Uniaxial Movements of a Metal-Cyanide Framework Switched by Weak Interactions through Dehydration and Rehydration.

A metal-cyanide framework undergoes a dehydration-rehydration triggered reversible single-crystal-to-single-crystal transformation. The resulting accordion-like contraction-expansion corresponds to a size change along the c axis as much as 24 %. This anisotropic response arises from the cooperativity among the water molecules, K ions, and CN groups between the unique two-dimensional bimetallic layers through weak interactions of hydrogen bonds and electrostatic (ionic) interactions. The key role of the water molecules in the dehydration-rehydration process is revealed by solid-state ¹H NMR spectroscopy and dielectric measurements. [ABSTRACT FROM AUTHOR]