Nematic ionic liquid crystals based on pyridinium salts derived from 4-hydroxypyridine

Abstract

A series of pyridinium salts with various counterions (Br⁻, NO₃⁻, BF₄⁻, PF₆⁻, OTf⁻ and SCN⁻) and different spacer chain lengths, which display a nematic phase, have been designed and prepared. They are derived from 4-hydroxypyridine and possess two mesogenic cyanobiphenyl groups attached to the pyridinium unit via a flexible long alkyl spacer (6, 9, 10). These salts exhibit solely a nematic phase with the thermal range influenced by the counterion employed and spacer length.