Odd–even effects in the phase transition behaviour of novel U‐shaped liquid crystals

Abstract

A homologous series of U‐shaped dimeric liquid crystals in which two mesogenic groups are connected via catechol has been prepared and the effects of terminal alkyl chains, alkyl spacers and core structures on the transition properties investigated by means of optical microscopy and differential scanning calorimetry. The phase sequence exhibits a pronounced odd–even effect as the length and parity of the spacers is varied, in which the even members favour the nematic and smectic C phases, whereas the odd members favour the nematic and smectic A phases. We discuss the transition behaviour of the U‐shaped compounds in terms of molecular shape.

Acknowledgement

We thank Drs Isa Nishiyama, Jun Yamamoto and Hiroshi Yokoyama of Yokoyama Nano‐structured Liquid Crystal Project for XRD measurements. This work was partially supported by Aomori Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, JST and A Grant for Priority Research Designated by the President of Hirosaki University.