Ferroelectric Switchable Behavior through Fast Reversible De/adsorption of Water Spirals in a Chiral 3D Metal–Organic Framework

A polar homochiral 3D MOF [{Co2(L)­(bpe)­(H2O)}·5H2O]n constructed with cobalt­(II) and a new ligand N-(1,3-dicarboxy-5-benzyl)-carboxymethylglycine (H4L) accommodates ordered helical water streams in its helical grooves. It provides the first example of switchable ferroelectric and optical behavior through two-step reversible single-crystal to single-crystal transformation (SCSC) upon desorption/adsorption of water spirals and coordinated water molecules, respectively.