Cooperative proton transportation based on the reversible single crystal–single crystal transformation in a highly water-stable Cu-MOF with its facile and scalable preparation

Reported here is a highly crystalline Cu-MOF (denoted as HNNU-2) synthesized via one-step method in a flask at close to room temperature. HNNU-2 not only can be prepared at scale-up, but also exhibits an excellent chemical stability, which remains its perfect framework bathed in the boiling water with pH range of 5 - 13 for one week. Based on the reversible single crystal–single crystal transformation, cooperative proton transportation reasonably explains the enormous variation of proton conductivity from 10–7 S/cm below 75 °C to 10–3 S/cm above 75 °C.