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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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Isomer‐Dependent Melting Behavior of Low Molar Mass Azobenzene Derivatives: Observation of a Higher Melting Z‐Isomer
Azobenezene compounds are putative solar thermal fuels (STF) due to excellent photostability and structural control of isomerization rates. Azobenzenes in which both Z‐ and E‐isomers are liquid at room temperature are promising candidates for STF flow technology. A literature survey of melting points led to the synthesis and isomer separation of ortho‐ and meta‐substituted, monofunctional azobenzenes with fluoro, methyl, ethyl, trifluoromethyl and methoxy substituents. Four of the compounds are liquid azobenzenes with higher energy density than literature work with higher molar mass, liquid compounds. Eight of the compounds unexpectedly displayed a higher melting point for the Z‐isomer which is rarely observed. The higher‐melting behavior is explained, in part, by intermolecular close contacts in the Z‐isomer packing lattice.
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- PAR ID:
- 10509580
- Publisher / Repository:
- ChemPhotoChem
- Date Published:
- Journal Name:
- ChemPhotoChem
- ISSN:
- 2367-0932
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/cptc.202400084
