Synthesis and characterisation of novel rod-disc oligomers

Abstract

Microwave-promoted synthesis of novel rufigallol-based liquid crystalline oligomers, containing six rod-like cyanobiphenyl moieties connected to the rufigallol core via flexible alkyl spacers, is reported. The synthesis of the target compounds was challenging since classical reactions failed to produce these oligomers. Differential scanning calorimetry and polarising optical microscopy analysis revealed the existence of a nematic phase with a shorter spacer and a smectic A (SmA) phase with a longer spacer. The compound with medium alkyl spacer exhibits both nematic and SmA phases at higher temperature and a re-entrant nematic phase at lower temperature.