Synthesis and mesomorphism of fluoroalkylated organometallic mesogens

Abstract

The first examples of liquid crystalline chloro-bridged dinuclear palladium organyls carrying semiperfluorinated alkyl chains at their peripheries have been synthesised. The liquid crystalline properties were investigated using polarised optical microscopy, differential scanning calorimetry and X-ray scattering. Compounds with six semifluorinated chains and two alkyl chains show hexagonal columnar liquid-crystalline phases with dramatically enhanced mesophase stabilities compared to the related hydrocarbon derivatives, which have only monotropic discotic nematic phases. Compounds with only four semifluorinated alkyl chains and two alkyl chains exhibit enantiotropic smectic A and monotropic smectic C mesophases. Preliminary experiments with mixed systems (eight-chain compounds and six-chain compounds, as well as binary systems with dodecane or TNF) were also carried out.