Novel redox-active ionic thermotropic liquid crystalline complexes of polyelectrolyte and ferrocenyl surfactants

Redox-active polyelectrolyte–surfactant complexes (PSC) were prepared via the ionic self-assembly of sodium poly(styrenesulfonate) (PSS) and ferrocenyl surfactant, (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) in aqueous solution. The PSS–FTMA complex exhibited an ordered interdigitated monolayer mesomorphous structure with the long period of d = 3.13 nm, and was in the ionic thermotropic liquid crystal SmA state at room temperature. Interestingly, in the solid complex, the ferrocenyl moieties formed H-aggregation showing an increase in the π–π* energy transfer of cyclopentadienes in the ferrocene moieties as known from the blue-shift in the UV spectrum. The complexes showed higher thermal stability compared with their components due to the ionic interaction. The PSS–FTMA film had a good redox reversibility, which promised to be used in electrochemical sensors.