This dissertation is a study of two major topics that involve synthetic strategies for new classes of phosphorescent gold(I)-based metallodendrimers. The phosphorescence of organic and inorganic luminophores originates from spin-orbit coupling owing to internal or external heavy atom effects as well as metal-centered emissions. Previous work in the Omary group entailed systematically designed small molecules, metallopolymers, and unconjugated metallodendrimers that contain d10 and d8 metals, whereas this dissertation aims in part to expand such strategies to the conjugated metallodendrimer regime. In one approach novel synthetic strategies were used to make first-generation phenyl acetylene dendrimers and phosphine derivatives thereof. The phosphine dendrimers are made by tethering one of the phosphines to an unsaturated dendrimer, as such phosphine dendrimers are better chromophores and luminophores due to their structural rigidity and extended conjugation. In another approach, 2- and 3-coordinate Au(I) dendritic complexes are synthesized from these phosphine dendrimers. This study is further extended to study metallodendritic complexes with different cores, for example triphenylene-based metallodendritic complexes with six acetylene branches. The physical properties of the metallodendrimers can be modulated upon proceeding to further dendrimer generations or by using solubilizing groups on the peripheral phosphines, thus allowing better processability for thin-film fabrication as required for molecular electronic devices and higher chance for crystal growth toward accurate structural characterization. Other data produced in this project suggested that some structural alterations led to porous solids that render them suitable for realized and potential applications in energy storage and carbon capture. The interesting luminescence properties of the metallodendrimers and porous extended solids produced in this dissertation are significant toward utilizing such materials for optoelectronic applications such as energy-saving organic light-emitting diodes and optical sensors for environmental pollutants.

Les métallodendrimères sont des macromolécules précises contenant des centres métalliques dont les propriétés sont exploitables pour la fabrication de nanodevices utiles en catalyse, reconnaissance moléculaire et en tant que précurseurs de nanoparticules. Pour leur contruction, de nouvelles réactions ont été mises au point à partir d’alcynes organométalliques électrophiles qui ont permis la formation de liaisons C-C, C-N et M=C, mettant en jeu des métallocènes du fer, du ruthénium et du cobalt. Cette ingéniérie moléculaire a conduit à de nouvelles métallo-étoiles, dendrimères et nanoparticules d’or aux propriéties rédox originales. / Metallodendrimers are precise macromolecules containing metallic centers with properties that are exploitable for nanodevice fabrication providing uses in catalysis, molecular recognition and as nanoparticle precursors. For their construction, new reactions have been disclosed from electrophilic organometallic alkynes leading to the formation of C-C, C-N and C=C bonds that involve iron, ruthenium and cobalt metallocenes. This molecular engineering has produced new metallo-stars, metallodendrimers and gold nanoparticles with original redox properties.

>Magister Scientiae - MSc / The tuberculosis (TB) disease to this day remains one of the world’s prominent killerdiseases. Pyrazinamide (PZA) is one of the most commonly prescribed anti- tuberculosis (anti-TB) drugs due to its ability to significantly shorten the TB treatment period from the former nine months to the current six months duration. However, excess PZA in the body causes hepatotoxicity and damages the liver. This hepatotoxicity, together with the resistance of the bacteria to treatment drugs, poor medication and inappropriate dosing, greatly contribute to the high incidents of TB deaths and diseases that are due to side effects (such as liver damage). This brings about the calls for alternative methods for ensuring reliable dosing of the drug, which will be specific from person to person due to inter-individual differences in drug metabolism. A novel biosensor system for monitoring the metabolism of PZA was prepared with a Ni-PPI-PPy star copolymer and cytochrome P450 2E1 (CYP2E1) deposited onto a platinum electrode. The nanobiosensor system exhibited enhanced electro-activity that is attributed to the catalytic effect of the incorporated star copolymer. The biosensor had a sensitivity of 0.142 µA.nM-1, and a dynamic linear range (DLR) of 0.01 nM-0.12 nM (1.231 – 7.386 ng/L PZA). The limit of detection of the biosensor was found to be 0.00114 nM (0.14 ng/L) PZA. From the HPLC peakconcentration (Cmax) of PZA determined 2 h after drug intake is 2.79 – 3.22 ng.L-1,which is very detectable with the nanobiosensor as it falls within the dynamic linear range.

Thesis (PhD)--University of Stellenbosch, 2011. / In this thesis we describe the application of novel salicylaldimine and iminopyridyl nickel metallodendrimer complexes as catalysts in the transformation of á-olefins as well as in the polymerization of norbornene. New cyclic dendrimers based on cyclam as a core (L1-L8) were synthesized and characterized via FTIR and NMR spectroscopy, mass spectrometry and microanalysis. Subsequently the generation 1 cyclam-based dendrimers as well as the commercial generation 1 to generation 3 DAB-PPI dendrimers were functionalized with salicylaldimine and iminopyridyl moieties on the periphery to produce new ligands, DL1-DL10. These modified dendritic ligands were subsequently complexed to Ni salts to obtain the metallodendrimer complexes, C1-C8. The metallodendrimers were characterized by FTIR spectroscopy, mass spectrometry, microanalysis, magnetic susceptibility measurements, UV-Vis spectroscopy and thermal gravimetrical analysis (TGA). The DAB G1-G3 salicylaldimine ligands (DL1-DL3) were subjected to computational studies and the optimized structures were obtained by density functional theory (DFT) calculations. The effect of the increase in dendrimer generation on the structural arrangement of the dendrimer was also investigated. The following aspects were probed using molecular modeling: a) the possible coordination site for the Ni to the first generation dendrimer ligand, DL1, and b) the optimized structure of the first generation salicylaldimine nickel complex, C1. We subsequently evaluated catalysts, C1-C7, in the vinyl polymerization of norbornene, using methylaluminoxane (MAO) as a co-catalyst. All the catalysts were found to be active for norbornene polymerization with the weight of the polymers obtained ranging from 5.12 x 105 - 11.17 x 106 g/mol. The DAB-based iminopyridyl catalysts (C4-C6) exhibited higher activities than its analogous salicylaldimine catalysts (C1-C3) under the same reaction conditions. Also, the cyclam-based salicylaldimine nickel catalyst (C7) exhibited higher activities than the DAB-based salicylaldimine nickel catalyst, C1. A negative dendritic effect was observed for the G1-G3 DAB salicylaldimine catalysts since the optimum activity for the G3 catalyst, C3, was lower than that for the G2 catalyst, C2. These nickel complexes were also evaluated as ethylene oligomerization catalysts and were found to produce a range of ethylene oligomers (C4-C18) as well as some longer chained oligomers, when employing EtAlCl2 as a co-catalyst. We observed however that the free EtAlCl2 mediates the Friedel-Crafts alkylation of the solvent, toluene, in the presence of the obtained ethylene oligomers to give uneven carbon number products, which are mixtures of alkylated benzenes. Our metallodendrimer catalysts also isomerized and in some cases dimerized 1-pentene. In both ethylene oligomerization and 1-pentene isomerization processes, the salicylaldimine catalysts exhibited higher activity towards olefin transformation than the iminopyridyl catalysts. The cyclam-cored dendrimer catalyst again showed the highest activity. From the results obtained thus far it can be concluded that these nickel metallodendrimers exhibit great potential as catalysts in the transformation of unsaturated hydrocarbons.