Terminal end‐group efficiency for the nematic phase using model bicyclo[2.2.2]octanes

Abstract

The synthesis is reported of new liquid crystals incorporating the 1,4‐disubstituted bicyclo[2.2.2]octane ring and a series of substituents in a terminal position on the molecular core. The nature of the terminal substituent is varied from apolar with a small dipole moment to polar with a strong dipole moment. The angle of the dipole moment with respect to the molecular axis is also varied. An updated order of terminal group efficiency for substituents in a terminal position for the nematic phase is provided. The bicyclo[2.2.2]octane ring shields halogen substituents in a lateral position on phenyl rings attached to the bicyclooctane ring to a small degree and reduces the steric efects of these substituents, giving rise to high relative nematic–isotropic transition temperatures.

Acknowledgements

We express our thanks to the EPSRC for funding (AL and SPK). We would also like to thank B. Worthington (¹H NMR) and K. Welham (MS) for spectroscopic measurements.