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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. 

Abstract Non‐porous small molecule adsorbents such as {[3,5‐(CF₃)₂Pz]Cu}₃(where Pz=pyrazolate) are an emerging class of materials that display attractive features for ethene−ethane separation. This work examines the chemistry of fluorinated copper(I) pyrazolates {[3,5‐(CF₃)₂Pz]Cu}₃and {[4‐Br‐3,5‐(CF₃)₂Pz]Cu}₃with much larger 1‐butene in both solution and solid state, and reports the isolation of rare 1‐butene complexes of copper(I), {[3,5‐(CF₃)₂Pz]Cu(H₂C=CHC₂H₅)}₂and {[4‐Br‐3,5‐(CF₃)₂Pz]Cu(H₂C=CHC₂H₅)}₂and their structural, spectroscopic, and computational data. The copper−butene adduct formation in solution involves olefin‐induced structural transformation of trinuclear copper(I) pyrazolates to dinuclear mixed‐ligand systems. Remarkably, larger 1‐butene is able to penetrate the dense solid material and to coordinate with copper(I) ions at high molar occupancy. A comparison to analogous ethene and propene complexes of copper(I) is also provided.