Melt-Quenched Glasses of Metal–Organic Frameworks

Thomas D. Bennett, Yuanzheng Yue, Peng Li, Ang Qiao, Haizheng Tao, Neville G. Greaves, Tom Richards, Giulio I. Lampronti, Simon A. T. Redfern, Frédéric Blanc, Omar K. Farha, Joseph T. Hupp, Anthony K. Cheetham, David A. Keen

Crystalline solids dominate the field of metal-organic frameworks (MOFs), with access to the liquid and glass states of matter usually prohibited by relatively low temperatures of thermal decomposition. In this work, we give due consideration to framework chemistry and topology to expand the phenomenon of the melting of three-dimensional MOFs, linking crystal chemistry to framework melting temperature and kinetic fragility of the glass-forming liquids. Here we show that melting temperatures can be lowered by altering the chemistry of the crystalline MOF state, which provides a route to facilitate the melting of other MOFs. The glasses formed upon vitrification are chemically and structurally distinct from the three other existing categories of melt-quenched glasses (inorganic non-metallic, organic and metallic), and retain the basic metal-ligand connectivity of crystalline MOFs, which connects their mechanical properties to starting chemical composition. The transfer of functionality from crystal to glass points towards new routes to tunable, functional hybrid glasses.