Columnar mesophases flat discotics

Typical mesophases formed by disldike molecules are columnar, wherein the molecules are stacked into columns. The columns are in turn packed together to form two-dimensional arrays. In addition to the columnar arrangements, the molecules can become ordered in a way that is comparable to a heap of coins spread on a flat surface— the discotic nematic phase. 

Discotics are flat disclike mesogens consisting of a core of adjacent aromatic rings. This allows for mesophases based on columnar ordering (see next section). 

The first examples of thermotropic mesomorphism in discotic compounds were observed in the hexa-alkanoyloxy benzenes (1, R = C H2 +i) [1] and the hexa-alkoxy-and hexa-alkanoyloxytriphenylenes (2, R=C H2 +iO and C H2 +iCO O) [2, 3], and it was established by X-ray studies [ 1, 7] that the mesophases of these compounds have a columnar structure. About 1500 discotic mesogens are known to date [8] and a variety of new mesophase structures has been identified. The simplest of these compounds have flat or nearly flat cores surrounded by six or eight, or sometimes four,... 

Two basic types of discotic mesophases have been widely recognized these are columnar and nematic. In general, discotic liquid crystals consist of flat and rigid aromatic cores surrounded by six or eight flexible chains. These flexible chains are coimected to the core by different linking imits, such as ether, ester, benzoate, alkyne, etc (Kumar 2010). 

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