Design, Synthesis, and Characterisation of Metal–Organic Framework Crystal–Glass Composites (MOF CGCs)

Metal–organic frameworks (MOFs) are a highly topical class of three-dimensional porous materials proposed for applications such as gas storage, separations, and catalysis. Typically, MOFs are synthesised as microcrystalline powders of nanometer- to millimetre-sized particles ill-suited to industrial settings without prior processing. However, recent research has revealed solid-liquid transitions within the family, which is used here to create a class of functional, stable and porous composite materials. Described herein is the design, synthesis and characterisation of MOF crystal–glass composites formed by dispersing crystalline MOFs within a MOF glass matrix. The first of these novel materials incorporates MIL 53 within a ZIF 62 glass matrix where the crystalline phase’s coordinative bonding and chemical structure are preserved. Whilst the phases are separated, the interfacial interactions between the proximate microdomains improve the mechanical properties of the glass composite. More significantly, the high-temperature, open-pore phase of MIL 53, which spontaneously transforms to a narrow pore phase upon cooling in the presence of water, is stabilised at room temperature in the crystal–glass composite. This leads to a significant improvement in CO2 adsorption capacity. This enhancement is further explored and maximised by synthesising a compositional series of composites. The distribution and integrity of the crystalline component in this series were determined, and these findings were used to identify the maximum crystalline loading and maximum CO2 adsorption capacity. In addition to the study of MIL 53, other MOF crystal-glass composite (MOF CGC) systems were explored, and the thermal stability considerations in the formation of MOF CGCs are highlighted. Resultantly, two separate MOFs were identified, MIL 118 and UL MOF 1, with which MOF CGCs were successfully synthesised. These new materials, alongside the prototypical MOF CGC, formed using MIL 53, were studied using scanning electron microscopy, powder X-ray diffraction, and gas sorption techniques to reveal an approximate kinetic diameter limitation of gases that may permeate through the glass matrix. Furthermore, the thermal expansion behaviour of these three MOF CGCs was investigated. Specifically, variable-temperature powder X-ray diffraction data and thermomechanical analysis show the suppression of thermal expansivity in each of these three crystalline MOFs when suspended within a ZIF 62 glass matrix. In particular, for the two flexible frameworks, the average volumetric thermal expansion (αV) was found to be near-zero in the crystal–glass composite.Royal Society (RG160498) Commonwealth Scientific and Industrial Research Council (CSIRO) (C2017/3108

Synthesis and Properties of a Compositional Series of MIL-53(Al) Metal-Organic Framework Crystal-Glass Composites

Metal-organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high-temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy. An upper limit of MIL-53(Al) that can be stabilized in the composite was determined for the first time. The nanostructure of the composites was probed using pair distribution function analysis and scanning transmission electron microscopy. Notably, the distribution and integrity of the crystalline compo-nent in a sample series was determined, and these findings related to the MOF-CGC gas adsorption capacity in order to identify the optimal loading necessary for maximum CO2 sorption capacity.TDB would like to thank both the Royal Society for a University Research Fellowship (UF150021) and the Royal Society for a Research Grant (RG94426). CWA would like to thank the Royal Society for a PhD studentship (RG160498), and the Commonwealth Scientific and Industrial Research Council for additional support (C2017/3108). Both JH and TDB gratefully acknowledge the EPSRC (EP/R015481/1). AFS acknowledges EPSRC for a studentship award under the Doctoral Training Programme. AMB acknowledges the Royal Society for funding (RGF\EA\180092), as well as the Cambridge Trust for a Vice Chancellor’s Award (304253100). We extend our gratitude to Diamond Light Source, Rutherford Appleton Laboratory, UK, for access to Beamline I15-1 (EE20038-1) and access and support in the use of the electron Physical Science Imaging Centre (EM20195). SMC acknowledges the Henslow Research Fellowship at Girton College, Cambridge. PAM thanks the EPSRC for financial support under grant number EP/R025517/1

Functional group mapping by electron beam vibrational spectroscopy from nanoscale volumes

Vibrational spectroscopies directly record details of bonding in materials, but spatially resolved methods have been limited to surface techniques for mapping functional groups at the nanoscale. Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope presents a route to functional group analysis from nanoscale volumes using transmitted subnanometer electron probes. Here, we now use vibrational EELS to map distinct carboxylate and imidazolate linkers in a metal–organic framework (MOF) crystal–glass composite material. Domains <100 nm in size are observed using vibrational EELS, with recorded spatial resolution <15 nm at interfaces in the composite. This nanoscale functional group mapping is confirmed by correlated EELS at core ionization edges as well as X-ray energy dispersive spectroscopy for elemental mapping of the metal centers of the two constituent MOFs. These results present a complete nanoscale analysis of the building blocks of the MOF composite and establish spatially resolved functional group analysis using electron beam spectroscopy for crystalline and amorphous organic and metal–organic solids

The Gift:Transforming Lives through Organ Donation

It is my great pleasure to introduce this comic. Our project originated from an honest conversation with my friend and colleague Prof Chris Murray: how to communicate complex issues surrounding the issue of organ donation? Over the last seven years I have had the honour of being an ambassador for the Organ Donation campaign by telling my son, Andrew’s, story.Through my role as an Organ Donation ambassador I meet courageous and selfless people. Some are in desperate need of hope, some are in the position to provide hope, and those who, through their professionalism and dedication, transform lives.Our sincere thanks for the support of the following organisations: University of Dundee; the NHS Blood and Transplant Specialist Nurses in Organ Donation; Dundee Comics Creative Space; Good Life, Good Death, Good Grief, and the Organ Donation Comics team. it is only through their support that this projectcame to fruition.In the following pages we share heartfelt stories and life experiences related to organ donation. By doing so we hope to bring awareness to a wider audience and prompt honest conversations about organ donation.Finally, I would like thank my sons Andrew and Stuart for warming my heart. Through tears and laughter we present to you… The Gift

Metal-organic framework crystal-glass composites.

The majority of research into metal-organic frameworks (MOFs) focuses on their crystalline nature. Recent research has revealed solid-liquid transitions within the family, which we use here to create a class of functional, stable and porous composite materials. Described herein is the design, synthesis, and characterisation of MOF crystal-glass composites, formed by dispersing crystalline MOFs within a MOF-glass matrix. The coordinative bonding and chemical structure of a MIL-53 crystalline phase are preserved within the ZIF-62 glass matrix. Whilst separated phases, the interfacial interactions between the closely contacted microdomains 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 in the presence of water, is stabilised at room temperature in the crystal-glass composite. This leads to a significant improvement of CO2 adsorption capacity

Liquid phase blending of metal-organic frameworks.

The liquid and glass states of metal-organic frameworks (MOFs) have recently become of interest due to the potential for liquid-phase separations and ion transport, alongside the fundamental nature of the latter as a new, fourth category of melt-quenched glass. Here we show that the MOF liquid state can be blended with another MOF component, resulting in a domain structured MOF glass with a single, tailorable glass transition. Intra-domain connectivity and short range order is confirmed by nuclear magnetic resonance spectroscopy and pair distribution function measurements. The interfacial binding between MOF domains in the glass state is evidenced by electron tomography, and the relationship between domain size and Tg investigated. Nanoindentation experiments are also performed to place this new class of MOF materials into context with organic blends and inorganic alloys

Tuning the Morphological Appearance of Iron(III) Fumarate: Impact on Material Characteristics and Biocompatibility

Iron(III) fumarate materials are well suited for biomedical applications as they feature biocompatible building blocks, porosity, chemical functionalizability, and magnetic resonance imaging (MRI) activity. The synthesis of these materials however is difficult to control, and it has been challenging to produce monodisperse particle sizes and morphologies that are required in medical use. Here, we report the optimization of iron(III) fumarate nano- and microparticle synthesis by surfactant-free methods, including room temperature, solvothermal, microwave, and microfluidic conditions. Four variants of iron(III) fumarate with distinct morphologies were isolated and are characterized in detail. Structural characterization shows that all iron(III) fumarate variants exhibit the metal–organic framework (MOF) structure of MIL-88A. Nanoparticles with a diameter of 50 nm were produced, which contain crystalline areas not exceeding 5 nm. Solvent-dependent swelling of the crystalline particles was monitored using in situ X-ray diffraction. Cytotoxicity experiments showed that all iron(III) fumarate variants feature adequate biotolerability and no distinct interference with cellular metabolism at low concentrations. Magnetic resonance relaxivity studies using clinical MRI equipment, on the other hand, proved that the MRI contrast characteristics depend on particle size and morphology. All in all, this study demonstrates the possibility of tuning the morphological appearance of iron(III) fumarate particles and illustrates the importance of optimizing synthesis conditions for the development of new biomedical materials

Thermal Expansion of Metal–Organic Framework Crystal–Glass Composites

Metal-organic framework crystal-glass composites (MOF CGCs) are a class of materials comprising a crystalline framework embedded within a MOF glass matrix. Here, we investigate the thermal expansion behavior of three MOF CGCs, incorporating two flexible (MIL-53(Al) and MIL-118) and one rigid (UL-MOF-1) MOF within a ZIF-62 glass matrix. Specifically, variable-temperature powder X-ray diffraction data and thermo-mechanical analysis show the suppression of thermal expansivity in each of these three crystalline MOFs when suspended within a ZIF-62 glass matrix. In particular, for the two flexible frameworks, the average volumetric thermal expansion (β) was found to be near-zero in the crystal-glass composite. These results provide a route to engineering thermal expansivity in stimuli-responsive MOF glass composites