I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Recently, there has been growing interest in the amorphous states of metal–organic frameworks (MOFs). Particular focus has been given to melt-quenched MOF glasses. In this work, to improve our understanding of the factors influencing melting, the thermal response of four closely related zeolitic imidazolate frameworks (ZIFs) was studied. Electron withdrawing ligands were found to lower both the melting and glass transition temperatures, providing a promising strategy for improving the processability of MOFs in the liquid state. Crucially, dense frameworks appear to be essential for melting, with their presence also initiating the melting of open pore frameworks. This opens up the rich polymorphic landscape of ZIFs to the preparation of novel MOF liquids and glasses.
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May 2020
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I15-1-X-ray Pair Distribution Function (XPDF)
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Patrick
Hirschle
,
Christian
Hirschle
,
Konstantin
Böll
,
Markus
Döblinger
,
Miriam
Höhn
,
Joshua M.
Tuffnell
,
Christopher W.
Ashling
,
David
Keen
,
Thomas D.
Bennett
,
Joachim O.
Rädler
,
Ernst
Wagner
,
Michael
Peller
,
Ulrich
Lächelt
,
Stefan
Wuttke
Diamond Proposal Number(s):
[21260]
Abstract: 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.
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Mar 2020
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I15-1-X-ray Pair Distribution Function (XPDF)
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Jingwei
Hou
,
María Laura
Ríos Gómez
,
Andraž
Krajnc
,
Aoife
Mccaul
,
Shichun
Li
,
Alice M.
Bumstead
,
Adam F.
Sapnik
,
Zeyu
Deng
,
Rijia
Lin
,
Philip A.
Chater
,
Dean S.
Keeble
,
David A.
Keen
,
Dominique
Appadoo
,
Bun
Chan
,
Vicki
Chen
,
Gregor
Mali
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Abstract: The synthesis of four novel crystalline zeolitic imidazolate framework (ZIF) structures using a mixed-ligand approach is reported. The inclusion of both imidazolate and halogenated benzimidazolate-derived linkers leads to glass-forming behavior by all four structures. Melting temperatures are observed to depend on both electronic and steric effects. Solid-state NMR and terahertz (THz)/Far-IR demonstrate the presence of a Zn-F bond for fluorinated ZIF glasses. In situ THz/Far-IR spectroscopic techniques reveal the dynamic structural properties of crystal, glass and liquid phases of the halogenated ZIFs, linking the melting behavior of ZIFs to the propensity of the ZnN4 tetrahedra to undergo thermally-induced deformation. The inclusion of halogenated ligands within MOF-glasses improves their gas uptake properties.
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Jan 2020
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E02-JEM ARM 300CF
I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[20038, 20195]
Abstract: 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.
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Sep 2019
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E02-JEM ARM 300CF
I15-1-X-ray Pair Distribution Function (XPDF)
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Jingwei
Hou
,
Christopher W.
Ashling
,
Sean M.
Collins
,
Andraž
Krajnc
,
Chao
Zhou
,
Louis
Longley
,
Duncan N.
Johnstone
,
Philip
Chater
,
Shichun
Li
,
Marie-vanessa
Coulet
,
Philip L.
Llewellyn
,
François-xavier
Coudert
,
David
Keen
,
Paul A.
Midgley
,
Gregor
Mali
,
Vicki
Chen
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[171151, 19130, 16983]
Open Access
Abstract: 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.
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Jun 2019
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I15-1-X-ray Pair Distribution Function (XPDF)
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Jiayang
Zhang
,
Louis
Longley
,
Hao
Liu
,
Christopher W.
Ashling
,
Philip A.
Chater
,
Kevin A.
Beyer
,
Karena W.
Chapman
,
Haizheng
Tao
,
David A.
Keen
,
Thomas D.
Bennett
,
Yuanzheng
Yue
Diamond Proposal Number(s):
[171151]
Abstract: A pronounced enthalpy release occurs around 1.38 Tg in the prototypical metal-organic framework glass formed from ZIF-4 [Zn(C3H3N2)2], but there is no sign for any crystallization (i.e., long-range ordering) taking place. This behavior is in strong contrast to that for other families of melt-quenched glasses.
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Feb 2019
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I22-Small angle scattering & Diffraction
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Louis
Longley
,
Sean M.
Collins
,
Shichun
Li
,
Glen J.
Smales
,
Ilknur
Erucar
,
Ang
Qiao
,
Jingwei
Hou
,
Cara M.
Doherty
,
Aaron W.
Thornton
,
Anita J.
Hill
,
Xiao
Yu
,
Nicholas J.
Terrill
,
Andrew J.
Smith
,
Seth M.
Cohen
,
Paul A.
Midgley
,
David A.
Keen
,
Shane G.
Telfer
,
Thomas
Bennett
Diamond Proposal Number(s):
[18236]
Open Access
Abstract: Recent demonstrations of melting in the metal–organic framework (MOF) family have created interest in the interfacial domain between inorganic glasses and amorphous organic polymers. The chemical and physical behaviour of porous hybrid liquids and glasses is of particular interest, though opportunities are limited by the inaccessible melting temperatures of many MOFs. Here, we show that the processing technique of flux melting, ‘borrowed’ from the inorganic domain, may be applied in order to melt ZIF-8, a material which does not possess an accessible liquid state in the pure form. Effectively, we employ the high-temperature liquid state of one MOF as a solvent for a secondary, non-melting MOF component. Differential scanning calorimetry, small- and wide-angle X-ray scattering, electron microscopy and X-ray total scattering techniques are used to show the flux melting of the crystalline component within the liquid. Gas adsorption and positron annihilation lifetime spectroscopy measurements show that this results in enhanced, accessible porosity to a range of guest molecules in the resultant flux melted MOF glass.
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Feb 2019
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I15-1-X-ray Pair Distribution Function (XPDF)
I22-Small angle scattering & Diffraction
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Chao
Zhou
,
Louis
Longley
,
Andraž
Krajnc
,
Glen J.
Smales
,
Ang
Qiao
,
Ilknur
Erucar
,
Cara M.
Doherty
,
Aaron W.
Thornton
,
Anita J.
Hill
,
Christopher W.
Ashling
,
Omid T.
Qazvini
,
Seok J.
Lee
,
Philip A.
Chater
,
Nicholas J.
Terrill
,
Andrew J.
Smith
,
Yuanzheng
Yue
,
Gregor
Mali
,
David A.
Keen
,
Shane G.
Telfer
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[18236]
Open Access
Abstract: To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently and reversibly porous toward incoming gases, without post-synthetic treatment. We characterize the structure of these glasses using a range of experimental techniques, and demonstrate pores in the range of 4 – 8 Å. The discovery of MOF glasses with permanent accessible porosity reveals a new category of porous glass materials that are elevated beyond conventional inorganic and organic porous glasses by their diversity and tunability.
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Nov 2018
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[171151]
Abstract: In this work, we explore the thermodynamic evolution in a melt-quenched metal–organic framework glass, formed from ZIF-62 upon heating to the melting point (Tm), and subsequent enthalpy relaxation. The temperature dependence of the difference in Gibbs free energy between the liquid and crystal states of ZIF-62 in the temperature range from the glass transition temperature (Tg) to Tm is found to be weaker than those of other types of glasses, e.g., metallic glasses. Additionally, we find that the stretched exponent of the enthalpy relaxation function in the glass varies significantly (β = 0.44–0.76) upon changing the extent of sub-Tg annealing, compared to metallic and oxide glasses with similar Tgs, suggesting a high degree of structural heterogeneity. Pair distribution function results suggest no significant structural changes during the sub-Tg relaxation in ZIF-62 glass.
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Jun 2018
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I15-1-X-ray Pair Distribution Function (XPDF)
I22-Small angle scattering & Diffraction
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Louis
Longley
,
Sean
Collins
,
Chao
Zhou
,
Glen J.
Smales
,
Sarah E.
Norman
,
Nick J.
Brownbill
,
Christopher W.
Ashling
,
Philip A.
Chater
,
Robert
Tovey
,
Carola-bibiane
Schönlieb
,
Thomas F.
Headen
,
Nicholas J.
Terrill
,
Yuanzheng
Yue
,
Andrew J.
Smith
,
Frédéric
Blanc
,
David
Keen
,
Paul A.
Midgley
,
Thomas
Bennett
Diamond Proposal Number(s):
[171151, 18236]
Open Access
Abstract: 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.
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Jun 2018
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