Shaping solid-state supramolecular cavities: Chemically induced accordionlike movement of ?-zirconium phosphate containing polyethylenoxide pillars

The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in 7-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the 7 layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space.