The synthesis of 2,4,6,8-Tetramethylcyclotetrasiloxane (D4H), and Poly(methylhydrosiloxane) (PMHS) average molecular weight 1700-3200 g/mol, were functionalized with different repeat units of methoxy polyethylene glycol (PEG) (n = 8,12,17). These compounds act as polymer electrolytes with a backbone of siloxane and they were prepared via hydro-silylation reaction to be functionalized with different molecular weights of Ally-PEG. The compounds were confirmed by FT-IR, 1H-NMR and 13C NMR spectroscopy. A hydro-silylation reaction between the functionalized AllyPEG of different molecular weights produced four compounds with a low glass transition temperature that could improve comb like polymer electrolytes conductivity by reducing crystalline phase of PEO. Another way to increase the percentage of the amorphous phase of PEO is to blend it with other polymers. The blending method is considered to be an important method to improve the ionic conductivities and dimensional stability of polymer electrolytes. The main advantages of the blend systems are the simplicity of preparation and the ease to control the physical properties. A high molecular weight of poly 2- vinyl pyridine (Mw=200,000) was added to improve the dimensional stability. Differential scanning calorimetry (DSC) thermal analysis shows that all the blend systems will exhibit an increase in the glass transition temperature by increasing the salt content. The other novel synthesis of polymer electrolytes are triglyme borane and borosilicate. They were synthesized via hydro-boration. These compounds were characterized and confirmed by FT-IR, 1H-NMR 13C NMR spectroscopy. The ionic conductivity of both systems, pure and blend, of different compositions were determined at four temperatures i.e. 25°C, 40°C, 55°C and 70°C. A maximum ionic conductivity value of the siloxane blend is 9.1x10-4 S cm-1 and the pure triglyme borane is 2.14x10-3 S cm-1 at ambient temperature. The ratios of ethylene oxide to lithium salt of siloxane blend and pure triglyme borane were 10:1 and 35:1 respectively. These ratios were the highest conductivity obtained in all the electrolyte systems. The ionic conductivity increases with increasing temperature and salt content to reach optimum concentration. This behavior results in ionic transport, which is supported by the segmental motion of the polymer matrix host.

Made available in DSpace on 2015-05-14T13:21:47Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2304381 bytes, checksum: 383faaa5d2a0cb26ce8f49ef357849d1 (MD5) Previous issue date: 2009-03-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The selective leaching of clay minerals is an important method in the preparation of porous silicates presenting as a simple, effective and low cost route. In this study, vermiculite was submitted to acid treatment at concentrations 1, 2, 3, and 4 mol dm-3, resulting the precursor solids named as VacX (x=1 a 4), respectively. The lixiviated matrices and vermiculite reacted covalently with the organosilanes aminepropyl-, propyletilenediamine-, propyldietilenetriamine- and glycidoxypropyltrimethoxisilane (GPTS). The hybrid Vac3G, derived from silanization reaction between Vac3 and GPTS, was submitted to subsequent reactions with ethyl, propyl, butyldiamines and 2- aminepiridine resulting in the entrance of new basic centres. The products were characterized by chemical analysis, infrared spectroscopy, X-ray diffraction, 29Si and 27Al NMR in solid state, SEM, and pore volume and surface area determination. The lixiviation of sodic vermiculite originated the restructured porous solids with high superficial area showing the values133, 334, 673 e 575 m2 g-1 for VacX where X = 1,2,3,4, respectively. These solids and sodic vermiculite reacted covalently with each organosilane through methoxyl groups of silane and the hydroxyl surface of matrices. Independently of solid, it was observed that the lixiviation favored the reactivity of activated matrices compared with sodic vermiculite, showing the Vac3 as more reactive comparing with others solids. All modified solids presented high nitrogen content showing the values of 6,31 %. The set of modified vermiculites containing aminepropyl group was applied as adsorbent for divalent cations as copper and nickel in aqueous solution. These solid showed highest affinity for Ni2+ than Cu2+ ions as illustrated by Nf values of 2,97 and 1,23 mmol g-1, respectively. Clay porous solids obtained of leaching treatment of vermiculite are potential substrates for grafting of silanes showing important applications as adsorbents for contaminant species as heavy metals. / A lixiviação seletiva de argilominerais é um método importante na preparação de silicatos porosos constituindo-se em uma rota simples, efetiva e de baixo custo. Neste estudo a vermiculita foi submetida a tratamento ácido com acido nítrico nas concentrações 1, 2, 3 e 4 mol dm- 3, originando os sólidos precursores denominados VacX (x=1 a 4), respectivamente. As matrizes ativadas e a vermiculita reagiram covalentemente com os organosilanos aminopropil-, propiletilenodiamino-, propildietilenotriamino- e glicidóxipropiltrimetoxissilano (GPTS) através dos grupos metoxilas do silano e as hidroxilas da superfície das matrizes. O híbrido Vac3G, derivado da silanização do Vac3 com GPTS, sofreu reações subseqüentes com as diaminas etil, propil, butildiamina e 2- aminopiridina, possibilitando a entrada de novos centros básicos. Os diversos sólidos foram caracterizados por análise química, espectroscopia na região do IV, DRX, RMN 29Si e 27Al, MEV, volume de poro e área superficial. A lixiviação da vermiculita sódica originou sólidos porosos reestruturados com elevadas áreas superficiais cujos valores foram 133, 334, 673 e 575 m2 g-1 para os sólidos Vac1, Vac2, Vac3 e Vac4, respectivamente. Independentemente do sólido, observou-se que à medida que a lixiviação se torna mais acentuada, houve um aumento na reatividade das matrizes ativadas em relação à vermiculita original, sendo a matriz Vac3 a mais reativa diante das reações aqui propostas. Todos os sólidos modificados apresentaram altos teores de grupos orgânicos incorporados. A série de vermiculitas modificadas com o grupo aminopropil foi utilizada para a adsorção de cátions divalentes de cobre e níquel em solução aquosa, mostrando maior afinidade para os íons de Ni2+ (aq) do que para Cu2+ (aq) como ilustrado pelos valores Nf de 2,97 e 1,23 mmol g-1, respectivamente. Os sólidos porosos argilosos derivados de tratamento ácido da vermiculita são substratos potenciais para imobilização de silanos apresentando importantes aplicações como adosrventes para espécies poluentes como metais pesados.

Near-infrared (NIR) light, with wavelengths of 650 to 900 nanometers, effectively penetrates tissues. The high signal to noise ratio and low phototoxicity of NIR light makes this wavelength range ideal for deep tissue imaging. However, current NIR fluorophores are generally large hydrophobic molecules that are prone to aggregation. Sulfonation can enhance aqueous solubility, but their anionic nature prevents membrane diffusion, and thus, restricts the applications of sulfonated molecules to in vitro or fixed cells. The repertoire of commercially available sulfonated NIR probes is mostly limited cyanines, which have low photostability. Moreover, larger cyanines require multiple sulfonates to maintain aqueous solubility. For example, Indocyanine Green is only sparingly soluble in PBS, despite having two sulfonates. My work has focused on the delivery of sulfonated dyes into live cells and the development of a new, ultra-compact NIR dye scaffold. First, to expand the in-cell applications of sulfonated fluorophores, I designed reductively-labile sulfonate protecting groups. Using these scaffolds, I have successfully delivered the fluorophore dansyl sulfonate into live cells, where the cytosolic reducing environment unmasks the anionic sulfonate. Secondly, to create a compact, photostable NIR fluorophore, I pioneered the discovery of azasilines dyes. The two azasiline derivatives, ASiFluor710 and ASiFluor730, fluoresce over 700 nanometers and are among the most compact NIR fluorophores currently known. ASiFluor730 also retains the high photostability of oxazine dyes, highlighting their potential in long exposure applications. Beyond the immediate applications in fluorescence microscopy and in vivo imaging, I envision that my work will serve as a framework for the future design of soluble, membrane permeable, NIR fluorescent probes.

A systematic silylation approach using mono-, di-, and trichlorosilanes with different alkyl chain lengths was employed to enhance the hydrothermal stability of zeolite Y. DRIFT spectra of the silylated zeolites indicate that the attachment of the silanes takes place at surface silanol groups. Regarding hydrothermal stability under aqueous-phase processing (APP) conditions, i.e., pH ≈ 2, 473 K and autogenous pressure, the selective silylation of the zeolite surface usingmonochlorosilanes has no considerable influence. By using trichlorosilanes, the hydrothermal stability of zeolite Y can be improved significantly as proven by a stability test in an aqueous solution of 0.2M levulinic acid (LA) and 0.6M formic acid (FA) at 473 K. However, the silylationwith trichlorosilanes results in a significant loss of total specific pore volume and total specific surface area, e.g., 0.35 cm3 g−1 and 507m2 g−1 for the silylated zeolite Y functionalized with n-octadecyltrichlorosilane compared to 0.51 cm3 g−1 and 788 m2 g−1 for the parent zeolite Y. The hydrogenation of LA to g-valerolactone (GVL) was conducted over 3 wt.-% Pt on zeolite Y (3PtY) silylated with either n-octadecyltrichlorosilane or methyltrichlorosilane using different reducing agents, e.g., FA or H2. While in the stability test an enhanced hydrothermal stability was found for zeolite Y silylated with n-octadecyltrichlorosilane, its stability in the hydrogenation of LA was far less pronounced. Only by applying an excess amount of methyltrichlorosilane, i.e., 10 mmol per 1 g of zeolite Y, presumably resulting in a high degree of polymerization among the silanes, a recognizable improvement of the stability of the 3 PtY catalyst could be achieved. Nonetheless, the pore blockage found for zeolite Y silylated with an excess amount of methyltrichlorosilane was reflected in a drastically lower GVL yield at 493 K using FA as reducing agent, i.e., 12 vs. 34% for 3PtY after 24 h.

No description available.

Thèse de doctorat : Sciences : Strasbourg 1 : 2007. / Titre provenant de l'écran-titre. Notes bibliogr.

The use of small molecule building blocks in, for example, pharmaceutical research and new material development, creates a need for new and improved organic synthesis methods. The use of transition metals as mediators and catalysts opens up new reaction pathways that have made the synthesis of completely new compounds possible as well as greatly improved the synthetic routes to known compounds. Herein, the development of new metal-mediated and catalyzed reactions for construction of vinylic and allylic carbon-carbon and carbon-heteroatom bonds is described.  The use of iodonium salts as coupling partners in Pd-catalyzed Heck type reactions with alkenes is shown to improve the current substrate scope. Results from a mechanistic study indicate that the reaction proceeds via high oxidation state palladium intermediates. The use of IIII reagents is also believed to facilitate a PdII/PdIV catalytic cycle in allylic silylation of alkenes using (SiMe3)2, which, to the best of our knowledge, is the first method developed for metal-catalyzed allylic C-H silylation. The same silyl-source, (SiMe3)2, has previously been used in a Pd-catalyzed allylic substitution reaction in which allylic silanes are formed from allylic alcohols. A detailed mechanistic investigation of this reaction is described in which by-products as well as intermediates, including the resting state of the catalyst, are identified using 1H, 11B, 19F and 29Si NMR spectroscopy. Kinetic experiments are performed that give information about the turn-over limiting step and the mechanism of the analogous borylation using B2pin2 is also investigated. Insights from this study further made it possible to improve the stereoselectivity of this reaction. Additionally, a new method for Cu-mediated trifluoromethylation of allylic halides is presented in which linear products are formed exclusively from both linear and branched allylic substrates at room temperature.  Identification of allylic fluorides as by-products during the reaction also led to the development of a similar Cu-mediated reaction for the fluorination of allylic halides. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

Une nouvelle famille de précatalyseurs à base d'lr(lll) a été découverte. La facilité de leur préparation, leur remarquable stabilité, et surtout leur excellente efficacité catalytique dans plusieurs réactions, c.-à-d. la 0-silylation d'alcools, l'hydrosilylation de fonctions CO et CN et l'activation de la liaison C-F, constituent un ensemble de propriétés que d'autres précatalyseurs organométalliques similaires connus à ce jour ne possèdent pas. Le fait le plus significatif est la mise en évidence expérimentale et théorique que les espèces catalytiques impliquées fonctionnement comme une paire de Lewis du type donneur-accepteur [lr(lll)H]-->[SiR3]. Dans ce cas le ligand silylium doit être considéré comme un ligand Z en appliquant le formalisme de Green, ce qui suggère un état d'oxidation formel de +Ill pour l'atome d'iridium. Cette thèse a contribué à une meilleure compréhension de la chimie du silylium appliquée à la chimie organométallique, et a abouti à l'émergence d'un nouveau champ de recherche qui pourra permettre l'élaboration de nouveaux précatalyseurs multicompétents. / A new family of highly active iridacyclic lr(lll) precatalysts has been discovered. Notably, these ionic iridacycles are very stable so that their handling under air whether in solution or as solid powder is possible. The relative simplicity of their molecular structures allows their preparation on gram scale through a very simple and convenient synthetic protocol. We identified important iridium-silane intermediates involved in the catalysis of various reactions, e.g. the 0-silylation of alcohols, the hydrosilylation of CO and CN functions, and the activation of the C(sp3)-F bond of fluorocarbons. Experimental and theoretical studies of these intermediates point towards a Lewis donor-acceptor structural formulation of the type [lr(lll)H]-->[SiR3]. These results constitute a significant contribution to the design of future multicompetent precatalysts, and provide an original insight to the bonding within the Si-lr-H motif by considering the silylium ion [SiR3]+ as a Z-type ligand rather than a "traditional" X ligand.

This thesis describes the synthesis and characterisation of titania photocatalysts for incorporation into a polyethylene film. Monodisperse, anatase-phase titania nanoparticles are prepared and the synthesis conditions necessary for attraction to a laponite clay support are determined. Methods of preventing agglomeration of the laponite system such as the use of a polyethylene oxide surfactant or chemical modification of the laponite plate edges with a dimethyloctyl methoxysilane are also explored. Finally, photocatalytic studies on the laponite-supported titania nanoparticles are performed, and the compatibility and photoactivity of these materials in the polyethylene film are examined.