The purpose of this research was to investigate the kinetics and mechanisms of the photocatalytic degradation of organic substances in the presence of anions (bromide and chloride), using titanium dioxide as a photocatalyst. Tris(hydroxymethyl)aminomethane (Tris) and methanol were the organic substances used as probes. Photocatalytic degradation of the probes produces formaldehyde through reaction with hydroxyl radicals at the surface of the photocatalyst. The product was quantified using a modified Hantzsch reaction and UV-Vis spectroscopy at the fixed wavelength 368 nm. It was found that having bromide present in the reaction mixture resulted in an increase in the rate of formation of formaldehyde from Tris, while it resulted in a decrease from methanol. Bromide on the surface of the photocatalyst reacts with the hydroxyl radicals to form reactive halogen species (RHS). This study proposes that the RHS Br2•- oxidises the probe into a cation radical, which initialises the probe degradation and the subsequent formation of formaldehyde. Conversion from hydroxyl radicals to RHS leads to a greater selectivity in formaldehyde production. Increased selectivity of attack towards electron-rich centres can explain the observed results with the different probes in this study. A linear combination expression of the total production of formaldehyde was developed, through which the X-factor, a ratio of the production of formaldehyde by RHS relative to the production of formaldehyde by hydroxyl radicals, was calculated. However, no realistic values were obtained when calculating the X-factor for different anion concentrations, thus indicating that factors other than competition kinetics affect the degradation. No conclusions could be drawn regarding the effect of chloride on the formation of formaldehyde from Tris and methanol, as the results were ambiguous. / Syftet med denna studie var att undersöka mekanismer och kinetik bakom fotokatalytisk nedbrytning av organiska molekyler i närvaro av anjoner (bromid och klorid), där titandioxid användes som fotokatalysator. Tris(hydroxymetyl)aminometan (Tris) och metanol var de organiska substanserna som studerades. Den fotokatalytiska nedbrytningen av proberna resulterar i formaldehyd via reaktion med hydroxylradikaler på fotokatalysatorns yta. Produkten kan sedan kvantifieras genom en modifierad version av Hantzsch-reaktionen följt av UV-Vis spektroskopi vid en fixerad våglängd på 368 nm. Studien kom fram till att närvaron av bromid i reaktionslösningen resulterade i en ökad produktionshastighet av formaldehyd från Tris, medan det resulterade i en minskning från metanol. Bromid på ytan av fotokatalysatorn reagerar med hydroxylradikaler och bildar reaktiva halogena molekyler (RHS). Denna studie föreslår att RHS:en Br2•- oxiderar proben till en radikalkatjon, som initierar nedbrytningen av proben och efterföljande bildning av formaldehyd. Omvandling från hydroxylradikaler till RHS leder till högre selektivitet av bildning av formaldehyd. Ökad selektivitet av attacker mot elektronrika center kan förklara de observerade resultaten med de olika proberna i denna studie. Ett linjärkombinationsuttryck av den totala produktionen av formaldehyd utvecklades, från vilket X-faktorn, ett förhållande av produktionen av formaldehyd via RHS relativt till produktionen av formaldehyd via hydroxylradikaler, kunde beräknas. Inga realistiska värden erhölls dock vid beräkningen av X-faktorn för olika anjonskoncentrationer, vilket indikerar att andra faktorer än konkurrenskinetik påverkar nedbrytningen. Inga slutsatser kunde dras gällande klorids effekt på bildningen av formaldehyd från Tris och metanol, då resultaten var tvetydiga.

The mass spectra of the compounds [Me 3 SiCH2 nSiCl 4 n (n=1-3) were studied in detail. MIKES and CID spectra were used in conjunction with the observance of metastable processes to develop consistent fragmentation schemes. Particular attention is drawn to the formation of charged and neutral species containing the silicon-carbon double bond, including 2-silaallene, under conditions of electron impact.

In an effort to produce the tetrahedrally coordinated, catalytically active zinc center, three families of tris(2-pyridyl)methanol derivatives were synthesized and characterized. Zinc binding studies revealed that the binding behaviors of the ligands depended on the steric and electronic properties of the substituents on the pyridyl rings, as well as the functional group on the tertiary alcohol. A novel tris-pyridyl macrocyclic receptor was synthesized. The receptor possesses both hydrogen bond donors and acceptors. NMR titration experiments revealed that the receptor simultaneously bound both ammonium cation and the counter anion. The counter anion significantly influences the association between the receptor and the ammonium cation. Chiral ditopic macrocycles, which enantioselectively bind chiral ammonium cations, have also been synthesized. Their enantioselective binding properties, as well as the ditopic recognition properties were investigated

The remarks on this subject stem from the conditions spatial works engender in the encounter with the viewer. The aim has been to provide the reader with a framework within which to place individual experiences of the works. The exhibition Spatial Works, to which this research paper is connected, exemplifies variations within spatial work. By organizing an exhibition around this context, the variations presented is fleshed out. The research preceding the exhibition has resulted in the development of a specific terminology; an articulation of different practices in installation art. Psychodramatic, Thespian, Temporal and Permutation are here seen as mannerisms of spatial works of art. The expanded significance presented in this paper is a feature of composition, as the dramatic condition characterizes the encounter between object and subject. The polyphony of information encountered by the viewer is not only created by the art work itself, but also by its signifying composition, so to say `al fresco´ of the work, of which the observer gains certainty of the pieces spatiality as well as understands of the work of art. / WIRE, Critical Writing and Curatorial Practice

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High spin has been shown to be necessary for optimal reactivity of transition metal complexes toward the activation and functionalization of C-H bonds. This thesis presents our examination of the weak-field, tripodal, trianionic tris(pyrrolyl)ethane (tpe) ligand and its complexes. Outer-sphere oxidation of the manganese, iron, cobalt, nickel and zinc complexes of tpe were performed by electrochemical and chemical methods. Electrochemical oxidation occurred at the same potential for each species, suggesting a ligand-based oxidation. The reaction product of chemical oxidation of iron showed oxidation of a pyrrole unit followed by H-atom abstraction to form a dichelated species. Density functional theory calculations confirm these results, and in silico oxidation of the complexes is entirely ligand-based. These results establish that tpe complexes are oxidized at the pyrrolide subunits in outersphere electron transfers, and elucidate minimal metal-ligand electronic communication. The more reactive \([(tpe)Fe(THF)]^−\) anion exhibits rapid binding of three equivalents of tert-butyl isonitrile, while reaction with excess carbon monoxide induces ligand fragmentation to form a species wherein two molecules of carbon monoxide have been reductively coupled. A mechanism based on the observed isonitrile species is proposed. The use of inner-sphere oxidant reagents allows for several stable iron (III) complexes of tpe to be isolated and characterized. Alkyl peroxides and alkyl disulfides, organic azides, and diphenyldiazomethane are all shown to oxidize iron by a single electron. Reaction with organic azides results in the formation of iron (III) amide species, likely as a result of Hatom abstraction. The weak-field of tpe creates a high propensity for forming high-spin iron (III) complexes, to the extent that diphenyldiazoalkane acts as a redox-active ligand and provides a one-electron reservoir to reveal a high-spin \(Fe^{3+}\). Spectroscopic and computational studies were undertaken to rigorously assign the physical oxidation state of iron in all cases. Given the outer-sphere redox liability of the tpe ligand, and the capability for inner-sphere oxidation local to iron, tpe complexes of iron represent a new class of metal-ligand redox activity, wherein the metal and ligand form two separate redox reservoirs, accessible via different mechanisms. / Chemistry and Chemical Biology

Deux nouveaux concepts, visant à reproduire la chimie radicalaire des diétains à l’aide de radicaux centrés sur le silicium, sont présentés à travers ce manuscrit. Le premier concept introduit les “silaboranes”, des molécules constituées d’un motif de type silane et d’un atome de bore. Ceux-ci ont pour la première fois été exploités comme générateurs de radicaux triméthylsilyle via l’utilisation de la réaction de SHi sur le silicium (Substitution Homolytique Intramoléculaire) à partir de disilanes. Des études cinétiques et de modélisation moléculaires de la réaction de SHi ont, entre autres, permis de rationaliser les résultats. Le potentiel des “silaboranes” en tant que substituts des diétains a été entrevu à travers des réactions d’additions radicalaires d’halogénures sur des éthers d’oxime sulfonylés. Le concept des "silaboranes" a ensuite été étendu à des hydrures de silicium, grâce à une réaction de transfert d’hydrogène intramoléculaire, permettant de produire des radicaux triphénylsilyles. Le second concept a révélé la capacité des allyl tris(triméthylsilyl)silanes pour reproduire les réactions radicalaires des diétains via une réaction de beta-fragmentation du groupement tris(triméthylsilyle). Ces substrats, source de radicaux tris(triméthysilyle) et simples d’accès, se sont avérés d’intéressants candidats pour assister l’addition de dérivés bromés et iodés sur des substrats sulfonylés de type allyl, vinyl et éther d’oxime. / Two new concepts, aiming to substitute ditin radical chemistry by using silyl radicals, are developed throughout this manuscript. The first concept introduces “silaboranes”, molecules made up of a silane unit and a boron atom. For the first time, the ability of these precursors to generate trimethylsilyl radicals was demonstrated by using the SHi reaction at silicon (Intramolecular Homolytic Substitution) from disilanes. Besides, results are supported by kinetic and computationnal studies of the SHi reaction at silicon. Capacity of “silaboranes” to achieve tin-free radical processes was demonstrated thanks to radical addition of halogenated species on sulfonyl oxime ethers. “Silaboranes” concept was then extended to silicon hydrides using intramolecular hydrogen transfer as source of triphenylsilyl radicals. The second concept highlights the ability of allyl tris(trimethylsilyl)silanes to make possible tin-free radical reactions via beta-fragmentation of the tris(trimethylsilyl) group. These compounds, source of tris(trimethylsilyl) radicals and easily available, open very interesting perspectives in tin-free radical addition of bromides and iodides species on sulfonyl derivatives as allyl sulfones, vinyl sulfones or sulfonyl oxime ethers.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-03T15:55:30Z No. of bitstreams: 1 angelinamariadealmeida.pdf: 27513122 bytes, checksum: 4a1c9bd4d957558435fb0e88c9c8bae9 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-13T13:36:53Z (GMT) No. of bitstreams: 1 angelinamariadealmeida.pdf: 27513122 bytes, checksum: 4a1c9bd4d957558435fb0e88c9c8bae9 (MD5) / Made available in DSpace on 2017-05-13T13:36:53Z (GMT). No. of bitstreams: 1 angelinamariadealmeida.pdf: 27513122 bytes, checksum: 4a1c9bd4d957558435fb0e88c9c8bae9 (MD5) Previous issue date: 2013-03-01 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho foram realizadas as sínteses de aminas e amidas aromáticas anfifílicas inéditas derivadas do Tris. A primeira série foi obtida através da reação de aminação redutiva de p- alquiloxibenzadeídos com o TRIS. A série das amidas foi obtida a partir do ácido p- alquiloxibenzóicos: esses foram convertidos a cloretos de acila e tratados com TRIS. As metodologias usadas foram simples e todos os compostos foram obtidos em rendimentos satisfatórios. Após purificação e caracterização através das técnicas espectroscópicas usuais (IV, RMN de ¹H e ¹³C e espectroscopia de massas). Os compostos sintetizados foram avaliados quanto as suas propriedades biológicas in vitro. A atividade antimicrobiana foi avaliada frente a bactérias Gram-positivas (ATCC e MRSA), bactérias Gram-negativas (ATCC) e fungos Candida. O potencial anti-inflamatório foi avaliado através da capacidade dos compostos de inibirem a produção de óxido nítrico por macrófagos ativados. A citotoxicidade foi investigada através do método do MTT. Os resultados obtidos mostraram que apenas as aminas foram ativas nos testes, com concentrações inibitórias mínimas comparáveis ou superiores as dos padrões usados como controle (cloranfenicol e itraconazol), e não apresentaram toxicidade nessas concentrações. Foi possível estabelecer uma boa correlação positiva entre a lipofilicidade dos compostos testados e a atividade antimicrobiana. Os estudos físico-químicos ainda estão em andamento com o intuito de estabelecer uma relação entre atividade biológica e propriedades surfactantes das novas aminas anfifílicas. / In this work were carried out the synthesis of novel amphiphilic aromatic amines and amides derived from Tris. The first set was obtained by reductive amination reaction of p- alkyloxybenzadehydes with TRIS. The series of amides was obtained starting from p- akyloxylbenzoic acid: these were converted to the acyl chlorides and treated with TRIS. The methodologies used were simple and all compounds were obtained in satisfactory yields. After purification and characterization through the usual spectroscopic techniques (IR, 1 H NMR, ¹³C NMR and mass spectroscopy), the synthesized compounds were evaluated for their biological properties in vitro. The antimicrobial activity was evaluated against Gram-positive bacteria (ATCC and MRSA), Gram-negative bacteria (ATCC) and fungi of Candida. The anti inflammatory potential was assessed by the ability of the compounds to inhibit nitric oxide production by activated macrophages. Cytotoxicity was assessed by the MTT method. The results showed that only the amines were active in the tests, with minimum inhibitory concentrations comparable or superior to the standards used as control (chloramphenicol and itraconazole), and showed no toxicity in these concentrations. It was possible to establish a good correlation between the lipophilicity of the tested compounds and the antimicrobial activity. The physico-chemical studies are still under going aiming to establish a relationship between the biological activity and the surfactant properties of the new amphiphilic amines.

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