A series of fluorinated LiCoO2 compounds, LiCoO2−xFx with x = 0.05 − 0.65, were synthesised by both a sol-gel and a solid-state method. The sol-gel method utilises LiNO3 and Co(NO3)2.6H2O as Li and Co sources respectively, water and 1-butanol as solvent for the fluoride precursor LiF, and citric acid as the chelating agent. The prepared materials were compared using pXRD, SEM, Raman, TG and DTA analyses. pXRD revealed a secondary phase appearing at x= 0.25 in materials prepared by the sol-gel method and as early as x= 0.08 in materials prepared by the thermal solid-state method. Materials prepared by the thermal solid-state method required higher temperatures and longer times than materials prepared by the sol-gel method. The results showed that more fluorine can be incorporated in the LiCoO2 structure by the sol-gel than the solid-state method. The secondary phase was identified as lithium oxydifluoride, LiCoOF2. Relatively pure material with stoichiometry could be prepared by both methods. The space was determined as either 𝐶2 or 𝑃1 and the unit cell dimensions for the two alternatives are reported. This secondary phase has been reported in the literature, but had not been positively identified at the time of submission of this dissertation. Keywords: fluorinated LiCoO2; LiCoO2−xFx; sol-gel fluorination; solid-state fluorination; lithium oxydifluoride. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

Corrosion is one of the most expensive failures in industries that used metal components and other construction materials. In fact, corrosion is responsible for hundreds of billions-dollar loss in the US alone each year. In general, corrosion occurs when metal surfaces are exposed to water, oxygen, acids, bases, or salts. Therefore, metal substrates must be protected by using materials that act as barriers to avoid destructive corrosion attack. Aluminum is one of the most common metals used in the industry; and it is used in many places such as refining and petroleum production equipment, pipelines, and fossil fuel power plants. Aluminum is known to have corrosion resistance due to the forming of an oxide layer that can be reformed rapidly if the surface gets damaged. However, in the long-term the oxide layer cannot protect the aluminum surface from corrosion because it is stable only in neutral mediums and it is soluble in acidic and basic environments. Barrier protection is one of the most effective methods that prevent aluminum surfaces from being exposed to corrosive environments. These barriers can be organic or inorganic coatings that can limit the electron transport or the cathodic and the anodic reactions between aluminum alloys and the surrounding environment. Fluorinated polymers that were used in this study exhibit excellent properties which make them good candidates for corrosion protection applications. These properties include high hydrophobicity which is responsible for repelling oxygen and water and reducing the wettability of the metal surface, strong adhesion to the metal surface allowed for covering and protection of substrates in aggressive environments, and thermal stability that allows for using these polymers in high temperature environments. Overall, the corrosion protection, which was evaluated using electrochemical techniques, and the mechanical properties were improved with these fluorinated polymeric coatings in comparison to the bare aluminum alloys which proves to be advantageous for using these polymeric coatings in many areas including marine environments, oil and gas industries, and fossil fuel power plants.

Dichapetalum cymosum (poison leaf) is a very common problem plant in southern Africa. Fluoroacetic acid, believed to be the poisonous entity in the plant, is produced by the plant, but the micro-organisms associated with this plant may also play a role in the production thereof. A previous study on Burolderia cepacia, an endophyte of D. cymosum showed active metabolism of fluoroacetate by this endophyte. The isolated endophytes from D. cymosum were studied to determine whether they synthesise any fluorinated compounds. It seemed from preliminary results that symbionts might play a role in the synthesis of the poisonous entities in D. cymosum, but further investigation is required. The detection of glandular lesions on the abaxial side of the leaf led to closer examination and the cross sections revealed unusually deformed epidermis cells with adjacent cells containing vacuoles filled with phenolic-like crystals. Transmission electron microscopy (TEM) of the spongy parenchyma cells directly above the glandular lesions indicated the presence of clusters of small, virus-like particles (VLPs) in the chloroplasts. Observations by TEM showed that these VLPs have analogous structures to phytoferritin. Tapura fischeri (leafberry tree) is a tree member of the same family, and it was found to also contain a fluorinated compound. Endophytes were also found in the plant and similar glandular lesions with analogous VLPs were observed at these sites. This might indicate that endophytes have a share in the biosynthesis of the fluorinated compounds found in Dichapetalaceae. Numerous factors ought to be considered in order to fully understand the chemical ecology of the intricate system regarding the endophytes and the possible toxicity of the family Dichapetalaceae. / Dissertation (MSc)--University of Pretoria, 2012. / Plant Science / unrestricted

This thesis deals with the synthesis of prodrugs based on analogs of nucleoside phosphonates derived from 6-fluoro-3-hydroxypyrazine-2-carboxamide (T-705) and 3- hydroxypyrazine-2-carboxamide (T-1105). T-705 and T-1105 act as inhibitors of an influenza RNA polymerase. Both compounds mimic naturally occurring nucleobases, so their fluorinated nucleoside phosphonates could also be biologically active. Derivatives of 2-deoxy-2-fluoro-D-ribose (2-FdR) were prepared in this work. Because of complications during the syntthesis of 3-deoxy-3-fluoro-D-ribose (3-FdR) derivatives, 5- deoxy-5-fluoro-D-xylose (5-FdX) derivatives were prepared instead. Deoxyfluorination was done after incorporation of suitable protecting groups followed by selective deprotection and phosphonate binding. Furthermore nucleosides were synthetised using silyl-Hilbert-Johnson method and their bis-POM derivattives were also prepared. Key words: favipiravir (T-705), T-1105, prodrugs, phosphonates, fluorinated nucleosides

Herein, a series of tin and oxidovanadium complexes, as well as a hexanuclear manganese cluster, supported by the bidentate, dianionic perfluoropinacolate (pinF) ligand, {(O(C(CF3)2)2}2−, are reported. While six-coordinate SnIV-pinF complexes (2.1−2.3) were found to be spectroscopically similar to SnO2 (cassiterite), four-coordinate SnII-pinF complexes (2.4−2.5) possess low 119Sn NMR chemical shifts and remarkably high quadrupolar splitting. Additionally, the Sn(II) complexes are unusually unreactive towards both Lewis acids and bases. Computational analysis suggests that this lack of reactivity with Lewis acids arises from the energetic inaccessibility of the HOMO (5s), and the lack of reactivity with Lewis bases is due to donation into the LUMO (5px) by fluorine atoms on the ligand. Furthermore, monomeric and dimeric {VIV=O}- and {VV=O}-pinF complexes (3.1−3.4) were synthesized and characterized, including (Me4N)2[V2(O)2(μ-O)2(pinF)2] (3.3a). Complex 3.3a was found to catalyze the oxidation of several benzyl alcohols at room-temperature under ambient conditions, reproducing reactivity known for VOx surfaces and demonstrating the thermodynamically challenging selective oxidation of alcohols to aldehydes/ketones. Finally, a hexanuclear manganese cluster, {MnIII4MnIV2(pinF)6(OK(THF))4(OH)4}, abbreviated {Mn6} (4.1) which contains four-fold axial symmetry, and its oxidized analog {MnIII3MnIV3(pinF)6(OK(THF))4(OH)4}[PF6] (4.2), were prepared and characterized. High-field EPR measurements of 4.1 confirm a high spin magnetic ground state of ST = 11, corroborating the oxidation state assignments of the manganese centers. While EPR and CTM data suggest the possibility of slow magnetic relaxation for 4.1, field-dependent SQUID magnetometry reveals a lack of magnetic hysteresis, precluding the SMM behavior hypothesized for 4.1.

This master thesis is dedicated to the preparation of fluorinated derivatives of carbocyclic nucleosides, that may serve as flaviviral replication inhibitors. Preparation of both monofluorinated as well as gem-difluorinated analogs of ribo and 2'-deoxyribonucleoside was attempted. While a suitable and reliable route for the preparation of monofluorinated compounds way found, synthesis of gem-difluorinated turned out to be rather challenging. Although most of the presented work dealt with compounds bearing adenine as a nucleobase, the universal applicability of the developed procedures, demonstrated on the preparation of a guanosine-type molecule, suggests that after slight optimization larger series of this type of compounds could be prepared.

Nous avons synthétisé des polymères possédant des terminaisons fluorées afin de formuler des nanocapsules comme agents de contraste ultrasonores (ACUs) pour l’imagerie des tumeurs. Ces nanocapsules sont composées d’un cœur de bromure de perfluorooctyle (PFOB), un liquide perfluoré biocompatible et échogène, et d’une coque polymère possédant trois blocs d’affinités différentes. Le bloc hydrophile de polyéthylène glycol (PEG) présent en surface des nanocapsules permet de prolonger leur temps de circulation dans le compartiment sanguin et de favoriser leur accumulation dans les tumeurs par l’effet de perméabilité et de rétention accrue. Le bloc hydrophobe de polylactide (PLA) permet de générer une coque dégradable plus stable que les membranes de lipides ou de tensioactifs qui composent les ACUs utilisés en clinique. Finalement, la terminaison fluorée permet de favoriser l’ancrage du polymère autour de la goutte de liquide perfluoré et d’augmenter l’échogénicité des nanocapsules. Deux stratégies différentes ont été développées pour introduire ce bloc fluoré. La première consistait à synthétiser un PLA terminé par un chaînon fluoré linéaire court (C3F7 à C13F27) et à le mélanger à un polymère dibloc PLA-PEG pour formuler les nanocapsules. Nous avons montré que l’efficacité d’encapsulation du PFOB augmente avec la longueur de chaîne fluorée jusqu’à C8F17. La deuxième stratégie consistait à synthétiser directement un polymère tribloc composé des trois parties PEG, PLA et fluorée sur la même chaîne, la partie fluorée étant constituée de 4 à 15 chaînons C8F17 pendants (structure en peigne). Des mesures de tension interfaciale ont montré que ces polymères triblocs s’adsorbent à l’interface PFOB/solvant organique et encapsulent le PFOB plus efficacement que le PLA-PEG non fluoré. La morphologie des capsules est fortement influencée par le nombre de chaînons fluorés présents dans le polymère et par la quantité de polymère utilisée lors de la formulation. Une masse élevée du polymère contenant 15 chaînons fluorés favorisera ainsi la formation de nanocapsules possédant plusieurs cœurs de PFOB. La diminution de la quantité de polymère fluoré a finalement permis de produire des capsules avec un seul cœur, une coque fine, et de forme légèrement ellipsoïdale. Ces capsules diffusent les ultrasons plus efficacement que les capsules de PLA-PEG non fluoré. Alors que la présence de chaînes de PEG atténue considérablement la réponse acoustique des capsules, l’addition des chaînons fluorés permet de contrebalancer cet effet. Cette amélioration provient de plusieurs paramètres : l’augmentation de la quantité de PFOB encapsulé, l’augmentation de la densité de la capsule, et la diminution de l’épaisseur de la coque des capsules. Par ailleurs, les polymères fluorés et leurs produits de dégradation n’induisent pas de cytotoxicité in vitro comparé à leurs analogues non fluorés. Ces nanocapsules apparaissent donc comme des agents de contraste prometteurs pour permettre de mieux visualiser les tumeurs par échographie. / We have synthesized polymers with fluorinated end chains to formulate nanocapsules as ultrasound contrast agents (UCAs) for tumor imaging. These nanocapsules are composed of a core of perfluorooctyl bromide (PFOB), a biocompatible and echogenic perfluorinated liquid, and a polymeric shell made of three blocks of different affinities. The hydrophilic block of poly(ethylene glycol) (PEG) at the surface of the nanocapsules allows increasing their circulation time in the blood and promoting their accumulation into tumors by the enhanced permeation and retention effect. The hydrophobic block of polylactide (PLA) allows generating a degradable shell with higher stability as compared to the surfactant- and lipid-based membranes of commercialized UCAs. Finally, the fluorinated block favors the wetting of the polymer around the perfluorinated liquid and improves the nanocapsules echogenicity. Two different strategies have been developed to introduce this fluorinated part. The first one consisted in synthesizing a PLA terminated by a short linear fluorinated chain (from C3F7 to C13F27) and mixing it with a PLA-PEG diblock polymer to formulate the nanocapsules. The encapsulation efficiency of PFOB was found to increase with the fluorinated chain length up to C8F17. The second strategy consisted in synthesizing directly a triblock polymer composed of the three parts (PEG, PLA and fluorinated) on the same chain, the fluorinated part consisting of 4 to 15 pendant C8F17 chains (with a comb-like structure). Interfacial tension measurements showed that these triblock polymers adsorb at the PFOB/organic solvent interface and encapsulate PFOB more efficiently than non-fluorinated PLA-PEG. The capsules morphology was strongly influenced by the number of fluorinated chains and the amount of polymer used for formulation. Formulation with a high quantity of the polymer containing 15 fluorinated pendants thus favored the formation of nanocapsules with several PFOB cores. Decreasing the fluorinated polymer quantity then allowed producing capsules with a single core, a thin shell, and a slightly ellipsoidal shape. These capsules were more efficient ultrasound scatterers than non-fluorinated PLA-PEG capsules. While the presence of PEG chains considerably attenuates the capsules acoustic response, addition of fluorinated chains seems to counterbalance this effect. Such improvement arises from several contributions: a higher encapsulated PFOB content, a higher density due to the presence of fluorinated chains, and a lower shell thickness. Furthermore, the fluorinated polymers and their degradation products did not induce any in vitro cytotoxicity as compared to their non-fluorinated analogues. These nanocapsules therefore appear as promising UCAs for tumor imaging.

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第24442号 / 理博第4941号 / 新制||理||1706(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)准教授 板東 俊和, 教授 深井 周也, 教授 秋山 芳展 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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