Odd–even effect on SmC* formation in chiral liquid crystal dimers

A homologues series of chiral symmetric dimer was prepared from (S)-2-(6-methoxy-2-naphthyl)propionic acid. Structural effects on the mesomorphic and physiochemical properties were investigated in terms of variation in spacer length between two mesogenic units. The mesophase textures and their corresponding transition temperatures were identified by polarised optical microscopy and DSC measurements. The prepared dimeric compounds exhibit BP, N*, SmA* and SmC*/SmB* mesophase sequence. An odd–even effect was observed in forming tilted smectic phases with various length of spacers. Compounds containing even numbers of methylene spacer form SmC* mesophase, whereas odd spacers exhibited SmB* textures. Spontaneous polarisation was measured and maximum of 33.5 nC/cm−1 was observed for BDPNP-6.