As estruturas cristalinas dos complexos Ln(ClO4)3.6[PONH2(C6H5)2] onde Ln=Eu, La, Cu[NH2(CH3)2CCO2]2, NiBr2.4[AsO(C6H5)3].8H2O (verde) e NiBr2.4[AsO(C6H5)3].1,5(CH3C6H5).H2O (alaranjado) bem como do ligante PONH2(C6H5)2 foram determinadas por difração de raios-X. Os complexos envolvendo íons lantanídeos refinaram a fatores R finais de R(Eu)=0,125, e R(La)=0,133 e foram encontradas a seguintes características principais: a) o sistema cristalino é cúbico; b) a coordenação do cátion é feita por seis átomos de oxigênio dos ligantes em configuração octaédrica (Eu) e antiprismática trigonal (La) com as terras raras em posições de alta simetria (23 para Eu e 3 para La); c) o restante das estruturas apresentam diferentes graus de desordem. À luz da sua configuração geométrica, a presença de uma forte banda 5Do-7F2 no espectro de fluorescência do complexo de Eu, proibida por considerações de simetria, é explicada como decorrente de acoplamentos vibrônicos. O desdobramento da linha υP=0 do espectro de infravermelho do coplxo de La é atribuído à presença de grupos P=0 não equivalentemente ligados a terra rara devido à desordem desta. O composto envolvendo o íon Cu(II) (fator R final 0,053) cristaliza no sistema monoclínico com os complexos se empacotando em camadas paralelas ao plano cristalino (100) com redes de pontes de H intracamada e com francas interações entre camadas consecutivas, o que explica o comportamento magnético quasi-bidimensional observado nestes cristais. O complexo de Ni(II) de coloração verde (fator R final 0,039) apresenta o íon metálico sobre um centro de simetria coordenado por seis moléculas de água numa conformação octaédrica distorcida, as quais estão ligadas aos grupos tfaso[AsO(C6H5)3] e íons brometo por fatores pontes de H. No complexo de coloração alaranjada (fator R final 0,087) o cátion está pentacoordenado com os quatro oxigênios dos ligantes tfaso formando a base de uma pirâmide quadrangular e um ânion Br- ocupando a quinta posição. Como uma conseqüência da resolução e refinamento da estrutura do complexo de Eu, a estrutura cristalina do ligante PONH2(C6H5) puro foi também determinada e refinada a um fator R de 0,033. / The crystal structure of the complexes Ln(ClO4)3.6[PONH2(C6H5)2] where Ln=Eu, La, Cu[NH2(CH3)2CCO2]2, NiBr2.4[AsO(C6H5)3].8H2O (green), NiBr2.4[AsO(C6H5)3.1,5(CH3C6H5).H2O (orange) and of the ligand PONH2(C6H5)2 have been determined by X-ray diffraction. The complexes involving lanthanide ions refined to final R factors of R(Eu)=0.125 and R(La)=0.133 and the following main features were found: a) the crystal system is cubic; b) the cation is coordinated to six ligand oxygens in octahedral earths on position of high symmetry (23 for Eu and 3 for La); c) the rest of the structures shows different degrees of disorder. In the light of the geometrical configuration, the occurrence of a strong band 5Do-7F2 in the fluorescence spectrum of the Eu complex, forbidden on symmetry grounds, is interpreted as a consequence of vibronic coupling. A splitting of the infrared υP=0 band in the La complex is attributed to the presence of P=0 goups non-equivalently bonded to the rare earth due to the disorder of this atom. The compound involving the Cu(II) ion (final R factor of 0.053) crystallizes in the monoclinic system with the complexes packed in layers parallel to the (100) crystal plane, with intralayer nets of H bonds and weak interactions between consecutive layers, which explains the quasi two-dimensional magnetic behavior observed in these crystals. In the green Ni(II) complex (final R=0.039), the metallic ion is sited on a center of symmetry and is octahedrally coordinated to six water molecules which are hydrogen bonded to the tfaso[AsO(C6H5)3] groups and the bromide ions. In the orange complex (final R=0.087) the cation is pentacoordinated with the four oxygens of the tpas ligands forming the basis of a quadrangular pyramid and one Br- anion in the fifth position. As a by product in the solution and refinement of the Eu complex structure, the crystal structure of the pure ligand PONH2(C6H5) was also determined and refined to a R-factor of 0.033.

Este trabalho consiste na investigação termoanalítica dos p-toluenossulfonatos de terras raras hidratados, abordando aspectos relativos à etapa de desidratação, decomposição térmica dos sais anidros e metodologia alternativa para obtenção de oxissulfetos. As reações entre o ácido p-toluenossulfônico e hidroxicarbonato de terras raras (III), em meio aquoso, conduziram a compostos de fórmula geral mínima TR(C7H7SO3)3.xH2O, sendo TR3+ = La ao Lu e Y com x variando de 2 a 7. Esta estequiometria foi estabelecida a partir dos resultados de análise elementar e termogravimetria. Os compostos foram caracterizados e, posteriormente, investigados termoanaliticamente. O estudo do comportamento térmico dos compostos foi realizado empregando a TG/DTG em atmosfera dinâmica de ar, N2, CO2, ar + CO2 e H2 + Ar a uma razão de aquecimento de 10°C min-1. A etapa de desidratação mostrou-se independente da atmosfera empregada. O processo de decomposição térmica do sal anidro em ar, CO2, ar + CO2 conduziu a formação de oxissulfatos com diferentes estequiometrias. Os resultados indicaram que a estabilidade térmica dos p-toluenossulfonatos anidros e dos oxissulfatos diminui com o raio do íon TR3+. O mesmo não ficou evidenciado quando se utilizou atmosfera de N2, uma vez que nenhum patamar indicativo de produtos intermediários e/ou finais termoestáveis foi formado. Os dados TG em atmosfera de H2 + Ar indicaram a formação de dioxissulfeto (TR2O2S). Isto foi confirmado pelo reaquecimento do produto em atmosfera de ar, que evidenciou ganho de massa característico da oxidação a oxissulfato. Os eventos térmicos foram evidenciados nas curvas DSC, por picos no sentido endotérmicos ou exotérmicos, e estão em concordância com as variações de massa indicadas nas curvas TG/DTG. Para alguns compostos foram determinados os parâmetros cinéticos, para etapa de desidratação, utilizando método dinâmico por TG/DTG e DSC. As curvas TG mostraram alguns eventos sobrepostos, evidenciando um processo de decomposição térmica aparentemente complexo, característico da saída de vários produtos voláteis simultaneamente. Neste caso, os experimentos utilizando o sistema simultâneo e acoplado TG/DTA-GC/MS possibilitou a detecção e análise destes voláteis. / This work consists in the thermoanalytical investigation of hydrated rare earth p-toluenesulfonates, considering the relative aspects of the dehydration step, thermal decomposition of the anhydrous salts and altemative methods for preparation of the oxysulfides. The compounds were prepared in aqueous solution, by reaction of p-toluenesulfonic acid and basic carbonates. The products of the reactions presented general formula TR(C7H7SO3)3.xH2O, TR3+ = La - Lu and Y, and x = 2 - 7. This stoichiometry was established through elemental analysis and TG data. The p-toluenesulfonates were characterized and investigated thermoanalytically. The study of the thermal behaviour of these compounds was accomplished using TG/DTG in air, N2, CO2, air + CO2 and H2 + Ar dynamic atmospheres with heating rate of 10 °C min-1. The dehydration step is independent of the atmosphere employed. The thermal decomposition processes of the anhydrous salts in air, CO2, air + CO2 lead to fonnation of oxysulfates with different stoichiometries. The results indicated that thermal stability of anhydrous salts and oxysulfates decreases with ionic TR3+ radii. The same was not evidenced in the N2 atmosphere plateaus indicative of thermally stables intermediate compounds were not observed. TG data in H2 + Ar atmosphere indicated the formation of dioxysulfide (TR2O2S). This product was heated in air atmosphere, showing gain of mass characteristic of oxidation to oxysulfate. The thermal events were evidenced in DSC curves by endothermic and exothermic peaks, and they are in agreement with the weight changes indicated in TG/DTG curves. For some compounds kinectic parameters were determined for the dehydration step, using TG/DTG and DSC dynamic methods. TG curves showed some overlaped events, evidencing complexes thermal decomposition processes with simultaneously evoluation of several volatile products. In these case, TG/DTG-GC/MS experiments were made for the detection of these volatile ones.

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No. of bitstreams: 1 victorhugofelipebernardes.pdf: 4330159 bytes, checksum: 8ed0f32ccd734b911991c27470472e98 (MD5) Previous issue date: 2012-08-03 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Este trabalho descreve a síntese e caracterização de oito complexos envolvendo os ligantes N,O doadores, piridino-3,5-dicarboxilato (3,5-pdc); piridino2,5-dicarboxilato (2,5-pdc); piridino-2,6-dicarboxilato (2,6-pdc) e isonicotinato (iso). Todos os compostos foram caracterizados por espectroscopia de absorção atômica de chama, espectroscopia vibracional na região do infravermelho e Raman, análise elementar de CHN e análise térmica (TG/DTA). As caracterizações indicam que seis desses complexos são heterobimetálicos do tipo 3d-4f, ou seja, apresentam em sua fórmula molecular um metal do bloco d [Co(II) ou Cu(II)] e um metal do bloco f [Eu(III) ou Sm(III)]. As caracterizações sugerem ainda que os complexos EuCo(3,5pdc) e EuCu(3,5-pdc) sejam isoestruturais, assim como os compostos SmCu(2,5pdc), EuCo(2,5-pdc) e EuCu(2,5-pdc). Outros dois complexos intitulados Co(3,5-pdc) e Eu(iso) tiveram suas estruturas determinadas através da difração de raios X por monocristal. A estrutura do complexo Co(3,5-pdc) pertence ao sistema cristalino monoclínico, grupo espacial P21/n, apresentando a fórmula molecular [Co(3,5pdc)(H2O)5]dmso. O sítio de Co(II) apresenta geometria octaédrica distorcida, sendo a esfera de coordenação composta por cinco ligantes aqua e um átomo de nitrogênio do ligante 3,5-pdc. Nesse caso, os grupos carboxilatos do 3,5-pdc não estão envolvidos na coordenação. O composto Eu(iso) com fórmula mínima [Eu(iso)3(H2O)2]n cristalizou-se no sistema monoclínico, pertencendo ao grupo espacial P21/c e mostrou-se como um polímero de coordenação 1D. O íon Eu(III) está coordenado a oito átomos de oxigênio apresentando geometria antiprismática quadrada distorcida. Os ligantes iso adotam dois modos de coordenação: bidentado quelato e em ponte. Os compostos heterobimetálicos juntamente com o complexo Eu(iso), foram estudados por espectroscopia de luminescência. Os espectros de luminescência indicam que a excitação direta no comprimento de onda da transição π→π* do ligante é mais eficiente que a excitação direta no metal, caracterizando a sensibilização do lantanídeo. O diagrama de cromaticidade CIE revela que as emissões apresentam alta pureza, com coordenadas X e Y próximas da borda. / This work describes the synthesis and characterization of eight complexes involving the N,O-donor ligands, pyridine-3,5-dicarboxylate (3,5-pdc); pyridine-2,5dicarboxylate (2,5-pdc); pyridine-2,6-dicarboxylate (2,6-pdc) and isonicotinate (iso). All compounds were characterized by atomic absorption spectroscopy, infrared and Raman vibrational spectroscopies, CHN elemental analysis and thermal analysis (TG/DTA). The characterization techniques indicate that six of these are 3d-4f heterobimetallic complexes, in other words, present in their molecular formulae a dblock metal [Co (II) or Cu (II)] and a f-block metal [Eu (III) or Sm (III)]. The characterization techniques also suggest that complexes EuCo(3,5-pdc) and EuCu(3,5-pdc) are isostructural, as well as compounds SmCu(2,5-pdc), EuCo(2,5pdc) and EuCu(2,5-pdc). Two other complexes entitled Co(3,5-pdc) and Eu(iso) had their structures determined by single-crystal X-ray diffraction analysis. Complex Co(3,5-pdc) structure belongs to the monoclinic crystal system, space group P21/n, with molecular formula [Co(3,5-pdc)(H2O)5]dmso. Co(II) sites adopt a distorted octahedral geometry, with the coordination sphere composed of five aqua ligands and one nitrogen atom from 3,5-pdc ligand. In this case, the 3,5-pdc carboxylate groups are not involved in coordination. Eu(iso) compound, with molecular formula [Eu(iso)3(H2O)2]n crystallized in the monoclinic system, belonging to space group P21/c and appeared as a 1D coordination polymer. The Eu(III) ion is coordinated to eight oxygen atoms displaying distorted square antiprismatic geometry. The iso ligands adopt two coordination modes: bidentate chelate and bridging. The heterobimetallic compounds along with the complex Eu(iso), were studied by luminescence spectroscopy. The luminescence spectra indicate that the direct excitation wavelength of the π → π* transition of the ligands is more efficient than direct excitation into the metal, characterizing lanthanide sensitization. The CIE chromaticity diagram shows that the emissions have high purity, with X and Y coordinates near the edge.

Ce travail est consacré à la synthèse et la caractérisation des commutateurs et des fils moléculaires incorporant l'unité et le ruthénium organométalliques fractions photochromiques. La première partie traite de lanthanides complexe Yb combiné avec l'unité et le ruthénium acétylure fractions photochromiques afin de moduler la luminescence avec l'aide de redox et de stimuli lumineux. Dans la deuxième partie explique la combinaison d'unités DTE photochromiques avec des fragments acétylures de ruthénium pour fixer sur la surface de nanoparticules métalliques afin d'affiner leur résonance plasmonique grâce à la modification de l'environnement de surface en utilisant la lumière et redox stimuli. La troisième partie décrit la préparation de complexes de lanthanides combinés avec une unité photochromique spiropyranne pour commuter les propriétés SMM des complexes via photoisomérisation de l'unité spiropyranne. Dans la dernière partie, nous présentons la synthèse de Oligo (phénylène éthylène) Les fils moléculaires avec différents noyaux centraux afin d'obtenir une variété de fil avec différents niveaux d'énergie HOMO-LUMO pour vérifier l'effet de l'épinglage. / This work is devoted to the synthesis and characterization of novel molecular switches and wires incorporating photochromic unit and ruthenium organometallic moieties. The first part deals with lanthanide Yb complex combined with photochromic unit and ruthenium acetylide moieties in order to modulate the luminescence with the help of redox and light stimuli. In the second part explained the combination of photochromic DTE units with ruthenium acetylide moieties to attach on the surface of metal nanoparticles in order to tune their plasmonic resonance through the surface environment modification by using light and redox stimuli. The third part describes the preparation of lanthanide complexes combined with a spiropyran photochromic unit in order to switch the SMM properties of the complexes via photoisomerization of the spiropyran unit. In the last part, we report the synthesis of Oligo(phenylene ethylene) molecular wires with different central cores in order to obtain various wire with different HOMO-LUMO energy levels to check the effect of pinning.

Dans le but d’élucider la chimie de coordination et la structure des complexes formés avec des ligands organiques de la famille des sidérochélates, des études physico-chimiques sur la complexation du fer(III), de certains lanthanides(III) (La3+, Nd3+, Sm3+, Eu3+, Gd3+, Ho3+, Lu3+) et de l’uranium(VI) ont été effectuées. La connaissance des propriétés de complexation sidérophore-actinide est une étape essentielle pour appréhender le comportement à long terme d'un sol contaminé par des radioéléments. Trois acides dihydroxamiques synthétisés au laboratoire ((LCyEt)2–, (LCyPr)2– et (LO)2–) mimant un sidérophore d’origine fongique, l’acide rhodotorulique, ont été évalués pour la chélation du fer(III) par des titrages potentiométriques éventuellement couplés à une détection spectrophotométrique en milieu KNO3 0,1 M. Ces mesures ont permis de confirmer la présence de complexes di- et trileptiques dans les conditions d’excès du ligand. Le modèle chimique comprend au total cinq espèces de formule [Fem(L)lHh](3–2l+h)+ : [Fe(L)]+, [Fe(L)(OH)], [Fe(L)(OH)2]–, [Fe(L)2H] et [Fe2(L)3]. Le traitement numérique des données spectrophotométriques collectées dans le visible nous a conduit à proposer le spectre électronique pour chacune des espèces identifiées. En outre, la spectroscopie de masse par ionisation électrospray (ESI-MS) a confirmé la formation des espèces mono- ([Fe(L)]+) et dileptiques ([Fe(L)2H]). L’étude potentiométrique du ligand dihydroxamique abiotique (LCyPr)2– en présence de sept lanthanides trivalents a permis de proposer un modèle chimique comprenant cinq espèces mono- et dileptiques ([Ln(LCyPr)]+, [Ln(LCyPr)H]2+, [Ln(LCyPr)2]−, [Ln(LCyPr)2H]) et une espèce monohydroxylée [Ln(LCyPr)OH] en milieu KNO3 0,1 M. Par ailleurs, les mesures potentiométriques et spectrophotométriques pour le système UO22+/(LCyPr)2– suggèrent la formation à l’équilibre de cinq complexes d’uranium(VI) entre p[H] 2 et 10. Le modèle comprend les complexes mono- et dileptiques suivants : [UO2(LCyPr)], [UO2(LCyPr)H]+, [UO2(LCyPr)OH]−, [UO2(LCyPr)2]2− et [UO2(LCyPr)2H]−. La combinaison de ces deux techniques nous a permis d’appréhender la spéciation de ce radionucléide en milieu KNO3 0,1 M et de proposer des schémas de coordination pour les différentes espèces mises en évidence / With the aim of elucidating the coordination chemistry and the structure of the complexes formed with organic ligands belonging to the family of siderochelates, physico-chemical studies of the complexation of iron(III), some lanthanides(III) (La3+, Nd3+, Sm3+, Eu3+, Gd3+, Ho3+, Lu3+) and uranium(VI) have been performed. The knowledge of the properties of actinide-siderophore complexes is an essential step to assess long-term behavior of soils contaminated by actinides. Three dihydroxamic acids synthesized in our laboratory ((LCyEt)2–, (LCyPr)2– and (LO)2–) mimicking a fungal siderophore, rhodotorulic acid, have been evaluated with respect to iron(III) chelation by potentiometric and spectrophotometric titrations in 0,1 M KNO3. These measurements revealed the formation of di- and trileptic complexes in the presence of an excess of ligand. The chemical model includes five species of [Fem(L)lHh](3–2l+h)+ general formula : [Fe(L)]+, [Fe(L)(OH)], [Fe(L)(OH)2]–, [Fe(L)2H] and [Fe2(L)3]. The numerical treatment of the spectrophotometric data collected in the visible range, led us to propose the electronic absorption spectrum for each of the identified species. Moreover, electrospray ionization mass spectroscopy (ESI-MS) confirmed the formation of the mono- ([FeL]+) and dileptic ([FeL2H]) complexes. The potentiometric study of the abiotic dihydroxamic ligand (LCyPr)2– in the presence of seven trivalent lanthanides allowed us to propose a chemical model which includs five mono- and dileptic species ([Ln(LCyPr)]+, [Ln(LCyPr)H]2+, [Ln(LCyPr)OH], [Ln(LCyPr)2]–, [Ln(LCyPr)2H]) in 0,1 M KNO3. Finally, potentiometric and spectrophotometric measurements for the UO22+/(LCyPr)2– system suggested the formation at equilibrium to five of uranium(VI) complexes between p[H] = 2 and 10. The model includes the mono- and dileptic [UO2(LCyPr)], [UO2(LCyPr)H]+, [UO2(LCyPr)OH]–, [UO2(LCyPr)2]2–, [UO2(LCyPr)2H]– complexes. The combination of both techniques allowed us to assess the speciation of this radionuclide in KNO3 medium and to propose a coordination scheme for each complex

Contrast agents for magnetic resonance imaging (MRI) are but one of a variety of nanosystems that have incredible potential for the detection and diagnosis of cancer. Nanosystems share a common disadvantage: they are quickly sequestered by biological processes that clear foreign material from the body, requiring ever larger doses to accumulate in targets, and reducing their overall effectiveness and viability. This thesis explores a pair of strategies for nanomaterials to boost their evasiveness from these defensive systems in the context of lanthanide MRI contrast agents, in an attempt to increase their probability to collect in cancerous tissue. Chapter 1 provides precedent and rationale for the modification of two parameters regarding novel nanosystem design: aspect ratio and zeta potential. Chapter 2 details the controlled syntheses and analysis of sodium dysprosium fluoride nanomaterials at a range of aspect ratios. Chapter 3 concerns the construction of tunable zwitterionic polymer coatings for synthesized nanomaterials to demonstrate control over the zeta potential in aqueous dispersion. Chapter 4 tests polymer-coated spherical nanoparticles and nanorods for internalization into or adsorbance onto a cancerous cell line. Chapter 5 summarizes the work of the previous chapters and suggests future research approaches. Though internalization or adsorbance onto HeLa cells was not observed for prepared nanomaterials, control over their aspect ratio at the synthetic level and zeta potential via constructed zwitterionic polymers was demonstrated, with implications for application to a plethora of nanosystems. / Graduate

ABSTRACT This work is focused on the synthesis of a family of new macrocyclic ligands with exchangeable protons on coordinating groups that could potentially serve (after complexation with suitable paramagnetic lanthanide(III) ions) as responsive contrast agents (CAs) for magnetic resonance imaging (MRI). It is expected that measurement of extracellular pH should bring information for tumorous disease diagnoses and/or for suggesting the most efficient treatment. Therefore, our attention was focused on pH-dependent CAs based on a PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) mechanism capable of reporting pH changes in tissue. The PARACEST-related properties of a series of Ln(III) complexes with the CEST effect caused by amino groups coordinated to the central Ln(III) metal ions were investigated. Such a kind of PARACEST CA is new and has had no precedent in the literature. It was shown that these Ln(III) complexes produce a pH-sensitive PARACEST effect in the pH region relevant for living systems. The study brings proof-of-principle for utilization of complexes with a linear diamine pendant arm, i.e. complexes with two exchanging proton pools, for ratiometric pH determination by MRI independently on the probe concentration. In addition, to ensure a higher kinetic inertness of the...

Comme la demande mondiale des éléments de terres rares (ETR) ne cesse d'augmenter, de nouveaux projets d'exploration ont été lancés dans de nombreux pays, incluant au Canada. Le présent projet découle d'un programme communautaire environnemental issu d'une collaboration entre des chercheurs et la communauté inuite de Kangiqsualujjuaq suite à la proposition d’un projet minier d'ETR au Nunavik. Pour répondre aux études limitées sur la distribution des ETR dans les environnements non pertubés, cette étude rapporte les niveaux actuellement observés des sédiments, des lichens et de multiples espèces animales provenant d'écosystèmes terrestres, d’eau douce et du milieu marin du subarctique de l’est du Canada. Les résultats suggèrent que toutes les matrices ont la capacité d'accumuler les ETR, bien qu'une dilution trophique soit notée. De plus, l’analyse des tissus d’espèces alimentaires traditionnelles a démontré que le foie des vertébrés avait des concentrations d'ETR plus élevées que le muscle et le gras, tandis que les tissus osseux et rénaux présentaient généralement des concentrations intermédiaires. En outre, les tendances observées pendant l'analyse des anomalies du cérium sensibles aux transformations d’oxydoréduction ont suggéré que ces anomalies peuvent servir de biomarqueur dans l’exposition aux ETR et leur transformation biologique. Dans l'ensemble, cette étude présente une bioaccumulation et un fractionnement d’ETR spécifiques aux espèces et aux tissus, ce qui justifie des recherches plus approfondies afin de comprendre les facteurs de contrôle du comportement d’ETR au sein des espèces animales. Ces résultats peuvent également servir à établir des lignes directrices nationales d’ETR, et servir de référence dans les futures études de biosurveillance. / A gradual increase in the release of rare earth elements (REE) to the environment has been reported, as well as a continuous rise in their global demand. New REE exploration projects have been initiated in multiple countries, including within Canada where REE deposits are frequently located in northern regions. This project stems from a community-based environmental program between researchers and the Inuit community of Kangiqsualujjuaq in the context of a prospective REE mine in Nunavik. To address the limited review of REE distribution in natural environments, the present study reports the current REE values for sediments, lichens, and multiple animal species from terrestrial, freshwater and marine ecosystems of the eastern Canadian subarctic. Results suggest that all matrices have the capacity to accumulate REE, though a biodilution across taxonomic groups is noted. Also, a study of animal tissue samples from country food species demonstrated that liver tissues have significantly higher concentrations of REE than the muscle and blubber, with bone and kidney tissues typically presenting intermediate concentrations. Further, the analysis of redox-sensitive cerium anomalies supported the presence of tissue-specific mechanisms that suggest these anomalies may serve as a biomarker in REE exposure and biological transformation. Overall, this study presents a species- and tissue- specific bioaccumulation and fractionation of REE that warrants further investigation to better understand the controlling factors of REE processing within animal species. The results may additionally serve in the establishment of national REE guidelines for environmental health and human consumption, and act as a reference in future biomonitoring studies.

La modélisation toxicocinétique est un outil efficace pour évaluer le devenir de contaminants dans l’organisme animal ou humain. Elle peut, entre autres, servir à reconstituer une exposition à ces contaminants dans le cadre d’études de biosurveillance de l’exposition populationnelle. Ce mémoire porte sur le développement d’un modèle toxicocinétique qui permet de relier des doses d’exposition aux métaux rares, aux concentrations dans le sang et les tissus ainsi qu’aux quantités excrétées de l’organisme. Ce modèle a été développé pour des terres-rares abondantes dans l’environnement et jusqu’ici peu étudiées: l’yttrium (Y), le cérium (Ce), le praséodyme (Pr) et le néodyme (Nd). Il est utile pour reconstruire des doses absorbées à partir de données dans des matrices biologiques accessibles comme l’urine et le sang et aider à mieux interpréter des données de biosurveillance de l’exposition à des contaminants. De nouvelles données expérimentales obtenues à partir d’études expérimentales chez le rat combinées à des données de la littérature ont servi à développer le modèle. Celui-ci comprend 20 compartiments représentant différents organes, la circulation sanguine, l’urine et les fèces. Les paramètres du modèle incluent des coefficients de transfert entre les compartiments, qui décrivent la vitesse de transfert d’un compartiment à l’autre et donc la cinétique de ces métaux. Un système d’équations différentielles a été utilisé pour décrire les échanges entre les compartiments. Une fois les paramètres déterminés à partir de la littérature et par ajustement aux données expérimentales acquises, le modèle a donné une bonne adéquation aux données expérimentales disponibles sur les profils temporels des quatre métaux dans le sang, l’urine et les fèces, ainsi que sur les niveaux présents dans les organes au sacrifice. Ce modèle a ensuite servi à dériver un niveau biologique correspondant à une dose critique établie à partir d’études de toxicité chez le rat, soit la dose maximale sans effet nocif observé (NOAEL) chez le rat utilisée par la U.S. Environmental Protection Agency (U.S. EPA) pour établir des doses de référence par ingestion provisoires (p-RfD) chez l’humain à ne pas dépasser pour prévenir des effets sur la santé. Le modèle a ainsi été utilisé pour dériver les niveaux urinaires de métaux rares dans des collectes de 24 h et les concentrations urinaires correspondantes suite à la simulation d’une exposition quotidienne répétée par voie orale à cette dose critique (NOAEL) chez l'animal jusqu'à ce que l'état d'équilibre soit atteint. Afin d’obtenir une valeur biologique limite chez l’humain définie comme « équivalent biologique ou BE (de l’anglais : Biomonitoring Equivalent) », le facteur d’incertitude de 1000 utilisé par la U.S. EPA pour extrapoler le NOAEL animal à une dose de référence RfD chez l’humain a été utilisé pour les éléments disponibles. Les niveaux urinaires pouvant servir d’équivalents biologiques (BE) ont ainsi été établis à 0.03 et 0.07 µg/L pour le Pr et Nd uniquement. Les niveaux biologiques de métaux rares dans des populations exposées (niveaux urinaires ici) peuvent donc être directement comparés avec ces BE pour vérifier si des mesures devraient être prises pour réduire l’exposition. L’approche de modélisation peut être appliquée à d’autres terres rares dans une approche plus complète d’évaluation des risques associés à l’exposition à ces contaminants émergents. Il est aussi possible de recalculer les BE pour de nouvelles doses critiques. / Toxicokinetic modeling is an effective tool for evaluating the fate of contaminants in the animal or human body. It can, among other things, be used to reconstruct exposure to these contaminants in biomonitoring studies of population exposure. This thesis focuses on the development of a toxicokinetic model allowing to link exposure doses of rare earth elements (REEs) to concentration in blood and tissues as well as to amounts excreted from the body. This model was developed for abundant REEs in the environment and so far poorly studied: yttrium (Y), cerium (Ce), praseodymium (Pr) and neodymium (Nd). It is useful to reconstruct doses absorbed from data in accessible biological matrices such as urine and blood and to help better interpret biomonitoring data for exposure assessment to contaminants. New data obtained from experimental studies in rats combined with data from the literature were used to develop the model. It consists of 20 compartments representing different organs, blood circulation, urine and faeces. The model parameters include transfer coefficients between compartments, which describe the rate of transfer from one compartment to another and therefore the kinetics of these metals. A differential equation system was used to describe the exchanges between the compartments. Once the parameters were determined from the literature and by adjustment to the experimental data acquired, the model gave a good match to the data available on the temporal profiles of the four metals in blood, urine and faeces, as well as levels present in the organs at sacrifice. This model was then used to establish a biological level corresponding to a critical dose established from toxicity studies in rats, i.e. the maximum “no observed adverse effect level” (NOAEL) dose in rats used by the U.S. Environmental Protection Agency to establish provisional ingestion reference doses (RfD) in humans not to be exceeded to prevent health effects. The model was thus used to derive the urine levels of REEs in 24-h urine collections and the corresponding urine concentrations following the simulation of repeated daily oral exposure to this critical dose (NOAEL) in animals up until a state of equilibrium was reached. In order to obtain a biological limit value in humans defined as "biological equivalent or BE", the uncertainty factor of 1000 used by the U.S. EPA to extrapolate the animal NOAEL to a RfD reference dose in humans was used. Urinary levels that can serve as biological equivalents (BE) were thus established at 0.03 and 0.07 µg/L for Pr and Nd. Biological levels of REEs in exposed populations (urinary levels here) can therefore be directly compared with these BEs to verify whether measures should be taken to reduce exposure. The modeling approach can be applied to other REEs in a more detailed risk assessment approach associated with exposure to these emerging contaminants. It is also easily possible to recalculate the BEs for new critical doses.

Many Zintl phases exhibiting a CrB type structure form hydrides. Systematic studies of AeTtHx (Ae = Ca, Sr, Ba; Tt = Si, Ge, Sn), LnTtHx (Ln = La, Nd; Tt = Si, Ge, Sn), and LnGaHx (Ln = Nd, Gd) showed the vast structural diversity of these systems. Hydrogenation reactions on REGa (RE = Y, La, Tm) and RESi (RE = Y, Er, Tm) were performed in steel autoclaves under hydrogen pressure up to 5 MPa and temperatures up to 773 K. The products were analyzed by X-ray and neutron powder diffraction. RESi (RE = Y, Er, Tm) form hydrides in the C-LaGeD type. LaGaD1.66 is isostructural to NdGaD1.66 and shows similar electronic features. Ga-D distances (1.987(13) Å and 2.396(9) Å) are considerably longer than in polyanionic hydrides and not indicative of covalent bonding. In TmGaD0.93(2) with a distorted CrB type structure deuterium atoms exclusively occupy tetrahedral voids. Theoretical calculations on density functional theory (DFT) level confirm experimental results and suggest metallic properties for the hydrides.