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Synthesis, fabrication and characterization of poly nanofibers and investigation of their adsorption propertiesShooto, Ntaote David 06 1900 (has links)
Ph. D. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / A major challenge for this generation is cleaning up heavy metal pollution disposed during industrial, domestic and agricultural activities. So, to obtain clean water resources, new treatment technologies are needed that can be applied to a broad range of highly toxic heavy metals in water. In this study, metal organic frameworks (MOFs) were synthesized from 1,2,4,5-tertabenzene carboxylic acid with metal salts of; cobalt, copper, iron, antimony, strontium and lanthanum through solvothermal method. The synthesized MOFs were reacted with polyvinyl alcohol (PVA) by electrospinning. To the best of our knowledge it is for the first time that such hybrid materials are synthesized and reported.
PVA/MOF materials were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analyzer (TGA). The SEM micrographs of PVA/MOFs materials showed relatively uniform nanofibers that were non-beaded and entangled. Some formed patches, while others were partially cross linked. TGA analysis revealed that PVA/MOF nanofibers exhibited higher decomposition temperature than PVA nanofibres. Thus, it confirmed the interactive force between MOF and PVA nanofibres. FTIR plots also exhibited shifts in critical functional group positions, thus it confirmed that there was a given amount of MOFs embedded in the electrospun fibrous mat.
PVA/MOFs materials were used in the adsorption of lead ions in solution to study the effects of temperature, time dependant studies and concentrations. The batch adsorption experiments were performed at five different Pb(II) ion concentrations (20, 40, 60, 80 and 100 mg/L), four different temperatures (25, 40, 60 and 80 oC), time dependent studies ranged from (5, 10, 30 and 60 min) and pH of all Pb(II) solutions were recorded to be 5.05. The results indicated that the uptake performance of PVA and PVA/MOFs nanofibers significantly changed with concentration, temperature and time. The PVA/MOFs nanofiber hybrids demonstrated greater adsorption percentage and adsorption capacity for Pb(II) ions than PVA nanofibers. PVA nanofibers showed moderate adsorption percentage and capacity performance of 25.5 % and 44.13 mg/g (meaning 44.13 mg of Pb(II) per gram of PVA nanofibers) while PVA/MOFs nanofibers showed improved percentage and capacity perfomance (PVA/Cu-MOFs 76.36 % and 152.72 mg/g), (PVA/Co-MOFs 59.41 % and 99.28 mg/g), (PVA/La-MOFs 92.27 % and 184.03 mg/g), (PVA/Cd-MOFs 83.19 % and 165.94 mg/g), (PVA/Sb-MOFs 50.66 % - 91.57 mg/g), (PVA/Sr-MOFs 58.85 % - 124.82 mg/g) and (PVA/Fe-MOFs 56.76 % - 108.82 mg/g).
The adsorption data of Pb(II) ions on PVA and all PVA/MOFs nanofibers showed that a pseudo-second order kinetic model was more suitable than a pseudo first order kinetic model. The adsorption rate was much faster on PVA/MOFs nanofibers. This is marked by lower activation energy compared to PVA nanofibers activation energy. The Temkin model did not correlate well with all the adsorption data. On the contrary, Freundlich and Langmuir isotherm models described the adsorption data adequately. All PVA/MOFs nanofibers followed Langmuir isotherm model, only PVA nanofibers followed Freundlich isotherm model.
The PVA and PVA/MOFs nanofibers gave negative values of enthalpy change (ΔHo) and negative values of Gibbs free energy change (ΔGo) showing the adsorption processes were exothermic and spontaneous. Moreover, obtained positive entropy changes (ΔSo) on PVA, PVA/Fe-MOF, PVA/Cu-MOF, PVA/Co-MOF and PVA/Sb-MOF nanofibers showed that the sorped Pb(II) ions were not restricted on the electrospun nanofibres and physisorption mechanism was dominant, while negative entropy changes (ΔSo) on PVA/Sr-MOF and PVA/La-MOF nanofibers indicated that chemisorption was more dominant. The influence of ubiquitous cations such as Ca(II) and Mg(II) on the adsorption of Pb(II) ions onto PVA and PVA/MOF nanofibers was also assessed. The results showed that the ubiquitous ions had no significant influence on the sorption of Pb(II) ions.
Current investigation provides a method to develop novel PVA/MOFs nanofibers hybrid adsorbents for water purification system. The adsorption capacities and removal achieved with the PVA/MOFs nanofibers sorbent were higher than those for PVA sorbent. The electro spun nanofiber sorbents presents an efficient alternative for pre-treating lead ions in aqueous solutions. Results from this research demonstrated that higher performance novel nanofibers, which possessed higher adsorption percentages and capacity capabilities were obtsained far exceeding some of the commonly used adsorbents, were obtained.
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EVALUATION OF SINGLE MOLECULE DIODES FABRICATED VIA ELECTRON-BEAM LITHOGRAPHY AND METAL-ORGANIC FRAMEWORKS INCORPORATING TWO NOVEL LIGANDS, A TRIGONAL PLANAR CARBOXYLATE LIGAND AND A TETRAHEDRAL TETRAZOLATE-BASED LIGANDUrig, Christina S. 17 April 2007 (has links)
No description available.
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Synthesis and Evaluation of PtW Solid-Solution Nanoparticles and Bioactive Metal-Organic Frameworks / PtW固溶体ナノ粒子および生理活性金属-有機構造体の合成と評価Kobayashi, Daiya 24 January 2022 (has links)
京都大学 / 新制・論文博士 / 博士(理学) / 乙第13460号 / 論理博第1577号 / 新制||理||1683(附属図書館) / (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2項該当 / Doctor of Science / Kyoto University / DGAM
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Investigations of Electron Transport Properties in Metal-Organic Frameworks for Catalytic ApplicationsAhrenholtz, Spencer Rae 23 August 2016 (has links)
Metal-organic frameworks (MOFs) have attracted much attention in the past few decades due to their ordered, crystalline nature, synthetic tunability, and porosity. MOFs represent a class of hybrid inorganic-organic materials that have been investigated for their applications in areas such as gas sorption and separation, catalysis, drug delivery, and electron or proton conduction. It has been the goal of my graduate research to investigate MOFs for their ability to transport electrons and store and separate gases for ultimate catalytic applications in alternative energy generation. I aim to provide new insight into the design and development of stable MOFs for such applications.
We first investigated a cobalt(III) porphyrin based MOF comprised of Co(II)-carboxylate nodes, designated as CoPIZA, for its electron transport capabilities. Thin films of CoPIZA were formed solvothermally on conductive fluorine-doped tin oxide (FTO) substrates and used for electrochemical characterization. Electrochemistry coupled with spectroscopic analysis of the CoPIZA film revealed reversible reduction of the cobalt centers of the porphyrin linkers with maintenance of the overall framework structure. The mechanism of charge transport throughout the film was facilitated by redox hopping of electrons between the metal centers of the nodes and linkers.
The ability to incorporate desired properties, such as pore functionalities or open metal centers, into frameworks makes them attractive for applications in separation of gaseous mixtures, such as CO2/N2 from combustion power plants. To investigate the selective adsorption properties, we performed gas sorption measurements on bulk MOF materials to determine their affinity toward CO2. Two Zn-based MOFs containing 2,5-pyridine dicarboxylate linkers were prepared in our laboratory and contained unsaturated Zn(II) metal centers, which possess a binding site on the metal without an activation procedure to remove bound solvent molecules. These MOFs were compared to the well-known Zn-based MOF-69C containing 1,4-benzene dicarboxylate linkers. Thermodynamic analysis of the gas sorption data revealed that the mechanism of CO2 binding involved the coordinatively unsaturated Zn(II) center. The microporous MOF also demonstrated selectivity for CO2 over N2 under the same conditions. As these materials were able to uptake CO2, their ability to transport electrons was also investigated for ultimate applications in catalysis. Electrochemical impedance spectroscopy was performed on the bulk MOF powders and was coupled with solid-state nuclear magnetic resonance spectroscopy. These results determined that the conduction mechanism proceeded via solvent molecules within the pores of the framework.
The catalytic ability toward water oxidation of two MOFs was investigated electrochemically. Initial studies focused on a cobalt-based MOF comprised of 2-pyrimidinolate (pymo) linkers, designated as Co(pymo)2, which was prepared on FTO via drop-casting and used for electrochemical experiments. At applied anodic potentials, the CoII centers of Co(pymo)2 became oxidized to form a Co-oxide species on the electrode surface, which was found to be the active catalysis for water oxidation. Further investigations utilized a notably more stable Zr-based MOF with nickel(II) porphyrin linkers, designated as PCN-224-Ni. PCN-224-Ni was prepared solvothermally on FTO and used directly for electrochemical water oxidation. The mechanism of water oxidation at PCN-224-Ni proceeds via oxidation of the porphyrin macrocycle followed by binding of water to the Ni(II) center. Cooperative proton transfer to the Zr-oxo node facilitated water oxidation with the eventual release of O2. Thorough characterization revealed that PCN-224-Ni retained its structural integrity over the course of electrochemical catalysis.
These results have allowed us a deeper understanding of the mechanisms of electron transport and conduction throughout frameworks. Specifically, the incorporation of metalloporphyrin molecules with redox active metal centers coupled with the presence of redox active metal nodes resulted in redox hopping charge transport throughout the MOF. In addition, the presence of solvent molecules in the pores of the framework provided an extended network for charge transport. We have gained insight into the structure-function relationship of MOFs for applications in selective gas sorption, where an unsaturated metal center serves as the binding site for gas molecules. Finally, through selection of the components that comprise the framework, a stable metalloporphyrin MOF was found to be capable of electrochemically facilitating the water oxidation reaction. As a result, we have gained valuable insight into the properties of frameworks necessary for charge transport and stability, which will allow for further improvements in the smart design of MOFs for catalytic applications. / Ph. D.
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Investigations of Electron, Ion, and Proton Transport in Zirconium-based Metal-Organic FrameworksCelis Salazar, Paula Juliana 16 July 2018 (has links)
Metal-Organic Frameworks (MOFs) are porous materials consisting of organic ligands connected by inorganic nodes. Their structural uniformity, high surface area, and synthetic tunability, position these frameworks as suitable active materials to achieve efficient and clean electrochemical energy storage. In spite of recent demonstrations of MOFs undergoing diverse electrochemical processes, a fundamental understanding of the mechanism of electron, proton, and ion transport in these porous structures is needed for their application in electronic devices. The current work focuses on contributing to such understanding by investigating proton-coupled electron transfer, capacitance performance, and the relative contribution of electron and ionic transport in the voltammetry of zirconium-based MOFs.
First, we investigated the effects that the quinone ligand orientation inside two new UiO-type metal-organic frameworks (2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF) have on the ability of the MOFs to achieve proton and electron conduction. The number of electrons and protons transferred by the frameworks was tailored in a Nernstian manner by the pH of the media, revealing different electrochemical processes separated by distinct pKa values. In particular, the position of the quinone moiety with respect to the zirconium node, the effect of hydrogen bonding, and the amount of defects in the MOFs, lead to different PCET processes. The ability of the MOFs to transport discrete numbers of protons and electrons, suggested their application as charge carriers in electronic devices.
With that purpose in mind, we assembled 2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF into two different types of working electrodes: a slurry-modified glassy carbon electrode, and as solvothermally-grown MOF thin films. The specific capacitance and the percentage of quinone accessed in the two frameworks were calculated for the two types of electrodes using cyclic voltammetry in aqueous buffered media as a function of pH. Both frameworks showed an enhanced capacitance and quinone accessibility in the thin films as compared to the powder-based electrodes, while revealing that the structural differences between 2,6-Zr-AQ-MOF and 1,4-Zr-AQ-MOF in terms of defectivity and the number of electrons and protons transferred were directly influencing the percentage of active quinones and the ability of the materials to store charge.
Additionally, we investigated in detail the redox-hopping electron transport mechanism previously proposed for MOFs, by utilizing the chronoamperometric response (I vs. t) of three metallocene-doped metal-organic frameworks (MOFs) thin films (M-NU-1000, M= Fe, Ru, Os) in two different electrolytes (TBAPF6 and TBATFAB). We were able to elucidate, for the first time, the diffusion coefficients of electrons and ions (De and Di, respectively) through the structure in response to an oxidizing applied bias. The application of a theoretical model for solid state-voltammetry to the experimental data revealed that the diffusion of ions is the rate-determining step at the three different time stages of the electrochemical transformation. Remarkably, the trends observed in the diffusion coefficients (De and Di) of these systems obtained in PF61- and TFAB1- based electrolytes at the different stages of the electrochemical reaction, demonstrated that the redox hopping rates inside frameworks can be controlled through the modifications of the self-exchange rates of redox centers, the use of large MOF channels, and the utilization of smaller counter anions. These structure-function relationships provide a foundation for the future design, control, and optimization of electronic and ionic transport properties in MOF thin films. / PHD / The necessity of implementing new energy storage systems that enable the utilization of clean energy in diverse technologies such as electric vehicles and smart power grids, has generated great research efforts in the field of materials science. In particular, the development of nanoscale-based materials that can be utilized in batteries and supercapacitors is essential for achieving effective and clean electrochemical energy storage. Two of the main desired properties for such materials to be employed as electrodes in energy storage devices are high surface area and the possibility of incorporating redox-active moieties that are able to store electricity.
Metal-Organic Frameworks (MOFs) are a relatively new kind of porous materials with high surface area and structural uniformity, consisting of organic ligands connected by inorganic nodes. The application of these materials in charge transport and storage is still in its early stages. Therefore, fundamental understanding of the mechanism of electron, proton, and ion transport in MOFs is necessary for a rational design of these porous structures. In order to contribute to such understanding, the present work is focus on two main concepts: (1) elucidating the effect that the tridimensional orientation of redox moieties inside the MOF could have on the charge storage performance and the ability of the material to achieve proton and electron conduction; and (2) quantifying for the first time the individual relative contribution of electron and ionic transport in MOF materials.
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Metal-cyclam based Metal-Organic Frameworks for CO₂ Chemical TransformationsZhu, Jie 20 June 2018 (has links)
Designing new materials for CO₂ capture and utilization is one of the most challenging research topics. Metal-organic frameworks (MOFs) are one of the most efficient CO₂ adsorbents, as well as an emerging class of heterogeneous catalysts for CO₂ chemical transformations. Highlighted by their high content of active centers, large internal surface areas, tunable pore size, and versatile chemical functionalities, MOFs can serve as highly stable and reusable heterogeneous catalysts and provide a great platform to explore the structure-function relationships for transforming CO₂ into useful chemicals. In this dissertation, we aim to develop a new class of metal-cyclam based robust MOFs as porous materials for CO₂ uptake as well as efficient catalysts for CO₂ chemical transformations, including CO₂ chemical fixation, CO₂ photo- and electroreduction.
Chapter 1 introduces the concept and main challenges of CO₂ capture and conversion. The potential of metal-cyclam complexes as molecular catalysts for CO₂ conversion is also mentioned. The current state of the art in designing stable MOFs and azamacrocyclic-based MOFs is briefly discussed. Finally, the strategies, challenges and future outlook of using MOF as catalysts in CO₂ chemical transformation are summarized.
Metal-organic frameworks (MOFs) as highly ordered, tunable hybrid materials have shown great promise in photon collection, energy transfer and photocatalytic reactions. In Chapter 2, the fundamental principles of energy transfer in the condensed phase are summarized, and a series of studies in light-harvesting, excited state quenching and photo-excited reactivity occurring within ruthenium-polypyridyl-doped zirconium MOFs are reviewed. The application of MOFs in energy conversion devices such as dye-sensitized solar cells (DSSC) is also discussed.
Chapter 3 reports two new robust 3D porous metal-cyclam based Zr-MOFs, VPI-100 (Cu) and VPI-100 (Ni) with potential as heterogeneous catalysts for CO2 chemical fixation. The frameworks are prepared by a modulated synthetic strategy and the structure highlighted by eight-connected Zr₆ clusters and metallocyclams as organic linkers. The VPI-100 MOFs exhibit excellent chemical stability in various organic and aqueous solvents over a wide pH range and show high CO₂ uptake capacity (up to ∼9.83 wt% adsorption at 273 K under 1 atm). Moreover, VPI-100 MOFs demonstrate some of the highest reported catalytic activity values (turnover frequency and conversion efficiency) among Zr-based MOFs for the chemical fixation of CO₂ with epoxides. The MOFs, which bear dual catalytic sites (Zr and Cu/Ni), enable chemistry not possible with the cyclam ligand under the same conditions and can be used as recoverable stable heterogeneous catalysts without losing performance.
A follow-up study of CO₂ chemical fixation using Hf analogs of VPI-100 is presented in Chapter 4. Structural characterization and catalytic performance of Hf-VPI-100 are summarized. Moreover, a detailed comparison of VPI-100 and Hf-VPI-100 is made. In situ powder X-ray diffraction (PXRD), quartz crystal microbalance (QCM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) have been used to probe the interaction between the guest molecules (CO₂/epoxide) and Hf-VPI-100. For CO₂, no specific chemical binding sites in MOFs has been observed and the uptake of CO₂ does not change the crystal structure of Hf-VPI-100. Both QCM and DRIFTs revealed the irreversible binding between the framework and 1,2-epoxybutane. The epoxide uptake per unit cell of VPI-100 MOFs and diffusion coefficients have been calculated by QCM analysis.
Transition metal complexes capable of visible light-triggered cytotoxicity are appealing potential candidates for photodynamic therapy (PDT) of cancer. In Chapter 5, two monometallic polyazine complexes, [(Ph₂phen)₂Ru(dpp)]²⁺ and [(Ph₂phen)₂Os(dpp)]⁺ (Ph₂phen = 4,7-diphenyl-1,10-phenanthroline; dpp =2,3-bis(2-pyridyl)pyrazine), were synthesized, characterized and studied as light activated drugs to kill rat malignant glioma F98 cells. Both compounds display strong absorption in visible spectrum, oxygen-mediated DNA and BSA photocleavage and significant photocytotoxicity under blue light irradiation along with negligible activity in the dark. The compounds show approximately five-fold higher cytotoxicity compared the traditional chemotherapeutic drug, cisplatin. Furthermore, [(Ph₂phen)₂Os(dpp)]⁺ shows promising photocytotoxicity in F98 rat malignant glioma cells within the phototherapeutic window with an IC50 value of (86.07±8.48) µM under red light (625 nm) irradiation.
In Chapter 6, the mixed-metal supramolecular complex, [(Ph₂phen)₂Ru-(dpp)PtCl₂]²⁺, was found to display significant DNA modification, cell growth inhibition, and toxicity towards F98 malignant glioma cells following visible light irradiation. The design of this complex has a significantly higher potential for membrane permeability than three other FDA-approved anti-cancer agents, including cisplatin, and exhibited a dramatic ten-fold higher uptake by F98 cells than cisplatin in a two-hour window. Based on studies with a rat glioma cell line, the compound has very low cytotoxicity in the dark, but results in substantial cell death upon light treatment. The complex is thus among the first to exhibit all the hallmarks of a very promising new class of PDT agents. / Ph. D. / Increased carbon dioxide (CO₂) emissions have triggered a series of environmental effects, including global warming and ocean acidification. Scientists are trying to develop new materials to capture and convert CO₂ into useful chemical products. However, the main challenge is that CO₂, the gas generated upon burning fossil fuels, has strong C=O bonds that are hard to break. In other words, it is too stable to be easily changed into other compounds. A class of highly porous materials known as metal-organic frameworks (MOFs) possess significant potential for CO₂ adsorption uptake and chemical fixation. MOFs are metal ions or clusters held together by organic linkers to make highly ordered, crystalline 3D structures with tunable porosity and functionality. The design and synthesis of MOFs is similar to playing with Legos at the molecular level; you need to pick the right pieces (metal nodes and linkers) to get your desired structure. In this dissertation, we aim to develop a new class of macrocycle complexes based stable MOFs as porous materials for CO₂ uptake as well as efficient catalysts for CO₂ chemical transformations.
We have developed two new stable three dimensional porous frameworks, VPI-100 (Cu) and VPI-100 (Ni) as catalysts for CO₂ chemical fixation. The new 3D robust MOFs named VPI-100 (VPI = Virginia Polytechnic Institute) are assembled by the reaction of zirconium oxo clusters and linkers bearing metal complexes. Using the metal complexes as the linker provides additional metal active sites in the framework that can act as accessible catalytic centers for CO₂ conversion. The VPI-100 MOFs are not only able to convert CO₂ to cyclic carbonates (important industrial chemicals) in high efficiency (~ 98%), but also can be reused for multiple cycles. The heterogeneous catalyst can be easily recovered from the reaction mixture by centrifugation and the active metal centers are earth-abundant transition metals (Cu and Ni), which are cost effective. Additionally, VPI-100 MOFs also show high CO₂ uptake capacity (up to ~10 wt%) at ambient pressure. Since the MOFs can enhance the local concentration of CO₂ around the active catalytic centers located inside the pores of the framework, these materials could be used as catalysts for flow chemistry, which is widely used in industry.
We further investigated the CO₂ chemical fixation using Hf analogs of VPI-100. Structural characterization and catalytic performance of Hf-VPI-100 are summarized. Moreover, a detailed comparison of VPI-100 and Hf-VPI-100 is made. Different analytical techniques have been used to further understand the reaction mechanism as well as the interaction between the CO₂/epoxide and the frameworks. These insights would help us to design new MOFs as better catalysts for practical applications.
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Evaluation des Metal-Organic Frameworks en adsorption et séparation des hydrocarburesPeralta, David 02 February 2011 (has links) (PDF)
L'objectif de cette thèse était d'évaluer quelques Metal-Organic Frameworks (MOFs), choisis en fonction de leur taille de pores, de leur volume poreux et de leur stabilité thermique, en adsorption et séparation des hydrocarbures. Pour étudier le comportement général des MOFs nous avons choisi des MOFs avec des centres métalliques insaturés, des MOFs à charpente anionique et des ZIFs neutres et avons étudié leur sélectivité en séparation de trois familles d'hydrocarbures, à savoir alcanes, alcènes, aromatiques. Les MOFs à centre métallique insaturé se comportent généralement comme des zéolithes polaires, les ZIFs comme des zéolithes apolaires et/ou comme des tamis moléculaires. Les adsorbants les plus prometteurs sont testés sur des séparations d'intérêt industriel telles que la séparation des isomères de xylène, la séparation des paraffines linéaires, monobranchées et di-branchées et l'adsorption sélective du thiophène en vu de l'évaluation de ces adsorbants en désulfuration des essences.
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High-throughput screening: speeding up porous materials discoveryWollmann, Philipp, Leistner, Matthias, Stoeck, Ulrich, Grünker, Ronny, Gedrich, Kristina, Klein, Nicole, Throl, Oliver, Grählert, Wulf, Senkovska, Irena, Dreisbach, Frieder, Kaskel, Stefan 31 March 2014 (has links) (PDF)
A new tool (Infrasorb-12) for the screening of porosity is described, identifying high surface area materials in a very short time with high accuracy. Further, an example for the application of the tool in the discovery of new cobalt-based metal–organic frameworks is given. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Disorder and defects in functional molecular frameworksCliffe, Matthew James January 2015 (has links)
This Thesis explores the role of structural defects and disorder and their relationship to experimental data, with a particular emphasis on molecular framework materials. The question of how we can build atomistic models of amorphous materials from experimental data without needing to make system-specific assumptions is addressed. The role of 'structural invariance', <i>i.e.</i> the limited range of distinct local atomic environments within a material, as a restraint within reverse Monte Carlo refinement (RMC) is investigated. The operation of these invariance restraints operate is shown to be system-dependent and the challenges associated with effective refinement, <i>e.g.</i> configurational 'jamming', are also investigated. A generalisation to the 'structural simplicity', <i>i.e.</i> the simplest model, holding all else constant, is most likely to be correct. Three new metrics of structural simplicity are proposed: two intrinsically three-dimensional measures of local geometric invariance and one measure of local symmetry. These metrics are shown to robustly quantify the configurational quality. The ability of these metrics to act as effective restraints for the RMC refinement of amorphous materials is demonstrated by the construction of the first data-driven tetrahedral models of amorphous silicon. The role of defects and disorder within metal–organic frameworks (MOFs) is investigated through the canonical MOF UiO-66(Hf). Through a combination of techniques, including X-ray diffuse scattering, anomalous diffraction, total scattering and electron diffraction measurements, the existence of correlated metal-cluster absences in UiO-66(Hf) is demonstrated. Furthermore the ability to synthetically tune both the interactions and concentration of defects is shown. The thermomechanical properties of defective UiO-66(Hf) are also examined. UiO-66(Hf) is shown to rapidly densify by up to 5% (ΔV/V ) on ligand elimination. The resultant densified phase exhibits colossal (≥100MK<sup>-1</sup>) volumetric negative thermal expansion (NTE); the largest reported value for any MOF. Finally, the capability to tune the physical properties of MOFs through defect incorporation is demonstrated through the defect-dependence of both the densification and the NTE.
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Nouvelles stratégies pour le traitement des tumeurs chimio et radio-résistantes : Nanodiamants hydrogénés et Solides hybrides poreux. Etude in vitro dans des systèmes 2D et 3D. / Innovative therapeutic strategies against chemo and radio-resistant cancers : hydrogenated Nanodiamonds and Metal organic frameworks. An in vitro study in 2D and 3D systems.Grall, Romain 25 June 2015 (has links)
Ce travail de thèse s’inscrit dans un contexte d’explosion des nanoparticules et de leur très grand potentiel pour des applications en cancérologie. Ainsi, deux classes de nanoparticules ont été étudiées afin de valider et de caractériser biologiquement ce potentiel. Premièrement les Nanodiamants hydrogénés (H-NDs) dont l’interaction avec les photons de l’irradiation comme générateur de stress oxidatif était au cœur du postulat physico-chimique. Nous avons non seulement validé cette hypothèse dans plusieurs lignées cellulaires de cancer du rein et du sein notamment, insensibles aux doses d’irradiation étudiées ; mais également identifié la sénescence comme étant la voie activée par le double traitement H-NDs et irradiation. Les Solides hybrides poreux sont également des matériaux prometteurs grâce à leur haut pouvoir d’encapsulation de molécules actives. Nous avons ainsi démontré l’absence de toxicité de ces composés seuls dans quatre lignées de cancer du poumon et du foie, élément essentiel avant d’envisager leur utilisation, chargés avec des principes actifs. Enfin, à l’heure où la réglementation internationale encourage le développement et l’utilisation de modèles alternatifs à l’expérimentation animale, nous avons mis au point un modèle de culture tridimensionnelle d’adénocarcinome mucosécrétant de poumon. Il est utilisé pour l’étude de la progression tumorale ainsi que pour la découverte de nouvelles molécules de chimiothérapie. / The present work focuses on nanoparticles and their great skills for oncology therapies. Two kinds of nanoparticles have been studied in order to biologically validate and characterize their features. The use of hydrogenated Nanodiamonds (H-NDs) as radio sensitizer is based on a physic-chemical postulate where they act as oxidative stress generator through interaction with irradiation. Thus we validated this hypothesis in radio resistant kidney and breast cancer cell lines and identify senescence as the main pathway after co-treatment with H-NDs and irradiation. Metal organic frameworks are also of particular interest for drug delivery because of their very important loading capacities. Here we demonstrate the biocompatibility of the empty compounds in four lung and hepatic cancer cell lines, a main point before their involvement in drug delivery strategies. Finally, following international guidelines encouraging to make animal testing more ethic, we developed a new 3D cell culture mimicking mucinous lung adenocarcinoma. This well characterized model will be used for the study of cancer development and drug screening.
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