por fatores químicos e físicos, promovendo infecções hospitalares relacionadas ao uso de cateteres e demais instrumentos hospitalares, elevando os índices de mortalidade e morbidade de pacientes. Portanto, garantir a correta desinfecção capaz de impedir contaminações e infecções em ambientes hospitalares é de extrema importância. Para este fim, neste estudo explorou-se a seleção de uma substância capaz de marcar e ser biocida contra biofilmes fúngicos em superfícies de aço inox, a partir de nove candidatos benzimidazóis fluorescentes, com códigos NB1 a NB9 e oito sais imidazólicos de corantes azóicos, denominados C4MImErioCr, C10MImMO, C16MImMO, (C10)2MImMO, C4MImMO, C10MImORANGEII, C16MImORANGEII e (C10)2MImORANGEII. Desenvolveu-se para este fim um roteiro metodológico para determinar quais destas substancias são capazes de marcar e eliminar biofilmes de forma eficaz e segura. Os métodos utilizados para avaliar as substâncias foram (1) a Concentração Mínima Inibitória (MIC) conforme protocolo do CLSI M27-A3, (2) microscopias verificando capacidade das substâncias em marcar células, (3) ensaios com deposição sobre superfície do corpo de prova (placas de aço inox) com biofilme, (4) verificação da atividade biocida sobre biofilmes utilizando microscopias e (5) ensaios de citotoxicidade. Essas substâncias foram testadas frente a nove cepas de Candida spp., incluindo C. tropicalis, C. albicans e C. parapsilosis Na avaliação das substâncias, SI de corantes azóicos inibiram o crescimento celular de fungos, já o benzimidazol fluorescente NB7 apresentou atividades simultâneas de detecção e ação biocida sobre o biofilme. Todas as cepas testadas foram sensíveis a essa substância. Além disso, os biofilmes formados pelas cepas ATCC 18804 (C. albicans,) ATCC 22019 (C. parapsilosis) e ATCC 750 (C. tropicalis) na superfície de aço inox 304 sofreram ação biocida, quando expostas por 15 segundos a NB7, sendo um potencial sanitizante. / Biofilms provide an environment capable of protecting microbial cells from damage by chemical and physical factors of the immune system, and hinder the penetration of various antimicrobial agents, promoting nosocomial infections related to catheters, increasing mortality and morbidity of patients. Therefore, it is important to ensure proper hygiene to prevent contamination and infections in hospital environments. For this purpose, this study explored the identification of a substance that both detects and have biocide activity against fungal biofilms on stainless steel surfaces. Both nine fluorescent benzimidazole substances, coded NB1 to NB9 and eight imidazolium salts of azo dyes, named denominados C4MImErioCr, C10MImMO, C16MImMO, (C10)2MImMO, C4MImMO, C10MImORANGEII, C16MImORANGEII e (C10)2MImORANGEII were tested as candidates. These substances were tested applying a methodology developed to determine if a substance is able detecting and have biocide activity against fungal biofilms. Overall, this study involved the following methods: (1) Minimum Inhibitory concentration test following the CLSI protocol (M27-A3; the substances were tested against nine fungal strains, including C. tropicalis, C. albicans and C. parapsilosis.), (2) microscopy to determine the marker capacity, (3) spraying tests of the substances on surfaces (stainless steel) with fungal biofilms, (4) tests to verify the capability of the substances to both stain and were biocide against fungal biofilms, applying microscopic techniques and (5) cytotoxicity tests Within the set of seventeen substances, benzimidazole derivative NB7 was identified with the desired capabilities, staining and biocide activity against fungal biofilms at the same time. All tested fungal strains were sensible to this substance. A biocide activity was identified on the biofilms of ATCC 18804 (C. albicans), ATCC 22019 (C. parapsilosis) and ATCC 750 (C .tropicalis), grown on stainless steel 304, when exposed fifteen seconds to substance NB7. Although this substance showed being cytotoxic, it represents a promising candidate for sanitization purposes, including medical tools.

Les liquides ioniques à base d’imidazolium présentent une plateforme architecturale unique aisément fonctionnalisable permettant de préparer des matériaux ioniques avec des propriétés mésomorphes. Dans le but d’introduire des propriétés supplémentaires, nous avons élaboré des composés à coeur rigide étendu. La stratégie de synthèse adoptée passe par un couplage de type Ullmann. Nous avons développé une méthodologie nécessitant uniquement du Cuivre (II) supporté sur zéolithe (Na-Y) et du carbonate de potassium. Cette approche a pour avantage d’éviter l’utilisation de solvant, d’atmosphère inerte et de ligands. Ce couplage a été optimisé en utilisant la technique de synthèse en micro-ondes (réduction du temps de réaction, diminution des sous-produits formés). Après avoir étudié cette méthodologie, nous l’avons étendu à d’autres propriétés notamment à des matériaux (scintillateurs) présentant des propriétés de détection et de discrimination des rayonnements neutrons/gamma en introduisant des chromophores au sein de nos composés. Le couplage de type Ullmann utilisé a également permis d’élaborer des composés pouvant présenter des propriétés électroniques (conduction et électrochromisme). / Ionic liquids based on imidazolium are an excellent platform that can be designed to promote liquid crystalline phases. In order to introduce additional properties, we synthesized compounds with a rigid expanded core. Herein, we reported an Ullmann-type coupling using only Cu(II)-NaY as catalyst and potassium carbonate as base. This synthetic approach avoids the use of solvents, inert atmosphere and ligands. We have optimized this coupling using the technique of microwave synthesis (reduction of reaction time and by-products formed). After studying this methodology, we have extended it to other behaviors. Thus we have synthesized ionic materials (scintillators) with properties of detection and discrimination of radiation neutrons/gamma by introducing chromophores in our compounds. This Ullmann-type coupling has allowed to prepare compounds that can have electronic properties (conduction and electrochromism).

In this thesis, the physical properties of certain multi-functional organic crystals were studied in detail. This study involves the growth of single crystals of Glucuronic acidγ-lactone (GAL), Imidazoliumtartarate (IMLT), (Bis)imidazoliumtartarate (BIMLT), and Diisopropylammonium iodide (DPI) and investigations of their optical, dielectric, piezoelectric, pyroelectric, and ferroelectric properties as a function of temperature and dependence on crystal structure in these organic crystals. Piezoelectric resonance was observed at certain frequencies when dielectric constant was monitored along the b-plate of GAL crystals. The electro-mechanical coupling coefficient estimated at the resonance near 1 MHz frequency revealed an exceptionally large value in GAL similar to that in inorganic lead titanate. The dependence of the piezoelectric resonance frequency on temperature was studied in detail. These crystals showed excellent second- and third-order nonlinear optical properties as well as high laser damage threshold. The high values of χ(2) andχ(3), laser damage threshold, and low UV cut-off makes GAL crystals an interesting prospect for NLO and laser applications. Towards this goal, GAL crystals were studied in detail with regard to determination of directions of dielectric axes, optic axes, and collinear phase-matching. Single crystals of another promising NLO organic crystal, IMLT were also grown which showed interesting dielectric, piezoelectric, and NLO properties. The dielectric dispersion with temperature provided an insight to the polarization mechanisms. Like GAL, IMLT also exhibits piezoelectric resonance. The existence of only one easy axis of vibration in IMLT enabled the candidate to identify the first resonance peak as corresponding to the fundamental mode of oscillation in the sample. This also helped to determine many piezoelectric parameters. By angular phase matching, one direction of phase matching in IMLT was identified. The conversion efficiency of IMLT along this direction was determined which was high in comparison to that in a standard KDP crystal. At piezoelectric resonance frequencies, the electro-optic response due to photo-elastic contributions is enhanced. Single crystals of organic ferroelectric BIMLT were grown by mixing two moles of imidazole with one mole of l-tartaric acid. The controversy with regard to the phase transition temperature of BIMLT was clarified by the DSC and structural analysis in this work. Previously, studies on BIMLT were limited to polycrystalline samples and single crystals with inclusions primarily due to the difficulty in growing good quality single crystals from aqueous solution. However, by experimenting the growth process using different solvents, good quality single crystals were achieved without the trapping of mother solution. This remarkable find is a notable result in these crystals for ferroelectric applications. The mechanism of ferroelectricity in BIMLT is mainly attributed to the transfer of protons along N–H---O hydrogen bonds in the direction of b-axis. Interestingly, the values of spontaneous polarization and Curie-temperature in the organic ferroelectric material DPI were significantly high and comparable to several popular inorganic ferroelectrics. The polarization obtained in this material is the highest among reported organic ferroelectrics. In addition to the high Curie temperature and spontaneous polarization, there were unique phase transitions that were revealed in DPI. The mechanism of ferroelectricity is quite complex, mainly being displacive type on account of the change in orientation of dipoles with electric field. Some contribution to ferroelectricity comes from the order-disorder nature of Nitrogen atom.

por fatores químicos e físicos, promovendo infecções hospitalares relacionadas ao uso de cateteres e demais instrumentos hospitalares, elevando os índices de mortalidade e morbidade de pacientes. Portanto, garantir a correta desinfecção capaz de impedir contaminações e infecções em ambientes hospitalares é de extrema importância. Para este fim, neste estudo explorou-se a seleção de uma substância capaz de marcar e ser biocida contra biofilmes fúngicos em superfícies de aço inox, a partir de nove candidatos benzimidazóis fluorescentes, com códigos NB1 a NB9 e oito sais imidazólicos de corantes azóicos, denominados C4MImErioCr, C10MImMO, C16MImMO, (C10)2MImMO, C4MImMO, C10MImORANGEII, C16MImORANGEII e (C10)2MImORANGEII. Desenvolveu-se para este fim um roteiro metodológico para determinar quais destas substancias são capazes de marcar e eliminar biofilmes de forma eficaz e segura. Os métodos utilizados para avaliar as substâncias foram (1) a Concentração Mínima Inibitória (MIC) conforme protocolo do CLSI M27-A3, (2) microscopias verificando capacidade das substâncias em marcar células, (3) ensaios com deposição sobre superfície do corpo de prova (placas de aço inox) com biofilme, (4) verificação da atividade biocida sobre biofilmes utilizando microscopias e (5) ensaios de citotoxicidade. Essas substâncias foram testadas frente a nove cepas de Candida spp., incluindo C. tropicalis, C. albicans e C. parapsilosis Na avaliação das substâncias, SI de corantes azóicos inibiram o crescimento celular de fungos, já o benzimidazol fluorescente NB7 apresentou atividades simultâneas de detecção e ação biocida sobre o biofilme. Todas as cepas testadas foram sensíveis a essa substância. Além disso, os biofilmes formados pelas cepas ATCC 18804 (C. albicans,) ATCC 22019 (C. parapsilosis) e ATCC 750 (C. tropicalis) na superfície de aço inox 304 sofreram ação biocida, quando expostas por 15 segundos a NB7, sendo um potencial sanitizante. / Biofilms provide an environment capable of protecting microbial cells from damage by chemical and physical factors of the immune system, and hinder the penetration of various antimicrobial agents, promoting nosocomial infections related to catheters, increasing mortality and morbidity of patients. Therefore, it is important to ensure proper hygiene to prevent contamination and infections in hospital environments. For this purpose, this study explored the identification of a substance that both detects and have biocide activity against fungal biofilms on stainless steel surfaces. Both nine fluorescent benzimidazole substances, coded NB1 to NB9 and eight imidazolium salts of azo dyes, named denominados C4MImErioCr, C10MImMO, C16MImMO, (C10)2MImMO, C4MImMO, C10MImORANGEII, C16MImORANGEII e (C10)2MImORANGEII were tested as candidates. These substances were tested applying a methodology developed to determine if a substance is able detecting and have biocide activity against fungal biofilms. Overall, this study involved the following methods: (1) Minimum Inhibitory concentration test following the CLSI protocol (M27-A3; the substances were tested against nine fungal strains, including C. tropicalis, C. albicans and C. parapsilosis.), (2) microscopy to determine the marker capacity, (3) spraying tests of the substances on surfaces (stainless steel) with fungal biofilms, (4) tests to verify the capability of the substances to both stain and were biocide against fungal biofilms, applying microscopic techniques and (5) cytotoxicity tests Within the set of seventeen substances, benzimidazole derivative NB7 was identified with the desired capabilities, staining and biocide activity against fungal biofilms at the same time. All tested fungal strains were sensible to this substance. A biocide activity was identified on the biofilms of ATCC 18804 (C. albicans), ATCC 22019 (C. parapsilosis) and ATCC 750 (C .tropicalis), grown on stainless steel 304, when exposed fifteen seconds to substance NB7. Although this substance showed being cytotoxic, it represents a promising candidate for sanitization purposes, including medical tools.

Líquidos iônicos imidazólios (LIIs) associados a ânions com caráter básico foram sintetizados, caracterizados e seu comportamento estudado em solução. Inicialmente a troca isotópica H/D preferencial no grupo C2-CH3 de sais de 1-nbutil-2,3-dimetilimidazólio (BMMI) foi avaliada. Ficou evidente que o contato entre os pares de íons e a atuação do ânion como uma base neutra influenciaram fortemente a deuteração. Após a análise dos resultados de RMN, cálculos de DFT (Teoria do Funcional de Densidade) e Difração de Raios X, um complexo entre uma molécula de água e alguns LI foi sugerido, modificando fortemente a estrutura organizacional e afetando também a troca isotópica nestes sais. Através do mecanismo reacional proposto, surgiu a possibilidade de deuteração de novos substratos contendo H ácidos, usando os LIIs como catalisadores. A reação de troca isotópica em alcinos e cetonas foi estudada e bons resultados foram obtidos. O efeito da variação de cátions e ânions na atividade catalítica foi analisado, assim como a variação dos substituintes dos substratos. Além disso, um estudo cinético foi realizado através de análises de RMN de 1H e o mecanismo reacional foi proposto. Por fim, a capacidade de formação de pares iônicos em soluções aquosas de LIIs foi avaliada na captura de CO2. Ótimos resultados foram obtidos e atribuídos à ocorrência de sorção física e química devido à ativação da água pelo LII. / Imidazolium based ionic liquids (ImIL) associated with basic anions were synthesized, characterized and studied. Initially the preferred H/D isotopic exchange to C2-CH3 group of 1-nbutyl-2,3-dimethylimidazolium salts (BMMI) was studied. In this context, it became evident that the ion-pairing formation and the anion action as a neutral base strongly influence the deuteration reaction. NMR analysis, theoretical calculation (Density Functional Theory) and X-ray Diffraction have been performed and a complex between a water molecule and the IL have been suggested, strongly modifying the IL structure and characteristics. The isotope exchange reaction in alkynes and ketones was studied using imidazolium based ionic liquids as catalysts and good results obtained. The effect of cation and anion variation on the catalyst activity were analyzed, also a variation of the substrate substituent’s. Also, a kinetic study was performed by 1H NMR analyzes and the reaction mechanism were proposed. Finally, the ability to form ion pair contact of ILs in aqueous solutions was evaluated for CO2 capture. Great results were obtained and this success can be attributed to the occurrence of physical and chemical sorption due to water activation by the IL.

Os métodos computacionais da química quântica foram empregados para estudar as estruturas moleculares e as energias de interação de cátions e ânions que são componentes de alguns líquidos iônicos funcionalizados, derivados do imidazólio. O estudo teve como objetivo comparar e relacionar os efeitos da presença de funcionalização nos substituintes das posições 1 e 3 do cátion imidazólio, nas propriedades desses líquidos iônicos. Essa funcionalização pode ocorrer pela presença de insaturações, grupos aromáticos, éteres, álcoois, tióis, aminas, nitrilas entre outros grupos nas cadeias dos substituintes. Nesta tese são reportados os estudos dos complexos formados por ânions tetrafluorborato e cátions imidazólio substituídos por grupos metila, etila, propila, butila, isobutila, vinila, propargila, alila, crotila e metalila, observando assim o efeito da presença de substituintes contendo cadeias insaturadas em comparação com os de cadeias saturadas nas estruturas, distribuições de carga, energias de interação e propriedades físico-químicas desses sistemas. Nesses sistemas foram observados intensos efeitos de polarização e transferência de carga ânion-cátion. Foram encontradas diversas relações entre volumes iônicos, energias de interação dos íons e as propriedades de transporte dos respectivos líquidos iônicos. / The methods of computational quantum chemistry have been used to study the molecular structures and the interaction energies of cations and anions which are components of some functionalized ionic liquids derived from imidazolium. The objective of this study is comparing and relating the effects of the presence of functionalization of the side chains of the imidazolium with the properties of these ionic liquids. This functionalization can occur by the presence of unsaturated side chains, aromatic groups, ether, alcohols, thiols, amines, nitriles among other groups in the side chains. In this thesis are reported the studies of the complexes formed of tetrafluorborate anions and imidazolium cations with side chains methyl, ethyl, propyl, butyl, isobutyl, vinyl, propargyl, allyl, crotyl and methallyl, thus observing the effects of the presence of unsaturated side chains compared to saturated ones on the structures, charge distributions, interaction energies and physicochemical properties of these systems. It was observed in these systems strong effects of polarization and anion-cation charge transfer. It was found several relations between ionic volumes, interation energies of the ions and the transport properties of the respective ionic liquids.

Os métodos computacionais da química quântica foram empregados para estudar as estruturas moleculares e as energias de interação de cátions e ânions que são componentes de alguns líquidos iônicos funcionalizados, derivados do imidazólio. O estudo teve como objetivo comparar e relacionar os efeitos da presença de funcionalização nos substituintes das posições 1 e 3 do cátion imidazólio, nas propriedades desses líquidos iônicos. Essa funcionalização pode ocorrer pela presença de insaturações, grupos aromáticos, éteres, álcoois, tióis, aminas, nitrilas entre outros grupos nas cadeias dos substituintes. Nesta tese são reportados os estudos dos complexos formados por ânions tetrafluorborato e cátions imidazólio substituídos por grupos metila, etila, propila, butila, isobutila, vinila, propargila, alila, crotila e metalila, observando assim o efeito da presença de substituintes contendo cadeias insaturadas em comparação com os de cadeias saturadas nas estruturas, distribuições de carga, energias de interação e propriedades físico-químicas desses sistemas. Nesses sistemas foram observados intensos efeitos de polarização e transferência de carga ânion-cátion. Foram encontradas diversas relações entre volumes iônicos, energias de interação dos íons e as propriedades de transporte dos respectivos líquidos iônicos. / The methods of computational quantum chemistry have been used to study the molecular structures and the interaction energies of cations and anions which are components of some functionalized ionic liquids derived from imidazolium. The objective of this study is comparing and relating the effects of the presence of functionalization of the side chains of the imidazolium with the properties of these ionic liquids. This functionalization can occur by the presence of unsaturated side chains, aromatic groups, ether, alcohols, thiols, amines, nitriles among other groups in the side chains. In this thesis are reported the studies of the complexes formed of tetrafluorborate anions and imidazolium cations with side chains methyl, ethyl, propyl, butyl, isobutyl, vinyl, propargyl, allyl, crotyl and methallyl, thus observing the effects of the presence of unsaturated side chains compared to saturated ones on the structures, charge distributions, interaction energies and physicochemical properties of these systems. It was observed in these systems strong effects of polarization and anion-cation charge transfer. It was found several relations between ionic volumes, interation energies of the ions and the transport properties of the respective ionic liquids.

A substituição da água por líquidos iônicos (LI) oferece uma alternativa promissora para o desenvolvimento de processos de separação de gases, principalmente devido à significativa demanda energética em processos convencionais que utilizam soluções aquosas de aminas. Esta proposta apresenta-se interessante por aliar as propriedades dos LI à reatividade de aminas perante o CO2. A físico-química que governa as interações entre os íons dos líquidos iônicos é bastante diversa das encontradas em solventes moleculares, sendo que ainda permanecem muitas questões fundamentais acerca destes materiais. A melhor compreensão das interações estabelecidas entre aminas e LI, e dos produtos formados após a reação com CO2, pode contribuir para o desenvolvimento de processos mais eficazes que permitam a substituição da água nos processos convencionais. O presente trabalho teve como objetivo investigar soluções das aminas primárias propilamina (PA), 2-metoxietilamina (MOEN) e monoetanolamina (MEA) em líquidos iônicos imidazólicos com diferentes ânions: 1-butil-3-metilimidazólio tetrafluoroborato (BMIBF4), hexafluorofosfato (BMIPF6), bis-(trifluorometilsulfonil)imida (BMITFSI) e dicianamida (BMIN(CN)2). Para tal, foram utilizadas as espectroscopias Raman e infravermelho (IR), cujos resultados foram suportados por cálculos baseados na teoria do funcional da densidade (DFT). Os resultados mostram que o modo de estiramento assimétrico do grupo NH2 das aminas, νas(NH2), é o mais adequado para se inferir sobre o grau de agregação das aminas em solventes orgânicos e em LI. No caso das reações das aminas com CO2 nos diferentes LI, o comportamento foi similar à reação com as aminas puras, ou seja, na PA houve cristalização, na MOEN, a formação de um líquido miscível com os LI, e na MEA, a formação de um gel com a subsequente separação de fases. Em particular, no caso da reação entre MEA e CO2 em LI, além da separação de fases, foi observada a diferente solubilidade dos produtos de reação dependendo do LI em questão. Em contraste ao processo convencional que utiliza soluções aquosas de aminas para a captura do CO2, acredita-se que a separação de fases observada em LI seja uma vantagem a ser explorada, já que permitiria um menor gasto energético na recuperação da amina absorvedora, além da recuperação do solvente não volátil / The replacement of water by ionic liquids (IL) offers a promising alternative for the development of gas separation processes, mainly due to the significant energy demand in conventional processes using aqueous solutions of amines. This proposal is exciting because it combines the properties of IL with the reactivity of amines towards CO2. The physical-chemistry that governs the interactions between the ionic liquids ions is quite different from those found in molecular solvents, and many fundamental questions still remain about these materials. A better understanding of the interactions between amines and IL, and the products formed after the reaction with CO2, may contribute to the development of more efficient processes to enable the replacement of water in conventional processes. This study aimed to investigate solutions of the primary amines propylamine (PA), 2-methoxyethylamine (MOEN) and monoethanolamine (MEA) in imidazolium ionic liquids with different anions: 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4), hexafluorophosphate (BMIPF6), bis (trifluoromethylsulfonyl)imide (BMITFSI) and dicyanamide (BMIN(CN)2). For these purposes, the Raman and infrared (IR) spectroscopies were used, whose results were supported by calculations based on density functional theory (DFT). The results show that the asymmetric stretching mode of the amines group NH2, νas(NH2), are the most suitable for inferring the degree of aggregation of amines in organic solvents and IL. In the case of reactions of amines with CO2 in different IL, the behavior was similar to the reactions with neat amines, that is, it was observed crystallization with PA, the formation of a liquid miscible with IL in MOEN, and the formation of a gel-like product with subsequent phase separation in MEA. In particular, the case of the reaction between MEA and CO2 in IL, in addition to the phase separation, it was observed the different solubility of the reaction products depending on the IL concerned. In contrast to the conventional process using aqueous solutions of amines for the capture of CO2, it is believed that the phase separation observed in IL is an advantage to be exploited, since they allow lower energy consumption in the recovery of the amine absorber, besides the recovery of the non-volatile solvent.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This paper presents the study of influence of molecular structure of ionic liquid-type Gemini imidazolium ìn the formation of aggregates in aqueous solution. The aggregation behavior was investigated through differential scanning calorimetry, conductivity, surface tension, fluorescence, dynamic light scattering techniques and transmission electron microscopy. Among the obtained data, it is possible to highlight the critical aggregation concentration (cac) determination, that is, a concentration range where a variation in physical and chemical properties of the solution emerging from the formation of aggregates can be observed. Differential scanning calorimetry showed that the aggregation can be detected by means of thermal events, characteristics of pure LI. Through the conductivity, it was possible to determine thermodynamic parameters, as the aggregate free energy (ΔG°a), the binding degree of the counterion to the aggregate (α), and the process equilibrium constant (Ka). Surface tension measurements provided data regarding the activity of the surfactant LI studied, while fluorescence, dynamic light scattering and transmission electron microscopy were important to obtain information on the aggregates' size. Critical packing parameter was determined throughout data obtained from X-ray diffraction and surface tension. This parameter allowed the prediction of LI micellar form currently in study. It was observed that the values of cac determined by the methods employed are consistent with each other and it was found that the increase of the carbon chain used as a spacer group promoted the aggregates formation, as well as caused an improvement in the surfactant LI properties. / Este trabalho apresenta o estudo da influência da estrutura molecular dos líquidos iônicos (LI) dicatiônicos derivados do imidazolíneo na formação de agregados em solução aquosa. O comportamento de agregação foi investigado pelas técnicas de calorimetria exploratória diferencial, condutividade, tensão superficial, fluorescência, espalhamento de luz dinâmico e microscopia eletrônica de transmissão. Dentre os dados obtidos, destaca-se a determinação da concentração de agregação crítica, que trata-se de uma faixa de concentração onde pode ser observado a variação nas propriedades físicas e químicas da solução emergente da formação de agregados. Por calorimetria exploratória diferencial observou-se que a agregação pode ser detectada por meio de eventos térmicos característicos dos LI puros. Através da condutividade foi possível determinar parâmetros termodinâmicos como a energia livre de agregação (ΔG°a), grau de ligação do contraíon ao agregado (α) e constante de equilíbrio do processo (Ka). As medidas de tensão superficial forneceram dados a respeito da atividade tensoativa dos LI em estudo enquanto que a fluorescência, espalhamento de luz dinâmico e microscopia eletrônica de transmissão foram importantes para obter informações a sobre o tamanho dos agregado. O parâmetro de empacotamento crítico foi determinado, para isto utilizou-se dados provenientes da difratometria de raios-X e tensão superficial. Este parâmetro possibilitou a previsão da forma micelar para os LI em estudo. Foi observado que os valores de cac determinados pelos métodos empregados são concordantes entre si e verificou-se que o aumento da cadeia carbônica utilizada como grupo espaçador tanto favoreceu a formação dos agregados como também provocou uma melhora nas propriedades tensoativas dos LI.

La résistance aux antibiotiques est l'une des menaces les plus graves pour la santé mondiale de nos jours. L'émergence de bactéries multirésistantes encourage les chercheurs à développer de nouveaux antibiotiques et stratégies pour compenser leurs différents mécanismes de résistance. L'un de ces mécanismes de défense est la formation de biofilms. Sous cette forme, les bactéries développent une matrice extracellulaire protectrice les rendant plus résistantes à divers traitements antimicrobiens. Nous avons conçu et synthétisé des composés de déstabilisation des membranes avec des caractéristiques clés : un cation benzimidazolium ou imidazolium, une chaîne apolaire hydrophobe et/ou un site de reconnaissance des anions lipophiles. Ces caractéristiques leur confèrent une activité antimicrobienne accrue et une grande capacité à perturber les membranes cellulaires. Ces composés perturbateurs de la membrane agissent via un mécanisme rapide et efficace et ont montré de bons résultats contre les souches de SARM (staphylococcus aureus résistant à la méthiciline) en tant que candidats antibiofilms prometteurs. Ces nouveaux agents ont le potentiel de se disperser et d'inhiber la formation de biofilms et pourraient avoir un impact positif sur la médecine humaine à l'avenir. / Antibiotic resistance is one of the most serious threats to global health nowadays. Emergence of resistant bacteria encourages researchers to develop new antibiotics and strategies to mitigate their different resistance mechanisms. One of these defense mechanisms is the formation of biofilms. In this form, bacteria develop a protective extracellular matrix making them more resistant to various antimicrobial treatments. We have designed and synthesized membrane destabilizing compounds with three key features: a benzimidazolium or an imidazolium cation, a hydrophobic apolar chain, and a lipophilic anion recognition site. These characteristics give these compounds increased antimicrobial activity and greater ability to disrupt cell membranes. These membrane-disrupting compounds act via a fast and efficient mechanism and showed good results against MRSA (methicillin-resistant staphylococcus aureus) strains as promising antibiofilms candidates. These new agents have the potential to disperse and inhibit the formation of biofilms and could have a positive impact on human medicine in the future.