A drastic change in the superhydrophilic crystal porosities of metallosupramolecular structures via a slight change in pH.

A unique pH-controlled synthesis of two metallosupramolecular structures from CoAu complex anions and ZnII cations is reported. A dense coordination polymer (porosity ∼13%) was formed at a pH of 5.0, whereas a porous ionic framework (porosity ∼61%) that selectively adsorbs CO2 and H2O was created when the pH was adjusted to 5.5.