Metal-Organic Framework Crystal-Glass Composites

Abstract

The majority of research into metal-organic frameworks (MOFs) focuses on their crystalline nature. However, in recent research the vitrification of a number of MOFs has been revealed. We propose that the solid-liquid phase transitions involved in MOF-glass formation can provide unique opportunities for the creation of a new class of functional, stable and porous composite materials. Described herein is the design, synthesis, and characterisation of novel metal-organic framework (MOF) crystal-glass composites, formed by dispersing crystalline MOFs within a MOF-glass matrix. We demonstrate using structural characterisation and analytical electron tomography, that the coordinative bonding and chemical structure of a MIL-53 crystalline phase are preserved within the ZIF-62 glass matrix. Whilst separated phases, the microdomains of each lie close to one another and possess interfacial interactions which improve the mechanical properties of the composite glass. More significantly, the high temperature open pore phase of MIL-53, which spontaneously transforms to a narrow pore upon cooling, is stabilized at room temperature in the crystal-glass composite. This leads to a significantly higher gas adsorption capacity for the crystal-glass composite than for either constituent phase.

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

“…Wehmeyer et al (2018) used virtual apertures to measure thermal diffuse scattering between Bragg disks as a measurement of local temperature. Tao et al (2016) used 4D-STEM to study electronic liquid–crystal phase transitions and their microscopic origin, and Hou et al (2018) used it to measure the degree of crystallinity in metal–organic-frameworks (MOFs). We expect that as pixelated detectors fall in price and larger amounts of computational power are available at the microscope, virtual imaging will become a very common operating mode for 4D-STEM.…”

Ameliorative effect of a nano chromium metal–organic framework on experimental diabetic chronic kidney disease

“…MOFs important structural characteristics are well‐developed porosity, high surface area and crystallinity. Many practical applications of MOFs are the outcomes of these structural features (Dabla, 2010; Hou et al, 2019; Ji et al, 2018). Likewise, DIFc enjoys high porosity and special crystalline structure demonstrated in BET analysis and XRD graph, respectively.…”

Functional Group Mapping by Electron Beam Vibrational Spectroscopy from Nanoscale Volumes

“…Characterization approaches that analyze the full sample volume, such as nuclear magnetic resonance (NMR) spectroscopy techniques, have been successfully demonstrated to describe the typical coordination features preserved in MOFs and MOF composites. 19 However, these 'ensemble' measurements miss finescale details at individual interfaces in the material in favor of a description of the average properties. For Co-based ZIFs, optical signatures of tetrahedral coordination in the glass phase have been demonstrated using STEM-EELS, but this type of valence EELS depends on a particular, known optical signature for Co d-d transitions.…”