Control over Flexibility of Entangled Porous Coordination Frameworks by Molecular and Mesoscopic Chemistries

Entangled porous coordination frameworks, wherein two or more distinct frameworks are catenated over an entire crystal, are known to demonstrate unique structural flexibilities in response to the accommodation of molecules in the voids between the frameworks. In this highlight review, we introduce key functions of entangled frameworks based on two principles of their dynamic features: shearing and displacement. We further describe strategies to control the flexibilities; one is a molecular chemistry approach to functionalize frameworks by chemical modification, and the other is a mesoscopic chemistry approach to change the physical form, in particular, the crystal size.