Rationally tuning host-guest interactions to free hydroxide ions within intertrimerically cuprophilic metal-organic frameworks for high OH− conductivityElectronic supplementary information (ESI) available. CCDC 1475870-1475872. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6ta11242k

Hydroxide-anion-exchange membrane fuel cells (HEMFCs) are now considered as one of the most promising green energy-conversion technologies for stationary and mobile applications, showing high fuel conversion efficiency at high pH and low cost due to their ability to operate under basic conditions using non-precious metal catalysts. But one key impediment to commercialization is insufficient hydroxide ion (OH − ) conductivity of the central HEM component. Here, we report the development of free OH − anion-containing metal-organic frameworks (FOMOFs) with rationally tunable host-guest interactions for HEMs with high OH − conductivity. Among three solids obtained by post-synthesis treatment of ultrastable MOF FJU-66 with various bases, free OH − anions are observed in FJU-66·[EVIm]OH with strong host-guest interactions between the MOF backbone and guest cations. Despite the lowest OH − concentration, FJU-66·[EVIm]OH exhibits the highest OH − conductivity close to 0.1 S cm −1 . The high OH − conductivity achieved suggests the potential application of the FOMOFs for practical HEMs of fuel cells. Rationally tuning host-guest interactions to free hydroxide ions within intertrimerically cuprophilic MOF for high OH − conductivity.