Synthesis and detailed characterization of dendrimers that evolve symmetrically from a linear bifunctional core (2-butyne-1,4-diol) with 3,5-dihydroxybenzyl alcohol based dendron wedges, are reported. The divergent, layer-by-layer build-up of the dumbbell shaped dendrimers, is based on simple acid-base hydrolytic chemistry of bis(dimethylamino)dimethylsilane with OH terminated molecules. Evaluation of some of the structure-property relationships in these dendrimers was carried out to obtain a better understanding of their potential applications. The self-assembly of these dendrimers in THF and water is significantly influenced by their generation number, the backbone structure and the solvent. Generations 1-3 dendrimers form aggregates at a higher critical aggregation concentration (cac) compared to generation 4 in THF. This behavior is related to the open structure in the lower generations with a linear core becoming important in their self-assembly, while in generation 4, more globular architecture with more prominent hydrogen bonding sites, facilitates self-assembly at lower concentrations. In water and in generations 1 and 2 dendrimers, the inability of more polar solvent to interact with their backbones, leads to aggregates that are formed by minimizing the repulsive forces. In generations 3 and 4, the major interaction of the solvent with the dendrimer is at the periphery which has a higher concentration of polar OH groups, and it does not interfere significantly with their ability to self-associate. Using these dendrimers as templates, a simple methodology in which silver nanoparticles are synthesized in one pot reaction, has been developed. The dendrimer structure provides reactive peripheral hydroxyl groups as well / Ce master présente la synthèse et la caractérisation détaillée de dendrimères symétriques constitués d'un noyau bifonctionnel linéaire (2-butyne-1,4-diol) et de dendrons formés à partir de l'alcool 3,5-dihydroxybenzylique. La construction divergente, couche-par-couche de ces dendrimères en forme d'haltères est basée sur une simple hydrolyse acido-basique entre l'aminosilane Me2Si(NMe2)2 et les molecules possédant des groupements hydroxyles terminaux. Certaines propriétés physiques de ces dendrimères ont été explorées afin de mieux comprendre leurs applications potentielles. Notamment, nous avons démontré que l'auto- assemblage de ces dendrimères en agrégats dépend du nombre de génération, de leur structure et du solvant. En effet, les dendrimères de générations 1 à 3 forment des agrégats à une concentration critique d'agrégation plus élevée que celle des dendrimères de génération 4 dans le THF. Ce phénomène est dû à la structure plutôt ouverte des dendrimères de basse génération qui possèdent un noyau linéaire devenant prédominant dans le phénomène d'auto-assemblage. Par contre, les dendrimères de génération 4 adoptent une architecture plus globulaire qui favorisent les liaisons hydrogène et facilitent leur auto assemblage à basses concentrations. Dans l'eau, les dendrimères générations 1 et 2 forment des agrégats en minimisant leurs forces répulsives, ce solvant plus polaire ne pouvant que très peu interagir avec les noyaux aromatiques constituant les dendrons. Dans le cas des dendrimères de générations 3 et 4, le solvant interagit principalement avec les groupes hydroxyles terminaux présents à plus haute concentration, et ceci n'influence pas de manière sig

A new methodology using simple acid-base hydrolysis of aminosilanes with molecules containing terminal hydroxyl groups, has been developed for the preparation of supports for heterogenized homogeneous catalysis. The flexibility of this approach has allowed the build-up of new materials ranging from simple organometallic thin films to complex organometallic-inorganic sol-gel networks, and organophosphine and metallodendrimers. The acid-base hydrolytic route to construct thin films containing phosphine and amine donor ligands on glass surfaces, eliminates the problems of the traditional surface functionalization techniques. Surface modification involves the reaction of SiCl4 with the surface hydroxyl groups of glass, quartz and single crystal silicon, followed by the addition of NEt2H, resulting in the formation of [Si]-NEt2 sites on the surface, which can undergo acid-base hydrolysis with phosphine and amine ligands containing terminal OH groups, to afford thin films of various long alkane chains containing terminal donor ligands. Bridge-splitting and ligand displacement reactions were used to anchor the organometallic complexes of Ni(0), Rh(I), Ru(II) and Pd(0). A detailed analysis of their characterization is reported. The catalytic efficiencies were examined for the cyclooligomerization of phenylacetylene using the thin film, [Si]-O-(CH 2)3PPh2Ni(CO)2PPh3, and the hydrogenation of diphenylacetylene with the long alkane chain thin film, [Si]-O-(CH2)nPPh2Rh(1,5-C8H 12)(Cl) (n = 10--12). Both anchored catalysts were highly active and selective, resulting in product distributions that differed from similar reactions with solution complexes. / In an attempt to prepare solution analogs to the surface-bound species, an interesting class of Rh(I) complexes of the type, Rh(CO)(Cl)(PPh3 )(NRR'R″) were synthesized, of which Rh(CO)(Cl)(PPh3)(HNEt2) and Rh(CO)(Cl)(PPh 3)(H2NCy) were crystallographically characterized. Reactivity of the complex, Rh(CO)(Cl)(PPh3)(HNEt2) towards haloalkanes was also explored, resulting in Rh(III) amine anionic complexes of the type, [RhX4(CO)(PPh3)]-(H2NEt 2)+. X-ray structural characterization of the Rh(III) complexes are discussed. The catalytic reactivity of Rh(CO)(Cl)(PPh3 )(HNEt2) in the hydrosilation of 1-hexene, shows higher activity than both Rh(CO)(Cl)(PPh3)2 and RhCl(PPh3) 3. In the presence of CCl4, Rh(CO)(Cl)(PPh3)(HNEt 2), was able to polymerize styrene and methyl methacrylate. / An alternative approach to sol-gel processing, based on acid-base hydrolysis, was used to develop organometallic network supports. The organometallic-inorganic sol-gel was prepared in an non-aqueous medium, under mild reaction conditions, using commercially available reagents, eliminating many of the problems related to the traditional sol-gel technique. The organometallic-inorganic hybrid network catalyzed tolan hydrogenation with selectivities for the fully hydrogenated product, bibenzyl. / In the final part of the study on supported catalysis, tri-branched organophosphine and metallo-dendrimers are prepared in excellent yields via acid-base hydrolytic chemistry. The organophosphine dendrimers are used to subsequently bind the Rh(I)(COD)(Cl) complex. An examination of the 31P NMR and MALDI data suggests dendrimer growth. The Rh(I) dendrimers were employed as catalysts for decene hydrogenation resulting in activities similar to the monomeric adduct.

The effect of high external pressures on the Raman spectra of various metal pyrophosphate salts has been investigated with the aid of a diamond-anvil cell and a Raman microspectrometer. The pressure dependences of the Raman-active bands were determined from the wavenumber vs. pressure plots. The KMHP2O7·2H2O [M = Co(II), Mn(II), Zn(II) and Mg(II)] series of salts was studied at pressures up to about 50 kbar (ca. 50,000 atm). The Co(II) salt displayed an irreversible, pressure-driven, structural transformation at around 29 kbar. The M4(P2O 7)2·10H2O [M = Zn(II) and Mn(II)] salts were also investigated. A reversible phase transition was observed to take place for the Zn(II) salt in the pressure range of 15-20 kbar. Three other pyrophosphate materials, K4P2O7, Co 2P2O7·6H2O and Ca2KH 3(P2O7)2·3H2O, were also examined at high-pressure, but no pressure-driven phase transitions were observed in these cases.

Two systems for rhodium nanoparticle (Rh NP) synthesis were examined. A series of traditional organic ligands, such as triphenylphosphine or bipyridine (bipy), in THF were employed during the reduction of Rh(allyl)3, a "salt-free" metal precursor, using H2(g) as reducer. These ligands, employed in excess, afforded Rh NPs, but failed to produce mono-dispersed samples. The Rh NPs obtained failed to catalyze the arene hydrogenation reaction and resulted in large aggregates under catalytic conditions. To explore other stabilization methods, Rh NPs stabilized by phosphine functionalized ionic liquids (FILs) were prepared in [BDMI]NTf2 (BDMI = 1-butyl-2,3-dimethylimidazolium, NTf2 = bis(trifluoromethanesulfonyl)imide) using H2(g) (4 bars) as a reducer. The Rh(allyl)3 precursor proved to be a better choice than the usual RhCl3 precursor, which could not produce long-lasting, stable particles under catalytic conditions. The synthesized FIL stabilized Rh NPs proved to be active biphasic catalysts for the hydrogenation of toluene, styrene and xylenes under mild conditions (75ºC, 40 bar H2(g), 3h). The impact on activity of the length of the spacer between the phosphine function and the ionic liquid moiety in the FIL was studied. The Rh NPs stabilized by FILs showed higher catalytic activity and recyclability than NPs synthesized in the absence of a stabilizer and more stable than the system employing triphenylphosphine in [BDMI]NTf2 as a stabilizer. The size of the stabilized Rh NPs was measured to be around 2 nm by TEM, while those produced in the absence of a FIL stabilizer formed only aggregates. / Deux systèmes pour la synthèse de nanoparticules de rhodium (NPs Rh) ont été examinés. Plusieurs ligands classiques, comme la triphenylphosphine ou la bipyridine (bipy), ont été employés dans le THF pour la réduction de Rh(allyl)3, un précurseur métallique ne générant pas de sel, en utilisant H2(g) comme réducteur. Ces ligands, placés en large excès, ont permis d'accéder à des NPs Rh, mais n'ont pu permettre l'obtention d'échantillons monodisperses de petites particules. Dans tous les cas, les NPs Rh obtenues n'ont pu catalyser la réaction d'hydrogénation des arènes et ont formé de larges aggrégats en conditions catalytiques. Pour étudier d'autres méthodes de stabilisation, des NPs Rh, stabilisées par des liquides ioniques fonctionnalisés avec un groupement phosphine (LIFs), ont été préparées dans le [BDMI]NTf2 (BDMI = 1-butyl-2,3-dimethylimidazlium, NTf2 = bis(trifluoromethanesulfonyl)imide) sous pression d'H2(g) (4 bars) comme réducteur. Le précurseur Rh(allyl)3 s'est révélé être un meilleur choix que le précurseur classique, RhCl3, qui conduit à des particules instables dans le temps, dans les conditions de la catalyse. Ces NPs Rh se sont révélées être actives en catalyse d'hydrogénation du toluène, du styrène et des xylènes en conditions douces (75ºC, 40 bar H2(g), 3h). L'effet sur l'activité de la longueur de l'espaceur entre la phosphine et la fonction imidazolium dans le LIF a été étudié. Les NPs Rh stabilisées par des LIFs se sont avérées les plus actives en catalyse. Leur recyclabilité est supérieure à celle des systèmes sans stabilisants. Elles sont également plus stables que le système avec la triphenylphosphine comme stabilisant dans le [BDMI]NTf2. La taille des NPs Rh a été mesurée à 2nm par TEM, alors que le système sans stabilisation n'a produit que des agrégats.

Several series of platinum(II) based complexes have been synthesized. The ligands used include halides and sulfoxides, but also pyrazine and 2,5-dimethylpyrazine. Both diazines were also employed as bridging ligands to prepare dimeric compounds, such as trans,trans-Pt(TMSO)Cl2(pz)Pt(R2SO)Cl2 or trans,trans-{Pt(DEtSO)Cl2}2(pz). The complexes have been characterized by IR, Raman and multinuclear magnetic resonance spectroscopies (1H, 13C and 195Pt). 195Pt-NMR spectroscopy, a key technique of this project, has been studied more in details in the form of a review paper. The reaction of 2,5-dimethylpyrazine with K[Pt(R2SO)Cl3] has been investigated and the crystal structures of two dimeric complexes, trans,trans-{Pt(DEtSO)Cl2}2(Me2pz) and trans,trans-{Pt(DBuSO)Cl2}2(Me2pz), were determined. Pyrazine was also employed in monomeric compounds, such as cis- Pt(R2SO)(pz)I2, cis-Pt(pz)2X2 and trans-Pt(pz)2X2, (X = Cl, I, Br, NO2) and trans- Pt(DEtSO)(pz)Cl2. / Plusieurs séries de complexes de platine(II) ont été synthétisées. Les ligands employés pour ces synthèses incluent des halogénures, des sulfoxydes, mais aussi la pyrazine et la 2,5-dimethylpyrazine. Les deux diazines ont également été utilisées comme ligands pontées dans la préparation de composés dimériques, tels les trans,trans-Pt(TMSO)Cl2(pz)Pt(R2SO)Cl2 et les trans,trans-{Pt(DEtSO)Cl2}2(pz). Les complexes ont, par la suite, été caracterisés par spectroscopies IR, Raman et RMN multinoyaux (1H, 13C et 195Pt). La spectroscopie RMN du platine-195, une technique clé de ce projet, a été étudiée plus en détails et a fait l'objet de la publication d'une revue. La réaction de la 2,5-dimethylpyrazine avec le complexe monosubstitué K[Pt(R2SO)Cl3] a été étudiée et la structure cristalline de deux complexes dimériques, le trans,trans-{Pt(DEtSO)Cl2}2(Me2pz) et le trans,trans-{Pt(DBuSO)Cl2}2(Me2pz), ont pu être résolues. La pyrazine a également été utilisée dans la synthèse de monomères, tells les cis- Pt(R2SO)(pz)I2, les cis-Pt(pz)2X2 et trans-Pt(pz)2X2, (X = Cl, I, Br, NO2) et les trans- Pt(DEtSO)(pz)Cl2.

No description available.

The targeting of key processes encountered in cancer may rest in the telomeres found at the end of eukaryotic chromosome. In somatic cells, with each cellular division the length of the telomere decreases, eventually reaching a critical length that signals apoptosis. Conversely in cancerous cells, the length of the telomere is maintained by the reverse transcriptase enzyme telomerase. This enzyme operates on the long single stranded extreme 3'-terminus of the telomere that consists mostly of guanine bases. There is evidence that telomerase can be inhibited by the folding of this G-rich portion of the telomere into a quadruplex structure, consisting of a planar arrangement of four guanine bases held together by a Hoogsteen hydrogen bonded array. Therefore, it is of great interest to create small molecules that bind strongly and preferentially to the G-quadruplex DNA motif for telomerase inhibition as a cancer therapy. Thus far, there have been many elegant studies on organic G-quadruplex binders that have appeared, but examples involving inorganic complexes are rare. Implementation of transition metals in these scaffolds provides the opportunity to generate G-quadruplex binders of multiple geometries beyond those that carbon can access. Comparatively speaking, introduction of metals into these scaffolds can lead to simplified syntheses of these binders over their organic counterparts with generation of compound libraries able to selectively target G-quadruplex DNA. A first generation of phenanthroimidazole platinum(II) complexes were synthesized, containing large π-surfaces that can bias their binding to G-quadruplex DNA. In comparison to a bipyridine platinum(II) complex, binding affinity and selectivity for the intermolecular Gquadruplex, (T4G4T4)4 is compared through UV-Vis titrations, thermal denaturation, competitive dialysis, circular dichroism and molecular modeling. In an attempt to place our stu / Le ciblage des mécanismes clés du cancer pourrait se situer au niveau des télomères positionnés à l'extrémité du chromosome eucaryote. La télomère raccourcis lors de la division des cellules somatiques pour atteindre éventuellement une longueur critique signalant l'apoptose. Chez les cellules cancérigènes, la longueur du télomère est maintenue par la télomérase. Cette enzyme fonctionne spécifiquement sur le simple brin d'ADN situé à l'extrémité 3'-terminal du télomère, qui est composé en majeur partie de guanines (G). Il existe des preuves que l'activité de la télomérase peut être inhibée par le repliement de cette région du télomère riche en bases G. La structure quadruplexe ainsi formée est composée d'un arrangement planaire de quatre bases guanines tenu ensemble par une pléiade de liaison d'hydrogène de Hoogsteen. Par conséquent, il est de grand intérêt pour le traitement thérapeutique du cancer de créer de molécules qui ont la capacité de se lier solidement et préférentiellement à la structure G-quadruplexe de l'ADN. Il y a eu jusqu'à présent de nombreuses études exécutées sur les molécules organiques se liant au motif G-quadruplexe. Les exemples relatifs aux ligands composés d'éléments inorganiques sont par contre plus rares. La mise en oeuvre des métaux de transition dans ces échafaudages moléculaires offre l'opportunité de générer des ligands G-quadruplexe de géométries inaccessible aux ligands organiques. Comparativement, l'introduction des métaux de transition peut simplifier la synthèse des ligands G-quadruplexe et mener à l'élaboration d'une bibliothèque de composés ayant la capacité de cibler sélectivement le motif G-quadruplex. Une première génération de complexes de phenanthroimidazole de platine (II) a été synthétisée, ayant de larges surfaces-π pouvant être ajusté lors de la liaison avec le motif G-quadruplexe.

Several reaction systems have been investigated as possible sources of diatomic sulfur (S$ sb2$). Dialkoxy disulfides have been shown to thermally decompose with the formation of sulfur likely as S$ sb2$ which was successfully trapped in modest yield. Several other systems have been shown to decompose with a likely S$ sb2$ intermediate. / The chemistry of the chloro(triphenylmethyl)sulfides was studied. The X-ray crystal structures of the first chlorodisulfide and chlorotrisulfide were obtained. The chlorotriphenylmethyl sulfides were found to decompose in the presence of 1,3-dienes to yield products which are consistent with the trapping of diatomic sulfur. The reactions of the chloro(triphenylmethyl)sulfides were examined and used to prepare a series of mixed sulfides containing 1-4 sulfurs. A novel extrusion of sulfur in the reaction of chloro(triphenylmethyl)monosulfide with thiocarbonyl compounds was investigated. The thermal decomposition of the sulfides as solids and in solution were examined. / The solvent dependent desulfurization of sulfenic sulfonic thioanhydrides was investigated in the anticipation of discovering a diatomic sulfur intermediate. The extrusion was shown to involve the concatenation of sulfur atoms until a stable sulfur ring could be extruded. / The X-ray crystal structure of bis(triphenylmethyl)disulfide was determined and was discussed in relation to other hindered disulfides.

The synthesis, characterization, and assembly of thiol-stabilized gold nanoparticles in 2- and 3-dimensions are the focus of this thesis. / Assemblies of gold nanoparticles in 2-dimensions were prepared by the reduction of gold(I)-thiolate thin films on carbon and silicon surfaces. These films were reduced by direct exposure to an electron beam. The electron beam-induced growth of gold nanoparticles was observed in-situ in a transmission electron microscope. Electron beam lithography of the gold(I)-thiolate films allowed for the fabrication of sub-50 nm arrays of small gold nanoparticles (from 2 to 6 nm in diameter). Variation in the electron dose allowed for a variation in nanoparticle surface coverage. / Novel polymer-stabilized gold nanoparticles with high grafting densities were prepared for their 3D dispersion in polymer matrices. The resulting polymer nanocomposites were characterized by transmission electron microscopy, UV-visible spectroscopy, and small angle X-ray scattering. The homogeneous blending of the nanoparticles in polymer matrices was a function of the polymeric ligand molecular weight, as well as the polymeric ligand grafting density on the gold core. The truncated octahedral shape of the gold core seems to favor the wetting of the polymer ligand brush by the polymer matrix. This in turn seems to favor the dispersion of the gold nanoparticles in the polymer matrices. / Finally, small thiol-capped gold nanoparticles were prepared by the chemical reduction of gold(I)-thiolate complexes in solution. The sizes of the resulting nanoparticles were compared to those prepared by conventional methods.

Thesis (Ph.D.)--Delft University of Technology, 2008. / Vita. Includes bibliographical references.