Electron acceptor molecules, columnar nematics

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... 

TABLE 4 Transition temperatures ( C, DSC data) of intermolecular donor-acceptor complexes formed spontaneously when heating equimolar mixtures of electron donor molecules (e.g. radial pentaynes of type 3b, R = H, not liquid crystalline, or the 2,3,6,7,10,11-triphenylene hexaether 4) and the non-liquid crystalline multi(nitro)fluorenone derivatives 5a, 5b or 5c as electron acceptors yielding preferably by induction the nematic or chiral nematic columnar (Ncoi or N coh respectively) phases. 

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