Saddle-shaped tetraphenylenes with peripheral gallic esters displaying columnar mesophases

Abstract

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 (C5-C8) did not show any mesomorphic properties, whereas compounds 2e-i with C 9-C13 chains displayed rectangular columnar mesophases and compounds 2j-l with C14-C16 chains displayed hexagonal columnar mesophases. Furthermore an anomalous odd-even effect of the clearing points of compounds 2e-l versus chain length was detected. © 2009 Wuckert et al; licensee Beilstein-Institut.