Variety of mesophase behavior and crystal structures of chiral dephenylpyrimidine isomers

Abstract

In order to make clear the origin of chiral interactions responsible for an isotropic mesophase (IsoX) of a dichiral mesogen, 2-[4-[(R)-2-fiuorohexyloxy]phenyl]-5-[4-[(S)-2-fluoro-2-methyldecanoy- Ioxy]phenyl]pyrimidine (I), crystal structures have been determined for I and its isomers (II and III) without IsoX. According to the different positions of N atoms in the cores, crystal structures are quite different each other: one-dimensional chains of CH^<…>N close contacts resulting in the large overlapping of core moieties and hence, stereo-specific F-methyl interactions (I), an MHPOBC-like arrangement of bent molecules (II), and a stack of layers composed of parallel molecules (Ill).