Construction of Water-Stable Rare-Earth Organic Frameworks with Ambient High Proton Conductivity Based on Zirconium Sandwiched Heteropolytungstate

Water-stable proton-conducting materials owning excellent performances at ambient temperatures are currently one of the crucial challenges. Herein, four water stable three-dimensional polyoxometalate-based rare-earth organic frameworks have been successfully synthesized and formulated as H{Ln(4)(L)(2)(H2O)(21)[Zr-3(OH)(3)(PW9O34)(2)]}center dot 15H(2)O (1-3) (Ln = La (1), Ce (2), Pr (3); L = 3,5-pyridine dicarboxylic acid), which are the first examples of MOFs constructed by a zirconium sandwiched polyoxoanion. There are abundant coordinated water molecules functionalizing the Pr-III centers, and simultaneously, plenty of lattice water molecules are fitted into the channel of the framework. A continuous H-bonding network is found between the architectures and plays an important role in stabilizing the structure. Benefiting from the consecutive H bonding networks, compounds 1-3 showed high proton conductivities at ambient temperature (up to 1.05 x 10(-3) S.cm(-1) under 98% RH) by a synergistic effect of the combined components.

Automated summary

The newly synthesized rare-earth organic frameworks exhibit excellent water stability and high proton conductivity, making them promising candidates for proton conducting materials at ambient temperatures.