Ce travail de thèse visait à développer une nouvelle famille de ligands de type bispidines pour la complexation du cuivre(II) en vue d’applications en tomographie par émission de positrons(TEP). En effet, le cuivre 64 est un radioélément dont l’étude dans le cadre de l’imagerie TEP est en plein essor. Les bispidines, quant à elles, présentent l’intérêt de posséder une structure rigide et pré-organisée permettant la complexation de nombreux métaux de transitions.Nous présentons ici la synthèse et l’optimisation de nouveaux ligands dont les propriétés structurales et physico-chimiques ont été étudiées. Un ligand a montré de très bons résultats puisqu’il possède tous les paramètres cinétiques et thermodynamiques nécessaires à un chélatant utilisé en imagerie TEP. Différentes voies de fonctionnalisation ont ensuite été étudiées afin d’obtenir divers chélatants bifonctionnels. Un ligand comportant une lysine a pu être couplé à une fonction maléimide (régiosélective des cystéines), à une biotine (possédant une forte interaction pour la streptavidine) ou encore à un motif Bodipy pour l’obtention d’une sonde bimodale (UV-visible et TEP). Enfin, nous présentons l’extension de cette famille de bispidines par l’augmentation du nombre de fonctions de coordination présentes ou encore par l’obtention de ligands tricycliques en vue de moduler la sélectivité de ces molécules. / This work aimed to develop a new family of bispidine-type ligands for copper(II) complexation with applications in Positron Emission Tomography (PET). Indeed, copper 64 is a radioelement whose study in PET imaging is booming. Bispidines have the benefit of having a rigid and preorganized structure for complexation of a large number of transition metals. In this work we present the synthesis and optimization of new ligands whose structural and physico-chemical properties have been studied. One ligand showed very good results because it possesses all of kinetic and thermodynamic parameters which are necessary for its application to PET imaging. Different strategies of functionalization have been studied to obtain bifunctional chelates. A lysine derivative has been coupled to a maleimide function (regioselective of cysteins), to abiotine (which displays a strong affinity for streptavidin) or to a Bodipy pattern for obtaining a bimodal probe (UV-visible and PET). Finally, we present an extension of this bispidine family by increasing the number of coordination functions or by synthesizing tricyclic compounds to modulate the selectivity of these molecules.

Ce travail de thèse avait pour objectif de développer de nouveaux chélatants du cuivre(II) de type bispidine pour des applications en Tomographie à Emission de Positrons. Le 64Cu est un radioisotope métallique dont les propriétés sont intéressantes pour la TEP. Les bispidines sont des chélatants dont la structure est préorganisée et rigide. Cette propriété confère au bispidine de bonnes propriétés de coordination vis-à-vis des métaux de transition, en particulier le cuivre(II). Ce travail présente le développement d’un ligand de type bispidine possédant un groupement phosphonate ainsi que le développement de bispidines permettant la synthèse de nouvelles familles de chélatants pour le cuivre(II). La bispidine phosphonatée a ensuite fait l’objet d’une étude physico-chimique par différentes techniques, révélant ainsi qu’elle possède les caractéristiques requises pour des applications en TEP. Le radiomarquage en présence de 64Cu a été étudié pour une sélection de plusieurs chélatants et montre le fort potentiel des ligands de type bispidine pour la complexation du 64Cu. Enfin, diverses stratégies de fonctionnalisation ont été étudiées pour l’obtention d’un chélatant bifonctionnel basé sur la bispidine phosphonatée. Ces stratégies démontrent la possibilité d’obtenir deux ligands bifonctionnels. De surcroît, deux plateformes bifonctionnelles peuvent faire l’objet de point de départ pour le développement de nouvelles familles de bispidines bifonctionnelles. / This PhD work aimed at developing new bispidine-based copper(II) chelating agents for applications in Positron Emission Tomography (PET). On one hand, 64Cu is a metallic radioisotope which possesses interesting properties for PET imaging and on the other hand, bispidines have a pre-organized and rigid structure. This property makes them good chelating agents for numerous transition metals, particularly copper(II). This work presents the development of a new bispidine-based ligand having a phosphonate pendant arm as well as the development of bispidines allowing the synthesis of new chelating agents for copper(II). The physico-chemical properties of the phosphonated bispidine were thoroughly studied by different techniques, showing that it would be adequat for PET applications. Radiolabeling experiments were also done in the presence of 64Cu for various bispidines and show the high potential of bispidine ligands for the complexation of 64Cu. Finally, several functionalization strategies were studied in order to get bifunctional chelates based on the phosphonated bispidines. This study proved the possibility to develop two bifunctional bispidines based on the phosphonated one and also it allowed us to develop two bifunctional bispidines as synthon for the synthesis of new families of bifunctional bispidines.

Lavender is an important medicinal plant that is sensitive to various environmental factors. Lavender essential oils have been shown to improve human health in response to many diseases. Lavender is grown all over the world, which indicates its ability to adapt to different climates. There are no reports of its commercial cultivation in Mississippi. It has been proven that there are many factors that directly affect the plant growth and concentration of essential oils in lavender. Studying these factors that affect plant growth and essential oils will be beneficial for lavender producers. The aim of this study is to increase the production of essential oil through cultural techniques and analyze the active compounds of three Lavandula species (L. intermedia, L. angustifolia, L. stoechas) using HPLC (High performance liquid chromatography) and GC-MS (Gas Chromatography, Mass spectrometer) technology. Applications of gibberellic acid, iron chelate, Mycorrhizae, humic acid, DAP, and potash fertilizer were studied to promote plant growth and production of essential oils. The essential oils were extracted using a Soxhlet distillation. The quantity and quality of the essential oils was also evaluated using HPLC and GC-MS. The linalool, linalyl acetate, and other compounds from Lavandula may be considered natural raw material source for pharmaceuticals and cosmetic products. These vital components of the essential oil of lavender leaves, flowers, and stems (linalool, linalyl, and other compounds) were affected by chelated iron treatments, gibberellin, humic acid, and mycorrhizae. The essential oil compounds of L. angustifolia and L. x intermedia cultivars make them worth cultivating.

Palladium(II) acetate and palladium(II) chloride react with amino acids in acetone/water to yield cis or trans square planar bis-chelated palladium amino acid complexes. The naturally occurring amino acids and some N-alkylated and substituted derivatives and homologs were evaluated as ligands. Thirty-eight amino acids in total were investigated as ligands. The formation of aquo complexes in water was observed and studied by 13C NMR spectroscopy and modeled by DFT calculations. Each class of amino acid ligand is catalytically active with respect to the oxidative coupling of olefins and phenylboronic acids. Some enantioselectivity is observed and the formation of products not reported in other Pd(II) oxidative couplings is seen. Both activated and non-activated alkenes were oxidatively coupled to phenylboronic acids incorporating both electron-donating and electron-withdrawing groups. The crystal structures of nineteen catalyst complexes were obtained. The extended lattice structures arise from N-H..O or O..(HOH)..O hydrogen bonding. NMR, HRMS, FTIR, single crystal XRD, and powder XRD data are evaluated. / Ph. D.

Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. / N,N-dialkyl-N-acyl(aroyl)thiourea ligands form stable chelated complexes in a cis configuration with the platinum group metals. Such chelated complexes are generally considered substitutionally “inert” in solution, however, it was found that cis-bis(N,Ndialkyl- N-acyl(aroyl)thioureato)M(II) complexes (M = Ni(II), Pd(II) or Pt(II)) readily undergo facile chelate metathesis reactions in solution at room temperature. Upon mixing two different parent complexes, a mixed-ligand product formed in solution, with an equilibrium, or steady state, between the two parent complexes and the mixed-ligand product being attained after a period of time: M(LA)2 + M(LB)2 M(LA)(LB). All three complexes remained in solution even with a ten-fold excess of one parent complex. The presence of the mixed-ligand products in solution was confirmed by liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectra and a crystal structure of the mixed-ligand complex cis-Pd(L3-S,O)(L4-S,O). Though a number of attempts were made, it was not possible to either isolate or synthesise the mixed-ligand complexes exclusively. The equilibrium distribution and the rate of the metathesis reaction were influenced by a number of factors, including the central metal ion, the substituents on the complexed ligands and the reaction medium. In addition to these, a number of other factors, some unexpected, also played a role in the rate of the reaction. Initial concentration of the parent complexes, the age of the solutions upon mixing and the presence of impurities or additives all contributed to the overall rate of reaction. The results from these rate studies highlighted the necessity for extensively purified compounds. In addition to chelate metathesis reactions, the exchange between a cis-Pd(L-S,O)2 complex and an unbound HL ligand in solution was also investigated. Again, even with an excess of unbound ligand, all three possible complexes were present in solution. It has been shown previously that these complexes undergo a photoinduced cis-trans isomerisation under intense light, and it has been proposed that the reverse trans-cis process, which occurs in the dark, may be a metathesis reaction. In light of this, the relationship between these chelate metathesis reactions and the reverse trans-cis reaction was briefly investigated. Though the metathesis reactions were a general phenomenon in the Ni(II), Pd(II) and Pt(II) complexes of the aforementioned ligands, the experiments focused mainly on the cis-Pd(L-S,O)2 complexes due to the favourable timescales of their metathesis reactions. The primary technique to observe these reactions was reversed-phase high-performance liquid chromatography (rp-HPLC). The timescales involved in the cis-Pd(L-S,O)2 metathesis reactions as well as the stability of the Pd(II) complexes under the HPLC conditions made this technique ideal.

Orientador: Renato de Mello Prado / Resumo: A pulverização foliar de silício (Si) pode diminuir os efeitos da deficiência de zinco (Zn) nas plantas, pois a adição de Si e de Zn na calda pode aumentar a eficiência da adubação foliar, porém os efeitos em plantas de sorgo ainda não são conhecidos. Assim, objetivou-se avaliar a aplicação foliar de Si na ausência de Zn e com a adição na calda em plantas de sorgo e seus efeitos na nutrição e no desenvolvimento das plantas. O delineamento foi em esquema fatorial 4 x 2, com cinco repetições, tendo quatro concentrações de Zn, na forma de Zn-EDTA: 0; 0,60; 1,20 e 1,80 g L-1 e na ausência e na presença de Si (0,50 g L-1) na calda. Avaliou-se o acúmulo de Zn e Si, eficiência de uso de Zn, extravasamento de eletrólitos celular, teores de clorofila, carotenoides, proteína e a massa seca de parte aérea e de raiz. Nas plantas deficientes em Zn, a pulverização foliar de Si ao aumentar o acúmulo deste elemento na planta diminuiu o extravasamento de eletrólitos celular, aumentou o conteúdo dos pigmentos fotossintéticos e incrementou a produção de massa seca da parte aérea e de raiz. A pulverização foliar de Zn na forma de quelato com adição de Si na calda, em relação a sua ausência, aumentou o acúmulo de Zn na planta, o teor dos pigmentos fotossintetizantes, o teor de proteína e a produção de massa seca de raiz. Conclui-se que a pulverização foliar de Si alivia a deficiência de Zn, e a adição de Si na calda com o Zn é viável agronomicamente para plantas de sorgo. / Abstract: Foliar spraying of silicon (Si) can decrease the effects of zinco (Zn) deficiency on plants. While the addition of Si and Zn in the solution may increase the efficiency of foliar fertilization with this micronutrient, however the effects on sorghum plants are not yet known. The objective of this study was to evaluate the foliar application of Si in the absence of Zn and with the addition of different concentrations of Zn in sorghum plants and their effects on plant nutrition and development. The experiment was carried out in a 4x2 factorial scheme with five replicates having four concentrations of Zn as Zn-EDTA: 0.60, 1.20 and 1.80 g L-1 and in the absence and presence of Si (0.50 g L-1) in solution. Zn and Si accumulation, Zn use efficiency, cellular electrolyte leakage, chlorophyll content, carotenoids, protein content and shoot and root dry mass were evaluated. In the plants deficient in Zn, a foliar spraying of Si increasing the accumulation of this element in the plant, decreased the cellular extravasation and increased the photosynthetic pigments and the dry mass production of shoot and root. Foliar spraying of Zn in the chelate form with addition of Si in relation to its absence increased the accumulation of Zn in the plant, the content of photosynthetic pigments, protein content and root dry mass production. It is concluded that foliar spraying of Si alleviates Zn deficiency and the addition of Si in the solution with Zn is agronomically viable for sorghum plants. / Mestre

Made available in DSpace on 2014-12-17T15:42:03Z (GMT). No. of bitstreams: 1 HugoFLS_DISSERT.pdf: 2820205 bytes, checksum: ad87619352b0e479d50e7f9093be5ec0 (MD5) Previous issue date: 2012-10-15 / This work is a study of coordination compounds by quantum theory of atoms in molecules (QTAIM), based on the topological analysis of the electron density of molecular systems, both theoretically and experimentally obtained. The coordination chemistry topics which were studied are the chelate effect, bent titanocene and chemical bond in coordination complexes. The chelate effect was investigated according to topological and thermodynamic parameters. The exchange of monodentate ligands on polydentate ligands from same transition metal increases the stability of the complex both from entropy and enthalpy contributions. In some cases, the latter had a higher contribution to the stability of the complex in comparison with entropy. This enthalpic contribution is explained according to topological analysis of the M-ligand bonds where polidentate complex had higher values of electron density of bond critical point, Laplacian of electron density of bond critical point and delocalization index (number of shared electrons between two atoms). In the second chapter, was studied bent titanocenes with bulky cyclopentadienyl derivative π-ligand. The topological study showed the presence of secondary interactions between the atoms of π-ligands or between atoms of π-ligand and -ligand. It was found that, in the case of titanocenes with small difference in point group symmetry and with bulky ligands, there was an nearly linear relationship between stability and delocalization index involving the ring carbon atoms (Cp) and the titanium. However, the titanocene stability is not only related to the interaction between Ti and C atoms of Cp ring, but secondary interactions also play important role on the stability of voluminous titanocenes. The third chapter deals with the chemical bond in coordination compounds by means of QTAIM. The quantum theory of atoms in molecules so far classifies bonds and chemical interactions in two categories: closed shell interaction (ionic bond, hydrogen bond, van der Waals interaction, etc) and shared interaction (covalent bond). Based on topological parameters such as electron density, Laplacian of electron density, delocalization index, among others, was classified the chemical bond in coordination compounds as an intermediate between closed shell and shared interactions / Esse trabalho consiste no estudo dos compostos de coordena??o pela teoria qu?ntica de ?tomos em mol?culas, do ingl?s, QTAIM, fundamentada na an?lise topol?gica da densidade eletr?nica dos sistemas moleculares obtida tanto teoricamente quanto experimentalmente. Os temas escolhidos para serem estudados s?o o efeito quelato, os metalocenos de tit?nio de estrutura pseudotetra?drica e a liga??o coordenada. No primeiro cap?tulo, foi investigado o efeito quelato de acordo com par?metros termodin?micos e topol?gicos. A troca de ligante monodentado am?nia pelo ligante bidentado 1,2-etanodiamina de mesma natureza qu?mica aumenta a estabilidade do ?on complexo, tanto pela contribui??o da entropia, quanto da entalpia, em alguns casos, esta ?ltima teve maior participa??o para a estabilidade do ?on complexo que a entropia. Em todos os ?ons complexos, a troca de ligante monodentado para bidentado levou ao aumento dos valores eletr?nicos da topologia como densidade eletr?nica, Laplaciano da densidade eletr?nica e ?ndice de deslocaliza??o (n?mero de el?trons compartilhados entre dois ?tomos). No segundo cap?tulo, foram estudados os metalocenos de tit?nio de estrutura pseudotetra?drica com ligantes-π volumosos ciclopentadienila (Cp) e seus derivados. O estudo topol?gico mostrou a presen?a de intera??es secund?rias entre os ?tomos dos ligantes-π ou dos ligantes-σ. Verificou-se que, para os metalocenos de tit?nio com pequena diferen?a de simetria pontual e ligantes volumosos, havia uma rela??o quase-linear entre a estabilidade e o ?ndice de deslocaliza??o envolvendo ?tomos de carbono do anel (Cp) e o tit?nio. Contudo, a estabilidade n?o ? relacionada apenas ?s intera??es entre o ?tomo de tit?nio e o anel ciclopentadienila, mas ?s intera??es secund?rias influenciando na estabilidade dos titanocenos com ligantes volumosos. O terceiro cap?tulo trata da liga??o qu?mica nos compostos de coordena??o por meio da QTAIM. A teoria qu?ntica de ?tomos em mol?culas, at? ent?o, classifica as liga??es e intera??es qu?micas em duas categorias: intera??o de camada fechada (liga??o i?nica, liga??o de hidrog?nio, intera??o de van der Waals, entre outras) e intera??o compartilhada (liga??o covalente). Baseado nos par?metros topol?gicos como densidade eletr?nica, Laplaciano da densidade eletr?nica, entre outros, classificou-se a liga??o coordenada como intermedi?ria entre as intera??es de camada fechada e intera??es compartilhadas

No description available.

Membrane-based separation processes have been used extensively for drinking water purification, wastewater treatment, and numerous other applications. Reactive membranes synthesized through functionalization of the membrane pores offer enhanced reactivity due to increased surface area at the polymer-solution interface and low diffusion limitations. Oxidative techniques utilizing free radicals have proven effective for both the destruction of toxic organics and non-environmental applications. Most previous work focuses on reactions in the homogeneous phase; however, the immobilization of reactants in membrane pores offers several advantages. The use of polyanions immobilized in a membrane or chelates in solution prevents ferric hydroxide precipitation at near-neutral pH, a common limitation of iron(Fe(II/III))-catalyzed hydrogen peroxide (H2O2) decomposition. The objectives of this research are to develop a membrane-based platform for the generation of free radicals, degrade toxic organic compounds using this and similar solution-based reactions, degrade toxic organic compounds in droplet form, quantify hydroxyl radical production in these reactions, and develop kinetic models for both processes. In this study, a functionalized membrane containing poly(acrylic acid) (PAA) was used to immobilize iron ions and conduct free radical reactions by permeating H2O2 through the membrane. The membrane’s responsive behavior to pH and divalent cations was investigated and modeled. The conversion of Fe(II) to Fe(III) in the membrane and its effect on the decomposition of hydrogen peroxide were monitored and used to develop kinetic models for predicting H2O2 decomposition in these systems. The rate of hydroxyl radical production, and hence contaminant degradation can be varied by changing the residence time, H2O2 concentration, and/or iron loading. Using these membrane-immobilized systems, successful removal of toxic organic compounds, such as pentachlorophenol (PCP), from water was demonstrated. Another toxic organic compound of interest for water treatment applications is trichloroethylene (TCE). Due to its limited solubility in water, a majority of the TCE is often present in the form of droplets. In this study, effective TCE droplet degradation using chelate-modified, iron-catalyzed free radical reactions at near-neutral pH was demonstrated. In order to predict the degradation of aqueous and non-aqueous phase TCE for these reactions, a mathematical model was constructed through the use of droplet mass transfer correlations and free radical reaction kinetics.

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.