Asymmetry in liquid crystalline hexaalkoxytriphenylene discotics

The synthesis and phase behaviour of a new series of unsymmetrically substituted hexaalkoxytriphenylene¿based liquid crystals are reported. One of the hexyloxy chains in hexahexyloxytriphenylene (HAT6) is replaced by either a shorter or a longer chain, HAT¿(OC 6 H 13 ) 5 (OC n H 2 n +1 ). Compounds with chain lengths n of 2¿14, 16 and 18 were prepared and investigated. Compounds with n ¿13 were not liquid crystalline. For all compounds with n ¿12 Col h textures were observed by polarizing microscopy. X¿ray investigations showed that the intercolumnar distance gradually increased with n from n = 2 to n = 12, while the interdisk distance (3.6 Å) remained constant. A small odd¿even effect on the increase of the intercolumn distance with n was observed. This effect was also found in the change of ¿ H of isotropization with