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Luminescent complexes of lanthanide ions are of growing interest because the long lifetime of emission allows time-resolved detection procedures to be employed. A key step in the development of such systems lies in the preparation of highly luminescent complexes which display high stability in aqueous solution. A series of ligands based on 1,4,7,10-tetraazacyclododecane have been prepared, in which the nitrogen atoms are appended with coordinating phosphinate or amide groups, or a combination of both. The compounds obtained are octadentate ligands which form water-soluble lanthanide complexes of high stability. Complexes incorporating aryl groups in the pendent arms have been prepared and some display intense metal luminescence following excitation into the organic chromophores. A back energy transfer process occurs in the terbium complexes containing naphthyl or quinohnone groups. Measurements of the luminescence lifetimes in H(_2)O and H(_2)O show diat diere are no metal-bound water molecules in the tetrabenzylphosphinate complexes. Those incorporating one amide and three phosphinate groups display hydration states between 0 and 1. An attempt has been made to correlate this information with that obtained from an analysis of the nuclear magnetic resonance dispersion profiles of related gadolinium complexes. The complexes incorporating secondary amide groups display an additional deactivation pathway for the metal excited state involving energy transfer into N-H bonds. The luminescence behaviour of four macrocyclic tetraamide ligands incorporating naphthyl fluorophores has been studied. These compounds exhibit distinctive changes in luminescence in the presence of quenching (eg. Pb(^2+), Cu(^2+) and Ni(^2+)) and non- quenching ions (eg. Cd(^2+) and Zn(^2+)). This behaviour extends to non-aqueous solution. The protonated tetranaphthyl ligand forms an intramolecular excimer in which the excimer emission displays a sensitive dependence on the polarity of die solvent.

Contrast agents are used in over 35% of MRI scans today and their use is increasing as they become ever more sophisticated. The challenge for researchers in this field is to synthesise smart imaging agents, which can be addressed using more than one imaging modality. The ultimate goal of these types of contrast agents is to be able to increase the contrast between normal and diseased tissue with smaller amounts of the agent being administered. This thesis describes the synthesis of complexes that are designed to have increased hydration numbers and rapid solvent exchange. The key to designing clinically effective contrast agents of this type is to minimize the affinity the contrast agent for endogenous anions such as phosphate that can exclude water from the inner coordination sphere, inhibiting exchange and reducing the relaxivity. A hexaanionic ligand was synthesized by tri-alkylation of cyclen with the dimethyl ester of N-isophthaloylchloroacetamide and subsequent hydrolysis. Lanthanide complexes of the ester and acid form of the ligand were synthesized and were shown to be luminescent. Relaxometric and time-resolved studies were used to establish that phosphate binding is not significantly inhibited in the anionic complex, suggesting that proximate negative charge is essential to inhibition of anion binding. Lanthanide complexes of DO3P and a bisDO3P analogue containing a bipyridyl bridge were also prepared, and shown to be more effective at inhibiting phosphate binding, though their properties exhibit dependence on pH. The bipyridyl derivative was used to prepare rhenium containing d-f hybrid complexes. These exhibited luminescence from both the rhenium MLCT and the lanthanide, though sensitized emission from the ytterbium is inefficient as a consequence of poor spectral overlap, Routes towards preparation of ligands bearing pyridylphosphinate pendent arms have also been explored.

Nonlinear luminescence quenching has been documented in numerous systems such as organic crystals, rare earth insulators, laser materials, semiconductors, and phosphors. In each of these systems nonlinear luminescence quenching occurs under conditions of high excitation density from interactions between excited centers, the result is an additional nonradiative decay pathway that lowers luminescence quantum efficiency. During investigations into the spectra and dynamics of Eu2O3, an apparent saturation dip in the excitation spectra of nano-sized Eu2O3 particles was observed. This thesis describes the investigation into the nature of the saturation effect. The samples studied using luminescent spectroscopy included micron sized Eu2O3 crystals of both cubic and monoclinic phases, nanocrystal monoclinic Eu2O3, and a large fused crystal of monoclinic Eu2O3. It was determined that the saturation effect was due to nonlinear luminescence quenching occurring at the wavelengths of absorption maxima. The mechanism of nonlinear luminescence quenching was concluded to be upconversion by energy transfer. / Master of Science

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Le manuscrit porte sur l'étude de la combinaison entre les complexes des métaux du groupe 4 et les lanthanides métalliques.La première partie s'intéresse à la réduction des dichlorométallocènes du groupe 4 par les lanthanides. En fonction du lanthanide choisi, il est possible d'accéder à différents degrés d'oxydation du titane. La présence d'un excès de lanthanides permet la réduction des métallacyclopentadiènes issus de la dimérisation réductrice d'alcynes comportant des groupements aryles. La seconde partie concerne l'adaptation du système d'oléfination de groupements carbonyles mis au point par Takeda. Le choix du système Cp2TiCl2/Dy, sans phosphite, permet la conversion de nombreux composés carbonylés en alcènes avec pour certains une bonne sélectivité. Un des atouts de ce nouveau système est la possibilité de réaliser une procédure « tout-en-un ». La troisième partie porte sur la synthèse de nouveaux hétérocycles phosphorés. Suite à la dimérisation réductrice d'alcynes vrais avec le système Cp2ZrCl2/La, une sélectivité est observée pour la formation de phospholes substitués en position 1, 2 et 4. Ces nouveaux composés sont oxydés par du soufre pour obtenir des thiooxophospholes qui peuvent, dans certains cas, subir une dimérisation [2+2]. La dernière partie présente la mise au point d'une méthodologie de synthèse de cyclopropylamines secondaires utilisant le système Ti(OiPr)4/RMgBr. / This thesis deals with the study of the combination of group 4 metal complexes with lanthanides.The first part of this work presents the reduction of dichlorometallocenes with lanthanides. Depending on the lanthanide, different oxidation states of titanium can be accessed. With an excess of lanthanide metal, it is possible to reduce the metallacyclopentadienes formed during the reductive dimerization of alkynes carrying one aryl group.The second part concerns the modification of the Takeda carbonyl olefination system. The system Cp2TiCl2/Dy, without phosphite, allows the conversion of many carbonyl compounds into alkenes with a good selectivity in certain cases. One of the advantages of this new system is the possibility to perform an “all-in-one” procedure.The third part is about the synthesis of new phosphorous heterocycles. Following the reductive dimerization of terminal alkynes using the Cp2ZrCl2/La system, the selective transformation of the reaction intermediates into 2,4-disubstituted phospholes is observed. These new compounds can be converted into thiooxophospholes with sulfur, which in some cases undergo a [2+2] dimerisation.The last part presents a new methodology for the synthesis of secondary cyclopropylamines with the Ti(OiPr)4/RMgBr system.

Les ions métalliques sont essentiels pour le vivant. Une machinerie complexe tant au niveau cellulaire qu’au niveau de l’organisme entier permet de réguler finement leurs concentrations. Un dérèglement de leur homéostasie est souvent associé à des maladies. Afin de mieux comprendre les processus biologiques dans lesquels ces métaux sont impliqués, il est important de pouvoir les détecter, les suivre et les quantifier. Le but de ma thèse a été de synthétiser des sondes luminescentes pour la détection sélective du Zn2+ et du Cu+ au sein de cellules. Nous avons préparé et caractérisé des macromolécules sophistiquées présentant les qualités requises pour un tel objectif. Ces molécules sont synthétisées par méthode convergente mettant en jeu différentes ligations chimio sélectives.Nous avons développé une famille de sondes sélectives de Zn2+, intensiométriques ou ratiométriques et émettant dans le visible ou dans le proche infrarouge. En vue de réaliser des sondes pour l’imagerie cellulaire par microscopie confocale, nous avons mis au point une méthode de synthèse pour ajouter différentes séquence de pénétration à ces sondes. Elles ont été ensuite testées in cellulo. Bien qu’elles ne permettent pas la détection du zinc, elles ont néanmoins permis d’identifier une séquence de pénétration permettant une internalisation cellulaire. Nous avons ensuite développé une sonde incorporant deux complexes de lanthanides (terbium et europium) pour la détection du Cu+. Cette sonde répond parfaitement à la présence de Cu+ avec un signal ratiométrique. Son comportement contre intuitif a été étudié grâce à la synthèse et la caractérisation de différents « mutants ». / Metal ions are essential for life. Complex machineries at both the cellular and the whole organism levels regulate finely their concentrations. A disruption of their homeostasis can lead to disorders and serious diseases. In order to better understand the biological processes involving these metals, it is important to be able to detect, track and quantify them. The aim of my PhD was to develop luminescent probes for the detection of Zn2+ and Cu+. We prepared and characterized sophisticated molecules exhibiting the qualities required for this goal. These molecules were synthesized by convergent methods involving various chemoselective ligations. We developed a family of selective zinc probes, inensiometric or ratiometric, which emitted in the visible or near infra red. In order to elaborate probes for cellular imaging by confocal microscopy, we designed a synthetic pathway to add different penetrating peptides to these probes. They were tested in cellulo. Although they didn’t demonstrate zinc detection, they allowed identification of the penetrating sequence which permitted the cellular internalisation. We then developed a probe which incorporated two lanthanide complexes (terbium and europium) for the Cu+ detection. This probe responds perfectly to the presence of Cu+ with a ratiometric signal. Its counter-intuitive behaviour was studied thanks to the synthesis and the characterisations of different « mutants ».

L’augmentation des activités humaines dans le domaine nucléaire civil comme militaire est à l’origine d’une dissémination effective ou potentielle de radionucléides dans l’environnement. Leur mobilité dépend de plusieurs facteurs tels que le pH, la force ionique, le degré d’oxydation et la présence de ligands organiques. Afin de garantir la sûreté de sites d’entreposage ou de stockage, de développer des procédés de remédiation de sols contaminés, il est nécessaire de disposer de données fondamentales sur les interactions entre actinides et ligands organiques susceptibles d’être présents dans l’environnement, vecteurs de migration ou de piégeage de ces radioéléments. Dans ce contexte, l’étude s’est axée sur les interactions entre Th(IV), U(IV,VI), Cf(III) and Eu(III) et des dérivés hydroxamates, en particulier, la desferrioxamine B, un sidérophore bactérien comportant trois fonctions hydroxamiques. Les constantes de formation des complexes sont déterminées en fonction de l’acidité et de la concentration de ligand à force ionique et température fixées en mettant en jeu plusieurs techniques expérimentales et des concentrations en élément comprises entre 10⁻¹⁰ et 10⁻³ M (extraction liquide-liquide combinée à une détection par spectrométrie γ, électrophorèse capillaire avec détection UV, spectrophotométrie d’absorption UV-visible). L’approche thermodynamique de cette étude est complétée par une étude structurale à l’aide de techniques spectroscopiques telles que la spectroscopie infrarouge à transformée de Fourier et de la spectroscopie d’absorption des rayons X. Ces mesures expérimentales sont alors confrontées à des calculs théoriques (DFT), afin de déterminer l’arrangement structural du métal et les distances interatomiques. / Due to the increasing human activities in the civilian nuclear fields, the actual and potential release of radionuclides into the environment is a matter of concern. The mobility of radio-nuclides depends on several factors such as pH, ionic strength, oxidation state and the presence of organic ligands. In order to guarantee the safety of radioactive waste storage sites and to develop contaminated soil remediation processes, it is necessary to have fundamental data on actinides and natural organic ligands interactions. This study focuses on the interaction between Th(IV), U(IV,VI), Cf(III) and Eu(III) and hydroxamates derivatives, desferrioxamine B, a bacterial siderophore with three hydroxamic functions. The stability constants of complexes are determined as function of acidity and ligand concentration, at fixed ionic strength and temperature, using several techniques and metal concentrations ranging from 10⁻¹⁰ to 10⁻³ M (liquid-liquid extraction coupled with γ-spectrometry, capillary electrophoresis with UV detection, UV-Vis absorption spectrophotometry). The thermodynamic study is supplemented by a structural one using spectroscopic techniques such as Fourier transform infrared spectroscopy and X-ray absorption spectroscopy. Experimental measurements are compared with quantum chemistry calculations (DFT) in order to determine the coordination geometry of the metal ion and the interatomic distances.

Diimine rhenium(I) tricarbonyl complexes are known as phosphorescent emitters and electro- and photocatalysts for the reduction of CO₂ to CO. Conducting metallopolymers containing this rhenium(I) moiety should not only retain the photoluminescent and catalytic properties of the complex but also gain the conductivity, processability, and mechanical flexibility typical of [pi]-conjugated polymers. A series of tricarbonyl rhenium(I) diimine-type monomers and metallopolymers have been prepared. Appended to the ligands are thiophene and 3,4-ethylenedioxythiophene (EDOT) groups for electropolymerization of the metal complexes. UV-Vis absorption and emission spectroscopy studies of the monomers indicate that light emission originates from triplet ligand-centered (³LC) [pi] [right arrow] [pi]* and triplet metal-to-ligand charge transfer (³MLCT) excited states. Additionally, both the monomers and metallopolymers show electrocatalytic activity towards the reduction of CO₂ to CO. Furthermore, the EDOT-functionalized diimine-type ligand (EDOT₂-BPP) also serves as a good sensitizing ligand for luminescent lanthanide emission. A series of lanthanide complexes that utilize tris([beta]-diketonates) and EDOT₂-BPP ligands have been synthesized and studied using X-ray crystallography and photophysical techniques. Large quantum yields and microsecond lifetimes were found for the EuIII and SmIII complexes. Complexes of TbIII were found to have weak luminescent emission due to the less-than-optimal energy gap between the sensitizing ligands and the excited state of the TbIII ion. Oligothiophenes are models for polymeric systems because of solution processability, controlled chain length, and a well-defined structure. We have synthesized a library of alkyl and polyfluoroalkyl-substituted oligothiophenes to study how molecular structure, long-range order, spatial orientation, and varying degree of electronic coupling between molecules influences charge separation in photovoltaics. These oligoalkylthiophenes have been characterized by X-ray diffraction, photophysical methods, electrochemistry, and UV-Vis and EPR spectroscopies. Although the electronic properties of these oligoalkylthiophenes do not vary with alkyl group, aggregates of oligooctylthiophene, made through solution processing, have distinct morphologies with varying amounts of electronic disorder. The extent of electronic disorder within the aggregate is determined by comparing the suppression of the 0-0 vibronic band in the fluorescence spectra to that of the non-aggregated parent molecule. This extent of electronic disorder was correlated with the local contact potential of individual aggregates through Kelvin probe force microscopy (KPFM) measurements. / text

The ability to grow materials in the nanometric size regime with controlled shape and size provide a fundamental synthetic challenge, while allowing for evaluation of such unique nanostructures in multiple applications. In this dissertation, colloidal sodium lanthanide fluoride (NaLnF4) nanocrystals are described with an overall emphasis on i) size control, ii) surface chemistry related towards their applications as nano-bioprobes, and iii) the synthesis and fundamental aspects of epitaxial layer growth generally referred as core-shell nanocrystals. Chapter 1 provides a brief overview on the basic aspects of colloidal nanocrystals. In Chapter 2, synthesis and surface modification of colloidal sodium lanthanide fluoride nanocrystals, epitaxial growth, and their applications in optical and magnetic resonance imaging is reviewed. Chapter 3 describes a phase transfer protocol utilizing polyvinylpyrrolidone and subsequent silica coating of initially hydrophobic upconverting nanocrystals. This protocol is extended in Chapter 4 using end-group functionalized polyvinylpyrrolidone and demonstrates tunability of surface charge and functional groups on upconverting nanocrystals for targeted labeling of human prostate cancer cells. The synthesis of size-tunable NaGdF4 nanocrystals below 10 nm is described in Chapter 5. These nanocrystals are evaluated for their efficacy in magnetic resonance imaging (MRI), and a fundamental insight into the effect of surface gadolinium ions in T1 MRI contrast enhancement is presented. Chapter 6 demonstrates the synthesis of tunable, epitaxial layers on upconverting (core) nanocrystals. A novel synthetic strategy is demonstrated, by deliberate defocusing and self-focusing of differently sized nanocrystals driven by the common physical phenomenon of Ostwald ripening. Utilizing the contraction of lanthanide ions along the series, a fundamental investigation on the effect of compressive/tensile strain epitaxial layer growth is presented in Chapter 7. The fundamental rule of minimal lattice mismatch for epitaxial growth takes into account only the magnitude of mismatch and not the sign of mismatch caused by a compressive/tensile strained layer. A strong asymmetric effect between the compressive/tensile layer growth given the same magnitude of lattice mismatch is observed, demonstrating the necessity of including the sign of mismatch to generate isotropic (conformal)/ pseudomorphic (coherent) epitaxial growth. Finally, in Chapter 8 conclusions and possible future work are discussed. / Graduate / 0494