Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The partial double bond character of the carbon-nitrogen bond of the (S)C-NRR’ moiety results in unsymmetrical dialkyl-substituted N-alkyl-N-alkyl(aryl)-N’-acylthioureas, R”C(O)NHC(S)NRR’ (HL) displaying E,Z configurational isomerism in solution. The isomerism manifests itself by the duplication of resonances of the N-alkyl groups in the 1H and 13C NMR spectra. In one class of these ligands where R and R’ groups are non-equivalent alkyl groups the isomerism is easily observable at 298 K in chloroform. In the other class where R’ is still an alkyl group and R is a para-substituted phenyl group the isomerism is only observable at much lower temperatures due to a lower barrier to rotation around the (S)C-N(alkyl)(para-X-Ph) bond (X = O-CH3, H and NO2). The electron-withdrawing nature of the nitro group in N-methyl-N-(4-nitro-phenyl)-N’-2,2-dimethylpropanoylthiourea, HL3A and N-pentyl-N- (4-nitro-phenyl)-N’-2,2-dimethylpropanoylthiourea, HL3D result in the E,Z isomerism of these ligands not observable even at 198 K in dichloromethane. The distribution of E and Z isomers of the unbound ligands vary depending on these R and R’ groups. Several E isomers of these ligands have been isolated and structurally characterised and the (S)C-NRR’ bond falls in the range [1.343(3) – 1.329(3) Å] which shorter than the average C-N single bond of 1.472(5) Å. The E,Z configurational isomerism in the unbound ligands is passed on to the Pt(II) chelates derived from these ligands. The presence of cis-[Pt(ZZ-L-S,O)2], cis-[Pt(EZ-L-S,O)2] and cis-[Pt(EE-L-S,O)2] is readily observable by means of 195Pt NMR spectroscopy which shows three well resolved resonances, and this can be confirmed by 1H and 13C NMR spectra of these complexes. The 195Pt nuclei are spatially linked to the 13C nuclei, four bonds away resulting in 4J(195Pt-13C) couplings with N-CH2- or N-CH3 carbons in a W pathway. The 195Pt NMR spectra are also linked to N-CH2- or N-CH3 proton resonances by means of the ZZ, EZ and EE isomer distributions. Assignment of these configurational isomers was then achieved by means of a combination of low magnetic field 13C NMR spectra and high-resolution gHSQC (1H/13C) NMR experiments. 1H NMR rotational dynamics study showed that the barrier to rotation, ΔG≠, around the (S)C-N(Me)(para-X-Ph) bond in cis-bis(N-methyl-N-(4-methoxy-phenyl)-N’-2,2-dimethylpropanoylthioureato)platinum(II), cis-[Pt(L1AS, O)2]; cis-bis(N-methyl-N-phenyl-N’-2,2-dimethylpropanoylthioureato)platinum(II), cis-[Pt(L2A-S,O)2] and cisbis( N-methyl-N-(4-nitro-phenyl)-N’-2,2-dimethylpropanoylthioureato)platinum(II), cis-[Pt(L3A-S,O)2] complexes was observed to follow the order: (electron-withdrawing group) NO2 < H < (electron-donating group) O-CH3. The ZZ isomer was observed to be favoured over the EZ and EE isomers in this order of the para-substituent on the Nphenyl group. The 1H dynamic NMR trends about the barrier to rotation, ΔG≠, around the (S)C-N(Me)(para-X-Ph) bond were also complemented by DFT linear transit calculations. The isomer distributions were also influenced by solvent polarity and the temperature at which the distributions are determined apart from the electronic influence of the para-substituent of the N-phenyl group. The ZZ, EZ and EE isomers of complexes derived from N-alkyl-N-(para-X-Ph)-N’-acylthioureas with varying Nalkyl substituent (methyl, isopropyl, cyclohexyl and n-pentyl) were determined from the 195Pt NMR spectra which were measured under identical conditions. The ZZ isomer was observed to be favoured over the EZ and EE isomers upon methyl group substitution with a bulkier alkyl group in the order: methyl < isopropyl < cyclohexyl < n-pentyl. Qualitatively it has been shown that a bulkier N-pentyl group increases the barrier to rotation around the (S)CN( alkyl)(para-X-Ph) bond over the N-methyl group and this leads to higher concentrations of the ZZ isomer over the EZ and EE isomers. The combined effects of the electron-donating substituent (X = O-CH3) on the N-(para-X-Ph) group and the bulkier N-alkyl group (n-pentyl) result in highest ZZ concentration (76 %) over EZ and EE isomers in the complex cis-bis(N-pentyl-N-(4-methoxy-phenyl)-N’-2,2-dimethylpropanoylthioureato)platinum(II), cis-[Pt(L1DS, O)2]. The lowest concentration ZZ (27 %) is obtained in the complex cis-bis(N-methyl-N-(4-nitro-phenyl)-N’-2,2- dimethylpropanoylthioureato)platinum(II), cis-[Pt(L3A-S,O)2] when the coordinated ligand has both N-methyl group and N-(4-nitro-Ph) group which both lower the barrier to rotation around the (S)C-N(alkyl)(para-X-Ph) bond. A crystal of the complex cis-bis(N-pentyl-N-(4-methoxy-phenyl)-N’-2,2-dimethylpropanoylthioureato)platinum(II), cis-[Pt(L1D-S,O)2] has been isolated and structurally characterised and was shown to be in the ZZ configuration, which is the major component (76 %) in chloroform. This is the first example of Pt(II) chelates with asymmetrically disubstituted ligands to be reported. / AFRIKAANSE OPSOMMING: Die gedeeltelike dubbelbinding karakter van die koolstof-stikstof-binding van die (S)C-NRR’-moieteit lei tot onsimmetriese dialkiel-gesubstitueerde N,N-dialkiel-N’-asieltioureums, R”C(O)NHC(S)NRR’ (HL) wat E,Zkonfigurasionele isomerie in oplossing besit. Die isomerie is sigbaar in die verdubbelling van die seine van die Nalkielgroepe in die 1H- en 13C-KMR spektra. In een so klas ligande waar R- en R’-groepe nie-ekwivalente alkielgroepe is, is isomerie duidelik sigbaar by 298 K in chloroform. In die ander klas waar R’ steeds ’n alkielgroep is, en R ’n para-gesubstitueerde feniel groep, is die isomerie alleenlik sigbaar by baie laer temperature as gevolg van ’n laer rotasieversperring om die (S)C-N(alkiel)(para-X-Ph)-binding (X = O-CH3, H and NO2). Die elektrononttrekkende aard van die nitrogroep in N-metiel-N-(4-nitrofeniel)-N’-(2,2-dimetielpropanoïel)tioüreum, HL3A en N-(4-nitrofenyl)-N-pentiel-N’-(2,2-dimetielpropanoïel)tioüreum, HL3D lei daartoe dat die E,Z-isomerie van die ligande nie eers by 198 K in dichlorometaan waargeneem word nie. Die verspreiding van die E en Z isomere verskil na gelang van die R en R’ groepe. Verskeie E-isomere van hierdie ligande is geïsoleer en struktureel gekarakteriseer en die (S)C-NRR’-bindingslengte is in ‘n gebied [1.343(3) – 1.329(3) Å] wat korter is as die gemiddelde C-N-enkelbindingslengte van 1.472(5) Å. Die Pt(II) chelate wat afgelei is van die ligande is blootgestel aan die E,Z-konfigurasie isomere van die ongebinde ligande. Die teenwoordigheid van cis-[Pt(ZZ-L-S,O)2], cis-[Pt(EZ-L-S,O)2] en cis-[Pt(EE-L-S,O)2] is maklik waarneembaar deur middel van 195Pt-KMR-spektroskopy wat drie goed geresolueerde seine toon, en dit kan bevestig word met 1H- en 13C-KMR spectra van hierdie komplekse. Die 195Pt kerne is ruimtelik geskakel met die 13C kerne deur vier bindings wat aanleiding gee tot 4J(195Pt-13C)-koppelings met N-CH2- of N-CH3-koolstofatome in ‘n Wkonformasie. Die 195Pt KMR spektra word geskakel met die N-CH2- of N-CH3-protonresonansies in al drie die moontlike ZZ, EZ en EE kompleksisomere. Toekenning van die konfigurasionele isomere is dan bewerkstellig deur middel van ‘n kombinasie van lae magneetveld 13C-KMR spectra en hoë resolusie gHSQC (1H/13C) KMR experimente. 1H-KMR-rotasiedinamiek studie toon dat die rotasiegrens, ΔG≠, om die (S)C-N(Me)(para-X-Ph)-binding in cisbis( N-metiel-N-(4-metoksifeniel)-N’-2,2-dimetielpropanoïeltioureato)platinum(II), cis-[Pt(L1A-S,O)2]; cis-bis(Nfeniel- N-metiel-N’-2,2-dimetielpropanoïeltioureato)platinum(II), cis-[Pt(L2A-S,O)2] en cis-bis(N-metiel-N-(4- nitrofeniel)-N’-2,2-dimetielpropanoïeltioureato)platinum(II), cis-[Pt(L3A-S,O)2] komplekse was met die volgende orde bepaal: (elektron-ontrekkende groep) NO2 < H < (elektron-skenkende groep) O-CH3. Die ZZ-isomeer blyk by voorkeur te vorm bo die EZ- en EE-isomere in dieselfde orde as hierbo wat betref para-substituent aan die Nfenielgroep. Die 1H dinamiese KMR tendencies ten opsigte van die rotasiegrens, ΔG≠, om die (S)C-N(Me)(para-XPh)- binding is gekomplimenteer met DFT-linêre organgs berekeninge. Die isomer verspreidings blyk ook beïnvloed te word deur die oplosmiddel polariteit en die temperatuur waarby die verspreidings bepaal is, buiten die elektroniese invloed van die para-substituent aan die N-fenielgroep. Die ZZ, EZ en EE isomeer verspreiding van komplekse wat afgelei is van N-alkiel-N-(para-X-Ph)-N’-asieltioureums met veranderlike N-alkiel substituente (metiel, isopropyl, sikloheksiel, en n-pentiel) is vasgestel deur middel van die 195Pt KMR wat opgeneem is onder identiese kondisies. Die ZZ-isomeer blyk die verkose isomeer te wees bo die EZen EE-isomere waar die metiel substituent vervang word met ‘n groter alkiel groep in die orde van: metiel < isopropiel < sikloheksiel < n-pentiel. Dit is kwalitatief getoon dat die groter N-pentielgroep die rotasiegrens verhoog vir rotasie om die (S)C-N(alkiel)(para-X-Ph)-binding bo dié van die N-metielgroep wat aanleiding gee tot hoër konsentrasies van die ZZ-isomeer relatief tot die EZ- en EE-isomere. Die gekombineerde uitwerking van die electron-skenkende substituent (O-CH3) op die N-(para-X-Ph)-groep en die groter N-alkiel groep (n-pentiel) gee aanleiding tot die hoogste ZZ-konsentrasie (76%) bo EZ- en EE-isomere in die kompleks cis-bis(N-pentiel-N-(4- metoksifeniel)-N’-2,2-dimetielpropanoïeltioureato)platinum(II), cis-[Pt(L1D-S,O)2]. Die laagste konsentrasie ZZ (27%) is verkry in die kompleks cis-bis(N-metiel-N-(4-nitrofeniel)-N’-2,2-dimetielpropanoïel)tioureato)platinum(II), cis-[Pt(L3A-S,O)2] waar die gekoördineerde ligand beide die N-metiel- sowel as die N-(4-nitro-Ph)-groep, wat albei die rotasiegrens van die (S)C-N(alkiel)(para-X-Ph)-binding verlaag. ‘n Kristalstruktuur van die kompleks cis-bis(N-pentiel-N-(4-metoksifeniel)-N’-2,2-dimetielpropanoïeltioureato) platinum(II), cis-[Pt(L1D-S,O)2] wat geïsoleer is, is struktureel gekarakteriseer en is in die ZZ-konfigurasie, wat die hoofkomponent (76%) is in chloroform. Hierdie is die eerste voorbeeld van Pt(II) chelate met asimmetriese digesubstitueerde ligande om geraporteer te word.

Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Pt(JV) complexes with S, 0-donating aroylthioureas have been synthesized by oxidative addition of elemental halogens to the Pt(JJ) precursors, leading to the first-reported crystal structures of Pt(JV) with this class of ligand. The treatment of Pt(II) complexes of N,N-diethyi-N'-benzoylthiourea with 12, Br2 and Cl2 leads to facile oxidative addition of the halogens to the platinum center, yielding several geometric isomers, as determined by 195Pt NMR; the products cis-bis(N ,N-diethyi-N' -benzoylthioureato )diiodoplatinum(IV), 26, and cisbis( N,N-diethyl-N'-benzoylthioureato)dibromo-platinum(IV), 27, have been isolated and structurally characterized. Reaction of cis-/trans-bis(N-benzoyi-N'-propylthiourea-kS)dibromoplatinum(II) with Br2, similarly results in oxidative addition of the dihalogen, yielding the product trans-bis(N-benzoyi-N'propylthiourea- kS)tetrabromoplatinum(IV), 29. lz, however, does not undergo oxidative addition to cis! trans-bis(N-benzoyi-N' -propylthiourea-kS)diiodoplatinum(II), instead the iodine inclusion compound trans-bis(N-benzoyl-N'-propylthiourea-kS)diiodoplatinum(II) diiodine, 28, was isolated. Short intermolecular I··· I interactions in crystals of compounds 26 and 28 lead to infinite chains of weakly linked molecules in the respective solids. 195Pt NMR reveals that the 3: 3 Pt(II) metallamacrocycle of 3,3,3',3'-tetra(n-butyl)-l,l'terephthaloylbis( thiourea) undergoes stepwise oxidative addition of 12 or Br2 to each of the Pt(II) centers, upon treatment with the dihalogens. Treatment of the 2: 2 Pt(II) complex of 3,3,3',3'-tetraethyl-1,1'isophthaloylbis( thiourea) with 12 also results in the oxidative addition of the halogen, yielding a 2 : 2 trans-Pt(IV)-iodo metallamacrocycle, 35. The corresponding trans-Pt(IV)-X (X= Br, Cl) complexes were synthesized by oxidative addition in an electrolytic cell containing the 2 : 2 Pt(II) precursor and an appropriate halide salt in dichloromethane. The 2: 2 trans-Pt(IV)-X (X= I, Br, Cl) metallamacrocycles, 36 an 37, were isolated and structurally characterized. Intermolecular 1···1 interactions between molecules of 35, in crystals of the compound, result in chains of weakly connectedmolecules in the lattice. 195 Pt NMR is used as a sensitive probe for studying the hydration/solvation spheres of the PtX/ (X = Cl, Br) anions, and to investigate the occurrence of {Na + [PtCl/"]}" contact ion-pairing in non-aqueous solutions. The 195Pt NMR chemical shifts of the Pt~2 • (X = Cl, Br) anions in D20 and in various organic solvents have been determined, and are discussed with regard to solvent polarities and donor and acceptor properties. The non-linear variations of bp1•195 for the anions with changing bulk composition in aqueous binary mixtures with the organic solvents, suggest that the anions are preferentially solvated by the organic solvents relative to water. The anion solvation sphere compositions with changing bulk composition, as well as preferential solvation equilibrium constants, K11 ", are determined from the NMR data. Significant non-linear variations of the 195Pt NMR chemical shift for methanol and acetonitrile solutions of PtXt (X = Cl, Br) ·with increasing NaCI04 concentrations indicate the occurrence of {Na+[PtX6 2_]}_ contact ion-pair formation in these solutions. By contrast, the variation of Dp1•195 for aqueous solutions of the halogenoplatinate anions with increasing sodium perchlorate concentration is slight, revealing that Na+···PtXe?- ion association is not favoured in the aqueous medium. The 195Pt chemical shift variations are used to estimate conditional ion-pair formation equilibrium quotients, Q (M"\ for {Na+[Ptxi·Jr contact ion-pair formation in water, methanol and acetonitrile. The estimated Q values illustrate that the extent of {Na+[Ptxi·Jr ion-pairing increases in these solvents in the order water< methanol< acetonitrile, which is in accordance with the solvent donor and acceptor properties. / AFRIKAANSE OPSOMMING: Pt(JV) komplekse met S, 0-donerende aroi"eltioiireum ligande is deur middel van die oksidatiewe addisie van halogene aan Pt(JJ) uitgangskomplekse gesintetiseer; die kristalstrukture van die Pt(IV) komplekse met hierdie tipe ligande word vir die eerste keer gerapporteer. Die behandeling van die Pt(II) komplekse van N,N-dietiel-N'-bensoieltioiireum met 12, Br2 en Cl2 gee geredelik aanleiding tot die oksidatiewe addisie van die halogene aan die platinum sentrum, en lei, volgens bepaling met 195Pt KMR, tot die vorming van verskeie geometriese isomere; die produkte cis-bis(N,Ndietiel- N' -bensoieltioiireato )di-jodoplatinum(IV), 26, en cis-bis(N,N-dietiel-N' -bensoieltioiireato )dibromoplatinum( IV), 27, is geisoleer en kristallografies gekarakteriseer. Reaksie van cis-/trans-bis(N-bensoiel-N'propieltioiireum- IGS)dibromoplatinum(II) met Br2, lei ooreenkomstiglik tot oksidatiewe addisie van die halogeen, met trans-bis(N-bensoiel-N' -propieltioiireum-IGS)tetrabromoplatinum(IV) as produk, 29. 12 ondergaan egter nie oksidatiewe addisie aan cis-ltrans-bis(N-bensolel-N' -propieltioiireum-IGS)dijodoplatinum( II) nie; 'n verbinding waarin h ingesluit word in 'n kristalstruktuur met trans-bis(N-bensoielN'- propieltioiireum-IGS)di-jodoplatinum(II), word geisoleer, 28. Kort intermolekulere 1···1 interaksies in die kristalstrukture van verbindings 26 en 28 lei tot die ontstaan van swak-gebonde molekuul-kettings in die kristalle. 195Pt KMR dui aan dat met behandeling van die 3 : 3 Pt(II) metallomakrosikliese kompleks van die 3,3,3' ,3 '-tetra(n-butiel)-1, 1 '-tereftaloielbis(tioiireum) ligand met 12 of Br2, daar stapsgewyse oksidatiewe addisie van die halogene aan die Pt(II) ione in die kompleks plaasvind. Behandeling van die 2 : 2 Pt(II) kompleks van 3,3,3' ,3 '-tetraetiel-1, 1 '-isoftaloielbis(tioiireum) met 12 gee ook aanleiding tot oksidatiewe addisie, met 'n 2 : 2 trans-Pt(IV)-jodo metallomakrosikliese kompleks as produk, 35. Die ooreenkomstige trans-Pt(IV)-X (X = Br, Cl) komplekse is gesintetiseer deur middel van oksidatiewe addisie in 'n elektrolitiese se! wat die 2 : 2 Pt(II) uitgangskompleks bevat tesame met 'n toepaslike haliedsout in dichlorometaan. Die 2 : 2 trans-Pt(IV)-X (X = I, Br, Cl) komplekse, 36 en 37, is geisoleer en kristallografies gekarakteriseer. lntermolekulere I··· I interaksies tussen molekule in kristalle van verbinding 35, gee aanleiding tot kettings van swak-gebonde molekule in die struktuur. 195 Pt KMR word gebruik om die hidraterings-/solvaterings-sfere van die PtX/" (X = Cl, Br) anione te ondersoek, asook om die voorkoms van {Na + [PtCIX/}F kontak-ioonparing in nie-waterige oplosmiddels te bestudeer. Die195Pt KMR chemise verskuiwing van die PtXl" (X= Cl, Br) anione in D20 en in verskeie organiese oplosmiddels is bepaal, en word bespreek met verwysing na die polariteite asook die donor- en akseptoreienskappe van die oplosmiddels. Die nie-lineere variasies van Op1_195 vir die anione met veranderende oplosmiddelsamestelling in waterige binere mengsels met die organiese oplosmiddels, dui aan dat die anione by voorkeur deur die organiese oplosmiddels gesolvateer word. Die solvateringssamestelling van die anione met veranderende oplosmiddelsamestelling, asook ewewigskonstantes vir die voorkeur-solvatering deur die organiese oplosmiddels, K11 ", word met behulp van die KMR data bepaal. Beduidende nie-lineere variasies van Op1_195 in metanol en asetonitriel oplossings van PtXl" (X = Cl, Br) met toenemende NaC104 konsentrasies, dui op die voorkoms van {Na +[PtClxl-]}- kontak-ioonparing in die oplossings. Die variasies van Op1_195 in waterige oplosings van die anione met toenemende NaC104 konsentrasies is egter minder beduidend, waaruit afgelei kan word dat ioonparing nie in die waterige medium bevoordeel word nie. Die 195Pt chemiese verskuiwings word gebruik om kondisionele ioonpaarvormings-ewewigskwosiente, Q (M-1 ), vir die vorming van {Na+[PtCIXtJr in water, metanol en asetonitriel af te lei. Die Q-waardes dui in ooreenstemming met die donor- en akseptoreienskappe van die onderskeie oplosmiddels aan dat die voorkoms van kontak-ioonparing toeneem vir die oplosmiddels in die volgorde water < metanol < asetonitriel.

Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Radiochemical separation of 103Pd from natAg, usmg a 66 MeV proton-induced reaction at iThemba LABS, was studied and a radiochemical method was developed for the separation. For the separation, which comprises the separation of Pd from a large amount of target material (16 g Ag), as well as Rh radioisotopes produced from decay of their Pd parents (mainly 101Rhand IOORh),three ion exchange resins were tested: a Chelex 100 chelating resin, the AG 1-X8 anion exchange resin and a AG MP-I anion exchange resin. For the optimum elution ofPd from the latter two resins, two elution curves using water and 5% ammonia solution, were obtained. With an average recovery of 97.4% and sharper elution curve from the macroporous AG MP-I, this resin was finally chosen for routine production. To achieve the separation, a simple, easily operated radiochemical processing system was designed and installed in a hot cell. Radiochemical separation of 103Pd from a Rh target was also studied and several cation and anion exchange resins were tested. A carrier-free separation of 103Pd was developed, using an AG 1-X8 anion exchange resin. Bombarded tablets of RhCh.3H20, as the targets, were used for these separations. The procedure, originally designed for the separation of Pd from Cu and Rh, was modified using H202 for the oxidation of Ru prior to the sorption on the resin and successfully used for the separation of isotopes of Rh from the isotopes of Pd, Ru, Tc, Nb, Mo, Zr and Y, which were produced by 400 MeV 160_ and 12C-induced RhCb.3H20 targets. To elute the Pd from the resin, 5% ammonia solution was used; the recovery was about 92%. To prepare the Rh target for routine production, an electroplating method of Rh on a Cu substrate was developed. Rh(CI04)3, in 0.5 M perchloric acid, was used as the electrolyte bath. The electroplated Rh was then dissolved by an alternating current technique, using 6 M HCI and a current density of 2 Alcm2. For production of the seeds, I03Pd was sorbed on the weakly basic anion exchange resin Amberlite IRA-93 (600-700 Il), by recycling a 0.5 M Hel solution of Pd through a 0.5 cm x 1 cm column for 2 hours. The distribution of I03Pd on the resin beads was measured and RSD of5.7% was obtained. A funnel was designed to transfer the I03Pd-loaded resin beads into the Ti tubes to prepare the seeds (0.7 mm LD., 0.8 mm D.D., and 4.5 mm length). To enclose the tubes as capsules, the end caps were made from 0.02 mm Ti sheet and several pieces were designed and machined for the welding of the caps to the tubes. A spotwelding machine was used for the welding, after small, but vital modifications. / AFRIKAANSE OPSOMMING: Palladium-l03 kan volgens twee produksieroetes by iThemba LABS vervaardig word, naamlik deur die volgende protongeïnduseerde reaksies: natAg(p,xn)lo3Cd (ty,=7.3 m) ~ 103Ag (ty,=1.1 h) ~ 103Pden I03Rh(p,n) ~ 103Pd. 'n Radiochemiese metode om 103Pd van die Ag-skyfmateriaal te skei, is ontwikkel. Hierdie metode, wat gebaseer is op anioonuitruilerchromatografie met die makroporeuse hars AG MP-I, behels die skeiding van I03Pd van 'n groot hoeveelheid skyfmateriaal (16g Ag), sowel as van Rh-radionukliede (hoofsaaklik looRh en IOlRh), wat geproduseer word deur die verval van hulle Pd-moederisotope. As die Pd met 5% ammonia oplossing geëlueer word, is 'n 97.4% herwinning moontlik. 'n Radiochemiese paneel is ontwerp, gebou en in 'n warmsel geïnstalleer vir roetine produksie. 'n Metode om Rh op 'n kopersubstraat te elektroplateer is ook ontwikkel om 'n Rh-skyf te verkry vir die protonbombardement. 'n Oplossing van 0.5 M HCI04 - Rh(HCI04)3 is as die elektrolietbad gebruik. Die geëlektroplateerde Rh is opgelos in 6 M HCI deur gebruik te maak van 'n wisselstroomtegniek, met 'n stroomdigtheid van 2A1cm2. 'n Metode om "draervrye" I03Pd vanaf die Rh-skyfmateriaal te skei, is ook ontwikkel. Gebombardeerde pille van RhCh.3H20 is as skywe gebruik in die onaktiewe studies. AGI-X8 anioonuitruilerhars is vir hierdie skeidings gebruik en daar is gebruik gemaak van 'n metode wat oorspronklik ontwerp is vir die skeiding van Pd van Cu en Rh. Hierdie prosedure is net effens aangepas deur H202 te gebruik vir die oksidasie van Ru, alvorens dit op die hars gesorbeer is. Hierdie metode is ook suksesvol gebruik vir die isolering van Rh van radionukliede van Pd, Ru, Tc, Nb, Mo, Zr, ens, wat geproduseer is deur 400 MeV 160_ en 12C-geïnduseerde reaksies met Rh in RhCi).3H20 skywe. 5% ammoniakoplossing is gebruik om die Pd uit die hars te elueer, met 'n herwinning van 92%. Om die saadjies vir implantering te maak, is 103Pd op 'n matige basiese anioonuitruilerhars Amberlite IRA-93 gesorbeer deur 'n 103pd-oplossing, in 0.5 M Hel, deur 'n 0.5 ' lcm kolom te hersirkuleer vir 2 uur. 'n Tregter is ontwerp om die I03Pd-gelaaide harskorrels oor te dra na die titaanbuisies (0.7 mm binnedeursnit, 0.8 mm buitedeursnit en 4.5 mm lank). Om die buisies te verseël, is dekseltjies uit 'n 0.02 mm titaanplaat gesny. Verskeie dekseltjies is gemasjieneer om op die buisies vas te sweis. 'n Punt-sweismasjien is gebruik vir die sweiswerk nadat geringe, maar belangrike, aanpassings aan die masjien gedoen is.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The work in this dissertation provides structural and kinetic insight into the mechanism of action of quinoline antimalarial drugs which may aid rational drug design. Quinoline antimalarial drug-ferrihaem (Fe(III)PPIX) complexes were investigated. Single crystal Xray diffraction (SCD) structures of the complexes formed between Fe(III)PPIX and the quinoline methanol antimalarials quinine, quinidine and mefloquine have been determined, and are the first observed structures of complexes formed between free Fe(III)PPIX and quinoline antimalarial compounds. Quinine, quinidine and mefloquine are shown to have a three-point binding mode to Fe(III)PPIX, which comprises direct coordination of the drug to the Fe(III) centre through its benzylic alcohol functionality, π-stacking between the drug and porphyrin aromatic systems, and intramolecular hydrogen bond formation between the porphyrin propionate group and the protonated quinuclidine nitrogen atom of the drug in the case of quinine and quinidine, and formation of an intramolecular hydrogen bonding network in the case of mefloquine. Extended X-ray absorption fine structure spectroscopy (EXAFS) was use to elucidate structural information of Fe(III)PPIX-drug complexes in solution, and indicates that coordination persists in solution. The protocol for lipid-mediated formation of β-haematin, where monopalmitic glycerol was used as a model lipid, was successfully modified to incorporate antimalarial drugs into the aqueous layer in order to investigate drug activity under biologically-relevant conditions. Four compounds were chosen, namely chloroquine and amodiaquine, both 4- aminoquinolines and quinine and quinidine. IC50 values for the inhibition of β-haematin formation show good correlation with biological activities determined against a chloroquine-sensitive Plasmodium falciparum strain. The lipid-water interface system was further used to investigate the effects of quinine, quinidine chloroquine and amodiaquine on the kinetics of β-haematin formation. The results led to the development of a kinetic model based on the Avrami equation and the Langmuir isotherm. The data strongly support a mechanism of antimalarial drug action by adsorption to the growing face of haemozoin, with precipitation of Fe(III)PPIX at high drug concentrations accounting for decreased yields. Adsorptions constants (log Kads) determined for each drug show a strong correlation with biological activity. Finally, the first SCD structure of the μ-propionato dimer of Fe(III)PPIX, the structural unit of haemozoin, has been determined as its DMSO solvate. EXAFS suggests that this species is only formed upon nucleation, with the π-π dimer species being favoured in solution. / AFRIKAANSE OPSOMMING: Die werk in die dissertasie verleen struktuur en kinetiese insig in the meganisme van aktiwiteit vir kinolien antimalariamiddels wat kan bydra tot die ontwikkeling van nuwe medisyne. Kinolien antimalariamiddel-ferriheem (Fe(III)PPIX) komplekse was ondersoek. Navorsing is gedoen op die enkelkristal X-straaldiffraksie strukture van die komplekse gevorm tussen Fe(III)PPIX en die kinolien metanol antimalaria middels kinien, kinidien en mefloquine. Die strukture is die eerste komplekse wat waargeneem is tussen vrye Fe(III)PPIX en kinolien antimalariamiddels. Kinien, kinidien en mefloquine het ʼn driepunt bindingsvorm, direkte koördinasie met die Fe(III) deur die bensielalkohol groep, ʼn π- stapel tussen die middel en die porfirien aromatiese sisteem, ʼn intramolekulêre waterstofbinding tussen the porfirienpropionaat funksie en die geprotoneerde kinuklidien stikstofatoom (kinien en kinidien) en ʼn netwerk van intramolekulêre waterstof bindings (mefloquine) insluit. Uitgebreide X-straal absorpsie fyn struktuur spektroskopie (EXAFS) is gebruik om inligting oor Fe(III)PPIX-middel komplekse in oplossing te verkry en het aangedui dat die koördinasie in oplossing voorkom. Deur gebruik te maak van monopalmitiengliserol as die lipid in the lipid-water interfase sisteem, waar antimalariamiddels suksesvol in die buffer geïnkorporeer was, was die middel se aktiwiteit onder biologiese kondisies geondersoek. Vier middels was gekies naamlik, chloroquine en amodiaquine, albei 4-aminokinoliene en kinien en kinidien om die IC50-waarde vir inhibisie van β-hematien vorming te bepaal. Die IC50 waardes het ʼn goeie korrelasie met biologiese aktiwiteite teen die chloroquine-sensitiewe Plasmodium falciparum stam gewys. Die lipid-water interfase-sisteem was ook gebruik om die effek van kinien, kinidien, chloroquine en amodiaquine op die kineties effek op die vorming van β-hematien te ondersoek. Die resultate het gelei to die ontwikkeling van die kinetiese model gebaseer op die Avrami vergelyking en die Langmuir isoterm. Die data ondersteun ʼn meganisme van middel aksie waar die middel teen die groeiende vlak van hemosoïen kristal adsorbeer. Die neerslag van Fe(III)PPIX wat vorm by hoë konsentrasies, het gelei tot laer opbrengste. Die adsorpsiekonstante (log Kads) bepaal vir elke middel, het goeie korrelasie met biologiese aktiwiteit getoon. Enkelkristal X-straaldiffraksie strukture van μ- propionatodimeer van Fe(III)PPIX, die struktuur eenheid van hemosoïen, was bepaal as ʼn DMSO solvaat. EXAFS het aangedui dat die spesie slegs by kernvorming ontstaan en dat die π-π dimeerspesie in oplossing voorkom.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Phenolic chemistry is quite complex; natural phenolic compounds vary widely in terms of size and chemical properties. The high structural diversity within this family presents severe analytical challenges. High performance liquid chromatography (HPLC) is the preferred method for phenolic analysis; however, conventional HPLC methods offer limited separation power and often provide incomplete separation of the large number of components present in natural phenolic extracts. Multi-dimensional chromatographic techniques have proven much more effective in the analysis of complex samples. The current study explored the potential of comprehensive two-dimensional liquid chromatography (LC×LC) for the characterisation of phenolic compounds in complex natural products, with the emphasis on proanthocyanidins (PACs). Initial work focused on the evaluation of the state of the art in phenolic analysis, to allow information which was used in the development of optimal 1-D separations for use in LC×LC. The combination of hydrophilic interaction chromatography (HILIC) in the first dimension with reversedphase liquid chromatography (RP-LC) in the second dimension afforded an orthogonal and powerful separation system for phenolics, providing separation on the basis of hydrophilicity and hydrophobicity, respectively. A detailed and systematic procedure was therefore developed to allow the optimisation and evaluation of on-line, off-line and stop-flow HILIC×RP-LC methods. Results showed that all three approaches provide much better separation performance than conventional one-dimensional LC (1-D LC) techniques. On-line HILIC×RP-LC offers automation, shorter analysis times, better reproducibility and minimal sample exposure. The off-line and stopflow methods are characterised by much higher peak capacities, but relatively long analysis times. It was also demonstrated that stop-flow operation results in negligible additional band broadening for procyanidins (PCs), implying that this method is an attractive alternative to the off-line method as it offers automation and minimal sample handling. Experimental verification of the predictions based on fundamental principles confirmed the validity of the optimisation procedure for cocoa PCs. The hyphenation of on-line HILIC×RP-LC separation with fluorescence (FL) and mass spectrometry (MS) detection methods provided enhanced resolution in a practical analysis time with the added benefit of selective detection and greater certainty in compound identification. This strategy proved much more powerful, as demonstrated by the identification of the highly complex PACs in grape seeds based on chromatographic retention data in two dimensions and accurate mass information. It was further shown that on-line coupling of HILIC×RP-LC separation with an optimised radical scavenging assay provides an improved approach for screening of individual radical scavengers in complex phenolic fractions, as demonstrated for cocoa, grape seed and green tea extracts. / AFRIKAANSE OPSOMMING: Fenoliese chemie is baie kompleks; natuurlike fenoliese verbindings varieer in terme van beide grootte en chemiese eienskappe. Hierdie hoë strukturele diversiteit binne die familie bied daadwerklike analitiese uitdagings. Hoëverrigtingvloeistofchromatografie (HPLC) is die voorkeurmetode vir fenoliese analises, maar konvensionele HPLC metodes bied egter 'n beperkte skeidingsvermoë en verskaf dikwels onvolledige skeiding van die groot aantal komponente teenwoordig in natuurlike fenoliese ekstrakte. Multi-dimensionele chromatografiese tegnieke is bewys om baie meer effektief te wees met betrekking tot die ontleding van komplekse monsters. Hierdie studie ondersoek die potensiaal van omvattende twee-dimensionele vloeistof chromatografie (LC×LC) vir die karakterisering van fenoliese verbindings in komplekse natuurlike produkte, met die fokus op pro-antosianidiëne (PAC’s). Aanvanklike werk het gefokus op die evaluering van moderne tegnieke vir fenoliese analise – inligting wat in die ontwikkeling van optimale 1-D skeidings vir die toepasing in LC×LC gebruik is. Die kombinasie van hidrofiliese interaksie chromatografie (HILIC) in die eerste dimensie met omgekeerde-fase vloeistof chromatografie (RP-LC) in die tweede dimensie verleen 'n ortogonale en kragtige skeidingsisteem vir fenoliese komponente en verskaf skeiding op grond van onderskiedelik hidrofiliteit en hidrofobiteit. ‘n Gedetailleerde en sistematiese prosedure is dus ontwikkel om die optimisering en evaluering van aan-lyn, af-lyn en stop-vloei HILIC×RP-LC metodes uit te voer. Resultate het getoon dat al drie benaderings baie beter skeidingsvermoë bied as konvensionele een-dimensionele LC (1-D LC) tegnieke. Aan-lyn HILIC×RP-LC bied outomatisering, korter ontledingstyd, beter herhaalbaarheid en minimale monster blootstelling. Die af-lyn en stop-vloei metodes word gekenmerk deur 'n veel hoër piekkapasiteit, maar relatief lang ontledingstye. Daar is ook getoon dat die stop-vloei prosedure geringe bykomende bandverbreding vir prosianodiniëne (PC’s) tot gevolg het, wat beteken dat hierdie metode 'n aantreklike alternatief is vir die af-lyn metode aangesien dit outomatisering bied en minimale monster hantering behels. Eksperimentele verifiëring van die voorspellings gebaseer op fundamentele beginsels bevestig die geldigheid van die optimalisering proses vir kakao PCs. Die koppeling van aan-lyn HILIC×RP-LC skeiding met fluoressensie (FL) en massaspektrometrie (MS) deteksie verskaf verbeterde resolusie binne 'n praktiese ontledingstyd saam met die bykomende voordeel van selektiewe opsporing en groter sekerheid betreffende die verbindings se identifikasie. Hierdie strategie was baie meer kragtig, soos gedemonstreer deur die identifisering van die hoogs komplekse PAC’s in druiwepitte gebaseer op chromatografiese behoud van die integriteit van die data in twee dimensies tesame met akkurate massa inligting. Daar is verder getoon dat aanlyn koppeling van HILIC×RP-LC skeiding met 'n geoptimiseerde radikale vangers deteksie-metode 'n beter benadering bied om die gedrag van individuele radikale vangers in komplekse fenoliese fraksies te bestudeer, soos bewys is vir kakao, druiwepitte en groen-tee ekstrakte.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The cheetah, Acinonyx jubatus, sometimes referred to as "the greyhound of the cats", is probably the most elegant member of the cat family. Formerly widespread in southern Africa it is now threatened with extinction. It occurs in open savanna and light woodland, but also hilly country on occasion. The cheetah is a predator that can reach speeds of more then 110 km/h in short bursts. With a mass of between only 40 to 60 kg, it is not very powerful and cannot defend itself very effectively against carnivores such as the lion and hyaena, for example. This might be the reason why, in order not to advertise its presence, the urine of this animal is practically odourless. In turn, this might explain why no research has so far been devoted to the urine of this animal. In contrast extensive work has been done on the chemical characterisation of the urine of many other carnivores, notably the lion. Extraction of the urine with dichloromethane gave too little material for GC-MS. SPME sampling of the urine itself gave insufficient sample enrichment. Better results were obtained when an SPME-type of headspace sampling, using a larger mass of polydimethylsiloxane, was employed although many of the constituents of the urine could still barely be detected. The compounds identified include a large number of ketones, aldehydes, cyclic and acyclic ethers, carboxylic acids, amides two sulphur compounds in barely detectable quantities, and elemental sulphur. Perhaps the most remarkable result of this thesis is that it was found that the urine of the cheetah, although it is a carnivore, does not contain several sulphur compounds in relatively high concentrations. However, it does contain elemental sulphur. Perhaps a mechanism exists by which the cheetah can convert strongly odorous sulphur containing compounds into the less strongly smelling sulphur. / AFRIKAANSE OPSOMMING: Die jagluiperd, Acinonyx jubatus, 'n roofdier wat tydens 'n jagtog vir kort tye snelhede van meer as 110 km/h kan bereik, is waarskynlik die elegantste lid van die katfamilie. Met sy vaartbelynde liggaam weeg die dier egter slegs tussen 40 en 60 kg kan hy homself nie doeltreffend teen groter roofdiere verdedig nie. Chemiese verbindings, sogenaamde feromone, wat onder andere in die uriene uitgeskei word, word dikwels deur diere gebruik vir gebiedsafbakening en om met ander lede van die spesie te kommunikeer. Die uriene van die jadluiperd is egter feitlik reukloos. Tot dusver is die chemiese samestelling van die uriene van die jagluiperd nog nie ondersoek nie. Ekstraksie van die uriene met dichlorometaan het te min materiaal vir gaschromatografies-massaspektrometriese analise opgelewer, maar bevredigende resultate is verkry deur van 'n verbeterde monsternemingsmetode gebruik te maak. 'n Groot aantal organiese verbindings en twee swawelbevattende verbindings in skaars waarneembare hoeveelhede is in die uriene geïdentifiseer. Daar is egter 'n aansienlike hoeveelheid van die element swawel is in die uriene gevind. Laasgenoemde ontdekking, is die mees verbasende resultaat van hierdie navorsing. Die uitskeiding van swawel in uriene is, sover bekend, eenmalig in die soogdierwêreld. Dit is moontlik dat die jagluiperd oor 'n meganisme beskik om swawelverbindings wat baie sterk ruik om te sit na swawel wat nie so sterk ruik nie. Hierdie meganisme sal die dier se kanse op oorlewing verbeter deur van die swawelbevattende verbindings in sy dieet ontslae te raak sonder om sy teenwoordigheid in die omgewing te adverteer.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Inthis work we aim to put into place a system to separate or immobilise biomacromolecules by means ofimmobilised transition metal ions like nickel(II) or copper(II). Although the concept of immobilised metal affmity chromatography (IMAC) has been around since the early 1960's, the metal ions were always immobilised by covalent modification of the support matrix. Recently the concept of IMAC was applied to membranes, and again the metal ion was immobilised by covalent modification of the membrane surface. Inthis study we covalently modified the support matrix by attaching a linear, EDTA type ligand to the hydroxy end groups of a tri-block copolymer (polyethylene oxide (PEO)m = 129 - polypropylene oxide (PPO)n = 56 - polyethylene oxide (PEO)m= 129), Pluronic® F108. The middle block of this polymer, which is hydrophobic, will non-covalently adsorb onto the membrane surface through hydrophobic interaction. The hydrophilic outer blocks, with the ligand modified end groups, will associate with the aqueous substrate exposing the chelated metal ion for interaction with the bio-macromolecules. This affords a system which is recyclable, without replacing the membranes, simply by stripping the expired ligand modified-polymer and adsorbing fresh polymer. A series of model ligands and their complexes were synthesised and characterised, to study the coordination of the ligand around the metal ions. The model compounds were also essential in characterising the final product - the ligand modified Pluronic. Finally the ligand modified Pluronic was tested for its metal binding capabilities. This was done in aqueous solution by qualitatively comparing the UV-VIS spectra of the modified Pluronic with that of the model ligands and complexes. The spectra indicate that metal coordination does take place. / AFRIKAANSE OPSOMMING: In die studie het ons beoog om 'n sisteem daar te stel vir die skei en immobilisering van bio-makromolekules deur middel van oorgangsmetale soos nikkel(II) en koper(II). Alhoewel die beginsel van geïmmobiliseerde Metaal-ioon Affmiteits Chromatografie (IMAC) reeds sedert die vroeë 1960's bekend is, is die metaal ione geïmmobiliseer deur kovalente modifikasie van die draermaterial. Onlangs is die beginsel van IMAC uitgebrei na membrane en ook hierin is die metaalione geïmmobiliseer deur kovalente modifikasie van die membraanoppervlaktes. In die projek het ons die draermateriaal kovalent gemodifiseer deur 'n lineêre EDT A-tipe ligand te koppel aan die hidroksie eindgroepe van 'n tri-blok ko-polimeer (poli-etileen oksied (PEO)m = 129 - poli-propileen oksied (PPO)n = 56 - poli-etileen oksied (PEO)m = 129), Pluronic® FI08. Die middelste blok van die polimeer, wat hidrofobies is, sal nie-kovalent aan die membraan oppervlakte adsorbeer d.m. v hidrofobiese interaksie. Die hidrofiliese buite blokke, met die ligand-gemodifiseerde eindgroepe, sal assosieer met die waterige substraat en die metal ioon blootstel vir interaksie met die biomakromolekules. Dit stel dus 'n sisteem in plek wat herbenut kan word, sonder om die membrane te vervang, deur eenvoudig die ligand-gemodifiseerde polimeer wat verval het te stroop en te vervang met nuwe polimeer. 'n Reeks modelligande en hul komplekse was gesintetiseer en gekarakteriseer om die koördinasie van die ligande rondom die metaal ione te bestudeer. Dié model verbindings was van groot belang in die karakterisering van die finale produk - die ligand-gemodifiseerde Pluronic. Laastens is die ligand-gemodifiseerde Pluronic getoets vir sy metaal bindings vermoeë. Dit is gedoen deur die UV-VIS spectra van die gemodifiseerde Pluronic kwalitatiefte vergelyk met die spectra van die modelligande en komplekse, in waterige oplossings. Die spectra dui aan dat metaalbinding wel plaasvind.

Thesis (MSc)--Stellenbosch University, 2002. / Please refer to fulltext for abstract / Verwys asb na volteks vir opsomming