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The exploitation of the relationship between the chemical and physical properties of materials is the hallmark of advancing science throughout the world. The basic understanding of how and why molecules react and interact with each other in different environments allows for the discovery and implementation of new materials and devices that not only advance the state of human life but continually change the planet. The work described in this dissertation generally falls under three diverse categories: functionalization of fullerenes, investigation of host/guest interactions in solution, and the synthesis and characterization of ion containing polymers. The separation and functionalization of fullerenes is a recent and exciting area of research. The separation methods outlined are intended to increase the availability of endohedral metallofullerenes by decreasing their cost of production. Functionalized fullerene species were achieved through Bingel and Prato reactions to provide materials with novel functional groups. These materials may be further utilized in photovoltaic or other organic electronic devices. The characterization of noncovalent interactions between different molecules in solution is the focus of supramolecular chemistry. Isothermal Titration Calorimetry stands out as one of the best, among the many methods used to elucidate the characteristics of these systems. The binding of bis- imidazolium and paraquat guests with macrocyclic host molecules has been explored in this work. The measurements of the association constants for these systems will aid in the ongoing synthesis of new host/guest systems. Ion containing polymers were synthesized and characterized for their use in electroactive devices. Imidazolium containing polymers with bulky anions were synthesized on low glass transition polymer chains. These materials had enhanced ion conductivity and may eventually be used in electronic actuator materials. / Ph. D.

L’objectif de ce travail de thèse a été de développer l’ingénierie des polymères liquides ioniques(PILs) de type imidazolium ainsi qu’une nouvelle famille de copolymères à blocs apparentés.Des PILs type imidazolium ont été utilisés en tant que polymères réactifs pour la catalyse organique etla modification chimique par post-polymérisation. Divers composés (homopolymères, copolymèresstatistiques de type styrénique, polymères réticulés) stables à l'air, portant divers contre-anions (bromures,hydrogénocarbonates, carboxylates), ont été spécialement conçus via des stratégies de synthèserelativement simples. La génération de carbènes N-hétérocycliques supportés sur polymères (poly(NHC)s)a permis de comparer les performances catalytiques de tous ces précurseurs à travers des réactions deréférence de la catalyse organique. Spécifiquement, les copolymères statistiques type styrénique peuventégalement être fonctionnalisés de manière stoechiométrique par post-polymérisation avec différentssubstrats électrophiles (e.g. CS2, isothiocyanate, métaux de transition).Une nouvelle famille de copolymère à blocs contenant un bloc poly(acétate de vinyle) et un bloc detype poly(bromure de N-vinyl-3-alkylimidazolium), a été synthétisé par CMRP. La capacité de cescomposés à s'auto-assembler en diverses mésostructures en masse comme en solution a ensuite étédémontrée. Des mesures de conductivité ionique ont montré l’influence de la préparation des échantillonset des conditions de mesures sur les valeurs obtenues. Le comportement en solution par la réactivité ioniquedu bloc PIL et la modification chimique du bloc hydrophobe poly(acétate de vinyle) en hydrophilepoly(alcool vinylique) ont permis la formation de différentes nanostructures micellaires.Mots clés : Polymères liquides ioniques, Copolymères à blocs, Imidazolium, catalyse organique,Modification post-polymérisation, Auto-assemblage, Conductivité ionique, nanoparticules d’or. / The aim of this PhD work is to expand the scope of engineered imidazolium-based poly(ionicliquid)s (PILs) and their related PIL-block copolymers (PIL BCPs).The use of the imidazolium-based PILs as true reactive polymers for organocatalysis and post-chemicalmodification is first described. Miscellaneous air-stable PIL derivatives featuring various counter-anions(e.g. bromides, hydrogen carbonates, carboxylates), including homopolymers, statistical copolymers ofstyrenic-type and crosslinked copolymer networks have been specifically designed by relatively simplesynthetic strategies. The generation of related polymer-supported N-heterocyclic carbenes, poly(NHC)s,enables comparing the catalytic performances in selected organocatalyzed reactions. Specific polystyrenebasedcoPILs can be also stoichiometrically derivatized by post-chemical modification using variouselectrophilic substrates (e.g. CS2, isothiocyanate, transition metals).A novel family of imidazolium-based PIL BCPs, namely poly(vinyl acetate)-b-poly(N-vinyl-3-alkylimidazolium bromide)s synthesized by CMRP, is then described. The ability of these compounds toself-assemble into various types of mesostructures in bulk or in solution has been demonstrated. Ionicconductivity measurements evidenced the influence of sample preparation and measurement conditions.The behavior in solution evidenced via the ionic responsiveness of the PIL block but also by post-chemicalmodification of the hydrophobic poly(vinyl acetate) block into hydrophilic poly(vinyl alcohol) theformation of various micelle-like nanostructures.Keywords: Poly(ionic liquid)s, Block copolymers, Imidazolium, Organocatalysis, Post-polymerizationmodification, Self-assembly, Ionic conductivity, Gold nanoparticles / El objetivo de esta tesis fue el desarrollo de polímeros de ingeniería iónicoslíquidos (pils) y tipo imidazolio una nueva familia de copolímeros de bloques relacionados.Lager tipo imidazolio fueron utilizados como reactivos para la catálisis orgánica ymodificación química de polímeros después de la polimerización. Varios compuestos(homopolímeros, copolímeros aleatorios de tipo estireno, polímeros reticulados) estable en elaire, contra de la realización diversos aniones (bromuros, bicarbonatos, carboxilatos), hansido especialmente diseñadas utilizando estrategias de síntesis relativamente simple. Se utilizóla generación de carbenos N-heterocíclicos soportado sobre polímeros (poli (NHC) s) paracomparar el rendimiento catalítico de estos precursores de referencia a través de reacciones decatálisis orgánica. Específicamente, los copolímeros de tipo estireno también se puedenfuncionalizar sustratos por polimerización posterior estequiométricamente con diferenteselectrófilos (por ejemplo, metales CS2, isotiocianato, de transición).Una nueva familia de copolímero de bloque que contiene un poli (acetato de vinilo) y unbloque de poli (bromuro de N-vinil-3-alquilimidazolio) se sintetizó en CMRP. La capacidadde estos compuestos a auto-ensamblan en varias mesoestructuras como entonces se demostrósolución en masa. Mediciones de conductividad iónica han demostrado la influencia de lascondiciones de preparación y medición de la muestra en los valores obtenidos. Elcomportamiento en solución por el bloque PIL reactividad de iones, y la modificaciónquímica del bloque hidrófobo de poli (acetato de vinilo) hidrófilo poli (alcohol vinílico)permitió la formación de nanoestructuras diferentes micelares.Palabras clave: polímeros líquidos iónicos, copolímeros de bloque, imidazolio, catálisisorgánica, Cambiar post-polimerización, auto-ensamblaje, conductividad iónica, lasnanopartículas de oro.

Ce mémoire est consacré à l’utilisation de l’électrochimie comme outil de synthèse alternatif pour la formation de nouvelles molécules de la famille des azoliums. Une nouvelle méthode de synthèse électrochimique a été mise au point pour la synthèse de carboxylates d’imidazoliums (carbènes masqués) conduisant à une grande variété de molécules. Cette méthode a été comparée aux synthèses chimiques déjà existantes. Dans un contexte actuel de développement durable, des produits bio sourcés ont été synthétisés et à partir de ces derniers l’optimisation du procédé a été réalisée afin de réduire les flux entrants et sortants de matière et d’énergie.Le rôle clé de l’ion hydrogénoxalate a été démontré dans la synthèse de liquides ioniques et/ou sels d’imidazoliums. Certains ont été par la suite employés comme catalyseurs recyclables pour l’estérification de Fischer.La réduction électrochimique directe de différents azoliums a aussi été étudiée. Le couplage des radicaux neutres ainsi électrogénérés conduit aux σ-dimères correspondant. Ce produit redonnant par oxydation l’azolium de départ, la renversabilité de la réaction a été prouvée ouvrant la voie à de nouveaux interrupteurs moléculaires.Une électrosynthèse d’azoliums à fragment aromatique a également été étudiée. Ainsi, l’oxydation électrochimique du pyrène en présence de différents nucléophiles azotés génère les sels d’azoliums pyrène. Ce procédé a été optimisé en termes de réduction de déchets et de simplification de mise en œuvre. Certaines molécules obtenues ont montré des propriétés antimicrobiennes. / This work deals with the use of electrochemistry as a tool for alternative synthesis of new azolium-based molecules.A new electrosynthesis method was developed for the synthesis of imidazolium carboxylates (masked carbenes) leading to a wide library of compounds. This approach was compared to already reported chemical syntheses. In the current context of sustainable development, bio based products have been synthesized and optimization of the process was achieved in order to reduce waste and energy consumption.The key role of the hydrogenoxalate anion was demonstrated in the synthesis of ionic liquids and/or imidazolium salts. Some of them were employed as recyclable catalysts for Fischer esterification.The direct electrochemical reduction of various azoliums was also studied. The coupling of two electrogenerated neutral radicals leads to the corresponding σ-dimers. The oxidation of this species gives back the starting azolium proving the “reversibility” of the reaction, paving the way for new molecular switches.Azolium containing pyrene moiety was also electrosynthesized. Thus, electrochemical oxidation of pyrene in presence of different nitrogen nucleophiles leads to azolium pyrenes. This process was optimized in order to reduce waste and simplify the experimental setup. Some products have shown antimicrobial activities.

Nature has always remained a constant source of inspiration for chemists for synthesizing natural products, mimicking enzymatic reactions or to construct molecular architectures resembling biological assemblies. With the rapid growth of ‘Supramolecular Chemistry’ along with the advancement of the synthetic methodologies, molecular systems with brand new complexities have been synthesized, alongside the efficacy of weak, reversible non-covalent interactions have also been extensively explored. A number of such forces including hydrogen bonding, solvophobic effect, dynamic covalent interactions and metal-ligand coordination have been exploited to assemble the molecular building blocks and stitch them together to construct discrete ‘self-assembled’ architectures integrated with desired functionalities. Metal-ligand coordination driven self-assembly certainly evolved as one of the most successful approaches for the construction of discrete supramolecular architectures during last two and half decades. The high directionality and reversible nature of certain metal-ligand bonds allow the pre-designing of sophisticated architectures which can be successfully obtained by ‘error corrections’ via a thermodynamically controlled self-assembly process. Numerous aesthetically elegant two dimensional (2D) and three dimensional (3D) metallosupramolecular architectures have been constructed which have been studied for various potential applications including guest encapsulation, catalysis, sensing, optoelectronics, drug delivery, protection of reactive species etc. Construction of such molecular architectures uses symmetric and rigid building blocks which strictly preserves their geometrical coding and thus finally determines the fate of the self-assembly. Pyridyl-based donors have been extensively used due to their well-behaved coordination with transition metal ions. Interestingly, imidazole based donors remained almost unexplored for such purpose mainly due to the rotational flexibility of imidazole moieties owing to the lack of -electron delocalization with the aromatic backbone, which makes pre-designing an architecture extremely difficult. However, this unpredictability can lead to the formation of unprecedented molecular architectures. Furthermore, the conventional rigid ‘acceptors’ used in the ‘directional bonding approach’ always results in the formation of rigid assemblies, which cannot be utilized for the construction of smart molecular machine based applications. In this context, incorporation of restricted rigidity in the building blocks can be a convenient approach to construct versatile and flexible supramolecular architectures. Although flexible donors are quite common in coordination-driven self-assembly, the use of flexible metal acceptor is scarcely Highly symmetric spherical assemblies of square planer Pd(II) and Pt(II) ions are one of the most extensively studied metallosupramolecular architectures owing to their topological similarity with the spherical virus capsids. Unfortunately, none of the reported molecular spheres are soluble in water which restricts their applications in aqueous media. On the other hand, most of the metallosupramolecular architectures cannot be used for redox based applications as the oxidation state of the associated metal ions must be kept unaltered. Although, assemblies constructed mainly by the ferrocene containing acceptors are shown to be exhibiting redox property, the donor inherited redox active metallosupramolecular systems are extremely rare. Discrete 3D metallosupramolecular cages have been extensively studied as synthetic hosts where the hydrophobic pockets have been utilized as safe shelter for reactive species, for catalyzing chemical transformations, tuning electronic and optical properties of guest molecules, as delivery vehicle for drug molecules etc. However, a major drawback of many such 3D cages is associated with their closed-shell topology, where the large cavities are accessible though relatively much smaller apertures which prevent larger guest molecules to enter inside. So, an interesting finding in this field would be to construct molecular hosts with larger apertures. Picric acid (PA) is a strong organic acid and like many other polynitroaromatic compounds, it is a powerful explosive. In addition, it has large scale industrial application for the synthesis of dyes and pharmaceuticals. However, PA has potential health hazards and it is a water pollutant owing to its high aqueous solubility. Thus, the development of selective receptors which can efficiently interact with PA and detect it at very lower concentration is an appealing field of research. Chapter 1 briefly discusses the history of supramolecular chemistry and the concept of ‘self-assembly’ along with the several synthetic methodologies for the construction of discrete supramolecular architectures. It also includes a brief discussion on the various design approaches to construct 2D and 3D molecular architectures by metal-ligand coordination which is followed by an account on some of the important applications of such metallosupramolecular architectures. At the end, a small introduction on the fluorescence-based detection techniques for PA has also been included. Chapter 2A accounts for the exploration of two linearly substituted benzene bisimidazole donors L1 and L2 for coordination-driven self-assembly. L1 and L2 possesses different ‘natural’ donor angles as the imidazole moieties in L2 are twisted heavily with respect to the phenyl plane due to the steric hindrance exerted by the methyl groups. Interestingly, while the self-assembly of L1 with [cis-(tmeda)Pd(NO3)2] (tmeda = N,N,Nꞌ,Nꞌ-tetramethylethane-1,2-diamine) exclusively formed a [3+3] molecular triangle, the self-assembly of L2 yielded a [4+4] molecular square as the major product with the same acceptor. In addition, similar treatment with the analogous Pt(II) acceptor resulted mixtures of [3+3] and [4+4] assemblies in both cases; however, the [3+3] assembly was the major product in case of L2. These contradictory product distributions in case of L2 with analogous Pd(II) and Pt(II) acceptors could be corroborated by the delicate balance between the entropic and enthalpic contributions. Scheme 1. Self-assembly of L1/L2 with [cis-(tmeda)Pd(NO3)2] and [cis-(tmeda)Pt(NO3)2], respectively. Furthermore, the reactions of L1 and L2 with a 0º bisplatinum acceptor, viz. AntPt yielded the expected [2+2] macrocycles (8 and 9), respectively. However, the interesting observations Scheme 2. Self-assemblies of L1 and L2 with the 0º bisplatinum acceptor AntPt. obtained from the variable temperature NMR studies suggested the existence of a mixture of inter-convertible conformational isomeric structures of 9. Chapter 2B describes the synthesis of a novel semi-rigid bisplatinum acceptor bisPt-NO3 based on benzil backbone for the construction of flexible metallamacrocycles. The benzil group was selected due to its unique rotational flexibility along the benzyl C-C bond which can generate a wide range of bite angles to make it compatible with the variety of donors of diverse shapes and sizes. The acceptor was successfully self-assembled with four different bisimidazole donors (L1-L4) to yield corresponding [2+2] metallamacrocycles (M1-M4) which were characterized by multinuclear NMR and ESI-MS spectrometry; and their structures were elucidated by semi-empirical geometry optimizations. Scheme 3. Self-assembly of [2+2] metallamacrocycles M1-M4 by a semi-rigid bisplatinum acceptor bisPt-NO3. Chapter 3 discusses the synthesis of the very first example of a water soluble molecular sphere MC-1 by the self-assembly of square planar Pd(II) ions with a flexible cationic tritopic donor La(NO3)3 containing 4,4-bispyridyl arms. The structural flexibility of La(NO3)3 makes it capable of binding with metal ions in its syn- or anti-conformations which was also experimentally observed in the structures of the three newly synthesized coordination polymers, viz. Ag-CP, Zn-CP and Cd-CP constructed by using La(NO3)3 as (co)ligand. Finally, the 4:3 self-assembly of [La(NO3)3] and Pd(NO3)2 in aqueous media produced the desired M6L8 type Scheme 4. Self-assembly of the water soluble molecular dice MC-1 from the tricationic tritopic donor La(NO3)3. molecular sphere- MC-1, which contain 36+ overall charges. The compound could be easily solubilized in water after isolation as solid by simple stirring at room temperature. Single crystal X-ray diffraction analysis (SCXRD) revealed the ‘dice’-shaped architecture of MC-1 where the eight faces are occupied by the coordinated Pd2+ ions and the bispyridyl arms and the vertices are occupied by mesityl moieties. MC-1 is stable in aqueous media, however disintegrates in DMSO, as observed by variable temperature NMR experiments. In addition, MC-1 also produced ligand inherited redox signals in cyclic voltammetry experiments. Chapter 4 describes the synthesis of a novel non-symmetric tetraimidazole donor L based on carbazole backbone. The complexity of the donor is associated with the allowed free rotation of the imidazole moieties along with the non-symmetric nature of the carbazole backbone which make L a very unusual donor for coordination-driven self-assembly. The crystal structure of L showed that the presence of the N-Me group caused a greater twisting of the nearby imidazole moieties with respect to the other set of imidazole moieties. The self-assembly of L with [cis-(en)Pd(NO3)2] (en = ethane-1,2-diamine) yielded a mixture of M4L8 and M6L12 type self-assembled products, as evidenced from the ESI-MS spectrometry. However, the DOSY NMR spectra of the product showed a single diffusion coefficient for all the peaks, indicating that both type of assemblies have similar size and hence suggested the formation of a tetrafacial barrel and a cubic architecture. A similar self-assembly of L with [cis-(tmeda)Pd(NO3)2] also produced a water soluble product. ESI-MS spectra in this case only confirmed the formation of a M4L8 assembly- MB-1. SCXRD analysis of the coronene encapsulated complex of MB-1 gave more insights on the sophisticated non-symmetric tetrafacial barrel architecture of MB-1 with large Scheme 5. Construction of the water soluble molecular barrel MB-1 by the self-assembly of a non-symmetric tetraimidazole donor L. rectangular apertures. The centrosymmetric molecule can encapsulate two aromatic guest molecules inside its hydrophobic cavity and was found to be efficiently encapsulating polyaromatic hydrocarbons (PAHs) in aqueous media. In addition, MB-1 has been successfully exploited to carry water insoluble perylene molecule inside HeLa cells for fluorescence imaging purpose without showing significant toxicity. L also formed a water insoluble tetrafacial barrel (MB-2) by self-assembly with [cis-(dppf)Pd(OTf)] (dppf=diphenylphosphino ferrocene) which interestingly has a symmetrical architecture, as evidenced from the SCXRD analysis. The formation of the symmetrical barrel is driven by the steric hindrance between the bulky phenyl groups of the nearby dppf moieties. Chapter 5 reports the study of interactions between picric acid (PA) with a few newly synthesized fluorescent imidazolium salts (S1-S3). The fluorescence titration study of the positively charged receptors with PA showed rapid decrease of the corresponding fluorescence intensities upon gradual addition of PA. The Stern-Volmer plots suggested the involvement of both static and dynamic quenching mechanisms which was further supported by fluorescence lifetime measurements, NMR and UV-Vis spectroscopic analyses. The values of the Stern-Volmer constants (Ksv) reflected strong receptor-PA binding. The quenching efficiency calculations in the presence of several other analytes proved that the receptors are highly selective for PA in both aqueous and non-aqueous media. The mode of interactions in solid state was investigated by the crystal structure analysis of the [S1PA] complex. 1H NMR spectra of the same complex indicated strong interaction between the imidazolium moieties of the receptor Scheme 6. The fluorescent imidazolium salts based receptors S1-S3 and the florescence titration plot for S1 with PA. Inset: the solutions of S1 and (S1+PA) in DMSO under UV light. with PA in solution; however, no significant interaction of PA with the anthracene moieties was observed in solution as we well as in the solid state. Also the quenching efficiencies and the Ksv values were correlated with the positive charge(s) present on the receptors with the help of two newly synthesized mono-positive receptors S4 and S5.

La synthèse de matériaux zéolithiques est régie par de nombreux paramètres, en particulier la nature de l'hétéroélément associé au silicium et celle de l'agent organique structurant. Ainsi, l'introduction de germanium dans les milieux réactionnels ainsi que l'utilisation de structurants dérivés d'imidazole, les cations 1-éthyl-3-méthylimidazolium et 1-butyl-3-méthylimidazolium, ont permis la découverte de deux nouveaux solides microporeux nommés respectivement IM-16 et IM-20 et présentant des topologies de charpente inédites (respectivement UOS et UWY). De plus, un troisième germanosilicate poreux nommé IM-17 a été obtenu en présence du cation décaméthonium. Chacun de ces trois matériaux possède un système tridimensionnel de canaux avec des ouvertures de 8 et 10 atomes T (IM-16) ou de 10 et 12 atomes T (IM-17 et IM-20), ainsi que des unités de construction composites d4r au sein de leur charpente. Enfin, une partie importante du travail a été consacrée à l'élaboration de molécules structurantes originales (dérivés du décahydro-dicyclopenta[b,d]pyrrole) puis de leur emploi en synthèse hydrothermale. Ces essais ont permis d'obtenir divers matériaux déjà connus, parmi lesquels les zéolithes IM-12 (UTL), ITQ-7 (ISV), ITQ-17 (BEC) et ITQ-21. / The synthesis of zeolitic materials is ruled by numerous parameters, particularly the nature of the heteroelement associated with silicon and of the organic structure-directing agent (SDA). The introduction of germanium into the synthesis gels and the use of imidazole-derived SDAs, the cations 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium, allowed us to discover two new microporous solids named IM-16 and IM-20 and exhibiting novel framework structures (respectively UOS and UWY). Furthermore, a third porous germanosilicate named IM-17 was obtained in the presence of the decamethonium cation. Each of these materials possesses a three-dimensional channel system with 8- and 10-ring pores (IM-16) or 10- and 12-ring pores (IM-17 and IM-20), as well as double-4-ring (d4r) composite building units in their framework. Finally, an important part of this work was dedicated to the elaboration of original SDAs (decahydro-dicyclopenta[b,d]pyrrole derivatives) and their use in hydrothermal synthesis. This led to the synthesis of several known zeolites such as IM-12 (UTL), ITQ-7 (ISV), ITQ-17 (BEC) and ITQ-21.

No description available.

Este trabalho visa a síntese e estudo das propriedades ópticas de uma série de complexos tetrakis(β-dicetonatos) de terras raras (TR3+) com alta intensidade de luminescência, tanto na forma sólida quando dissolvidos em líquidos iônicos a base de imidazólio. Nesta síntese dos complexos [Cnmim][TR(TTA)4] (TR: Gd3+ e Eu3+) foram utilizados o ligante tenoiltrifluoroacetonato (TTA–) e os contracátions 1-alquil-3-metilimidazólio ([Cnmim]+), variando o comprimento da cadeia alquílica do imidazólio de três a oito átomos de carbono. Também foram sintetizados os líquidos iônicos brometo de 1-alquil-3-metil-imidazólio [Cnmim]Br, com a cadeia alquílica variando de três até oito. Os compostos foram caracterizados pelas técnicas de análise elementar de CHN, espectroscopia vibracional na região do infravermelho, ressonância magnética nuclear de próton, análise térmica, e difração de raios X pelo método de pó. Os complexos preparados tiveram as suas propriedades ópticas estudadas, tanto no estado sólido como em soluções dos líquidos iônicos [Cnmim]Br correspondentes, utilizando espectroscopia fotoluminescente por meio dos espectros de excitação e de emissão, espectro de emissão resolvido no tempo, e curvas de decaimento luminescentes. Os espectros de absorção no infravermelho mostraram que o ligante TTA– atua como um quelato. Por meio dos dados espectrais de fosforescência dos complexos [Cnmim][Gd(TTA)4] foi possível estudar a as posições dos estados excitados singleto (S) e tripleto (T) do ligante TTA–. Observou-se que as bandas alargadas de absorção, oriundas dos estados excitados singleto e tripleto do ligante, são ligeiramente deslocadas para regiões de maior energia com o aumento do tamanho da cadeia alquílica do contracátion imidazólio. Ademais, a posição do estado T1 do ligante TTA encontra-se em energia maior do que o nível emissor 5D0 do Eu3+, sendo assim possível a transferência intramolecular de energia ligante→Eu3+. Os complexos [Cnmim][Eu(TTA)4] apresentaram luminescência intensa na cor vermelha, proveniente do íon európio trivalente, tanto no estado sólido quanto em soluções de líquidos iônicos, proveniente das transições 5D0→7F0-4. Os espectros de excitação dos complexos em cada um dos casos mostraram que a transferência de energia do ligante TTA– para o íon Eu3+ é bastante eficiente. Também, foi observado que os espectros de excitação dos complexos em soluções de líquidos iônicos exibiram o mesmo perfil espectral. Os desdobramentos dos níveis de energia 7F0-4 permitiram inferir que sítio de simetria do Eu3+ se aproxima de C4v no caso dos complexos [C5mim][Eu(TTA)4], [C6mim][Eu(TTA)4], e [C7mim][Eu(TTA)4], ao passo que o sítio de simetria se aproxima de C2v no caso dos complexos [C3mim][Eu(TTA)4], [C4mim][Eu(TTA)4], e [C8mim][Eu(TTA)4]. Observou-se que todos os seis complexos [Cnmim][Eu(TTA)4] em soluções de líquidos iônicos [Cnmim]Br correspondentes apresentam espectros de emissão com o mesmo perfil espectral. Este resultado indicou que todos estes complexos assumem a mesma forma em solução. Os complexos apresentaram altos valores do parâmetro intensidade experimental Ω2 tanto no estado sólido quanto em solução, refletem a alta intensidade da transição 5D0→7F2 quando comparada com a intensidade da transição 5D0→7F1. Os valores dos parâmetros Ω4 dos complexos em solução de líquidos iônicos são semelhantes, evidenciando que existe uma pequena mudança de estrutura do complexo do estado sólido para solução. Os sistemas preparados neste trabalho apresentam alta eficiência quântica, em torno de 75%. Tal resultado mostra o potencial destes sistemas de terras raras para a aplicação em dispositivos moleculares conversores de luz (DMCLs). / The aim of this work was to study the optical properties of a new series of rare earth (RE3+) tetrakis(β-diketonates) complexes with high luminescence intensity, both in solid state and when dissolved in imidazolium-based ionic liquids. The [Cnmim][RE(TTA)4] (RE: Gd3+ e Eu3+) complexes were prepared by using the ligand thenoyltrifluoroacetonate (TTA–) and the countercations 1-alkyl-3-methylimidazolium ([Cnmim]+), varying the length of the alkyl chain at the imidazolium from three to eight carbon atoms. Besides, all the ionic liquids 1-alkyl-3-methyl-imidazolium bromide ([Cnmim]Br) were also synthesized and discussed. The RE3+ coordination compounds were characterized by the techniques of CHN elemental analysis, infrared absorption spectroscopy, proton nuclear magnetic resonance, thermal analysis, and X-ray powder diffraction. The synthetized complexes had their optical properties studied, both in the solid state and in solutions of the corresponding ionic liquids [Cnmim]Br, using photoluminescence spectroscopy of excitation and emission, time resolved emission spectra, and luminescence decay curves. The infrared absorption spectroscopy showed that the TTA– ligand act as a bidentate chelate ligand. Based on the phosphorescence spectral data of the complexes [Cnmim][Gd(TTA)4], it was possible to determine the singlet (S) and triplet (T) excited states positions of the TTA– ligand. The broad absorption bands from the singlet and triplet excited states of the ligand are slightly shifted to higher energy as increases the alkyl chain size of the imidazolium countercation. In addition, the T1 state position of the TTA ligand is at higher energy than the 5D0 emitting level of the Eu3+, thus allowing the intramolecular energy transfer ligand-Eu3+. The [Cnmim][Eu(TTA)4] complexes showed a high intense red-colored luminescence from the trivalent europium ion, both in the solid state and in solutions of ionic liquids, originating from the 5D0→7F0-4 transitions. The excitation spectra of the complexes in each case showed that the transfer of energy from the TTA– ligand to the Eu3+ ion is very efficient. It was observed that the excitation spectra of the complexes in solutions of ionic liquids exhibited the same spectral profile. The 7F0-4 energy level splitting suggests that the Eu3+ ion is situated in a symmetry site close to a C4v for the complexes [Cnmim][Eu(TTA)4] with n = 5, 6 and 7. On the other hand, the complexes with values of n = 3, 4 e 8 the Eu3+ ion is situated in a symmetry site close to C2v. It was also observed that all the six [Cnmim][Eu(TTA)4] complexes in solutions of the corresponding [Cnmim]Br ionic liquids have the same emission spectral profiles, indicating that the Eu3+ ion are in the same chemical environment. The complexes presented high values for the experimental intensity parameter Φ2 in both solid and solution states, showing the high intensity of the 5D0→7F2 transition when compared to the intensity of the 5D0→7F1 transition. The Ω4 values of the complexes in solution of ionic liquids are similar, suggesting that there is a small change of structure of the complex from the solid state to the solution. The Eu3+ coordination compounds have high emission quantum efficiencies (~ 75%). This result shows a great potential of these europium systems for application as light-converting molecular devices (LMDCs).