Copper oxide supported on alumina (CuO/Al2O3), silica (CuO/SiO2) and chromia (CuO/Cr2O3) have been synthesized and characterized. These catalysts were characterized using XRD, SEM, TEM, ICP, BET surface area and pore volume, TPR, TPD, TGA-DSC and IR. The hydrogenation of octanal using these catalysts was investigated; however, the primary focus of the project was the influence of water on the reaction and the catalysts. The initial study using CuO/Al2O3 showed that the optimum operating conditions for subsequent catalytic testing was 160 °C and a hydrogen to aldehyde ratio of two. Under these conditions, a conversion of 99 % and selectivity to octanol of 97 % was achieved. Further catalytic testing, using CuO/Al2O3 and CuO/Cr2O3, was carried out by introducing water-spiked feed into the reaction system after steady state was reached using fresh feed. Based on literature, it was initially expected that the presence of water would cause catalyst poisoning and subsequently catalyst deactivation. However, contrary to the expectation, the presence of water did not influence the activity of these two catalysts. Furthermore, the selectivity to octanol increased to 98.5 % when CuO/Al2O3 was used for the reaction, whilst a minor change in the selectivity to octanol (0.5 %) was obtained when CuO/Cr2O3 was used. The interaction of the water with the surface hydroxyls on alumina is most likely the reason for the increase in the selectivity to octanol when using CuO/Al2O3. In contrast to the other two catalysts, the reaction over CuO/SiO2 showed a steady decrease in both the conversion of octanal and the selectivity to octanol with time-onstream when using fresh feed. After 55 hours on stream, the conversion reached 22 %, (from an initial 95 %) whilst the selectivity to octanol reached 89 % (from an initial 98 %). This decline in the conversion and selectivity to octanol was possibly due in part, to the low isoelectric point of silica, with mechanical failure being the major contributing factor to the catalyst’s deactivation. The decrease in the BET surface area and the presence of smaller particles in the SEM image, confirmed that mechanical failure occurred. Since steady state was not reached and deactivation occurred, the reaction over CuO/SiO2 was also carried out using water-spiked feed. The conversion of octanal was seen to gradually decrease to 73 % after 55 hours on stream, whilst the selectivity to octanol remained unchanged at 98 % for the duration of the reaction. This showed the beneficial effect of the presence of water by slowing down the decline in catalytic activity and maintaining the selectivity to octanol. The improved selectivity obtained in the presence of water was attributed to its interaction with the silica surface hydroxyls. Since octanal conversion continued to decrease, it indicated that mechanical failure was the primary cause in the loss of catalytic activity. The used catalysts were characterized using XRD, SEM, EDS composition scanning, TEM, BET surface area and pore volume, TGA-DSC and IR. The catalysts used for the reaction with the fresh feed and the water-spiked feed were characterized and compared. Except for the deactivation of CuO/SiO2, the characterization of these catalysts showed that the presence of water did not negatively impact the make-up of the catalyst. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2010.

This study was aimed at investigating the suitability of 2-alkyl/alkenylbenzo-1,3,2-diazaborolane compounds as potential nucleophilic coupling partners in the Suzuki-Miyaura cross-coupling reaction. A range of aryl bromides and iodides bearing electron-donating as well as electron-withdrawing substituents were reacted with 2-alkyl/alkenylbenzo-1,3,2-diazaborolane compounds under the influence of Pd(OAc)2/PCy3 combination. The cross coupling reaction afforded the desired products in yields ranging from 35% to 89% in less than 20 minutes. The catalytic system was found to be versatile and general tolerating a variety of functional groups including OMe, NO2, OH, COOMe and COMe2, thus demonstrating the suitability of 2-alkyl/alkenylbenzo-1,3,2-diazaborolane as coupling partners in the Suzuki-Miyaura cross-coupling methodology. The results from this study have been accepted for publication, full reference: (Sithebe, S., Hadebe, S. W., Robinson, R. S. Tetrahedron, 2011, 67, 4277.) Encouraged by the successful application of 2-alkyl/alkenylbenzo-1,3,2-diazaborolanes as coupling partners in the Suzuki-Miyaura (SM) cross-coupling reaction, we then extended our studies to investigate the synthesis and subsequent application of 2-arylbenzo-1,3,2-diazaborole analogues as potential coupling partners under the Suzuki-Miyaura cross-coupling reactions. The cyclocondensation of arylboronic acids with the corresponding 1,2-phenylenediamine afforded 2-arylbenzo-1,3,2-diazaboroles in yields ranging from 43% to 93%. The cross-coupling reaction of 2-arylbenzo-1,3,2-diazaboroles with the range of aryl bromides afforded the desired biaryl products in moderate to excellent yields ranging from 62% to 96%. Substrates bearing electron-withdrawing substituents were shown to be more reactive under these reaction conditions affording biphenyls in excellent isolated yields ranging from 83% to 96%. While our yields are comparable with the yields reported in literature, our reactions take only 10 minutes (!) compared to many hours of reflux as reported in the literature. This project was also aimed at investigating the spectroscopic characteristics of 2-arylbenzo-1,3,2-diazaborole compounds by acquiring and studying their absorption and emission spectra. The data obtained revealed the lack of significant v solvatochromism for all the compounds in the ground state which is indicative of the presence of low dipole moments. These values were confirmed computationally which showed low calculated dipole in a range 0.1379-2.2773 D. In the excited state, all chromophores are influenced by the polarity of the solvent used pointing to the presence of solvatochromism. The introduction of a donor group such as thioether (MeS) and the introduction of bromine atom, on the π-system, have proven beneficial for the emission maxima of the species investigated. The extension of π-conjugation length at the 2-position of these species and the methylation at the backbone of 1,3,2-benzodiazaborolyl group leads to bathochromic shifts of the emission maxima, which in turn lead to large Stokes shifts of up to 11000 cm-1. Alternatively, the formal insertion of the phenyl spacer between the naphthyl ring and the 1,3,2-benzodiazaborolyl group does not have any influence on the photophysical properties of these compounds. The HOMOs solvatochromism for all the compounds in the ground state which is indicative of the presence of low dipole moments. These values were confirmed computationally which showed low calculated dipole in a range 0.1379-2.2773 D. In the excited state, all chromophores are influenced by the polarity of the solvent used pointing to the presence of solvatochromism. The introduction of a donor group such as thioether (MeS) and the introduction of bromine atom, on the π-system, have proven beneficial for the emission maxima of the species investigated. The extension of π-conjugation length at the 2-position of these species and the methylation at the backbone of 1,3,2-benzodiazaborolyl group leads to bathochromic shifts of the emission maxima, which in turn lead to large Stokes shifts of up to 11000 cm-1. Alternatively, the formal insertion of the phenyl spacer between the naphthyl ring and the 1,3,2-benzodiazaborolyl group does not have any influence on the photophysical properties of these compounds. The HOMOs of all the chromophore are purely represented by the 1,3,2-benzodiazaborolyl group except for anthracenyl-functionalised benzo-1,3,2-diazaborolane compounds in which the HOMO are located on the π-system with no contribution of the vacant 2pz-orbital of the boron atom. The large Stokes shifts and significant solvatochromism displayed by these compounds are suggestive of the potential application in organic light emitting diodes (OLED) as emitters. The results from this study have been drafted for publication in Dalton Transition. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

The aim of this project was a broad one, namely to develop general methods for the preparation of nitrogen-containing heterocycles. This topic also encompasses the preparation of precursors to heterocycles with the goal of obtaining compounds that can undergo various transformations to give different cyclic products (general synthetic precursors). Workers in our group have previously reported the preparation of indolizinones from N-propargyl enaminones. Immediate goals were to elucidate the mechanism of this transformation, optimise its yields and explore its generality. Initial work revealed a possible reaction intermediate in the form of isomeric N-allenyl enaminones. These compounds can be easily prepared from N-propargyl enaminones using potassium tertbutoxide. Although parallels between the two reactions were noted, the presence of N-allenyls as reaction intermediates was not substantiated. In spite of this, N-allenyl enaminones were considered to be potentially valuable compounds in their own right and their chemistry was briefly explored. It was shown that they undergo hydroboration smoothly yielding only one hydroboration product. This was observed using dynamic iiB NMR spectroscopy. Subsequent oxidation gave interesting results and these are discussed further. At this stage it was considered important to prepare piperidine and acyclic analogues of the N-allenyl enaminones already synthesised. Both preparations proved problematic and were ultimately abandoned. Although these attempts were not fruitful, a number of interesting observations were made en route and contribute to the discussion. Whilst attempting to prepare acyclic analogues it was found that when a mixture of a secondary enaminone and propargyl bromide was treated with silver nitrate functionalised pyrroles were formed. This method of pyrrole formation, although low yielding (~25%), was both novel and intriguing. As pyrroles are important heterocycles and common synthetic targets, further work was carried out to elucidate the mechanism in operation during this conversion. A thorough investigation led to a proposed mechanism involving silver-mediated hydro amination followed by an intramolecular nucleophilic substitution. This proposed mechanism is discussed further. Carrying out the reaction over two steps was found to improve the procedure. Carbon-carbon bond formation prior to an intramolecular silver-catalysed hydroamination provides superior overall yields. Intramolecular hydroamination can be carried out at room temperature or using microwave irradiation. Employing microwave irradiation reduces reaction times from sixteen hours to sixty seconds without any decrease in yields. This process was extended to bicyclic systems, namely N-bridgehead pyrroles. The preparation of the necessary cyclic precursors via a protection-deprotection strategy is described. N-Bridgehead pyrroles provide the framework for pyrrolizidine, indolizidine and lehmizidine alkaloids and general synthetic protocols toward the synthesis of such alkaloids is proposed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Benzimidazole and its derivatives have attracted many organic chemists due to their interesting biological activities. These include activities against viruses such as, HIV, RNA, herpes (HSV-1), influenza, and cytomegalovirus (HCMV); antimicrobial and antitumor activities. Even though a lot of research has been conducted on the synthesis of benzimidazoles, factors such as, drug resistance present a need for synthesis of more structural analogues of these compounds. In chapter three, the synthesis of 2-aryl-1Hbenzimidazoles (46a-c) and 2-aryl-1-arylmethyl-1H-benzimidazoles (49a-d) is described. The yields for these products ranged from 44-79 % and 62-72 %, respectively. The synthesis of novel bisbenzimidazole derivatives is described in chapter four. Direct condensation of 3,3'-diaminobenzidine (1 mmol) with 2-thiophenecarboxyaldehyde (2 mmol) afforded 2, 2’-di-2-thienyl-5,5-Bi-1H-benzimidazole (52) in 65 % yield. Except in the case of 2-furancarboxyaldehyde, the acid catalyzed condensation of 3,3'- diaminobenzidine (1 equivalent) and heteroaromatic aldehydes (4 equivalents) gave novel bisbenzimidazoles where the aldehyde added three times to 3,3'-diaminobenzidine. The four times addition product, 1,2-di-2-furanylmethyl-2,2-di-2-furanyl benzimidazole (53) was obtained in 53 % yield. On the other hand, the three times addition product, 1,2-di-2- pyrrolylmethyl-2,2-di-2-pyrrolyl (54); 1,2-di-2-thienylmethyl-2,2-di-2-thienyl (55); and 1,2-di-2-pyridylmethyl-2,2-di-2-pyridyl benzimidazoles (56) were obtained in 85, 12 and 10 %, respectively. Full characterization of bisbenzimidazoles (54-56) was achieved by 1H, 13C NMR and LCMS spectra. Although benzimidazoles have been proven to be active against various cancers, their use as ligands for platinum (II) has been reported to enhance this activity. Three new benzimidazole Pt (II) complexes were synthesized. N, N, N-bound Pt (II) complexes of 2- quinolyl-1-quinolylmethyl-1H-benzimidazole (60) and 2-pyridyl-1-pyridylmethyl-1Hbenzimidazole (63) were obtained in excellent yields of 82 and 72 %, respectively. S, Nbound Pt (II) complex of 2-thienyl-1-thienylmethyl-1H-benzimidazole (64) was isolated in 63 % yield. From 195Pt NMR spectra analysis, it was concluded that the method reported by Morgan and Burstall is more efficient for the synthesis of these complexes. In addition to 195Pt NMR, platination was also confirmed using 1H and 13C NMR spectra. / Thesis (PhD.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Chapter One serves as an introduction to the photophysical properties of square-planar 2,2':6',2/1-terpyridyl and 6-phenyl-2,2'-bipyridylligand complexes of platinum(II). A brief description is provided of the absorption and emission spectra of each complex, the latter generally both in solution and the solid state. The assignments made to the absorption and emission bands are reported, together with the lifetimes ofthe emitting states where these have been measured. The relationship between the molecular and/or crystal structure of the complex and its photophysical properties is discussed. Given this background, the overall aims of the work in this dissertation are presented. In Chapter Two the synthesis and characterisation of nine novelligands are described. These are 4'-(O-naphthyl)-2,2':6',2/1-terpyridine (4'-fJNp-terpy), 4'-(meta-biphenyl)-2,2':6',2/1-terpyridine (4'-mBiph-terpy), 4'-(para-biphenyl)-2,2':6',2"-terpyridine (4'-pBiph-terpy), 4-(fJnaphthyl)- 6-pheny1-2,2'-bipyridine (H4-fJNp-phbipy), 4-(para-biphenyl)-6-pheny1-2,2'bipyridine (H4-pBiph-phbipy), 4-phenyl-6-(2'-pyrazinyl)-2,2'-bipyridine (4-Ph-pzbipy), 4(ortho-CH3-phenyl)-6-(2'-pyrazinyl)-2,2'-bipyridine (4-oMePh-pzbipy), 4-(ortho-CF3-phenyl)6-pyrazinyl-2,2'-bipyridine (4-oCF3Ph-pzbipy) and 4-phenyl-2,6-bis(2'-pyrazinyl)-pyridine (4-Ph-pybipz). In Chapter Three the synthesis, characterisation and photophysical properties of platinum(II) complexes ofthe ligands 4'-jlNp-terpy, 4'-mBiph-terpy and 4'-pBiph-terpy are described. The complexes are salts prepared of the following composition: [Pt(4'-jlNp-terpy)CI]SbF6 (1), [Pt(4'-jlNp-terpy)Cl]BF4 (~), [Pt(4'-jlNp-terpy)Cl]CF3S03 (J), [Pt(4'-mBiph-terpy)Cl]SbF6 (1), [Pt(4'-mBiph-terpy)Cl]BF4 (~), [Pt(4'-mBiph-terpy)Cl]CF3S03(~), [Pt(4'-pBiph-terpy)CI]SbF6 (1), [Pt(4'-pBiph-terpy)Cl]BF4 (~) and [Pt(4'-pBiph-terpy)Cl]CF3S03 (2). Each ligand is characterised by a substituent in the 4'-position that has been designed to permit free rotation of that substituent about the interannular bond to the terpyridyl fragment. The rotational freedom allows the 4'-substituent to adopt an orientation nearly coplanar with that of the terpyridyl fragment. As a result ofthe extensive n-conjugation, there is a strong ligand-centred influence in their excited state emission spectra. Evidence is also presented for 3MLCT (metal 111 to ligand charge transfer) character in the emitting state, in particular that the emission is quenched in coordinating solvents. In addition, an 3ILCT (intraligand charge transfer) contribution has been proposed to account for the exceptionally long lifetimes measured in fluid solution for [Pt(4'-j3Np-terpy)C!t (12 jJs), [Pt(4'-pBiph-terpy)Cq+ (4 jJs) and [Pt(4'-aNpterpy) C!t (17 jJs). We conclude that large easily ionisable substituents in the 4'-position of the terpyridyl moiety ensure long lifetimes in fluid solution for platinum(II) complexes of these ligands. The same assignments apply to the solid state spectra of the yellow or pale orange salts that exhibit monomeric emission in the solid state, these being: [Pt(4'-j3Np-terpy)CI]SbFu (l), [Pt(4'-j3Np-terpy)CI]BF4 (I), [Pt(4'-j3Np-terpy)CI]CF3S03(J.), [Pt(4'-pBiph-terpy)CI]SbFu (1) and [Pt(4'-pBiph-terpy)CI]BF4 (~). In the solid state two additional types of solid state emission have been identified in cases where intermolecular interactions are present. The first type is typical of red or dark orange salts viz., [Pt(4'-mBiph-terpy)Cl]SbFu(1), [Pt(4'-pBiphterpy) Cl]BF4 (red form) (~) and [Pt(4'-pBiph-terpy)Cl]CF3S03 (.2). All three salts exhibit MMLCT (metal-metal to ligand charge transfer) emission brought about by close intermolecular Pt···Pt interactions in the solid. Finally, the three orange compounds [Pt(4'mBiph-terpy)Cl]SbFu.CH3CN (4a), [Pt(4'-mBiph-terpy)Cl]BF4 (~) and [Pt(4'-pBiphterpy) Cl]CF3S03(.2) exhibit simultaneous emission from IL (intraligand) and MMLCT states that are similar in energy. In the case of [Pt(4'-mBiph-terpy)Cl]SbF6.CH3CN (4a) the assigmnent ofMMLCT emission is supported by a X-ray crystal structure determination that shows the cations interacting in dimeric pairs which have a platinum-platinum separation of 3.356(2) A. In Chapter Four the synthesis, characterisation and photophysical properties of the neutral complexes [Pt(4-j3Np-phbipy)Cl] (10) and [Pt(4-pBiph-phbipy)Cl] (11) are described. The ligands, 4-j3Np-phbipy and 4-pBiph-phbipy are closely related to 4'-j3Np-terpy and 4'-pBiphterpy, the only difference being that the terpyridyl fragment is replaced by a phenyl-bipyridyl moiety that binds to the platinum via a deprotonated carbon atom in the ortho-position of the phenyl ring. The stronger a-donor strength of the anionic carbon atom is shown to result in: (i) a marked shift to the red in the MLCT absorption bands for the two complexes and (ii) a significant lowering of the energy ofthe emitting state, as compared to that observed for the cationic terpyridylligand derivatives. The assignment of the emission as 3ILPMLCTin origin remains the same, however, both in solution and in the solid state. In Chapter Five we report the synthesis, characterisation and photophysical properties of a series of platinum(II) complexes of the ligands 4-Ph-pzbipy, 4-oMePh-pzbipy, 4-oCFJPhpzbipy and 4-Ph-pybipz viz., [Pt(4-Ph-pzbipy)CI]BF4 (12), [Pt(4-oMePh-pzbipy)CI]SbF6 (14), [Pt(4-oMePh-pzbipy)CI]BF4 (15), [Pt(4-oMePh-pzbipy)CI]CFJSOJ (16), [Pt(4-oCFJPhpzbipy) CI]SbF6 (17), [Pt(4-oCFJPh-pzbipy)CI]BF4 (18) and [Pt(4-oCFJPh-pzbipy)CI]CFJSOJ (19). These ligands coordinate to platinum via a binding domain analogous to the terpyridyl fragment except that one (or both in the case of 4-Ph-pybipz) of the outer pyridine rings is replaced with a pyrazine ring. The ligands 4-oMePh-pzbipy and 4-oCFJPh-pzbipy are distinguished from 4-Ph-pzbipy by the presence of bulky methyl and trifluoromethyl substituents, respectively, in the ortho position of the peripheral phenyl ring. Monomer emission measured in room temperature fluid solution in a 77 K rigid glass for the three luminophores viz. [Pt(4-Ph-pzbipy)CIt, [Pt(4-oMePh-pzbipy)CIt and [Pt(4-oCFJPhpzbipy) Clr derives from an excited state of JILPMLCT mixed orbital parentage. Their emission energies are stabilised compared to their terpyridyl analogues but emission lifetimes are essentially the same. Solid state emission spectra have been recorded for salts ofthe [Pt(4oMePh- pzbipy)CW and [Pt(4-oCFJPh-pzbipy)CW cations. In every case emission is derived from an excited state brought about by intermolecular interactions, either in the form of excimeric or of MMLCT emission. In general orange compounds ([Pt(4-oCFJPhpzbipy) CI]SbF6 (orangeform ) (17) and [Pt(4-oCFJPh-pzbipy)CI]BF4 (18)} displayexcimeric emission and dark red compounds {[Pt(4-oMePh-pzbipy)CI]SbF6 (14), [Pt(4-oMePhpzbipy) CI]BF4 (15), [Pt(4-oMePh-pzbipy)CI]CFJSOJ(16), [Pt(4-oCFJPh-pzbipy)CI]SbF6 (red form) (17) and [Pt(4-oCFJPh-pzbipy)CI]CFJSOJ (19)} display emission from a MMLCT excited state. The [Pt(4-oCFJPh-pzbipy)CI]SbF6 (17) salt displays polymorphism, existing in two formS, one red and the other orange. In all cases the lower energy of the n-acceptor orbitals of the pyrazinyl-bipyridyl moiety causes emission to be at lower energies compared to that recorded for closely related terpyridyl analogues. Finally, attempts to coordinate the bis-pyrazinylligand, 4-Ph-pybipz, to platinum to form [Pt(4-Ph-pybipz)CI]SbF6 (13) were unsuccessful. / Thesis (PhD.)-University of Natal, Pietermaritzburg, 2002. / National Research Foundation. De Beers Industrial Diamond Division.

This study comprises the preparation and characterisation of various novel tertiary monoand polyphosphines as well as their gold(I) complexes. The possible modes of coordination of mono-, bi- and tridentate phosphine ligands to gold(I) are summarised in Chapter One, thus serving as an introduction to coordination behaviour of the new ligands to gold(I). The synthesis and characterisation of twelve novel tertiary mono- and polyphosphines as well as the three previously known thienylphosphines, diphenyl(2-thienyl)phosphine (PS), phenyldi(2-thienyl)phosphine (PDS) and tris(2-thienyl)phosphine (PTS), are reported in Chapter Two. There are four phosphines derived from a monothiophene unit i.e., diphenyl(5-bromo-2-thienyl )phosphine (PSBr), 2,5-bis(diphenylphosphino)thiophene (PSP), phenylbis[(5-diphenylphosphino)-2-thienyl]phosphine (PDSP) and tris[(5-diphenylphosphino)- 2-thienyl]phosphine (PTSP); two from a 2,2'-bithiophene unit i.e.. diphenyl[5( 2,2'-bithienyl)]phosphine (PSS) and 5,5'-bis(diphenylphosphino )-2,2'-bithiophene (PSSP); h hi fr ') ')'. two P osp mes om a _,_ .)-,,_')"-terthiiophene um.t t..e., diipheny1[)--('_)._')'..)-,._')"-terthiieny1)]- phosphine (PSSS) and 5,5"-bis(diphenylphosphino)-2,2':5',2"-terthiophene (PSSSP); three phosphines from a 2-(2'-thienyl)pyridine unit i.e., diphenyl[5-(2'-pyridyl)-2-thienyl]phosphine (PSN), diphenyl[6-(2'-thienyl)-2-pyridyl]phosphine (PNS) and diphenyl[5-(2'{ 6'-diphenylphosphino}pyridyl)-2-thienyl]phosphine (PSNP); and one phosphine from a 2,6-bis(2'-thienyl)pyridine unit i.e., 2,6-bis[(5'-diphenylphosphino )-2'-thienyl]pyridine (PSNSP). A combination of IH, l3C and 31p NMR spectroscopy as well as mass spectrometry and microanalysis is employed to establish the structures for all the compounds, while in three cases (for the ligands PSSP. PSNP and PSNSP) the structural assignment is confirmed by X-ray crystallography. The synthetic strategies used for the preparation of the phosphine ligands vary widely from a traditional reaction between a metallated thiophene and a chlorophosphine on one hand, to a Ni-catalysed coupling reaction involving phosphine-substituted heterocycles on the other. the choice depending not only on the parent heterocyclic molecule. but also on the number of phosphorus atoms present. A new synthetic methodology leading to a potentially water-soluble diphosphine ligand is also explored. Although the target compound itself is not isolated, the preparation of its precursor, 5.5'-bis(phenylphosphino )- Xl 2,2'-bithiophene (HPSSPH), represents the first example of the synthesis of a secondary phosphine containing a thiophene moiety. In Chapter Three the reactions of the mono- and diphosphine ligands PS, PDS, PTS, PSBr, PSS, PSSS.- PSN.. PNS.- PSP.' PSSP.. PSNP.. PSSSP and PSNSP with the. gold(I) precursors (such as HAuCI4, reduced in situ with thiodiglycoL and [Au{MeCNh]SbF6) are studied. The structures of the products are elucidated by means of 'n and 31 p NMR and IR spectroscopy as well as X-ray crystallography in the case of [CIAuPSS], [CIAuPNS], [CIAu(PDS)2], [CIAu(PS)3] and [Au2(~-PSNh](SbF 6)2. Neutral complexes containing twocoordinate gold(I) are obtained for all the ligands, having general formulae [ClAuP] and [CIAu(~-PP)AuCI] , where P and PP represent a mono- and a diphosphine respectively. Isolation of neutral complexes with three-coordinate gold(I) proved more difficult and is only achieved for the complexes [CIAuP2] (P = PS, PDS, PTS and PSN) and [CIAu(~PP)] n (PP = PSP and PSSSP). A 31 p NMR study of the behaviour of complexes in solution shows the complexes with three-coordinate gold to be very labile with respect to dissociation of the third ligand. The complex [CIAu(PS)3], where gold(I) exhibits a coordination number intermediate between 3 and 4 in the solid state (as shown by the Xray crystallographic analysis), is serendipitously obtained from a reaction of [CIAu(PPh3)] and PS in a I :1 molar ratio. Both mono- and dinuclear complexes with two-coordinate gold(I) are formed when the monophosphines PSN and PNS are reacted with suitable precursors (viz. [CIAuPNS] and [Au{MeCNh]SbF6). The mononuclear complexes are of formula [Au(r{Ph]SbF6, as confirmed by IH and 3lp NMR and IR spectroscopy. In the case of the dinuclear complexes. [AU2(~-PhJX2 (P = PSN. X = SbF6: P = PNS. X = PF6), bridging is achieved via the phosphorus atom and nitrogen atom of the pyridine ring 1n both ligands. This coordination mode is consistent with the IH and 31 p NMR data for both complexes. and it is also confirmed by an X-ray structure determination of the former complex. The diphosphine ligands PSSP, PSNP and PSNSP tend to produce insoluble polymeric products when reacted with cationic gold(I) precursors. while the diphosphines PSP and PSSSP allow discrete species (e.g. [Au{r!'-PSSSP}z]PF6 and [Au2 {~-PSP hHPF6 }z ) to be isolated under similar conditions. None of the gold(I) complexes synthesised in this work displays any evidence of the thiophene ring being one way or the other coordinated to the metal, XII Chapter Three concludes with a short description of the luminescence properties of a selection of gold(I)-phosphine complexes both in solution and in the solid state. Our results confirm the previously established trend that complexes containing three-coordinate gold(I) tend to luminesce. They also show, for the first time, that a dinuclear complex with no metal-metal interaction, and where each gold atom is coordinated to one phosphorus and one nitrogen donor atom i.e., [Au2(Il-PSN)2](SbF6L exhibits luminescent properties. The results of the cytotoxic testing of a number of mono- and diphosphines (PS, PDS, PTS, PSS, PSSS, PSSP, PSSSP, PSNSP and dppe) as well as of some heterocyclic compounds and the gold(I ) complexes [CIAuPSS] and (CIAu(Il-PP)AuCI] (PP = PSSP and dppe) against two cell lines are presented in Chapter Four. The complex [CIAuPSS] shows great potency against the HepG2 (liver cancer) cell line, far exceeding that of the known cytotoxic agent, [Cl.Autu-dppej.Auf'l]. For the other cell line. A549 (lung cancer), the cytotoxicity measurements are compared for 'in the dark' and under DVA light conditions. The results show that application of DVA light generally increases the cytotoxic properties of the compounds tested. Although there appears to be a link between the phototoxic properties of a compound and its photosensitising ability (a photophysical property of thienylphosphine ligands and their gold(I ) complexes, reported at the beginning of Chapter Four) , it is not yet possible to establish a quantitative correlation between the two. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000

The excess molar volumes VEm and the excess molar enthalpies HEm have been determined for several binary systems at 298.15 K using an Anton Paar Digital Densitometer and a 2277 Thermal Activity Monitor, respectively. VEm and HEm have been determined over the whole composition range for three types of binary mixtures involving hydrogen bonded interactions. The three types are: (i) a short chain alkanol (methanol, ethanol, 1-propanol, 2-propanol) or (ii) a symmetrical secondary amine (di-n-ethylamine, di-n-propylamine) or (iii) 1-alkyne (l-hexyne, 1-heptyne, l-octyne) with a branched chain ether (diisopropyl ether, 1,1-dimethylethyl methyl ether, 1,1dimethylpropyl methyl ether) and a cyclic ether (tetrahydrofuran, tetrahydropyran, 1,4dioxane). For mixtures of (an alkanol + a branched chain ether or a cyclic ether) the results are explained in terms of the strong self association exhibited by the alkanol and the cross association of the OH:::::O specific interaction. In particular for mixtures of (an alkanol + a cyclic ether) the results show trends relating to the size of the cycloether ring and the number of carbon atoms in the alkanol molecule. For mixtures of a secondary amine + a branched chain ether or a cyclic ether the experimental results have been explained on the basis of the strong molecular interactions (NH·····O) between the weakly self associating secondary amine and the ether oxygen. For binary mixtures of 1-alkyne + a branched chain ether the results indicate a dominance of the π....π interaction over either the dissociation effects of the 1-alkyne (π..... π interactions) or the breakdown of the branched chain ether molecules self association. Thermophysical property data, density p, cubic expansion coefficient ex and isothermal compressibility KT have also been determined for several aliphatic ethers from 288.15 K to 328.15 K at pressures ranging from 0.1 to 8 MPa. The molar volumes derived from the densities have been fitted to a polynomial as a function of temperature and pressure and the second order thermodynamic functions, the cubic expansion coefficient ex and the isothermal compressibility KT determined. For all the ethers, the cubic expansion coefficients decrease with an increase in temperature or pressure while the isothermal compressibilities increase with an increase in temperature or pressure over the temperature and pressure ranges investigated. This work was carried out in the Thermodynamics laboratory of the Indian Institute of Technology in India. This data was required so that the experimental VEm and HEm data could be analyzed using modern theories of liquid mixtures. The VEm and HEm data presented here has been subjected to the following theoretical analysis: (i)The Extended Real Associated Solution (ERAS) model, (ii)The Modified Universal Functional Activity Coefficient (UNIFAC) group contribution model and (iii) The simple Flory and the Prigogine Flory Patterson theory (PFP). All the theories exhibited partial success when applied to the systems investigated here. Excess molar volumes and excess molar enthalpies, VEm and HEm have also been determined over the whole composition range for binary mixtures involving symmetrical (a straight chain ether or ketone + a pseudo straight chain ether or a pseudo straight chain ketone) to test the applicability of the congruency theory. Not all of the mixtures satisfied the null test of the congruency principle. / Thesis (Ph.D.)-University of Natal, 1996.

Members of the Annonaceae and Meliaceae, two plant families which are distributed throughout the world, have been studied during the course of this work. The research is an account of the compounds isolated from six members of the Meliaceae (Australian, Indian and South African) and one from the Annonaceae (South African). These families have attracted special attention of scientists world-wide because of the compounds these plants produce and their medicinal applications. Extracts from these species are known to be widely used in traditional medicine and previous studies have demonstrated their anticancer, anti-microbial and other pharmacological activities. Limonoids and protolimonoids were isolated from the Indian Meliaceae specIes, Aphanamixis polystacha and from the South African Meliaceae species Turraea obtusifolia. Extractives from the seeds of Aphanamixis polystacha yielded seven limonoids (2-A to 2-G) from the hexane extract, while the methanol extract only yielded sucrose (2-H). Three of the limonoids (2-B, 2-E and 2-F) were novel and the stereochemistry of polystachin, compound (2-A), was revised. Extractives from Turraea obtusifolia yielded two triterpenoids (3-A and 3-B) and a limonoid (3-C) from the hexane extract of the seed. Several triterpenoids and a benzofuran compound were isolated from the Australian Meliaceae species, Dysoxylum pettigrewianum, Dysoxylum muelleri and Aglaia sapindina. Extractives from Dysoxylum pettigrewianum, yielded three triterpenoids (4-A to 4-C) from the hexane extract of the bark. Two of these triterpenoids (4-Band 4-C) were novel. Extractives from Dysoxylum muelleri yielded two triterpenoids (4-D and 4E) from the methylene chloride extract of the wood. Extractives from Aglaia sapindina yielded a benzofuran compound (4-F) from the hexane extract of the wood. This resulted in the revision of the structure of ferrugin (4-56). A flavonoid (5-A) was isolated from the aqueous extract of the seed of the South African Meliaceae Trichilia dregeana. A polyoxygenated cyclohexane epoxide (6-A) was isolated from the root and leaves of the Annonaceae species, Monanthotaxis caffia. The research undertaken involved the collection, extraction, isolation, purification and structural elucidation of these compounds by infrared, mass and nuclear magnetic resonance spectroscopic techniques. / Thesis (Ph.D.)-University of Natal, 1997.

The aim of this work was to extend the theory of Everett and Cruickshank, for the determination of activity coefficients at infinite dilution, Y 13 (where 1 refers to the solute and 3 to the solvent), to accommodate solvents of moderate volatility, using the gas liquid chromatography (GLC) method. A novel data treatment procedure is introduced to account for the loss of solvent off the column, during the experiment. The method also allows us to determine the vapour pressure of the solvent. No auxiliary equipment is required, and the method does not employ the use of a presaturator. Further, the effect of a polar involatile solute is examined using various types of solutes. The activity coefficient was found to be independent of column packing and flowrate. Considering the volatile solvent, the systems investigated by the GLC method were straight chain hydrocarbons, (n-pentane, n-hexane and n-heptane), cyclic hydrocarbons (cyclopentane, and cyclohexane) and an aromatic compound, benzene. The systems were investigated at 2 temperatures, 280.15 K and 298.15 K. The results indicate a clear dependence of the activity coefficient on temperature. For the polar nonvolatile solvent, sulfolane (tetrahydrothiophene, 1,1 dioxane) was used. The systems studied were sulfolane + n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, benzene, tetrahydrofuran, and tetrahydropyran. The systems were studied at one temperature, 303.15 K, due to the low melting point of sulfolane i.e. 301.60 K. Part of this study into the thermodynamics of solutions'\vas conducted at the Technical University of Warsaw, where the equilibria of sulfolane was studied using· two techniques, a dynamic solid-liquid equilibrium method (SLE), and an ebulliometriGI vapor-liquid method (VLE) . The main purpose of this was to apply solution theories to this data in order to predict the.activity coefficient at infinite dilution for the sulfolane mixtures. The systems measured using solid liquid equilibrium are sulfolane + tetrahydrofuran, or, 1,4-dioxane, or, I-heptyne, or, 1, 1, l,-trichloroethane, or, benzene, and cyclohexane. The results of these measurements were then described using various solution theories, and· new interaction parameters obtained. The vapour liquid equilibrium systems measured were sulfolane + I-heptyne, or, tetrahyrdofuran, or, 1,1, I-trichloroethane, and tetrachloromethane. Here as in SLE the results were described using solution theories. The results of both the VLE and SLE measurements were used in a multiple optimization procedure to produce new parameters for the interaction of sulfolane with various groups, using two group contribution method, DISQUAC and modified UNIFAC. The predicted activity coefficients compare well with the measured values using GLC. / Thesis (Ph.D.)-University of Natal, 1995.

Despite over 50 centuries of living with the disease, tuberculosis (TB) still remains one of the oldest and deadliest diseases known to man and is gradually becoming a serious threat to the human race. According to the 2009 Global tuberculosis control report of the World Health Organisation (WHO), it is estimated that about 9.4 million incident cases of TB occurred globally. Of these cases an estimated 1.4 million were HIV positive of which 78 % were in the African region while 13 % are located in the South-East Asia Region. An estimate of 1.3 million deaths was reportedly caused by TB among HIV negative people. South Africa has the highest percentage of HIV patients living with tuberculosis. The design, synthesis and evaluation of novel polycyclic ‘cage’ amines for their pharmaceutical profiles are presented in this thesis. In this project a total of 12 novel intermediates and 31 novel products were synthesised. A thorough NMR elucidation of the various structures was also pursued. This study was motivated by the reported discovery of SQ109 by Sequella. SQ109 (N-Geranyl- N’-(2-adamantyl)ethane-1,2-diamine) shares the same 1,2 ethylenediamine pharmacophore with ethambutol (EMB), a commercial TB-drug. SQ109 also possess remarkable activity against MDR-TB which includes the EMB resistant strain suggesting that SQ109 is a new anti-TB drug and not an EMB analogue. SQ109 comprises of a polycyclic adamantane moiety, an isoprenyl moiety and a diamine. This study had three main aims, namely (a) the design and synthesis of novel polycyclic ‘cage’ amines derivatives; the polycyclic ‘cage’ moieties investigated in this study includes adamantane, trishomocubane, oxa-pentacycloundecane, aza-pentacycloundecane, pentacyclodecane and pentacycloundecane, (b) structural elucidation (using 2D NMR techniques) of synthesized novel polycyclic ‘cage’ amine derivatives (c) the anti-mycobacterial screening of novel polycyclic ‘cage’ amines derivatives against H37Rv, MDR (multi-drug resistant) and XDR (extensively-drug resistant) strains of Mycobacteria tuberculosis and (d) the anti-bacterial and anti-fungal screening of selected novel polycyclic ‘cage’ amine derivatives. Furthermore, the design, synthesis and NMR elucidation of a family of similar novel PCU diamine ligands are also reported herein. The aim of these ligands is to complex and transport copper ions to the sites of inflammation caused by arthritus. The known pharmaceutical properties of polycyclic ‘cage’ compounds such as their ability to cross membranes due to improved drug lipophilicity makes them suitable candidates for such a study. This project stems from a logic collaboration between UKZN, UCT (University of Cape Town) and CPUT (Cape Peninsula University of Technology) to test some of these cage diamines for activity against arthritus. Experimental work in this aspect is performed by the group of Prof. Graham E. Jackson (UCT) and Dr. Sebusi Odisitse (UPUT). / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.