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Synthesis, Structure And Properties Of Metal-Organic Framework (MOF) Compounds Of 5-Substituted Isophthalic AcidsSarma, Debajit 05 1900 (has links) (PDF)
Metal organic framework compounds have emerged as an important part of inorganic coordination chemistry during the last two decades. In this thesis, the metal-organic frameworks (MOFs) compounds of 5-substituted isophthalic acids have been investigated. As part of the investigations, preparation of MOF compounds of different 5-substituted isophthalic acids such as 5-aminoisophthalaic acid, 5-nitroisophthalaic acid and 5-sulphoisophthalaic acid have been accomplished. Structures of the newly synthesized compounds were established by single crystal X-ray diffraction technique. Magnetic properties of the transition metal based compounds have been studied by SQUID/PPMS magnetometer. The ligand-sensitized metal-center emission has been studied on the Eu3+ and Tb3+ doped MOF compounds of Y and La. Up-conversion luminescence properties of Nd based compound have also been studied. The labile nature of the coordinated and lattice water molecules was established by employing dynamic in-situ single crystal to single crystal structural transformation studies. In addition, the site selective substitution in homometallic MOF compounds and their subsequent thermal decomposition to mixed-metal spinel oxides have also been investigated.
In Chapter 1 of the thesis an overview of the metal-organic framework compounds is presented. In Chapter 2, the synthesis, structure and properties of 5-aminoisophthalate compounds of 3d metals and the rare earth metals are presented. In some of these compounds the coordinate and the lattice water molecules can be removed and reinserted with the retention of single crystallinity. Also some of the isostructural compounds exhibits interesting magnetic behaviors. Partial substitution of the Y3+/La3+ compounds of 5-aminoisophthalate with Eu3+/Tb3+ exhibits characteristics metal centered emission (red = Eu3+ and green = Tb3+).
In Chapter 3, the three dimensional compounds of 5-nitroisophthalate and 4, 4’-oxybisbenzoate with cobalt and the high – throughput screening in the synthesis of metal-organic frameworks (MOFs) for the Cu(CH3COO)2.H2O – NIPA – heterocyclic ligand systems are presented.
In chapter 4, the single crystal to single crystal transformation with temperature dependent dimensionality cross-over and structural reorganizations in two copper based compounds of 5-sulfoisopphthalate and 5-nitroisophthalate are presented. In chapter 5, the site selective substitution in a homometallic MOF compound and its subsequent decomposition to mixed-metal spinel oxides are presented.
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Syntheses Structural Transformations, Magnetism, Ferroelectricity and Proton Conduction of Metal Organic Frameworks (MOF) CompoundsBhattacharya, Saurav January 2015 (has links) (PDF)
The past few decades have witnessed an almost exponential increase in interest in the field of metal organic frameworks (MOFs), which can be evidenced from the large number of scientific articles being published routinely in this area.
The MOFs are crystalline hybrid materials built via the judicial use of inorganic
metal ions and organic linkers, thereby bridging the gap between purely inorganic
and organic materials. The structural versatility and the potential tunability of the MOFs imparts unique physicochemical and thermomechanical properties, which have
rendered them immensely useful in the branches of chemistry, material science,
physics, biology, nanotechnology, medicine as well as environmental engineering.
The MOFs have been shown to be promising as materials for gas storage and separation, sensors, ferroelectric and non-linear optical materials, magnetism, catalysis, drug delivery etc and researchers have been devising strategies to utilize
the MOFs to tackle a number of global challenges of the twenty-first century.
A survey of the literature reveals that the linear organic linkers, 1,4-
benzenedicarboxylic acid (BDC) and 4,4’-biphenyldicarboxylic acid (BPDC), have been
the organic linkers of choice for the construction of stable, porous and multifunctional MOFs. The aim of this thesis has been to monitor the effect that the presence of a functional group in between the benzene rings of the BPDC would have on the overall structures and the properties of the MOFs. Thus, as part of the investigations, the preparation of the MOF compounds using 4,4’-sulfonyldibenzoic acid (SDBA) and 4,4’-
azodibenzoic acid (ABA) have been accomplished. Along with the conventional
hydrothermal and solvothermal synthetic techniques, the liquid-liquid biphasic
reaction method was also utilized for the synthesis of some of the compounds. The
structures of the compounds were ascertained from single crystal X-ray diffraction
technique. Proton conductivity studies were performed on Mn based porous MOFs
using AC impedance spectroscopy. The ferroelectric behavior in a Co based porous
MOF was established using dielectric and polarization vs electric field measurements.
The labile nature of the lattice solvent molecules was established utilizing single
crystal X-ray diffraction studies and water sorption experiments. In addition, the site
selective substitution in a homometallic MOF and the subsequent conversion to a
mixed-metal spinel oxide upon thermal decomposition, have also been studied.
Chapter 1 of the thesis is a brief overview of the metal organic framework compounds and summarizes the various important structures that have been reported in literature and the interesting properties that they exhibit. In chapter 2, the proton conductivity behavior, solvent mediated single crystal to single crystal (SCSC) and related structural transformations in a family of Mn and Co based porous MOFs with SDBA have been presented. Also presented are the results of the site selective substitution of Mn by Co in a homometallic Mn based MOF and it’s
subsequent decomposition to CoMn2O4 spinel oxide nanoparticles.
In chapter 3, the syntheses, structures and the magnetic properties of the pentanuclear Mn5 based MOF compounds with SDBA have been presented. The role of the time and the temperature in the formation of the compounds has also been presented.
In chapter 4, the dehydration/rehydration mediated switchable room temperature ferroelectric behavior, the single crystal to single crystal solvent exchange studies and selective gas sorption behavior in an anionic Co based MOF with SDBA has been discussed.
In chapter 5, the use of the liquid-liquid biphasic synthetic route in the
formation of Zn and Cd based MOFs with ABA has been discussed. Structural
transformations between the one dimensional Zn based compounds and the heterogeneous catalytic studies using the Cd based compounds have also been presented.
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Surface organometallic chemistry on Metal Organic Frameworks (MOF) : synthesis, characterization and their application in catalysis / La chimie organométallique de surface appliquée aux structures organométalliques poreuses (MOF) : synthèses, caractérisations, et leurs applications en catalyseLarabi, Cherif 13 January 2011 (has links)
Les structures organométalliques poreuses (Metal Organic Framework, MOF) sont une nouvelle classe de matériaux, composées d'ions métalliques ou de clusters liés à des ligands organiques ou des complexes organométalliques dans des réseaux cristallins 1D, 2D ou 3D. Au cours de cette thèse la possibilité de construire de nouveaux MOF a été illustrée par le développement de matériaux MOF à base d’imidazolium, précurseur important pour la synthèse de catalyseurs. En outre, ce travail démontre l’utilité de la modification post-synthèse des MOFs par chimie organométallique de surface à visée catalytique : i) un MOF connu, UiO-66, avec des pores relativement petits a été fonctionnalisé avec un groupement amino et ses capacités d'adsorption de gaz ont été étudiées. ii) la synthèse de MOF a structure poreuse, CPO-27, MOF a été optimisée et utilisée comme précurseur pour produire un catalyseur d'hydrodésulfuration après l'introduction d'espèces actives, via la chimie organométallique de surface, dont les performances catalytiques ont été évaluées / Metal organic frameworks (MOF) are a new class of material, which consist of metal ions or clusters coordinated to organic ligands or metal-organic complexes and result in 1D, 2D or 3D crystalline networks. The possibility of constructing new MOF has been exemplified in this thesis by development of imidazolium based MOF, a highly important ligand system in catalysis. Moreover, this work has performed post synthesis modification via surface organometallic chemistry on existing MOF: i) a known MOF, UiO-66, with relatively small pores has been functionalized with amino group and its gas adsorption capacity has been investigated, ii) the syntheses of a 3D open structure MOF, CPO-27, MOFs have been optimized and used as a precursor to produce a hydrodesulfurization catalyst after introducing active species via surface organometallic chemistry approach, whose catalytic performances have been measured
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Etude de l'adsorption de composés organiques sur des matériaux poreux de type Metal Organic Framework (MOF)Boulhout, Mohammed 12 December 2012 (has links)
Afin de répondre aux demandes des industriels de nouveaux matériaux poreux sont testés pour de nouvelles applications ou pour améliorer les procédés existants. Les adsorbants de types Metal Organic Frameworks(MOFs) ont des structures construites à partir d'unités inorganiques reliées entre elles par des ligands organiques. La possibilité de varier ces deux entités, offre une grande diversité de structures avec des cavités de tailles contrôlées. L'objectif de cette thèse a été d'évaluer les performances des MOFs pour l'adsorption de composés organiques et de comprendre les mécanismes d'adsorption. Les deux problématiques sélectionnées sont d'intérêt pour l'industrie pétrochimique. La séparation du para-xylène des autres isomères du xylène et de l'éthylbenzene, permets de répondre à la demande de matière première pour la synthèse du polytéréphtalate d'éthylène. L'adsorption des composés azotés et soufrés (teneur fixée par des législations), permets la purification de carburants. Notre étude thermodynamique est basée sur la réalisation d'isothermes d'adsorption et la détermination d'enthalpies d'adsorption par microcalorimétrie en phase liquide. L'adsorption des vapeurs des xylènes purs a été étudiée pour comprendre l'effet du solvant. Une grande variété de comportement a été observée selon les structures des MOFs. Nous avons par exemple mis en évidence l'effet de l'empilement moléculaire des isomères du xylène sur la sélectivité des MOFs. Nous avons démontré que la flexibilité des MOFs intervient sur les interactions au cours de l'adsorption des xylènes. Nous avons mis en évidence une sélectivité des MOFs possédant un centre métallique insaturé en faveur des composés azotés / In order to meet the industrials requirements, new porous materials are tested for new applications or to improve existing processes. The Metal Organic Frameworks (MOFs) are hybrids crystalline compounds made up of clusters (or chains) of metal ions coordinated by organic linkers to form three dimensional structures. The ability to vary these two entities offers to MOFs a wide variety of organized structure with pore sizes controlled. The aim of this thesis was to evaluate the MOF performances for the adsorption of organic compounds and also understand the related adsorption mechanism. The two selected issues are of interest for the petrochemical industry. The para-xylène separation from the other xylene isomers (ortho, meta) and ethylbenzene, allows to meet the demand for raw materials in the polyethylene terephthalate (PET) synthesis. The nitrogen and sulphur compounds adsorption allows the purification of fuels (sulphur content set by legislation). We present a thermodynamic study of adsorption from solution based on the determination of adsorption isotherms by depletion method and adsorption enthalpies by microcalorimetry. The pure xylenes vapour adsorption was also studied to understand the solvent effect. A wide variety of behaviour has been observed depending on MOF structures. For example we demonstrated the effect of xylene isomers molecular packing on MOF selectivity. Furthermore we have shown that the MOF structure flexibility influence the interactions involved during xylene isomers adsorption. We also demonstrated that MOF with unsaturated metallic centres present selectivity for nitrogen compounds (Lewis acid/base).
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Cw and pulsed EPR spectroscopy of Cu(II) and V(IV) in metal-organic framework compounds: metal ion coordination and adsorbate interactionsJee, Bettina 24 October 2013 (has links) (PDF)
Metal-organic framework (MOF) compounds as a new class of porous coordination polymers consists of metal ions or clusters linked by organic molecules. They have gained recent interest because of their large surface areas and huge variety of the porous network structures. They exhibit interesting adsorption properties and therefore are potential candidates for various technical applications.
In this work, continuous wave (cw) and pulsed electron paramagnetic resonance (EPR) methods such as pulsed electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopy are applied to study metal-organic frameworks with respect to different aspects of their properties: The host-guest interactions between Cu2+ ions in [Cu3(btc)2]n (HKUST-1; btc: 1,3,5-benzenetricaboxylate) with adsorbed methanol (CH3OH), 13C enriched carbon monoxide and dioxide (13CO, 13CO2), hydrogen (H2), deuterium (D2) and mixed isotopic HD. In [Cu3(btc)2]n, the Cu2+ ions are connected to binuclear Cu/Cu paddle wheel units. Since the Cu2+ ions in the [Cu3(btc)2]n are antiferromagnetically coupled, the new compound [Cu2.97Zn0.03(btc)2]n is synthesized by isomorphous substitution containing about 1 % paramagnetic Cu/Zn paddle wheel units. The modified Cu/Zn paddle wheel units prove to be a very sensitive probe for the interactions with the adsorbed molecules.
Secondly, the exchange interactions of antiferromagnetically coupled Cu/Cu paddle wheel units as well as additional inter-paddle wheel exchange interactions between the Cu/Cu pairs are studied in [Cu2(bdc)2(dabco)]n, a layered MOF with 1,4-benzenedicaboxylate (bdc) as linker and 1,4-diazabicyclo[2.2.2]octane (dabco) acting as pillars between the layers. In comparison to [Cu3(btc)2]n, the additional inter-paddle wheel exchange interactions are much easier disturbed by incorporation of Zn2+ ions into the framework structure.
Third, the structural dynamics of the framework is investigated in the compound [Al(OH)(bdc)]n (MIL-53) which was isomorphously substituted by V(III)/V(IV) species. The 51V hyperfine structure revealed to be sensitive to the so-called breathing effect, a flexible structural behaviour upon guest adsorption/desorption or upon thermal treatment. It is shown that the aluminum ions can be substituted by vanadium but the octahedral coordination environment changes slightly to a pseudo-octahedral or a square-pyramidal coordination.
Based on the hyperfine interactions between the electron spin and the nuclear spins of the surrounding atoms, structural models can be derived from orientation-selective measurements. In such a way, structural information of materials like powder samples and adsorbate complexes can be obtained which are hardly or even not accessible by other methods.
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Design of isostructural metal-imidazolate frameworks : application for gas storageMondal, Suvendu Sekhar January 2013 (has links)
The sharply rising level of atmospheric carbon dioxide resulting from anthropogenic emissions is one of the greatest environmental concerns facing our civilization today. Metal-organic frameworks (MOFs) are a new class of materials that constructed by metal-containing nodes bonded to organic bridging ligands. MOFs could serve as an ideal platform for the development of next generation CO2 capture materials owing to their large capacity for the adsorption of gases and their structural and chemical tunability. The ability to rationally select the framework components is expected to allow the affinity of the internal pore surface toward CO2 to be precisely controlled, facilitating materials properties that are optimized for the specific type of CO2 capture to be performed (post-combustion capture, precombustion capture, or oxy-fuel combustion) and potentially even for the specific power plant in which the capture system is to be installed. For this reason, significant effort has been made in recent years in improving the gas separation performance of MOFs and some studies evaluating the prospects of deploying these materials in real-world CO2 capture systems have begun to emerge.
We have developed six new MOFs, denoted as IFPs (IFP-5, -6, -7, -8, -9, -10, IFP = Imidazolate Framework Potsdam) and two hydrogen-bonded molecular building block (MBB, named as 1 and 2 for Zn and Co based, respectively) have been synthesized, characterized and applied for gas storage. The structure of IFP possesses 1D hexagonal channels. Metal centre and the substituent groups of C2 position of the linker protrude into the open channels and determine their accessible diameter. Interestingly, the channel diameters (range : 0.3 to 5.2 Å) for IFP structures are tuned by the metal centre (Zn, Co and Cd) and substituent of C2 position of the imidazolate linker. Moreover hydrogen bonded MBB of 1 and 2 is formed an in situ functionalization of a ligand under solvothermal condition. Two different types of channels are observed for 1 and 2. Materials contain solvent accessible void space. Solvent could be easily removed by under high vacuum. The porous framework has maintained the crystalline integrity even without solvent molecules.
N2, H2, CO2 and CH4 gas sorption isotherms were performed. Gas uptake capacities are comparable with other frameworks. Gas uptake capacity is reduced when the channel diameter is narrow. For example, the channel diameter of IFP-5 (channel diameter: 3.8 Å) is slightly lower than that of IFP-1 (channel diameter: 4.2 Å); hence, the gas uptake capacity and Brunauer-Emmett-Teller (BET) surface area are slightly lower than IFP-1. The selectivity does not depend only on the size of the gas components (kinetic diameter: CO2 3.3 Å, N2 3.6 Å and CH4 3.8 ) but also on the polarizability of the surface and of the gas components. IFP-5 and-6 have the potential applications for the separation of CO2 and CH4 from N2-containing gas mixtures and CO2 and CH4 containing gas mixtures. Gas sorption isotherms of IFP-7, -8, -9, -10 exhibited hysteretic behavior due to flexible alkoxy (e.g., methoxy and ethoxy) substituents. Such phenomenon is a kind of gate effects which is rarely observed in microporous MOFs. IFP-7 (Zn-centred) has a flexible methoxy substituent. This is the first example where a flexible methoxy substituent shows the gate opening behavior in a MOF. Presence of methoxy functional group at the hexagonal channels, IFP-7 acted as molecular gate for N2 gas. Due to polar methoxy group and channel walls, wide hysteretic isotherm was observed during gas uptake. The N2 The estimated BET surface area for 1 is 471 m2 g-1 and the Langmuir surface area is 570 m2 g-1. However, such surface area is slightly higher than azolate-based hydrogen-bonded supramolecular assemblies and also comparable and higher than some hydrogen-bonded porous organic molecules. / Metallorganische Gerüstverbindungen (MOFs) sind eine neue Klasse von porösen Koordinationspolymeren, die aus Metall-Knoten und verbrückenden Liganden bestehen.
MOFs können Gasgemische trennen und Gase speichern. Aufgrund ihres modularen Aufbaus können die MOF-Eigenschaften systematisch variiert werden. Ein wichtiges Ziel für das Design von MOFs ist die Synthese von Materialien, die eine hohe selektive Aufnahmefähigkeit und -kapazität für Kohlenstoffdioxid besitzen.
Im Rahmen der Arbeit ist es gelungen sechs neue MOFs (IFP-5, -6, -7, -8, -9 und -10) zu synthetisieren. Diese MOFs tragen die Kurzbezeichnung IFP. IFP steht als Abkürzung für Imidazolat-Framework-Potsdam (Imidazolat-basierte Gerüstverbindung Potsdam). In diesen IFPs wurde der Metallknoten (Zink, Cobalt, Cadmium) und der Brückenligand, ein 2-substituiertes Imidazolat-amid-imidat, in der Position variiert, um gute und selektive Sorptionseigenschaften für Kohlenstoffdioxid zu erzielen. Von den synthetisierten Verbindungen hat das IFP-5 die besten Sorptionseigenschaften für Kohlenstoffdioxid.
Es konnte weiter gezeigt werden, dass sich die IFP-Struktur bei der Wahl von geeigneten Substituenten 2, wie z.B. Methoxy und Ethoxy auch für das Design von gate-opening (Tür-öffnenden) Effekten eignet. Diese Effekte können wiederum genutzt werden, um selektiv Gasmischungen zu trennen.
Wenn man das 4,5-Dicyano-2-methoxy-imidazol in Gegenwart von Zink- und Cobalt-Salzen unter solvothermalen Bedingungen zur Reaktion bringt, erhält man beispiellose supramolekulare Wasserstoffbrückenbindungen zu einem dreidimensionalen Netzwerk, die mit Kanälen verknüpft sind. Diese Kanäle können von Lösungsmittelmolekülen (Wasser und Dimethylformamid) befreit werden und Gase aufnehmen.
Insgesamt besteht nun die neue MOF-Klasse der Imidazolat-basierten IFPs aus Vertretern. Das Potential der 2-substituierten 4,5-Dicyanoimidazole ist nicht nur auf die Bildung von porösen Koordinationspolymeren beschränkt, sondern kann auch für die Synthese von bisher unbekannten supramolekularen Strukturen genutzt werden.
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Pillared Paddle-Wheel Frameworks als stationäre Phasen für gaschromatographische TrennungenBöhle, Tony 20 June 2013 (has links) (PDF)
Metal-organic Frameworks (MOFs) sind eine neue Klasse poröser und kristalliner Feststoffe, die durch ihren modularen Aufbau aus organischen und anorganischen Einheiten einzigartige Eigenschaften unter den porösen Materialien besitzen. Im Mittelpunkt dieser Arbeit steht ihre Anwendung im Bereich der Gaschromatographie, die bislang nur wenig erforscht ist. Dazu werden drei verschiedene MOFs aus der Reihe der „Pillared Paddle-Wheel Frameworks“ (PPFs) in GC Kapillarsäulen abgeschieden und untersucht. Durch systematische Messungen kann gezeigt werden, dass PPFs nicht nur zur Analyse flüchtiger organischer Verbindungen, sondern auch für spezielle Anwendungen wie Größenausschlusschromatographie und Enantiomerentrennungen anwendbar sind. Weiterhin wurden Adsorptionsenthalpien und -entropien sowie Diffusionskonstanten und Massenübergangskoeffizienten für ein breites Analytenspektrum bestimmt.
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Análise estrutural e termodinâmica do composto {[Zn(2,5-pdc)(H2O)2].H2O}n nas formas desidratada e delaminadaLima, Larissa Lavorato 22 February 2017 (has links)
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Previous issue date: 2017-02-22 / As redes metalorgânicas (ou MOF, do inglês Metal-Organic Frameworks) pertencem à classe dos polímeros de coordenação (ou CP, do inglês coordination polymers) e exibem características como porosidade e cristalinidade. Em particular, as MOF bidimensionais têm despertado o interesse no desenvolvimento de uma nova geração de dispositivos ópticos e eletrônicos. A capacidade de formação de filmes finos de algumas dessas MOF as tornam materiais mais atraentes. A MOF bidimensional estudada neste trabalho foi a rede {[Zn(2,5-pdc)(H2O)2].H2O}n (2,5-pdc = 2,5-piridinodicarboxilato), ZnPDC2D. A MOF 2D foi sintetizada e caracterizada por diferentes técnicas experimentais e também foi estudada por simulação computacional. O modelo do ZnPDC2D foi otimizado por dois métodos (PBE e PBE-D2), os quais descreveram bem os parâmetros estruturais. A partir do modelo do ZnPDC2D, foi elaborada uma proposta para o processo de desidratação e assim, sugerindo a formação de três novas fases (d1-ZnPDC2D, d2-ZnPDC2D e d3-ZnPDC2D). A temperatura em que o ZnPDC2D sofre amorfização foi determinada através da medida de difração de raios X com aumento de temperatura in situ e pôdese inferir que a fase amorfa sofre uma transformação reversível após ser exposta ao ambiente. A termodinâmica da primeira etapa da desidratação mostra que o funcional PBE é mais adequado para descrever a espontaneidade da reação. Esperase obter as estruturas por meio de análises de difração de raios X por policritais e refinamento pelo método de Rietveld. O trabalho também reporta a simulação da energia de formação do monofilme pelos métodos PBE e PBE-D2. As análises de propriedades eletrônicas para todas as estruturas citadas foram executadas e discutidas conforme os processos e mudanças envolvidas. / Metal-organic frameworks (MOFs) belong to the class of coordination polymers (CPs) and exhibit properties such as porosity and crystallinity. In particular, twodimensional MOFs have attracted interest in the development of a new generation of optical and electronic devices. The possibility of thin film formation of some of these MOFs makes them more attractive materials. The twodimensional MOF studied in this work was the network {[Zn(2,5-pdc)(H2O)2].H2O}n (2,5-pdc = 2,5-pyridinedicarboxylate), ZnPDC2D. The MOF 2D was synthesized and characterized by different experimental techniques and was also studied by computer simulation. Two optimized ZnPDC2D structures were obtained by distinct methods (PBE and PBE-D2) with a good description of their parameters. The structure obtained from the simulation of the dehydration process suggest the formation of three new phases (d1-ZnPDC2D, d2-ZnPDC2D and d3-ZnPDC2D). The temperature at which ZnPDC2D undergoes amorphization was determined by Xray podwer diffraction measurement with in situ temperature rise and it could be inferred that the amorphous phase undergoes a reversible transformation after being exposed to the environment. The thermodynamics of the first stage of dehydration shows that the PBE functional is adequate to describe the spontaneity of the reaction. The structures are expected to be obtained by Xray podwer diffraction analysis and refinement by the Rietveld method. Thise work also reports the simulation of the monofilm by the PBE and PBE-D2 methods. The analyses of electronic properties for all th cited structures were performed and discussed according to the processes and changes involved.
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Understanding Gas Sorption Mechanisms in Metal–Organic Materials via Computational ExperimentationForrest, Katherine A. 10 November 2017 (has links)
Metal–organic materials (MOMs), a type of porous crystalline structure composed of organic ligands jointed with metal ions, have captured the interest of scientists as potentially useful in gas sorption applications. Some of the most crucial avenues of investigation are in H2 storage (for use as a clean burning fuel source) and CO2 capture and sequestration (to remove the greenhouse gas from the environment).
A major advantage of MOMs for such applications is their high variability in terms of physical dimensions and chemical moieties, based on composition and synthesis conditions, making them potentially customizable for specific application if necessary structural characteristics are known. Computational experimentation is an important avenue for determining such specifications as it allows examination of gas/MOM interaction at the molecular level. In this dissertation a number of MOM structure are computationally studied in order to elucidate gas sorption mechanisms. These systems were probed by classical simulation using grand canonical Monte Carlo with a carefully chosen set of intermolecular interaction parameters. While the focus of this work is specifically H2 and CO2 sorptive behavior, the insights gained from simulation extend beyond these specific applications.
Addressed first are a series of MOMs with rht topology, which possesses asymmetric copper paddle-wheels and easily functionalized linkers. Beginning with a prototypical structure and then branching out into more chemically interesting variants revealed surprising gas sorption behavior about the metal paddle-wheels (with a definite preference for one copper over its counterpart). A synthetic strategy for controlling the preferred open-metal sorption site through the inclusion of electron rich functionality in the linker bodies, was also revealed. An additional MOM with similar composition components, exhibiting zyg topology, also showed this metal preference effect on the asymmetric paddle-wheels.
A second class of MOMs, composed of square-pillared grids and known as the SIFSIX series (due to the inclusion of SiF62− as pillaring units) was also examined. These structures have been shown excellent results for CO2 sorption making the elucidation of the sorptive mechanisms of great interest. Six different structures were examined, probing the effects of linker length, metal selection, and interpenitration of unbonded scaffolds. The nature of the CO2-MOM sorption interactions were revealed through simulation and provided insights regarding the synergistic effect of pore dimensions and SiF62− functionality for specifying specific behavior (i.e. high selectivity vs. high uptake).
A final MOM, composed of Y3+ ions and chemically complex linkers, was also examined. Disorder in the crystallographic data (e.g. single atoms with multiple positions) indicated the coexistance of notably different unit cells in the same system. Nevertheless, simulations revealed favored sorption sites in conjunction with results from physical experimentation.
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Homo-and Hetero-Metallic Supramolecular Assemblies : Synthesis, Structures and CharacterizationPramanik, Sunipa January 2013 (has links) (PDF)
The work highlighted in this dissertation comprises of syntheses and characterizations of coordination driven supramolecular compounds. The synthesized complexes are characterized by IR spectroscopy, multinuclear NMR spectroscopy and single crystal structure determination.
Chapter 2: In this chapter we attempted to make a three dimensional self-assembled cage by the reaction between N, N’, N’’- tris(3-pyridyl)trimesic amide a tritopic donor and Pt(II) based 90° ditopic acceptor cis-(dppe)Pt(II)(OTf)2 [dppe = 1,2-bis(diphenylphosphino)ethane]. It resulted in a trigonal bipyramidal structure. The cage was characterized by single crystal XRD and FT-IR spectra.
Chapter 3: In this chapter we have reported the synthesis and characterization of two hereby unknown metal containing carboxylic acid ligands containing the Pt-ethynyl moiety. Also we have shown the preparation and structure analysis of a copper containing metal-organic framework incorporating one of the Pt-ethynyl containing carboxylic acid ligand. This has resulted in the formation of a very interesting hetero-metallic MOF which is quite uncommon in literature.
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