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Clústeres y átomos aislados de platino como catalizadores para reacciones químicas de interés industrialRivero Crespo, Miguel Ángel 30 October 2018 (has links)
En la presente tesis doctoral se ha llevado a cabo un estudio de los clústeres y átomos aislados de platino como catalizadores para reacciones químicas de interés en la química industrial.
En la reacción de hidrosililación de alquinos se ha demostrado que la selectividad está determinada por las especies activas de platino. Para el caso de la hidrosililación anti-Markovnikov, la más habitual, los verdaderos catalizadores son átomos aislados de platino, mientras que para la hidrosililación Markovnikov, son los clústeres de platino triatómico los responsables de la selectividad observada. Se han sintetizado un elevado número de compuestos ¿-alquenilsilanos y se ha demostrado su versatilidad como intermedios de síntesis. Además, el mecanismo de la reacción parece apuntar a la agregación de átomos de platino con moléculas de silano como parámetro clave para la selectividad de la reacción.
Se pueden emplear clústeres de Pd y Pt de <10 átomos formados in situ o preformados como catalizadores para reacciones de acoplamiento cruzado (Heck, Suzuki o Sonogashira) en función de la base empleada, con elevada actividad y selectividad. Esto se debe a una mayor facilidad en la adición oxidativa, lo que permite que la reacción esté controlada por la base.
Por otro lado se han empleado materiales híbridos clúster-MOF o SAC-MOF como catalizadores heterogéneos para reacciones de interés industrial. En primer lugar clústeres de Pt02 estabilizados dentro de un MOF se han empleado como catalizadores para las reacciones de formación de NH4CN, la metanación de CO2 y la hidrogenación de olefinas. También se han empleado átomos de platino con bajo estado de oxidación y estabilizadas por ligandos duros (H2O) sin retrodonación en un MOF como catalizadores para la reacción de desplazamiento de gas de agua (WGS). / In this thesis, a study of platinum clusters and single atoms as catalysts for industrially relevant chemical reactions have been carried out.
Selectivity in alkyne hydrosilylation is determined by platinum active species. For anti-Markovnikov hydrosilylation, the thermodynamic product, the true catalysts are isolated platinum atoms, while for Markovnikov hydrosilylation, three atom platinum clusters are responsible for the observed selectivity. A big number of ¿-alkenylsilanes have been synthesized and their versatility as synthetic intermediates demonstrated. Reaction mechanism points to platinum-silane aggregation as key factor for reaction selectivity.
Pd and Pt clusters with <10 atoms either formed in-situ or preformed can be used as catalysts for cross-coupling reactions (Heck, Suzuki and Sonogashira) depending on the base, with high activity and selectivity. This is due to an easier oxidative addition, which allows the base to control reaction.
Hybrid materials cluster/SAC-MOF have been used as heterogeneous catalysts for industrially relevant reactions. First, Pt02 clusters stabilized inside a MOF catalyze NH4CN formation, CO2 methanation and olefin hydrogenation. Low valent Pt atoms stabilized by hard ligands (H2O) without retrodonation have proved to catalyze very efficiently the low-temperature water gas shift reaction. / En la present tesi doctoral s'ha dut a terme un estudi dels clústers i àtoms aïllats de platí com a catalitzadors per reaccions químiques d'interès en la química industrial.
En la reacció d'hidrosililació d'alquins s'ha demostrat que la selectivitat està determinada per les espècies actives de platí. Per al cas de la hidrosililació anti-Markovnikov, la més habitual, els vertaders catalitzadors són àtoms aïllats de platí, mentre que per la hidrosililació Markovnikov, són els clústers de platí triatòmic els responsables de la selectivitat observada. S'han sintetitzat un elevat nombre de compostos ¿-alquenilsilans i s'ha demostrat la seua versatilitat com intermedis de síntesi. A més, el mecanisme de la reacció pareix apuntar a la agregació d'àtoms de platí amb molècules de silà com a paràmetre clau per a la selectivitat de la reacció.
Es poden emprar clústers de pal·ladi i platí de <10 àtoms formats in situ o preformats com catalitzadors per reaccions d'acoblament creuat (Heck, Suzuki o Sonogashira) en funció de la base emprada, amb elevada activitat i selectivitat. Això es deu a una major facilitat en la adició oxidativa, el que permet que la reacció estigui controlada per la base.
Per altra banda s'han emprat materials híbrids clúster-MOF o SAC-MOF com catalitzadors heterogenis per reaccions d'interès industrial. En primer lloc clústers de Pt02 estabilitzats dins d'un MOF s'han emprat com catalitzadors per les reaccions de formació de NH4CN, la metanació de CO2 i la hidrogenació d'etilè. També s'han emprat àtoms de platí amb baix estat d'oxidació i estabilitzats per lligands durs (H2O) sense retrodonació en un MOF com a catalitzadors per la reacció de desplaçament de gas de agua (WGS). / Rivero Crespo, MÁ. (2018). Clústeres y átomos aislados de platino como catalizadores para reacciones químicas de interés industrial [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/111827 / TESIS
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Catalizadores sólidos como alternativa a compuestos de hierro en disolución para reacciones orgánicas de interés industrialTejeda Serrano, María 02 September 2019 (has links)
[ES] En la presente tesis doctoral se ha llevado a cabo la búsqueda de catalizadores heterogéneos para sustituir catalizadores homogéneos de Fe en reacciones químicas de interés industrial y/o sintético.
En primer lugar, se sintetizaron nanopartículas planas de FeOx en la superficie de diferentes óxidos inorgánicos ácidos mediante un proceso redox en one-pot a temperatura ambiente, las cuales catalizan la semi-hidrogenación de alquinos con altos rendimientos y selectividad. Esta reacción había sido descrita con complejos de Fe en disolución. Estos óxidos mixtos de Fe2,3+ son capaces de disociar y transferir H2 a alquinos de forma quimio- y estereoselectiva asistidos por los grupos hidroxilo del soporte del óxido inorgánico, el cual, por tanto, está involucrado en el mecanismo de la reacción. Este mecanismo se asemeja al que usan las enzimas de Fe hidrogenasas en la naturaleza para disociar H2.
Además, sitios aislados de FeIII-O en sólidos catalizan de manera quimioselectiva la hidrogenación del acetileno en corrientes de etileno, en condiciones industriales front-end. Para corroborar la naturaleza del centro activo, se preparó un MOF con sitios de FeIII accesibles dentro de sus poros, mediante la funcionalización post-sintética por metátesis de catión en los cristales, lo que permitió resolver la estructura del sólido por difracción de rayos X de monocristal, confirmando que el centro catalítico es FeIII-O.
Por otra parte, se llevó a cabo la reacción radicalaria ATRA entre alquenos y halogenuros de carbono con complejos de Fe de baja valencia y también con fosforeno, un material bidimensional de fósforo análogo al grafeno. Los compuestos de Fe en disolución y el fosforeno tienen en común que son ricos en electrones disponibles para iniciar la reacción radicalaria, por lo que presentan una actividad mucho mayor que sus compuestos análogos en estados de oxidación más altos, incluso a temperatura ambiente.
Y por último, se llevó a cabo la metátesis de carbonilo-olefina intermolecular entre aldehídos aromáticos y éteres vinílicos catalizada por ácidos de Brönsted o Lewis convencionales (como sales de Fe) en disolución, y también con ácidos sólidos en un reactor de lecho fijo en flujo, particularmente con el aluminosilicato montmorillonita K-10, que mostró una extraordinaria actividad catalítica debido a su capacidad para estabilizar los carbocationes intermedios formados durante la reacción. / [CAT] En la present tesi doctoral s'ha dut a terme la recerca de catalitzador heterogenis per a substituir catalitzadors homogenis de Fe en reaccions químiques d'interès industrial i/o sintètic.
En primer lloc, es sintetitzaren nanopartícules planes de FeOx en la superfície de diferents òxids inorgànics àcids mitjançant un procés redox en one-pot a temperatura ambient, les quals catalitzen la semi-hidrogenació d'alquins amb alts rendiments i selectivitat. Aquesta reacció havia sigut descrita amb complexes de Fe en dissolució. Aquests òxids mixtes de Fe2,3+ són capaços de dissociar i transferir H2 a alquins de forma quimio- i estereoselectiva assistits pels grups hidroxil del suport de l'òxid inorgànic, el qual, per tant, està involucrat en el mecanisme de la reacció. Aquest mecanisme s'assembla al que utilitzen les enzimes de Fe hidrogenases en la natura para dissociar H2.
A més a més, llocs aïllats de FeIII-O en sòlids catalitzen de manera quimioselectiva la hidrogenació del acetilè en corrents de etilè, en condicions industrials front-end. Per a corroborar la natura del centre actiu, es va preparar un MOF amb llocs de FeIII accessibles dins dels seus porus, mitjançant la funcionalització post-sintètica per metàtesis de catió en els cristalls, el que va permetre resoldre l'estructura del sòlid per difracció de rajos X de monocristall, confirmant que el centre catalític és FeIII-O.
Per altra banda, es va dur a terme la reacció radicalaria ATRA entre alquens i halogenurs de carboni amb complexos de Fe de baixa valència i també amb fosforè, un material bidimensional de fòsfor anàleg al grafè. Els compostos de Fe en disolució i el fosforè tenen en comú que són rics en electrons disponibles per a iniciar la reacció radicalaria, per el qual presenten una activitat molt major que els seus compostos anàlogues en estats d'oxidació més alts, inclòs a temperatura ambient.
I per últim, es va realitzar la metàtesis de carbonil-olefina intermolecular entre aldehids aromàtics i èters vinílics catalitzada per àcids de Brönsted o Lewis convencionals (com sals de Fe) en dissolució, i també amb àcids sòlids en un reactor de llit fixe en flux, particularment amb el aluminosilicat montmorillonita K-10, que mostrà una extraordinària activitat catalítica deguda a la seua capacitat per a estabilitzar els carbocations intermedis formats durant la reacció. / [EN] In the present doctoral thesis, the search of heterogeneous catalysts to substitute homogeneous Fe catalysts in chemical reactions of industrial and/or synthetic interest has been carried out.
First, planar FeOx nanoparticles were synthesized on the surface of different acidic inorganic oxides using a one-pot redox process at room temperature, which catalyze the semi-hydrogenation of alkynes with high yields and selectivity. This reaction had been described previously only with Fe complexes in solution. These mixed Fe2,3+ oxides are capable to dissociate and transfer H2 to alkynes in chemo- and stereoselective manner assisted by the hydroxyl groups of the inorganic oxide support, which, as a result, is involved in the mechanism of the reaction. This mechanism resembles that used by the Fe hydrogenases enzymes in nature to dissociate H2.
In addition, FeIII-O isolated sites in solids catalyze chemo- and stereoselectively the hydrogenation of acetylene in ethylene streams under front-end industrial conditions. To corroborate the nature of the active center, a MOF with accessible FeIII sites within its pores was prepared by post-synthetic metathesis of cations in crystals, which allowed resolving the structure of the solid by single crystal X-ray diffraction, confirming that the catalytic center is FeIII-O.
On the other hand, the ATRA radical reaction between alkenes and carbon halides was carried out with low-valent Fe complexes and also with phosphorene, a phosphorous based two-dimensional material analogous to graphene. The compounds of Fe in solution and phosphorene have in common that they are rich in electrons available to initiate the radical reaction, so they have a much higher activity than their analogs in higher oxidation states and are active even at room temperature.
Finally, the intermolecular carbonyl-olefin metathesis between aromatic aldehydes and vinyl ethers was carried out catalyzed by conventional Brönsted or Lewis acids in batch (including Fe salts), and also in a fixed-bed reactor in flow using solid acids, particularly with the aluminosilicate montmorillonite K-10, which showed an extraordinary catalytic activity due to its ability to stabilize the carbocation intermediate formed during the reaction. / Tejeda Serrano, M. (2019). Catalizadores sólidos como alternativa a compuestos de hierro en disolución para reacciones orgánicas de interés industrial [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124966 / TESIS
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Reticular Chemistry for the Highly Connected Porous Crystalline Frameworks and Their Potential ApplicationsChen, Zhijie 31 March 2018 (has links)
Control at the molecular level over porous solid-state materials is of prime importance for fine-tuning the local structures, as well as the resultant properties. Traditional porous solid-state materials such as zeolite and activated carbon are the benchmarks in the current market with vital applications in sorption and heterogeneous catalysis. However, the adjustments of pore size and geometry of those materials, which are essential for the broader aspect of modern prominent applications, remain challenging. Reticular chemistry has emerged as a dominant tool toward the ‘designed syntheses’ of porous crystalline frameworks (e.g. metal-organic frameworks (MOFs)) with a specific pore system.
This dissertation illustrates the power of reticular chemistry and its use in the directional assembly of highly coordinated MOF materials, as well as their potential applications such as gas storage, natural gas upgrading, and light hydrocarbon separation. Highly connected minimal edge-transitive derived and related nets, obtained via the deconstruction of nodes of the edge-transitive nets, are suitable blueprints and can potentially be deployed in the future ‘designed syntheses’ of MOFs. The further employment of the conceptual net-coded building units (e.g. highly connected MBBs
and edge-transitive SBLs) in the practical reticular synthesis results in the rational design and construction of functional MOF platforms like shp-, alb-, kce-, kex- and eea- MOFs.
In addition, the isoreticular synthesis of Al-cea-MOF-2 with functionalized pendant acid moieties inside pore channels in comparison to the parent Al-cea-MOF-1 led to enhanced light hydrocarbons separation performance. Moreover, controlling the molecular defects in Zr-fum-fcu-MOFs resulted in the development of an ultramicroporous adsorbent with an engineered aperture size for the highly efficient separation of butane/iso-butane.
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Synthesis of ZIF-8 membrane via facile cathodic deposition in aqueous medium for propylene/propane separationChi, Heng-Yu 12 1900 (has links)
Metal-organic frameworks (MOFs) are porous crystalline materials built by metal clusters
coordinated to organic ligands. Synthesis of MOFs has attracted considerable attention in recent decades, owing to its potential for a wide range of applications such as gas
separation, dye adsorption, and catalysis, etc. The development of MOF membranes
further enhances the potential of this type of material in industrial applications.
Membrane fabrication methods, including in-situ growth, seeded secondary growth,
interfacial growth, and vapor-phase deposition, have been widely studied. However, most of these methods either require a complicated synthesis procedure or are timeconsuming.
Recently, the electrochemical synthesis has emerged as a highly promising approach to fabricate MOF membranes in a scalable manner, because it allows shorter synthesis time, milder synthesis condition, continuous reaction, and crystal self-healing.
In this thesis, for the first time, an aqueously cathodic deposition (ACD) approach was developed to fabricate ZIF-8 type of MOF membranes without the addition of any
supporting electrolyte or modulator. The fabrication process used 100% water as the sole solvent, and a low-defect density membrane was obtained in only 60 min under room temperature without any pre-synthesis treatment. The membrane exhibited superior performance in C3H6/C3H8 separation with C3H6 permeance of 182 GPU and selectivity of 142, making it sit at the upper bound of permeance versus selectivity graph, outperforming the majority of the published data up to 2019. Notably, this approach used an extremely low current density (0.13 mA cm-2) operated under a facile apparatus setup, enabling an attractive method for environmentally friendly, energy-efficient, and scalable MOF membrane fabrications. This work demonstrates the enormous potential of aqueously electrochemical deposition of the MOF membrane in future research.
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DESARROLLO DE NUEVOS MATERIALES NANOESTRUCTURADOS BASADOS EN REDES ORGANOMETÁLICAS CON APLICACIONES BIOMÉDICASCabrera García, Alejandro 01 April 2019 (has links)
[ES] El desarrollo de nuevas metodologías para la detección y tratamiento del cáncer pasa por la necesidad de minimizar los efectos secundarios de las terapias actuales. En este campo, la nanotecnología permite diseñar y fabricar vehículos de agentes terapéuticos y/o de diagnóstico que pueden dirigirse selectivamente al tejido patológico y responder a estímulos específicos que permiten ejercer un control estricto sobre la actividad biológica de estos sistemas.
En este contexto, en la presente tesis doctoral se aborda el diseño, síntesis y validación biológica de sistemas basados en nanopartículas de redes organometálicas (nanoMOFs). El objetivo general es el estudio y evaluación del potencial de los nanoMOFs como componentes estructurales de vehículos destinados a aplicaciones biomédicas, concretamente a la difusión intracelular de fármacos y a la mejora de la resolución de imagen clínica. Dicho planteamiento da lugar a dos retos principales:
Desarrollar sistemas estables basados en nanoMOFs de Fe3+ para la difusión intracelular de fármacos antitumorales.
Desarrollar sistemas estables basados en nanoMOFs de Fe3+ y Gd3+ para la obtención de nuevos agentes de contraste para mejorar la imagen por resonancia magnética.
Para implementar el primero de estos retos, se han preparado materiales para liberación controlada de camptotecina (CPT) basados en nanoMOFs funcionalizados con grupos amino, MIL-100(Fe) y MIL-101(Fe) nanoMOF a los cuales se une CPT mediante enlace covalente sobre los grupos amino, ya sea por amidación o por química click. Los derivados del MIL-101(Fe) cargados con CPT presentan una internalización celular mejorada debido a su potencial ¿ positivo y una fuerte respuesta al pH ácido, aumentando la descarga del fármaco de 2 a 4 veces a pH 5, lo que estimula la liberación intracelular por actividad endosomolítica. En general, estos nanoMOFs constituyen un vehículo apropiado para la difusión segura de CPT, con gran potencial para su uso in vivo.
Respecto del segundo reto, se han desarrollado diversos agentes de contraste para imagen por resonancia magnética basados en un MOF análogo del azul de Prusia, Gd(H2O)4[Fe(CN)6], capaces de mejorar tanto la relajatividad longitudinal (T1), como la transversal (T2). Mediante reacción del Gd(H2O)4[Fe(CN)6] con silicato en medio alcalino se han obtenido nanopartículas monodispersas de óxido de Gd-Si conservando la morfología original, con valores de T1 y T2 in vitro superiores a las disoluciones comerciales de quelatos de Gd3+ y excelente estabilidad en fluidos fisiológicos. Asimismo, se ha obtenido un nuevo material híbrido por recubrimiento de las nanopartículas de Gd(H2O)4[Fe(CN)6] con una delgada capa de sílice, por hidrólisis y polimerización del silicato a pH neutro. Dicho material presenta valores de T1 un orden de magnitud superior a los sistemas basados en quelatos de Gd3+ y un contraste positivo mucho más fuerte en imágenes de resonancia in vitro e in vivo, debido al efecto sinérgico entre los centros magnéticos de Gd3+ y Fe3+ estrechamente conectados a través de enlaces tipo ciano en una estructura cristalina muy compacta. Además, estas nanopartículas presentan una composición muy homogénea y una relación atómica de Gd:Fe constante, proporcionando excelente reproducibilidad en la señal. / [CA] El desenvolupament de noves metodologies per a la detecció i tractament del càncer passa per la necessitat de minimitzar els efectes secundaris de les teràpies actuals. En aquest camp, la nanotecnologia permet dissenyar i fabricar vehicles d'agents terapèutics i/o de diagnòstic que poden dirigir-se selectivament al teixit patològic i respondre a estímuls específics que permeten exercir un control estricte sobre l'activitat biològica d'aquests sistemes.
En aquest context, en la present tesi doctoral s'aborda el disseny, síntesi i validació biològica de sistemes basats en nanopartícules de xarxes organometàliques (nanoMOFs). L'objectiu general és l'estudi i avaluació del potencial dels nanoMOFs, com a components estructurals de vehicles destinats a aplicacions biomèdiques, concretament a la difusió intracel·lular de fàrmacs i a la millora de la resolució d'imatge clínica. Aquest plantejament dona lloc a dos reptes principals:
Desenvolupar sistemes estables basats en nanoMOFs de Fe3+ per a la difusió intracel·lular de fàrmacs antitumorals.
Desenvolupar sistemes estables basats en nanoMOFs de Fe3+ i Gd3+ per a l'obtenció de nous agents de contrast per a millorar la imatge per ressonància magnètica.
Per a implementar el primer d'aquests reptes, s'han preparat sistemes d'alliberament controlat de camptotecina (CPT) basats en nanoMOFs funcionalitzats amb grups amino, MIL-100(Fe) i MIL-101(Fe) nanoMOF als quals s'uneix CPT mitjançant enllaç covalent sobre els grups amino, ja siga per amidació o per química click. Els derivats del MIL-101(Fe) carregats amb CPT presenten una internalització cel·lular millorada a causa del seu potencial ¿ positiu i una forta resposta al pH àcid, augmentant la descàrrega del fàrmac de 2 a 4 vegades a pH 5, la qual cosa estimula l'alliberament intracel·lular per activitat endosomolítica. En general, aquests nanoMOFs constitueixen un vehicle apropiat per a la difusió segura de CPT, amb gran potencial per al seu ús in vivo.
Respecte del segon repte, s'han desenvolupat diversos agents de contrast per a ressonància magnètica basats en un MOF anàleg del blau de Prússia, Gd(H2O)4[Fe(CN)6], capaços de millorar tant la relaxativitat longitudinal (T1), com la transversal (T2). Mitjançant reacció del Gd(H2O)4[Fe(CN)6] amb silicat en pH alcalí s'ha obtingut nanopartícules monodisperses d'òxid de Gd-Si conservant la morfologia original, amb valors de T1 i T2 in vitro superiors a les dissolucions comercials de quelats de Gd3+ i excel·lent estabilitat en fluids fisiològics. Així mateix, s'ha obtingut un nou material híbrid per recobriment de nanopartícules de Gd(H2O)4[Fe(CN)6] amb una capa prima de sílice, per hidròlisi i polimerització del silicat a pH neutre. Aquest material presenta valors de T1 un ordre de magnitud superior als sistemes basats en Gd3+ i un contrast positiu molt més fort en imatges de ressonància in vitro e in vivo, a causa d'aquest efecte sinèrgic existent entre els centres magnètics de Gd3+ i Fe3+ estretament connectats a través d'enllaços tipus ciano en una estructura cristal·lina molt compacta. A més, aquestes nanopartícules presenten una composició molt homogènia i una relació atòmica de Gd:Fe constant, proporcionant total reproductibilitat en el senyal. / [EN] Developing new methodologies for cancer diagnosis and therapy involves the need to minimize current therapies secondary effects. In this field, nanotechnology brings out the opportunity to design and manufacture vehicles for therapeutic and/or diagnostic agents, which may be selectively targeted to the pathological tissue and respond under specific stimuli that allow to accurately control the systems biological activity.
In this context, this doctoral thesis tackles the design, synthesis and biological validation of metalorganic nanoparticle-based systems (nanoMOFs). The general aim is the study and evaluation of nanoMOFs potential as structural components of vehicles for biomedical use, mostly to drug intracellular diffusion and clinical imaging improvement. This rationale leads to two main challenges:
Developing stable systems based on Fe3+ nanoMOFs for intracellular diffusion of antitumor drugs.
Developing stable systems based on Fe3+ and Gd3+ nanoMOFs to obtain novel contrast agents that can enhance magnetic resonance imaging.
In order to address the first challenge, we have prepared camptothecin (CPT) controlled release materials based on amino group functionalized nanoMOFs, MIL-100(Fe) and MIL-101(Fe), where CPT is covalently bonded over amino groups by amidation or click chemistry. CPT-loaded MIL-101(Fe) derivatives have shown improved cell internalization due to their positive ¿ potential and a strong response to acid pH, increasing drug discharge over 2-4 fold at pH 5, which promotes intracellular release by endosomolytic activity. Overall, these nanoMOFs provide an appropriate vehicle for safe CPT diffusion, with good potential at in vivo use.
With regards to our second challenge, we have developed different contrast agents for magnetic resonance imaging based on a Prussian Blue analogue, Gd(H2O)4[Fe(CN)6], that is able to increase both longitudinal (T1) and transversal relaxivity (T2). By reaction of Gd(H2O)4[Fe(CN)6] with silicate in alkaline medium we have obtained Gd-Si oxide monodispersed nanoparticles keeping the pristine morphology, with T1 y T2 in vitro values higher that Gd3+ chelate commercial solutions. Moreover, we have obtained a novel hybrid material by Gd(H2O)4[Fe(CN)6] nanoparticle covering with a thin silica layer, by silicate hydrolysis and polymerization at neutral pH. Such material presented T1 values one order higher that Gd3+ chelate based systems and a positive contrast much stronger in magnetic resonance images in vitro and in vivo, due to the synergetic effect between Fe3+ and Gd3+ magnetic centers closely connected through cyano-bridge bonds in an extremely dense structure. Furthermore, these nanoparticles present a very homogeneous composition and a constant Gd:Fe atomic ratio, providing excellent signal reproducibility. / En primer lugar, me gustaría dar las gracias a mi director de
tesis, quien confió en mí para el desarrollo del proyecto que se
plasma en estas páginas y a la fundación La Caixa, por el
soporte económico que he recibido en esta etapa académica. / Cabrera García, A. (2019). DESARROLLO DE NUEVOS MATERIALES NANOESTRUCTURADOS BASADOS EN REDES ORGANOMETÁLICAS CON APLICACIONES BIOMÉDICAS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/118799 / TESIS
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Studies on Highly Ion-conductive Metal-Organic Frameworks by Postsynthetic Modification Methods / 合成後修飾法を用いた高イオン伝導性金属-有機構造体の開発に関する研究Sarango Ramírez, Marvin Kevin 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23458号 / 理博第4752号 / 新制||理||1681(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 吉村 一良, 教授 竹腰 清乃理 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
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Polynuclear Rare-earth (RE) based Metal-Organic Frameworks (MOFs): From Topological Exploration to Preparation of Tailor-made MOFsAssen, Ayalew H. 09 1900 (has links)
Metal-organic frameworks (MOFs) have emerged as a unique class of solid-state materials, exemplifying the power of combining organic and inorganic chemistries to address the enduring challenge pertaining to designing solid state materials with desired attributes. Notably, a myriad of MOFs were constructed in the last two decades. In particular, the use of well-defined polyatomic clusters as molecular building blocks (MBBs) permitted access to the looked-for geometrical features, incorporated in preselected building units prior to the assembly process, guiding the assembly of a targeted network. Nevertheless, the diverse coordination modes and geometries of rareearth (RE) elements requires the introduction of a sophisticated controlled approach for their use as polynuclear cluster MBBs. Subsequently, our group has introduced the use of 2-fluorobenzoic acid (2-FBA) modulator that consistently allows the in situ control and formation of multi-nuclear RE MBBs. The presented work in this thesis demonstrates the use of elaborate RE MBBs and their successful deployment in reticular chemistry for the construction of particular MOF platforms expressing unique properties in term of gas separations. Accordingly, the RE hexanuclear clusters were used to construct fcu- and fluMOF platforms with controlled pore-aperture sizes. Markedly, the isolated RE-MOFs, REfum-fcu-MOF and RE-bqdc-flu-MOF, showed unprecedented paraffin/isoparaffin molecular sieving.
Further tuning of the windows of RE-fcu-MOFs afforded the assembly of a MOF suitable for propylene/propane separation. The exceptional thermal and chemical stability and high adsorption selectivity of some of these MOFs prompted us to explore the fcu-MOF platform for selective removal of H2S/CO2 from CH4 and for sensing of toxic gases, namely H2S and NH3.
Additionally, the research presented in this dissertation highlights the topological exploration for the formation of new MOFs: i) highly-connected polyatomic RE-MOFs in combination with tetrahedrally oriented tetracarboxylate ligands afforded the formation MOFs with new underlying topologies, namely kna-, kel- and kem-MOFs; ii) mixed-metal approach (RE plus other elements) was employed to fabricate MOFs containing in situ formed metalo-linker MBBs that are difficult to be pre-assembled by organic synthesis; iii) supermolecular building layer (SBL) approach was extended from the prevalent sql to the less explored double sql layer for the rational design of pillared MOFs.
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MAGNETISM IN A NUMBER OF METAL ORGANIC FRAMEWORKS (MOFs) WITH 1D AND 3D CHARACTERISTICS: AN EXPERIMENTAL AND ANALYTICAL STUDYHamida, Youcef January 2012 (has links)
Metal Organic Frameworks (MOFs) exhibit many excellent physical properties including magnetic properties for potential applications in devices. More importantly for the subject of this thesis, MOFs are ideal for the realization of low dimensional magnetism because of the large selection of ligands connecting magnetic centers in making the framework. The materials studied in this thesis include ten magnetic MOFs of the form M(L1)(L2) [M = Cu, Ni, Co, Fe, Mn; L1 = NDC, bpdc, BDC, BODC, N3; L2 = DMF, H2O, TED, bpy]. Polycrystalline powder samples as well as single crystal samples were synthesized. Their crystal structures were determined, and their magnetic and thermodynamic properties were measured and analyzed. Eight of these materials were characterized as 1D magnets and two as 3D magnets. In the 1D case it is found that above Tm [the temperature at which the magnetic susceptibility χ(T) has a peak] the magnetic behavior of MOFs (S ≥ 1) can be well described with the Classical Fisher Model (CFM). Near and below TC the spins take a more definite orientation than allowed for in the CFM and hence the Ising Model (IM) was used for fitting. Both CFM and IM yield fairly consistent intrachain couplings (J) when applied in their appropriate temperature region. To estimate the interchain exchange (J′), the susceptibility for a magnetic chain in the mean field of neighboring chains is used. In all cases, as expected, the ratio of J to J′ was less than 10%. The special case of Cu(N3)2bpy (S = ½) was analyzed with the spin ½ IM. Although the specific heat data (Ctotal) for most of the 1D MOFs showed no clear phase transition, a low temperature fit to the electron-phonon specific heats yielded apparent heavy fermion-like &gamma values on the order of several hundred mJ/mol K2. The lattice specific heat (C lattice) was estimated using a Debye-Einstein hybrid model. Subtracting Clattice from Ctotal, magnetic specific heat (CM) with a broad peak characteristic of low dimensional magnetism was obtained. The peak in CM was at temperature near that expected from χ(T) fits. The J values obtained from the magnetic specific heat fits were in good agreement with those obtained from χ(T) fits. Once the magnetic specific heat was accounted for, γtakes values in the expected range of few mJ/mol K2. For 3D MOFs [Mn(N3)2bpy and Fe(N3)2bpy], the existence of long range canted antiferromagnetic ordering was observed in both magnetic and specific heat measurements with phase transitions at 38 K and 20 K in the case of Mn(N3)2bpy and Fe(N3)2bpy, respectively. These transition temperatures are considered fairly high for molecular based materials. In both Mn(N3)2bpy and Fe(N3)2bpy, the χ(T) data fit well to the Heisenberg model for a diamond-type network. The transition can clearly be seen with an abrupt increase in the magnetization below TC and a shift to a higher temperature in the specific heat when measured under an applied magnetic field. The systematic approach in this work led to the successful estimate of C lattice resulting in meaningful fitting of χ(T) and Cmagnetic to the appropriate theoretical models in magnetism. It also led the discovery of ferrimagnets or canted antiferromagnets M(N3)2bpy with large coercivity and rather high transition temperature. The results of this study have been published in three articles in the Journal of Applied physics, and two manuscripts are under preparation for submission [1-5]. / Physics
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Temperature Programmed Desorption and Infrared Spectroscopic Studies of Interfacial Hydrogen Bonds for Small Molecules Adsorbed on Silica and Within Metal Organic FrameworksAbelard, Joshua Erold Robert 15 May 2017 (has links)
Hydrogen bonds are arguably the most important reversible intermolecular forces. However, surprisingly few studies of their fundamental nature at the gas-surface interface have been performed. Our research investigated sulfur mustard (HD) adsorption by characterizing interfacial hydrogen bonding and dispersion forces for the simulant molecules 2-chloroethyl ethyl sulfide (2-CEES) and methyl salicylate on well-characterized hydroxyl-functionalized surfaces (silica and UiO-66). Our approach utilized infrared spectroscopy to study specific surface-molecule interactions and temperature-programmed desorption to measure activation energies of desorption. 2-CEES has two polar functional groups, the chloro and thioether moieties, available to accept hydrogen bonds from free surface silanol groups. Diethyl sulfide and chlorobutane were investigated to independently assess the roles of the chloro and thioester moieties in the overall adsorption mechanism and to explore the interplay between the charge transfer and electrostatic contributions to total hydrogen bond strength. The results indicate that both SiOH---Cl and SiOH---S hydrogen bonds form when 2-CEES adsorbs to silica or hydroxylated UiO-66. However, a more stable configuration in which both polar groups interact simultaneously with adjacent silanol groups likely does not form. A systemaic study of chloroalkanes revealed that dispersion forces involving the methylene units in 2-CEES contribute to nearly half of the total activation energy for desorption from silica. Methyl salicylate possesses aromatic, hydroxyl, and ester functional groups, each of which is a potential hydrogen bond acceptor. We found that uptake on silica is mainly driven by the formation of carbonyl-silanol and hydroxyl-silanol hydrogen bonds with additional contributions from weaker interactions. In an effort to learn more about the SiOH---π bond, the adsorption of simple substituted benzene derivatives on silica was investigated to probe the effects of electron withdrawing and donating substituents. Results indicate that the substituted benzene derivatives adsorb to silica via a cooperative effect involving SiOH---π hydrogen bonds and additional substituent-surface interactions. The strength of the SiOH---π bond is enhanced by electron donating groups and weakened by electron withdrawing groups. / Ph. D.
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Potentiels des poly-hydroxyalcanoates (PHAs) bactériens pour l'encapsulation de molécules à visée thérapeutique / Potentials of bacterial Poly-HydroxyAlkanoates (PHA) for the encapsulation of therapeutic moleculesJain-Beuguel, Caroline 14 December 2018 (has links)
Les Poly(HydroxyAlcanoates) (PHA) sont des polymères naturels, biodégradables et biocompatibles, synthétisés par de nombreux organismes, et plus particulièrement des procaryotes. Il existe à ce jour plus de 150 types de monomères de PHA différents, accumulés chez différents genres bactériens, en tant que source d’énergie et de carbone. En effet, les granules de PHA intracellulaires sont produites en réponse à un apport en excès de sources de carbone dans l’environnement (glucides, acides gras…), couplé à une carence en éléments azotés nécessaires à la division cellulaire. De par leur caractère biodégradable et biocompatible, les PHA sont employés depuis plus de 20 ans comme biomatériaux dans les domaines pharmaceutiques et biomédicaux, notamment comme micro/nanovecteurs à visée thérapeutique. Ce doctorat met en évidence des méthodes de criblage moléculaire par PCR pour la sélection de bactéries productrices de PHA, isolées de sites hydrothermaux des océans Atlantique et Pacifique au cours de campagnes océanographiques Ifremer. Selon des protocoles de fermentation standardisés et optimisés, des polymères de poly(3-hydroxybutyrate-4-hydroxybutyrate) P(3HB4HB) d’intérêt biomédical ont été produits, puis des études taxonomiques et phylogénétiques ont été menées pour explorer la biodiversité microbienne associée aux environnements marins profonds. Ensuite, des PHA ont été modifiés par réaction thiol-ène photoactivée afin d’obtenir des copolymères hydrosolubles, adaptés pour l’enrobage de nanoparticules poreuses de type Metal-Organic Frameworks (MOF). La caractérisation physicochimique a été réalisée par différentes techniques, et notamment par SEM et STEM-EDX. Les systèmes hybrides poreux MOF-PHA ont ensuite été évalués quant à leur biocompatibilité vis-à-vis de cellules immunitaires (macrophages), par des tests de cytotoxicité et de prolifération cellulaire. Cette étude met en lumière les potentialités de cette nouvelle génération de nanovecteurs, synthétisés pour augmenter le bénéfice thérapeutique tout en minimisant les effets secondaires sur l’organisme humain. / Poly(HydroxyAlkanoates) (PHA) are natural polymers, biodegradable and biocompatible, synthesized by many organisms, especially prokaryotes. There are over 150 kinds of these polyesters, accumulated in a wide variety of bacteria as carbon and energy storage material. PHA granules are deposited intracellularly when microorganisms are cultivated in the presence of an excess of carbon source (glucids, fatty acids...) together with a nitrogenous nutrient deficiency. Due to their biodegradability and biocompatibility, PHA can be used as biomaterials in medical or pharmaceutical fields, and numerous therapeutic micro/nanovectors have already been developed over the past two decades.The present PhD research project highlighted molecular screening methods by PCR for the PHA producing Bacteria selection, isolated during Ifremer cruises from hydrothermal vents in Atlantic and Pacific oceans.According to standardized and optimized fermentation protocols, poly(3-hydroxybutyrate-4-hydroxybutyrate) P(3HB4HB) polymers of biomedical interest were produced, then taxonomic and phylogenetic studies were performed to explore microbial biodiversity associated with deep-sea environments. Next, PHA were modified by ‘click chemistry’ to obtain hydrosoluble copolymers, suitable for coating high porous Metal-Organic Frameworks (MOF) therapeutic nanoparticles. Physico-chemical characterization was performed using different techniques, and more particularly by SEM and STEM-EDX. MOF-PHA hybrid porous systems were then evaluated for their biocompatibility against immune cells (macrophages), by cytotoxicity and cellular proliferation tests. This study highlights potentials of these new generations of nanovectors, synthesized to increase the therapeutic benefit while minimizing side effects on the human body.
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