Transition from one-dimensional water to ferroelectric ice within a supramolecular architecture

Ferroelectric materials are characterized by spontaneous electric polarization that can be reversed by inverting an external electric field. Owing to their unique properties, ferroelectric materials have found broad applications in microelectronics, computers, and transducers. Water molecules are dipolar and thus ferroelectric alignment of water molecules is conceivable when water freezes into special forms of ice. Although the ferroelectric ice XI has been proposed to exist on Uranus, Neptune, or Pluto, evidence of a fully proton-ordered ferroelectric ice is still elusive. To date, existence of ferroelectric ice with partial ferroelectric alignment has been demonstrated only in thin films of ice grown on platinum surfaces or within microdomains of alkali-hydroxide doped ice I. Here we report a unique structure of quasi-one-dimensional (H₂O)_12n wire confined to a 3D supramolecular architecture of [Cu^I₂Cu^II(CDTA) (4,4′-bpy)₂]_n H₄CDTA, trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid; 4,4′-bpy, 4,4′-bipyridine). In stark contrast to the bulk, this 1D water wire not only exhibits enormous dielectric anomalies at approximately 175 and 277 K, respectively, but also undergoes a spontaneous transition between "1D liquid" and "1D ferroelectric ice" at approximately 277 K. Hitherto unrevealed properties of the 1D water wire will be valuable to the understanding of anomalous properties ofwater and synthesis of novel ferroelectric materials.