Influence of Chain Rigidity

The -alkanoic acids (long-chain fatty acids) exhibit liquid crystalline characteristics. The alkane chain can be represented in an -trans structure that gives the molecules the required high aspect ratio however, being very flexible it will allow the dimer to readily form a crystalline structure. If, however, double bonds are now introduced into the structure in the form of alka-2,4-dienoic acids, the structure is now sufficiently rigid, due to restricted rotation about 

Liquid-like layers with upright alignment of molecules Two distinct t q)es of Sb have been identified  

Chiral Sc with twist axis normal to the layers Cubic 

Monoclinic (a b) with in-plane short-range positional correlation and weak or no interlayer positional correlation (titled hexatic type of structure) 

Chiral Sh, with twist axis normal to the layers 3D crystal, monoclinic b d) 

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