Intercalated liquid-crystalline phases formed by symmetric dimers with an α,ω-diiminoalkylene spacer

摘要: Four series of symmetric, dimeric molecules with flexible α,ω-diiminoalkylene spacers have been synthesised and characterised by polarising optical microscopy, differential scanning calorimetry, X-ray diffraction. The effects on the mesomorphism various alkylene spacer (number methylene units m = 5 to 8) as well terminal alkoxy chain length (n 4 14) mesomorphic properties studied. compounds an even-numbered display, in addition a nematic phase, smectic phases whose nature depends ratio between (n/m). A modulated SmA phase was found for n/m 1 1.6 SmC/crystal G polymorphism emerges at > 1.7. In contrast, all liquid-crystalline dimers odd-numbered display intercalated B6 regardless length. preference structures is discussed based dipolar considerations following electronic structure calculations using model molecule.