List of Titles

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.
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Date Issued: 2007

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Shakespeare's Victorian Stage: performing history in the theatre of Charles Kean, Richard W. Schoch: book review

- Wright, Laurence

Authors: Wright, Laurence
Date: 2004
Language: English
Type: text , article
Identifier: vital:7050 , http://hdl.handle.net/10962/d1007393 , http://hdl.handle.net/10520/EJC48030
Description: preprint , This book is a primarily a study of Charles Kean’s productions of Shakespeare’s English chronicle plays at the Princess’s Theatre between 1852 and 1859, a period crucial to the development of ideas of English nationalism. Schoch focuses on these particular stagings as more than drama; as performances of nineteenth century theories of history and historical representation. His project operates under the aegis of the so-called ‘linguistic turn’ in cultural theory, and is suspicious of neo-marxian fundamentalism.
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Date Issued: 2004

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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.
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Date Issued: 2007

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The thirtieth anniversary of the Soweto uprisings: reading the shadow in Sam Nzima's iconic photograph of Hector Pieterson

- Simbao, Ruth K

Authors: Simbao, Ruth K
Date: 2007
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/147536 , vital:38647 , https://doi.org/10.1162/afar.2007.40.2.52
Description: This haunting photograph (Fig. 1) from the 1976 Soweto Uprisings in South Africa is often referred to as the single most important photograph to emerge from the struggle against apartheid (Purtilo 1999:22). According to South African film director Feizel Mamdoo, there are particular moments in history that are defined by photographic, celluloid, or television images, such as the world famous photograph of the Saigon girl, naked and burning from napalm (Worsdale 1998; see also Richards 2001). He argues that the iconic photograph by Sam Nzima depicting Hector Pieterson being carried in the arms of Mbuyisa Makhubu, with his distraught sister Antionette1 running alongside, is comparable in the way that “it marks history, both social and personal” (Worsdale 1998).
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Date Issued: 2007

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Electrocatalytic activity of arylthio tetra-substituted oxotitanium (IV) phthalocyanines towards the oxidation of nitrite

- Tau, Prudence, Nyokong, Tebello

Authors: Tau, Prudence , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/281234 , vital:55704 , xlink:href="https://doi.org/10.1016/j.electacta.2006.12.059"
Description: This paper investigates the catalytic activities of arylthio substituted oxotitanium phthalocyanine (OTiPc) complexes that are immobilized on the glassy carbon electrode by electropolymerization, towards the oxidation of nitrite. The complexes are peripherally and non-peripherally substituted with phenylthio and benzylthio groups, namely 1a, 1b, 2a and 2b. All the modified electrodes exhibited improved electrocatalytic oxidation of nitrite than the unmodified electrodes by a two-electron mechanism producing nitrate ions. Catalytic currents are enhanced and nitrite overpotential reduced to ∼0.60 V. Kinetic parameters are determined for all complexes and a mechanism is proposed.
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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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More media for Southern Africa?: the place of politics, economics and convergence in developing media density

- Berger, Guy

Authors: Berger, Guy
Date: 2007
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/147825 , vital:38676 , https://0-doi.org.wam.seals.ac.za/10.1080/02560240485310041
Description: In line with global trends, media in Southern Africa in the past decade has been moving slowly towards mergers, partnerships and multi-platform publishing. Driven by politics and facilitated by technology, the process has had to confront the difficulty of establishing viable economic models, the lack of regional integration within Southern African countries, and what is sometimes a difficult political environment. Markets remain largely national or local and economically weak. Print media faces huge hurdles. Broadcast media density is improving, partly through noncommercial mechanisms. News websites are understaffed, lacking in viable survival strategies and skills, and are incompletely integrated with parent media platforms. Economic pressures, however, are likely to force Southern African media operations into greater synergies in search of survival. The various convergences entailed may increase media density.
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Date Issued: 2007

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Excited state dynamics of zinc and aluminum phthalocyanine carboxylates

- Idowu, Mopelola, Ogunsipe, Abimbola, Nyokong, Tebello

Authors: Idowu, Mopelola , Ogunsipe, Abimbola , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/271228 , vital:54523 , xlink:href="https://doi.org/10.1016/j.saa.2007.01.025"
Description: Photophysical parameters for zinc and aluminium tetracarboxylphthalocyanines (ZnTCPc and AlTCPc, respectively) and their octacarboxy substituted counterparts (ZnOCPc and AlOCPc) were studied. Data for the fluorescence quenching of the complexes by benzoquinone (BQ) were treated using the Stern–Volmer analysis, and the quenching was found to follow a diffusion-controlled (dynamic) bimolecular mechanism. Theoretical values of bimolecular rate constant for complex-BQ interactions were determined using the Stokes–Einstein–Smoluchowski model; and the values, together with the Stern–Volmer quenching constants were used in calculating the fluorescence lifetimes of the complexes. The thermodynamics of the MPc-BQ interaction, in terms of solvent reorientation energy is also discussed.
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Date Issued: 2007

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Photophysical and photochemical properties of zinc and aluminum phthalocyanines in the presence of magnetic fluid

- Idowu, Mopelola, Nyokong, Tebello

Authors: Idowu, Mopelola , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/281298 , vital:55710 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.12.013"
Description: The effect of magnetic fluid (MF) on the photophysical and photochemical parameters of zinc and aluminum phthalocyanines are reported. The complexes studied are zinc (II) phthalocyanine (ZnPc), chloroaluminum phthalocyanine ((Cl)AlPc) and tetrasulfonated aluminum phthalocyanine ((Cl)AlTSPc). The parameters are studied in dimethylsulfoxide (DMSO) for all complexes and also in aqueous media for (Cl)AlTSPc. The triplet lifetimes for (Cl)AlTSPc and ZnPc decreased while the triplet quantum yields increased in the presence of MF. For (Cl)AlPc, the triplet lifetimes were found to increase with decrease in laser energy while there was photoreduction to the Pc−3 species. Singlet oxygen and photodegradation quantum yields decreased in the presence of MF, suggesting quenching.
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Date Issued: 2007

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Comparative photocatalytic efficiency of oxotitanium (IV) phthalocyanines for the oxidation of 1-hexene

- Tau, Prudence, Nyokong, Tebello

Authors: Tau, Prudence , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/271193 , vital:54520 , xlink:href="https://doi.org/10.1016/j.molcata.2007.04.005"
Description: The comparative photocatalytic activities of aryloxy and arylthio tetrasubstituted oxotitanium(IV) phthalocyanine complexes for the oxidation of 1-hexene in DCM are reported for the first time. The singlet oxygen quantum yield, photostability and photocatalytic properties are investigated. The catalysts effectively catalyse 1-hexene to 1,2-epoxyhexane and 1-hexen-3-ol as major and minor products respectively. The photooxidation products are formed via two reaction mechanisms, namely via singlet oxygen (Type II) and radical (Type I) reaction pathways. These are also dependent on the singlet oxygen quantum yields and photostabilities of the phthalocyanines. Complex 1a that is peripherally substituted with phenoxy groups exhibited the best activity in terms of overall performance.
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Date Issued: 2007

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Photophysical and photochemical studies of long chain-substituted zinc phthalocyanines

- Durmus, Mahmut, Ahsen, Vefa, Nyokong, Tebello

Authors: Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/281310 , vital:55711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2006.08.025"
Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy)-substituted zinc phthalocyanines (1, 2). General trends are described for quantum yields of photodegradation, fluorescence yields, triplet lifetimes and triplet quantum yields as well as singlet quantum yields of these compounds in dimethylformamide (DMF) and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2) are reported.
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Date Issued: 2007

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Lazarus in the Constitutional Court: an exhumation of the exceptio doli generalis

- Glover, Graham B

Authors: Glover, Graham B
Date: 2007
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/70678 , vital:29688 , https://hdl.handle.net/10520/EJC53775
Description: A landmark moment in the history of South African contract law was the emphatic interment of the exceptio doli generalis by Joubert JA in Bank of Lisbon and South Africa v De Ornelas 1988 (3) SA580 (A). Throughout most of the twentieth century, the exceptio doli generalis had been viewed as an equitable defence that allowed a defendant to resist a claim for performance under a contract when there was something unconscionable about the plaintiff's seeking to enforce the contract (or a clause thereof) in the specific circumstances of that case (see A J Kerr Principles of the Law of Contract 6 ed (2002) 637ff; P J Aronstam 'Unconscionable contracts: The South African solution?' (1979) 42 THRHR 21; P van Warmelo 'Exceptio doli' 1981 De Jure 202).
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Date Issued: 2007

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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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Realistic idealism

- Tabensky, Pedro

Authors: Tabensky, Pedro
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/305700 , vital:58605 , xlink:href="https://doi.org/10.3167/th.2007.5411306"
Description: Realists found in International Relations (IR) circles explicitly assign relatively minor importance to ethical ideals in their analyses of the international political domain, although a robust ethical ideal of sorts, implicitly for the most part qua ethical ideal, does guide their analysis of the international arena. For them, the key to order in the international arena is the balance of power reached between different nations aiming at asserting their wills, promoting their interests, in what is in effect perceived by IR realists as an international battle of wills guided primarily by the logic of power. As a purely descriptive claim regarding how nations, for the most part, actually behave, I have no axe to grind with the IR realist, or at least I do not have to grind an axe with them on this matter for the purposes of this paper, but the IR realist is committed to more than merely describing the behaviour of the international order. IR realists, implicitly and paradoxically, are forced, by the logic of their own position, to believe that the ethical ideal that ought to be guiding the international order is the balance of power between competing interests guiding the international behaviour of nations in their quest for power and (alleged) survival. The primary moral dictum of their position is that nations ought to pursue their self-interested interests relentlessly, but only to the extent that the fragile balance of power is not upset (which is, at any rate, a central ingredient for promoting national self-interest). IR realists do not altogether explicitly deny the role of ideals, but the role they assign to ideals is limited and, I will argue, ultimately incoherent, for ideals ought to be understood as flowing from the structure of our embodied existences and into every nook and cranny of our lives, understood individually and collectively, nationally and internationally. We are active creatures, as Aristotle observed, and activities are defined as such in relation to a functional ideal, an ideal of operation, which flows from our specific modes of embodiment. The norms or ends guiding the international political order ought to flow from this understanding of the human subject ideally conceived, as opposed to the largely Machiavellian pessimistic understanding of the human situation informing IR realism; a pessimism that stems from the fallacious move from raw observation to normative recommendation. To claim that our ends are Machiavellian, we shall see, is incoherent and this incoherence is at the heart of IR realism. The demands of reason, we shall see, should push us in the direction of a particular variety of optimism. By using a broadly Aristotelian teleological technique of analysis I will show that IR realists cannot be right. Without placing ideals at the centre of our understandings of our political lives we would be unable properly to understand the political domain, including the specific sphere of concern of IR specialists. The purely observational descriptions alluded to above do not provide the grounds for proper understanding. What does provide a proper understanding, we shall see, is observation through a conceptual lens informed by a teleological understanding of the human person (observation in the light of a conception of the good). That I think a robust conception of the good, of the set of ideals that out to be guiding rational human life, is necessary for properly understanding the international arena does not of course mean that I advocate any such conception of the good. As claimed above, the sort that I advocate, following Aristotle’s footsteps, flows from the specific configuration of our embodied lives. I refer to this form of idealism as realistic idealism.
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Date Issued: 2007

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Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines

- Durmus, Mahmut, Nyokong, Tebello

Authors: Durmus, Mahmut , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/293279 , vital:57071 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
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Date Issued: 2007

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Photophysical, photochemical and bovine serum albumin binding studies on water-soluble gallium (III) phthalocyanine derivatives

- Ogunsipe, Abimbola, Nyokong, Tebello, Durmus, Mahmut

Authors: Ogunsipe, Abimbola , Nyokong, Tebello , Durmus, Mahmut
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/271239 , vital:54524 , xlink:href="https://doi.org/10.1142/S1088424607000746"
Description: Spectral, photophysical, photochemical and bovine serum albumin binding studies on some gallium(III) derivatives - {1,(4)-(tetrapyridyloxyphthalocyaninato)gallium(III), (αGaPc); 2,(3)-(tetrapyridyloxyphthalocyaninato)gallium(III), (βGaPc); and their quaternized derivatives: QαGaPc and QβGaPc)} are hereby presented. β-Substituted complexes are more fluorescent, but show lower tendencies to undergo intersystem crossing than the α-substituted, as judged by their fluorescence and triplet quantum yield values. The quaternized derivatives (QGaPc) are water-soluble and non-aggregated, which makes them potential photosensitizers of choice for photodynamic therapy applications; these amphiphilic compounds also bind strongly to bovine serum albumin in 1:1 stoichiometries, and with binding constants (Kb) in the order of 106 M−1.
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Date Issued: 2007

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Thiol oxidation at 2-mercaptopyrimidine-appended cobalt phthalocyanine modified glassy carbon electrodes

- Obirai, Joseph C, Nyokong, Tebello

Authors: Obirai, Joseph C , Nyokong, Tebello
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/281403 , vital:55722 , xlink:href="https://doi.org/10.1016/j.jelechem.2006.10.033"
Description: The electrocatalytic activity of cobalt tetra-2-mercaptopyrimidylphthalocyanine-modified glassy carbon electrode (CoTMPyrPc-GCE) toward gluthathione, L-cysteine and 2-mercaptoethanol has been investigated. CoTMPyrPc-GCE provides a significant improvement on the reported oxidation potential of L-cysteine in pH 4.0 phosphate buffered solution. The oxidation peak potential (Ep), for L-cysteine, was 0.15 V – a relatively lowered oxidation potential compared to reported phthalocyanine complexes. The electrode prepared by drop-dry/thermal annealing method was very stable and sensitive over a long period of time. The stability has been attributed to the thermal annealing and the structure of the mercaptopyrimidine on the periphery of the CoPc.
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Date Issued: 2007

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