Phase transitions in novel disulphide‐bridged alkoxycyanobiphenyl dimers

Abstract

The synthesis, characterization and mesomorphic properties of the first examples of novel disulphide‐bridged alkoxycyanobiphenyl dimers are reported. The thermal behaviour of these mesogens was investigated by polarizing optical microscopy, differential scanning calorimetry and X‐ray diffractometry. The dimers with a shorter spacer exhibit only the nematic phase while dimers with a longer spacer display nematic as well as smectic phases. X‐ray diffraction experiments reveal the intercalated structure of the SmA phase of these dimers and the presence of short range SmA‐like order in the N phase (cybotactic nematic) of all the compounds, except the one with the shortest spacer.

Acknowledgement

We are grateful to Professor N. V. Madhusudana for helpful discussions. The authors wish to thank Ms K. N. Vasudha for technical support and the NMR Research Center, Indian Institute of Science, Bangalore for recording the NMR spectra.