Titan, le plus grand satellite de Saturne, possède une atmosphère dense, majoritairement composée d’azote (N_2) et de méthane (〖CH〗_4) et qui s’étend sur environ 1500 km d’altitude. L’interaction entre ces espèces et le rayonnement solaire ouvre la voie à des réactions de photodissociation et de photoionisation qui constituent le point de départ d’une croissance moléculaire très rapide et efficace dès les plus hautes couches de l’atmosphère. Cette croissance aboutie à la synthèse d’aérosols vers 1000 km d’altitude qui précipitent ensuite dans l’atmosphère.L’objectif de cette thèse est, de s’intéresser expérimentalement à l’interaction entre les espèces peuplant la haute atmosphère de Titan et le rayonnement solaire énergétique dans la gamme de l’UV sous vide (VUV), (longueur d’onde < 150 nm). Tout d’abord, nous avons étudié l’interaction avec les petites espèces chimiques neutres et majoritaires grâce à une nouvelle source VUV spécialement conçue pour cette thèse couplée au réacteur photochimique APSIS. Ce dispositif met en lumière la photochimie du système couplé azote-méthane, encore très mal connue.Ensuite, nous nous sommes penchés sur l’effet du VUV sur les aérosols formés dès les plus hautes couches, en photoionisant avec le rayonnement synchrotron de la ligne DESIRS des analogues de ces aérosols produits avec le dispositif PAMPRE. Cette méthode permet d’obtenir des informations sur leur photoionisation (seuil et section efficaces, spectres de photoélectrons) ainsi que sur leurs propriétés optiques. / Titan, Saturn's biggest satellite, possesses a dense atmosphere, mainly composed of nitrogen (N2) and methane (CH4), which goes up to 1500 km in altitude. The interaction between those chemical species and the solar light leads to some photodissociation and photoionization reactions that are the starting point of a fast and efficient molecular growth in the upper layers of the atmosphere. This growth ends with the synthesis of aerosols around an altitude of 1000 km that will then precipitate into the atmosphere.The aim of this thesis is to experimentally study the interaction between the species present in the upper atmosphere and the energetic solar radiations in the vacuum ultraviolet (VUV) range (wavelength below 150 nm). First, we looked at the interaction with the small, neutral and most abundant species thanks to a new VUV source specially designed for this thesis and coupled to photochemical reactor called APSIS. This new platform sheds some light on the photochemistry of a coupled nitrogen-methane system, which remains poorly understood.Then, we focused on the effects of the VUV light on the aerosols formed in the upper layers, by photoionizing, with synchrotron light from the DESIRS beamline, analogs of those aerosols produced on the PAMPRE platform. This method gives information about their photoionization (threshold and cross sections, photoelectron spectra) but also about their optical properties.

Este trabalho relata a síntese, caracterização e a investigação das propriedades fotoluminescentes dos complexos &#946;-dicetonatos (TTA = 2-tenoiltrifluoroacetonato e DBM =dibenzoilmetanato) de terras raras trivalentes (TR3+ = Sm3+, Eu3+ e Gd3+) com diferentes ligantes amidas. Os compostos sintetizados foram caracterizados através das técnicas de microanálises de C, H, e N, espectroscopia de absorção na região do infravermellio e UV-Vis, titulação complexométrica com EDTA, análises termogravimétricas TG/DTG e difratometria de raios-X (métodos do pó e monocristal). Para os ligantes sintetizados, além das duas primeiras técnicas, estes foram caracterizados por Ressonância Magnética Nuclear de próton e carbono 13 (RMN lH e 13C) as quais certificaram suas obtenções e purezas. Os dados de microanálises de CHN e titulação- complexométrica foram concordantes com as fórmulas gerais [TR(TTA)3L2] (exceto [TR(TTA)3(DMFA)(H2O)] e [TR(TTA)3(PZA)]) e [TR(DBM)3L], onde L é um ligante amida. Os espectros de absorção na região do infravermelho evidenciaram o caráter anidro da maioria dos complexos e que a coordenação dos &#946;-dicetonatos e amidas aos íons TR3+ ocorre através dos átomos de oxigênio dos grupos carbonila. As curvas TG/DTG corroboraram os dados dos espectros IV no que se refere à ausência de água coordenada aos íons metálicos (exceto nos complexos precursores e nos [TR(TTA)3(DMFA)(H<sub<2O)]). Os difratogramas de raios-X (método do pó) sugerem a existência de séries isomorfa para cada ligante amida. O complexo [Eu(DBM)3(DMAC)] foi obtido na forma de cristais e sua estrutura foi resolvida pelo método de difração de raios-X de monocristais. Os resultados mostraram que este complexo cristaliza no sistema triclínico, em grupo espacial P-l, com os seguintes parâmetros de cela: a = 10,30&#197;· b = 10,46&#197;·c = 22,67&#197; &#945; = 78,97°; &#946; = 78,58°; &#947; = 63,01°. A primeira esfera de coordenação é descrita como um prisma trigonal monoencapusado, onde sete átomos de oxigênio encontram-se coordenados ao íon Eu3+. As propriedades fotoluminescentes dos íons Sm3+ e Eu3+ nos complexos foram investigadas a partir dos espectros de excitação, emissão e curvas de decaimento de luminescência. Os espectros de emissão desses complexos mostraram, principalmente, bandas finas oriundas das transições intraconfiguracionais-4fN 4G5/2 &#8594; 6H5/2, 7/2, 9/2, 11/2 (Sm3+)e 5D0 &#8594; 7F0, 1, 2, 3,4 (Eu3+), dominados pelas transições hipersensíveis 4G5/2 &#8594; 6H9/2 (~645 nm) e 5D0 &#8594; 7F2 (~612 nm). Os desdobramentos dessas transições, de um modo geral, estão concordantes com um ambiente químico de baixa simetria ao redor do íon TR3+. Com base nos dados espectrais foram determinados os parâmetros de intensidade &#937;2 e &#937;4, os coeficientes de emissão radiativa (Arad) e não-radiativa (Anrad) e a eficiência quântica de emissão experimental do nível 5D0 do íon Eu3+ (&#951;). Os complexos de DBM apresentam maiores valores de &#937;2 do que aqueles com TTA, refletindo um ambiente químico mais polarizável com maior caráter covalente da ligação Eu3+-DBM. Os valores dos parâmetros experimentais (&#951;Sm e &#951;Eu) dos complexos de Sm3+ e Eu3+ apresentaram uma boa correlação, evidenciando que a polarizabilidade em tomo do íon Sm3+ é semelhante àquela nos complexos com o íon Eu3+. Observou-se que os valores de eficiência quântica do estado emissor 5D0 (&#951;) aumentam quando as moléculas de água são substituídas pelos ligantes amidas. Esses resultados são devidos a uma diminuição significativa dos processos não radiativos (Anrad) pela ausência dos supressores O-H nos complexos com ligantes amidas. No entanto, no caso do complexo com PZA, foi observado um valor de Anrad grande, sugerindo um forte acoplamento dos osciladores N-H com o estado excitado 5D0. Os valores altos de rendimentos quânticos experimentais, qa, da maioria dos complexos indicam que a transferência de energia Ligante-Eu3+ é muito eficiente. É importante salientar que o complexo [Eu(TTA)3(DMBZ)2] apresenta um dos maiores valores de rendimento quântico experimental ( q = 82 %) da literatura para compostos de coordenação com o íon Eu3+. Os processos de transferência de energia Ligante-Eu3+ foram investigados por modelos teóricos SMLC (Sparkle Model for Lanthanide Complexes). A estrutura do complexo [Eu(DBM)3(DMAC)] apresentou boa concordância com aquela determinada experimentalmente através da técnica de difração de raios-X. De um modo geral, o poliedro de coordenação ao redor do íon Eu3+ nas estruturas teóricas está, também, concordante com o desdobramento das bandas associadas às transições 5D0 &#8594; 7FJ. Os dados das taxas de transferência de energia determinados utilizando um conjunto apropriado de equações de taxa concordaram muito bem com os dados experimentais evidenciando a viabilidade do modelo teórico nos estudos de compostos de coordenação com íons terras raras trivalente. O comportamento fotoluminescente exibido pelos complexos de európio evidencia que este sistema atua como Sistemas Moleculares Conversores de Luz. / This work reports the synthesis, characterization and investigations of photoluminescent properties of &#946;-diketonate complexes (TTA = 2-thenoiltrifluoroacetonate and DBM = dibenzoylmethanate) of trivalent rare earths (TR3+ = Sm3+, Eu3+ e Gd3+) with different amide ligands. The synthesized compounds were characterized by the fol1owing techniques: microanalyses of C, H, and N, absorption spectroscopy in the infrared region and UV-Vis, complexometric titration with EDTA, thermogravimetric analyses TG/DTG and X-rays diffraction (powder and single crystal methods). In case of ligands, besides the two first techniques, they were also characterized by Magnetic Nuclear Resonance of proton and carbon 13 (MNR 1H and 13C) which were according with the expected results and indicated the higher purity degree of these ligands. The elemental analyses data of C, H, and N, and complexometric titration suggested the general formulas [TR(TTA)3L2] (except for [TR(TTA)3(DMFA)(H2O)] and [TR(TTA)3(PZA)]) and [TR(DBM)3L], where L is amide ligand. The infrared spectra indicated that the complexes are anhydrous and that the coordination of &#946;-diketonates and amides to the TR3+ ions occurs via oxygen atoms. TG/DTG curves corroborate with the IR data suggesting the absence of water molecules coordinated to the metal ions (except for the case of the precursors and [TR(TTA)3(DMFA)(H2O)] complexes). Besides, these curves indicated that the amide complexes show a higher thermal stability (~150 °C). The XRD diffractograms (powder method) suggest the presence of one isomorphic series for each amide ligand. The [Eu(DBM)3(DMAC)] complex was obtained in the single crystal form to obtain its structure by rays-X diffraction (single crystal method). The structural results showed that this complex crystallize in a triclinic system, as a spatial group P-1, with the following cell parameters: a = 10.30 &#197;; b = 10.46 &#197;; c = 22.67 &#197;; &#945; = 78.97 °; &#946; = 78.58 °; &#947 = 63.01 °. The first coordination sphere is described as a monocapped trigonal prism, with seven oxygen atoms bonded to the Eu3+ ion (six from the &#946;-diketonate chelate and one from amide ligand). The photoluminescent properties of the Sm3+ and Eu3+ -complexes were investigated by the excitation, emission and luminescent decay curves, recorded at room and liquid nitrogen temperatures. The emission spectra of the complexes displayed mainly the narrow bands arising from 4f-intraconfigurational transitions 4G5/2 &#8594; 6H5/2, 7/2, 9/2, 11/2 (Sm3+) and 5D0 >&#8594; 7F0, 1, 2, 3,4, (Eu3+), dominated by the hypersensitive bands due to the transitions 4G5/2 &#8594; 6H9/2 (~645 nm) and 5D0 &#8594; 7F2 (~612 nm), respectively. The splits of these transitions agree with the presence of a chemical environment with the low symmetry around the TR3+ ion. The intensity parameters (&#937;2 and &#937;4), the radiative (Arad) and non-radiative decay rates and the quantum emission efficiency of the 5D0 were obtained by the quantitative analyses of the emission spectra of the Eu3+ -complexes. The &#937;2 values were higher for the DBM than for the TTA-complexes, reflecting that the chemical environment are more polarizable around Eu3+ ion in the complexes with DBM, indicating the highest covalent character of the Eu3+ -DBM bond. It was observed that the &#951; values were increased when the water molecules were replaced by the amide ligands. These results reflect the decrease of the non-radiative rates (Anrad), which is a consequence of the absence of the O-H quenchers. However, it was observed that the complex with PZA ligand presents Anrad as high as that value in the hydrated complex, suggesting strong coupling of the N-H oscillators with the excited level. The experimental quantum yield, qa, of the complexes of europium ion in the solid state present a good correlations with the quantum emission efficiency, &#951;, indicated a very efficient energy transfer Ligand-to-Eu3+. It is important to notice, that the qa value for the [Eu(TTA)3(DMBZ)] (q = 82 %) complex is among the highest values reported in the literature for the coordination compound with Eu3+ ion. The energy transfer processes from ligand to metal were investigated by the theoretical models SMLC (Sparkle Model for the Calculation of Lanthanide Complexes). The theoretical structure of the complex [Eu(DBM)3(DMAC)] agrees with that one determined experimentally by X-ray diffraction. It was also observed that the coordination polyhedron around the Eu3+ ion (in the theoretical structures) corroborates with the split of the bands assigned to the 5D0 &#8594; 7FJ transitions. The energy transfer rates determined by the appropriated rate equations agree with the experimental quantum yield, suggesting the viability of theoretical model on studies of the trivalent rare earth coordination compounds The photoluminescent behavior exhibited by the europium complexes indicates that this system acts as Light Molecular Conversion Systems.

Entender o comportamento de filmes de petróleo na interface ar-água é crucial para lidar com derrames de petróleo e reduzir os consecutivos danos ao meio ambiente. Para tanto, filmes de Langmuir preparados com frações de petróleo tem sido normalmente estudados. Entretanto, as propriedades dos filmes preparados a partir de amostras de petróleo bruto podem diferir consideravelmente dos filmes preparados a partir das suas frações individuais. Filmes preparados na interface ar-água de diversas amostras de petróleo com composições distintas foram estudadas usando técnicas espectroscópicas e de superfície incluindo pressão superficial, potencial de superfície, BAM, fluorescência e MEV. Mostramos que petróleo forma um filme de Langmuir não homogêneo na interface ar-água. As isotermas de pressão superficial para os filmes de petróleo exibem as fases gás (G), líquido expandido (LE), líquido condensado (LC) e sólido (S) com quase nenhuma histerese nos ciclos de compressão e descompressão, ao contrário da grande histerese observada em filmes de asfaltenos, maltenos e/ou resinas. A pressão superficial e os dados de microscopia de fluorescência indicam a presença de domínios fluorescentes em equilíbrio com uma fase menos fluorescente do petróleo contendo água estabilizada. Imagens de BAM e fluorescência de filmes LB confirmam a presença dos domínios de água, mesmo em pressões superficiais elevadas, caracterizando inequivocamente a tendência do petróleo em estabilizar sistemas emulsionados. O aumento da quantidade de asfalteno torna o filme mais instável, devido à formação de agregados irreversíveis. Nossos resultados sugerem que é necessário utilizar amostras de petróleo cru ao invés de suas frações, para entender a estrutura e as propriedades de filmes finos de petróleo. Demonstramos que os agentes coletores tensoativos que comprimem uma mancha de óleo sobre a superfície da água por diferença de pressão superficial, não entram no filme de petróleo, mantendo inalterado a estrutura dos domínios. Investigamos também a capacidade de monocamadas dos ácidos graxos saturados C4 a C18 em comprimir e confinar manchas de petróleo bruto brasileiro e seus derivados. A pressão superficial e a velocidade de espalhamento das monocamadas foram determinadas em uma balança de superfície e pelo teste do talco, respectivamente. A compressão e o confinamento das manchas foram estudados em placas de Petri, medindo-se a área das manchas e a espessura das lentes confinadas. Monocamadas de C8 a C12 foram capazes de comprimir manchas de petróleo formando lentes com cerca de 5% de sua área original. Os melhores resultados foram obtidos com as monocamadas de C8 e C12, que confinaram a mancha de petróleo em uma lente com 5 mm de espessura por até 72 horas sem mudanças significativas em sua área. E para finalizar foi estudado a influência da irradiação com fonte de luz artificial em amostras de petróleo com diferentes porcentagens de asfaltenos e volumes espalhados sobre a água. Tais experimentos foram acompanhados de estudos sobre a geração de oxigênio singlete, espectroscopia de fluorescência e de infravermelho. Caracterizamos que as alterações de pressão superficial e encolhimento da mancha são devidos a oxidação por oxigênio singlete que gera novos compostos tensoativos que comprimem a mancha / Understanding the behavior of petroleum films at the air-water interface is crucial for dealing with oil slicks and consecutive reducing the damages to the environment. For this, Langmuir films prepared with oil fractions have often been studied. However, the properties of films prepared from crude oil samples may differ considerably from those of films prepared from its individual fractions. Films prepared in the ar-water interface with several oil samples with different compositions were studied using spectroscopic and surface techniques including surface pressure, surface potential, BAM, fluorescence and SEM. We showed that petroleum forms an inhomogeneous Langmuir film at the air-water interface. The surface pressure isotherms for petroleum films exhibit gas (G), liquid expanded (LE), liquid condensed (LC) and solid (S) phases, with almost no hysteresis in the compression-decompression cycles, unlike the large hysteresis observed in asphaltenes, maltenes and/or resins films. The surface pressure and fluorescence microscopy data indicate the presence of fluorescent areas in balance with a less fluorescent oil containing water stabilized. BAM and LB films microscopy images confirm the presence of water areas, even at high surface pressures, characterizing unequivocally the trend of petroleum to stabilize emulsion systems. The increase in the amount of asphaltene turned the film more unstable. Our results strongly suggest that it is necessary to use crude oil samples instead of its fractions, to understand the structure and properties of oil thin films. We showed that surface collecting agents, which compress an oil slick on the water surface by surface pressure difference, do not mix in the oil film leaving unchanged the structure at the domains. We also examined the ability of monolayers of C4 to C18 saturated fatty acids in compressing and confining slicks of a Brazilian crude oil and its derivates. Surface pressure and monolayer spreading velocity were measured by the surface balance and by the talc test, respectively. The compression and confinement of the oil slicks were studied in Petri dishes, measuring the area of the slick and the thickness of the confined lenses. Monolayers of C8 and C12 were able to compress oil slicks forming lenses with about 5% of its original area. The best results were obtained with C8 and C12 monolayers, which confined oil slick in a lens with 5 mm thick and up to 72 hours without significant changes in the area. And finally we studied the influence of irradiation with artificial light in oil samples with different percentages of asphaltenes and volumes spread on the water. These experiments were accompanied by studies on the generation of singlet oxygen, fluorescence and infrared spectroscopy. We characterized that the changes of surface pressure and shrinkage of the oil slick is due to oxidation by singlet oxygen and generation of new surfactant compounds that compress the oil slick.

L’objectif de ce projet a été d’explorer les limites et les possibilités d’une réaction tandem photochimique, composée d’une cycloaddition [2+2] entre des cyclopentenones et des alcènes, suivie d’une Norrish I/transfert du γ-hydrogen si l’adduit bicyclique se forme.En utilisant des procédures de la littérature, une petite bibliothèque de cyclopentenones fut préparée. Le developpement de méthodes permettant l’accès à des cyclopentenones substituées, par des réactions d’aldolisation organocatalysées, fut explorée sans succès.Des études photochimiques menées sur une selection de cyclopentenones et d’alcènes ont montré qu’ils pouvaient réagir ensemble pour fournir des cyclobutène aldehydes avec des moyens à bons rendements. Les conditions réactionnelles furent optimisées pour la formation de ce composé et quelques unes des limites en termes de susbtrat furent déterminées. Dans certains cas, un problème de régiosélectivité de la réaction de Norrish I furent constatés. Durant le cette étude, il fut découvert que certains de ces cyclobutène aldéhydes pouvaient eux-mêmes réagir photochimiquement par une réaction de Paternò–Büchi intramoléculaire pour mener à des oxétanes tricycliques totalement inédits. Ceci représente une séquence one-pot de trois réactions photochimiques entre la cyclopentenone de départ et l’alcène. Les conditions opératoires furent optimisées pour cette transformation et plusieurs exemples furent préparés. La structure centrale tricyclique fut étudiée en détail, en solution et dans l’état solide, montrant que la formation de ces oxétanes était hautement diastéréoselective dans certains exemples. Certaines limitations, découlant de gène stérique et/ou l’utilisation d’alcènes électroniquement riches, constituent une limite à la portée de cette réaction. / The aim of this project was to explore the scope and limitations of a tandem photochemical process, consisting of a [2+2] cycloaddition between cyclopentenones and alkenes followed by a Norrish I/γ-hydrogen transfer reaction if the initial bicyclic adduct is formed. Using standard synthetic procedures, a small library of cyclopentenone substrates was prepared. The development of new methods to access substituted cyclopentenones, using organocatalyzed aldolisation conditions, was considered; however, these efforts were unfruitful.The photochemical studies showed that a selection of cyclopentenones and alkenes could react together to furnish cyclobutene aldehydes with average to good yields. The reaction conditions were optimized for the formation of this specific compound type, and some of the limitations as regards substrate diversity were determined. In some cases, control of the regioselectivity of the Norrish-I process was problematic.In course of the study, it was discovered that some of these cyclobutene aldehydes could themselves react photochemically, via an intramolecular Paternò–Büchi reaction, to form hitherto unknown tricyclic oxetanes. This constitutes a one-pot triple photochemical reaction sequence between the starting cyclopenenones and alkenes. Conditions were optimized for this transformation and several examples prepared. The tricyclic core structure was studied in detail, in both solution and the solid state, revealing that the formation had been highly diastereoselective in some examples. Some limitations, arising from steric hindrance and/or use of electron rich alkenes, constituted a limitation of the scope of the process. / Questo progetto ѐ nato con l’obiettivo di sviluppare un processo tandem fotochimico, costituito da una cicloaddizione [2+2] tra olefine e substrati ciclopentenonici, seguita da una reazione di Norrish-I / trasferimento di γ-idrogeno sul prodotto biciclico ottenuto. Usando procedure standard, ѐ stata preparata una libreria di substrati ciclopentenonici da testare in questo processo. Lo studio di nuove metodologie organocatalitiche per la sintesi di tali substrati ѐ stato inoltre intrapreso, sfortunatamente senza buoni risultati.Lo studio di questo processo ha mostrato come una serie di ciclopentenoni sia effettivamente in grado di reagire con doppi legami olefinici, portando alla formazione di derivati aldeidici ciclobutenici, con discrete o buone rese. Le condizioni di reazione sono state ottimizzate per la formazione di questa classe di composti, e alcune limitazioni relative alla struttura del substrato sono emerse da questi studi. In alcuni casi, infatti, il controllo della regioselettività della reazione di Norrish-I si ѐ rivelato problematico.Durante tale studio, ѐ apparso che alcune delle aldeidi ciclobuteniche ottenute si sono rivelate in grado di reagire ulteriormente in condizioni fotochimiche, attraverso una reazione di Paternò–Büchi intramolecolare, portando alla formazione di ossetani triciclici finora sconosciuti. Ciò costituisce in ultima analisi un triplo processo fotochimico one-pot a partire da ciclopentenoni e alcheni. Anche le condizioni di reazione per questa sequenza sono state ottimizzate e alcuni esempi sono stati preparati e isolati. La struttura triciclica di questi nuovi composti e stata caratterizzata nel dettaglio, sia in soluzione che allo stato solido, rivelando un’elevata diastereoselettività in diversi casi. La presenza di gruppi stericamente ingombranti, o l’uso di olefine elettronricche, si sono dimostrati tuttavia una limitazione alla sintesi di queste interessanti strutture.

Photolysis utilises short wavelength ultraviolet radiation to excite and cleave the carbon-chlorine bond of PCBs, yielding less chlorinated PCBs and ultimately biphenyl which can serve as energy and carbon source of various bacteria. Thus integration of photolysis and biodegradation can be a feasible remediation for PCB contamination. / Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants once used as industrial fluids (in hydraulic systems, gas turbines), dielectric fluids (capacitors, transformers), plasticizer (adhesives, textiles, sealants, copy paper), and heat exchangers due to their inertness as well as thermal and electrical insularity. However, they are found to be neurotoxic, immunosuppressive, hepatotoxic, and the USEPA classified PCBs as probable human carcinogens. Although the production of PCBs was banned by the US Congress in 1976, they persist in the environment because of their resistance. Upon entering the marine environment, PCBs will associate with particulates and ultimately with sediment due to their hydrophobic nature and thus sediment become a sink for PCBs. This exerts a threat to marine organisms and human who consume seafood. / The major sink of PCBs in the environment is marine sediment, and the presence of sediment particles as well as other sorbed chemicals may inhibit both photolysis and biodegradation. This study extracts PCBs from sediment and further purify them by various cleanups to prevent the effect of these materials on the efficiency of treatment. / Using 2,4,4'-trichlorobiphenyl (PCB 28), 2,2',5,5'-tetrachlorobiphenyl (PCB 52), 2,2',4,5,5'-pentachlorobiphenyl (PCB 101), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) and 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180) as model compounds, optimal UV intensity, reaction time, as well as reaction solvent were found to be dependent on the congeners used. While PCB 28 was highly reactive and PCB 101, PCB 153 and PCB 180 were comparatively easy to remove, PCB 52 showed high resistance towards photolysis. The photolysis of PCB mixture containing these five congeners with each of them in 1 mg/L was also being optimised. After optimisation, the reaction intermediates and products were identified by gas chromatography coupling mass spectrometry (GC-MS). Less chlorinated congeners and biphenyl were found, indicating stepwise dechlorination of PCB is the major pathway. (Abstract shortened by UMI.) / by Wong Kin Hang. / "August 2005." / Adviser: P. K. Wong. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0159. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 111-140). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Este trabalho relata a síntese, caracterização e a investigação das propriedades fotoluminescentes dos complexos &#946;-dicetonatos (TTA = 2-tenoiltrifluoroacetonato e DBM =dibenzoilmetanato) de terras raras trivalentes (TR3+ = Sm3+, Eu3+ e Gd3+) com diferentes ligantes amidas. Os compostos sintetizados foram caracterizados através das técnicas de microanálises de C, H, e N, espectroscopia de absorção na região do infravermellio e UV-Vis, titulação complexométrica com EDTA, análises termogravimétricas TG/DTG e difratometria de raios-X (métodos do pó e monocristal). Para os ligantes sintetizados, além das duas primeiras técnicas, estes foram caracterizados por Ressonância Magnética Nuclear de próton e carbono 13 (RMN lH e 13C) as quais certificaram suas obtenções e purezas. Os dados de microanálises de CHN e titulação- complexométrica foram concordantes com as fórmulas gerais [TR(TTA)3L2] (exceto [TR(TTA)3(DMFA)(H2O)] e [TR(TTA)3(PZA)]) e [TR(DBM)3L], onde L é um ligante amida. Os espectros de absorção na região do infravermelho evidenciaram o caráter anidro da maioria dos complexos e que a coordenação dos &#946;-dicetonatos e amidas aos íons TR3+ ocorre através dos átomos de oxigênio dos grupos carbonila. As curvas TG/DTG corroboraram os dados dos espectros IV no que se refere à ausência de água coordenada aos íons metálicos (exceto nos complexos precursores e nos [TR(TTA)3(DMFA)(H<sub<2O)]). Os difratogramas de raios-X (método do pó) sugerem a existência de séries isomorfa para cada ligante amida. O complexo [Eu(DBM)3(DMAC)] foi obtido na forma de cristais e sua estrutura foi resolvida pelo método de difração de raios-X de monocristais. Os resultados mostraram que este complexo cristaliza no sistema triclínico, em grupo espacial P-l, com os seguintes parâmetros de cela: a = 10,30&#197;· b = 10,46&#197;·c = 22,67&#197; &#945; = 78,97°; &#946; = 78,58°; &#947; = 63,01°. A primeira esfera de coordenação é descrita como um prisma trigonal monoencapusado, onde sete átomos de oxigênio encontram-se coordenados ao íon Eu3+. As propriedades fotoluminescentes dos íons Sm3+ e Eu3+ nos complexos foram investigadas a partir dos espectros de excitação, emissão e curvas de decaimento de luminescência. Os espectros de emissão desses complexos mostraram, principalmente, bandas finas oriundas das transições intraconfiguracionais-4fN 4G5/2 &#8594; 6H5/2, 7/2, 9/2, 11/2 (Sm3+)e 5D0 &#8594; 7F0, 1, 2, 3,4 (Eu3+), dominados pelas transições hipersensíveis 4G5/2 &#8594; 6H9/2 (~645 nm) e 5D0 &#8594; 7F2 (~612 nm). Os desdobramentos dessas transições, de um modo geral, estão concordantes com um ambiente químico de baixa simetria ao redor do íon TR3+. Com base nos dados espectrais foram determinados os parâmetros de intensidade &#937;2 e &#937;4, os coeficientes de emissão radiativa (Arad) e não-radiativa (Anrad) e a eficiência quântica de emissão experimental do nível 5D0 do íon Eu3+ (&#951;). Os complexos de DBM apresentam maiores valores de &#937;2 do que aqueles com TTA, refletindo um ambiente químico mais polarizável com maior caráter covalente da ligação Eu3+-DBM. Os valores dos parâmetros experimentais (&#951;Sm e &#951;Eu) dos complexos de Sm3+ e Eu3+ apresentaram uma boa correlação, evidenciando que a polarizabilidade em tomo do íon Sm3+ é semelhante àquela nos complexos com o íon Eu3+. Observou-se que os valores de eficiência quântica do estado emissor 5D0 (&#951;) aumentam quando as moléculas de água são substituídas pelos ligantes amidas. Esses resultados são devidos a uma diminuição significativa dos processos não radiativos (Anrad) pela ausência dos supressores O-H nos complexos com ligantes amidas. No entanto, no caso do complexo com PZA, foi observado um valor de Anrad grande, sugerindo um forte acoplamento dos osciladores N-H com o estado excitado 5D0. Os valores altos de rendimentos quânticos experimentais, qa, da maioria dos complexos indicam que a transferência de energia Ligante-Eu3+ é muito eficiente. É importante salientar que o complexo [Eu(TTA)3(DMBZ)2] apresenta um dos maiores valores de rendimento quântico experimental ( q = 82 %) da literatura para compostos de coordenação com o íon Eu3+. Os processos de transferência de energia Ligante-Eu3+ foram investigados por modelos teóricos SMLC (Sparkle Model for Lanthanide Complexes). A estrutura do complexo [Eu(DBM)3(DMAC)] apresentou boa concordância com aquela determinada experimentalmente através da técnica de difração de raios-X. De um modo geral, o poliedro de coordenação ao redor do íon Eu3+ nas estruturas teóricas está, também, concordante com o desdobramento das bandas associadas às transições 5D0 &#8594; 7FJ. Os dados das taxas de transferência de energia determinados utilizando um conjunto apropriado de equações de taxa concordaram muito bem com os dados experimentais evidenciando a viabilidade do modelo teórico nos estudos de compostos de coordenação com íons terras raras trivalente. O comportamento fotoluminescente exibido pelos complexos de európio evidencia que este sistema atua como Sistemas Moleculares Conversores de Luz. / This work reports the synthesis, characterization and investigations of photoluminescent properties of &#946;-diketonate complexes (TTA = 2-thenoiltrifluoroacetonate and DBM = dibenzoylmethanate) of trivalent rare earths (TR3+ = Sm3+, Eu3+ e Gd3+) with different amide ligands. The synthesized compounds were characterized by the fol1owing techniques: microanalyses of C, H, and N, absorption spectroscopy in the infrared region and UV-Vis, complexometric titration with EDTA, thermogravimetric analyses TG/DTG and X-rays diffraction (powder and single crystal methods). In case of ligands, besides the two first techniques, they were also characterized by Magnetic Nuclear Resonance of proton and carbon 13 (MNR 1H and 13C) which were according with the expected results and indicated the higher purity degree of these ligands. The elemental analyses data of C, H, and N, and complexometric titration suggested the general formulas [TR(TTA)3L2] (except for [TR(TTA)3(DMFA)(H2O)] and [TR(TTA)3(PZA)]) and [TR(DBM)3L], where L is amide ligand. The infrared spectra indicated that the complexes are anhydrous and that the coordination of &#946;-diketonates and amides to the TR3+ ions occurs via oxygen atoms. TG/DTG curves corroborate with the IR data suggesting the absence of water molecules coordinated to the metal ions (except for the case of the precursors and [TR(TTA)3(DMFA)(H2O)] complexes). Besides, these curves indicated that the amide complexes show a higher thermal stability (~150 °C). The XRD diffractograms (powder method) suggest the presence of one isomorphic series for each amide ligand. The [Eu(DBM)3(DMAC)] complex was obtained in the single crystal form to obtain its structure by rays-X diffraction (single crystal method). The structural results showed that this complex crystallize in a triclinic system, as a spatial group P-1, with the following cell parameters: a = 10.30 &#197;; b = 10.46 &#197;; c = 22.67 &#197;; &#945; = 78.97 °; &#946; = 78.58 °; &#947 = 63.01 °. The first coordination sphere is described as a monocapped trigonal prism, with seven oxygen atoms bonded to the Eu3+ ion (six from the &#946;-diketonate chelate and one from amide ligand). The photoluminescent properties of the Sm3+ and Eu3+ -complexes were investigated by the excitation, emission and luminescent decay curves, recorded at room and liquid nitrogen temperatures. The emission spectra of the complexes displayed mainly the narrow bands arising from 4f-intraconfigurational transitions 4G5/2 &#8594; 6H5/2, 7/2, 9/2, 11/2 (Sm3+) and 5D0 >&#8594; 7F0, 1, 2, 3,4, (Eu3+), dominated by the hypersensitive bands due to the transitions 4G5/2 &#8594; 6H9/2 (~645 nm) and 5D0 &#8594; 7F2 (~612 nm), respectively. The splits of these transitions agree with the presence of a chemical environment with the low symmetry around the TR3+ ion. The intensity parameters (&#937;2 and &#937;4), the radiative (Arad) and non-radiative decay rates and the quantum emission efficiency of the 5D0 were obtained by the quantitative analyses of the emission spectra of the Eu3+ -complexes. The &#937;2 values were higher for the DBM than for the TTA-complexes, reflecting that the chemical environment are more polarizable around Eu3+ ion in the complexes with DBM, indicating the highest covalent character of the Eu3+ -DBM bond. It was observed that the &#951; values were increased when the water molecules were replaced by the amide ligands. These results reflect the decrease of the non-radiative rates (Anrad), which is a consequence of the absence of the O-H quenchers. However, it was observed that the complex with PZA ligand presents Anrad as high as that value in the hydrated complex, suggesting strong coupling of the N-H oscillators with the excited level. The experimental quantum yield, qa, of the complexes of europium ion in the solid state present a good correlations with the quantum emission efficiency, &#951;, indicated a very efficient energy transfer Ligand-to-Eu3+. It is important to notice, that the qa value for the [Eu(TTA)3(DMBZ)] (q = 82 %) complex is among the highest values reported in the literature for the coordination compound with Eu3+ ion. The energy transfer processes from ligand to metal were investigated by the theoretical models SMLC (Sparkle Model for the Calculation of Lanthanide Complexes). The theoretical structure of the complex [Eu(DBM)3(DMAC)] agrees with that one determined experimentally by X-ray diffraction. It was also observed that the coordination polyhedron around the Eu3+ ion (in the theoretical structures) corroborates with the split of the bands assigned to the 5D0 &#8594; 7FJ transitions. The energy transfer rates determined by the appropriated rate equations agree with the experimental quantum yield, suggesting the viability of theoretical model on studies of the trivalent rare earth coordination compounds The photoluminescent behavior exhibited by the europium complexes indicates that this system acts as Light Molecular Conversion Systems.

O trabalho apresenta o desenvolvimento de células solares fotoeletroquímicas baseadas na sensibilização de n-TiO2 por corantes sintéticos e naturais. Abrange as etapas envolvidas na sua obtenção, desde a preparação dos compostos sensibilizadores, filmes semicondutores e meio eletrolítico, até a montagem e medidas de eficiência, com a otimização dos diversos componentes do sistema, num arranjo do tipo sanduíche. O fotoanodo consiste num filme de TiO2 nanocristalino sensibilizado pelo corante num substrato condutor. O contraeletrodo é composto de um substrato condutor recoberto com camada transparente de platina. Entre os eletrodos é disposta a camada de eletrólito, geralmente solução de l2/Lil em acetonitrila. A espessura do filme de semicondutor é controlada com os métodos empregados na deposição de sua dispersão. A transparência final depende ainda do método de preparação das dispersões. Utilizando as espécies cis-[(dcbH2)2RuLL\')2+, dcbH2 = 4,4\'-(CO2H)2-2,2\'bipiridina e L/L\' = cianopiridina, quinolina e H2O, como sensibilizador, obteve-se conversão eficiente de luz visível em eletricidade com valores de IPCE de até 50 % entre 400 e 550 nm. Os processos de transferência e recombinação de elétron na interface sensibilizador/semicondutor foram investigados por experimentos com técnicas resolvidas no tempo empregando sensibilizadores ancorados aos filmes transparentes de TiO2. O trabalho envolveu ainda incorporações técnicas para aumentar a eficiência da célula, como filamentos metálicos protegidos e a combinação de unidades independentes numa associação modular, que são objetos de patentes depositadas. / This work presents the development on photoelectrochemical solar cells based on sensitization of n-TiO2 by synthetic and natural dyes. It comprises several steps involved in the fabrication and assembling of the cells in a sandwich-type design. Preparation of sensitizers, semiconductor films and electrolyte media, as well as efficiency measurements and optimization of several components are presented. The photoanode consists of a dye-sensitized nanocrystalline n-TiO2 film onto a conductive substrate. The counterelectrode is a conductive substrate covered with a thin, transparent platinum layer. The electrolyte layer, usually l2/Lil in acetonitrile, is placed between the electrodes. The deposition process of the semiconductor dispersion onto the substrates regulates the resulting thickness of the film. The final transparency is also controlled by the procedure employed in the preparation of the semiconductor dispersion. The species cis-[(dcbH2)2RuLL\']2+, dcbH2 = 4,4\'-(CO2H)2-2,2\'-bipyridine and L/L\' = 4-cyanopyridine, quinoline and H2O, were employed as sensitizers resulting in IPCE (Incident Monochromatic Photon to Current Conversion Efficiency) values as high as 50 % from 400 to 550 nm. Electron transfer and recombination processes across the semiconductor/sensitizer interface were investigated with time-resolved experiments employing transparent films of n-TiO2 sensitized by the anchored species. Other approaches aiming improvements in efficiencies and the preparation of photoelectrochemical solar cells for different applications or through environmentally friendly processes are discussed. The use of protected metallic filaments and the modular arrangement of single cells are issues of patents.

Uma série de compostos de transferência de carga baseado em derivados de anilina (grupo doador) e N-alquilpiridínio (grupo receptor) foi preparada e ligada à periferia do anel porfirínico, gerando uma nova série de porfirinas supermoleculares, que foram caracterizadas por espectroscopia eletrônica, voltametria cíclica, espectroeletroquímica, fluorescência e fotólise relâmpago. Os compostos foram preparados no laboratório do Prof. Silviu Balaban, no Instituto de Nanotecnologia do Forschungszentrum Karlsruhe, visando o estudo da interação entre a porfirina e aqueles compostos de transferência de carga, particularmente o efeito da estrutura molecular sobre as as propriedades fotoquímicas. As porfirinas foram projetadas tendo como modelo o sistema antena de algumas bactérias verdes fotossintéticas, visando obter fotossensibilizadores mais eficientes acoplando processos de transferência de energia (efeito antena) para o sítio porfirínico ativo, aumentando a eficiência de absorção/conversão na região do visível, melhorando assim o aproveitamento da energia solar. De fato, os sensibilizadores porfirínicos supermoleculares que foram objeto de estudo desta tese, apresentaram apenas um eficiente mecanismo de transferência de energia intramolecular para o grupo porfirínico; e as ligações amida ou éster utilizadas para ligar os grupos parecem não influenciar significativamente a eficiência do efeito antena. Os estudos de fluorescência e de fotólise relâmpago indicaram que os estados excitados singlete e triplete de menor energia estão localizados na porfirina, e que não há competição significativa de processos paralelos de supressão do estado excitado, por exemplo pelo mecanismo redox, apesar dos potenciais serem termodinamicamente favoráveis. Porém, pode haver transferência de carga do grupo derivado de anilina para a porfirina oxidada após a injeção de elétrons fotoinduzida para o filme de TiO2 nanocristalino, melhorando o processo de separação de cargas. Em suma, os materiais porfirínicos apresentam características adequadas e potencialidade para uso como fotossensibilizadores em dispositivos fotoeletroquímicos e fotovoltáicos. / A series of charge-transfer compounds constituted by anilline and Nalkylpyridynium derivatives as donor and acceptor groups was prepared and bond to the meso-position of a porphyrin to get a new series of supermolecular porphyrins, that were characterized by UV-Vis and fluorescence spectroscopy, cyclic voltammetry, spectroelectrochemistry and flash-photolysis. The series of compounds were synthesized in the Prof. Silviu Balaban Lab, at the Forschungszentrum Karlsruhe Institute of Nanotechnology aiming the study of the properties coming out of the interaction of porphyrins and donor-acceptor charge-transfer complexes, particularly the influence of the molecular structure on the photophysical properties. The supermolecular porphyrins were designed using the antenna system of photosynthetic green bacteria as model, in order to obtain more efficient photosensitizers by enhancing the light harvesting efficiency of porphyrins incorporating the energy-transfer effect. In fact, the charge-transfer complexes bound to the porphyrin ring were shown to interact exclusively through energy-transfer, and the amide or esther used to bridge those components didnt influence significantly the efficiency of that process. The lowest excited state was found to be localized on the porphyrin ring in the singlet and triplet excited state, by fluorescence and flashphotolysis studies. More interestingly, the results indicated that there is no competition of parallel deactivation mechanisms, such as redox mechanism, even though the potentials are thermodynamically favorable. However, charge-transfer from the donor anilline derivatives to the oxidized porphyrin site can take place immediately after photoinduced injection of an electron to nanocrystalline TiO2, improving the charge-separation process. In conclusion, the supermolecular porphyrins exhibited suitable properties as photosensitizers in photoelectrochemical and photovoltaic devices.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-08-18T16:17:20Z No. of bitstreams: 1 2010 - Janaina de Faria Rodrigues.pdf: 2153676 bytes, checksum: 8429cd74e923c45f3d05970bcdff87d2 (MD5) / Made available in DSpace on 2017-08-18T16:17:20Z (GMT). No. of bitstreams: 1 2010 - Janaina de Faria Rodrigues.pdf: 2153676 bytes, checksum: 8429cd74e923c45f3d05970bcdff87d2 (MD5) Previous issue date: 2010-06-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, CNPq, Brasil. / By laser flash photolysis, the photo-reactivity of the triplet excited state of thioxanthone derivatives (2BTX, 2MeOTX, 2PrOTX and 2MeTX) was studied. The maximum wavelength and triplet time life of theirs transients are solvent dependents, a blue-shift is observed with the change of no polar to polar middle and still more in hydroxyl solvent. The triplet spectrum with hydrogen-donor solvents shows a slower broad band between 430-460nm that again is observed with hydrogen-donor quenchers, this band is attributed to ketyl radical. The broad bands in 410 and 500nm are attributed to phenoxyl, indolyl radicals and ions radicals as intermediates, respectively. The higher values to hydrogen transference from alcohols (~105 M-1s-1) and allylic hydrocarbons and phenols (~109 M-1s-1) are attributed to the triplet excited state of lower energy have a mixture of excited states with predominant character of the excited state with n?*. The no dependence to substituted-phenols on Kq and the approximated values between then and TEA, DABCO and indole (~109 M-1s-1) are indicating a mechanism by electron-transference followed a faster proton transference from an exciplex. The quenching rate contants by transfer of energy from trans-stilbene, 1-methylnaphthalene and 1,3-cyclohexadiene are controlled by diffusion for 2MeTX remaining triplet energy over 61 kcal.mol-1, as observed for TX. For the other substituents was a decrease in triplet energy is getting between 53 and 61 kcal.mol-1. / Utilizando-se a t?cnica de fot?lise por pulso de laser, foram estudadas a fotorreatividade do estado triplete de derivados de tioxantona (9-H-tioxanton-9-ona). Os espectros de absor??o T1?Tn para os derivados 2-benzil?xi, 2-met?xi, 2-prop?xi e 2-metil (2BTX, 2MeOTX, 2PrOTX e 2MeTX), obtidos em diversos solventes, mostram que estes se comportam de forma selhante a tioxantona. O comprimento de onda m?ximo bem como o tempo de vida de seus transientes s?o dependentes da polaridade do meio. Observou-se o deslocamento hipsocr?mico com a mudan?a de um solvente apolar para um solvente polar, tendo sido mais acentuado para os solventes polares hidroxil?cos. Nos espectros de absor??o T1?Tn em solventes doadores de hidrog?nio foi poss?vel observar a forma??o de uma banda entre regi?o de 430-460nm que foi observada novamente nas rea??es com supressores de energia triplete doadores de hidrog?nio, sendo esta banda atribu?da ao radical cetila. As bandas formadas na regi?o de 410 e 500nm s?o atribu?das ao radical fenoxila e indolila, respectivamente. Os altos valores para as constantes de velocidade de rea??o de supress?o por transfer?ncia de hidrog?nio com ?lcoois (~105 M-1s-1), hidrocarbonetos al?licos e fen?is (~109 M-1s-1) s?o atribu?dos ao fato de que o estado excitado triplete de mais baixa energia apresentar uma mistura de estados excitado com predomin?ncia do car?ter n?*. A n?o depend?ncia das kq para os fen?is de seus substituintes e os valores pr?ximos das rea??es para trietilamina, DABCO e indol indicam que o mecanismo de rea??o passa por uma primeira etapa de transfer?ncia de el?trons seguida de uma r?pida transfer?ncia de pr?ton a partir da forma??o de um exciplexo. As constantes de velocaide de rea??o de supress?o por transfer?ncia de energia com trans-estilbeno, 1-metil-naftaleno e 1,3-cicloexadieno s?o controladas por difus?o para 2MeTX estando a energia triplete de T1 acima de 61 kcal.mol-1, como o observado para a TX; j? para os demais substituintes houve uma diminui??o da energia triplete ficando esta entre 53 kcal.mol-1 e 61 kcal.mol-1.

Dietary fish oil supplementation has long been shown to have significant health benefits, largely stemming from the anti-inflammatory activity of the ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) present in fish oils. The anti-inflammatory properties of these fatty acids has been linked to beneficial health effects, such as protecting the heart, in individuals consuming diets rich in fish, or supplemented with fish oils. These effects are highly notable in the Māori people native to coastal regions of New Zealand; the significantly lower rates of heart problems compared to the inland populous has been attributed to the consumption of the green lipped mussel Perna Canaliculus. Commercially available health supplements based on the New Zealand green lipped mussel include a freeze-dried powder and a lipid extract (Lyprinol®), the latter of which has shown anti-inflammatory properties comparable to classical non-steroidal anti-inflammatory drugs (NSAIDs) such as Naproxen. GCMS analysis of Lyprinol by Murphy et al. showed the presence of a class of ω-4 and ω-6 PUFAs bearing a highly electron rich tri- or tetra-alkyl furan ring, which were designated furan fatty acids (F-acids). Due to their instability, isolation of F-acids from natural sources cannot be carried out and a general synthetic route toward this class of natural products was required. To accomplish this, the biosynthesis of F-acids was mimicked by utilising an oxidation of 1,3-dienes, followed by a dehydration/aromatisation to generate the heterocyclic furan ring. Singlet oxygen was chosen as the means of oxidising the conjugated dienes giving endoperoxides. To mimic the biological aromatisation of the peroxide intermediates the Appel reagent was chosen and, in a novel application of the reagent, was exploited as a mild, metal free method of dehydrating the cyclic peroxides to their corresponding furans. The biomimetic furan synthesis was applied toward a selection of 1,3-diene substrates bearing a range of pre-installed functionalities and substitution patterns including alkyl, aryl, alkenes, cyclopropyl rings, silyl ethers, and esters, alongside being applied to the total synthesis of the furan fatty acid F5. A brief exploration of the possibility of performing the aromatisation reaction under catalytic conditions was carried out, to determine whether endoperoxides could be converted to furans without needing a stoichiometric quantity of Appel reagent, by harnessing a catalytic quantity of triphenylphosphine oxide and regenerating the active P(V) species via reaction with oxalyl chloride. Furthermore, an optimisation study was carried out using a simple design of experiments procedure to ascertain the ideal conditions for carrying out the Appel-type dehydration of endoperoxides. Finally, the scope of the reaction sequence was expanded to be performed in a continuous flow reactor, with telescoping of the singlet oxygen diene oxidation and Appel-type aromatisation to increase oxidation yields and to omit the requirement for isolation of peroxide intermediates, and was applied to the synthesis of a selection of 2,5-diaryl furan motifs.