Contents of hydrocarbons in waters and bottom sediments of the southwestern Amur Bay (Sea of Japan) in April 2005

Abundances and compositions of aliphatic hydrocarbons (AHC) and polyaromatic hydrocarbons (PAH) were investigated in water and bottom sediments of the southwestern Amur Bay, Sea of Japan. Water contained 0-129 ?g/l AHC (average 42.2 ?g/l) and 5-85 ng/l PAH (average 18 ng/l). Bottom sediments contained 168-2098 ?g/g AHC and 7.2-1100 ng/g dry mass PAH. It was shown that input of anthropogenic hydrocarbons is better recorded by molecular markers than by distribution of AHC and PAH concentrations. Discovery of elevated hydrocarbon concentrations in the bottom water layer suggests that bottom sediments induced secondary contamination of the water body.

A importância do uso de métodos complementares para a avaliação da toxicidade de hidrocarbonetos aromáticos policíclicos

Hidrocarbonetos Aromáticos Policíclicos (HAPs) e seus derivados Halogenados (HHAPs) são conhecidos como um conjunto de contaminantes ambientais, classificados como potencialmente tóxicos, mutagénicos e carcinogénicos, sendo um assunto de extrema importância e preocupação para a saúde pública. Diversos estudos têm reportado o potencial efeito tóxico destes compostos após longos períodos de exposição, pelo uso de métodos colorimétricos como o ensaio de brometo de 3-[4,5- dimetil-tiazol-2-il]-2,5-difeniltetrazólio (MTT) e vermelho neutro. Contudo, apesar de estes métodos clássicos de avaliação da citotoxicidade in vitro permitirem, de forma rápida, identificar as propriedades nocivas dos compostos, não permitem compreender os mecanismos moleculares subjacentes responsáveis pela sua toxicidade. Deste modo, no presente estudo, para avaliar os efeitos à exposição aos compostos Pireno (Pir) e seu derivado resultante da desinfeção de águas por bromação, 1-BromoPireno (1-BrPir), foram utilizados outros métodos complementares como avaliação do stress oxidativo e vários fenómenos associados à morte celular programada. Os resultados obtidos comprovam não só a existência de efeitos citotóxicos dos poluentes quando acumulados, como também possíveis efeitos genotóxicos. Assim, pelos métodos complementares, foi possível a identificação de alvos moleculares passiveis de ação farmacológica, o que pode constituir o primeiro passo para o desenho de estratégias terapêuticas que visem prevenir ou tratar os danos provocados por estes poluentes no Homem.

(E)-2-[2-(2-Aminofenil)vinil]-1-metilquinolin-4(1H)-ona como precursor de novos compostos heterociclicos

Esta dissertação reporta a síntese de novos derivados de 4-quinolonas com potencial atividade biológica e está dividida em 3 capítulos. No primeiro capítulo é feita uma breve introdução aos compostos do tipo 4quinolona, azepina e indol, focando a nomenclatura, atividade biológica e métodos de síntese mais comuns deste tipo de compostos, e é apresentada a nomenclatura dos compostos sintetizados ao longo deste trabalho. No segundo capítulo são descritas as metodologias desenvolvidas para obtenção dos compostos pretendidos. Foram sintetizados novos derivados de 4-quinolonas via reações de N-metilação seguida de ciclização in situ da (E)-N(2-acetilfenil)-3-(2-nitrofenil)acrilamida, via reações de redução da 1-metil-2-[2(2-nitrofenil)vinil]quinolin-4(1H)-ona e reações de halogenação da 1-metil-2-[2(2-nitrofenil)vinil]quinolin-4(1H)-ona e da 2-[2-(2-aminofenil)vinil]-1metilquinolin-4(1H)-ona. Posteriormente, fizeram-se estudos de reatividade da 1-metil-2-[2-(2-nitrofenil)vinil]quinolin-4(1H)-ona e da 2-[2-(2-aminofenil)vinil]-3bromo-1-metilquinolin-4(1H)-ona. Na reação de redução in situ seguida de ciclização intramolecular da 1-metil-2-[2-(2-nitrofenil)vinil]quinolin-4(1H)-ona obteve-se a 2-(1H-indol-2-il)-1-metilquinolin-4(1H)-ona. Partindo da 2-[2-(2aminofenil)vinil]-3-bromo-1-metilquinolin-4(1H)-ona via reações de BuchwaldHartwig obteve-se a 11-metil-5H-benzo[6,7]azepino[3,2-b]quinolin-6(11H)-ona. Novas N-[2-(2-(3-bromo-1-metil-4-oxo-1,4-di-hidroquinolin-2il)vinil)fenil]alquilamidas foram obtidas via reações de acilação da 2-[2-(2aminofenil)vinil]-3-bromo-1-metilquinolin-4(1H)-ona em piridina seca usando diferentes cloretos de acilo. Numa tentativa de ciclização intramolecular da N[2-(2-(3-bromo-1-metil-4-oxo-1,4-di-hidroquinolin-2-il)vinil)fenil]-hexanamida via reação de Ullmann intramolecular foi obtida a 2-(1-hexanoil-1H-indol-2-il)-1metilquinolin-4(1H)-ona. Após a descrição detalhada das metodologias de síntese são apresentadas as principais conclusões deste trabalho e perspectivas futuras. Por último, no terceiro capítulo, são apresentados os procedimentos experimentais usados para obtenção dos compostos sintetizados e os dados relativos à sua caracterização estrutural, que foi sendo discutida ao longo do segundo capítulo. Os compostos sintetizados foram caracterizados por espetroscopia de ressonância magnética nuclear monodimensional (1H e 13C) e bidimensional (HSQC, HMBC) e por espetrometria de massa e sempre que possível por espetrometria de massa de alta resolução.

Firefighters' exposure biomonitoring: Impact of firefighting activities on levels of urinary monohydroxyl metabolites

The concentrations of six urinary monohydroxyl metabolites (OH-PAHs) of polycyclic aromatic hydrocarbons, namely 1-hydroxynaphthalene, 1-hydroxyacenaphthene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene (1OHPy), and 3-hydroxybenzo[a]pyrene, were assessed in the post-shift urine of wildland firefighters involved in fire combat activities at six Portuguese fire corporations, and compared with those of non-exposed subjects. Overall, median levels of urinary individual and total OH-PAHs (ΣOH-PAHs) suggest an increased exposure to polycyclic aromatic hydrocarbons during firefighting activities with ΣOH-PAH levels in exposed firefighters 1.7-35 times higher than in non-exposed ones. Urinary 1-hydroxynaphthalene and/or 1-hydroxyacenapthene were the predominant compounds, representing 63-98% of ΣOH-PAHs, followed by 2-hydroxyfluorene (1-17%), 1-hydroxyphenanthrene (1-13%), and 1OHPy (0.3-10%). A similar profile was observed when gender discrimination was considered. Participation in fire combat activities promoted an increase of the distribution percentage of 1-hydroxynaphthalene and 1-hydroxyacenaphthene, while contributions of 1-hydroxyphenanthrene and 1OHPy decreased. The detected urinary 1OHPy concentrations (1.73×10(-2) to 0.152μmol/mol creatinine in exposed subjects versus 1.21×10(-2) to 5.44×10(-2)μmol/mol creatinine in non-exposed individuals) were lower than the benchmark level (0.5μmol/mol creatinine) proposed by the American Conference of Governmental Industrial Hygienists. This compound, considered the biomarker of exposure to PAHs, was the less abundant one from the six analyzed biomarkers. Thus the inclusion of other metabolites, in addition to 1OHPy, in future studies is suggested to better estimate firefighters' occupational exposure to PAHs. Moreover, strong to moderate Spearman correlations were observed between individual compounds and ΣOH-PAHs corroborating the prevalence of an emission source.

Développement et caractérisation de dérivés dipyrrométhène pour des applications dans le domaine du photovoltaïque

Ce projet de recherche mené en collaboration industrielle avec St-Jean Photochimie Inc. / PCAS Canada vise le développement et la caractérisation de dérivés dipyrrométhène pour des applications dans le domaine du photovoltaïque. La quête du récoltage des photons se situant dans le proche-infrarouge a été au centre des modifications structurales explorées afin d’augmenter l’efficacité de conversion des cellules solaires de type organique et à pigments photosensibles. Trois familles de composés intégrant le motif dipyrrométhène ont été synthétisées et caractérisées du point de vue spectroscopique, électrochimique, structural ainsi que par modélisation moléculaire afin d’établir des relations structures-propriétés. La première famille comporte six azadipyrrométhènes au potentiel de coordination tétradentate sur des centres métalliques. Le développement d’une nouvelle voie synthétique asymétrique combinée à l’utilisation d’une voie symétrique classique ont permis d’obtenir l’ensemble des combinaisons de substituants possibles sur les aryles proximaux incluant les noyaux 2-hydroxyphényle, 2-méthoxyphényle et 2- pyridyle. La modulation du maximum d’absorption dans le rouge a pu être faite entre 598 et 619 nm. De même, la présence de groupements méthoxyle ou hydroxyle augmente l’absorption dans le violet (~410 nm) tel que démontré par modélisation. La caractérisation électrochimique a montré que les dérivés tétradentates étaient en général moins stables aux processus redox que leur contre-parti bidentate. La deuxième famille comporte dix dérivés BODIPY fusionnés de façon asymétrique en position [b]. L’aryle proximal a été modifié de façon systématique afin de mieux comprendre l’impact des substituents riches en électron et de la fusion de cycles aromatiques. De plus, ces dérivés ont été mis en relation avec une vaste série de composés analogues. Les résultats empiriques ont montré que les propriétés optoélectroniques de la plateforme sont régies par le degré de communication électronique entre l’aryle proximal, le pyrrole sur lequel il est attaché et le noyau indolique adjacent à ce dernier. Les maximums d’absorption dans le rouge sont modulables entre 547 et 628 nm et la fluorescence des composés se situe dans le proche- infrarouge. L’un des composé s’est révélé souhaitable pour une utilisation en photovoltaïque ainsi qu’à titre de sonde à pH. La troisième famille comporte cinq complexes neutres de RuII basés sur des polypyridines et portant un ligand azadipyrrométhène cyclométalé. Les composés ont montré une forte absorption de photons dans la région de 600 à 800 nm (rouge à proche- infrarouge) et qui a pu être étendue au-delà de 1100 nm dans le cas des dérivés portant un ligand terpyridine. L’analyse des propriétés optoélectroniques de façon empirique et théorique a montré un impact significatif de la cyclométalation et ouvert la voie pour leur étude en tant que photosensibilisateurs en OPV et en DSSC. La capacité d’un des complexes à photo-injecter un électron dans la bande de conduction du semi-conducteur TiO2 a été démontré en collaboration avec le groupe du Pr Gerald J. Meyer à University of North Carolina at Chapel Hill, premier pas vers une utilisation dans les cellules solaires à pigments photosensibles. La stabilité des complexes en solution s’est toutefois avérée problématique et des pistes de solutions sont suggérées basées sur les connaissances acquises dans le cadre de cette thèse.

Nuevas aplicaciones sintéticas de pequeños heterocíclos. 2H-Azirinas fosforadas.

238 p.

Preferential location of lidocaine and etidocaine in lecithin bilayers as determined by EPR, fluorescence and H-2 NMR

We have examined the effect of the uncharged species of lidocaine (LDC) and etidocaine (EDC) on the acyl chain moiety of egg phosphatidylcholine liposomes. Changes in membrane organization caused by both anesthetics were detected through the use of EPR spin labels (5, 7 and 12 doxyl stearic acid methyl ester) or fluorescence probes (4, 6, 10, 16 pyrene-fatty acids). The disturbance caused by the LA was greater when the probes were inserted in more external positions of the acyl chain and decreased towards the hydrophobic core of the membrane. The results indicate a preferential insertion of LDC at the polar interface of the bilayer and in the first half of the acyl chain, for EDC. Additionally, 2 H NMR spectra of multilamellar liposomes composed by acyl chain-perdeutero DMPC and EPC (1:4 mol%) allowed the determination of the segmental order (S-mol) and dynamics (T-1) of the acyl chain region. In accordance to the fluorescence and EPR results, changes in molecular orientation and dynamics are more prominent if the LA preferential location is more superficial, as for LDC while EDC seems to organize the acyl chain region between carbons 2-8, which is indicative of its positioning. We propose that the preferential location of LDC and EDC inside the bilayers creates a "transient site", which is related to the anesthetic potency since it could modulate the access of these molecules to their binding site(s) in the voltage-gated sodium channel. (C) 2007 Elsevier B.V. All rights reserved.

Photocatalytic Dehydrogenative Lactonization of 2-Arylbenzoic Acids

A metal-free dehydrogenative lactonization of 2-arylbenzoic acids at room temperature was developed. This work illustrates the first application of visible-light photoredox catalysis in the preparation of benzo-3,4-coumarins, an important structural motif in bioactive molecules. The combination of photocatalyst [Acr+-Mes] with (NH4)2S2O8 as a terminal oxidant provides an economical and environmentally benign entry to different substituted benzocoumarins. Preliminary mechanistic studies suggest that this reaction most likely occurs through a homolytic aromatic substitution pathway.

Graphene and Semicondutor or Metallic Nanoparticles for Energy Conversion

The purpose of the present PhD thesis is to investigate the properties of innovative nano- materials with respect to the conversion of renewable energies to electrical and chemical energy. The materials have been synthesized and characterized by means of a wide spectrum of morphological, compositional and photophysical techniques, in order to get an insight into the correlation between the properties of each material and the activity towards different energy conversion applications. Two main topics are addressed: in the first part of the thesis the light harvesting in pyrene functionalized silicon nanocrystals has been discussed, suggesting an original approach to suc- cessfully increase the absorption properties of these nanocrystals. The interaction of these nanocrystals was then studied, in order to give a deeper insight on the charge and energy extraction, preparing the way to implement SiNCs as active material in optoelectronic devices and photovoltaic cells. In addition to this, the luminescence of SiNCs has been exploited to increase the efficiency of conventional photovoltaic cells by means of two innovative architectures. Specifically, SiNCs has been used as luminescent downshifting layer in dye sensitized solar cells, and they were shown to be very promising light emitters in luminescent solar concentrators. The second part of the thesis was concerned on the production of hydrogen by platinum nanoparticles coupled to either electro-active or photo-active materials. Within this context, the electrocatalytic activity of platinum nanoparticles supported on exfoliated graphene has been studied, preparing an high-efficiency catalyst and disclosing the role of the exfoliation technique towards the catalytic activity. Furthermore, platinum nanoparticles have been synthesized within photoactive dendrimers, providing the first proof of concept of a dendrimer-based photocatalytic system for the hydrogen production where both sensitizer and catalyst are anchored to a single scaffold.

Sintesi e proprietà fotovoltaiche di polimeri contenenti gruppi elettron donatori e accettori in catena principale

Negli ultimi anni è notevolmente aumentato l’interesse nei confronti dei materiali organici semiconduttori da utilizzare in diversi dispositivi, come, ad esempio, celle fotovoltaiche organiche (OPV). In questo campo si inseriscono i polimeri coniugati ed in particolar modo i polialchiltiofeni (PATs). In questa tesi di laurea magistrale vengono descritte sintesi di monomeri e polimeri tiofenici 3-alchil-sostituiti contenenti un'unità elettron accettrice di benzotiadiazolo. In particolar modo sono stati sintetizzati poli-4,7-bis-(3-esiltiofen-2-il)benzo [1,2,5]tiadiazolo e poli- 4,7 -bis-(3-metossiesiltiofene-2-il)benzo[1,2,5]tiadiazolo, studiando l’effetto dell’ossigeno presente in catena laterale sulle proprietà del materiale. È stata effettuata la caratterizzazione chimico fisica dei polimeri tramite analisi termiche DSC e TGA, cromatografia a permeazione su gel (GPC) e analisi UV-Vis e PL. Sono state inoltre effettuate prove di conducibilità testando i polimeri come materiali fotoattivi in celle fotovoltaiche SMOCs e BHJ, per valutare l’effetto dell’unità di benzotiadiazolo sul trasporto delle cariche.

Excited state energy surfaces of flexible emitters for thermally activated delayed fluorescence

Organic Light-Emitting Diodes (OLEDs) technology has matured over recent years, reaching the commercialization level and being used in various applications. The required efficiency can be achieved by transforming triplet excitons into singlet states via Reverse InterSystem Crossing (RISC), which a general mechanism called thermally activated delayed fluorescence (TADF). Two prototypical molecules in the field, 2CzBN and 4CzBN, Carbazole Benzonitrile (donor-acceptor) derivatives, possess similar energy gap between singlet and triplet (∆EST, a key parameter in the RISC rate), but different TADF performance. In this sense, other parameter must be considered to explain these different behaviors. In this work, we theoretically investigate 2CzBN and 4CzBN and address the problem of how flexible donor-acceptor (D-A) or donor-acceptor-donor (D-A-D) molecular architectures affect the nature of excited state, and the oscillator strength. Furthermore, we analyze the RISC rates as a function of the conformation of the carbazole side groups, considering the S0, S1, T1 and T2 states. The oscillator strength of 4CzBN is higher than of 2CzBN, which, in turn, is almost vanishing, resulting in only 4CzBN being a TADF active molecule. We also note the presence of a second triplet state T2 lower in energy than S1, and that the reorganization energies, associated to the RISC processes involving T1 and T2, are both important factor in differentiating the rates in 2CzBN and 4CzBN. However, the 4CzBN RISC rate from T2 to S1 is surprisingly high with respect to the one from T1 to S1, although, according to EL-Sayed rules, since T2 (CT/LE) is more similar to S1 (CT) than in 2CzBN (LE, CT), this transition should be less favored. These insights are important to understand the photophysics of the TADF process and to design novel TADF emitters based on the benzo-carbazole architecture.

Computational characterization of carbazole-benzonitrile derivatives for applications in Organic Light Emitting Diodes

The technology of Organic Light-Emitting Diodes has reached such a high level of reliability that it can be used in various applications. The required light emission efficiency can be achieved by transforming the triplet excitons into singlet states through Reverse InterSystem Crossing (RISC), which is the main process of a general mechanism called thermally activated delayed fluorescence (TADF). In this thesis, we theoretically analyzed two carbazole-benzonitrile (donor-acceptor) derivatives, 2,5-di(9H-carbazol-9-yl)benzonitrile (p-2CzBN) and 2,3,4,5,6-penta(9H-carbazol-9-yl)benzonitrile (5CzBN), and addressed the problem of how donor-acceptor (D-A) or donor-acceptor-donor (D-A-D) flexible molecular architectures influence the nature of the excited states and the emission intensity. Furthermore, we analyzed the RISC rates as a function of the conformation of the carbazole lateral groups, considering the first electronic states, S0, S1, T1 and T2, involved in TADF process. The two prototype molecules, p-2CzBN and 5CzBN, have a similar energy gap between the first singlet and triplet states (∆EST, a key parameter in the RISC rate), but different TADF performances. Therefore, other parameters must be considered to explain their different behavior. The oscillator strength of p-2CzBN, never tested as emitter in OLEDs, is similar to that of 5CzBN, which is an active TADF molecule. We also note that the presence of a second T2 triplet state, lower in energy than S1 only in 5CzBN, and the reorganization energies, associated with RISC processes involving T1 and T2, are important factors in differentiating the rates in p-2CzBN and 5CzBN. For p-2CzBN, the RISC rate from T2 to S1 is surprisingly higher than that from T1 to S1, in disagreement with El-Sayed rules, due to a large reorganization energy associated to the T1 to S1, process; while the contrary occurs for 5CzBN. These insights are important for designing new TADF emitters based on the benzo-carbazole architecture.

Simulation of photoinduced processes in organic chromophores: mapping photochemically relevant states for accurate dynamics

The simulation of ultrafast photoinduced processes is a fundamental step towards the understanding of the underlying molecular mechanism and interpretation/prediction of experimental data. Performing a computer simulation of a complex photoinduced process is only possible introducing some approximations but, in order to obtain reliable results, the need to reduce the complexity must balance with the accuracy of the model, which should include all the relevant degrees of freedom and a quantitatively correct description of the electronic states involved in the process. This work presents new computational protocols and strategies for the parameterisation of accurate models for photochemical/photophysical processes based on state-of-the-art multiconfigurational wavefunction-based methods. The required ingredients for a dynamics simulation include potential energy surfaces (PESs) as well as electronic state couplings, which must be mapped across the wide range of geometries visited during the wavepacket/trajectory propagation. The developed procedures allow to obtain solid and extended databases reducing as much as possible the computational cost, thanks to, e.g., specific tuning of the level of theory for different PES regions and/or direct calculation of only the needed components of vectorial quantities (like gradients or nonadiabatic couplings). The presented approaches were applied to three case studies (azobenzene, pyrene, visual rhodopsin), all requiring an accurate parameterisation but for different reasons. The resulting models and simulations allowed to elucidate the mechanism and time scale of the internal conversion, reproducing or even predicting new transient experiments. The general applicability of the developed protocols to systems with different peculiarities and the possibility to parameterise different types of dynamics on an equal footing (classical vs purely quantum) prove that the developed procedures are flexible enough to be tailored for each specific system, and pave the way for exact quantum dynamics with multiple degrees of freedom.

Functional engineering of hybrid heterostructures for application in electronic, optical and optoelectronic nanostructured devices

Interfacing materials with different intrinsic chemical-physical characteristics allows for the generation of a new system with multifunctional features. Here, this original concept is implemented for tailoring the functional properties of bi-dimensional black phosphorus (2D bP or phosphorene) and organic light-emitting transistors (OLETs). Phosphorene is highly reactive under atmospheric conditions and its small-area/lab-scale deposition techniques have hampered the introduction of this material in real-world applications so far. The protection of 2D bP against the oxygen by means of functionalization with alkane molecules and pyrene derivatives, showed long-term stability with respect to the bare 2D bP by avoiding remarkable oxidation up to 6 months, paving the way towards ultra-sensitive oxygen chemo-sensors. A new approach of deposition-precipitation heterogeneous reaction was developed to decorate 2D bP with Au nanoparticles (NP)s, obtaining a “stabilizer-free” that may broaden the possible applications of the 2D bP/Au NPs interface in catalysis and biodiagnostics. Finally, 2D bP was deposited by electrospray technique, obtaining oxidized-phosphorous flakes as wide as hundreds of µm2 and providing for the first time a phosphorous-based bidimensional system responsive to electromechanical stimuli. The second part of the thesis focuses on the study of organic heterostructures in ambipolar OLET devices, intriguing optoelectronic devices that couple the micro-scaled light-emission with electrical switching. Initially, an ambipolar single-layer OLET based on a multifunctional organic semiconductor, is presented. The bias-depending light-emission shifted within the transistor channel, as expected in well-balanced ambipolar OLETs. However, the emitted optical power of the single layer-based device was unsatisfactory. To improve optoelectronic performance of the device, a multilayer organic architecture based on hole-transporting semiconductor, emissive donor-acceptor blend and electron-transporting semiconductor was optimized. We showed that the introduction of a suitable electron-injecting layer at the interface between the electron-transporting and light-emission layers may enable a ≈ 2× improvement of efficiency at reduced applied bias.