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. (Figure Presented). © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.