PhDs by publications
- Authors: Niven, Penelope , Grant, Carolyn
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281108 , vital:55693 , xlink:href="https://doi.org/10.1080/13562517.2012.640086"
- Description: PhDs by publications are a relatively new model for doctoral research, especially in the context of the Humanities or Education. This paper describes two writers’ experiences of conducting doctoral studies in this genre and in these faculties. Each discover alternative ways of employing a body of published research papers in development of an overarching thesis. The writers argue that whilst it can be a pragmatic choice for some, PhDs by publications are more likely to be highly complex meta-narratives and that an overview of past research is fraught with theoretical, conceptual and epistemological challenges in the quest for coherence. They claim that the nomenclature ‘PhDs by publications’ or ‘through publications’ is misleading: in the epistemological space of Humanities or Education studies, this mode of doctoral research is more accurately represented as a ‘PhD with or alongside publications’. They conclude that the particular affordance of the model is that it privileges accounts of the process of knowledge building and of descriptions of the gradual emergence of ‘doctoralness’ in the person of the researcher.
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- Date Issued: 2012
Photooxidation of 4-chlorophenol sensitized by lutetium tetraphenoxy phthalocyanine anchored on electrospun polystyrene polymer fiber
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
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- Date Issued: 2012
Photophysical and photochemical properties of novel phthalocyanines bearing non-peripherally substituted mercaptoquinoline moiety
- Authors: Yaşa, Göknur , Erdoğmuş, Ali , Uğur, Ahmet Lütf , Şener, M Kasım , Avcıata, Ulvi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244360 , vital:51250 , xlink:href="https://doi.org/10.1142/S1088424612500940"
- Description: The synthesis, photophysical and photochemical properties of nonperipherally (a) mercaptoquinoline substituted Zn(II), TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, 1 H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.
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- Date Issued: 2012
Photophysical and photochemical studies of sulfur containing phthalocyanine derivatives in the presence of folic acid
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
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- Date Issued: 2012
Photophysics and photochemistry of octaglucosylated zinc phthalocyanine derivatives
- Authors: Iqbal, Zafar , Ogunsipe, Abimbola , Nyokong, Tebello , Lyubimtsev, Alexey , Hanack, Michael , Ziegler, Thomas
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244416 , vital:51255 , xlink:href="https://doi.org/10.1142/S1088424612500630"
- Description: The ground state electronic absorption spectra, photophysics and photochemistry of amphiphilic octaglucosylated zinc phthalocyanines containing oxygen or sulfur bridges are presented. Triplet quantum yield values for the two dyes (in DMF and DMSO) vary between 0.71 and 0.84, while singlet quantum yield values lie between 0.63 and 0.75. Fluorescence lifetimes were determined experimentally by time correlated single photon counting and semi-empirically by fluorescence quenching techniques; and values from both methods were within the same range. Kinetic data were obtained for the quenching of the triplet state of the phthalocyanines by ground state molecular oxygen; the bimolecular collisional quenching rate constant range between 2.35 × 108 and 1.13 × 109 M-1.s-1. These values suggest that triplet states of the dyes are effectively quenched by ground molecular oxygen.
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- Date Issued: 2012
Physico-chemical properties of lutetium phthalocyanine complexes in solution and in solid polystyrene polymer fibers and their application in photoconversion of 4-nitrophenol
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243520 , vital:51160 , xlink:href="https://doi.org/10.1016/j.molcata.2012.02.010"
- Description: The photophysical and photochemical behavior of two phthalocyanine complexes of lutetium peripherally substituted with tetraphenoxy and tetra-2-pyridiloxy groups were studied in solution and when dispersed in polystyrene polymer fiber. The phthalocyanines were found not to fluoresce significantly in solution and not at all within the fiber matrix as compared with standard unsubstituted zinc phthalocyanine. They showed very promising photoactivity in solution with high singlet oxygen quantum yields. Their photoactivity within the polymer fiber matrix was also demonstrated with the photoconversion of 4-nitrophenol, a water pollutant. The photodegradation process with both phthalocyanines follows first order kinetics similar to that observed for the zinc phthalocyanine and the photo-products were found to be hydroquinone, benzoquinone and 4-nitrocatechol.
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- Date Issued: 2012
Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa
- Authors: Rivers-Moore, Nick A , Mantel, Sukhmani K , Dallas, Helen F
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438180 , vital:73441 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2651.pdf
- Description: Key aspects of a river’s temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal met-rics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water tem-perature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readi-lymapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa.
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- Date Issued: 2012
Regular moult-breeding overlap in the Pale-winged Starling Onychognathus nabouroup
- Authors: Craig, Adrian J F K
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449518 , vital:74827 , https://www.tandfonline.com/doi/pdf/10.2989/00306525.2012.737149
- Description: In an earlier publication, with a sample consisting entirely of dated museum specimens, I concluded that, at the population level, moult-breeding overlap occurred in the Pale-winged Starling Onychognathus nabouroup, and in two other southern African Sturnidae, for which both museum skins and ringing records were available (Craig 1983). Subsequently, additional Pale-winged Starling specimens were examined in a reassessment of the subspecies that had been described, but no further analysis of the moult was undertaken (Craig 1988a). As part of a current behavioural study of this species, 58 Pale-winged Starlings were captured and colour-ringed at Augrabies Falls National Park during October 2011, and moult data were recorded for each bird following the standard scoring system for primary wing-feathers (de Beer et al. 2001). This prompted a re-examination of my earlier data, including the application of the Underhill-Zucchini model (Underhill and Zucchini 1988) to the available material.
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- Date Issued: 2012
Remote fingerprinting and multisensor data fusion
- Authors: Hunter, Samuel O , Stalmans, Etienne , Irwin, Barry V W , Richter, John
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429813 , vital:72641 , 10.1109/ISSA.2012.6320449
- Description: Network fingerprinting is the technique by which a device or service is enumerated in order to determine the hardware, software or application characteristics of a targeted attribute. Although fingerprinting can be achieved by a variety of means, the most common technique is the extraction of characteristics from an entity and the correlation thereof against known signatures for verification. In this paper we identify multiple host-defining metrics and propose a process of unique host tracking through the use of two novel fingerprinting techniques. We then illustrate the application of host fingerprinting and tracking for increasing situational awareness of potentially malicious hosts. In order to achieve this we provide an outline of an adapted multisensor data fusion model with the goal of increasing situational awareness through observation of unsolicited network traffic.
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- Date Issued: 2012
Representations of the subject ‘woman’ and the politics of abortion: an analysis of South African newspaper articles from 1978 to 2005
- Authors: Macleod, Catriona I , Feltham-King, Tracey
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446286 , vital:74487 , xlink:href="https://doi.org/10.1080/13691058.2012.685760"
- Description: A key element in cultural and gender power relations surrounding abortion is how women who undergo an abortion are represented in public talk. We analyse how women were named and positioned, and the attendant constructions of abortion, in South African newspaper articles on abortion from 1978 to 2005, a period during which there were radical political and legislative shifts. The name ‘woman’ was the most frequently used (70% of articles) followed by ‘girl/teenager/child’ (25%), ‘mother’ (25%), ‘patient’ (11%) and ‘minor’ (6%). The subject positionings enabled by these names were dynamic and complex and were interwoven with the localised, historical politics of abortion. The ‘innocent mother’ and the bifurcated ‘patient’ (woman/foetus) positionings were invoked in earlier epochs to promote abortion under medical conditions. The ‘dangerous mother’ and woman as ‘patient’ positionings were used more frequently under liberal abortion legislation to oppose and to advocate for abortion, respectively. The positioning of the ‘girl/teenager/child’ as dependent and vulnerable was used in contradictory ways, both to oppose abortion and to argue for a liberalisation of restrictive legislation, depending on the attendant construction of abortion. The neutral naming of ‘woman’ was, at times, linked to the liberal imaginary of ‘choice’.
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- Date Issued: 2012
Reverse saturation absorption spectra and optical limiting properties of chlorinated tetrasubstituted phthalocyanines containing different metals
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
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- Date Issued: 2012
Schottky barrier diode parameters of Ag/MgPc/p-Si structure
- Authors: Canlıca, Mevlüde , Coskun, Mustafa , Altındal, Ahmet , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245820 , vital:51408 , xlink:href="https://doi.org/10.1142/S1088424612500824"
- Description: An Ag/Pc/p-Si Schottky barrier (SB) diode was fabricated. The current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G-V) measurements were carried out to determine the characteristic parameters such as barrier height, ideality factor and series resistance of the SB diode. The non-linear behavior of ln (I) vs. ln (V) and ln (I/V) vs. V1/2 plots indicated that the thermoionic emission theory can be applied to evaluate junction parameters for the investigated SB diode rather than space-charge limited conduction (SCLC) mechanism and bulk-limited Poole–Frenkel emission. The bulk doping concentration NB and fixed oxide charges Nf was determined from the measured high frequency C-V curve and was found to be 9.5 × 1014 cm-3 and 2.3 × 1013 cm-2, respectively. The values of barrier height obtained from Norde's function were compared with those from the forward bias current-voltage characteristic, and it was seen that there was a good agreement between barrier heights from both methods.
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- Date Issued: 2012
Seasonal distribution, breeding season and wing moult in the Splendid Glossy Starling Lamprotornis splendidus
- Authors: Craig, Adrian J F K
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449535 , vital:74828 , https://doi.org/10.2989/00306525.2012.655429
- Description: Seasonal migration by Splendid Glossy Starlings has been confirmed only for Kenya and Zambia. Populations in almost all other countries have been categorised as ‘resident’ by some observers, but ‘nomadic’ is a more accurate description of their status. The breeding season is accurately known for few localities. Estimates for the duration of wing moult ranged from 70–130 d based on small samples. Regional divergences in the timing of wing moult remain open to three possible interpretations: (1) differences between years in the timing of wing moult; (2) differences between sex and/or age classes; and (3) population movements, so that birds from different regions may successively occupy the same areas. The available data are inadequate to resolve these questions.
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- Date Issued: 2012
Single walled carbon nanotubes functionalized with nickel phthalocyanines
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245843 , vital:51410 , xlink:href="https://doi.org/10.1142/S1088424611004439"
- Description: In this work we report on electrochemical behavior of nickel phthalocyanine derivatives tetrasubstituted peripherally and non-peripherally with hydroxy and used to modify single walled carbon nanotubes. Nickel phthalocyanine complex octasubstituted at the peripheral positions with hydroxy groups was also used to modify single walled carbon nanotubes. Nickel phthalocyanine complex tetrasubstituted with amino groups at peripheral position was covalently and non-covalently linked to single walled carbon nanotubes. All the conjugates of nickel phthalocyanine derivatives with single walled carbon nanotubes were used for the electro oxidation of 4-chlorophenol. The nickel phthalocyanine octabsubstituted with hydroxy groups at the non-peripheral positions gave the best current response and the best resistance against electrode fouling for the oxidation of 4-chlorophenol.
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- Date Issued: 2012
Spectral, photophysical and photochemical properties of tetra-and octaglycosylated zinc phthalocyanines
- Authors: Iqbal, Zafar , Masilela, Nkosiphile , Nyokong, Tebello , Lyubimtsev, Alexey , Hanack, Michael , Ziegler, Thomas
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244428 , vital:51256 , xlink:href="https://doi.org/10.1039/c2pp05348a"
- Description: Photophysical and photochemical properties of a series of tetra- and octaglycosylated zinc phthalocyanines (ZnPcs) substituted with glucose and galactose moieties have been reported. Spectral properties of these phthalocyanines are compared in DMSO. Absorption spectra of the non-peripherally tetra-substituted ZnPcs 2 showed a significant red shift in their Q-band maxima as compared to the peripherally substituted analog 1. All the complexes gave high triplet quantum yields ranging from 0.68 to 0.88, whereas triplet lifetimes were in the range of 100–430 µs in argon-saturated solutions. The octagalactosylated ZnPc 3b showed the highest triplet quantum yield and singlet oxygen quantum yield of 0.88 and 0.69, respectively. The fluorescence quantum yields and lifetimes of all the compounds under investigation were within the range of zinc phthalocyanine complexes.
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- Date Issued: 2012
Spectroscopic and physicochemical behavior of magnesium phthalocyanine derivatives mono-substituted with a carboxylic acid group
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244450 , vital:51258 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.12.051"
- Description: This work reports on the synthesis of novel unsymmetrically substituted magnesium phthalocyanine complexes containing one carboxyl group. The physicochemical behavior of these complexes were compared with those of their unmetallated and zinc counterparts. The MgPcs showed interesting absorption spectra with [8,15,22-Tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyaninato]magnesium (II) showing a large split in the Q band whereas [8,15,22-Tris-(naphtho)-2-(carboxy) phthalocyaninato]magnesium(II) presented only a small splitting. The magnesium phthalocyanine derivatives displayed higher fluorescence quantum yields compared to unmetallated and zinc phthalocyanine counterparts. The latter gave admirable triplet and singlet oxygen quantum yields. These molecules can distinctly be employed in the field of photodynamic therapy in combination with fluorescence imaging.
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- Date Issued: 2012
Students’ navigation of the uncharted territories of academic writing
- Authors: Bharuthram, Sharita , McKenna, Sioux
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187373 , vital:44626 , xlink:href="https://doi.org/10.1080/18146627.2012.742651"
- Description: Many students enter tertiary education unfamiliar with the ‘norms and conventions’ of their disciplines. Research into academic literacies has shown that in order to succeed in their studies, students are expected to conform to these norms and conventions, which are often unrecognized or seen as ‘common sense’ by lecturers. Students have to develop their own ‘map’ of their programme’s expectations in order to make sense of the seemingly mysterious practices they are expected to take on. This study, undertaken at a University of Technology in South Africa, details students’ perceptions of their writing difficulties and their attempts to navigate their way through various writing tasks. The findings reveal that students experience a range of difficulties and that the students often feel unsupported in their travails with academic writing.
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- Date Issued: 2012
Syntheses, protonation constants and antimicrobial activity of 2-substituted N-alkylimidazole derivatives
- Authors: Kleyi, Phumelele , Walmsley, Ryan S , Gundhla, Isaac Z , Walmsley, Tara A , Jauka, Tembisa I , Dames, Joanna F , Walker, Roderick B , Torto, Nelson , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184066 , vital:44165 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/123858"
- Description: A series of N-alkylimidazole-2-carboxylic acid, N-alkylimidazole-2-carboxaldehyde and N-alkylimidazole-2-methanol derivatives [alkyl = benzyl, methyl, ethyl, propyl, butyl, heptyl, octyl and decyl] have been synthesized and the protonation constants determined. The antimicrobial properties of the compounds were tested against Gram-negative (Escherichi coli), Gram-positive (Staphylococcus aureus and Bacillus subtilis subsp. spizizenii) bacterial strains and yeast (C. albicans). Both the disk diffusion and broth microdilution methods for testing the antimicrobial activity showed that N-alkylation of imidazole with longer alkyl chains and the substitution with low pKa group at 2-position resulted in enhanced antimicrobial activity. Particularly, the N-alkylimidazole-2-carboxylic acids exhibited the best antimicrobial activity due to the low pKa of the carboxylic acid moiety. Generally, all the N-alkylimidazole derivatives were most active against the Gram-positive bacteria [S. aureus (MIC = 5–160 µg mL–1) and B. subtilis subsp. spizizenii (5–20 µg mL–1)], with the latter more susceptible. All the compounds showed poor antimicrobial activity against both Gram-negative (E. coli, MIC = 0.15 to >2500 µg mL–1) bacteria and all the compounds were inactive against the yeast (Candida albicans).
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- Date Issued: 2012
Synthesis and photophysical behavior of a novel zinc phthalocyanine containing a single carboxylic acid and three phenylthio substituents
- Authors: Forteath, Shaun , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243207 , vital:51127 , xlink:href="https://doi.org/10.1016/j.jlumin.2012.03.050"
- Description: Zinc 2, (3)-tri-(phenylthio)-2, (3)-carboxy phthalocyanine (ZnPc(COOH)(SPh)3), zinc 2, (3)-tetra-(phenylthio) phthalocyanine (ZnPc(SPh)4) and 2, (3)-tetra-(phenylthio) phthalocyanine (H2Pc(SPh)4) were synthesized and their photophysical behavior were compared with those of a number of zinc phthalocyanine (ZnPc) derivatives. ZnPc(COOH)(SPh)3 and ZnPc(SPh)4 had similar fluorescence (ΦF=0.14) and triplet state (ΦT=0.65) quantum yields in dimethylsulfoxide, hence showing no effects of the replacement of one of the phenylthio groups with a carboxylic acid group. ZnPc(COOH)(SPh)3 displayed a slightly shorter triplet lifetime (τT=331 μs) than ZnPc (τT=350 μs) in DMSO, but within the range of ZnPc derivatives. The triplet lifetime for ZnPc(COOH)(SPh)3 is much longer than for the symmetrical derivative (ZnPc(SPh)4) with τT=149 μs in DMSO.
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- Date Issued: 2012
Synthesis and photophysical properties of covalent conjugates of aqua platinum (II) and octacarboxy-substituted zinc phthalocyanine
- Authors: Bulgakov, Roman A , Kuznetsova, Nina A , Dolotova, Olga V , Solovieva, Ludmila I , Mack, John , Chidawanyika, Wadzanai J U , Kaliya, Oleg L , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242726 , vital:51073 , xlink:href="https://doi.org/10.1142/S1088424612501209"
- Description: New covalent conjugates of aqua platinum(II) and octacarboxy-substituted zinc phthalocyanine, bearing one, two, three and four aqua platinum moieties on the periphery of the Pc ligand have been synthesized and characterized. The effect of the stepwise introduction of the aqua platinums on the photophysical and photochemical properties of these compounds has been investigated in dimethylsulfoxide solution. It has been found that aqua platinum moieties have only a limited effect on the dynamics of the singlet and triplet excited states, on the ability to sensitize singlet oxygen formation and on the photostability. Each conjugate has a high singlet oxygen quantum yield (ΦΔ 0.51–0.62) and thus retains potential for use as a dual action anticancer drugs by acting as a sensitizer for PDT in addition to the likely chemotherapeutic effects of the Pt(II) complexes.
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- Date Issued: 2012