Supramolecular Metallomesogens: Hydrogen-Bonded Ferrocene-Containing Liquid Crystals Which Display Bicontinuous Cubic Phases
Two series of hydrogen-bonded liquid-crystalline ferrocenes have been prepared by reacting ferrocene derivatives carrying a carboxylic acid function and two flexible alkyl chains (containing n = 8, 10, or 12 carbon atoms) with stilbazoles bearing a flexible alkyl chain (containing m = 6 or 10 carbon atoms). The first family of materials (m = 6; n = 8, 10, 12) gave rise to smectic A/C and/or cubic (Ia3̄d space group) phases, and the second series of complexes (m = 10; n = 8, 10, 12) displayed cubic phases (Ia3̄d space group). A subtle balance between the volume occupied by the central core and the flexible chains, as well as the surface between both parts, are responsible for the formation of the mesophases. Hydrogen bonding is an elegant alternative to covalent bonding for the design of ferrocene-containing liquid crystals.