Solvent-induced high proton conductivity of a water-stable three-dimensional Mn(II) metal-organic framework

Abstract

An Mn-based MOF [Mn3(Habtc)2](guest) (1) with high proton conductivity was prepared using 3, 3′, 5, 5′-dioxybenzene-tetracarboxylic acid (H4abtc) as the ligand. Interestingly, the crystallization of 1 in water and acetonitrile carries different guest molecules, forming [Mn3(Habtc)2](H2O)8 (1A) and [Mn3(Habtc)2](CH3CN)2(H2O)5 (1B), respectively. The AC impedance test results show that, although both 1A and 1B have high proton conductivity under certain temperature and humidity conditions, the conductivity of 1B is higher than that of 1A under the same conditions. Especially at 100 °C and 98% relative humidity (RH), the conductivities of 1A and 1B are 2.55 × 10−3 and 9.02 × 10−3 S cm−1, respectively. The conductivity of 1B is more than three times that of 1A. These results indicate that guest molecules also have an important effect on the proton conductivity of MOFs. It also provides a new method for us to regulate the conductivity of MOF in the future.