We newly synthesized a metal–organic framework (MOF) Rb2(adp)[Zn2(ox)3]·3H2O (adp = adipic acid; ox2 − = oxalate), where the rubidium ions, carboxylic acid groups, and water molecules are located in an interlayer space of a two-dimensional (2-D) oxalate-bridged network. The structure of this compound was determined using single-crystal X-ray diffraction analysis. Hydrated phases of this compound were examined using thermogravimetry and water vapor adsorption measurements. Proton conductivity in this MOF was investigated by alternating current impedance measurements. Systematic comparison with previously reported isomorphous 2-D compounds A2(adp)[Zn2(ox)3]·3H2O (A = NH4 and K) showed that the difference in the ionic radii of the cations leads to a difference in activation energy of proton conductivity and that absence of NH4+ ions causes a significant decrease in proton conductivity, even though the ionic radius of Rb+ (1.52 Å) is closer to that of NH4+ (1.61 Å) than that of K+ (1.38 Å).
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry