Liquid crystals based on semiperfluorinated imines and salicylaldimato metal complexes. A comparative study of alkyl, alkoxy and polyether substituents

Three series of imines containing fluoroalkyl, polyether, alkyl and alkoxy peripheral chains have been prepared. The phase behaviour of the semiperfluorinated compounds has been investigated by optical polarizing microscopy, differential scanning calorimetry and X-ray scattering. The thermal behaviour of the semiperfluorinated imines1–10 depends on the number of chains, the substitution pattern and the number of fluorine atoms in the fluoroalkyl chains. Increasing the number of fluorine atoms in the fluoroalkyl chains leads to a stabilization of smectic and columnar mesophases. The effect of polyether side chains on the mesomorphic behaviour of imine compounds has also been investigated. In addition, first examples of mesogenic copper(II) complexes carrying semiperfluorinated alkyl chains at their peripheries and a palladium complex have been synthesized and their liquid crystalline properties have been investigated.