Mesomorphic properties of lactic acid derivatives and their racemic mixtures in comparison with analogous non-chiral compounds

We have synthesised a series of lactic acid derivatives and studied their mesomorphic properties. Studied compounds consist of a molecular core laterally substituted by a chlorine atom, and we modified both terminal chains. We concentrated on the effect of the terminal alkyl chain length in the chiral part. For selected homologues, both enantiomers were prepared and mixed in racemic mixtures. We studied the mesomorphic behaviour and for one homologue a reentrancy of the SmA phase below the tilted SmC phase was detected, for both chiral enantiomers and for the racemic mixture. For chiral compounds with the SmC* phase, ferroelectric properties were studied by dielectric spectroscopy and switching properties were described. Reentrancy of the SmA phase was experimentally proved by several experimental techniques including x-ray measurements. For racemic mixtures and non-chiral analogues, we reached a good alignment, which allowed us to measure the birefringence and analyse the behaviour at the phase transitions.