Classification of Chiral Nematic Liquid Crystalline Compounds

3 ClassiHcation of Chiral Nematic Liquid Crystalline Compounds 

Despite the wide variety of chiral nematic liquid crystals (and of course low molar mass chiral liquid crystals in general), it is possible to sub-divide them into three class types, according to the relationship of the chiral moiety and the liquid-erystalline core [29]. Firstly, we consider type I here the chiral centre (or multiplieity of chiral centres) is situated in a terminal alkyl chain attached to the effective liquid-crystalline core. As will be seen later, it is entirely possible that the compound can have two or more chiral terminal groups associated with the molecule. Type I materials are probably the most frequently encountered chiral nematic liquid-crystalline compounds, often 

Type I terminal chiral chains appended to a liquid-crystalhne core 

Type II flexible chiral spacer chain between two liquid-crystalline cores 

Type ID chiral point or structural molecular asymmetry within the liquid-crystalline core 

---