Aromatic esters, chiral smectics

Recently, we also found that several types of chiral smectic C phases composed of achiral and chiral aromatic esters exhibit a large shift of their pitch band CD, depend-... 

Aromatic imide groups are known to be nearly planar, rigid, polar, and thermostable. However, aromatic imide structures are also known to be non-mesogen in nature. Poly(ester-amide) (PEI) derived from N- (4 -carboxyphenyl) trimellitimide and aliphatic spacers are not thermotropic, whether the spacer used is chiral or not. Semi-aliphatic spacers are observed to exhibit both a smectic and a nematic LC phase in the resultant thermotropic PEIs. The semi-aliphatic chiral spacers exhibit both chiral smectic phase (A or C ) and cholesteric phase. Such a chiral smectic LC-phase, which may be ferroelectric in nature, is extremely rare for LC-main-chain polymers [27]. It is a particular advantage of polar imide mesogens to favor the formation of layer-structures when combined with non-polar species [28]. 

The synthesis of the first achiral host material that exhibits a smectic Cau phase [36] (achiral version of the antiferroelectric phase) is shown in Fig. 42. It can be seen that this material has three aromatic rings and two ester groups, but in addition it has a swallow-tail unit. This unit (for no apparent reason at the moment) stabilizes the formation of smectic Cai, phases. The material like a ferroelectric host can be doped with a chiral dopant to give an antiferroelectric mixture. 

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