Les cryptophanes sont des molécules sphériques pouvant encapsuler dans leur cavité lipophile des molécules neutres (halogénométhanes, xénon) mais aussi des espèces ioniques comme les cations césium et thallium. Notre objectif a été d’immobiliser ces cages moléculaires de manière covalente sur un support solide dans le but de créer un matériau capable d’extraire des cations toxiques comme le thallium en milieu aqueux. Différentes stratégies ont été envisagées pour optimiser l’immobilisation de dérivés du cryptophane-A sur des surfaces de silice et d’or (surfaces planes et nanoparticules magnétiques de type coeur-écorce). Les cryptophanes-A mono-acide (1) et hexa-acide(2) ont été immobilisés sur des surfaces de silice préalablement fonctionnalisées par des groupements amines. Le cryptophane-A alcanethiol (3), ainsi que les cryptophanes 1 et 2 modifiés par lacystéamine (respectivement 4 et 5) ont été immobilisés sur des surfaces d’or. La caractérisation des surfaces planes par spectroscopie infrarouge de réflexion-absorption par modulation de polarisation(PM-IRRAS) a permis d’estimer le taux de recouvrement des différentes monocouches de cryptophanes et, ainsi, d’évaluer la méthode d’immobilisation la plus efficace. Un taux de recouvrement proche de 100% a été obtenu pour le cryptophanes 3 immobilisé sur les surfaces d’or.Ce composé a également été immobilisé de façon très efficace sur des nanoparticules magnétiques(γ-Fe2O3/SiO2) enrobées d’une nano-écorce d’or. Ces résultats permettent d’envisager la synthèse d’un cryptophane portant cinq fonctions hydroxyles et une fonction thiol afin de créer des matériaux capables d’extraire des cations toxiques. / Cryptophanes are spherical molecules that can encapsulate neutral molecules(halogenomethanes, xenon), and ionic species like cesium and thallium cations in their lipophiliccavity. Our objective was to covalently immobilize these molecular cages onto solid substrates tocreate a material able to extract toxic cations such as thallium in aqueous media. Different strategieswere considered to optimize the immobilization of cryptophane-A derivatives onto silica and goldsurfaces (flat surfaces and core-shell magnetic nanoparticles). Mono-acid cryptophane-A (1) andhexa-acid cryptophane-A (2) were immobilized onto silica surfaces that were functionalized by aminogroups beforehand. Alcanethiols cryptophane-A (3), 1 and 2 modified by cysteamine (cryptophanes 4and 5 ,respectively) were immobilized onto gold surfaces. Flat surfaces were characterized bypolarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to estimate thesurface coverage of different cryptophane monolayers and to evaluate the most effective method. Asurface coverage close to 100% was obtained for the cryptophane 3 immobilized onto gold surfaces.This compound has been also immobilized efficiently onto magnetic nanoparticles (γ-Fe2O3/SiO2)coated with gold nano-shell. These results allow to consider the synthesis of cryptophane bearing fivehydroxyl and one thiol functions to create materials able to extract toxic cations

Deux approches potentiellement anti-tumorales, employant des nanoparticules magnétiques (NPMs) et des champs magnétiques oscillants, furent étudiées. La première, l’hyperthermie magnétique, utilise l’échauffement de NPMs au contact des cellules tumorales provoqué par un champ magnétique alternatif haute-fréquence. Durant cette thèse, il fut démontré que les forces magnéto-mécaniques induites par les inhomogénéités de champ magnétique pendant un essai d’hyperthermie magnétique n’avaient aucune influence sur la viabilité cellulaire. Egalement, des mesures magnétiques, d’XPS, et de puissance de chauffe de NPMs de fer enrobées d’une coquille de silice amorphe furent effectuées et analysées. Il fut observé que cette coquille permettait de préserver les propriétés magnétiques des NPMs suite à l’exposition à un environnement aqueux. La deuxième approche anti-tumorale utilise des NPMs soumises à un champ magnétique basse-fréquence, induisant une stimulation mécanique des cellules tumorales. Une étude théorique complète de l’influence du champ magnétique, de l’agitation thermique et des interactions magnétiques sur la force magnéto-mécanique exercée par des NPMs, fut effectuée. Elle démontra notamment que cette force augmente de manière drastique pour une assemblée de NPMs lorsque la rotation du champ magnétique induit une rupture de symétrie dans l’évolution temporelle du couple magnéto-mécanique. Expérimentalement, il fut développé différents prototypes de génération de champ magnétique tournant à basse fréquence. Des tests in vitro furent réalisés en utilisant des NPMs enrobées par une matrice de phosphatidylcholine, leur permettant d’être solidaires des membranes cellulaires. Suite à la rotation d’un champ magnétique de 40 ou 380 mT, à 10 Hz, il fut observé une réduction de la survie cellulaire. / Two anti-tumor treatments based on magnetic nanoparticles (MNPs) and oscillating magnetic field were studied. The first one, magnetic hyperthermia, uses the heat released by MNPs in contact with tumor cells under a high frequency alternating magnetic field. We have shown that the forces induced by magnetic field inhomogeneity during magnetic hyperthermia essay no influence on cellular viability. Moreover, magnetic measurements, XPS characterization and heating power evaluation of iron MNPs coated by amorphous silica shell were carried out. It was observed that this shell is able to preserve the MNP magnetic properties submitted to an aqueous environment. The second anti-tumor treatment combines MNPs and low-frequency magnetic field, inducing mechanical stress to tumor cells. A complete theoretical study on the influence of magnetic field, thermal agitation and magnetic interaction on the magneto-mechanical forces generated by the MNPs was carried out. It was demonstrated that for a MNP assembly this force increases dramatically when the rotation of the magnetic field induces a break of time reversal symmetry on the magneto-mechanical torque. Experimentally, several devices generating low frequency rotating magnetic fields were developed. Using these devices, in-vitro essays were also achieved using phosphatidylcholine coated MNPs, which bind to cellular membranes. An application of a 40 or 380 mT magnetic field rotating at 10 Hz reduced cell survival rate.

A major challenge of cancer treatment is successful discrimination of cancer cells from healthy cells. Nanotechnology offers multiple venues for efficient cancer targeting. Magnetoelectric nanoparticles (MENs) are a novel, multifaceted, physics-based cancer treatment platform that enables high specificity cancer targeting and externally controlled loaded drug release. The unique magnetoelectric coupling of MENs allows them to convert externally applied magnetic fields into intrinsic electric signals, which allows MENs to both be drawn magnetically towards the cancer site and to electrically interface with cancer cells. Once internalized, the MEN payload release can be externally triggered with a magnetic field. MENs uniquely allow for discrete manipulation of the drug delivery and drug release mechanisms to allow an unprecedented level of control in cancer targeting. In this study, we demonstrate the physics behind the MEN drug delivery platform, test the MEN drug delivery platform for the first time in a humanized mouse model of cancer, and characterize the biodistribution and clearance of MENs. We found that MENs were able to fully cure the model cancer, which in this case was human ovarian carcinoma treated with paclitaxel. When compared to conventional magnetic nanoparticles and FDA approved organic PLGA nanoparticles, MENs are the highest performing treatment, even in the absence of peripheral active targeting molecules. We also mapped the movement through peripheral organs and established clearance trends of the MENs. The MENs cancer treatment platform has immense potential for future medicine, as it is generalizable, personalizable, and readily traceable in the context of treating essentially any type of cancer.

L'objectif de cette étude consiste à développer des électrodes modifiées à base des nanomatériaux à visées électroanalytiques. Pour ce faire, différentes méthodes de modification des électrodes ont été proposées à savoir la fonctionnalisation chimique, par adsorption et par électropolymérisation, en se servant des interactions électrostatiques et covalentes entre les surfaces des électrodes et les nanomatériaux (les nanoparticules magnétiques, les nanoparticules d'or, les polyoxométallates et les nanotubes de carbone). Les électrodes modifiées préparées ont permis de réaliser des dispositifs de détection (capteurs et biocapteurs) caractérisés par des performances analytiques intéressantes en termes de sensibilité et limite de détection. Des biocapteurs d'urée, à base d'électrodes semiconductrices, fonctionnalisées par des nanoparticules magnétiques portant l'enzyme uréase, ont permis d'obtenir de grandes sensibilités de détection de l'urée. Des capteurs chimiques pour la détection sensible de l'ion nitrite ont été obtenus en fonctionnalisant des électrodes de carbone vitreux et de diamant dopé au bore par des polyoxométallates. La combinaison de deux types des nanomatériaux (nanotubes de carbone et polyoxométallates hybrides) a permis l'obtention d'une structure originale qui présente les propriétés conductrices des nanotubes et électrocatalytiques des polyoxométallates. Ces structures originales ont permis la réalisation de biocapteurs enzymatiques de haute sensibilité pour la détection du glucose et du catéchol / The objective of the study consists in the development of modified electrodes, based on nanomaterials for electroanalytical applications. In this aim, different methods of modification of the electrodes have been proposed: chemical functionalization, adsorption and electropolymerization, using the electrostatic and covalent interactions between electrode surfaces and nanomaterials (magnetic nanoparticles, gold nanoparticles, polyoxometallates and carbon nanotubes). The prepared modified electrodes have allowed the obtaining of detection devices (sensors and biosensors) characterized for their interesting analytical performances in terms of sensitivity and detection limit. Urea biosensors, based on semi-conducting electrodes, functionalized with magnetic nanoparticles coated with urease enzyme, have allowed the sensitive detection of urea. Chemical sensors for the sensitive detection of nitrite ion have been obtained through functionalization of glassy carbon electrodes and boron doped diamond electrodes with polyoxometallates. The combination of both types of nanomaterials (carbon nanotubes and hybrid polyoxometallates) have allowed the obtaining of an original structure that presents conductive properties of nanotubes and electrocatalytic properties of polyoxometallates. These original structures have allowed the fabrication of enzymatic biosensors with a high sensitivity for the detection of glucose and catechol

O câncer é uma das maiores causas de mortalidade no Brasil e no mundo, com potencial de crescimento nas próximas décadas. Um tipo de tratamento promissor é a hipertermia magnética, procedimento no qual as células tumorais morrem pelo efeito do calor gerado por partículas magnéticas após a aplicação de campo magnético alternado em frequências adequadas. Tais partículas também são capazes de atuar como agentes de contraste para imageamento por ressonância magnética, um poderoso método de diagnóstico para identificação de células neoplásicas, formando a combinação conhecida como theranostics (terapia e diagnóstico). Neste trabalho foram sintetizadas nanopartículas de óxido de ferro por método de coprecipitação com posterior encapsulação por técnica de nano spray drying, visando sua aplicação no tratamento de câncer por hipertermia e como agente de contraste para imageamento por ressonância magnética. Para a encapsulação foram utilizadas matrizes poliméricas de Maltodextrina com Polissorbato 80, Pluronic F68, Eudragit® S100 e PCL com Pluronic F68, escolhidos com o intuito de formar partículas que dispersem bem em meio aquoso e que consigam atingir alvo tumoral após administração no corpo do paciente. Parâmetros de secagem pelo equipamento Nano Spray Dryer, como temperatura, solvente e concentração de reagentes, foram avaliados. As partículas formadas foram caracterizadas por Microscopia Eletrônica de Varredura, Difração de Raios-X, Análise Termogravimétrica, Espalhamento de Luz Dinâmico, Espectroscopia de Infravermelho, magnetismo quanto a magnetização de saturação e temperatura, citotoxicidade e potencial de aquecimento. Tais procedimentos indicaram que o método de coprecipitação produziu nanopartículas de magnetita de tamanho em torno 20 nm, superparamagnéticas a temperatura ambiente, sem potencial citotóxico. A técnica de nano spray drying foi eficiente para a formação de partículas com tamanho em torno de 1 &#956m, também superparamagnéticas, biocompatíveis e com propriedades magnéticas adequadas e para aplicações pretendidas. Destaca-se a amostra com Pluronic, OF-10/15-1P, que apresentou magnetização de saturação de 68,7 emu/g e interação específica com células tumorais. / Cancer is one of the greatest causes of mortality in Brazil and in the world, with growing potential for the next decades. A promising treatment alternative is magnetic hyperthermia, in which tumor cells die by the heat generated by magnetic nanoparticles after application of an alternate magnetic field in adequate frequencies. Such particles are also capable of acting as contrast agents for magnetic resonance imaging, a powerful method of diagnosis for the identification of neoplasic cells, which characterizes the combination of properties known as theranostics (therapy and diagnosis). In this work, iron oxide nanoparticles were synthesized by coprecipitation method with subsequent encapsulation by nano spray drying technique, aiming their application on cancer treatment by hyperthermia and on magnetic resonance imaging as a contrast agent. Polymeric matrices of Maltodextrin with Polysorbate 80, Pluronic F68, Eudragit® S100 and PCL with Pluronic F68 were employed for encapsulation, chosen carefully to create particles that disperse well in aqueous media and that are able to address the tumoral target after administration into the patient\'s body. Drying parameters of the Nano Spray Dryer equipment, such as temperature, dispersing medium and reagent concentrations, were evaluated. The generated particles were characterized by Scanning Electron Microscopy, X-Ray Diffraction, Thermogravimetric Analysis, Dynamic Light Scattering, Infrared Spectroscopy, by magnetism in matters of applied magnetic field and temperature, cytotoxic potential and heating potential. Such methods indicated that the coprecipitation method was able to produce magnetite nanoparticles with size of approximately 20 nm, superparamagnetic at room temperature and with no cytotoxic potential. The nano spray drying technique was efficient to produce particles with size of around 1 &#956m, biocompatible, superparamagnetic and with adequate magnetic properties for the intended applications. The sample OF-10/15-1P stands out with a saturation magnetization of 68.7 emu/g and presenting specific interactions with the tumour cells.

[pt] Nanopartículas são importantes ferramentas utilizadas em medicina, tanto para diagnóstico como para tratamento de diversas doenças. Seus tamanhos podem ser controlados, variando de dezenas até centenas de nanômetros, tornando-as menores ou comparáveis às dimensões de células, bactérias e vírus. As nanopartículas magnéticas possuem um núcleo de material magnético recoberto por camadas de diferentes materiais, incluindo sílica ou um polímero. Esta cobertura é responsável pela funcionalização, de forma que elas realizem tarefas específicas, seja para funcionar como um marcador com fins diagnósticos e/ou como um transportador de fármacos. É muito importante no processo de fabricação e utilização das nanopartículas o conhecimento de suas propriedades magnéticas. Com este objetivo, construímos um magnetômetro baseado em um criorefrigerador com capacidade para medir propriedades magnéticas em função da temperatura desde ambiente até 6 K. Como sensor magnético utilizamos um elemento Hall de GaAs de baixo custo. O magnetômetro construído tem uma configuração diferente dos magnetômetros Hall tradicionais, já que neste caso a amostra se movimenta na região do sensor. De forma a aumentar a exatidão do momento magnético obtido, foi desenvolvido um modelo que leva em consideração a geometria da amostra. A resolução está limitada pelo sensor utilizado em 10-7 Am2. O magnetômetro foi calibrado de forma independente e seu desempenho foi comparado a magnetômetros de amostra vibrante (VSM) comerciais, apresentando erros menores que 2 porcento na magnetização obtida de diversas amostras. Todos os equipamentos envolvidos na operação do magnetômetro a baixas temperaturas são controlados utilizando a linguagem LabVIEW. Na versão atual do programa, curvas M x H e ZFC-FC podem ser obtidas. Como exemplo de aplicação, fabricamos nanopartículas magnéticas com núcleo de oxido de ferro pelo processo de coprecipitação em meio alcalino e recobrimos com surfactantes e SiO2. As propriedades magnéticas das nanopartículas foram obtidas utilizando o magnetômetro construído. As nanopartículas apresentaram comportamento superparamagnético e grande potencial para liberação controlada de drogas. / [en] Nanoparticles are important tools used in medicine, for diagnosis as well as for treatment of various diseases. Their sizes can be controlled, ranging from tens to hundreds of nanometers, enabling them to interact with cells, bacteria, and viruses. Magnetic nanoparticles have a core of magnetic material coated with layers of different materials, including silica or a polymer. This coating is responsible for their functionalization, so they can carry out specific tasks serving as a marker for diagnostic purposes and / or as a carrier for drugs. The knowledge of the magnetic properties of nanoparticles is very important in the manufacturing process and their use. With this aim, we built a magnetometer based on a cryorefrigerator capable of measuring their magnetic properties as a function of temperature from room temperature to 6 K. We used a low cost GaAs Hall element as its magnetic sensor. The magnetometer built has a different configuration from the traditional Hall magnetometers, since in this case the sample moves in the region of the sensor. A model which takes into consideration the geometry of the sample was developed in order to increase the accuracy of the magnetic moment obtained. The magnetometer resolution is limited by the Hall sensor used in 10-7 Am2. The magnetometer was calibrated independently and its performance was compared to commercial vibrating sample magnetometers (VSM) showing errors smaller than 2 percent in the magnetization obtained from various samples. All the equipment involved in the operation of magnetometers at low temperatures is controlled by using the LabVIEW language. The M x H e ZFC-FC curves can be obtained in the current version. We manufactured the core with magnetic nanoparticles of iron oxide by coprecipitation process in an alkaline medium, coated with surfactants and SiO2. The magnetic properties of the nanoparticles were obtained using the magnetometer built. The nanoparticles showed superparamagnetic behavior and great potential for controlled drug release.

The idea of miniaturizing devices down to the nanoscale where quantum ffeffects become relevant demands a detailed understanding of the interplay between classical and quantum properties. Therefore, characterization of newly produced nanoscale materials is a very important part of the research in this fifield. Studying structural and magnetic properties of nano- and molecular magnets and the interplay between these properties reveals new interesting effects and suggests ways to control and optimize the respective material. The main task of this thesis is investigating the magnetic properties of molecular magnetic clusters and magnetic nanoparticles recently synthesized by several collaborating groups. This thesis contains two main parts focusing on each of these two topics. In the first part the fundamental studies on novel metal-organic molecular complexes is presented. Several newly synthesized magnetic complexes were investigated by means of different experimental techniques, in particular, by electron spin resonance spectroscopy. Chapter 1 in this part provides the theoretical background which is necessary for the interpretation of the effects observed in single molecular magnetic clusters. Chapter 2 introduces the experimental techniques applied in the studies. Chapter 3 contains the experimental results and their discussion. Firstly, the magnetic properties of two Ni-based complexes are presented. The complexes possess different ligand structures and arrangements of the Ni-ions in the metal cores. This difffference dramatically affffects the magnetic properties of the molecules such as the ground state and the magnetic anisotropy. Secondly, a detailed study of the Mn2Ni3 single molecular magnet is described. The complex has a bistable magnetic ground state with a high spin value of S = 7 and shows slow relaxation and quantum tunnelling of the magnetization. The third section concentrates on a Mn(III)-based single chain magnet showing ferromagnetic ordering of the Mn-spins and a strong magnetic anisotropy which leads to a hysteretic behavior of the magnetization. The last section describes a detailed study of the static and dynamic magnetic properties of three Mn-dimer molecular complexes by means of static magnetization, continuous wave and pulse electron spin resonance measurements. The results indicate a systematic dependence of the magnetic properties on the nearest ligands surrounding of the Mn ions. The second part of the thesis addresses magnetic properties of nano-scaled magnets such as carbon nanotubes fifilled with magnetic materials and carbon-coated magnetic nanoparticles. These studies are eventually aiming at the possible application of these particles as agents for magnetic hyperthermia. In this respect, their behavior in static and alternating magnetic fifields is investigated and discussed. Moreover, two possible hyperthermia applications of the studied magnetic nanoparticles are presented, which are the combination of a hyperthermia agents with an anticancer drug and the possibility to spatially localize the hyperthermia effffect by applying specially designed static magnetic fifields.

Le but du projet est de synthétiser un film de polymères à double mémoire de formes avec une sensibilité à la lumière ainsi qu’à un champ magnétique. Afin de rendre le polymère sensible à ces stimuli, des nanoparticules d’oxyde de fer (II,III) furent enrobées d’une couche de polydopamine. Par après, du polycaprolactone et du poly(caprolactone-co-pentadecalactone) furent synthétisés par polymérisation enzymatique à ouverture de cycle. Les polymères furent méthacrylés en fin de chaînes, remplaçant le groupe alcool par une double liaison qui est par la suite utilisée pour une réticulation. Les films de polymères étaient obtenus en combinant les nanoparticules et les polymères via une réaction click de type « thiol-ène ». Des films avec une teneur de nanoparticules de 0 à 1 pour cent en poids furent ainsi synthétisés. L’alternance entre deux formes était possible grâce à deux phénomènes physiques : l’élongation induite par cristallisation et la contraction induite par la fusion. Ces phénomènes sont causés par la fusion et la cristallisation du polycaprolactone, tandis que le poly(caprolactone-co-pentadécalactone) restait maintenu dans un état solide cristallin sur la gamme de températures étudiée. Les films de polymères changeaient de forme en étant chauffés par exposition à la lumière. Les films avec nanoparticules se contractaient quand ils étaient exposés à la lumière et retournaient à leur forme originale quand la lumière était éteinte. Le chauffage par induction avec un champ magnétique alternatif fut aussi un succès. Les films avec nanoparticules se contractaient à l’intérieur d’une bobine de cuivre avec un champ magnétique présent lorsqu’un courant électrique circulait dans la bobine. Les films retournaient à leur forme d’origine lorsque le champ magnétique était coupé. Il fut observé que plus la teneur en nanoparticules au sein du film de polymères était élevée, le plus court le temps de réponse était avant qu’un mouvement de contraction ne soit observé. Aucun changement de volume ne fut observé en chauffant des échantillons de films de polymères de 20 à 60 °C, confirmant, dans les conditions actuelles d’évaluation, que la contraction induite par la fusion et que l’élongation induite par cristallisation se produisent sans causer un changement de volume du film. / The project goal is to synthesize a two-way shape memory polymer that is both magnetically and light responsive. To make the polymer responsive to these stimuli, iron oxide (II, III) nanoparticles with a polydopamine coating were first synthesized. Afterwards, polycaprolactone and poly(caprolactone-co-pentadecalactone) were synthesized by enzymatic ring-opening polymerization. The polymer was then methacrylated at the terminal positions, replacing the alcohol with a double bond which was then used for crosslinking. Polymer films were prepared by combining the nanoparticles and the polymer by a “thiol-ene” click reaction. Films containing from 0 to 1 weight percent of nanoparticles were synthesized. Switching between the two shapes was possible by two physical phenomena: crystallization induced elongation and melting induced contraction. These are caused by the fusion and crystallization of the polycaprolactone network, while the poly(caprolactone-co-pentadecalactone) is consistently maintained in its crystalline solid state in a specific temperature range. The polymer films changed shapes due to heating when exposed to light. Films with nanoparticles contracted when exposed to light and they returned to their original form when the light was turned off. Induction heating with an alternating magnetic field was also successful. The polymer film with magnetic nanoparticles contracted inside a copper coil when the magnetic field was generated by applying electric current to the coil. The film returned to its original shape when the magnetic field was turned off. It was found that the higher the content of nanoparticles in the polymer filler, the shorter the response time was before a contraction movement was observed. No change in the polymer volume during heating of a film sample from 20 to 60 °C was observed, confirming that melting induced contraction and crystallization induced elongation occurred without change in volume under conditions examined.

[pt] A pesquisa aponta para a possibilidade de realizar a reação de redução de CO2 (CO2RR) para a formação de nanomateriais de carbono por ablação a laser pulsado(PLA) de alvos magnéticos de Ferro(Fe) e Níquel(Ni) em água pura deionizada. Os materiais coloidais sintetizados foram caracterizados por diferentes técnicas de espectroscopias ópticas (UVVis, ICP-MS, FTIR e Raman) e microscopia eletrônica de transmissão (TEM), revelando a presença de nanopartículas de óxidos e hidróxidos de metais de transição, junto com nanomaterial orgânico. Esse último, é bem visível por TEM, espectroscopia de raio-X por dispersão em energia (EDS), espectroscopia por perda de energia de elétrons (EELS), e espectroscopia Raman, que indica a presença de carbono amorfo grafítico e vibrações CH. No caso do nanomaterial obtido do Níquel, os resultados FTIR confirmam a presença da fase do hidróxido beta-Ni(OH)2, enquanto as medidas Raman e TEM sugerem também a presença de nano-folhas de Ni(HCO3)2. Os resultados experimentais foram enfim discutidos no contexto da origem e da evolução de moléculas simples e complexas de interesse astroquímico, com foco especial nas espécies potencialmente formadas na superfície de pequenos corpos metálicos do Sistema Solar e grãos de poeira cósmica do meio interestelar. / [en] The proposed research points to the possibility to perform CO2 reduction reaction (CO2RR) to solid carbon nanomaterials by the pulsed laser ablation (PLA) of magnetic target of iron (Fe) and nickel (Ni) in pure deionized water. The synthesized colloidal dispersions were characterized by different optical spectroscopies (UV-Vis, ICP-MS, FTIR and Raman) and transmission electron microscopy (TEM), revealing the presence of nanosized transition metal oxide and hydroxide nanoparticles, together with organic nanomaterial. The latter is well visible by TEM, energy-dispersive X-Ray spectroscopy (EDS), electron energy-loss spectroscopy(EELS), and Raman spectroscopy, which indicates the presence of amorphous graphitic carbon and CH vibrations. In the case of Ni derived nanomaterial, FTIR results confirm the presence of a beta-Ni(OH)2 hydroxide phase, while Raman and TEM measurements suggest also the presence of Ni(HCO3)2 nanosheets. The experimental results were finally discussed in the frame of the origin and evolution of simple and complex molecules of astrochemical interest, with special focus on those species potentially formed on the surface of metallic minor bodies in the solar system and cosmic dust grains in the interstellar medium(ISM).

[ES] La presente tesis doctoral se desarrolla en el ámbito de la catálisis, la cual está enmarcada dentro del concepto de Química Sostenible. En concreto, la investigación se ha centrado en el desarrollo y aplicación de nuevos catalizadores basados en nanopartículas metálicas coloidales y soportadas para llevar a cabo reacciones de interés. Todas las MNPs sintetizadas en esta tesis doctoral se llevaron a cabo a partir de la aproximación organometálica, donde generalmente se descompone un precursor organometálico bajo condiciones suaves de reacción y en presencia de un agente estabilizador (molécula orgánica o soporte). En el Capítulo 4 de la tesis, se ha descrito el primer ejemplo de estabilización de Ru NPs con una nueva familia de ligandos policíclicos aromáticos no planos, denominados nanografenos (hept-HBC). Específicamente, se han utilizado dos tipos distintos de nanografeno distorsionado: i) uno funcionalizado con un grupo carbonilo, y ii) otro funcionalizado con una grupo metileno en la misma posición (Ru@1 y Ru@2, respectivamente). Gracias a la similitud con los sistemas basados en MNPs soportadas en grafeno o derivados, este material puede utilizarse como referencia para estudiar los modos de coordinación y las dinámicas de estos con la superficie de la nanopartícula. A partir de un estudio combinado teórico/experimental se ha demostrado que la curvatura de los nanografenos hept-HBC es crucial para la estabilización de las Ru NPs. Por último, se ha evaluado la actividad catalítica de estas Ru NPs en la hidrogenación de multitud de sustratos aromáticos, observándose diferencias significativas en función del ligando estabilizador utilizado. En el Capítulo 5 se ha investigado la formación de MNPs a través de la aproximación organometálica utilizando el óxido de grafeno reducido dopado con átomos de nitrógeno (NH2-rGO) como soporte. En la primera parte del capítulo, sintetizamos Ru NPs soportadas sobre NH2-rGO (Ru@NH2-rGO) y rGO (Ru@rGO), con la intención de investigar el rol de los átomos de N en la estabilización de las MNPs, así como en su actividad catalítica. Para ello, se estudió la hidrogenación del ácido palmítico a 1-hexadecanol, siendo el Ru@NH2-rGO el catalizador heterogéneo monometálico de Ru más activo y selectivo reportado hasta la fecha (99% conversión y 93 % selectivo). En la segunda parte del capítulo, generamos PtRu NPs con distintas composiciones atómicas (5:1, 1:1 y 1:5) sobre NH2-rGO, siguiendo la aproximación organometálica. La misma velocidad de descomposición de los precursores Pt(NBE)3 y Ru(COD)(COT) nos permitió generar las NPs de tipo aleación. Estos sistemas bimetálicos (PtxRuy@NH2-rGO) se estudiaron en la hidrogenación de multitud de compuestos con grupos polares (C=O), observándose diferencias significativas en función del soporte utilizado y la composición atómica de las MNPs. Por último, en el Capítulo 6 se investigó el uso de nanopartículas magnéticas (MagNPs) para emitir calor por pérdidas de histéresis en presencia de un campo magnético oscilante de alta frecuencia. En primer lugar, se generaron nuevos agentes calefactores basados en MagNPs bimetálicas de tipo "core-shell" de CoNi encapsuladas en carbono (Co@Ni@C), con el objetivo de hidrogenar selectivamente el CO2 a CO (RWGS) obteniéndose excelentes resultados catalíticos. Por último, también presentamos la síntesis de una nueva MagNP de tipo "core-shell" (FeCo@Ni) para su aplicación en catálisis inducida magnéticamente en disolución, siendo capaz de modular su selectividad al producto de la hidrogenación o de la hidrodesoxigenación del HMF en función del campo magnético aplicado. Además, después de su encapsulación en carbono (FeCo@Ni@C) han demostrado ser activas, selectivas y estables en la reducción de multitud de sustratos oxigenados derivados de la biomasa en medio acuoso, siendo el primer ejemplo reportado hasta la fecha de catálisis magnética realizada en agua. / [CAT] La present Tesi Doctoral es desenvolupa en l'àmbit de la catàlisi, la qual està emmarcada dins del concepte de Química Sostenible. Concretament, la investigació s'ha centrat en el desenvolupament i aplicació de nous catalitzadors basats en nanopartícules metàl·liques col·loïdals i suportades per dur a terme reaccions d'interès. Totes les MNPs sintetitzades en aquesta tesi doctoral es van dur a terme a partir de l'aproximació organometàl·lica, on generalment es descompon un precursor organometàl·lic sota condicions suaus de reacció i en presència d'un agent estabilitzador (molècula orgànica o suport). En el Capítol 4 de la Tesi, s'ha descrit el primer exemple d'estabilització de Ru NPs amb una nova família de lligands policíclics aromàtics no plans, denominats nanografens (hept-HBC). Específicament, s'han utilitzat dos tipus diferents de nanografen distorsionat: i) un funcionalitzat amb un grup carbonil, i un altre ii) funcionalitzat amb un grup metilè en la mateixa posició (Ru@1 i Ru@2, respectivament). Gràcies a la similitud amb els sistemes basats en MNPs suportades en grafè o derivats, aquest material pot utilitzar-se com a referència per a estudiar els modes de coordinació i dinàmiques d'aquests amb la superfície de la nanopartícula. A partir d'un estudi combinat teòric/experimental s'ha demostrat que la curvatura dels nanografens hept-HBC és crucial per a l'estabilització de les Ru NPs. Finalment, s'ha avaluat l'activitat catalítica d'aquestes Ru NPs en la hidrogenació de multitud de substrats aromàtics, observant diferències significatives en funció del lligand estabilitzador utilitzat. En el Capítol 5 s'ha investigat la formació de MNPs a través de l'aproximació organometàl·lica utilitzant l'òxid de grafè reduït dopat amb àtoms de nitrogen (NH2-rGO) com a suport. En la primera part del capítol, vam sintetitzar Ru NPs suportades sobre NH2-rGO (Ru@NH2-rGO) i rGO (Ru@rGO), amb l'intenció d'investigar el paper dels àtoms de N en l'estabilització de les MNPs, així com en la seua activitat catalítica. Per a això, es va estudiar la hidrogenació de l'àcid palmític a 1-hexadecanol, sent el Ru@NH2-rGO el catalitzador heterogeni monometàl·lic de Ru més actiu i selectiu reportat fins a la data (99% conversió i 93 % selectiu). En la segona part del capítol, es van generar PtRu NPs amb diferents composicions atòmiques (5:1, 1:1 i 1:5) sobre NH2-rGO, seguint l'aproximació organometàl·lica. La mateixa velocitat de descomposició dels precursores Pt(NBE)3 i Ru(COD)(COT) ens va permetre generar les NPs de tipus aliatge. Aquests sistemes bimetàl·lics (PtxRuy@NH2-rGO) es van estudiar en la hidrogenació de multitud de compostos amb grups polars (C=O), observant-se diferències significatives en funció del suport utilitzat i la composició atòmica de les MNPs. Finalment, en el Capítol 6 es va investigar l'ús de nanopartícules magnètiques (MagNPs) per emetre calor per pèrdues d'histèresi en presència d'un camp magnètic oscil·lant d'alta freqüència. En primer lloc, es van generar nous agents calefactores basats en generar MagNPs bimetàl·liques de tipus "core-shell" de CoNi encapsulades en carbó (Co@Ni@C), amb l'objectiu d'hidrogenar selectivament el CO2 a CO (RWGS) obtenint excel·lents resultats catalítics. Finalment, també presentem la síntesi d'una nova MagNP de tipus "core-shell" (FeCo@Ni) per a la seva aplicació en catàlisi induïda magnèticament en solució, demostrant ser capaç de modular la seva selectivitat al producte de l'hidrogenació o de l'hidrodesoxigenació del HMF en funció del camp magnètic aplicat. A més, després de la seva encapsulació en carbó (FeCo@Ni@C) han demostrat ser actives, selectives i estables en la reducció de multitud de substrats oxigenats derivats de la biomassa en medi aquós, sent el primer exemple reportat fins a la data de catàlisi magnètica realitzada en aigua. / [EN] This Doctoral Thesis is developed in the field of catalysis, which is framed within the concept of Sustainable Chemistry. Specifically, the research has focused on the development and application of new catalysts based on colloidal and supported metallic nanoparticles to carry out relevant catalytic reactions. All the MNPs synthesized in this doctoral thesis were carried out from the organometallic approach, where an organometallic precursor is generally decomposed under mild conditions, room temperature and 3 bar H2, in the presence of a stabilizing agent (organic molecule, polymer, or support). The catalytic properties of MNPs are greatly influenced by the stabilizing agents used, which are capable of modifying their electronic and steric properties. Therefore, the search for new ligands capable of modulating these properties is of great scientific interest. In Chapter 4 of the Thesis, we describe the first example of Ru NPs stabilized with a new family of non-planar polycyclic aromatic ligands, called nanographenes (hept-HBC). Specifically, two different types of distorted nanographene have been used: i) one functionalized with a carbonyl group, and another ii) functionalized with a methylene group in the same position (Ru@1 and Ru@2, respectively). Thanks to the resemblance with systems based on supported-MNPs on graphene or derivatives, this material can be used as a reference to study the coordination modes and dynamics of these with the surface of the nanoparticle. A combined theoretical/experimental study revealed that the curvature of hept-HBC nanographenes is crucial for the stabilization of Ru NPs. Finally, the catalytic activity of these Ru NPs has been evaluated in the hydrogenation of multitude of arenes, observing significant differences depending on the stabilizing ligand used. In Chapter 5, the formation of MNPs through the organometallic approach was investigated using reduced graphene oxide N-doped (NH2-rGO) as support. In the first part of the chapter, Ru NPs supported on NH2-rGO (Ru@NH2-rGO) and rGO (Ru@rGO) were synthesized, with the aim of investigating the role of N atoms in the stabilization of the MNPs, as well as their catalytic activity. For this purpose, the hydrogenation of palmitic acid to 1-hexadecanol was studied, and Ru@NH2-rGO was found to be the most active and selective monometallic Ru-based heterogeneous catalyst reported to date (99% conversion and 93% selectivity). In the second part of the chapter, PtRu NPs with different atomic compositions (5:1, 1:1, and 1:5) were generated on NH2-rGO using the organometallic approach. The same decomposition rate of Pt(NBE)3 and Ru(COD)(COT) precursors allowed us to generate alloy-type NPs. These bimetallic systems (PtxRuy@NH2-rGO) were studied in the hydrogenation of a variety of compounds with polar groups (C=O), and significant differences were observed depending on the support used and the atomic composition of the MNPs. Finally, in Chapter 6 the use of magnetic nanoparticles (MagNPs) for heat generation through hysteresis losses in the presence of a high-frequency oscillating magnetic field was investigated. Firstly, new heat-generating agents based on bimetallic core-shell type CoNi MagNPs encapsulated in carbon (Co@Ni@C) were synthesized with the aim of selectively hydrogenate CO2 to CO (RWGS), obtaining excellent catalytic results. Finally, a new core-shell type MagNP (FeCo@Ni@C), the MagNPs proved to be active, selective, and stable in the reduction of several oxygenated substrates derived from biomass in aqueous media, being the first reported example of magnetic catalysis performed in water to date. In Chapter 6, the crucial role of MagNP encapsulation was demonstrated, where carbon not only limits the total oxidation of MagNPs but also prevents their sintering at high temperatures (~ 700 °C) in gas phase and avoids their aggregation in liquid phase. / Cerezo Navarrete, C. (2023). Aplicación catalítica de nuevos nanosistemas obtenidos a partir de la aproximación organometálica [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196366