Lewis acids are widely used in the pharmaceutical industry, generally homogeneously, to perform reactions such as C-C or C=N bond formation and acetalisation. Typically, metal salts such as those of Ti, Fe and especially Sc are used, the last typically as the triflate. Metal organic frameworks (MOFs) containing such metals should act as heterogeneous, removable and reusable catalysts for similar reactions if they can be prepared in stable forms and with large, open pores and metal cation sites that can be rendered coordinatively unsaturated. Families of novel MOFs with different structure types and cations have therefore been prepared and their activity has been examined in carbonyl ene C-C bond forming reactions, Friedel-Crafts-Michael additions and in imine formation reactions. Their activities have been compared with those of the well-known HKUST-1(Cu), MIL-100(Fe) and MIL-101(Cr) solids examined as catalysts previously. In particular, divalent transition metal bisphosphonates and dicarboxylates with pore sizes from 10 – 20 Å and scandium carboxylates (MIL-68(Sc), MIL-88D(Sc), MIL-100(Sc), MIL-101(Sc)) have been tested. Synthetic procedures were optimised according to commercial constraints for the known MOFs STA-12(Ni) and MIL-100(Sc). While good activities are observed for Ni-based MOFs and in a number of the scandium-based solids, MIL-100(Sc) is by far the best Lewis acid catalyst for a range of reactions. In particular, MIL-100(Sc) is very active even when used without pre-dehydration, is readily recyclable with minor loss of activity and shows fully heterogeneous activity. It outperforms both MIL-100(Fe) and MIL-101(Cr), each commonly reported as versatile catalysts in the literature. Careful synthesis of bulky substrates shows that the activity is derived from reactions within the internal pore system. Furthermore, MIL-100(Sc) is able to perform tandem reactions - such as dehydration followed by carbonyl ene reaction - in which the Lewis acid sites catalyse two steps. The Lewis acidic sites of the excellent Lewis acid catalyst MIL-100(Sc) has been examined in detail by in situ IR using adsorption of CO and CD₃CN as probe molecules and compared with other MIL-100 materials. The work has been extended to the examination of MOFs containing two different metals, by substitutional approaches within the metal nodes (e.g. Sc-Al, Sc-Fe, Sc-Cr, Sc-Ni, Sc-Co within the trimeric M₃O(O₂C-)₆ nodes of MIL-100). In addition, series of Sc-Fe MIL-100 materials have been prepared that contain α-Fe₂O₃ nanoparticles in the pores of the structure. These composites show higher specific catalytic activity for Lewis acid catalysis than MIL-100(Sc), even though some scandium has been replaced with iron: the origin of this behaviour is discussed. MIL-100(Sc/Fe) has also been explored as a bifunctional catalyst in tandem Friedel-Crafts-oxidation reactions. MIL-100(Sc₆₀/Fe₄₀) was found to give exceptionally high conversions in the Friedel-Crafts-oxidation tandem reaction of 2-methyl indole and ethyl trifluoropyruvate to form a ketone, outperforming the many other materials tested and giving the best balance of the two different types of catalytic sites required to catalyse the reaction. MIL-100(Sc) has also been prepared containing 50% of mono-fluorinated trimesate ligands in the framework for the first time. This fluorinated MIL-100(Sc) has been post-synthetically modified by addition of a di-phenylphosphino group as confirmed by solid state NMR. This can act as a starting point for the future generation of MOF-supported metal phosphine catalysts.

Thesis advisor: Dunwei Wang / Metal nanocrystals with size and shape control have great potential in heterogeneous catalysis. Controllable encapsulation of well-defined metal nanoparticles into the novel porous materials results in new multifunctional nanomaterials. The core-shell nanostructure can enhance the selectivity, durability, or reactivity of the catalysts and even provide additional functionalities. Metal-organic frameworks (MOFs) are a class of novel crystalline nanoporous materials, with well-defined pore structures and distinctive chemical properties. Using MOFs as the encapsulating porous materials has drawn great interest recently due to their tunable structures and properties. However, it could be challenging to grow another porous material layer on metal surface due to the unfavorable interfacial energy. In this work we develop a new concept of colloidal synthesis to synthesize the metal@MOF core-shell nanostructures, in which a layer of self-assembled molecules directed the growth and alignment between two materials. Surfactant cetyltrimethylammonium bromide (CTAB) is designated to facilitate the overgrowth of MOF onto metal surface, and an alignment between the {100} planes of the metal and {110} planes of the MOF can be observed. By utilizing the same concept, a third layer of mesoporous silica could also be coated on the MOF shell with assistance of CTAB. And our method could be a general strategy to fabricate multiple-layer MOF materials. / Thesis (MS) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Chia-Kuang (Frank) Tsung / Exchange reactions have enabled a new level of control in the rational, stepwise preparation of metal-organic framework (MOF) materials. However, their full potential is limited by a lack of understanding of the molecular mechanisms by which they occur. This dissertation describes our efforts to understand this important class of reactions in two parts. The first reports our use of a linker exchange process to encapsulate guest molecules larger than the limiting pore aperture of the MOF. The concept is demonstrated, along with evidence for guest encapsulation and its relation to a dissociative linker exchange process. The second part describes our development of the first quantitative kinetic method for studying MOF linker exchange reactions and our application of this method to understand the solvent dependence of the reaction of ZIF-8 with imidazole. This project involved the collection of the largest set of rate data available on any MOF linker exchange reaction. The combination of this dataset with small molecule encapsulation experiments allowed us to formulate a mechanistic model that could account for all the observed kinetic and structural data. By comparison with the kinetic behavior of complexes in solution, we were able to fit the kinetic behavior of ZIF-8 into the broader family of coordination compounds. Aside from the specific use that our kinetic data may have in predicting the reactivity of ZIF linker exchange, we hope that the conceptual bridges made between MOFs and related metal−organic compounds can help reveal underlying patterns in behavior and advance the field. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

This thesis is built upon two areas of research concerning metal-organic frameworks (MOFs). The first focuses on the functionalisation of MOFs via post-synthetic modification (PSM). The second involves the investigation on the potential of MOFs as hosts for insect pheromones. Chapter 1 introduces the field of MOF chemistry, and covers their properties along with a brief description of their applications. The concept of PSM is introduced and a review of recent literature given. The aims of the thesis are also detailed at the end of this chapter. Chapter 2 describes the PSM of [Zr6O4(OH)4(BDC-NH2)6], UiO-66-NH2, via Aza-Michael reactions. Different functionalities were successfully introduced into its pores and the degrees of conversion were determined via 1H NMR spectroscopy. Gas sorption measurements (CO2 and N2) of the PSM products were carried out and compared. In particular, two PSM products were shown to exhibit higher CO2 over N2 selectivity than that for the starting MOF, UiO-66-NH2. Chapter 3 describes a new PSM route in obtaining azole-functionalised MOFs via Mannich reactions. The amino groups in three different MOFs were converted into a range of azole-functionalised MOFs with conversions up to 100%. In particular, one of the PSM reactions afforded a new material, formulated as [Zn3(BDC-NH2)1.32(BDC-NHCH2N2C3H3)1.68(C6H12N2)], based on single crystal X-ray crystallography, 1H NMR and TGA analyses. Gas sorption studies demonstrate increased selectivity for CO2 over N2 for the PSM products. One of the modified MOFs was shown to exhibit a high Hg(II) uptake from aqueous solutions. Chapter 4 introduces the concept of using MOFs as hosts for ant pheromones. The factors which influenced the pheromone loading in zinc and zirconium based MOFs were investigated. The MOFs containing the linker BDC-NHPr (2-(propylamino)benzene-1,4-dicarboxylate) were found to be effective at hosting two types of ant pheromones, 3-octanone and (S)-4-methyl-3-heptanone.

Les travaux décris dans cette thèse rapportent la conception de Metal-Organic Frameworks (MOFs) photoactifs et leur immobilisation sur surface dans le but d’obtenir et d’étudier des SurMOFs (Surface anchored Metal-Organic Frameworks) propices aux processus photoinduits dans le cadre de la photosynthèse artificielle. Pour accomplir cela, nous avons synthétisé différents ligands photoactifs et réalisé leur immobilisation sur surface à l’aide de la croissance épitaxiale en phase liquide. Ainsi, différents SurMOFs à base de zinc(II), présentant tous une structure de type SurMOF-2, ont été préparés avec succès. Les premiers matériaux obtenus à base de ligands rylènes (naphtalène dimide : NDI et pérylène diimide : PDI) ont mis en avant de fortes interactions  entre les chromophores au sein du SURMOF, causant une perte de la luminescence. Une deuxième génération de ligands plus encombrés a été synthétisée. Ils ont conduit à des SurMOFs luminescents et siège de transferts d’énergie interligands. Ces premiers travaux ont mis en avant l’impact de la disposition des ligands dans le matériau sur les propriétés photoniques. Par ailleurs, des SurMOFs constitués de ligands dicétopyrrolopyrrole (DPP) et d’anthracène (ADP) ont été synthétisés. L’étude de leurs propriétés photoniques alliée à des calculs théoriques ont montré que le transfert d’énergie au sein de ce SurMOF ne se fait pas de manière isotrope. Enfin, un SurMOF à partir de ligand DPP portant des fonctions réactives (azoture) a été synthétisé et nous avons pu greffer différentes molécules par réaction de cyclo-addition de type Huisgen, dont un accepteur d’électron, à sa périphérie par modification post-synthétique. / The aim of this thesis was the development of photoactive Metal-Organic Frameworks (MOFs) and their immobilizations on surface to obtain and study SurMOFs (Surface anchored Metal-Organic Frameworks) to investigate photoinduced processes in the context of the artificial photosynthesis. Towards this goal, we have synthesized photoactive ligands and immobilized them on surfaces using liquid phase epitaxy (LPE) in a layer-by-layer (LbL) fashion. Thus, different zinc (II) based SurMOFs, featuring a SurMOF-2 structure, were successfully prepared. The first rylene- (naphthalene diimide: NDI and perylene diimide: PDI) based SurMOFs described in this thesis showed strong  interactions between the chromophores within the MOF, causing the quenching of the luminescence. A second generation of ligands, sterically hindered, was then synthesized. They lead to luminescent SurMOFs showing efficient ligand-to-ligand energy transfer. These first results highlight the impact of linker arrangement within the material on its photonic properties. Furthermore, diketopyrrolopyrrole (DPP) and anthracene (DPA) based SurMOFs were prepared. The study of their photonic properties coupled with theoretical calculations showed that energy transfers, occurring within SurMOF-2 type materials, were not isotropic. Finally, a SurMOF, made out of a DPP ligand bearing reactive moieties (azide), was synthesized and was functionalized with different kinds of molecules, including an electron acceptor, at the periphery by post-synthetic modification using the Huisgen cycloaddtion reaction.

Intermolecular potential energy functions for CO2 have been developed from first principles for use in heterogeneous systems, including one with explicit polarization. The intermolecular potentials have been expressed in a transferable form and parameterized from nearly exact electronic structure calculations. Models with and without explicit many-body polarization effects, known to be important in simulation of interfacial processes, are constructed. The models have been validated on pressure-density isotherms of bulk CO2 and adsorption in three metal-organic framework (MOF) materials. The present models appear to offer advantages over high quality fluid/liquid state potentials in describing CO2 interactions in interfacial environments where sorbates adopt orientations not commonly explored in bulk fluids. Thus, the nonpolar CO2-PHAST and polarizable CO2-PHAST* potentials are recommended for materials/interfacial simulations.

The present thesis proposes to explore the potential of Zeolitic Imidazolate Framework ZIFs for CO2 capture applications in the conditions required by the Pressure Swing Adsorption separations process. Molecular modelling methods, combining Monte Carlo, Density Functional Theory and ab-initio simulations, were employed to mimic pure and mixture gas adsorption in ZIF materials. A transferable Force Field specifically developed for ZIFs materials is used to characterize a large variety of frameworks. Theses studies enable us to better understand the phenomena acting during adsorption process. Thereby several innovative modifications are proposed to enhance the ZIFs properties for CO2 capture and a series of hypothetical ZIFs are designed, characterized and compared to existing materials. The results cumulated during this thesis were then summarized to propose a first correlative model able to predict ZIF properties from a set of solids descriptors. This study enables to guide the structure design to optimize the ZIF properties.

abstract: Metal Organic Frameworks(MOFs) have been used in various applications, including sensors. The unique crystalline structure of MOFs in addition to controllability of their pore size and their intake selectivity makes them a promising method of detection. Detection of metal ions in water using a binary mixture of luminescent MOFs has been reported. 3 MOFs(ZrPDA, UiO-66 and UiO-66-NH2) as detectors and 4 metal ions(Pb2+, Ni2+, Ba2+ and Cu2+) as the target species were chosen based on cost, water stability, application and end goals. It is possible to detect metal ions such as Pb2+ at concentrations at low as 0.005 molar using MOFs. Also, based on the luminescence responses, a method of distinguishing between similar metal ions has been proposed. It is shown that using a mixture of MOFs with dierent reaction to metal ions can lead to unique and specic 3D luminescence maps, which can be used to identify the present metal ions in water and their amount. In addition to the response of a single MOF to addition of a single metal ion, luminescence response of ZrPDA + UiO-66 mixture to increasing concentration of each of 4 metal ions was studied, and summarized. A new peak is observed in the mixture, that did not exist before, and it is proposed that this peak requires metal ions to activate / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2018

Metal organic frameworks (MOFs) are a class of nanoporous materials composed through self-assembly of inorganic and organic structural building units (SBUs). MOFs show great promise for many applications due to their record-breaking internal surface areas and tunable pore chemistry. This thesis work focuses on gas separation applications of MOFs in the context of carbon capture and storage (CCS) technologies. CCS technologies are expected to play a key role in the mitigation of anthropogenic CO2 emissions in the near future. In the first part of the thesis, robust machine learning quantitative structure-property relationship (QSPR) models are developed to predict CO2 working capacity and CO2/H2 selectivity for pre-combustion carbon capture using the most topologically diverse database of hypothetical MOF structures constructed to date (358,400 MOFs, 1166 network topologies). The support vector regression (SVR) models are developed on a training set of 35,840 MOFs (10% of the database) and validated on the remaining 322,560 MOFs. The most accurate models for CO2 working capacities (R2 = 0.944) and CO2/H2 selectivities (R2 = 0.876) are built from a combination of six geometric descriptors and three novel y-range normalized atomic-property-weighted radial distribution function (AP-RDF) descriptors. 309 common MOFs are identified between the grand canonical Monte Carlo (GCMC) calculated and SVR-predicted top-1000 high-performing MOFs ranked according to a normalized adsorbent performance score. This work shows that SVR models can indeed account for the topological diversity exhibited by MOFs. In the second project of this thesis, computational simulations are performed on a MOF, CALF-20, to examine its chemical and physical properties which are linked to its exceptional water-resisting ability. We predict the atomic positions in the crystal structure of the bulk phase of CALF-20, for which only a powder X-ray diffraction pattern is available, from a single crystal X-ray diffraction pattern of a metastable phase of CALF-20. Using the predicted CALF-20 structure, we simulate adsorption isotherms of CO2 and N2 under dry and humid conditions which are in excellent agreement with experiment. Snapshots of the CALF-20 undergoing water sorption simulations reveal that water molecules in a given pore adsorb and desorb together due to hydrogen bonding. Binding sites and binding energies of CO2 and water in CALF-20 show that the preferential CO2 uptake at low relative humidities is driven by the stronger binding energy of CO2 in the MOF, and the sharp increase in water uptake at higher relative humidities is driven by the strong intermolecular interactions between water. In the third project of this thesis, we use computational simulations to investigate the effects of residual solvent on Ni-BPM’s CH4 and N2 adsorption properties. Single crystal X-ray diffraction data shows that there are two sets of positions (Set 1 and 2) that can be occupied by the 10 residual DMSO molecules in the Ni-BPM framework. GCMC simulations of CH4 and N2 uptake in Ni-BPM reveal that CH4 uptake is in closest agreement with experiment when the 10 DMSO’s are placed among the two sets of positions in equal ratio (Mixed Set). Severe under-prediction and over-prediction of CH4 uptake are observed when the DMSO’s are placed in Set1 and Set 2 positions, respectively. Through binding site analysis, the CH4 binding sites within the Ni-BPM framework are found to overlap with the Set 1 DMSO positions but not with the Set 2 DMSO positions which explains the deviations in CH4 uptake observed for these cases. Binding energy calculations reveal that CH4 molecules are most stabilized when the DMSO’s are in the Mixed Set of positions.

Some of the challenges faced when developing novel functional materials, cannot be resolved without the correct understanding of their structure‐property relationships. Metal‐organic frameworks (MOFs) constitute a representative example where in-depth structural knowledge can greatly help improve and optimise their application into industrially relevant settings. Fortunately, the inherent crystalline nature of MOFs allows for analysis using the wide range of crystallographic experimental techniques that are currently available. This work covers the study of the structural properties of a particular family of MOFs, which have shown significant potential as molecular sieves and for gas storage. Sc-based MOFs first attracted attention for their particularly robust and inert nature, bypassing some of the physical challenges many MOFs have when undergoing industrial implementation. After an initial review of the state of the art in the field of MOFs and the techniques utilised to analyse their properties, this work then focuses on the mechanical properties of a series of functionalised and unfunctionalised Sc‐dicarboxylate MOFs. Using nano‐indentation techniques and high‐pressure crystallography, the hardness and elasticity of these materials are correlated to their different structural features, confirming their relative robustness when compared to other MOFs in the literature. An interesting property of Sc2BDC3 is its selective uptake of CO2 over other fuel-related gases such as CH4 and CO. In this context, the in situ adsorption crystallographic analysis of Sc2BDC3 and its amino‐functionalised derivative Sc2(BDC‐NH2)3 (BDC‐NH2 = 1,4‐amino‐2‐benzenedicarboxylate) is described, as performed using the gas cell set up of beamline I19 at the Diamond Light Source synchrotron. This study is the first example of a mixed gas atmosphere experiment using single‐crystal diffraction, which in conjunction with in silico, adsorption and breakthrough experiments, provides direct insight into the interactions that drive the selective behaviour of both frameworks. Following this, the MOF Sc2BDC3 (BDC = 1,4‐benzenedicarboxylate), is selected as a case study for branched and unbranched alkane separation. Here, high‐pressure crystallography shows how these relatively oversized guest molecules, can be forced at thousands of atmospheres of pressure inside the narrow triangular channels (< 4 Å diameter) of the framework. It is also possible to resolve the structural changes the framework undergoes upon uptake of the different guests, as well as locate the adsorption sites of the hydrocarbons in the pores of Sc2BDC3, which can be then correlated to the gas adsorption behaviour of the different guests. To conclude, the high‐pressure inclusion study of both CO2 and CH4 inside Sc2BDC3 shows how combining cryoloading techniques and molecular crystallography for the first time, can provide improved models of the adsorbed gaseous guests inside Sc2BDC3. This example not only provides a novel alternative in which to study more easily the adsorption sites in MOFs via diffraction techniques, but also reveals some of the interesting structural behaviour MOFs can have in these extreme conditions.