Swazi oral literature, eco-culture and environmental apocalypse
- Authors: Enongene Mirabeau Sone
- Date: 2016
- Subjects: Swazi oral literature; eco-culture; eco-literature; eco-criticism; environmental sustainability
- Language: English
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/2632 , vital:42302
- Description: The main objective of this paper is to show how oral literature is engaged by Swazis with regards to environmental sustainability. It demonstrates the relationship between nature and culture as reflected in Swazi oral literature and how indigenous knowledge embedded in this literature can be used to expand the concepts of eco-literature and eco-criticism. The paper argues that the indigenous environmental expertise among the Swazi people, encapsulated in their oral literature, can serve as a critical resource base for the process of developing a healthy environment. Furthermore, the paper contends that eco-criticism, which is essentially a Western concept, can benefit by drawing inspiration from the indigenous knowledge contained in Swazi culture and expressed in their oral literature. The paper concludes by recommending the need to strengthen traditional and customary knowledge and practices by protecting and recognizing the values of such systems in the conservation of biodiversity for sustainable development
- Full Text:
- Authors: Enongene Mirabeau Sone
- Date: 2016
- Subjects: Swazi oral literature; eco-culture; eco-literature; eco-criticism; environmental sustainability
- Language: English
- Type: Journal Article
- Identifier: http://hdl.handle.net/11260/2632 , vital:42302
- Description: The main objective of this paper is to show how oral literature is engaged by Swazis with regards to environmental sustainability. It demonstrates the relationship between nature and culture as reflected in Swazi oral literature and how indigenous knowledge embedded in this literature can be used to expand the concepts of eco-literature and eco-criticism. The paper argues that the indigenous environmental expertise among the Swazi people, encapsulated in their oral literature, can serve as a critical resource base for the process of developing a healthy environment. Furthermore, the paper contends that eco-criticism, which is essentially a Western concept, can benefit by drawing inspiration from the indigenous knowledge contained in Swazi culture and expressed in their oral literature. The paper concludes by recommending the need to strengthen traditional and customary knowledge and practices by protecting and recognizing the values of such systems in the conservation of biodiversity for sustainable development
- Full Text:
Synthesis and biological evaluation of novel thiazole-based compounds
- Authors: Olawode, Emmanual Oladayo
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62955 , vital:28325
- Description: Thesis embargoed for one-year period. Expected date of release: April 2019
- Full Text:
- Date Issued: 2016
- Authors: Olawode, Emmanual Oladayo
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62955 , vital:28325
- Description: Thesis embargoed for one-year period. Expected date of release: April 2019
- Full Text:
- Date Issued: 2016
Synthesis and characterisation of lanthanide complexes with nitrogen- and oxygen-donor ligands
- Authors: Madanhire, Tatenda
- Date: 2016
- Subjects: Rare earth metals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13127 , vital:27154
- Description: The reactions of Ln(NO3)3∙6H2O (Ln = Pr, Nd or Er) with the potentially tridentate O,N,O chelating ligand 2,6-pyridinedimethanol (H2pydm) were investigated, and complexes with the formula, [Ln(H2pydm)2(NO3)2](NO3) (Ln = Pr or Nd) and [Er(H2pydm)3](NO3)3 were isolated. The ten-coordinate Pr(III) and Nd(III) compounds crystallise in the triclinic space group P-1 while the nine-coordinate Er(III) complex crystallises in the monoclinic system (P21/n). The reaction of PrCl3∙6H2O with H2pydm yielded the compound, [Pr(H2pydm)3](Cl)3, that crystallises in the monoclinic system, space group P21/c with α = 90, β = 98.680(1) and γ = 90°. The nine-coordinate Pr(III) ion is bound to three H2pydm ligands, with bond distances Pr-O 2.455(2)-2.478(2) Å and Pr-N 2.6355(19)-2.64(2) Å. X-ray crystal structures of all the H2pydm complexes reveal that the ligand coordinates tridentately, via the pyridyl nitrogen atom and the two hydroxyl oxygen atoms. The electronic absorption spectra of complexes show 4f-4f transitions. Rare-earth complexes, [Ln(H2L1)2(NO3)3] [Ln = Gd, Ho or Nd], were also prepared from a Schiff base. The X-ray single-crystal diffraction studies and SHAPE analyses of the Gd(III) and Ho(III) complexes shows that the complexes are ten-coordinate and exhibit distorted tetradecahedron geometries. With proton migration occurring from the phenol group to the imine function, complexation of the lanthanides to the ligand gives the ligand a zwitterionic phenoxo-iminium form. A phenolate oxygen-bridged dinuclear complex, [Ce2(H2L1)(ovan)3(NO3)3], has been obtained by reacting Ce(NO3)3∙6H2O with an o-vanillin derived Schiff base ligand, 2-((E)-(1-hydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol (H2L1). Hydrolysis of the Schiff base occurred to yield o-vanillin, which bridged two cerium atoms with the Ce∙∙∙Ce distance equal to 3.823 Å. The Ce(III) ions are both tencoordinate, but have different coordination environments, showing tetradecahedron and staggered dodecahedron geometries, respectively. The reaction of salicylaldehyde-N(4)-diethylthiosemicarbazone (H2L2) in the presence of hydrated Ln(III) nitrates led to the isolation of two novel compounds: (E)-2[(ortho-hydroxy)benzylidene]-2-(thiomethyl)-thionohydrazide (1) and bis[2,3-diaza4-(2-hydroxyphenyl)-1-thiomethyl-buta-1,3-diene]disulfide. The latter is a dimer of the former. For this asymmetric Schiff base, 1 and the symmetric disulfide, classical hydrogen bonds of the O–H∙∙∙N as well as N–H∙∙∙S (for 1) type are apparent next to C–H∙∙∙O contacts. 4-(4-Bromophenyl)-1-(propan-2-ylidene)thiosemicarbazide was also prepared upon reacting 4-(4-bromophenyl)-3-thiosemicarbazide with acetone in the presence of ethanol and La(NO3)3∙6H2O. The C=S bond length was found to be 1.6686(16) Å which is in good agreement with other thioketones whose metrical parameters have been deposited with the Cambridge Structural Database. Classical hydrogen bonds of the N–H∙∙∙N and the N–H∙∙∙Br type are observed next to C–H∙∙∙S contacts. All synthesised compounds were characterised by microanalyses, single-crystal X-ray diffraction (except for [Nd(H2L1)2(NO3)3]), 1H NMR and IR spectroscopy.
- Full Text:
- Date Issued: 2016
- Authors: Madanhire, Tatenda
- Date: 2016
- Subjects: Rare earth metals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13127 , vital:27154
- Description: The reactions of Ln(NO3)3∙6H2O (Ln = Pr, Nd or Er) with the potentially tridentate O,N,O chelating ligand 2,6-pyridinedimethanol (H2pydm) were investigated, and complexes with the formula, [Ln(H2pydm)2(NO3)2](NO3) (Ln = Pr or Nd) and [Er(H2pydm)3](NO3)3 were isolated. The ten-coordinate Pr(III) and Nd(III) compounds crystallise in the triclinic space group P-1 while the nine-coordinate Er(III) complex crystallises in the monoclinic system (P21/n). The reaction of PrCl3∙6H2O with H2pydm yielded the compound, [Pr(H2pydm)3](Cl)3, that crystallises in the monoclinic system, space group P21/c with α = 90, β = 98.680(1) and γ = 90°. The nine-coordinate Pr(III) ion is bound to three H2pydm ligands, with bond distances Pr-O 2.455(2)-2.478(2) Å and Pr-N 2.6355(19)-2.64(2) Å. X-ray crystal structures of all the H2pydm complexes reveal that the ligand coordinates tridentately, via the pyridyl nitrogen atom and the two hydroxyl oxygen atoms. The electronic absorption spectra of complexes show 4f-4f transitions. Rare-earth complexes, [Ln(H2L1)2(NO3)3] [Ln = Gd, Ho or Nd], were also prepared from a Schiff base. The X-ray single-crystal diffraction studies and SHAPE analyses of the Gd(III) and Ho(III) complexes shows that the complexes are ten-coordinate and exhibit distorted tetradecahedron geometries. With proton migration occurring from the phenol group to the imine function, complexation of the lanthanides to the ligand gives the ligand a zwitterionic phenoxo-iminium form. A phenolate oxygen-bridged dinuclear complex, [Ce2(H2L1)(ovan)3(NO3)3], has been obtained by reacting Ce(NO3)3∙6H2O with an o-vanillin derived Schiff base ligand, 2-((E)-(1-hydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol (H2L1). Hydrolysis of the Schiff base occurred to yield o-vanillin, which bridged two cerium atoms with the Ce∙∙∙Ce distance equal to 3.823 Å. The Ce(III) ions are both tencoordinate, but have different coordination environments, showing tetradecahedron and staggered dodecahedron geometries, respectively. The reaction of salicylaldehyde-N(4)-diethylthiosemicarbazone (H2L2) in the presence of hydrated Ln(III) nitrates led to the isolation of two novel compounds: (E)-2[(ortho-hydroxy)benzylidene]-2-(thiomethyl)-thionohydrazide (1) and bis[2,3-diaza4-(2-hydroxyphenyl)-1-thiomethyl-buta-1,3-diene]disulfide. The latter is a dimer of the former. For this asymmetric Schiff base, 1 and the symmetric disulfide, classical hydrogen bonds of the O–H∙∙∙N as well as N–H∙∙∙S (for 1) type are apparent next to C–H∙∙∙O contacts. 4-(4-Bromophenyl)-1-(propan-2-ylidene)thiosemicarbazide was also prepared upon reacting 4-(4-bromophenyl)-3-thiosemicarbazide with acetone in the presence of ethanol and La(NO3)3∙6H2O. The C=S bond length was found to be 1.6686(16) Å which is in good agreement with other thioketones whose metrical parameters have been deposited with the Cambridge Structural Database. Classical hydrogen bonds of the N–H∙∙∙N and the N–H∙∙∙Br type are observed next to C–H∙∙∙S contacts. All synthesised compounds were characterised by microanalyses, single-crystal X-ray diffraction (except for [Nd(H2L1)2(NO3)3]), 1H NMR and IR spectroscopy.
- Full Text:
- Date Issued: 2016
Synthesis and characterization of group 12 dithiolate complexes as single source precursors for the preparation of hexadecylamine capped metal sulfide nanoparticles and polymer
- Authors: Osuntokun, Jejenija
- Date: 2016
- Subjects: Nanotechnology Nanoparticles Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/14060 , vital:39801
- Description: A series of heteroleptic mixed ligand complexes of some alkyl substituted thiourea, tetramethyl thiuram disulfide and 1-cyano-1-carboethoxy-2,2 ditholate of Zn(II) Cd(II) and Hg(II) have been synthesized by stoichiometry reactions of the ligands with respective metal salts. They have been characterized with analytical and spectroscopic techniques. Seven out of the 19 complexes synthesized are pyridine 2, 2 bipyridine and 1, 10 phenanthroline adducts of dissopropyl parent adducts of Zn(II) and Cd(II) complexes. All the complexes are proposed as four coordinate except the pyridine adducts, 2, 2’ bipyridine and 1, 10 phenanhroline adducts that are proposed as five and six coordinate respectively. All the complexes are solid, air stable and moisture stable for a many months. They are not soluble in common organic solvents but partially soluble in coordinating solvents like DMF and DMSO and due to their insolubility problems all attempts to grow single crystal of the complexes proved abortive. The complexes gave respective metal sulfide on thermal decomposition in TGA and this makes them to be potentially useful single source precursor for the synthesis of metal sulfide. All the complexes were invariably thermolysed in HDA to synthesis a series of HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles reveal that they are all blue-shifted from the absorbance edge and this confirms quantum confinement of the nanoparticles. The transmittance electron microscope showed that the nanoparticles are in nanodimension. ZnS nanoparticles from the pyridine adducts gave HDA-capped ZnS nanoparticles with a mixture of hexagonal and cubic phases while the HDA capped CdS from the 2, 2 bipyridine and 1,10 phenanthroline gave anisotropic nanoparticles. The sizes of the CdS from the 1,10 phenanthroline adducts were also found to be biggest while CdS nanoparticles from 2,2 bipyridine adduct were also revealed to be bigger than the particle sizes obtained from the parent complex, (1-cyano-1 carboethoxyethylene-2,2-dithiolato- κ,S’S)-bis(N, N’-diisopropylthiourea -κS)cadmium(II). ZnS and CdS polymer encapsulated nanocomposites were also synthesized using a solution casting method. The polymers employed were; Polymethyl metharcrylate (PMMA), Poly(vinly alcohol) (PVA), and poly vinyl pyrrolidone (PVP). The structural and thermal properties of the pure polymers and the respective nanocomposites were investigated. It was observed that the ZnS/PVA and CdS/PVA were the most thermally stable composites when the thermal stability of the pure polymers were compared relative to the nanocomposites using data obtained from thermal decomposition results of the TGA.
- Full Text:
- Date Issued: 2016
- Authors: Osuntokun, Jejenija
- Date: 2016
- Subjects: Nanotechnology Nanoparticles Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/14060 , vital:39801
- Description: A series of heteroleptic mixed ligand complexes of some alkyl substituted thiourea, tetramethyl thiuram disulfide and 1-cyano-1-carboethoxy-2,2 ditholate of Zn(II) Cd(II) and Hg(II) have been synthesized by stoichiometry reactions of the ligands with respective metal salts. They have been characterized with analytical and spectroscopic techniques. Seven out of the 19 complexes synthesized are pyridine 2, 2 bipyridine and 1, 10 phenanthroline adducts of dissopropyl parent adducts of Zn(II) and Cd(II) complexes. All the complexes are proposed as four coordinate except the pyridine adducts, 2, 2’ bipyridine and 1, 10 phenanhroline adducts that are proposed as five and six coordinate respectively. All the complexes are solid, air stable and moisture stable for a many months. They are not soluble in common organic solvents but partially soluble in coordinating solvents like DMF and DMSO and due to their insolubility problems all attempts to grow single crystal of the complexes proved abortive. The complexes gave respective metal sulfide on thermal decomposition in TGA and this makes them to be potentially useful single source precursor for the synthesis of metal sulfide. All the complexes were invariably thermolysed in HDA to synthesis a series of HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles reveal that they are all blue-shifted from the absorbance edge and this confirms quantum confinement of the nanoparticles. The transmittance electron microscope showed that the nanoparticles are in nanodimension. ZnS nanoparticles from the pyridine adducts gave HDA-capped ZnS nanoparticles with a mixture of hexagonal and cubic phases while the HDA capped CdS from the 2, 2 bipyridine and 1,10 phenanthroline gave anisotropic nanoparticles. The sizes of the CdS from the 1,10 phenanthroline adducts were also found to be biggest while CdS nanoparticles from 2,2 bipyridine adduct were also revealed to be bigger than the particle sizes obtained from the parent complex, (1-cyano-1 carboethoxyethylene-2,2-dithiolato- κ,S’S)-bis(N, N’-diisopropylthiourea -κS)cadmium(II). ZnS and CdS polymer encapsulated nanocomposites were also synthesized using a solution casting method. The polymers employed were; Polymethyl metharcrylate (PMMA), Poly(vinly alcohol) (PVA), and poly vinyl pyrrolidone (PVP). The structural and thermal properties of the pure polymers and the respective nanocomposites were investigated. It was observed that the ZnS/PVA and CdS/PVA were the most thermally stable composites when the thermal stability of the pure polymers were compared relative to the nanocomposites using data obtained from thermal decomposition results of the TGA.
- Full Text:
- Date Issued: 2016
Synthesis and dark toxicity of 5-(4-carboxyphenyl)-10, 15, 20-tris (phenyl)-porphyrinato chlorido gallium (III) when conjugated to δ-aminolevulinic acid
- Managa, Muthumuni, Mkhize, Scebi, Britton, Jonathan, Prinsloo, Earl, Nyokong, Tebello
- Authors: Managa, Muthumuni , Mkhize, Scebi , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240014 , vital:50789 , xlink:href="https://doi.org/10.1080/00958972.2016.1223292"
- Description: 5-(4-Carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato chlorido gallium(III) (2) was synthesized and then linked to ethyl ester δ-aminolevulinic acid to form 3. There was no shift in Soret band following conjugation. The fluorescence and singlet oxygen generating behavior of the porphyrins were also investigated. The highest singlet oxygen quantum yield (ΦΔ) obtained was that of 3. Complexes 2 and 3 as well as metal free 5-(4-carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato showed no dark toxicity on MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2016
- Authors: Managa, Muthumuni , Mkhize, Scebi , Britton, Jonathan , Prinsloo, Earl , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240014 , vital:50789 , xlink:href="https://doi.org/10.1080/00958972.2016.1223292"
- Description: 5-(4-Carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato chlorido gallium(III) (2) was synthesized and then linked to ethyl ester δ-aminolevulinic acid to form 3. There was no shift in Soret band following conjugation. The fluorescence and singlet oxygen generating behavior of the porphyrins were also investigated. The highest singlet oxygen quantum yield (ΦΔ) obtained was that of 3. Complexes 2 and 3 as well as metal free 5-(4-carboxyphenyl)-10,15,20-tris(phenyl)-porphyrinato showed no dark toxicity on MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2016
Synthesis and evaluation of substituted 4-(N-benzylamino)cinnamate esters as potential anti-cancer agents and HIV-1 integrase inhibitors
- Faridoon, H, Edkins, Adrienne L, Isaacs, Michelle, Mnkandhla, Dumisani, Hoppe, Heinrich C, Kaye, Perry T
- Authors: Faridoon, H , Edkins, Adrienne L , Isaacs, Michelle , Mnkandhla, Dumisani , Hoppe, Heinrich C , Kaye, Perry T
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66289 , vital:28929 , https://doi.org/10.1016/j.bmcl.2016.05.023
- Description: publisher version , Encouraging selectivity and low micromolar activity against HeLa cervical carcinoma (IC50 ⩾ 3.0 μM) and the aggressive MDA-MB-231 triple negative breast carcinoma (IC50 ⩾ 9.6 μM) cell lines has been exhibited by a number of readily accessible 4-(N-benzylamino)cinnamate esters. The potential of the ligands as HIV-1 integrase inhibitors has also been examined.
- Full Text: false
- Date Issued: 2016
- Authors: Faridoon, H , Edkins, Adrienne L , Isaacs, Michelle , Mnkandhla, Dumisani , Hoppe, Heinrich C , Kaye, Perry T
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66289 , vital:28929 , https://doi.org/10.1016/j.bmcl.2016.05.023
- Description: publisher version , Encouraging selectivity and low micromolar activity against HeLa cervical carcinoma (IC50 ⩾ 3.0 μM) and the aggressive MDA-MB-231 triple negative breast carcinoma (IC50 ⩾ 9.6 μM) cell lines has been exhibited by a number of readily accessible 4-(N-benzylamino)cinnamate esters. The potential of the ligands as HIV-1 integrase inhibitors has also been examined.
- Full Text: false
- Date Issued: 2016
Synthesis and exploration of resorcinol derivatives as Plasmodium falciparum Hsp90 inhibitors
- Authors: Umumararungu, Théoneste
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/717 , vital:19984
- Description: In this research project, we have synthesized a series of nine dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38, a potent Hsp90 inhibitor. These analogues were chosen because they share the same pharmacophore with NMS-E973 (L-1) 38 and were thus expected to have a similar biological activity. Moreover, it is generally easier to synthesize the dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38 as compared to their demethylated counterparts. Since other Hsp90 inhibitors such as geldanamycin 19 have demonstrated anti-plasmodial activity, we also expected our compounds to be Hsp90 inhibitors and to possess anti-plasmodial activity. However, our compounds were tested for growth inhibitory activity of Plasmodium falciparum and not for P. falciparum Hsp90 (PfHSP90) inhibitory activity. The synthesis involved a series of steps that led to the formation of the ester compound TU-011 (L-7) 43 that was then used as a precursor for different NMS-E973 (L-1) 38 analogues. The choice of analogues to be synthesized was dictated by binding affinity predictions obtained from molecular docking. The chosen synthetic analogues were active against chloroquine-sensitive Plasmodium falciparum (3D7 strain) in a Plasmodium lactate dehydrogenase assay and they were not generally cytotoxic to human cervical adenocarcinoma cell line HeLa. The most active of our compounds was TU-018 (L-103) 50 with an IC50 value of approximately 1.830 µM as compared to the standard, chloroquine, with an IC50 value of 0.01062 µM. Some of the compounds showed mild cytotoxicity towards HeLa cells with IC50 values higher than 25 µM as compared to the standard apoptosis inducer drug, emetine that had an IC50 value of 0.09948 µM. These results highlight the fact that the synthesized analogues are novel relatively non-toxic anti-plasmodial agents.
- Full Text:
- Date Issued: 2016
- Authors: Umumararungu, Théoneste
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/717 , vital:19984
- Description: In this research project, we have synthesized a series of nine dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38, a potent Hsp90 inhibitor. These analogues were chosen because they share the same pharmacophore with NMS-E973 (L-1) 38 and were thus expected to have a similar biological activity. Moreover, it is generally easier to synthesize the dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38 as compared to their demethylated counterparts. Since other Hsp90 inhibitors such as geldanamycin 19 have demonstrated anti-plasmodial activity, we also expected our compounds to be Hsp90 inhibitors and to possess anti-plasmodial activity. However, our compounds were tested for growth inhibitory activity of Plasmodium falciparum and not for P. falciparum Hsp90 (PfHSP90) inhibitory activity. The synthesis involved a series of steps that led to the formation of the ester compound TU-011 (L-7) 43 that was then used as a precursor for different NMS-E973 (L-1) 38 analogues. The choice of analogues to be synthesized was dictated by binding affinity predictions obtained from molecular docking. The chosen synthetic analogues were active against chloroquine-sensitive Plasmodium falciparum (3D7 strain) in a Plasmodium lactate dehydrogenase assay and they were not generally cytotoxic to human cervical adenocarcinoma cell line HeLa. The most active of our compounds was TU-018 (L-103) 50 with an IC50 value of approximately 1.830 µM as compared to the standard, chloroquine, with an IC50 value of 0.01062 µM. Some of the compounds showed mild cytotoxicity towards HeLa cells with IC50 values higher than 25 µM as compared to the standard apoptosis inducer drug, emetine that had an IC50 value of 0.09948 µM. These results highlight the fact that the synthesized analogues are novel relatively non-toxic anti-plasmodial agents.
- Full Text:
- Date Issued: 2016
Synthesis and optical limiting properties of new lanthanide bis-and tris-phthalocyanines
- Sekhosana, Kutloana Edward, Manyeruke, Meloddy Hlatini, Nyokong, Tebello
- Authors: Sekhosana, Kutloana Edward , Manyeruke, Meloddy Hlatini , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240063 , vital:50795 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.05.068"
- Description: This manuscript reports on syntheses of new multi-decker phthalocyanines, namely: bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} cerium(III) (2), tris-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} dicerium(III) (4) and bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} gadolinium(III) (5). Complex 4 which is a tris phthalocyanine showed better nonlinear optical behavior in solution than 2 which is a bis phthalocyanine, both containing the same central metal, Ce. All the three molecules possess good optical limiting properties judged by the limiting threshold values which ranged from 0.04 to 0.09 J cm−2 with complex 5 embedded in thin films, showing the lowest value of 0.04 J cm−2. Furthermore, nonlinear optical processes responsible for reverse saturable absorption data are investigated.
- Full Text:
- Date Issued: 2016
- Authors: Sekhosana, Kutloana Edward , Manyeruke, Meloddy Hlatini , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240063 , vital:50795 , xlink:href="https://doi.org/10.1016/j.molstruc.2016.05.068"
- Description: This manuscript reports on syntheses of new multi-decker phthalocyanines, namely: bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} cerium(III) (2), tris-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} dicerium(III) (4) and bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} gadolinium(III) (5). Complex 4 which is a tris phthalocyanine showed better nonlinear optical behavior in solution than 2 which is a bis phthalocyanine, both containing the same central metal, Ce. All the three molecules possess good optical limiting properties judged by the limiting threshold values which ranged from 0.04 to 0.09 J cm−2 with complex 5 embedded in thin films, showing the lowest value of 0.04 J cm−2. Furthermore, nonlinear optical processes responsible for reverse saturable absorption data are investigated.
- Full Text:
- Date Issued: 2016
Synthesis and photophysicochemical properties of BODIPY dye functionalized gold nanorods for use in antimicrobial photodynamic therapy
- Kubheka, Gugu, Uddin, Imran, Amuhaya, Edith, Mack, John, Nyokong, Tebello
- Authors: Kubheka, Gugu , Uddin, Imran , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239897 , vital:50778 , xlink:href="https://doi.org/10.1142/S108842461650070X"
- Description: A series of boron dipyrromethene (BODIPY) dyes with properties that are ideal for a good photosensitizer have been prepared. Functionalization with bromine atoms and attachment to gold nanoparticles through a meso-aniline group results in high singlet oxygen quantum yields and low fluorescent quantum yields. Molecular modelling was used to analyze trends in the MO energies of various brominated aniline BODIPY dyes.
- Full Text:
- Date Issued: 2016
- Authors: Kubheka, Gugu , Uddin, Imran , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239897 , vital:50778 , xlink:href="https://doi.org/10.1142/S108842461650070X"
- Description: A series of boron dipyrromethene (BODIPY) dyes with properties that are ideal for a good photosensitizer have been prepared. Functionalization with bromine atoms and attachment to gold nanoparticles through a meso-aniline group results in high singlet oxygen quantum yields and low fluorescent quantum yields. Molecular modelling was used to analyze trends in the MO energies of various brominated aniline BODIPY dyes.
- Full Text:
- Date Issued: 2016
Synthesis and physicochemical properties of zinc and indium phthalocyanines conjugated to quantum dots, gold and magnetic nanoparticles
- Osifeko, Olawale, Nyokong, Tebello
- Authors: Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188639 , vital:44771 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.04.015"
- Description: This work reports on the conjugation of semiconductors quantum dots (QDs), gold (AuNPs) or Fe3O4 magnetic (MNPs) nanoparticles to 4-(4,6-diaminopyrimidin-2-ylthio) substituted indium or zinc phthalocyanines (Pcs). The QDs and MNPs were linked to the Pcs via an amide bond and by chemisorption unto AuNP surface. There is a general decrease in fluorescence quantum yields of the Pcs in the presence of all the nanoparticles. There is an increase triplet quantum yields for Pcs in the presence of AuNPs and QDs, but not in the presence of MNPs. AuNPs conjugates irrespective of the central atoms have the highest singlet oxygen quantum yield and are more photo-stable than all the other conjugates. MPcs are less photostable in the presence of MNPs.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188639 , vital:44771 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.04.015"
- Description: This work reports on the conjugation of semiconductors quantum dots (QDs), gold (AuNPs) or Fe3O4 magnetic (MNPs) nanoparticles to 4-(4,6-diaminopyrimidin-2-ylthio) substituted indium or zinc phthalocyanines (Pcs). The QDs and MNPs were linked to the Pcs via an amide bond and by chemisorption unto AuNP surface. There is a general decrease in fluorescence quantum yields of the Pcs in the presence of all the nanoparticles. There is an increase triplet quantum yields for Pcs in the presence of AuNPs and QDs, but not in the presence of MNPs. AuNPs conjugates irrespective of the central atoms have the highest singlet oxygen quantum yield and are more photo-stable than all the other conjugates. MPcs are less photostable in the presence of MNPs.
- Full Text:
- Date Issued: 2016
Synthesis and singlet oxygen production by a phthalocyanine when embedded in asymmetric polymer membranes
- Mafukidze, Donovan M, Mashazi, Philani N, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188563 , vital:44765 , xlink:href="https://doi.org/10.1016/j.polymer.2016.10.032"
- Description: 2(3), 9(10), 16(17), 23(24)-Tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (ClInTAPPc, 3) was first conjugated to two different polymers: polystyrene (PS) and polyacrylonitrile (PAN) to form 3-PS and 3-PAN. The conjugates were cast into the corresponding polymers to form membranes represented as 3-PS-membrane and 3-PAN-membrane, respectively. The prepared membranes were characterized using various techniques including scanning electron microscopy and solid state UV/Vis spectroscopy. Singlet oxygen quantum yields were higher for the 3-PS-membrane at 0.51 compared to 3-PAN-membrane at 0.35. The larger singlet oxygen also applies to 3-PS (0.63) compared to 3-PAN (0.38) when in solution.
- Full Text:
- Date Issued: 2016
- Authors: Mafukidze, Donovan M , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188563 , vital:44765 , xlink:href="https://doi.org/10.1016/j.polymer.2016.10.032"
- Description: 2(3), 9(10), 16(17), 23(24)-Tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (ClInTAPPc, 3) was first conjugated to two different polymers: polystyrene (PS) and polyacrylonitrile (PAN) to form 3-PS and 3-PAN. The conjugates were cast into the corresponding polymers to form membranes represented as 3-PS-membrane and 3-PAN-membrane, respectively. The prepared membranes were characterized using various techniques including scanning electron microscopy and solid state UV/Vis spectroscopy. Singlet oxygen quantum yields were higher for the 3-PS-membrane at 0.51 compared to 3-PAN-membrane at 0.35. The larger singlet oxygen also applies to 3-PS (0.63) compared to 3-PAN (0.38) when in solution.
- Full Text:
- Date Issued: 2016
Synthesis and structural studies of NiS and PdS nanoparticles/nanocomposites from dithiocarbamates single source precursors
- Authors: Nqombolo, Azile
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11359 , http://hdl.handle.net/10353/d1021326
- Description: The main aim of this research is to synthesize Ni(II) and Pd(II) dithiocarbamate complexes and use them as single source precursors for the synthesis of NiS and PdS nanoparticles and metal sulphides potato starch nanocomposites. Four dithiocarbamate ligands were synthesized and characterized using elemental analysis and spectroscopic techniques. The ligands were used to prepared homoleptic Ni(II) and Pd(II) complexes of the dithiocarbamate ligands. The metal complexes were characterized with elemental analysis, UV-Vis, FTIR and 1H-NMR spectroscopic techniques. Conductivity measurements indicate that all the complexes are non-electrolytes in solution and results from the electronic spectra studies confirmed the proposed 4-coordinate square planar geometry around the metal ions. The nickel complexes showed d-d transitions around 477 nm while in the palladium complexes, no d-d transitions were observed but the compounds showed strong metal to ligand charge transfer transitions. From the FTIR spectra studies, it can be confirmed that the complexes were successfully synthesised because all peaks of interest were observed at expected regions from the literature. The νC-N was observed around 1469-1495 cm-1, νC=S around 1101-1188 cm-1 and νC-S around 738-1060 cm-1 for both Ni(II) and Pd(II) complexes. νNi-S was observed around 375-543 cm-1 and νPd-S around 529-545 cm-1. The FTIR also confirmed that the dithiocarbamate ligands act as bidentate chelating ligands through the sulfur atoms. The complexes were used as single source precursors and thermolysed in hexadecylamine (HDA) at 220 °C to prepare four HDA-capped nickel sulfide nanoparticles and four palladium sulfide nanoparticles. The as-prepared nanoparticles were studied with optical absorption spectra, photoluminescence, powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The optical studies results showed that NiS have large band gaps that are greater than that of the bulk, therefore they are found to be blue shifted relative to the bulk, which shows that they have small particle size and thus confirming their quantum confinement effect. PL spectra reveal that the emission peaks are red shifted compared to the absorption band edges of the nanoparticles. The XRD patterns confirmed the formation of cubic and rhombohedral phase for NiS nanoparticles and cubic phase for PdS nanoparticles. SEM images of both NiS and PdS show uniform surface morphology at low and high magnification with different shapes. EDS analyses confirmed the presence of Ni, S, and Pd in each of the spectrum indicating that the nanoparticles were successfully synthesized. TEM images showed that the synthesised nanoparticles have uniform and narrow size distribution with no agglomeration. The sizes of the NiS nanoparticles were found to be in the range of 12-38 nm for NiS1, 8-11 nm for NiS2, 9-16 nm for NiS3 and 4-9 nm for NiS4. The TEM images for the as-prepared PdS nanoparticles showed that the average crystallite sizes are 6.94-9.62 nm for PdS1, 8-11 nm for PdS2, 9-16 nm for PdS3 and 4-9 nm for PdS4 respectively. The nanoparticles were used to prepare potato starch nanocomposites and SEM images indicate that the surface morphology of starch polymer nanocomposites compose of potato starch and few particles in between the pores of the matrix, this is due to the small ratio of nanoparticles used.
- Full Text:
- Date Issued: 2016
- Authors: Nqombolo, Azile
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11359 , http://hdl.handle.net/10353/d1021326
- Description: The main aim of this research is to synthesize Ni(II) and Pd(II) dithiocarbamate complexes and use them as single source precursors for the synthesis of NiS and PdS nanoparticles and metal sulphides potato starch nanocomposites. Four dithiocarbamate ligands were synthesized and characterized using elemental analysis and spectroscopic techniques. The ligands were used to prepared homoleptic Ni(II) and Pd(II) complexes of the dithiocarbamate ligands. The metal complexes were characterized with elemental analysis, UV-Vis, FTIR and 1H-NMR spectroscopic techniques. Conductivity measurements indicate that all the complexes are non-electrolytes in solution and results from the electronic spectra studies confirmed the proposed 4-coordinate square planar geometry around the metal ions. The nickel complexes showed d-d transitions around 477 nm while in the palladium complexes, no d-d transitions were observed but the compounds showed strong metal to ligand charge transfer transitions. From the FTIR spectra studies, it can be confirmed that the complexes were successfully synthesised because all peaks of interest were observed at expected regions from the literature. The νC-N was observed around 1469-1495 cm-1, νC=S around 1101-1188 cm-1 and νC-S around 738-1060 cm-1 for both Ni(II) and Pd(II) complexes. νNi-S was observed around 375-543 cm-1 and νPd-S around 529-545 cm-1. The FTIR also confirmed that the dithiocarbamate ligands act as bidentate chelating ligands through the sulfur atoms. The complexes were used as single source precursors and thermolysed in hexadecylamine (HDA) at 220 °C to prepare four HDA-capped nickel sulfide nanoparticles and four palladium sulfide nanoparticles. The as-prepared nanoparticles were studied with optical absorption spectra, photoluminescence, powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The optical studies results showed that NiS have large band gaps that are greater than that of the bulk, therefore they are found to be blue shifted relative to the bulk, which shows that they have small particle size and thus confirming their quantum confinement effect. PL spectra reveal that the emission peaks are red shifted compared to the absorption band edges of the nanoparticles. The XRD patterns confirmed the formation of cubic and rhombohedral phase for NiS nanoparticles and cubic phase for PdS nanoparticles. SEM images of both NiS and PdS show uniform surface morphology at low and high magnification with different shapes. EDS analyses confirmed the presence of Ni, S, and Pd in each of the spectrum indicating that the nanoparticles were successfully synthesized. TEM images showed that the synthesised nanoparticles have uniform and narrow size distribution with no agglomeration. The sizes of the NiS nanoparticles were found to be in the range of 12-38 nm for NiS1, 8-11 nm for NiS2, 9-16 nm for NiS3 and 4-9 nm for NiS4. The TEM images for the as-prepared PdS nanoparticles showed that the average crystallite sizes are 6.94-9.62 nm for PdS1, 8-11 nm for PdS2, 9-16 nm for PdS3 and 4-9 nm for PdS4 respectively. The nanoparticles were used to prepare potato starch nanocomposites and SEM images indicate that the surface morphology of starch polymer nanocomposites compose of potato starch and few particles in between the pores of the matrix, this is due to the small ratio of nanoparticles used.
- Full Text:
- Date Issued: 2016
Synthesis of chiral ketopinic acid-derived catalysts and their evaluation in asymmetric transformations
- Authors: Hassan, Yusuf
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/550 , vital:19969
- Description: Four new (+)-ketopinic acid-derived Mn(III) complexes, three of which possess pseudo C2- symmetry, were synthesised as chiral catalyst candidates. The ligands were prepared by refluxing (+)-ketopinic acid with ethane-1,2-diamine, the resolved (R,R)- and (S,S)-1,2-diaminocyclohexanes, and 1,2-diaminobenzene in chloroform. Treatment of the ligands with manganese(II) acetate tetrahydrate in refluxing ethanol afforded the respective complexes as brown amorphous powders. Characterisation of the ligands and the corresponding complexes was achieved using 1-D and 2-D NMR, IR spectroscopy, and elemental analysis. Various homogeneous asymmetric transformations, were investigated using these four complexes, viz., aldol, and Baylis-Hillman reactions, aza-Michael addition of piperidine to the Baylis-Hillman adducts, epoxidation, and ketone and imine reduction. Asymmetric aldol reactions of benzaldehyde with the aryl ketones, acetophenone, propiophenone, -tetralone, 4-nitroacetophenone, and 4-methoxyacetophenone, conducted in the presence of 10 mole % of the chiral catalysts, afforded enantioselectivities of up to 99% e.e. Asymmetric Baylis-Hillman reactions of methyl- and tert-butyl acrylates with pyridine-2- carbaldehyde, 6-methylpyridine-2-carbaldehyde, 5-chlorosalicylaldehyde, benzaldehyde, 4-chlorobenzaldehyde, and 2-nitrobenzaldehyde were conducted in the presence of catalyst 139 (10 mole %) to afford enantioselectivities of up to 44% e.e. Aza-Michael addition of piperidine to racemic Baylis- Hillman adducts in the presence of the catalyst 139 (10 mole %) was found to proceed with diastereoselectivities of up to 91% d.e. Asymmetric epoxidation of trans-methyl styrene, styrene, trans-stilbene, cis-stilbene, and indene, using a 5 mole % chiral catalyst loading and m-CPBA as the oxygen source, gave enantioselectivities of up to 32 % e.e. Asymmetric reductions of acetophenone, 3-chloropropiophenone, 4-hydroxyacetophenone, -tetralone, and 2-hydroxy-1-acetonapthone were investigated using NaBH4 as the reducing agent and a 10 mole % loading of the chiral catalysts. A stereoselectivity of 68% e.e. was obtained in the reduction of acetophenone, but attempts to reduce the selected imines to the corresponding chiral amines proved to be unsuccessful — even in the absence of the catalysts. It thus became apparent that the catalytic version of the reaction was not feasible.
- Full Text:
- Date Issued: 2016
- Authors: Hassan, Yusuf
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/550 , vital:19969
- Description: Four new (+)-ketopinic acid-derived Mn(III) complexes, three of which possess pseudo C2- symmetry, were synthesised as chiral catalyst candidates. The ligands were prepared by refluxing (+)-ketopinic acid with ethane-1,2-diamine, the resolved (R,R)- and (S,S)-1,2-diaminocyclohexanes, and 1,2-diaminobenzene in chloroform. Treatment of the ligands with manganese(II) acetate tetrahydrate in refluxing ethanol afforded the respective complexes as brown amorphous powders. Characterisation of the ligands and the corresponding complexes was achieved using 1-D and 2-D NMR, IR spectroscopy, and elemental analysis. Various homogeneous asymmetric transformations, were investigated using these four complexes, viz., aldol, and Baylis-Hillman reactions, aza-Michael addition of piperidine to the Baylis-Hillman adducts, epoxidation, and ketone and imine reduction. Asymmetric aldol reactions of benzaldehyde with the aryl ketones, acetophenone, propiophenone, -tetralone, 4-nitroacetophenone, and 4-methoxyacetophenone, conducted in the presence of 10 mole % of the chiral catalysts, afforded enantioselectivities of up to 99% e.e. Asymmetric Baylis-Hillman reactions of methyl- and tert-butyl acrylates with pyridine-2- carbaldehyde, 6-methylpyridine-2-carbaldehyde, 5-chlorosalicylaldehyde, benzaldehyde, 4-chlorobenzaldehyde, and 2-nitrobenzaldehyde were conducted in the presence of catalyst 139 (10 mole %) to afford enantioselectivities of up to 44% e.e. Aza-Michael addition of piperidine to racemic Baylis- Hillman adducts in the presence of the catalyst 139 (10 mole %) was found to proceed with diastereoselectivities of up to 91% d.e. Asymmetric epoxidation of trans-methyl styrene, styrene, trans-stilbene, cis-stilbene, and indene, using a 5 mole % chiral catalyst loading and m-CPBA as the oxygen source, gave enantioselectivities of up to 32 % e.e. Asymmetric reductions of acetophenone, 3-chloropropiophenone, 4-hydroxyacetophenone, -tetralone, and 2-hydroxy-1-acetonapthone were investigated using NaBH4 as the reducing agent and a 10 mole % loading of the chiral catalysts. A stereoselectivity of 68% e.e. was obtained in the reduction of acetophenone, but attempts to reduce the selected imines to the corresponding chiral amines proved to be unsuccessful — even in the absence of the catalysts. It thus became apparent that the catalytic version of the reaction was not feasible.
- Full Text:
- Date Issued: 2016
Synthesis, characterization and electrochemistry of rhodium (iii) complexes of meso-substituted [14] tribenzotriphyrin (2.1. 1)
- Xue, Zhaoli, Wang, Yemei, Mack, John, Mkhize, Scebi, Nyokong, Tebello, Fang, Yuanyuan, Ou, Zhongping, Kadish, Karl M
- Authors: Xue, Zhaoli , Wang, Yemei , Mack, John , Mkhize, Scebi , Nyokong, Tebello , Fang, Yuanyuan , Ou, Zhongping , Kadish, Karl M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241043 , vital:50899 , xlink:href="https://doi.org/10.1039/C6RA03028A"
- Description: A thermal reaction using a series of [14]tribenzotriphyrins(2.1.1) (TriPs, 1a–d) with Rh2(C8H12)Cl2 provides RhIII–TriP complexes (2a–d) in 40−52% yields. The complexes were characterized by mass spectrometry, UV-visible absorption and 1H NMR spectroscopy. Single crystal X-ray analysis reveals that 2b adopts a dome-shaped conformation. The rhodium(III) ion is coordinated by the three pyrrole nitrogen atoms, two chloride ions and the nitrogen atom of an acetonitrile (CH3CN) solvent molecule. The optical spectra can be assigned using Michl's perimeter model. The L and B bands of the 2a–d complexes lie at ca. 600 and 500 nm, respectively, and are markedly red shifted relative to those of 1a–d. A reversible one-electron oxidation and two reversible one-electron reductions are observed in the cyclic voltammograms of 2a–d in CH2Cl2. The redox potentials are consistent with the optical data and the relatively narrow HOMO–LUMO gaps that are predicted in DFT calculations. TD-DFT calculations have been used to assign a third intense spectral band at 375 nm to a higher energy π → π* transition of the [14]tribenzotriphyrin(2.1.1) π-system.
- Full Text:
- Date Issued: 2016
- Authors: Xue, Zhaoli , Wang, Yemei , Mack, John , Mkhize, Scebi , Nyokong, Tebello , Fang, Yuanyuan , Ou, Zhongping , Kadish, Karl M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241043 , vital:50899 , xlink:href="https://doi.org/10.1039/C6RA03028A"
- Description: A thermal reaction using a series of [14]tribenzotriphyrins(2.1.1) (TriPs, 1a–d) with Rh2(C8H12)Cl2 provides RhIII–TriP complexes (2a–d) in 40−52% yields. The complexes were characterized by mass spectrometry, UV-visible absorption and 1H NMR spectroscopy. Single crystal X-ray analysis reveals that 2b adopts a dome-shaped conformation. The rhodium(III) ion is coordinated by the three pyrrole nitrogen atoms, two chloride ions and the nitrogen atom of an acetonitrile (CH3CN) solvent molecule. The optical spectra can be assigned using Michl's perimeter model. The L and B bands of the 2a–d complexes lie at ca. 600 and 500 nm, respectively, and are markedly red shifted relative to those of 1a–d. A reversible one-electron oxidation and two reversible one-electron reductions are observed in the cyclic voltammograms of 2a–d in CH2Cl2. The redox potentials are consistent with the optical data and the relatively narrow HOMO–LUMO gaps that are predicted in DFT calculations. TD-DFT calculations have been used to assign a third intense spectral band at 375 nm to a higher energy π → π* transition of the [14]tribenzotriphyrin(2.1.1) π-system.
- Full Text:
- Date Issued: 2016
Synthesis, Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems
- Okujima, Tetsuo, Mack, John, Nakamura, Jun, Kubheka, Gugu, Nyokong, Tebello, Zhu, Hua, Komobuchi, Naoki, Ono, Noboru, Yamada, Hiroko, Uno, Hidemitsu, Kobayashi, Nagao
- Authors: Okujima, Tetsuo , Mack, John , Nakamura, Jun , Kubheka, Gugu , Nyokong, Tebello , Zhu, Hua , Komobuchi, Naoki , Ono, Noboru , Yamada, Hiroko , Uno, Hidemitsu , Kobayashi, Nagao
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240360 , vital:50827 , xlink:href="https://doi.org/10.1002/chem.201602213"
- Description: A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro-Diels–Alder reaction of bicyclo[2.2.2]octadiene-fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time-dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π-molecular orbitals.
- Full Text:
- Date Issued: 2016
- Authors: Okujima, Tetsuo , Mack, John , Nakamura, Jun , Kubheka, Gugu , Nyokong, Tebello , Zhu, Hua , Komobuchi, Naoki , Ono, Noboru , Yamada, Hiroko , Uno, Hidemitsu , Kobayashi, Nagao
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240360 , vital:50827 , xlink:href="https://doi.org/10.1002/chem.201602213"
- Description: A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro-Diels–Alder reaction of bicyclo[2.2.2]octadiene-fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time-dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π-molecular orbitals.
- Full Text:
- Date Issued: 2016
Synthesis, spectroscopic and nonlinear optical properties of metal-free and nickel β substituted binuclear phthalocyanines
- Authors: Kabwe, Kapambwe Peter
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3013 , vital:20352
- Description: In this project, nickel and metal-free 4β-(4-tert-butylphenoxy) phthalocyanine, biphenyl bridged binuclear 4-tert-butylphenoxy phthalocyanine and naphthalene bridged binuclear 4-tert-butylphenoxy phthalocyanine have been synthesised. The Z-scan technique has been employed to comparatively study their second order nonlinear optical (NLO) properties. This work, shows that the presence of H-aggregation in binuclear Pcs of metal-free and nickel 4β-(4-tertbutylphenoxy) phthalocyanines do not have an effect on the magnitude of second order nonlinear absorption coefficient (β) as compared to monomeric Pcs. Density functional (DFT) calculations of dipolar/octupolar contributions were performed, in order to explain experimentally determined β values. Spectroscopic and photophysical properties of the synthesised compounds have been determined using a range of different spectroscopic techniques, including magnetic circular dichroism (MCD), time correlated single photon counting spectroscopy (TCSPC), UV-visible absorption spectroscopy, mass spectroscopy and IR Spectroscopy.
- Full Text:
- Date Issued: 2016
- Authors: Kabwe, Kapambwe Peter
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3013 , vital:20352
- Description: In this project, nickel and metal-free 4β-(4-tert-butylphenoxy) phthalocyanine, biphenyl bridged binuclear 4-tert-butylphenoxy phthalocyanine and naphthalene bridged binuclear 4-tert-butylphenoxy phthalocyanine have been synthesised. The Z-scan technique has been employed to comparatively study their second order nonlinear optical (NLO) properties. This work, shows that the presence of H-aggregation in binuclear Pcs of metal-free and nickel 4β-(4-tertbutylphenoxy) phthalocyanines do not have an effect on the magnitude of second order nonlinear absorption coefficient (β) as compared to monomeric Pcs. Density functional (DFT) calculations of dipolar/octupolar contributions were performed, in order to explain experimentally determined β values. Spectroscopic and photophysical properties of the synthesised compounds have been determined using a range of different spectroscopic techniques, including magnetic circular dichroism (MCD), time correlated single photon counting spectroscopy (TCSPC), UV-visible absorption spectroscopy, mass spectroscopy and IR Spectroscopy.
- Full Text:
- Date Issued: 2016
Systemic influences on the career development of a sample of black South African adolescent females: adolescent and parental perspectives
- Stolarczyk, Elizabeth Maria, McMahon, Mary
- Authors: Stolarczyk, Elizabeth Maria , McMahon, Mary
- Date: 2016
- Subjects: Career development -- Women -- South Africa , Counseling -- Women -- South Africa , Vocational guidance -- Women -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12865 , vital:27128
- Description: Career counselling in South Africa is yet fully support the transformation process taking place nationally. More specifically, the discipline of career psychology requires the emergence of a career development theory commensurate with its diverse population. historically, extensive use was made of western career theories which were not applicable to the majority of South Africa's culturally and ethically diverse population groups consisting predominantly of black individuals of low socioeconomic status. In addition, since 1994 a black middle class has emerged in South Africa that has become increasingly prominent. Familial and parental influence on the career development of adolescents is acknowledge as pivotal; however, little South Afriucan research exists on this topic. The aim of the present study is to investigate the systematic influence on adolescent career development from the perspectives of black South African middle class grade 11 females and their parents.
- Full Text:
- Date Issued: 2016
- Authors: Stolarczyk, Elizabeth Maria , McMahon, Mary
- Date: 2016
- Subjects: Career development -- Women -- South Africa , Counseling -- Women -- South Africa , Vocational guidance -- Women -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12865 , vital:27128
- Description: Career counselling in South Africa is yet fully support the transformation process taking place nationally. More specifically, the discipline of career psychology requires the emergence of a career development theory commensurate with its diverse population. historically, extensive use was made of western career theories which were not applicable to the majority of South Africa's culturally and ethically diverse population groups consisting predominantly of black individuals of low socioeconomic status. In addition, since 1994 a black middle class has emerged in South Africa that has become increasingly prominent. Familial and parental influence on the career development of adolescents is acknowledge as pivotal; however, little South Afriucan research exists on this topic. The aim of the present study is to investigate the systematic influence on adolescent career development from the perspectives of black South African middle class grade 11 females and their parents.
- Full Text:
- Date Issued: 2016
Taking gendered harms seriously : the utility of rape trauma syndrome evidence in dispelling rape myths in criminal trials
- Authors: Nkala, Amanda Nothabo
- Date: 2016
- Subjects: Rape trauma syndrome Women -- Crimes against Rape -- Psychological aspects
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10353/13458 , vital:39668
- Description: Rape is a violent crime marked by underreporting and low conviction rates. Notwithstanding the fact that most rape laws have been made to be gender-neutral, the statistics of rape are still devastatingly high even on a global scale. The majority of the victims are still predominantly females especially in the context of acquaintance rape. It is an uncontestable fact that rape usually occurs in secret making it possible for one to falsely accuse another and effectively rendering it difficult to refute. In light of this, victims who have managed to reach the courts have come face to face with a myriad of stereotypical beliefs and rape myths about rape victims. These have dealt a blow to their cases once their credibility is doubted because they may have exhibited behaviour that does not match with the classic or real rape victim as expected by the society. However rape is an egregiously unique crime that presents with serious psychological issues for the victim. As such it is possible for a rape victim to exhibit counterintuitive behaviour that can only be sensibly explained by an expert who has delved in human behavioural sciences. The alleged victim will be questioned on things like lengthy delay in reporting, returning to the scene of the crime, asking for taxi money the morning after the rape or even failing to scream and fight off the alleged assailant. Unfortunately, the psychological effects of rape have more often than not been overlooked in our criminal justice system giving way for blame shifting in that the female victim is called upon to account for why the rape may have happened to her. These psychological reactions, responses and counterintuitive behaviour have been characterized as Rape Trauma Syndrome by specialists in psychology and psychiatry. In the context of this study, Rape Trauma Syndrome is a form of expert opinion evidence which is relevant, helpful and necessary because it can dispel rape myths and stereotypical beliefs about rape victims by educating the courts about the psychological reactions of rape victims. Against this backdrop, this research project investigates the utility of Rape Trauma Syndrome evidence in dispelling rape myths in rape trials, focusing especially on the admissibility and use of that syndrome as evidence in other jurisdictions at the level of comparative analysis in order to establish whether it can be utilised in the South African context.
- Full Text:
- Date Issued: 2016
- Authors: Nkala, Amanda Nothabo
- Date: 2016
- Subjects: Rape trauma syndrome Women -- Crimes against Rape -- Psychological aspects
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10353/13458 , vital:39668
- Description: Rape is a violent crime marked by underreporting and low conviction rates. Notwithstanding the fact that most rape laws have been made to be gender-neutral, the statistics of rape are still devastatingly high even on a global scale. The majority of the victims are still predominantly females especially in the context of acquaintance rape. It is an uncontestable fact that rape usually occurs in secret making it possible for one to falsely accuse another and effectively rendering it difficult to refute. In light of this, victims who have managed to reach the courts have come face to face with a myriad of stereotypical beliefs and rape myths about rape victims. These have dealt a blow to their cases once their credibility is doubted because they may have exhibited behaviour that does not match with the classic or real rape victim as expected by the society. However rape is an egregiously unique crime that presents with serious psychological issues for the victim. As such it is possible for a rape victim to exhibit counterintuitive behaviour that can only be sensibly explained by an expert who has delved in human behavioural sciences. The alleged victim will be questioned on things like lengthy delay in reporting, returning to the scene of the crime, asking for taxi money the morning after the rape or even failing to scream and fight off the alleged assailant. Unfortunately, the psychological effects of rape have more often than not been overlooked in our criminal justice system giving way for blame shifting in that the female victim is called upon to account for why the rape may have happened to her. These psychological reactions, responses and counterintuitive behaviour have been characterized as Rape Trauma Syndrome by specialists in psychology and psychiatry. In the context of this study, Rape Trauma Syndrome is a form of expert opinion evidence which is relevant, helpful and necessary because it can dispel rape myths and stereotypical beliefs about rape victims by educating the courts about the psychological reactions of rape victims. Against this backdrop, this research project investigates the utility of Rape Trauma Syndrome evidence in dispelling rape myths in rape trials, focusing especially on the admissibility and use of that syndrome as evidence in other jurisdictions at the level of comparative analysis in order to establish whether it can be utilised in the South African context.
- Full Text:
- Date Issued: 2016
Tanzania's development agenda and poverty reduction : a case of Mkukuta I1
- Authors: Mandalu, Martin Petro
- Date: 2016
- Subjects: Poverty--Tanzania Tanzania--Economic conditions
- Language: English
- Type: Thesis , Doctoral , Development Studies
- Identifier: http://hdl.handle.net/10353/15616 , vital:40487
- Description: Poverty reduction has always been part of Tanzania‘s development agenda since independence in 1961. Despite wealth of natural resources, peace and political stability, the country has continued to be poor for decades. A number of strategies have been employed to address the problem; however, they have not been so successful. Studies have explored the problem and came up with explanations that are insufficient. In recent years, more studies on poverty reduction increased, following the country‘s magnificent economic growth which, however, fails to alleviate poverty in the country. Recent literature on poverty reduction calls for improvement in the productive sectors such as agriculture and construction to increase their contribution in poverty reduction. However, most studies did not pay attention to the development model/s that led the economy since independence. Motivated by the unsatisfactory results of the previous poverty reduction strategies, and lacunas of the preceding studies, this research, through MKUKUTA I, examines factors affecting the development agenda in Tanzania and their influence on poverty reduction. It investigates, as well, the development models employed in the country since independence. The study is guided by the change of development theories: from socialism to neo-liberalism. Furthermore, the study proposes an alternative development model beyond dependency and neo-liberalism schools of thoughts that have been struggling to influence development in the country for over five decades. The study employs mainly secondary data and primary data as supplementary methods to analyse and explain the mismatch between economic growth and poverty reduction in the country. The study argues that the productive sectors fail to produce sufficiently and contribute to poverty reduction since they are not guided by any specific development model. Findings suggest that failure in poverty reduction despite remarkable economic growth is caused by failure of growth in the agriculture sector which employs the largest part of the workforce in the country. Economic transformation in the country, which contributed to economic growth, failed to generate more jobs in the productive sectors. Incorrect methodologies used for obtaining economic data are alleged as possible logical explanation for the mismatch between economic growth and failure in poverty reduction. Failure in poverty reduction had a negative impact on human development as the poor, especially in the rural areas, had limited access to quality services of education, health care, water and sanitation. Moreover, findings revealed that neoliberal policies in the country are not effective enough in guiding the development agenda and poverty reduction. Despite the rule of law, peace, political stability and favourable conditions for capitalism in the country, significant features of a neoliberal economy have not been effectively developed. The local private sector is still weak at the embryonic stage, and the market is weakened by corruption and poor infrastructure for doing business. Moreover, findings suggest that for about three decades, Tanzania has not had a clear and distinct development model to guide its development agenda in poverty alleviation. The constitution suggests that the country is guided by a socialist development philosophy whereas the official government website and practices indicate that the country is run by neoliberal policies. To resolve the matter and in view of attaining the TDV 2025 and poverty reduction, this study proposes that Tanzania becomes a democratic developmental state while governed by a dependency-neoliberal theory from the amalgamation of reviewed dependency and neo-liberal schools of thoughts as a guiding principle since all developmental states need guiding philosophies to lead them. Moreover, the study proposes pragmatic interventions to implement the development model.
- Full Text:
- Date Issued: 2016
- Authors: Mandalu, Martin Petro
- Date: 2016
- Subjects: Poverty--Tanzania Tanzania--Economic conditions
- Language: English
- Type: Thesis , Doctoral , Development Studies
- Identifier: http://hdl.handle.net/10353/15616 , vital:40487
- Description: Poverty reduction has always been part of Tanzania‘s development agenda since independence in 1961. Despite wealth of natural resources, peace and political stability, the country has continued to be poor for decades. A number of strategies have been employed to address the problem; however, they have not been so successful. Studies have explored the problem and came up with explanations that are insufficient. In recent years, more studies on poverty reduction increased, following the country‘s magnificent economic growth which, however, fails to alleviate poverty in the country. Recent literature on poverty reduction calls for improvement in the productive sectors such as agriculture and construction to increase their contribution in poverty reduction. However, most studies did not pay attention to the development model/s that led the economy since independence. Motivated by the unsatisfactory results of the previous poverty reduction strategies, and lacunas of the preceding studies, this research, through MKUKUTA I, examines factors affecting the development agenda in Tanzania and their influence on poverty reduction. It investigates, as well, the development models employed in the country since independence. The study is guided by the change of development theories: from socialism to neo-liberalism. Furthermore, the study proposes an alternative development model beyond dependency and neo-liberalism schools of thoughts that have been struggling to influence development in the country for over five decades. The study employs mainly secondary data and primary data as supplementary methods to analyse and explain the mismatch between economic growth and poverty reduction in the country. The study argues that the productive sectors fail to produce sufficiently and contribute to poverty reduction since they are not guided by any specific development model. Findings suggest that failure in poverty reduction despite remarkable economic growth is caused by failure of growth in the agriculture sector which employs the largest part of the workforce in the country. Economic transformation in the country, which contributed to economic growth, failed to generate more jobs in the productive sectors. Incorrect methodologies used for obtaining economic data are alleged as possible logical explanation for the mismatch between economic growth and failure in poverty reduction. Failure in poverty reduction had a negative impact on human development as the poor, especially in the rural areas, had limited access to quality services of education, health care, water and sanitation. Moreover, findings revealed that neoliberal policies in the country are not effective enough in guiding the development agenda and poverty reduction. Despite the rule of law, peace, political stability and favourable conditions for capitalism in the country, significant features of a neoliberal economy have not been effectively developed. The local private sector is still weak at the embryonic stage, and the market is weakened by corruption and poor infrastructure for doing business. Moreover, findings suggest that for about three decades, Tanzania has not had a clear and distinct development model to guide its development agenda in poverty alleviation. The constitution suggests that the country is guided by a socialist development philosophy whereas the official government website and practices indicate that the country is run by neoliberal policies. To resolve the matter and in view of attaining the TDV 2025 and poverty reduction, this study proposes that Tanzania becomes a democratic developmental state while governed by a dependency-neoliberal theory from the amalgamation of reviewed dependency and neo-liberal schools of thoughts as a guiding principle since all developmental states need guiding philosophies to lead them. Moreover, the study proposes pragmatic interventions to implement the development model.
- Full Text:
- Date Issued: 2016
Teacher code switching consistency and precision in a multilingual mathematics classroom:
- Chikiwa, Clemence, Schäfer, Marc
- Authors: Chikiwa, Clemence , Schäfer, Marc
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141087 , vital:37943 , https://doi.org/10.1080/18117295.2016.1228823
- Description: This paper reports on a study that investigated teacher code switching consistency and precision in multilingual secondary school mathematics classrooms in South Africa. Data was obtained through interviewing and observing five lessons of each of three mathematics teachers purposively selected from three township schools in the Eastern Cape Province. Elements of Gumperz and Mercer’s work on lesson categories and Dowling’s Domains of Mathematical Practice were used to analyse data. Results showed that code switching frequency in general was inconsistent across different lessons for the same teacher.
- Full Text:
- Date Issued: 2016
- Authors: Chikiwa, Clemence , Schäfer, Marc
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141087 , vital:37943 , https://doi.org/10.1080/18117295.2016.1228823
- Description: This paper reports on a study that investigated teacher code switching consistency and precision in multilingual secondary school mathematics classrooms in South Africa. Data was obtained through interviewing and observing five lessons of each of three mathematics teachers purposively selected from three township schools in the Eastern Cape Province. Elements of Gumperz and Mercer’s work on lesson categories and Dowling’s Domains of Mathematical Practice were used to analyse data. Results showed that code switching frequency in general was inconsistent across different lessons for the same teacher.
- Full Text:
- Date Issued: 2016