Postsynthetic ion exchange and characterization of alkali metal ions ordered in the pores of anionic Zr metal-organic framework

Abstract

Binding alkali metal ions in solutions is an important yet difficult task and it is especially true for a solid host in aqueous systems. This study shows that a water stable, anionic metal-organic framework (Zr-dobdc) is capable of capturing M+ (M = Li, Na, K, Rb, and Cs) ions dissolved in water through ion exchange. The alkali metal ions captured at the unique cation-binding pockets of Zr-dobdc and their ordered alignments in the crystal lattice are unambiguously characterized by X-ray single-crystal and powder diffraction studies. The apparent selectivity for alkali metal ions over other metal ions is also explained.