Dielectric Properties of Porous Molecular Crystals That Contain Polar Molecules

Simply lowering the temperature changes a polarizable molecular system, which consists of H2O and CH3OH inserted into the porous crystal Mn3(HCOO)6 (see structure; Mn pink, C gray, O red), into a nonpolarizable one. Although a large drop in the dielectric constant was observed around 120 K, reminiscent of a liquid↔solid phase transition of the guest molecules, the anisotropy cannot be explained by a simple liquid model of the guest molecules.