Phenylpyrimidine cores

J.R. Bruckner, D. Krueerke, J.H. Porada, S. Jagiella, D. Blunk and F. Giesselmann, The 2D-correlated structures of a lyotropic liquid crystalline diol with a phenylpyrimidine core. J Mater Chem 22, 18198-18203 (2012)... 

The use of two long terminal chains in the phenylpyrimidine core generates the phase... 

Compound 15 uses a polar cyano group at a chiral centre which is part of a ring stracture and very close to the aromatic core. Accordingly, the combination of polarity and restricted rotation should ensure a high Pg. As a 10% component in a phenylpyrimidine... 

Materials with multiaiyl cores e.g., biphenyls, terphenyls and phenylpyrimidines) and esters that include biphenol or bipheitylcarboxylic acid moieties are somewhat more difficult to prepare because of the direct bond between the aiyl sections. Traditionally, the biphenyl liquid crystals are prepared by the modification of bipheityl in a linear fashion as distinct from a convergent approach. For example, a synthesis of 4-cyano-4 -pentylbiphenyl (28) from biphei rl (24) is shown in Scheme 6. Liquid crystals require a long, linear architecture and hence most simple structures are 4,4 -disubstituted. Fortunately, such linear syntheses work fairly well but overall yields are considerably reduced as the number of steps increases. 

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