Basic molecular structure of rodic liquid crystals

Basic molecular structure of rodic liquid crystals 

The basic structure of low molecular mass liquid crystals or monomers of liquid crystalline polymers is schematically shown below 

The terminal group primarily contributes to the dielectric anisotropy and the refractive indices, which in turn affects the threshold voltage and optical properties in display applications, respectively. Common terminal groups are alkyl, alkoxy, cyano, nitro, isocyanate (NCS), sulfide and halides such as F, Cl, CF3 and OCF3. 

Most liquid crystal compounds consist of two or more aromatic rings. Those aromatic rings can be a totally saturated cyclohexane, a cyclocyclohexane, an unsaturated biphenyl, terphenyl, or combinations of them. Usually, the longer the ring, the higher the melting temperature. 

The linking group makes an important contribution to the phase transition and physical properties such as the birefringence. The following linking groups have been well studied 

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