Flexibility control of two-dimensional coordination polymers by crystal morphology: Water adsorption and thermal expansion.

Layer flexibility in two-dimensional coordination polymers (2D-CPs) contributes to several functional materials as results in anisotropic structural response to external stimuli. Chemical modification is a common technique for modifying layer structures. Herein, we demonstrate that crystal morphology of a cyanide-bridged 2D-CP of type [Mn(salen)] 2 [ReN(CN) 4 ] ( 1 ) consisting of flexible undulating layers significantly impacts the layer configuration and assembly. Nanoplates of 1 showed an in-plane contraction of layers with a longer interlayer distance compared to the micrometer-sized rod-type particles. These effects by crystal morphology on the structure of the 2D-CP impacted the structural flexibility, resulting in dual-functional changes: the enhancement of the sensitivity of structural transformation to water adsorption and modification of anisotropic thermal expansion of 1 . Moreover, the nanoplates incorporated new adsorption sites within the layers, resulting in the uptake of an additional water molecule compared to the micrometer-sized rods.