Periodicity columnar discotics

Discotic liquids crystals (also termed columnar) are frequently composed of a central core composed of a polynuclear atomatic molecule substituted with pendant paraffin chains. Although liquids, they have crystalline order in certain directions, as shown by narrow X-ray diffraction peaks. Brown and Crooker wrote a basic discussion (99) and Hinov compiled a literature review for the period 1977-1984 (100). Other papers show the relation to polynuclear aromatics (101-110). 

The resulting mixtures revealed the existence of columnar mesophases, with a pronounced intracolumnar order, the stacking periodicity being in the range from 3.40 to 3.45 A. The same type of ordered columnar mesophase has been induced by mixing discotic nematic compounds with TNF. In this case, the interactions between the disks are too small in themselves to favour a columnar mesophase, but the incorporation of electron acceptor molecules such as TNF contributes to enhance the intermolecular interactions and to generate an ordered columnar mesophase. The stabilization of the columnar structure in these binary systems has been found for other types of molecules... 

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