Thesis (Ph. D. in Chemistry)--Vanderbilt University, Dec. 2006. / Title from title screen. Includes bibliographical references.

Orientador: Denise Bevilaqua / Orientador: Oswaldo Garcia Júnior (in memoriam) / Banca: Elizabeth Berwerth Stucchi / Banca: Peter Hammer / Banca: Antonio Carlos Augusto da Costa / Banca: Ana Teresa Lombardi / Resumo: O processo de biossorção tem sido reconhecido como alternativa potencial na concentração de metais pesados e radioisótopos a partir de corpos d'água que recebem ação antropogênica (indústria, mineração, etc.). A biossorção é um processo que se baseia na remoção de íons metálicos em solução aquosa através de interações entre o metal e determinados sítios ativos presentes em revestimentos celulares, provenientes de biomassas como algas, bactérias e fungos. Na última década, há na literatura um crescente interesse na aplicação deste processo para concentração, recuperação e separação de metais de alto valor agregado e/ou de grande demanda tecnológica, tais como as terras-raras (TR) - essenciais para fabricação de um sem-número de produtos, a citar: laseres, supercondutores, equipamentos miniaturizados, etc. Apesar de apresentarem uma considerável disponibilidade na natureza, as TR possuem alto valor agregado devido aos dispendiosos e complexos processos de separação e purificação de misturas de TR, resultado da alta similaridade química entre os elementos do grupo. Poucos países detêm processos industriais completos de separação destes metais, dessa forma, o domínio dessa tecnologia determina uma importância considerável nos aspectos geopolíticos, estratégicos e econômicos, visto a extensão de investimentos em P&D envolvidos e as descobertas geológicas nas últimas décadas das jazidas chinesas, que abrangem 80% das reservas mundiais. Este trabalho consiste em uma avaliação preliminar da utilização do processo de biossorção na biomassa Sargassum sp. para a concentração, recuperação e separação de misturas de metais TR a partir de soluções sintéticas. As interações metal-biomassa seguem uma cinética de pseudo-segunda ordem e são descritas pelo modelo de adsorção de Langmuir... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The biosorption process has been recognized as potential alternative to concentrate heavy metal and radioisotopes from wastewaters of the anthropogenic activities (industry, mining, etc.). The biosorption is a process based on removal of metallic ions in aqueous solution from interactions among the metal and determined active sites on cellular envelope of biomasses as such algae, bacteria, and fungus. In last decade, there are in the literature a crescent interest to apply this process for the concentration, recovery, and separation of metals of high aggregated value and/or high technologic demand as the rare earth metal (RE), which are essential for the manufacturing of a great number of products; e.g. lasers, superconductors, miniaturized equipments, etc. Despite of the RE present a relevant availability, they have high aggregated value due to expansive and complicate processes of separation and purification of RE mixtures, which is resulted of the high chemical similarities of the group. Few countries have complete industrial processes of separation of these metals, so the domain of this technology determines a considerable importance in geopolitical, economic, and strategic aspects because the extension of R&D investments involved and the geological discoveries of the Chinese ore deposits in the last decades, which comprise 80 % of world reserves. This work consists on evaluation of the biosorption process by Sargassum sp. biomass for the concentration, recovery, and separation of RE metals from synthetic solutions. The metalbiomass interactions follow the pseudo-second-order kinetics and they are described by the Langmuir adsorption model. Potentiometric and spectroscopic (SEM/EDX, FTIR e XPS) analyses indicate that the biomass is bounded to the RE by oxygenated groups via ionexchange and complexation mechanisms... (Complete abstract click electronic access below) / Doutor

Submitted by RAFAEL MIGUEL SÁBIO null (rafaelmsabio@gmail.com) on 2016-11-01T21:14:55Z No. of bitstreams: 1 THESE RAFAEL MIGUEL SABIO 26_10_2016.pdf: 9769437 bytes, checksum: 37a38ed4b54498b696d4fe43ebcdfa2e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-10T13:19:03Z (GMT) No. of bitstreams: 1 sabio_rm_dr_araiq_par.pdf: 1635130 bytes, checksum: e5de0aa69e20b9d8d68afedc85cab297 (MD5) / Made available in DSpace on 2016-11-10T13:19:03Z (GMT). No. of bitstreams: 1 sabio_rm_dr_araiq_par.pdf: 1635130 bytes, checksum: e5de0aa69e20b9d8d68afedc85cab297 (MD5) Previous issue date: 2016-10-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Le design de complexes luminescents hétérobimétalliques a suscité ces dernières années un intérêt croissant en raison de leurs propriétés photophysiques uniques. Dans ces complexes de lanthanide (Nd (III) et Yb (III)) associé à des chromophores du bloc d, la forte émission des métaux de transition dans le visible est utilisée pour sensibiliser de façon efficace les niveaux f-f des lanthanides(III) qui émettent à leur tour dans le visible ou l’IR selon les terres rares. Plus spécifiquement l’attention s’est focalisée sur le développement de complexes hétérobimétalliques d-f pour l’émission dans le proche infrarouge (NIR). En effet le proche infrarouge, comparé à l’UV, pénètre plus facilement les tissus biologiques humains notamment la peau. Bien que de telles propriétés confèrent à ces complexes bimétalliques un fort potentiel pour le diagnostic médical, aucun complexe hétérobimétallique d-f greffé de façon covalente à une matrice de silice n’a été décrit. Dans ce travail de nouveaux complexes hétérobimétalliques d-f contenant des ligands silylés ont été préparés et greffés sur la silice. Les complexes monomères [Ru(bpy)2(bpmd)]Cl2 (noté Ru), [Ru(bpy)(bpy-Si)(bpmd)]Cl2 (noté RuL) et [Ln(TTA-Si)3] (noté LnL3) et les complexes hétérobimétalliques d-f Ru-LnL3 et Ln-RuL (Ln = Nd3+, Yb3+) ont été préparés. La caractérisation des complexes a été effectuée par spectroscopie Raman, RMN 1H et 13C RMN. Les spectres RMN 1D 1H et 13C NMR ainsi que 2D de corrélation HSQC confirment les structures proposées. L’étude des propriétés photophysiques met en évidence l’émission de l’élément lanthanide dans le proche infrarouge ainsi que l'efficacité du processus de transfert d'énergie Ru-Ln qui est facilité par le ligand (2,2'-bipyrimidine). Les mesures de durée de vie et de rendement quantique (ET) pour le transfert d'énergie indiquent des valeurs remarquables comprises entre 30 et 84 %. La valeur du rendement quantique (ET) du complexe d'Yb-RuL, 73,4 %, est à ce jour la plus grande valeur rapportée pour un complexe hétérobimétallique Ru (II)-Yb (III). Le greffage sur différentes matrices de silice, mésoporeuse SiO2 ou dense SiO2 d, a été réalisé. Les nanohybrides SiO2-RuL, SiO2-NdL3 et SiO2-YbL3 ont été obtenus avec des taux de greffage allant de 0,08 à 0,18 mmol de complexe par gramme de silice. SiO2-RuNd et SiO2- RuYb ont été obtenus par greffage simultané des complexes silylés monomères de ruthénium et de lanthanide, des taux de greffage de 0,10 à 0,16 mmol.g-1 ont été obtenus, respectivement. Les rendements quantiques ET de transfert d’énergie des nanohybrides SiO2-RuNd et SiO2-RuYb sont respectivement de 40 and 27,5 %. La valeur remarquable obtenue pour le nanohybride impliquant le néodyme, SiO2-RuNd, s’explique par bonne adéquation entre les niveaux d’énergie du donneur et de l’accepteur. Les nanohybrides SiO2- RuYbL3, SiO2-YbRuL, SiO2d-YbRuL et SiO2-NdRuL ont été obtenus par greffage des complexes silylés hétérobimétallic d-f élaborés dans ce travail, les taux de greffage, de 0,03 à 0,17 mmol.g-1 permettent d’envisager une fonctionnalisation chimique ultérieure de ces nanoobjets. Les propriétés de luminescence de ces nanohybrides sont similaires à celles des complexes non greffés hormis pour SiO2-YbRuL and SiO2d-YbRuL qui présentent des profils de luminescence différents comparés au complexe libre Yb—RuL. Le greffage à l'intérieur des pores de la silice pourrait éviter le processus de désactivation de la luminescent contrairement au greffage sur la matrice de silice dense. Les propriétés photophysiques associées à la morphologie et à la stabilité de la matrice de silice mésoporeuse permettent d’envisager l’utilisation de ces nouveaux nanohybrides luminescents dans le proche infrarouge comme nanosondes ou nanomarqueurs de systèmes biologiques. / The design of heterobimetallic luminescent complexes has gained growing interest in recent years due to their unique photophysical properties. More specifically, the development of heterobimetallic complexes using d-block chromophores to sensitize the near-infrared (NIR) emission of lanthanide complexes (such as Nd(III) and Yb(III)) has received significant attention taking into account their longer emission wavelengths and the interest of the NIR emission which penetrates human tissue more effectively than UV light. These properties give them potential applications in medical diagnostics or biomedical assays. Transitions to excited state levels of transition metal complexes occurring in the visible and characterized by large absorption coefficients, could efficiently sensitize f-f levels of Ln(III) ions. In this work new d-f heterobimetallic complexes containing silylated ligands were prepared supported on silica materials. [Ru(bpy)2(bpmd)]Cl2 (labeled Ru), [Ru(bpy)(bpy-Si)(bpmd)]Cl2 (labeled RuL) and [Ln(TTA-Si)3] (labeled LnL3) and d-f heterobimetallic complexes, Ru—LnL3 and Ln—RuL (Ln = Nd3+, Yb3+) were prepared. Structural characterization was carried out by Raman Scattering, 1H and 13C NMR spectroscopies. Results obtained from 1H-13C HMBC and HSQC correlation NMR spectra confirm the formation of proposed complexes. Photophysical properties studies highlight the efficiency of Ru—Ln energy transfer processes in NIR-emitting lanthanide complexes mediated by conjugated bridging ligand (2,2'-bipyrimidine). Lifetime measurements were carried out and values of quantum yield for energy transfer (ET) between 30 and 84 % could be evaluated. ET of 73.4 % obtained for the Yb—RuL complex is the largest value reported for Ru(II)—Yb(III) heterobimetallic complexes so far. Grafting on different silica matrix was also demonstrated. SiO2-Ru, SiO2-NdL3 and SiO2-YbL3 nanohybrids were obtained with grafting efficiencies from 0.08 to 0.18 mmol g-1 of silica. SiO2-RuNd and SiO2-RuYb were performed from simultaneous grafting of ruthenium and lanthanides silylated complexes. Grafting efficiencies from 0.10 to 0.16 were obtained. ET of 40 and 27.5 % were obtained from SiO2-RuNd and SiO2-RuYb, respectively. The higher values observed for the Nd(III) nanohybrid is well explained by the matching of donor and acceptor energy levels. SiO2-RuYbL3, SiO2-YbRuL, SiO2 d-YbRuL and SiO2-NdRuL were carried out from grafting of d-f heterobimetallic silylated complexes. Grafting efficiencies from 0.03 to 0.17 were obtained. Luminescent properties from these nanohybrids were similar to the free complexes. However the SiO2-YbRuL and SiO2 d-YbRuL showed distinct luminescent profiles compared with the free Yb—RuL. The grafting inside the mesoporous channels may prevent luminescent desactivation processes comparing to the dense silica matrix. The photophysical properties associated with the morphology and stability of the mesoporous silica matrix allow suggesting these new NIR luminescent nanohybrids as nanoprobes or nanomarkers in biomedicine.

Made available in DSpace on 2015-03-03T11:52:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-31Bitstream added on 2015-03-03T12:07:27Z : No. of bitstreams: 1 000808184.pdf: 1760486 bytes, checksum: d17168b15a06e6e493f69355772eb43c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Foram sintetizados os compostos de fórmula geral LnL3nH2O, no estado sólido, onde Ln representa lantânio, lantanídeos e ítrio, L é o naproxeno e n+0 (Dy), 1 (La, Ce, Pr, Nd, Sm, Eu, Gd e Tb) e 2 (Ho, Er, Tm, Yb, Lu e Y). Os compostos foram caracterizados por termogravimetria/análise térmica diferencial (TG-DTA), calorimetria exploratória diferencial (DSC), difratometria de raios X pelo método do pó (XRD), espectroscopia de absorção na região do infravermelho (IR) e complexometria com EDTA. As curvas TG-DTA e DSC forneceram informações com relaçao ao comportamento térmico dos compostos e a decomposição dos compostos sintetizados. Os complexos de La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu e Y são termicamente estáveis até 227, 165, 221, 251, 248, 228, 249, 254, 240, 268, 260, 255, 263, 248, 255ºC, respectivamente. Os dados da espectroscopia de absorção na região do infravermelho sugerem uma coordenação bidentada entre o ligante e o íon metálico para os complexos de La, Ce, Pr, Nd, Sm, Eu, Gd, Tb e Dy, e uma coordenação bidentada e em ponte para os complexos de Ho, Er, Tm, Yb, Lu e Y. A utilização conjunta das técnicas IR, XRD e TG-DTA permitiu dividir os complexos em três grupos, de acordo com a quantidade de moléculas de águas presentes, com os complexos de cada grupo, isomórficos entre si. O DSC cíclico e o XRD com aquecimento mostrou que os complexos apresentam diversas transições cristalinas entre suas formas polimórficas / Solid-state compounds with general formula LnL3nH2O, in wich Ln represents lanthanum, lanthanides and yttrium, L is naproxen, and n + 0 (Dy), 1 (La, Ce, Pr, Nd, Sm, Eu, Gd e Tb) and 2 (Ho, Er, Tm, Yb, Lu e Y) were synthesized Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRD), infrared spectroscopy (IR) and EDTA complexometry were employed to characterize these compounds. The TG-DTA and DSC curves provided information concerning the thermal behaviour and thermal decomposition of synthesized compounds. La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y complexes are thermally stable until 227, 221, 251, 248, 249, 254, 240, 268, 260, 255, 263, 248 and 255ºC, respectively. The infrared spectroscopic data suggested a bidented coordination between the ligand and the metal ion to the La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy complexes, and a bidented and bridge coordination to the Ho, Er, Tm, Yb, Lu and Y complexes. From IR, XRD and TG-DTA techniques allowed to divide the complexes in three groups, according to the number of water molecules, with the complexes of each group, isomorphics. Cyclic DSC and heated XRD show that complexes present various crystalline transitions between polymorphics forms

No description available.

A method for determining the rare elements in bones and similar materials includes [eight] steps. / Master of Science

Exploration of novel lanthanide fluoride framework materials in inorganic-organic hybrid systems under solvothermal conditions towards development of new luminescent materials is discussed. X-ray single crystal and powder diffraction methods have been used as crystallographic characterisation techniques. Determination and study of luminescence properties for selected hybrid materials has also been carried out. The first organically templated luminescent lanthanide fluoride framework, [C₂N₂H₁₀]₀.₅ [Ln₂F₇] (Ln= Nd, Tb, Dy, Ho, Er, Yb and Lu), has been synthesised and characterised. This structure type consists of a three-dimensional yttrium fluoride framework incorporating two similar, but crystallographically distinct, yttrium sites. Photoluminescence studies of [C₂N₂H₁₀]₀.₅ [Y₂F₇]: Ln³⁺ (Ln³⁺ = Gd³⁺, Eu³⁺ and Tb³⁺) have been explored and characteristic luminescence emissions are reported. An inorganic-organic hybrid indium fluoride and its scandium fluoride analogue, [C₄H₁₄N₂][MF₅](M=In and Sc) is reported. The structure consists of infinite trans vertex sharing (InF₅)[subscript(∞)] chains, which are linked via H-bonded organic moieties. The scandium and fluorine local environments of [C₄H₁₄N₂][ScF₅] are characterised by ¹⁹F, and ⁴⁵Sc solid-state MAS NMR spectroscopies. A single scandium site has been confirmed by ⁴⁵Sc MAS NMR. ¹⁹F MAS NMR clearly differentiates between bridging and terminal fluorine. The photoluminescence properties of these complexes, [C₄H₁₄N₂][In[subscript(1-x)] Ln[subscript(x)]F₅] (Ln=Tb and/or Eu), have been explored. The optimum composition for Eu³⁺ doped samples occurs at x = 0.05 Eu³⁺ and the “asymmetry ratio” of R = I₅₉₀/I₆₁₅ ( ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁) gives a clear picture of the sensitivity for crystal field of the compound. For x = 0.08 Tb³⁺, a strong down-conversion fluorescence corresponding to ⁵D₄ → ⁷F₅ (green at 543.5 nm) occurs. In addition, a Tb³⁺/Eu³⁺ co-doped sample exhibits a combination of green (Tb³⁺) and orange (Eu³⁺) luminescence, with Tb³⁺ enhancing the emission of Eu³⁺ in this host. Exploration of novel indium, aluminium, and zirconium fluoride crystal structures with potential luminescent properties has also been undertaken. A chiolite-like phase K₅In₃F₁₄ (space group P4/mnc) has been synthesised. No phase transition occurs over the temperature range 113K< T< 293 K, as has been seen in other chiolite-like structures. An organically templated indium fluoride, [NH₄]₃[C₆H₂₁N₄]₂[In₄F₂₁] has been prepared; this features the trimeric unit [In₃F₁₅]³⁻ which appears to be the first of its type in a metal fluoride. A new hybrid fluoride, Sr[N₂C₂H₁₀]₂[Al₂F₁₂].H₂O has been synthesised. Because the ionic radius of Eu²⁺ is similar to that of Sr ²⁺ this may be a potential host for blue luminescent Eu²⁺. The new material KZrF₅.H₂O shows pentagonal-bipyramidal geometry of Zr⁴⁺ with a polar space group, Pb2₁m, which may potentially have ferroelectric properties.

Carbon-13 nuclear magnetic resonance is a very useful spectroscopic technique in studying organic compounds, especially when the proton NMR does not provide much information. In this study of multicyclic lactams, different NMR techniques were used: broadband decoupled spectra, single-frequency off-resonance decoupling (SFORD), and the attached proton test (APT). Lanthanide shift reagents and lanthanide relaxation reagents were also used. Almost all the carbon-13 resonances of mono-, bi-, and polycyclolactams were unambiguously assigned. The most powerful method in the assignments was based on the use of the lanthanide induced shifts (LIS) which confirmed the assignments qualitatively and quantitatively. The quantitative confirmation comes from the calculations of LIS and their comparison with the observed shifts. The carbon-13 chemical shielding of the studied lactams was analyzed and compared with analogous compounds. The results presented provide a consistent picture and the major influences in the trends of the ¹³C chemical shifts. However, no empirical relationships were derived for this series of compounds. The solution conformations of most of these lactams have been investigated using the shifts induced in their carbon-13 NMR by Yb(dpm)₃. These conformations were compared with structures obtained from X-ray data and MINDO/3 calculations. The structural analyses of ε-caprolactam and 3-azabicyclo[4.3.1]decan-4-one showed that these molecules have at least two conformations in solution. The LIS structural analyses were confirmed by using ¹³C T₁ relaxation times in Gd(dpm)₃ and Gd(fod)₃ relaxation reagents. The different contributions to the ¹³C NMR lanthanide induced shifts (LIS) were studied with emphasis in determining the importance of the ligand pseudocontact contribution. This was found to be important, especially in carbons in proximity to the complexation site.

This thesis describes the incorporation of lanthanide-doped nanoparticles into sol-gel matrices to improve the optical properties of lanthanide ions and these materials can potentially be used in white light devices, optical amplifiers. lasers. and biolabeling. Bright white light has been generated from sol-gel thin films (SiO2 and ZrO2) made with lanthanide-doped nanoparticles through up-conversion of a single 980 nm light source. The up-conversion mechanisms involved in the generation of light has been discussed. A new and potentially efficient up-conversion process named cross-relaxation-enhanced energy-transfer (CREET) up-conversion process has been described. Preparation of semiconductor sol-gel thin films with lanthanide-doped nanoparticles has been discussed and they show energy transfer from the semiconductor matrix to the lanthanide ions. The preparation and bioconjugation of nearly monodisperse (40 nm) silica-coated LaF3:Ln3 nanoparticles has been described.

Orientador: Sergio Antonio Marques de Lima / Banca: Ana Maria Pires / Banca: Alexandre de Oliveira Legendre / Resumo: Íons lantanídeos são utilizados como centros emissores em dispositivos emissores de luz, apresentam alta eficiência de emissão, porém baixa absortividade molar. Este problema pode ser contornado com o uso de ligantes orgânicos com alta absortividade e que transfiram energia de forma eficiente para os íons lantanídeos em complexos. A transferência de energia dos estados singlete e triplete do ligante orgânico para o íon emissor recebe o nome de efeito antena. Os complexos de irídio apresentam alta absortividade molar e um estado excitado, que é uma mistura do estado excitado do ligante com uma banda de transferência de carga metal ligante (3L-TCML) e que pode transferir energia de forma eficiente para os íons lantanídeos. Desta forma, os compostos multicentrados heteronucleares de íons lantanídeos ligados a complexos de irídio por um ligante que faça a ponte entre os centros metálicos podem produzir um efeito "super-antena" aumentando a eficiência de emissão nos íons lantanídeos. No trabalho desenvolvido foram realizadas sínteses e caracterizações de complexos mononucleares contendo íons Ir3+ e Eu3+, e também complexos bimetálicos tetranucleares ligados em ponte. A caracterização dos complexos foi realizada através das espectroscopias de absorção no infravermelho e UV-Vis e espectroscopia de fotoluminescência. Os espectros de fotoluminescência dos compostos mononucleares sintetizados mostram características semelhantes às encontradas na literatura, enquanto nos complexos heterobimetálicos, inéditos até o presente momento, a emissão é característica tanto dos complexos de Ir3+ quanto do íon Eu3+, indicando que houve a ligação em ponte entre os complexos, no entanto, a transferência de energia não é eficiente entre os estados excitados 3L-TCML e o estado emissor do lantanídeo. Isso ocorre devido à aproximação energética entre esses níveis o que favorece um processo de retro doação ... / Abstract: Lanthanides ions are widely used as emitting centers in light emitting devices. They hold high efficiency of emission, but low molar absorption. This problem can be overcome by the use of organic ligands that show highest molar absorbance and are able to transfer the energy of their excited state to the emitting states of the lanthanide ions. The energy transfer from the triplet and singlet levels of organic ligand to the lanthanide ion is called "antenna effect". Iridium complexes hold high molar absorption and an excited state that is a mix of ligand triplet-excited state and a charge-transfer metal to ligand band (3L-MLCT); this energy level can transfer energy efficiently to the lanthanide ions. Therefore, heteronuclear compounds multicentered of lanthanide ions bonded in bridge with iridium complexes by a ligand that connects the two metallic centers can produce a "super-antenna" effect, increasing the emission efficiency in the lanthanide ions. In this study, we synthesized and characterized mononuclear complexes containing Ir3+ and Eu3+ ions, and bimetallic tetranuclear complexes (Ir3+-Eu3+). These complexes were characterized by infrared absorption spectroscopy, UV-Visible absorption spectroscopy and photoluminescence spectroscopy. The photoluminescence spectra of the mononuclear compounds showed similar characteristics to those encountered in the literature, whereas the heterobimetallic complexes exhibit emission characteristic of both, Ir3+ complexes and Eu3+ complexes. This suggests that the bond in bridge between the metallic centers did happened, and the energy was transferred from the excited state 3L-MLCT to the emitting state of the lanthanide, but this was not very efficient. This may occurs probably by an approximation between the energy levels that favors a backdonation process. Geometry and UV-Vis spectra were simulated using quantum software, finding high agreement between the theory and experimental data / Mestre