Dyes for inkjet printing are typically of the chromonic type. Chromonic mesophases have gained considerable attention as a well-defined group of lyotropic mesogens with different properties from conventional amphiphiles. While extensive research has been dedicated to the field of surfactant liquid crystals, structural and aggregation studies of chromonics have only emerged as a topic of interest within the last few years. The liquid crystalline structures in aqueous solutions of commercial Cu - phthalocyanine and black dyes have been examined using a combination of optical microscopy, UV-vis spectroscopy, nuclear magnetic resonance, wide- and small-angle X-ray diffraction and electronic paramagnetic resonance with a view to examining the phase behaviour of the chromonic mesophases formed over a broad range of concentrations and temperatures. These studies were performed in order to resolve outstanding problems concerning structural properties of these systems. Optical microscopy allowed us to identify the liquid crystalline phases and to construct the phase diagram. The observations show that both of these dyes form nematic mesophase above 15% wt / wt% dye. The small-angle diffraction data confirmed that the nematic phase for the black dye is maintained throughout the 16-25% composition range. A further increase in concentration leads to the formation of the hexagonal phase. The Cu – phthalocyanine dye also formed a nematic phase at low concentrations, with the aggregates undergoing a phase transition to an orientationally ordered chromonic liquid crystal phase at high dye concentration. These studies showed that this ordered phase possessed hexagonal symmetry. The wide-angle X-ray results demonstrated that aggregation involved π-π stacking of the molecules into columns. An additional reflection at ca. 6.8Å was observed for the black dye, which is believed to arise from “head – to – tail” packing of the molecules within the aggregates (a similar phenomenon observed in other azo dyes, e.g. Edicol Sunset Yellow).The densities of both dyes were measured over the studied range of concentrations. This enabled us to calculate the parameters of the aggregates within the hexagonal mesophase. A comparison between the area of the molecule and the cross-section of the aggregates showed that the aggregates of both dyes were the unimolecular stacks.

Este trabalho é dividido em duas partes. Na primeira parte são estudadas moléculas isoladas, na segunda, moléculas em meio solvente. Em sua primeira parte, métodos de mecânica quântica de alto nível de correlação são utilizados para caracterizar o estado fundamental da molécula de CaC. Propriedades elétricas e óticas desta molécula, como também da molécula de MgH, são obtidas usando-se o método de campo finito. O estudo dessas moléculas é de interesse para a Astrofísica. A segunda parte deste trabalho foca o estudo teórico do solvatocromismo da molécula de 4-[(4-dimethylamino)phenyl)imino]-2, 5-cyclohexadien-1-one, ou DIA (Dimethylaminoindoaniline). Esta molécula apresenta também uma grande variação da sua primeira hiperpolarizabilidade medida em solução. Sabe-se que ela existe em solução como uma combinação de duas formas extremas: a forma com separação de cargas eno e a forma neutra ceto. Após otimizarmos teoricamente as estruturas dessas duas formas, realizamos uma simulação Monte Carlo em um número de moléculas de solventes polares e apoiares. A análise da estrutura do solvente, em torno de cada soluto, é realizada usando-se funções de distribuição radial de pares. É feita, também, a análise das pontes de hidrogênio para cada estrutura eno ou ceto. Estruturas supermoleculares, envolvendo o soluto com as moléculas mais próximas e, em separado. com as moléculas ligadas por pontes de hidrogênio, são usadas como entrada para cálculos semi-empíricos de mecânica quântica da primeira transição eletrônica de absorção e da primeira hiperpolarizabilidade. Apenas superestruturas estatisticamente descorrelacionadas foram usadas no cálculo. Os resultados são analisados e comparados com resultados experimentais em solução e com resultados teóricos em fase gasosa. Todas as interpretações sugerem que a estrutura eno é responsável pelos espectros experimentais de absorção UV-visível, tanto em solvente polares quanto em apoiares. A estrutura eno tem também uma primeira hiperpolarizabilidade calculada que concorda adequadamente com aquelas observadas em alguns solventes. Para clorofórmio a primeira hiperpolarizabilidade do DIA é dez vezes maior que em outros solventes. / This work is divided in two parts. In the first part isolated molecules are studied, in the second part the interest is in molecules in solvent media. In the first part of this work, high level quantum mechanical correlation methods are employed to characterise the ground state of the CaC molecule. Electrical and optical properlies of this molecule and also of the MgH molecule are obtained using the finite field method. The study of these molecules is of interest to Astrophysics. The second part of this work focuses on the theoretical study of the solvatochromism of the 4-[(4-dimelhylamino)phenyl)imino]-2, 5-cyclohexadien-1-one molecule, or DIA (Dimethylaminoindoaniline). This molecule also presents a large variation of its measured first hyperpolarizability in solution. It is known that in solution this molecule exists in a combination of two extreme forms, the chargeseparated eno form and the neutral kelo form. After these two structures are theoretically optimised, a Monte Carlo simulation is performed in a number of polar and non-polar solvent molecules. Analysis of1 the solvent structure around each solute is performed using radial distribution function. Hydrogen bonding analysis for each eno or keto structure is also carried out. Supermolecular structures involving the solute and the nearest solvent molecules and, separately, the hydrogen bonded molecules, are used as input to quantum mechanical semi-empirical calculations of the first electronic absorption transition and the first hyperpolarizability. Only statistically non-correlated superstructures were used in the calculation. The results are analysed and compared to experimental results in solution and theoretical results in gas-phase. All interpretations suggest that the eno structure is responsible for the experimental UV-Visible absorption spectrum, both in polar and non-polar solvents. The eno structure has also a calculated first hyperpolarizability that agrees well with that observed for some solvents. For chloroform the first hyperpolarizability of DIA is ten times greater than in other solvents.

A class of linear diamidines was synthesized for the evaluation as a treatment of Human African Trypanosomiasis. These fused heterocyclic compounds are thiazole[5,4-d]thiazoles and are of interest because the parent compound, 2,5-Bis(4-amidinophenyl)-thiazolo[5,4-d]thiazole HCl salt, which is also called DB 1929, has exhibited a low nanomolar IC50 value against Trypanosoma brucei rhodesiense and has shown selectivity for binding to the human telomere G-quadruplex over that of DNA duplex. A fluoro and a methoxy derivative have been synthesized and are currently undergoing testing for activity and binding affinity. In addition, fluorescence studies of selected diamidines were done to study the effect of structural variation on fluorescence. This data is useful since it can determine what types of moieties are needed to yield a compound that will fluoresce in the higher wavelengths (500 nm and above) of the visible spectrum, which would be advantageous in determining the uptake of the drug in the trypanosome within the endemic areas of Africa with a simple microscope.

[pt] Os sistemas de administração controlada de medicamentos (drug delivery) permitem a introdução de uma substância terapêutica no organismo e melhoram sua eficácia e segurança, controlando a taxa, o tempo e o local de liberação, o que diminui os efeitos colaterais.Nesse trabalho nos dedicamos a estudar dois possíveis sistemas de administração de fármacos: lipossomos associados a surfactantes, já bastante utilizados em farmacologia, e nanobastões de ouro, cujas propriedades únicas têm sido avaliadas em aplicações biomédicas. Os lipossomos têm-se destacado devido a sua estabilidade e baixa toxicidade, os surfactantes são tensoativos muito usados tanto em farmacologia como para estabilizar soluções coloidais de nanopartículas. Já os nanobastões de ouro têm perspectivas promissoras para utilização em entrega de fármacos devido a suas propriedades óticas e biocompatibilidade. Estudamos, por meio de espectrofotometria de fluorescência e de absorção UV-visível, a associação entre esses sistemas e uma classe de fármacos denominada fluorquinolonas, que são antibióticos de amplo espectro bacteriano. A norfloxacina (NFX), pertencente à segunda geração de fluorquinolonas, foi escolhida para esse trabalho por ser naturalmente fluorescente, o que facilita a análise das interações sem a introdução de sondas extrínsecas ao sistema. Segundo a literatura, a associação da NFX com íons metálicos produz modificações nas propriedades desse fármaco, como solubilidade e biodisponibilidade. Essas mudanças têm sido avaliadas como uma possível solução ao problema de resistência bacteriana a antibióticos. Esse trabalho foi dividido em duas partes: na primeira, estudamos a formação dos complexos ternários de NFX com cobre-fenantrolina em presença de lipossomos associados a surfactantes que modificam a distribuição de carga elétrica superficial desses sistemas; na segunda parte estudamos a associação de NFX a nanobastões de ouro estabilizados por diferentes surfactantes. / [en] Drug delivery systems allow the introduction of a therapeutic substance into the body and improve its effectiveness and safety by controlling the rate, time and place of release, which reduces side effects. In this work, we study two possible drug delivery systems: liposomes associated with surfactants, which are already widely used in pharmacology, and gold nanorods, whose unique properties have been evaluated in biomedical applications. Liposomes have been remarkable because of their stability and low toxicity, and surfactants are widely used both in pharmacology and to stabilize colloidal solutions of nanoparticles. On the other hand, gold nanorods have promising perspectives for use in drug delivery due to their optical properties and biocompatibility.We study the association between these systems and a class of drugs called fluoroquinolones, which are broadspectrum bacterial antibiotics, using fluorescence spectrophotometry and UVvisible absorption. Norfloxacin (NFX), a second generation fluoroquinolone, was chosen because it is naturally fluorescent, which facilitates the analysis of interactions without the introduction of extrinsic probes into the system. According to the literature, the association of NFX with metal ions produces changes in the properties of this drug, such as solubility and bioavailability. These changes have been evaluated as a possible solution to the problem of bacterial resistance to antibiotics. This work was divided in two parts: first, we studied the formation of the ternary complexes of NFX with copper-phenanthroline in the presence of liposomes associated to surfactants that modify the distribution of surface electric charge of the systems; in the second part, we studied the association of NFX to gold nanorods stabilized by different surfactants.

Este trabalho é dividido em duas partes. Na primeira parte são estudadas moléculas isoladas, na segunda, moléculas em meio solvente. Em sua primeira parte, métodos de mecânica quântica de alto nível de correlação são utilizados para caracterizar o estado fundamental da molécula de CaC. Propriedades elétricas e óticas desta molécula, como também da molécula de MgH, são obtidas usando-se o método de campo finito. O estudo dessas moléculas é de interesse para a Astrofísica. A segunda parte deste trabalho foca o estudo teórico do solvatocromismo da molécula de 4-[(4-dimethylamino)phenyl)imino]-2, 5-cyclohexadien-1-one, ou DIA (Dimethylaminoindoaniline). Esta molécula apresenta também uma grande variação da sua primeira hiperpolarizabilidade medida em solução. Sabe-se que ela existe em solução como uma combinação de duas formas extremas: a forma com separação de cargas eno e a forma neutra ceto. Após otimizarmos teoricamente as estruturas dessas duas formas, realizamos uma simulação Monte Carlo em um número de moléculas de solventes polares e apoiares. A análise da estrutura do solvente, em torno de cada soluto, é realizada usando-se funções de distribuição radial de pares. É feita, também, a análise das pontes de hidrogênio para cada estrutura eno ou ceto. Estruturas supermoleculares, envolvendo o soluto com as moléculas mais próximas e, em separado. com as moléculas ligadas por pontes de hidrogênio, são usadas como entrada para cálculos semi-empíricos de mecânica quântica da primeira transição eletrônica de absorção e da primeira hiperpolarizabilidade. Apenas superestruturas estatisticamente descorrelacionadas foram usadas no cálculo. Os resultados são analisados e comparados com resultados experimentais em solução e com resultados teóricos em fase gasosa. Todas as interpretações sugerem que a estrutura eno é responsável pelos espectros experimentais de absorção UV-visível, tanto em solvente polares quanto em apoiares. A estrutura eno tem também uma primeira hiperpolarizabilidade calculada que concorda adequadamente com aquelas observadas em alguns solventes. Para clorofórmio a primeira hiperpolarizabilidade do DIA é dez vezes maior que em outros solventes. / This work is divided in two parts. In the first part isolated molecules are studied, in the second part the interest is in molecules in solvent media. In the first part of this work, high level quantum mechanical correlation methods are employed to characterise the ground state of the CaC molecule. Electrical and optical properlies of this molecule and also of the MgH molecule are obtained using the finite field method. The study of these molecules is of interest to Astrophysics. The second part of this work focuses on the theoretical study of the solvatochromism of the 4-[(4-dimelhylamino)phenyl)imino]-2, 5-cyclohexadien-1-one molecule, or DIA (Dimethylaminoindoaniline). This molecule also presents a large variation of its measured first hyperpolarizability in solution. It is known that in solution this molecule exists in a combination of two extreme forms, the chargeseparated eno form and the neutral kelo form. After these two structures are theoretically optimised, a Monte Carlo simulation is performed in a number of polar and non-polar solvent molecules. Analysis of1 the solvent structure around each solute is performed using radial distribution function. Hydrogen bonding analysis for each eno or keto structure is also carried out. Supermolecular structures involving the solute and the nearest solvent molecules and, separately, the hydrogen bonded molecules, are used as input to quantum mechanical semi-empirical calculations of the first electronic absorption transition and the first hyperpolarizability. Only statistically non-correlated superstructures were used in the calculation. The results are analysed and compared to experimental results in solution and theoretical results in gas-phase. All interpretations suggest that the eno structure is responsible for the experimental UV-Visible absorption spectrum, both in polar and non-polar solvents. The eno structure has also a calculated first hyperpolarizability that agrees well with that observed for some solvents. For chloroform the first hyperpolarizability of DIA is ten times greater than in other solvents.

L'imprégnation, étape cruciale de la préparation de catalyseurs supportés pour l’hydrotraitement de coupes pétrolières (CoMo / y-Al2O3) , a été étudiée dans ce travail. L'objectif principal a été de déterminer les phénomènes physico-chimiques et les interactions entre la surface du support et les espèces en solution se produisant pendant cette étape puis faire le lien avec l'activité du catalyseur final.La formation directe et la stabilité de la solution (3 Co2+ ; H4Co2Mo10O386-) ont été étudiées de manière poussée en fonction du pH, de la concentration, du rapport Co/Mo. Cela a nécessité le développement de méthodes analytiques quantitatives (spectrométries Raman et UV-visible), réalisées via SIMPLISMA, un algorithme de traitement des données par analyses factorielles. L'étude de l'imprégnation de la solution (3 Co2+ ; H4Co2Mo10O386-) sur y-Al2O3 a mené à une meilleure compréhension de cette étape. Il a été montré que la conservation de cette espèce sur le support dépend principalement de la densité en atomes de Mo / nm², mais également du rapport Co/Mo et du pH initial de la solution d’imprégnation, tous ces paramètres étant liés entre eux. Cette étude a mis en évidence le rôle majeur du support, via ses propriétés surfaciques.L’intérêt d’utiliser (3 Co2+ ; H4Co2Mo10O386-) pour préparer de tels catalyseurs réside dans la proximité du cobalt et du molybdène. La phase active résultante est très bien dispersée et hautement promue, et ce même si le précurseur est décomposé sur le support lors de l’imprégnation. Enfin, la méthodologie développée au cours de ce travail est transposable à la préparation de tout type de catalyseur supporté. / Impregnation, crucial step of the preparation of supported catalysts used for hydrotreatment of petroleum fractions (CoMo / gamma-alumina), has been studied in this work. The main aim has consisted in determining the physico-chemical phenomena and the interactions between the support surface and the aqueous species during this step, and then linking these results to the activity of the final catalyst.The direct formation and stability of the (3 Co2+ ; H4Co2Mo10O386-) solution have been studied as a function of pH, concentration and Co/Mo ratio. This has required the developement of analytical quantitative methods (Raman and UV-visible spectroscopies) carried out thanks to SIMPLISMA, an algorithm of data treatment by factorial analysis. The study of impregnating (3 Co2+ ; H4Co2Mo10O386-) solutions onto gamma alumina has led to a best understanding of this step. It was showed that the conservation of these species on the support mainly depends on the surface density of molybdenum atoms per square nanometer, but also on the Co/Mo ratio and the initial pH of impregnating solutions, all these parameters being linked together. This study has underlined the major role of the surface properties of the support. The interest of using (3 Co2+ ; H4Co2Mo10O386-) solutions to prepare such catalysts lies in the proximity of cobalt and molybdenum. The resulting active phase is very well dispersed and highly promoted, even if the precursor is decomposed on the support during impregnation. Finally, the methodology developed in this work is transferable to the preparation of any supported catalyst.

No description available.

Les matériaux à base de vanadium sont largement utilisés comme catalyseurs pour l'oxydation de composés organiques. Les propriétés catalytiques des catalyseurs au vanadium pour l'oxydation dépendent de l'état et de la stabilité des espèces de vanadium. Dans cette étude, nous développons des nouveaux catalyseurs hétérogènes au vanadium pour la réaction d’oxydation.Dans la première partie du travail, les matériaux mésoporeux à base de silice (MCM-41) contenant du Al (III) et du Ti (IV) sont envisagés comme supports. L'effet d'ancrage chimique de ces hétéroatomes sur les ions V (V) et leur dispersion dans la silice MCM- 41 ont été étudiés à l'aide d'une analyse quantitative des spectres UV-visible de réflectance diffuse. En complément, les matériaux ont été caractérisés par diffraction des rayons X (DRX), mesure de sorption d’azote, spectroscopie de résonance magnétique électrique (RPE) et la spectroscopie Raman. Les spectres UV-visible des échantillons hydratés et déshydratés mettent en évidence la coexistence de plusieurs espèces V (V) de différente nucléarité et différent taux d'hydratation. Le décalage vers le bleu de la bande UV des échantillons contenant comme des additifs les ions Al(III) ou Ti(IV) est cohérent avec une meilleure dispersion des ions vanadium présentant entre autres plus d’espèces mononucléaires (isolées). L'effet bénéfique du titane sur la dispersion de vanadium est compatible avec la formation directe de ponts covalents de type Ti-O-V.Dans la seconde partie, les ions V(IV) ont été déposés sur des matériaux mésoporeux à base de silice en utilisant une nouvelle stratégie dite de pochoir moléculaire ou « Molecular-Stencil Patterning ». La stratégie de pochoir moléculaire s’applique à la silice contenant des tensioactifs ioniques en utilisant ces derniers comme agent de masquage lors du greffage covalent de diverses fonctions. Cette stratégie de surface moléculaire permet de contrôler à la fois le voisinage moléculaire et la dispersion à longue distance des espèces de vanadium entre elles. La caractérisation a été effectuée en utilisant plusieurs méthodes telles l’analyse thermogravimétrique (ATG), la spectroscopie de résonance magnétique nucléaire (RMN), la spectroscopie infrarouge (IR) et la spectroscopie UV-visible. L'incorporation des ions titane (IV) joue le rôle d’ancre chimique pour les ions V(IV) comme dans le chapitre précédent. Il est montré qu’une proportion de V/Ti inférieure à un et proche de trois génère les meilleures conditions pour éviter la formation de gros agrégats d’oxyde de vanadium.Enfin, ces nouveaux matériaux au vanadium ont été testés en phase liquide pour catalyser l'oxydation partielle du cyclohexane en une huile désignée par son rapport molaire K/A de cyclohexanone (K) et de cyclohexanol (A). Ce mélange est utilisé comme telle en chimie industrielle de base, an particulier comme précurseurs de l'acide adipique et de caprolactame pour la synthèse du nylon. Les tests ont démontré que l’introduction de titane combiné à la stratégie de pochoir moléculaire a notablement amélioré les propriétés catalytiques de ce type de catalyseurs au vanadium.En conclusion, la silice MCM-41 au vanadium a été conçu par l’introduction des hétéroatomes d'ancrage et de la stratégie de pochoir moléculaire, afin d'améliorer la dispersion et la stabilité des sites actifs. Les matériaux conçus ont montré de meilleures propriétés et caractéristiques catalytiques dans divers caractérisation et la réaction d'oxydation. / Vanadium-based materials are widely used as catalysts for oxidation of organic compounds. The catalytic properties of vanadium catalysts for oxidation are related closely to the state and the stability of vanadium species. Therefore, a series of vanadium-containing MCM-41 silica were designed and developed in this study, and their catalytic application for oxidation reactions was evaluated as well.In the first part of work, the chemical anchoring effect of Al(III) or Ti(IV) heteroatoms on the dispersion of V (V) in MCM-41 type silica was investigated using a quantitative analysis of diffuse reflectance UV-visible spectra. The characteristic properties of prepared materials were determined by various characterization such as X-ray diffraction (XRD), N2 sorption measurement, Electron paramagnetic resonance (EPR) spectroscopy, UV-visible spectroscopy and Raman spectroscopy. UV-visible spectra of hydrated and dehydrated samples evidenced the coexistence of several V(V) species of different oligomerization and hydration levels. The global blue shift of the band in the presence of Al(III) or Ti(IV) additives was then assigned to a higher proportion of less clustered and isolated V(V) species. The stronger beneficial effect of Ti on the vanadium dispersion is consistent with a higher stability of the X-O-V bridges moving from X = Si to X = Al and Ti. In the second part, new mesoporous silica materials containing vanadium species were synthesized according to the molecular stencil patterning technique. Molecular stencil patterning is developed specifically for silica templated with ionic surfactants used as masking agent to sequentially immobilize via covalent bonding (grafting) different functions. This molecular surface engineering was proved to improve the vanadium species dispersion according to Thermogravimetric Analysis (TGA), Nuclear Magnetic Resonance spectroscopy (NMR), Infrared spectroscopy (IR) and UV-visible spectroscopy. The incorporation of titanium species played again the role to immobilize the vanadium species as the results in previous work. The V/Ti ratio should be less than 1 to control the formation of clusters of vanadium species.Lastly, the vanadium-containing materials were applied to the liquid phase oxidation of cyclohexane into cyclohexanol (A) and cyclohexanone (K). A mixture of these two products is often called K/A oil in the industrial chemical production. K/A oil is widely used as a raw material for adipic acid and caprolactam in the nylon industry. The catalysis results proved that the modification by adding titanium chemical anchors combined with the MSP technique improve the catalytic properties of vanadium-containing heterogeneous catalysts.In conclusion, the dispersion and stability of vanadium active sites has been improved in new syntheses of vanadium-containing MCM-41 type silica by combining both anchoring heteroatoms and molecular stencil patterning techniques. Such a novel design leads to better catalytic performance in oxidation reaction in correlation with the structural and physical characteristics of the material.

No description available.

Les carbones amorphes hydrogénés (a–C:H ou HAC) constituent une composante importante de la poussière interstellaire. Ces grains hydrocarbonés sont observés au travers de bandes d’absorption IR à 3.4, 6.9 et 7.3 microns, caractéristiques des vibrations des liaisons C-H aliphatiques. Leurs signatures spectrales sont détectées dans le milieu interstellaire diffus de différentes lignes de visée de la Voie Lactée, mais aussi de nombreuses autres galaxies. Cette thèse porte sur l’étude de ces a–C:H interstellaires, à la fois au travers d’observations de ces poussières, et grâce à la synthèse et la caractérisation d’analogues de laboratoire.Une première partie de mon travail de thèse est consacrée à l’observation de la bande à 3.4 microns des a–C:H du milieu interstellaire diffus galactique en direction de la source IRAS 18511+0146. La bande d’absorption des modes d’élongation C-H détectée dans cette direction, vers différentes lignes de visée proches les unes des autres, présente des profondeurs optiques similaires et les plus fortes observées dans la Voie Lactée en dehors du centre galactique. Différentes interprétations de la profonde bande dans cette direction sont discutées.Des analogues de ces poussières carbonées aliphatiques ont été synthétisés en laboratoire, sous forme de films, grâce à un plasma, et reproduisent bien les bandes IR observées dans le milieu interstellaire diffus. Ces échantillons ont été caractérisés par spectroscopie d’absorption dans l’UV-visible et l’IR.Puisque les a–C:H émettent un rayonnement visible après absorption de photons UV ou visibles, une partie de la thèse est consacrée à une étude systématique de cette photoluminescence. Pour la première fois, les rendements absolus et intrinsèques de photoluminescence d’a–C:H sont déterminés pour une large gamme de longueurs d’onde d’excitation. Les propriétés de la photoluminescence des a–C:H sont confrontées aux observations de l’Emission Rouge Etendue, une large bande d’émission interstellaire dont les porteurs ne sont pas identifiés.Afin de déduire l’influence des rayons cosmiques sur ces poussières carbonées, les analogues produits ont été irradiés par différents ions énergétiques dont le dépôt d’énergie est similaire à celui du rayonnement cosmique interstellaire. Les effets induits ont été suivies par IR. L’analyse de la déshydrogénation des a–C:H observée au travers de la disparition progressive des bandes des C-H aliphatiques permet de déduire l’évolution de ces poussières interstellaires et de leurs signatures spectrales sous l’effet des rayons cosmiques. La destruction induite par les rayons cosmiques est comparée aux effets de l’exposition aux photons UV et aux atomes d’hydrogène afin d’interpréter l’évolution de la bande d’absorption à 3.4 microns observée dans le milieu interstellaire diffus, mais pas dans les nuages denses. / The hydrogenated amorphous carbons (a–C:H or HAC) are an important component of interstellar dust. These hydrocarbon grains are observed through IR absorption bands at 3.4, 6.9 and 7.3 microns, due to aliphatic C-H bond vibrations. Their spectral signatures are detected in the diffuse interstellar medium along several sight lines in the Milky Way and in many external galaxies. This thesis deals with the study of such interstellar a–C:H, both through their astrophysical observation and the synthesis and characterisation of laboratory analogues.A first part of this PhD work concerns the 3.4 microns band observation in the galactic diffuse interstellar medium in the direction of IRAS 18511+0146 source. The C-H stretching mode absorption band detected toward several lines of sight of this cluster has the strongest optical depths observed in the Milky Way outside the galactic center. Different interpretations for this deep absorption band in this direction are discussed.Analogues of the amorphous carbonaceous dust component have been produced in the laboratory with a plasma source. Their IR spectra are in excellent agreement with the absorption bands observed in the diffuse interstellar medium. The samples have been characterised by UV-visible and IR absorption spectroscopy.Since a–C:H emit a visible radiation when they absorb UV or visible photons, a systematic study of this photoluminescence is performed. For the first time, the absolute and intrinsic photoluminescence yield of a–C:H is measured for a broad range of excitation wavelengths. The photoluminescence properties of a–C:H is compared to observations of the Extended Red Emission, a large interstellar emission band whose carriers are not identified.To infer the influence of cosmic rays on this carbonaceous dust, the produced analogues have been irradiated by different swift ions, similar to interstellar cosmic rays. The induced modifications have been monitored by their IR spectrum. The a–C:H dehydrogenation is observed through the progressive disappearance of the aliphatic C-H bands. Its analysis allows us to deduce the evolution of the a–C:H dust and its spectral signatures under cosmic ray exposition. The destruction due to cosmic rays is compared to the effects induced by exposure to UV photons and hydrogen atoms, in order to interpret the evolution of the absorption band at 3.4 microns observed in the diffuse interstellar medium, but not in dense clouds.