This thesis focuses on the construction of individual isomers of the R-CHF-CHF-CHF-R’ motif. The multi-vicinal fluorine motif is new in organic chemistry and therefore stereoselective methods giving rapid access to these motifs and with flexibility need to be explored. The research in the thesis succeeded in the preparation of (2S,3R,4S)-314 and (2S,3S,4R)-328. In Chapter 1, an overview of the impact of fluorine in organic molecules is given. Recent developments in asymmetric electrophilic and nucleophilic fluorination are described, as well as the preparation of multivicinal fluoroalkane motifs. Aldol reactions of either (R)- or (S)-N-(α-fluoropropyl)-2-oxazolidinones, mediated by TiCl 4 are reported in Chapter 2. Such aldol reactions gave rise to identical α-fluoro-β-hydroxy- aldol products with high diastereoselectivities (95% dr). After removal from the auxiliary α- fluoro-β-hydroxy- products were converted to the corresponding α,β-difluoro products. The synthesis of non symmetric vicinal trifluoro motifs (2S,3R,4S)-314 and (2S,3S,4R)-328 is described in Chapter 3. They were prepared by direct fluorination in three steps of the corresponding (2R,3R,4R)-erythro and (2R,3S,4S)-threo enantio-enriched epoxy-alcohols. The two erythro and threo epoxy-alcohol isomers behave very differently during the first fluorination step and then an attempt to study and rationalise this difference in behaviour is made.

Thesis (Ph.D.) - University of St Andrews, June 2008.

No description available.

M.S.

No description available.

This thesis focuses on studies investigating the structure of intermediates involved in fluorometabolite biosynthesis, and the potential applications of the fluorinase enzyme in positron emission tomography (PET). Chapter 1 introduces the rare natural occurrence of fluorinated compounds. The bacterium Streptomyces cattleya is known to biosynthesise two fluorinated secondary metabolites: the toxin fluoroacetate (FAc) and the antibiotic 4-fluorothreonine (4-FT). The enzymes and intermediates identified on this fluorometabolite biosynthetic pathway in S. cattleya, prior to this research, are discussed in detail. Chapter 2 presents studies towards the unambiguous structural identification of (3R,4S)-5- deoxy-5-fluoro-D-ribulose-1-phosphate (5-FRulP) as the third fluorinated intermediate on the biosynthetic pathway to fluoroacetate and 4-fluorothreonine in S. cattleya. Chapter 3 describes the synthetic routes to key molecules, necessary as reference compounds and substrates, to underpin the subsequent studies in this thesis. In particular, synthetic routes to 5'-deoxy-5'-fluoroadenosine (5'-FDA), 5'-deoxy-5'-fluoroinosine (5'-FDI), 5-deoxy-5-fluoro-D-ribose (5-FDR) and 5-deoxy-5-fluoro-D-xylose (5-FDX) are described. Chapter 4 describes the use of the fluorinase enzyme from S. cattleya as a tool for the synthesis of new [¹⁸F]-labelled sugars with potential application in positron emission tomography (PET). A new route to 5-deoxy-5-[¹⁸F]fluoro-D-ribose ([¹⁸F]FDR) is developed in a two-step enzymatic synthesis. A total of three potential radiotracers ([¹⁸F]FDA, [¹⁸F]FDR and [¹⁸F]FDI) are synthesised using fluorinase-coupled enzyme reactions. In addition, in vitro studies are reported with these [¹⁸F]-labelled sugars to investigate their uptake and potential as PET radiotracers in cancer cells. A preliminary rat imaging study with [¹⁸F]FDA is reported. Chapter 5 details the experimental procedures for the compounds synthesised in this research and the biological procedures for chemo-enzymatic syntheses and protein purification.

Lai, Kwing To = 鐵基超導體的合成與分析 : 氟及釔合摻SmFeAsO / 黎烱韜. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Lai, Kwing To = Tie ji chao dao ti de he cheng yu fen xi : fu ji yi he shan SmFeAsO / Li Jiongtao. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.v / Table of contents --- p.vii / List of table captions --- p.x / List of figure captions --- p.xi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Superconductivity --- p.1 / Chapter 1.1.1 --- Physical properties --- p.3 / Chapter 1.1.1.1 --- Zero resistance --- p.3 / Chapter 1.1.1.2 --- Meissner effect --- p.4 / Chapter 1.1.1.3 --- Josephson effect --- p.5 / Chapter 1.1.2 --- Type I and II superconductivity --- p.7 / Chapter 1.2 --- Iron-based superconductors --- p.7 / Chapter 1.2.1 --- Classifications and structures --- p.8 / Chapter 1.2.2 --- Physical properties --- p.12 / Chapter 1.2.3 --- Iron-based superconductors versus Cuprate superconductors --- p.13 / Chapter 1.2.4 --- Correlation between high-Tc superconductivity and magnetism --- p.14 / Chapter 1.2.5 --- Quantum phase transition by doping --- p.16 / Chapter 1.2.6 --- Sample preparation of undoped and doped iron-based superconductors --- p.17 / Chapter 1.3 --- Objectives of this research project --- p.18 / References --- p.20 / Chapter Chapter 2 --- Literature Review --- p.22 / Chapter 2.1 --- Theories of superconductivity --- p.22 / Chapter 2.1.1 --- London equation --- p.22 / Chapter 2.1.2 --- Ginzburg-Landau theory --- p.24 / Chapter 2.1.2.1 --- Mean-field theory and Landau theory --- p.24 / Chapter 2.1.2.2 --- Spatial varying order parameter and Gauge symmetry --- p.27 / Chapter 2.1.2.3 --- Applications --- p.31 / Chapter 2.1.3 --- BCS theory --- p.35 / Chapter 2.2 --- Magnetism in condensed matters --- p.39 / Chapter 2.2.1 --- Ferromagnetism and Antiferromagnetism from local moments --- p.40 / Chapter 2.2.1.1 --- Mathematical explanation in the mean-field approach --- p.40 / Chapter 2.2.1.2 --- Exchange interaction --- p.43 / Chapter 2.2.2 --- Antiferromagnetism in magnetic metals: Spin density wave --- p.45 / References --- p.52 / Chapter Chapter 3 --- Methodology and Instrumentation --- p.53 / Chapter 3.1 --- Sample preparation --- p.53 / Chapter 3.2 --- Characterization --- p.55 / Chapter 3.2.1 --- Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) --- p.55 / Chapter 3.2.2 --- Transmission electron microscopy (TEM) and Electron diffraction --- p.55 / Chapter 3.2.3 --- X-ray diffraction (XRD) --- p.56 / Chapter 3.2.4 --- X-ray photoelectron spectroscopy (XPS) --- p.57 / Chapter 3.2.5 --- Physical properties measuring system (PPMS) --- p.58 / Chapter 3.2.5.1 --- Transport properties --- p.58 / Chapter 3.2.5.2 --- Magnetic properties --- p.60 / Chapter 3.2.6 --- Raman spectroscopy --- p.62 / Chapter 3.3 --- Precautions --- p.62 / References --- p.63 / Chapter Chapter 4 --- Results --- p.64 / Chapter 4.1 --- Fluorine-doped SmFeAsO --- p.64 / Chapter 4.1.1 --- Morphologies and microstructures --- p.67 / Chapter 4.1.2 --- Phase and composition --- p.69 / Chapter 4.1.3 --- Lattice constants --- p.72 / Chapter 4.1.4 --- Transport properties --- p.73 / Chapter 4.1.5 --- Magnetic properties --- p.74 / Chapter 4.2 --- Fluorine and Yttrium co-doped SmFeAsO --- p.78 / Chapter 4.2.1 --- Morphologies and microstructures --- p.79 / Chapter 4.2.2 --- Phase and composition --- p.82 / Chapter 4.2.3 --- Lattice constants --- p.84 / Chapter 4.2.4 --- Oxidation state --- p.85 / Chapter 4.2.5 --- Transport properties --- p.88 / Chapter 4.2.6 --- Magnetic properties --- p.89 / Chapter 4.3 --- Quality control of the superconducting products --- p.94 / Chapter 4.3.1 --- Intermediate product SmAs --- p.95 / Chapter 4.3.2 --- Intermediate product FeAs --- p.104 / Chapter 4.3.3 --- Effects of annealing temperature --- p.110 / Chapter 4.4 --- Summary --- p.112 / References --- p.112 / Chapter Chapter 5 --- Discussions --- p.113 / Chapter 5.1 --- Effects of F doping --- p.113 / Chapter 5.2 --- Effects of YF doping --- p.115 / Chapter 5.3 --- Improvements in the quality of the superconducting samples --- p.117 / Chapter 5.4 --- Summary --- p.124 / References --- p.125 / Chapter Chapter 6 --- Conclusions and Suggestions for Future work --- p.126 / Chapter 6.1 --- Conclusions --- p.'126 / Chapter 6.2 --- Suggestions for future work --- p.128 / References --- p.130 / Chapter Appendix A --- Sealing samples in small evacuated silica capsules for DTA measurements --- p.131 / Chapter Appendix B --- AC susceptibility measurement --- p.133 / Chapter Appendix C --- Suggested readings for beginners --- p.135 / Bibliography --- p.138

Fluorinated alkyl substances, which can be persistent, toxic, and bioaccumulative, have been quantitated in many densely populated and remote regions, including in air, surface waters, groundwater, and biota; however, little is known about their transport or behavior in the environment. Wastewater effluent is one of the principal routes for introducing environmental contaminants into aquatic environments. The partitioning behavior of fluorinated alkyl substances between aqueous and particulate phases is not well characterized; thus, sorption onto sludge can be a removal mechanism of fluorinated alkyl substances from the wastewater stream. This is another route into the environment if the biosolids are land-applied. In an attempt to analyze for the fluorinated alkyl substances in wastewater, known aqueous-film-forming-foam (AFFF)-laden groundwater sampled from 3 military bases was used to develop an assay using liquid chromatography (LC), electrospray ionization (ESI) tandem mass spectrometry (MS/MS). While working on the method development, fluorotelomer sulfonates were detected at Wurtsmith AFB, MI, and Tyndall AFB, FL, where total fluoroatkyl sulfonates ranged respectively from below quantitation (���0.60 ��g/L) to 182 ��g/L and from 1100 ��g/L to 14,600 ��g/L. The LC ESI-MS/MS method was modified to quantitate fluorinated alkyl sulfonates in wastewater by incorporating a htgh volume sample loop (500 ��L), which lowered detection and quantitation limits by at least a factor of 50. This method was applied to 24 h composites of influents and effluents collected from treatment plants distributed nationwide. Fluorinated alkyl substances were observed at all 10 plants sampled, and each wastewater treatment plant was found to have a unique distribution of fluorinated alkyl substances, despite similar treatment processes. In 9 out of the 10 plants sampled, at least one class of fluorinated alkyl substance exhibited significant increases in the effluent as compared to the influent levels. The high-volume-injection LC ESI-MS/MS method was also used to monitor the mass flows of perfluoroalkyl sulfonates and carboxylates through a municipal wastewater treatment plant for 10 d. The perfluoroalkyl carboxylates were overall removed by the wastewater treatment process (25-40% removal). Perfluoroalkyl sulfonates were found to increase significantly (~200%) in the final effluent, and the fluoroalkyl sulfonamide acetic acids were found to increase by approximately 500% throughout the sludge process. From this plant, significant quantities of fluorochemicals are discharged with treated wastewater and biosolids, indicating that wastewater treatment plants are point sources of fluorinated alkyl substances and must be considered when determining origins and behavior of fluorinated alkyl substances in the environment. / Graduation date: 2005

No description available.

Thesis (Ph. D.)--Rutgers University, 2010. / "Graduate Program in Chemistry and Chemical Biology." Includes bibliographical references.