui, Fethi

Authors: Sehlotho, Nthapo , Nyokong, Tebello , Zagal, Jose H , Bedioui, Fethi
Date: 2006
Language: English
Type: Article
Identifier: vital:6593 , http://hdl.handle.net/10962/d1004342
Description: Catalytic activity of cobalt tetra ethoxythiophene and cobalt tetra phenoxypyrrole phthalocyanine complexes towards oxidation of 2-mercaptoethanol, L-cysteine and reduced glutathione is reported. It was found that the activity of the complexes depends on the substitution of the phthalocyanine ring, pH, film thickness and method of electrode modification. The high electrocatalytic activity obtained with adsorbed complexes in alkaline medium clearly demonstrates the necessity of modifying bare carbon electrodes to endow them with the desired behaviour.
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Date Issued: 2006

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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.
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Date Issued: 2006

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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.
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Date Issued: 2006

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UV-Visible and Electrochemical Monitoring of Carbon Monoxide Release by Donor Complexes to Myoglobin Solutions and to Electrodes Modified with Films Containing Hemin

- Obirai, Joseph C, Hamadi, Sara, Ithurbide, Aurélie, Wartelle, Corinne, Nyokong, Tebello, Zagal, José, Top, Siden, Bedioui, Fethi

Authors: Obirai, Joseph C , Hamadi, Sara , Ithurbide, Aurélie , Wartelle, Corinne , Nyokong, Tebello , Zagal, José , Top, Siden , Bedioui, Fethi
Date: 2006
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/283906 , vital:56001 , xlink:href="https://doi.org/10.1002/elan.200603571"
Description: This study reports on the evaluation of the CO donating behavior of tricarbonyl dichloro ruthenium(II) dimer ([Ru(CO)3Cl2]2) and 1,3-dimethoxyphenyl tricarbonyl chromium (C6H3(MeO)2Cr(CO)3) complex by UV-visible technique and electrochemical technique. The CO release was monitored by following the modifications of the UV-visible features of MbFe(II) in phosphate buffer solution and the redox features of reduced Hemin, HmFe(II), confined at the surface of a vitreous carbon electrode. In the latter case, the interaction between the hemin-modified electrode and the released CO was seen through the observation of an increase of the reduction current related to the FeIII/FeII redox process of the immobilized porphyrin. While the ruthenium-based complex, ([Ru(CO)3Cl2]2), depended on the presence of Fe(II) species to release CO, it was found that the chromium-based complex released spontaneously CO. This was facilitated by illuminating and/or simple stirring of the solution containing the complex.
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Date Issued: 2006

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Electro-oxidation of phenol and its derivatives on poly-Ni (OH) TPhPyPc modified vitreous carbon electrodes

- Obirai, Joseph, Bedioui, Fethi, Nyokong, Tebello

Authors: Obirai, Joseph , Bedioui, Fethi , Nyokong, Tebello
Date: 2005
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/289353 , vital:56625 , xlink:href="https://doi.org/10.1016/j.jelechem.2004.11.006"
Description: The electrochemical oxidation of phenol and its derivatives using poly-nickel hydroxy tetraphenoxypyrrolephthalocyanine (poly-Ni(OH)TPhPyPc) modified vitreous carbon electrodes are described. The films were formed by the electro-transformation of the electropolymerized pyrrole-substituted phenoxyphthalocyanine poly-NiTPhPyPc modified electrode in aqueous 0.1 M NaOH solution. The poly-Ni(OH)TPhPyPc films showed better stability and resistance to electrode fouling compared to poly-NiTPhPyPc and unmodified electrodes. The resistance to surface fouling and stability can be attributed to the structure of the ring substituent on the phthalocyanine macrocycle and to the particular O–Ni–O bridged architecture of the nickel phthalocyanine film.
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Date Issued: 2005

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Electropolymerized Pyrrole-Substituted Manganese Phthalocyanine Films for the Electroassisted Biomimetic Catalytic Reduction of Molecular Oxygen

- Rodrigues, Nazaré Pereira, Obirai, Joe, Nyokong, Tebello, Bedioui, Fethi

Authors: Rodrigues, Nazaré Pereira , Obirai, Joe , Nyokong, Tebello , Bedioui, Fethi
Date: 2005
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/289372 , vital:56626 , xlink:href="https://doi.org/10.1002/elan.200403064"
Description: We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole-manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic voltammetry and UV-visible spectrophotometry on optically transparent electrodes. The obtained results demonstrate the probable existence of the key-steps responsible for the suggested formation of the highly reactive manganese oxo intermediate.
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Date Issued: 2005

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