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The aim of the study was to heterogenise existing tetramerisation catalysts by supporting the bis(diphenylphosphino)amine ligands on polymer. The polymer of choice was Merrifield’s resin which was functionalized to enable attachment of the ligands. These supported ligands were characterized via ATR, solid-state NMR, SEM and TGA-DSC. In order to compare activity of the supported and unsupported ligands, homogeneous bis(diphenylphosphino)amine ligands were synthesized and characterized via NMR, elemental Analysis, ATR and GC-MS. Tetramerisation reactions were carried out in a Parr pressure reactor using Cr(acac)₃as the precursor and MMAO-3A as the activator. The homogeneous ligands proved active in the tetramerisation of ethylene, with the selectivity of 1-octene in the C8 fraction being comparable with that mentioned in literature (> 98 wt%). When comparing the homogeneous ligands with their heterogeneous counterparts, the heterogeneous ligands performed poorly due to steric effects caused by the polymer chain. The activity dropped by more than four times that of their homogeneous counterparts and the selectivity towards the main product, 1-octene, was very low (< 10 wt%). These ligands seemed to create a system that favoured the formation of the C6 products more than any other product, with the C6 cyclics being the most dominant. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

The principal goal of this work was to synthesize and fully characterize a range of free / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

A number of ligands that belong to the salen-type family were synthesized in this thesis. These ligands were synthesized from salicylaldehyde and 1,2-phenylenediamine, 1,3- diamino-2-hydroxypropane, 1,2-diamino-ethane, N-(3-aminopropyl)-1,3-propanediamine, diethylenetriamine, diaminomaleonitrile, 2,2-dimethyl-1,3-propanediamine and 1,3- diaminopropane. From this range of ligands, H2salophen was chosen as the ligand for further studies. This work is aimed primarily at elucidating the structures and spectroscopic properties of [Co(salophen)(amine)2](OAc) derivatives, where salophen is N,N’-disalicylidene-1,2- phenylenediamine and the amines used were butylamine, benzylamine, a- methylbenzylamine, dibutylamine, N-methylpiperazine and piperidine. Three novel crystal structures of [CoIII(salophen)L2]Cl derivatives, where L = butylamine, benzylamine, and piperidine, with Co-N distances that range from 1.901 Å to 2.024 Å, have been reported in this thesis. The novel crystal structure of [Co(salophen)(N-MePipz)(OAc)] is also reported in this thesis. These cobalt complexes have been analysed by 1H, 13C and 59Co NMR as well as electronic and IR spectroscopy. A 59Co NMR spectrum was obtained for the [Co(salophen)(BuNH2)2]CH2Cl2×Cl complex. The spectrum exhibits a single line at 8504 ppm. The binding constants of all [Co(salophen)(amine)2](OAc) complexes, where amine = butylamine, benzylamine, a-methylbenzylamine, dibutylamine, N-methylpiperazine and piperidine, were determined by spectroscopic titrations. The titrations were carried out at various concentrations of the amine and at temperatures ranging from 25°C to 45°C. It was found that the primary amines had much larger values of K1 and K2 compared to the secondary amines. Typical values of K1 and K2 were 8000 M-1 and 63.6 M-1 respectively at 25°C, for a-methylbenzylamine. Of the primary amines, it was found that a- methylbenzylamine had the largest value of K1 and K2 compared to the other two amines. For the secondary amines, it was found that N-methylpiperazine had the bigger value of K1 compared to that of dibutylamine. / Thesis (M.Sc. )-University of KwaZulu-Natal, Pietermaritzburg, 2007.

The synthesis, characterisation and X-ray structure detenninations of homonuclear nickel, palladium and platinum complexes with bis(phosphino)amine ligands is reviewed in Chapter 1. Particular attention is given to the mode of coordination that these ligands may adopt when coordinating to a transition metal i.e., as a monodentate (n'-), chelating (n2-) or bridging (u-) ligand. The Chapter is concluded with a brief summary of (i) The dependence of the 31P chemical shift for the bonded phosphorus atom(s) on the mode of coordination and (ii) The dependence of key, ligand-based, structural parameters on the mode of coordination. The synthesis and characterisation of the bis(diphenylphosphino )-ethylamine, Ph2PN(Et)PPh2, ligand and its subsequent reactions with various palladium precursors is described in Chapter 2. Reaction with the Pd(II) precursor, [PdCI2(PhCN)2], afforded the mononuclear complex cis-[PdCI2{ n2-Ph2PN(Et)PPh2}]1; when the same reaction was carried-out in the presence of the Pd(0) species [Pd2(dba)3] (dba = dibenzylideneacetone) the dinuclear ligand-bridged complex [Pd2C12 {u-Ph2PN(Et)PPh2}2] was formed. Reaction of 2 with I2 afforded 1, as well as the mononuclear di-iodo species cis-[PdI2 {n2-Ph2PN(Et)PPh2}] 3, and the mixed-halogeno complex [PdClI{n2-Ph2PN(Et)PPh2}] 4. Direct reaction of the ligand with [Pd2(dba)3] afforded, in the first instance, [Pd2{u-Ph2PN(Et)PPh2}3] 5, an extremely air-sensitive red compound, that readily reacted with oxygen in the solution to afford palladium metal and a yellow clathrate species that contained the oxidised ligand i.e., Ph2P(O)N(Et)P(O)PPh2. dba. H2O. Apart from 4, all compounds were characterised by means of elemental analysis, 1H and 3IP{1H} NMR spectroscopy and, in the case of 1, 2, 3 and Ph2P(O)N(Et)P(O)PPh2. dba. H2O, by means of single crystal X-ray structure determinations. The structures of the palladium complexes are, as expected, dominated by the requirement that the coordination geometry at the Pd atom is square-planar. In the case of the dinuclear ligand-bridged complex 2, this is achieved through formation of a Pd-Pd bond of length 2.600(1)A. Of particular interest is the crystal structure of the clathrate, which has the oxidised ligand and dba molecules stacked in alternating lines approximately parallel to the [c ]-axis of the unit cell. The synthesis and characterisation of the bis(2-pyridyl)phenylphosphine, PhP(py)2 ligand and its subsequent reaction with [PdCI2(PhCN)2] to afford the mononuclear complex cis-[PdCI2{n1-PhP(py)2}2] 6 is decribed in Chapter 3. The latter reacted with [Pd2(dba)3] to afford the dinuclear ligand-bridged species [Pd2CI2{u-PhP(py)2}2] 7. The 1H and 31P{1H} NMR spectral data, as well the results of single crystal X-ray structure determinations are reported for 6 and 7. The square-planar coordination at each palladium atom in 7 is achieved through the formation of a Pd-Pd bond of length 2.586(1)A. The synthesis and characterisation of the 2,5-(diphenylphosphino)thiophene, Ph2P(C4H2S)PPh2 ligand is described in Chapter 4. Reaction of the ligand with [PdCI2(PhCN)2] afforded the dinuclear ligand-bridged species [Pd2C14 {u-Ph2P(C4H2S)PPh2}2] 8. Characterisation of 8 was by means of elemental analysis, 1H and 31P{1H} NMR spectroscopy. Reaction of 8 with Ag+ in acetonitrile afforded a compound isolated as a yellow solid and formulated as [Pd2CI3(MeCN){u-Ph2P(C4H2S)PPh2}2] 9. Evidence for this formulation is based on the 31P{1H} NMR spectrum which shows two closely-spaced singlets, consistent with two sets of phosphorus atoms in different chemical environments, and too far separated (by 4 bonds) for magnetic coupling. Unfortunately, single crystals of these thienylphosphine ligand-bridged compounds could not be grown. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Compounds of the form RuO2(Y-py)2CI2 1 (py = pyridine, Y = H, 4-t-Bu, 3-CN, 4-CN, 2-Br, 3-Br, 4-Br, 4-Cl, 4-Me, 4-C(O)C6H5, 3-COOH, 4-COOH), RuO2ZCI2 2(Z = bipyridine, phenanthroline) and RuO2(OH)2(Y-py)2 3 (py = pyridine, Y = H, 4-CN, 4-t-Bu) were prepared and the effects of the various substituents on the properties of the compounds were investigated. The position of the v(Ru=O) bands of the complexes 1 correlate with the Hammett σ1 (or Taft σ*) and Pauling-type electronegativity values of the substituents on the pyridine ring. A comparative study of most of these complexes as both stoichiometric and catalytic oxidants for the oxidation of 1-hexanol to hexanal was carried out. The known dioxoruthenium(VI) compound [PPh4][RuO2(OCOCH3)CI2] (a) and a range of new compounds [PPh4][RuO2(OCOR)CI2] (R = CF3 b, C6H5 c, C6F5 d, C5H11 e) were synthesized and characterized. High synthetic yields were obtained for the fluorinated complexes b and d relative to their protonated equivalents a and c, possibly due to the varying charge distributions within such complexes. No clear trend in catalytic activity was noticed on varying the ligand on the ruthenium for the oxidation of 1-hexanol and 2-hexanol to hexanal and 2-hexanone respectively, with a range of co-oxidants. The complexes c and d were used very successfully in the catalytic oxidations of a variety of alcohols with the co-oxidants tetrabutylammonium periodate and 4-methylmorpholine N-oxide. The novel compounds [PPh4][RuO2(OCOC6H5)CI2 ] and [PPh4][RuO2(OCOC6F5)CI2] were supported on poly-4-vinylpyridine and used catalytically in oxidizing cyclohexanol to cyclohexanone, using 4-methylmorpholine N-oxide and tetrabutylammonium periodate as co-oxidants. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

The Fe- and Ru-promoted vanadium phosphorus oxide (VPO) catalysts were synthesized via the organic route in iso-butanol to form the VPO precursor, VOHPO4·0.5H2O. The resulting precursor was then activated in a stream of nitrogen to form an amorphous (VO)2P2O7, which crystallized after conditioning in the reactor in the presence of n-butane. The promoted catalysts were synthesized at 0.1%, 0.3% and 1% loading, pelletized and sieved to give a 300-600 μm pellet size. The catalysts were tested in a fixed-bed continuous flow micro-reactor and the products were analyzed by GC’s equipped with a flame ionization detector (FID) to monitor maleic anhydride and n-butane and a thermal conductivity detector (TCD) to monitor the carbon oxides. A range of characterization techniques were employed to determine the influence of the promoting elements on a VPO catalyst and to associate the composition of the catalysts obtained from such techniques with their performance. The characterization techniques used include X-ray diffraction (XRD), BET-surface area, ICP-OES, EDS, 31PNMR, TPR, redox titrations, ATR and SEM to determine the phase composition of the catalysts, the surface area of the promoted catalysts relative to the un-promoted VPO, elemental mole ratios, the reducibility of the catalysts, average vanadium oxidation state, determination of the anions present in the surface of the catalysts and the variations in the morphology of the catalysts, respectively. Optimization of the system involved variation of the GHSV, the reactor temperature and the promoter loading. (Activation of a 0.75% n-butane in air mixture was performed at an optimum temperature of 400oC while varying the gas hourly space velocity to establish a range of feed conversions and subsequently determine the activity of each catalyst with respect to n-butane conversion). The promoted catalysts modified the morphology of the catalysts as evidenced by the scanning electron microscopy and the X-ray diffraction patterns. Furthermore an improved conversion was obtained with these catalysts. However, only the 0.1% iron-promoted catalyst improved maleic anhydride yield leading to ca. 10% maleic anhydride yield increment. Yields of 46% and 55% were obtained at GHSVs of 2573 and 1450 per hour respectively and a temperature of 400oC. Electronic and structural modifications were encountered leading to an improved catalytic performance. The performance of this catalyst is associated with a vanadyl pyrophosphate phase (XRD), and a limited and controlled amount of V5+ species as illustrated in the TPR, and solid state 31P NMR data. Moreover, this modification can be considered both structural and electronic in nature as observed in the SEM images and FTIR spectra of this catalyst. Furthermore, this improved performance is possible at higher conversions 80 to 90% conversion. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Malaria remains one of the greatest problems facing developing nations, especially in sub-Saharan Africa. Part of the problem stems from increased resistance to current treatments hence there is a large drive to develop novel antimalarial compounds. Several chelating compounds, including 8-hydroxyquinoline (8-HQ), 1,10- phenanthroline (1,10-phen) and 2,2.6,2-terpyridine (terpy), have disputed activities (8-HQ and 1,10-phen) or are untested (terpy). Furthermore the mechanism(s) by which these ligands and/or their complexes with metal ions exhibit their toxic effect is unknown. In order to resolve these issues, a study of the antimalarial activities of the free ligands, the ligands complexed with metal ions (Au 3+, Cu 2+, Fe 3+, Pd 2+ and Pt 2+), and the ligands with free metals in solution were measured. The ligands, complexes and metals were also tested for their ability to inhibit β-haematin formation, the mode of action ascribed to the most widely used antimalarial, chloroquine. The background toxicity levels of the various metal ions (previously unreported) were also measured and are reported here. None of the ligands were found to have particularly high activity (all approximately 1μM). In general the metals in were found to have no beneficial effect on activity whether complexed or freely available in solution. None of the ligands were found to inhibit β-haematin formation. The complexes however, with the exception of those of Cu 2+, all inhibited β-haematin formation. Upon further investigation it was found that the each of the metal ions with the exception of Cu 2+ had an innate ability to inhibit β-haematin formation. Thus the mode of action of the ligands and the complexes is likely to be via different mechanisms. In an attempt to enhance the activities of the ligands they were modified by covalently linking them to nutrients essential to the malaria parasite (adenosine and pantothenic acid). These six novel compounds however, showed no improvement in action. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

Chiral crown ethers have recently been shown to be useful asymmetric catalysts in many carbon-carbon bond forming reactions. The design and synthesis of new chiral macrocycles and ligands for use in asymmetric catalysis is of great interest in the field of synthetic chemistry. Catalytic asymmetric Michael additions have been studied using chiral crown ethers as phase transfer catalysts. Many chiral crown ethers have been synthesised and tested in asymmetric catalysis but the design of these systems is still an area of much interest. The attempted synthesis of a new class of novel macrocycles such as 1 is described (chapter 2). The synthesis of a new class of chiral cage annulated macrocycles such as 2 is reported (chapter 3). The testing of these macrocycles as catalysts in the Michael addition of 2-nitropropane to chalcone was carried out with poor enantioselectivity being observed Recognition events in chemistry occur on a molecular scale that is difficult to monitor without the use of molecular devices. Photoinduced Electron Transfer (PET) systems have been the subject of much research over the past three decades. The attempted synthesis of the first chiral PET sensor 3 is described (chapter 4). / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2006.

The use of natural antioxidants to improve the oxidative stability of food lipids has received special attention because of the worldwide trend to avoid the use of synthetic food additives. A wide range of natural sources has been shown to contain antioxidant properties, these include plant extracts, herbs and spices, citrus fruits, oilseeds and legumes. Some antioxidants have been found to be fonned during the heat processing of foods, including the Maillard reaction products that are formed by the reaction of amino acids, peptides and proteins with reducing carbohydrates. A study was undertaken to investigate the antioxidant activity of Maillard reaction products fonned during extrusion of soyabeans. A preliminary oxidation study carried out to identify a suitable substrate revealed that sunflower oil stripped of antioxidants was a suitable substrate with a low induction period of 15 minutes via the Rancimat Method and 4.5 hours via the method of Ross and de Muelenaere. Methyllinoleate was found to be sensitive to oxidation, but not readily available and costly. Storage test of antioxidant stripped sunflower oil under various headspace conditions showed that the substrate stability was best at 4°C under nitrogen or vacuum. Under such conditions the product could be stored for a period of 136 days. Nitrogen was chosen as the most suitable for this exercise as it was not easy to remove all residual air from the samples by vacuum. Furthermore with nitrogen headspace residual 02 could be measured based on Ni02 ratio changes. Hexane solvent was found to be able to remove all lipids from soyabeans. Under the experimental conditions practised it was found that the induction periods for extruded and unextruded soya flour hexane extracted lipids were very similar. Addition of glucose or fructose to the extrusion mixture increased induction period of hexane extracted lipids by 37.5% and 1.5% respectively as measured by the Ross and de Muelenaere method and by 50% and 6.5% respectively as measured by the Rancimat Method. Available lysine of glucose containing extrudate was reduced by 69% while that of the fructose containing extrudate was reduced by 23%. Residual glucose and fructose analysis of extrudates showed that 66% of glucose was utilized in the formation of the Maillard reaction products while only 21% of fructose was utilized during extrusion processing. Comparison of induction periods of soya glucose and soya fructose extrudates to induction period of TBHQ antioxidants (200ppm) in antioxidant stripped sunflower oil gave antioxidant activity of 86ppm and 9ppm for soya glucose extrudates and soya fructose extrudates respectively. The observed antioxidant activity of Maillard reaction products could be utilized with success in different types of processed foods without the need for extensive testing as required for synthetic antioxidants but supplementation of lysine may be required to maintain nutritional balance. / Thesis (M.Sc.)-University of Natal, 1994.