Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 1992.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 280-300).

Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 307-320).

Hexanuclear transition metal clusters are a distinct class of chemical compounds that have some very interesting chemical and physical properties. Of recent interest in this field has been the [Re₆(μ₃-Se)₈]²⁺ cluster core. This Lewis acidic cluster core contains six substitutable coordination sites, and site differentiation can be accessed through protecting group ligands. The Lewis acidity has been shown to activate unsaturated cluster-bound ligands, and the expanded atom-like structure and high symmetry of the cluster core has potential use in synthesizing some fascinating and novel hybrid materials. Little work has been performed in establishing the scope of these chemical transformations. The work herein describes the efforts and successes of such work. Chapter 1 provides the essential background required for understanding the [Re₆(μ₃-Se)₈]²⁺ cluster core's synthesis, properties, and currently known research directions and successes. This chapter first introduces hexanuclear clusters in a general format, then focuses on the established catalytic and material capabilities that have been determined using this specific cluster core. Chapter 2 discusses the synthesis, characterization, and hydrogen-bonded assemblies formed from [Re₆(μ₃-Se)₈]²⁺ cluster-isonicotinic acid cluster complexes. These complexes have potential uses as hybrid inorganic/organic linkers for the generation of luminescent Lewis acidic metal-organic frameworks (MOFs). Prospective applications of such materials include catalysis, separations, and gas storage. Chapter 3 focuses on the novel chemistry of [Re₆(μ₃-Se)₈]²⁺ cluster-activated CH₃CN with N-based nucleophiles to form acetamidines. These ligands are of interest due to their use in medicinal chemistry, CO₂/CS₂ sequestration, and the formation of synthetically-relevant species. Quantitative yields are obtained and single-crystal XRD analyses reveal specific stereochemical outcomes. Trifluoroacetic acid (TFA) in a cluster-amidine CH₃CN solution removes the ligand as the acetamidinium TFA salt, and the starting cluster solvate is reproduced making a recyclable catalyst. Chapter 4 expands on a project similar to that of chapter 3, except that O-based nucleophiles are utilized for specific cluster isomers. The newly formed ligands, imino esters, are of interest in organic synthesis as valuable starting materials for the generation of β-lactams and heterocycles. ³¹P NMR and single–crystal XRD reveal Z stereochemistry is preferred in the cis isomer, but conflicting results for the hexasubstituted isomer leave stereochemical analyses unresolved. Chapter 5 attempts to incorporate the chemistry established in chapters 2-4 to provide some fresh and interesting research outlooks possible with the [Re₆(μ₃-Se)₈]²⁺ cluster core. Incorporation of the cluster into MOFs is discussed, and the possibility of post-synthetic modifications for metal sequestration, catalysis, and sensing is explained. Appendix A provides all the NMR data obtained for synthesized materials with peak picks and integrations provided. Appendix B entails all crystallographic information for structures determined after syntheses. Appendix C provide high-resolution mass spectra.

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Made available in DSpace on 2014-10-09T12:52:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:22Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Made available in DSpace on 2014-10-09T12:52:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:22Z (GMT). No. of bitstreams: 0 / O interesse pelo 188Re para aplicações terapêuticas na medicina nuclear é devido à meia-vida de 16,9 horas, emissão de partículas βֿ com energia máxima de 2,12 MeV e raios-γ de 155 keV adequados para a aquisição de imagens. O estudo apresenta a radiomarcação do HEDP (etidronato) com o 188Re eluído de geradores de 188W/188Re a base de Al2O3 e tipo-gel 188WZr. A dependência do rendimento do 188Re-HEDP na concentração do agente redutor, pH, tempo de reação, temperatura e adição de carregador Re2O7 foram avaliados. A partir das condições ótimas de marcação os rendimentos do 188Re-HEDP foram ≥ 98% tanto para os kits líquidos como liofilizados. A formulação padrão que representou esses resultados contém: 30 mg de HEDP, 7 mg de SnCl2, 3 mg de ácido ascórbico e adição de 20 μg de Re2O7. As reações foram conduzidas sob aquecimento de 100 °C por 30 minutos, seguidos de 60 minutos de incubação. Outro aspecto importante do trabalho foi o controle de qualidade radioquímico, comparando os resultados de CP, CCD e cromatografia iônica, além dos experimentos com a CLAE. A distribuição biológica realizada comprovou a captação pelo esqueleto e a estabilidade in vivo dos complexos de 188Re-HEDP. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP