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El desarrollo de nuevos métodos de síntesis de nanoóxidos mixtos de metales de transición empieza a experimentar un creciente interés, no sólo porque existe evidencia experimental de que la reducción del tamaño de partícula puede mejorar su comportamiento funcional, sino que puede dar lugar a comportamientos inesperados que abran nuevos campos de investigación que conduzcan al diseño de nuevos dispositivos. La flexibilidad de composiciones y estructuras que presentan estos óxidos complejos es el reclamo fundamental para que un cada vez mayor número de grupos de investigación dirijan sus esfuerzos a la nanosíntesis de nuevos materiales con estequiometrías cada vez más complejas. Además de las dificultades intrínsecas de obtener cualquier compuesto con un tamaño de partícula muy reducido, la nanosíntesis de óxidos complejos se enfrenta a una serie de complicaciones adicionales comparada con la de partículas metálicas o compuestos binarios. Los óxidos complejos pueden contener varios iones de metales de transición en diferentes estados de oxidación y diferentes entornos de coordinación que pueden dar lugar a diferentes tipos de acomodación de las variaciones de composición. Por lo tanto, la obtención de una estructura concreta, con una composición determinada y con todos los elementos en el estado de oxidación y el índice de coordinación adecuados, requiere de un preciso control de todas las variables que gobiernan la síntesis. De acuerdo con estas ideas, el trabajo recogido en esta tesis, se dirige al desarrollo de nuevas rutas sintéticas para la obtención de nanoóxidos funcionales..., The development of new synthesis methods for mixed transition metal nano-oxides has been intensively studied over the last decades, not only for the experimental evidences of the improvement of their functional behaviour, but also because the particle size reduction could provoke the appearance of unexpected demeanours that would open new research fields which could drive to new applications and novel devices. The compositional and structural flexibility of complex oxides lure a growing number of research groups into the nano-synthesis of increasingly complex mixed transition metal oxides. Besides the common difficulties of particle size reduction in any system, complex oxides nano-synthesis faces some additional issues compared to metallic and binary oxide nanoparticles. Complex oxides can include various transition metals in different crystallographic positions, with diverse coordination environments, or different oxidation states which could lead to many different structures. Therefore, synthesizing one particular structure, with one particular composition, and all elements in the correct oxidation state and coordination index, requires a precise and careful control of all synthesis parameters. Following these ideas, the work presented in this thesis is focused on the development of new synthetic routes for the production of functional nano-oxides...

El desarrollo de nuevos métodos de síntesis de nanoóxidos mixtos de metales de transición empieza a experimentar un creciente interés, no sólo porque existe evidencia experimental de que la reducción del tamaño de partícula puede mejorar su comportamiento funcional, sino que puede dar lugar a comportamientos inesperados que abran nuevos campos de investigación que conduzcan al diseño de nuevos dispositivos. La flexibilidad de composiciones y estructuras que presentan estos óxidos complejos es el reclamo fundamental para que un cada vez mayor número de grupos de investigación dirijan sus esfuerzos a la nanosíntesis de nuevos materiales con estequiometrías cada vez más complejas. Además de las dificultades intrínsecas de obtener cualquier compuesto con un tamaño de partícula muy reducido, la nanosíntesis de óxidos complejos se enfrenta a una serie de complicaciones adicionales comparada con la de partículas metálicas o compuestos binarios. Los óxidos complejos pueden contener varios iones de metales de transición en diferentes estados de oxidación y diferentes entornos de coordinación que pueden dar lugar a diferentes tipos de acomodación de las variaciones de composición. Por lo tanto, la obtención de una estructura concreta, con una composición determinada y con todos los elementos en el estado de oxidación y el índice de coordinación adecuados, requiere de un preciso control de todas las variables que gobiernan la síntesis. De acuerdo con estas ideas, el trabajo recogido en esta tesis, se dirige al desarrollo de nuevas rutas sintéticas para la obtención de nanoóxidos funcionales...

Chondroitin-4-sulphate (ChS A) was immobilized by matrix assisted pulsed laser evaporation (MAPLE) with the aid of a UV KrF* excimer laser source. Distilled water was used as solvent for the preparation of the frozen composite MAPLE targets. The surface morphology, chemical structure and functional properties of laser transferred ChS A were investigated as a function of laser processing conditions. The results indicate that the amount of laser immobilized material, structure, and functional properties can be controlled by the laser fluence value used for the irradiation of the MAPLE targets. Under selected irradiation conditions besides the molecular structure, the functional properties of the laser processed ChS A molecules can be maintained. © 2012 Elsevier B.V.

A novel one-step approach for designing non aggregated silica-based mesostructured therapeutic vectors is presented. Evaporation Induced Self Assembly was used in combination with amphiphilic drugs for preparing already loaded class I and class II hybrid materials containing from 50 to 60 wt% (up to 75 vol%) of drug. A good mesostructuration was able to promote an interfacial control of the drug release in PBS medium with a complete absence of the initial burst release very often described in literature for water soluble drug release experiments. The investigation of both release mechanisms and matrix dissolution was conducted via in situ ellipsometry and NMR. It proved that the nature of the drug/matrix interaction, the chemical composition of the drug/matrix interface, as well as the mesostructuration quality parameters must be taken into account at the same time for tuning the drug release rate, while maintaining the dissolution rate of silica at a reasonable level for limiting its toxicity. It proved also that non-calcined as made silica-based class I hybrid materials can be efficiently used for tuning drug release kinetics from one hour to day scale

Nanocrystalline porous N-doped ceria films have been prepared by combining sol-gel chemistry, evaporation-induced self-assembly (EISA), flash crystallization and treatment in NH 3 gas between 550 and 700 °C at flow rates of 270 and 670 cm 3 min -1. The maximum nitrogen uptake is 0.06 moles per Ce, observed for the sample treated at 600 °C and NH 3 flow rate of 670 cm 3 min -1. Nitrogen bonding to cerium is proved by XPS, through the observation of the characteristic Ce-N feature at ∿397 eV. Microstructural characterization shows that the mesostructure of the films is lost for treatment temperatures in ammonia higher than 550 °C but the porous fraction remains between 35 and 40% after ammonolysis for all the samples. The nitrided films show photocatalytic activity under visible light in the acetaldehyde decomposition, with the best results obtained for the films treated at 550 °C under NH 3 flow rate of 670 cm 3 min -1. © 2012 The Royal Society of Chemistry.

The vapor sorption properties of multilayers made of ordered mesoporous thin films with tailored composition and mesostructure are herein investigated. Optical reflectance measurements versus partial pressure of several vapors are performed to analyze the interplay between the affinity to and the accessibility of the different types of layers in the structure. We find that the behavior of a mesoporous oxide layer within the multilayer largely differs from that of the isolated thin film, its sorption properties being determined by the interaction with neighboring films. An explanation of the phenomena observed in these complex systems is provided in terms of the pore size, the affinity of each type of layer to specific compounds, and the effect of neighboring layers in the sorption properties of bilayers by an independent environmental ellipsometric study. © 2008 American Chemical Society.

The field of hybrid organic-inorganic materials has reached a stage of ripeness that is beginning to make possible extraordinary new developments. On the one hand the field has witnessed a trend towards the design of functionality in hybrids materials, while broadening spectacularly the variety of hybrid combinations explored. On the other hand, improved understanding and control of the chemistry, processing and microstructure of these versatile nanocomposite systems announce a new landscape of opportunities in dealing with increasingly complex chemistries and materials.

Here, a team of highly renowned experts gives an in-depth overview of the many fascinating facets of this field, illustrating the superiority of well-designed hybrid materials over conventional materials, and their potential applications as structural or functional materials in various fields., From the contents Hybrid Materials, Functional Applications - An Introduction Organic-Inorganic Materials - From Intercalation Chemistry to Devices Bridged Polysilsesquioxanes - Molecular-Engineering Nanostructured Hybrid Organic-Inorganic Materials Porous Inorganic-Organic Hybrid Materials Optical Properties of Functional Hybrid Organic-Inorganic Nanocomposites Electrochemistry of Sol-Gel Derived Hybrid Materials Multifunctional Hybrid Materials Based on Conducting Organic Polymers - Nanocomposite Systems with Photo-Electro-Ionic Properties and Applications Layered Organic-Inorganic Materials - A Way Towards Controllable Magnetism Building Multifunctionality in Hybrid Materials Hybrid Organic-Inorganic Electronics Bioactive Sol-Gel Hybrids