Series of novel star-shaped liquid crystals containing [1,1ʹ-biphenyl]-4,4ʹ-diyl diisonicotinate mesogens with various counterions (Br − , B-SO 3 − ,C-SO 3 − ,H 2 PO 4 − , BF 4 − ) have been synthesized and characterized, which display a nematic phase. The molecular structures of the liquid crystals, thereof consisting of rod-like mesogens linked together by different long alkyl spacers to a small disc-like core of central benzene-1,3,5-triyl triisonicotinate, have been fully characterized by 1 H NMR. Their thermal and supramolecular organization behaviours have been studied by combining polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering. These investigations showed that the mesophase temperature range increased with increasing alkyl chain length and the clearing point decreased with increase of anion size. These star-shaped liquid crystals have a long and ordered molecular structure, the electron delocalization of the π-π stacking conjugation effect and the electrostatic attraction of ionic make them have good ferroelectric properties and ionic conductivity properties. The interest in preparing ionic liquid crystal with a nematic phase lies in the technological applications as it is well known that the nematic phase has the highest fluidity of all liquid crystalline phases and hence the possibility to align it by applying an external electric/magnetic field, commonly used in electro-optical devices.
A series of quaternary phosphonium ions-containing main-chain ionic liquid-crystalline polymers with tri-tolylphosphines as cationic groups have been synthesized and characterized. The molecular structures of all compounds have been determined. Test results show that the liquid crystal properties of the polymer, the quaternary phosphonium ions-containing main-chain ionic liquid-crystalline polymers, have lower glass transition temperature and wider liquid-crystalline range, and the BF 4 − and PF 6 − even can make the glass transition temperature drop to more than 10°. The polymers exhibit liquid crystal properties only during temperature rising, the quaternary phosphonium ions-containing main-chain ionic liquid-crystalline polymers show smectic A phase, and the main-chain liquid-crystalline polymers show chiral nematic mesophases. The ionic liquid-crystalline polymers with phosphorus cations show good bactericidal performance, but the anion has no effect on bactericidal properties.
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