New 1,3-dioxane type ionic liquid crystal materials having a terminal double bond

Abstract

New 1,3-dioxane type ionic liquid crystal materials having a terminal double bond were synthesized. The mesomorphic behaviour of these compounds was measured. The principal features of these compounds are a smectic A phase over a very wide range including room temperature, and a low isotropic to mesophase transition temperature (for example, compound 6-1: Cr-22 SmA 25 I ).

Ionic Liquid Crystals

“…It was found that compounds with a terminal double bond in the alkyl chain have a lower clearing point than molecules which do not have this structural feature. 181,180 This is in agreement with the observation by other authors that the mesophase-to-isotropic liquid transition is reduced by a terminal double bond in the chain. 183,184 The layer spacing of the smectic A phase depends on the type of counterion.…”

“…The compounds with a 1,3-dithiane ring have higher transition temperatures than the corresponding compounds with a 1,3-dioxane ring. It was found that compounds with a terminal double bond in the alkyl chain have a lower clearing point than molecules which do not have this structural feature. , This is in agreement with the observation by other authors that the mesophase-to-isotropic liquid transition is reduced by a terminal double bond in the chain. , The layer spacing of the smectic A phase depends on the type of counterion . For a series of compounds with halide counterions, the layer spacing decreases with increasing size of the halide ion (the largest spacing is found for chloride salts, the smallest spacing for iodide salts).…”

“…Haramoto and co-workers prepared mesomorphic N -alkylpyridinium salts that are substituted in the 4-position by either a 1,3-dioxane ring ( 78 ), − a 1,3-dithiane ring ( 79 ), or a 1,3-oxathiane ring ( 80 ). , The most remarkable property of these ionic liquid crystals is the wide temperature range over which the smectic A phase is stable. Many of the compounds are also liquid−crystalline at temperatures far below room temperature.…”