Saddle-shaped tetraphenylenes with peripheral gallic esters displaying columnar mesophases.
Tetraphenylenes 2 with eight peripheral gallic esters were prepared in two steps from octamethoxytetraphenylene 1 in 19-72% yield. Investigation of the mesomorphic properties of 2 by DSC, POM and X-ray diffraction revealed that derivatives 2a-d with short alkoxy chain lengths (C(5)-C(8)) did not show any mesomorphic properties, whereas compounds 2e-i with C(9)-C(13) chains displayed rectangular columnar mesophases and compounds 2j-l with C(14)-C(16) chains displayed hexagonal columnar mesophases. Furthermore an anomalous odd-even effect of the clearing points of compounds 2e-l versus chain length was detected.
Wuckert
Eugen
E
Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Hägele
Constanze
C
Giesselmann
Frank
F
Baro
Angelika
A
Laschat
Sabine
S