Vanishing tails and a resilient mesophase: columnar liquid crystals in the limit of short tails

Abstract

Discotic liquid crystals (DLCs) are disc shaped molecules, typically with a flat rigid aromatic core functionalized with long flexible tails about the periphery. Here two series of novel triphenylene based discotic liquid crystals are synthesized using strategies including the photocyclodehydrofluorination (PCDHF) reaction, the S_NAr reaction and the Suzuki reaction. Some of these new partially fluorinated triphenylene compounds have significantly shorter tails than are usually found in DLCs. The first series comprises tetrafluorinated tetraalkoxy triphenylene compounds while the second series comprises difluorinated hexaalkoxy triphenylene compounds, with tail lengths also ranging from methoxy to hexyloxy for both series. This latter difluorinated hexaalkoxy series is directly comparable to the well-known HAT series. The tetrafluorinated compounds are of particular interest as they have retained their mesomorphic properties despite having significantly shorter tails than are typically found in DLCs, including methoxy and ethoxy tails.