Crystal melting and glass formation in copper thiocyanate based coordination polymersElectronic supplementary information (ESI) available: Experimental details, crystallographic data, XRPD, DSC, IR, and NMR. Crystallographic data for the compounds in CIF format with CCDC 1899561-1899564. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c9cc02172h

Crystal melting and glass formation of coordination polymers (CPs) and metal-organic frameworks (MOFs) are rare thermal events. To expand the library of melting CP/MOFs, we utilized anti-crystal engineering in ionic liquids to construct CPs. A combination of Cu + and 4,4′-bipyridin-1-ium derivatives afforded four melting CPs showing stable liquid and glassy states. The melting point of Cu + coordination polymer crystals is controlled by ligands, and the reversible crystal-to-glass state is observed.