Interfacial Bonding between a Crystalline Metal-Organic Framework and an Inorganic Glass.

The interface within a composite is critically important for the chemical and physical properties of these materials. However, experimental structural studies of the interfacial regions within metal-organic framework (MOF) composites are extremely challenging. Here, we provide the first example of a new MOF composite family, i.e., using an inorganic glass matrix host in place of the commonly used organic polymers. Crucially, we also decipher atom-atom interactions at the interface. In particular, we dispersed a zeolitic imidazolate framework (ZIF-8) within a phosphate glass matrix and identified interactions at the interface using several different analysis methods of pair distribution function and multinuclear multidimensional magic angle spinning nuclear magnetic resonance spectroscopy. These demonstrated glass-ZIF atom-atom correlations. Additionally, carbon dioxide uptake and stability tests were also performed to check the increment of the surface area and the stability and durability of the material in different media. This opens up possibilities for creating new composites that include the intrinsic chemical properties of the constituent MOFs and inorganic glasses

Thermally activated structural phase transitions and processes in metal-organic frameworks.

Acknowledgements: C. C. B., A. M. C. and T. D. B. thank Leverhulme Trust Research Project Grant (RPG-2020-005). T. D. B. also thanks the Royal Society for both a University Research Fellowship (URF\R\211013) and a research grant (RGS\R2\212221).The structural knowledge of metal-organic frameworks is crucial to the understanding and development of new efficient materials for industrial implementation. This review classifies and discusses recent advanced literature reports on phase transitions that occur during thermal treatments on metal-organic frameworks and their characterisation. Thermally activated phase transitions and procceses are classified according to the temperaturatures at which they occur: high temperature (reversible and non-reversible) and low temperature. In addition, theoretical calculations and modelling approaches employed to better understand these structural phase transitions are also reviewed

Unravelling the local structure of catalytic Fe-oxo clusters stabilized on the MOF-808 metal organic-framework

Stabilizing catalytic iron-oxo-clusters within nanoporous metal–organic frameworks (MOFs) is a powerful strategy to prepare new active materials for the degradation of toxic chemicals, such as bisphenol A. Herein, we combine pair distribution function analysis of total X-ray scattering data and X-ray absorption spectroscopy, with computational modelling to understand the local structural nature of added redox-active iron-oxo clusters bridging neighbouring zirconia-nodes within MOF-808

Materials Formed by Combining Inorganic Glasses and Metal-Organic Frameworks.

Here, we propose the combination of glassy or crystalline metal-organic frameworks (MOFs) with inorganic glasses to create novel hybrid composites and blends.The motivation behind this new composite approach is to improve the processability issues and mechanical performance of MOFs, whilst maintaining their ubiquitous properties. Herein, the precepts of successful composite formation and pairing of MOF and glass MOFs with inorganic glasses are presented. Focus is also given to the synthetic routes to such materials and the challenges anticipated in both their production and characterisation. Depending on their chemical nature, materials are classified as crystalline MOF-glass composites and blends. Additionally, the potential properties and applications of these two classes of materials are considered, the key aim being the retention of beneficial properties of both components, whilst circumventing their respective drawbacks

Catalytic Fe-Oxo Clusters Stabilized on the MOF-808 Metal Organicframework for the Degradation of Water Pollutants

Stabilizing catalytic iron-oxo-clusters within nanoporous metal-organic frameworks (MOF) is a powerful strategy to prepare new active materials for the degradation of toxic chemicals, such as bisphenol A. Herein, we combine pair distribution function analysis of total X-ray scattering data and X-ray absorption spectroscopy, with computational modelling to understand the local structural nature of added redox-active iron-oxo clusters bridging neighbouring zirconia-nodes within MOF-808.</p

Transient intermediate in the formation of an amorphous metal-organic framework.

Acknowledgements: AFS acknowledges the EPSRC for a PhD studentship award under the industrial CASE scheme, along with Johnson Matthew PLC (JM11106). MFT acknowledges Corning Incorporated for a PhD studentship. TDB thanks the Royal Society for both a University Research Fellowship (URF\R\211013) and a research grant (RGS\R2\212221). TDB and CCB acknowledge funding from a Leverhulme Trust Research Project Grant (RPG-2020-005). We would thank Diamond Light Source for the provision of beam time at the I20-EDE beamline (Experiment Number SP28536-1). AFS would also like to thank Dr Hamish Yeung (University of Birmingham) for useful discussions regarding nucleation and MOF formation.Amorphous metal-organic frameworks are rarely formed via direct synthesis. Our limited understanding of their atomic assembly in solution prevents full exploitation of their unique structural complexity. Here, we use in situ synchrotron X-ray absorption spectroscopy with sub-second time resolution to probe the formation of the amorphous Fe-BTC framework. Using a combination of spectral fingerprinting, linear combination analysis, and principal component analysis coupled with kinetic analyses, we reveal a multi-stage formation mechanism that, crucially, proceeds via the generation of a transient intermediate species

Survival of Zirconium-Based Metal-Organic Framework Crystallinity at Extreme Pressures.

Recent research on metal-organic frameworks (MOFs) has shown a shift from considering only the crystalline high-porosity phases to exploring their amorphous counterparts. Applying pressure to a crystalline MOF is a common method of amorphization, as MOFs contain large void spaces that can collapse, reducing the accessible surface area. This can be either a desired change or indeed an unwanted side effect of the application of pressure. In either case, understanding the MOF's pressure response is extremely important. Three such MOFs with varying pore sizes (UiO-66, MOF-808, and NU-1000) were investigated using in situ high-pressure X-ray diffraction and Raman spectroscopy. Partial crystallinity was observed in all three MOFs above 10 GPa, along with some recovery of crystallinity on return to ambient conditions if the frameworks were not compressed above thresholds of 13.3, 14.2, and 12.3 GPa for UiO-66, MOF-808, and NU-1000, respectively. This threshold was marked by an unexpected increase in one or more lattice parameters with pressure in all MOFs. Comparison of compressibility between MOFs suggests penetration of the pressure-transmitting oil into MOF-808 and NU-1000. The survival of some crystallinity above 10 GPa in all of these MOFs despite their differing pore sizes and extents of oil penetration demonstrates the importance of high-pressure characterization of known structures

Principles of Melting in Hybrid Organic-Inorganic Perovskite and Polymorphic ABX3 Structures

Four novel dicyanamide-containing hybrid organic-inorganic ABX3 structures are reported, and the thermal behaviour of a series of nine perovskite and non-perovskite ABX3 structures in total are analysed. Structure-property relationships are investigated by varying both A-site organic and B-site transition metal cations. The introduction of larger tetraalkylammonium cations into the A-site reduces the melting temperature, and raises the Tolerance Factor. Total scattering methods are used to provide a greater understanding of the melting mechanism

Encoding Metal-Cation Arrangements in Metal-Organic Frameworks for Programming the Composition of Electrocatalytically Active Multi-Metal Oxides

In the present contribution, we report how through the use of metal-organic frameworks (MOFs) composed of addressable combinations of up to four different metal elements it is possible to program the composition of multi-metal oxides, which are not attainable by other synthetic methodologies. Thus, due to the ability to distribute multiple metal cations at specific locations in the MOF secondary building units it is possible to code and transfer selected metal ratios to multi-metal oxides with novel, desired compositions through a simple calcination process. The demonstration of an enhancement in the electrocatalytic activity of new oxides by pre-adjusting the metal ratios is here reported for the oxygen reduction reaction, for which activity values comparable to commercial Pt/C catalysts are reached, while showing long stability and methanol tolerance