Preparation of troponoid liquid crystals with a flexible oxymethylene linking unit

Abstract

2-Benzyloxytropones, which have a saturated oxymethylene (–CH₂O–) linking unit, show a monotropic smectic A phase while the corresponding alkoxybenzyl alkoxyphenyl ethers have poor mesogenic properties. The tropone carbonyl group acting as a dipolar lateral substituent enhances the smectic thermal stability.