Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Two new potentially biodegradable aminopolycarboxylic acid ligands, iminodiglutaric acid tetra sodium salt (IDG-4Na) and iminoglutaricsuccinic acid tetra sodium salt (IGS- 4Na), were synthesized in reasonably good yield and purity. The commercially unavailable precursor for the two ligands, ethyl p-aminoglutarate, was synthesised in high yield and purity, and together with the two ligands were fully characterized by means of melting point measurements and various spectrometric techniques CH-NMR, 13C-NMR, MS and IR). For the first time, an electrochemical study has been conducted on the complexes of these ligands with selected transition metal ions (Zn2+, Cu2+ and Cd2+). An electrochemical technique, cyclic voltammetry (CV), was utilized on the study of the complexing ability of the ligands to the selected metal ions. An electrochemical cell comprising three electrodes was employed: thin film mercury coated carbon microelectrode was used as the working electrode, a Platinum wire as the auxiliary electrode, and a Ag/AgCI as the reference electrode. CV has been used and proven to offer a convenient route towards the determination of metal-ligand complex stability constants in aqueous media". The values of the logarithms of the metal-ligand formation constants obtained by this technique, when compared with other widely used aminopolycarboxylic acids (APCAs), show better complexing ability of the ligands with the transition metal ions. When the two ligands are compared, IGS showed greater affinity towards the selected transition metal ions. This is due to the fact that, in aqueous media, as the side chain ligators decrease, the stabilization energy of the complex increases. The formation stability constants were determined by plotting the change in the reduction potential (ΔE) against solution pH. A process making use of a modification of lingane equation was used. / AFRIKAANSE OPSOMMING: Twee nuwe potensieel bio-afbreekbare amienpolikarboksielsuurligande, iminobiglutaarsuur -tetranatriumsout (IBG-4Na) en iminoglutaarsuksiensuurtetranatriumsout (IGS-4Na), was vervaardig met redelike goeie opbrengs en suiwerheid. Die kommersïeel onverkrygbare voorloper van die twee ligande, etiel-B-aminoglutaraat, was berei met hoë obrengs en suiwerheid, en was saam met die twee ligande ten volle geïdentifiseer deur middel van smeltpunt bepalings en verskeie spektrometriese tegnieke CH-KMR, 13C-KMR, MS en IR.). Vir die eerste keer is 'n elektrochemiese studie uitgevoer op die komplekse van hierdie ligande met selektiewe oorgangsmetaalione (Zn2+, Cu2+, en Cd2+). 'n Elektrochemiese tegniek, sikliese voltametrie (SV), is gebruik om die komplekseringsvermoë van die ligande ten opsigte van die geselekteeerdr metaalione te bestudeer. 'n Elektrochemiese sel wat bestaan uit drie elektrodes is gebruik: 'n Dunlaag kwikelektrode bedek met koolstof is gebruik as die werkselektrode, 'n platinumdraad as die bykomende elektrode en 'n Ag/AgCI elektrode as die verwysingselektrode. SV is voorheen gebruik en bewys as 'n gerieflike metode vir die bepaling van metaalligandkompleksstabiliteitskonstantes in waterige media'. Die waardes van die logaritmes van die metaalligandvormingskonstantes wat verkry word deur hierdie tegniek, soos vergelyk met ander algemeen gebruikte amienpolikarboksielsure (APKSe), vertoon beter komplekseringsvermoë met die ligande deur middel van die oorgangsmetaalione. Wanneer die twee ligande met mekaar vergelyk word, het IGS-4Na groter affiniteit gehad vir die oorgangsmetaalione. Dit is as gevolg van die feit dat die stabiliteitsenergie van die kompleks in waterige media verminder word soos wat die sykettings van die ligande toeneem. Die vormingstabilitietskonstantes was bepaal deur 'n varandering in reduksie potensiaal (ΔE) teenoor die pH van die oplossings te plot. Die grafieke is verkry deur 'n aanpassing van die Lingnane-vergelyking te gebruik.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This investigation comprises the synthesis and characterisation of new macrocyclic ligands with pendant arms appended to the nitrogen donor atoms of 1,5,9-triazacyclododecane (12aneN3) and their coordination to various transition metal ions. The five macrocyclic ligands, 1,5,9-tris[(2S)-2-hydroxypropyl]-1,5,9-triazacyclododecane (THPTACD), 1,5,9- tris(2-hydroxy-2-methylpropyl)-1,5,9-triazacyclododecane (THMPTACD), 1,5,9-tris[(2S)-2- hydroxy-2-phenylethyl]-1,5,9-triazacyclododecane (THPETACD), 1,5,9-tris[(2S)-2- hydroxybutyl]-1,5,9-triazacyclododecane (THBTACD) and 1,5,9-tris(2-mercaptopropyl)- 1,5,9-triazacyclododecane (TMPTACD) were prepared by addition of pendant arms that contain alcohol or thiol end groups to a preformed 12aneN3 macrocycle. The 12aneN3 was synthesised from simple starting materials using 1,3-propanediol and bis(3-aminopropyl)- amine. The macrocycles with oxygen donor atoms on the pendant arms were prepared from the corresponding epoxides whereas for the one that contained sulphur donor atoms, propylene sulphide was used. The reaction progress was followed by 13C and 1H NMR spectroscopy and the final macrocyclic ligands were further analysed by mass spectrometry and in some instances, elemental analysis was also performed. Protonation constants of the free ligands were determined using potentiometric titrations at 25 oC and the ionic strength was kept constant at 0.1000 mol dm-3 using NaNO3. The log K1 values were 11.47, 10.96 and 10.47 for THPTACD, THBTACD and THMPTACD, respectively, whereas the corresponding values of 5.81, 6.02 and 5.94 were obtained for log K2. THPTACD is the most basic mainly due to less steric hindrance whereas THMPTACD is the least basic owing to high steric hindrance to both solvation and formation of strong hydrogen bonds of the protonated species to solvent molecules during the solvation step in a Born Haber-type cycle of the complete process. Protonated THBTACD is the most basic of the three mono-protonated ligands, a result that may be explained in terms of better correlation between inductive and steric effects. The second protonation constant is mostly influenced by inductive effects unlike the first protonation constant which is mostly determined by steric effects. The third protonation constant could not be established because of lack of sensitivity of the glass electrode in very high acidic medium. The complex stability constants of Co(II), Zn(II), Cd(II) and Pb(II) cations were similarly determined using potentiometric titrations at 25 ¡ÆC in 0.1000 mol dm-3 NaNO3. Log K values with THPTACD are 15.45, 21.22, 14.03 and 16.11 for Co(II), Zn(II), Cd(II) and Pb(II), respectively. THBPTACD has corresponding values of 13.93, 20.02, 13.55 and 15.01, whereas for THMPTACD the values of 14.63, 18.08, 12.91 and 14.36 log units were obtained. The Zn(II) 1:1 complexes are the most stable and those of Cd(II) the least stable. A crystal structure determination of [Zn(THPTACD)]2+ shows that optimal interaction between the Zn(II) metal ion and the donor atoms with their short Zn(II)-N bond lengths occurs. The short Zn(II)-N distances indicate that the metal ion is situated very close to the macrocyclic hole. On the other hand, each half of the hydrogen-bonded dimeric molecular structure of [Cd2(THPTACD)2]4+ has long Cd(II)-N bond lengths. Although metal nitrates, perchlorates and acetates were used in attempted crystal structure determinations, only metal nitrates formed suitable crystals. THPTACD complexes with Co(II), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) were subjected to such determinations. Each central metal ion in these complexes is six coordinate to the three N atoms of the parent macrocyclic ring on one plane and the three O atoms of the pendant hydroxypropyl arms forming another plane on the other face of the metal ion. The geometry of all six molecular structures is pseudo octahedral with the Cu(II) complexes being the most twisted towards a trigonal prismatic arrangement. The change towards trigonal prismatic can be attributed to packing forces overriding octahedral crystal field stabilisation effects. The overall chirality of the isomorphic complexes of Zn(II), Co(II), Mn(II), Ni(II) and Cu(II) with THPTACD is [¥Ë((2¥ë.)¥ä.¥ä)] whereas the overall chirality of each half of the dimeric [Cd2(THPTACD)2]4+ complex is [¥Ë(¥ë.(2¥ä.)¥ä)]. The Cu(II) complex with THPETACD has the same overall chirality as the Cu(II) complex with THPTACD but is less twisted towards trigonal prismatic geometry. Both Cu(II) complexes exhibited strong evidence of Jahn-Teller tetragonal distortion in the solid state with tetragonality parameter values of 0.87 and 0.81, respectively. The structure of a new di-¥ì-chloro bridged binuclear complex of Cd(II)-12aneN3 was also determined. The molecule contains an inversion centre coinciding with the crystallographic centre of symmetry. Finally, the molecular structure of the protonated 1,5-bis[(2S)-2- hydroxybutyl]-1,5,9-triazacyclododecane shows that the oxygen donor atoms of the two pendant arms are pre-organised for meridional coordination. The hydrogen bond network in this structure emphasises the important role that such weak interactions play in stabilising the proton even in solution during determination of protonation constants in triazamacrocycles with pendant arms carrying oxygen donor atoms.

Thesis (PhD (Chemistry and Polymer Science))—University of Stellenbosch, 2006. / This study describes the exploitation of numerous donor ligand possibilities presented by selected nitrogen-rich heterocyclic ligands towards gold(I). The preparation and structural characterisation of novel gold(I) complexes, apart from conventional gold(I) bonding possibilities, also encompassed a study of bi- and polytopic bonding modes within a range of multifunctional ligands.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In this study, two novel ligands were synthesized and separately two crown ether derivatives were all immobilized onto four different silica substrates. These immobilized ligand systems were used to extract six different metal and metalloid ions in water. The extraction capacity of the different immobilized ligands was compared with each other to determine whether the substrates had any influence on the extraction capabilities of these ligands. After the extraction experiments, recovery of the immobilized ligands was attempted by re-protonating the ligands so as to displace the metal ions. Two free parent ligands, 1,4,7-tris-[(S)-2-hydroxypropyl]-1,4,7-tri-azacyclodecane (THTD) and 1,4,8-tris-[(S)-2-hydroxypropyl]-1,4,8-tri-azacycloundecane (THTUD), were synthesized. Previous formation constant data indicated that THTD and THTUD form very stable complexes with Cd2+ which should make these ligands ideal for the extraction of Cd2+. These two ligands are less symmetric due to the carbon bridges between the nitrogen atoms, which differ in length. This gives the ligands the special feature that they can form five - and six membered rings during complexation with the metal ions. The ligands were fully characterized by NMR, mass spectrometry and elemental analysis. Characterization of the silica substrates was done using BET, low angle X-ray diffraction and FTIR. MCM-41 has the highest surface area, followed by SBA-15, Si gel (60 Å) and HMS. Although MCM-41 has the largest surface area, it was not the best support to use. HMS and Si gel (60 Å) have the smallest and almost identical surface areas. Yet, Si gel (60 Å) was a far better support to use than HMS, and even better than MCM-41. The worst supports were SBA-15 and HMS. A spacer, 3-Glycidyloxypropyl-trimethoxysilane (glymo), was introduced to immobilize the ligands to the silica substrates. Solid state NMR and FTIR analysis confirmed that the spacer could indeed be successfully immobilized on the various silica supports. The immobilized ligands were fully characterized with the use of solid state NMR and FTIR. The thermal stability of the immobilized ligands was determined by means of TGA. The immobilized ligands are stable up to 200ºC where after they started to disintegrate. According to literature, 15-crown-5 and 18-crown-6 are suitable ligands for the extraction of Sr2+ and UO22+. Since these ligands were to be immobilized, (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 were used because of the amino group that can be used as an anchor for immobilization. To immobilize these ligands onto the activated silica substrates, two methods were used: 1) directly onto the substrate by using the amino groups at the end of the carbon arm and 2) by means of the glymo spacer which connects the (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 to the silica substrates. The immobilization was confirmed and the ligand-substrate moiety fully characterized by solid state NMR and FTIR. The thermal stability of the immobilized crown ethers was determined by means of TGA as stable up to 200ºC where after they disintegrated. Extraction experiments were conducted at 25ºC and atmospheric pressure. The extractions were done at pH values of 4.5 and 5.9. The extraction capacity of the immobilized ligands was determined by ICP analysis. As expected, the extraction done at pH 5.9 was significantly better than at pH 4.5. Cr6+ was the best-extracted metal ion. The best extraction results were obtained with Si gel (60 Å) as support. It was also noticeable that the extraction capacity increased with a spacer added to the support, except for the extraction of UO22+. Better extraction for the uranyl was obtained using the 15-crown-5 and 18-crown-6 immobilized directly onto the supports, rather than with a spacer added. Recovery of the metal ions and the immobilized ligands was attempted, but without success. This aspect will be examined again in future work. In conclusion, ligands were successfully synthesized and immobilized. These immobilized ligands produced moderate extraction results with a number of metal ions from aqueous solution. / AFRIKAANSE OPSOMMING: Hierdie studie behels die sintetisering van 2 nuwe ligande en die immobilisering daarvan, te same met 2 kroon eters, op vier verskillende silika substrate. Die geïmobiliseerde ligande is gebruik vir die ekstraksie van verskillende metaal - en metaloied ione uit water. Die ekstraksie kapasiteit van die onderskeie geïmobiliseerde ligande is vergelyk om te bepaal of die substrate ‘n uitwerking op die ekstraksie vermoeë van die ligande het. Herwinnings eksperimente is uitgevoer deur die verplasing van die geadsordeerde metaal ione deur middel van reprotonasie van die ligande. Twee nuwe azamakrosikliese basis ligande, 1,4,7-tris-[(S)-2-hidroksipropiel]-1,4,7-tri-azasiklodekaan (THTD) en 1,4,8-tris-[(S)-2-hidroksipropiel]-1,4,8-tri-azasikloundekaan (THTUD), is gesintetiseer. Vormings konstante data dui daarop dat THTD en THTUD uiters stabiele komplekse met Cd2+ vorm wat hierdie ligande dus geskik behoort te maak vir die ekstraksie van Cd2+. Die twee ligande toon ook ‘n mindere mate van simmetrie as gevolg van die verskillende lengtes van die koolstof brûe tussen die stikstof atome. Hierdie eienskap verskaf aan die ligande die moontlikheid om beide vyf- en sesledige ringe vorm tydens kompleksering met die metaal ione. Die ligande is ten volle gekarakteriseer deur middel van KMR-metings, massa-spekstroskopie en element analise. Karakterisering van die silika substrate [Si gel (60 Å), MCM-41, SBA-15, and HMS] sluit in BET, lae hoek X-straaldiffraksie en FTIR. MCM-41 het die grootste oppervlakte, gevolg deur SBA-15, Si gel (60 Å) en HMS. Ten spyte van die feit dat MCM-41 die grootste oppervlakte het, was dit egter nie die beste subtraat om te gebruik nie. Die interne areas van die uiters groot porie-oppervlaktes van MCM-41 is nie toeganklik vir immobilisering nie a.g.v. die uiter klein porie-openinge. Si gel (60 Å) en HMS het die kleinste oppervlak areas. Si gel (60 Å) is ‘n baie beter substraat om te gebruik as HMS, en selfs ook beter as MCM-41 aangesien die totale oppervlakte van die Si gel (60 Å) gebruik kan word. Die mees ongeskikte substrate was SBA-15 en HMS. Die alreeds klein oppervlak areas word verder “verklein” a.g.v. die klein porie openinge wat die interne oppervlekte van die porieë ontoegangklik maak. ‘n Verbinder, 3-Glysidieloksipropiel-trimetoksisilaan (glymo) is gebruik om die ligande op die silika substrate te immobiliseer. Vaste toestand KMR en FTIR analise het bevestig dat die verbinder suksesvol geïmmobiliseer is op die onderskeie silika substrate. Die geïmmobiliseerde aza makrosikliese ligande is ten volle gekarakteriseer deur vaste toestand KMR en FTIR. Die termiese stabiliteit is bepaal d.m.v GTA en die geïmmobiliseerde ligande is stabiel tot 250ºC. Die basis ligande 15-kroon-5 an 18-kroon-6 is uiters geskik vir die ekstraksie van Sr2+ en UO22+. Om hierdie kroon eters te immobiliseer, is (2-aninometiel)-15-kroon-5 en (2-aninometiel)-18-kroon-6 gebruik. Die amino groep dien as anker vir die immobilisering. Twee metodes van immobilisering op silika is gebruik: 1) direkte immobilisering op die substraat en 2) immobilisering d.m.v. die glymo verbinder. Die immobilisering is bevestig en die ligand-substraat funksionel groep is gekarakteriseer d.m.v. vaste toestand KMR en FTIR. Die termiese stabiliteit van die geïmmobiliseerde kroon eters is bepaal d.m.v. GTA en is stabiel tot 200ºC. Ekstraksie eksperimente is uitgevoer by 25ºC en atmosferiese druk. Die ekstraksies is uitgevoer by pH waardes van 4.5 en 5.9. Die adsorpsie kapasiteit van die geïmmobiliseerde ligande is bepaal d.m.v. IGP analise. Soos verwag is die ekstraksie by pH 5.9 beter as by pH 4.5. Cr6+ ekstrksie was die hoogste met al die die ligande geïmmobiliseerd op die onderskeie substrate. Si gel (60 Å) was die beste substraat om te gebruik. Die ekstraksie kapasiteit van al die metaal ione het verbeter met die toevoeging van ‘n verbinder, behalwe vir UO22+. Beter ekstraksie van die UO22+ is verkry met die gebruik van die kroon eters wat direk op die substrate geïmmobiliseer is, eerder as met ‘n verbinder toegevoeg. Herwinning van die metaal ione en die ligande is probeer deur standard filtrasie. Na die filtrasie is die geïmmobiliseerde ligande en substrate met water gewas. Die filtreerpapier en ligande is met HNO3 behandel, maar van die metaal ione het egter op die filtreer papier agter gebly en die IGP resultate het ‘n hoër herwinning getoon as wat tydens die ekstraksie verkry is. Hierdie aspek sal weer in die toekoms ondersoek moet word. Die ligande is suksesvol gesintetiseer en geïmmobiliseer. Hierdie geïmmobiliseerde ligande toon gemiddelde ekstraksie resultate met ‘n aantal metaal ione uit waterige medium by ‘n pH van 5.9.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Benzoxazoles are an important class of π-electron-excessive, benzene-fused heterocyclic compounds found in natural products and display a wide range of pharmacological applications. It is therefore a widely used starting scaffold for drug and agrochemical discovery programs. Other applications include: chiral auxiliaries in asymmetric reactions, chiral receptors for the resolution of racemic mixtures, fluorescent whitening dyes, various photochromic materials and as ligands for a wide range of catalytic reactions. Due to our interests in resorcinarenes, we came across 4-hydroxybenzoxazoles, a structural motif that has not been explored as potential asymmetric ligands. In this thesis it was attempted to investigate the synthesis, functionalisation and coordination chemistry of these compound class and finally look at a method of synthesising chiral 4-hydroxybenzoxazoles from amino acids. A small library of achiral 4-hydroxybenzoxazoles were synthesised in good yields. These compounds were then reacted with various transition metals, of which only the Pd-salts proved to return any usable compounds. The first structural evidence of the bonding of 4- hydroxybenzoxazoles was recorded from single crystal X-ray diffraction analysis of the coordination compounds that formed. Different coordination modes were recorded, depending on the ligand and the Pd-salt used. The PdCl2 compounds were also tested for catalytic activity with a Heck reaction, showing good conversions for the reaction between iodobenzene and styrene to form stilbene. Further examination pointed to the ligands playing an insignificant role in the reaction and the products possibly due to only the PdCl2’s reactivity. During this period it was also attempted to functionalise the phenol group with P(III) groups and repeat the coordination and catalytic studies. Efforts to synthesise these compounds were not successful, with oxidation of the P(III) to P(V) groups or degradation of these compounds. Efforts to synthesise these via phosphorous protection, utilising BH3 or the in situ trapping of the compounds with transition metals, were also not successful. During the trapping experiments the phosphinite and Pd-salt formed a re-arranged product that is a known and useful catalyst on its own. Finally a small library of chiral benzoxazoles and 4-hydroxybenzoxazoles were synthesised, starting from amino acids and utilising a Mitsunobu reaction to perform the ring closing. Antimicrobial tests with these compounds did not return any appreciable results. / AFRIKAANSE OPSOMMING: Bensoksasool is 'n belangrike klas van π-elektron-ryk, benseen-saamgesmelte heterosikliese verbindings wat in natuurlike produkte voorkom en 'n wye verskeidenheid van farmakologiese funksies vertoon. Dit is dus 'n baie algemene basis struktuur vir dwelm- en landbouchemiese ontdekkings programme. Ander gebruike sluit in: chirale ligande in asimmetriese reaksies, chirale reseptore vir die resolusie van rasemiese mengsels, fluoresserende verwittings kleurstowwe, verskeie fotochromiese materiaal en as ligande vir 'n wye verskeidenheid van katalitiese reaksies. As gevolg van ons belangstelling in resorsinarene, het ons op 'n strukturele motief afgekom wat nog nie ondersoek is as potensiële asimmetriese ligande nie, die 4- hidroksiebensoksasole. In hierdie tesis is gepoog om die sintese, funksionalisering en koördinasie chemie van hierdie klas verbindings te ondersoek en uiteindelik 'n metode te ontwikkel om die sintese van chirale 4-hidroksiebensoksasole vanaf aminosure te bewerkstellig. 'n Klein biblioteek van achirale 4-hidroksiebensoksasole was gesintetiseer in goeie opbrengste. Hierdie verbindings was toe behandel met verskeie oorgangsmetale, waarvan slegs die Pdsoute enige bruikbare verbindings gevorm het. Die eerste strukturele bewyse van die binding van die 4-hidroksiebensoksasole is aangeteken met behulp van enkelkristal X-straaldiffraksie ontleding van die koördinasieverbindings wat gevorm is. Verskillende koördinasie mode is aangeteken, afhangende van die ligand en die Pd-sout wat gebruik was. Die PdCl2 verbindings is ook vir katalitiese aktiwiteit met 'n Heck reaksie getoets. Die reaksie het baie goeie omskakeling gewys vir die reaksie tussen iodobenseen en stireen na stilbeen. Verdere ondersoeke het getoon dat die ligande nie ‘n beduidende rol in die reaksie speel nie en die produkte moontlik slegs as gevolg van die PdCl2 se reaktiwiteit is. Gedurende hierdie tydperk was daar ook probeer om die fenol groep met P(III) groepe te funksionaliseer. Met die uitgangstowwe sou die koördinering en katalitiese studies herhaal word. Pogings om hierdie verbindings te sintetiseer was nie suksesvol nie, met oksidasie van die P(III) na P(V) groepe of afbreking van hierdie verbindings. Pogings om dit te sintetiseer via fosfor beskermingstegnieke, deur gebruik te maak van BH3 of die in situ vasvang van die verbindings met oorgangsmetale, was ook nie suksesvol nie. Gedurende die vasvang eksperimente het die fosfien en PdCl2 ‘n herrangskikkings-produk gevorm wat op sy eie ‘n bekende en nuttige katalisator is. Ten slotte was 'n klein biblioteek van chirale bensoksasole en 4-hidroksiebensoksasole gesintetiseer, vanaf aminosure. Om die ringsluiting te bewerkstellig was ‘n Mitsunobu reaksie gebruik. Antimikrobiese toetse met hierdie verbindings het nie enige noemenswaardige resultate opgelewer nie.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Modification of chitosan with benzoylisothiocyanate was attempted, however due to solvent problem the study was left incomplete till appropriate solvent is designed. N,N-diethyl-N -camphanoylthiourea (HL8), N-piperidyl-N '-camphanoylthiourea (HL9), N-pyrrolidyl-N -camphanoylthiourea (HL10) and N,N-diethyl-N -adamantylcarbonyl thiourea (HL11)have been synthesised and characterised for the first time. Two of these ligands HL8 and HL11, were used to form a number of transition metal complexes, namely H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2], translcis-[Zn(L 8_S,0)2], translcis-[Pt(L 8_S,0)2], Ag2[(HL8-S)(L-J.1-S,O)]2, translcis- [Ni(L11-S,O)2]and translcis-[Cu(L11_S,O)2]. The new products are fully characterised by means of MS, IR spectroscopy, NMR spectroscopy, elemental (C, H, Nand S) analysis and melting point determinations. The H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8- S,O)2], trans-[Cu(L8-S,O)2] and Ag2[(HL8-S)(L-J.1-S,O)]2 are also characterised by Xray diffraction analysis. The structure of the new chiral N,N-dialkyl-N' -camphanoylthiourea ligand (HL8) has a significant effect on its coordination chemistry with transition metal ions. This ligand forms H30+ {fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L-S,O)2] and Ag2[(HL8- S)(L8-J.1-S,O)]2 complexes with the Co(II), Ni(II), Cu(II) and Ag(I) metal ions respectively. The spectroscopic and X-ray diffraction results of these complexes indicate a bidentate mode of coordination of the ligand (with its Sand °donor atoms) to the Co(II), Ni(II) and Cu(II) metal ions. The reaction of this ligand with silver(I) however affords the formation of a binuclear silver(I) complex exhibiting monodentate and bidentate modes of coordination within the same complex. The exclusive formation of trans-[Cu(L8-S,0)2] is a new phenomenon for the HL type thiourea ligands with Sand °donor atoms. Up to this point a maximum of 15 % trans-isomer has been reported in ltterature." All the transition metal complexes made with HL8and HL11are air stable in both the liquid and solid states except the H30+{fae-[Co(L 8-S,Ob]} Interestingly the deep green fae- H30+{fae-[Co(L8-S,Obn complex is air sensitive and the Co(II) oxidizes to Co(III) in the complex by atmospheric O2. The oxidation of Co(II) to Co(III) in the complex is confirmed by 1Hand 13CNMR spectra as well as by UV-Visible spectra of the complex. The NMR spectra of the complexes indicated the presence of one isomer in each complex except for the NMR spectra of the platinum complex of the HL8 ligand. The presence of the minor trans-[Pt(L8-S,Q)21 isomer in combination with the major cis-[Pt(L8-S,Q)21 isomer in the platinum complex was indicated by the 1H, 13Cand 195ptNMR spectra of the complex. / AFRIKAANSE OPSOMMING: Pogings om chitosan met benzoylisothiocyanate te modifiseer is onvoltooid gelaat weens die gebrek aan'n geskikte oplosmiddel. N,N-diethyl-N -carnphanoylthiourea (HL8), N-piperidyl-N -camphanoylthiourea (HL9), N-pyrrolidyl-N -camphanoylthlourea (HL10) en N,N-diethyl-N -adamantylcarbonyl thiourea (HL11) is vir die eerste keer gesintetiseer en gekarakteriseer. Twee van die ligande, HL8 en HL11, is gebruik om verskeie oorgangsmetaalkomplekse te berei, nl. H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2], trans/cis-[Zn(L8 - S,0)2], trans/cis-[Pt(L8-S,0)2], Ag2[(HLB-S)(L-jl-S,0)]2, trans/cis-[Ni(L11-S,0)2] en trans/cis-[Cu(L11_S,0)2]. Die nuwe produkte is volledig gekarakteriseer deur middel van MS, IR spektroskopie, KMR spektrometrie, elemente (C, H, N en S) analise en smeltpuntbepaling. Die komplekse H30+{fao-[Co(L8-S,0)3n, cis-[Ni(L8-S,0)2], trans- [Cu(L8-S,0)2] en Ag2[(HLB-S)(L-jl-S,0)]2 is ook deur middel van X-straaldiffraksieanalise gekarakteriseer. Die struktuur van die nuwe chirale N,N-dialkyl-N'-camphanoylthiourea ligand (HL8) het In beduidende invloed op die koordinasie van hierdie ligand met oorgangsmetaalione. Die ligand vorm H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2], trans-[Cu(L-S,0)2] en Ag2[(HL8-S)(L8-Il-S,0)]2 komplekse met Co(ll)-, Ni(II)-, Cu(II)- en Ag(I)-ione respektiewelik. Spektroskopiese en X-straaldiffraksie-analise van die komplekse toon dat die ligande op 'n bidentate wyse d.m.v. die S- en O-donoratome met Co(II), Ni(lI) en Cu(lI) koordineer. Die reaksie van hierdie ligand met Ag(I)-ione lei egter tot die vorming van 'n dikernige silwer(I)-kompleks waarin die ligande monodentaat (S) en bidentaat (S en 0) aan die metaal gebind is. Die vorming van uitsluitlik die trans-[Cu(L8-S,0)2] in die reaksie van HL8 met Cu(lI) is 'n besondere fenomeen in die chemie van hierdie tipe ligande; in die literatuur word melding gemaak van slegs een ander trans-kompleks met hierdie ligande, en dan wel met 'n maksimum opbrengs van 15%.29 Alle oorgangsmetaalkomplekse met HLB en HL11 is stabiel indien blootgestel aan lug, ongeag of die verbindings opgelos word of in die vastetoestand verkeer, behalwe H30+{fao-[Co(L8-S,Ohn. Die diep-groen gekleurde H30+{fao-[Co(L8-S,Ohn)3]} kompleks is lugsensitief; Co(lI) word deur lugsuurstof na Co(lIl) ge-oksideer. Die oksidasie in die kompleks kan deur middel van 1H en 13CKMR spektrometrie sowel as UV-sigbare spektrofotometrie bevestig word. Die KMR spektra van alle komplekse dui op die teenwoordigheid van slegs een isomeer in oplossing, behalwe in die geval van die platinum(lI) kompleks met HL8. Die teenwoordigheid van lae konsentrasies trans-[Pt(L8-S,0)2] isomeer tesame met veel hoër konsentrasies van die cis-[Pt(L8 -S,O)2] isomeer word deur 1H, 13Cen 195ptKMR spektroskopie aangedui.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Microbiology / Doctoral / Doctor of Philosophy