THE EFFECT OF MOLECULAR CHIRALITY ON THE INCIDENCE OF TWISTED SMECTIC-A PHASES

Four chiral chloro-esters were synthesized in order to examine systematically the effect that molecular chirality has on the temperature range and incidence of the twisted smectic A phase or the twist grain boundary phase as it has become known. We find that when the motion of the chiral centre is restricted by rotational hindrance, thereby increasing the chirality of the system, the twisted S(A) phase range is increased. At low chirality the twisted S(A) phase disappears altogether. Furthermore, it is shown that the transition temperatures of the chiral compounds are lower than their racemic analogues.