Synthesis and characterisation of thieno[3,2-b]thiophene-based linear shaped liquid crystals

A series of thieno[3,2-b]thiophene-based liquid crystalline molecules has been synthesised. To investigate the effects of alkyl substituent groups and structure of mesogenic cores, eight kinds of thieno[3,2-b]thiophene-based molecules containing different alkyl substituent groups and mesogenic cores have been synthesised. These molecules were characterised by differential scanning calorimetry, polarising optical microscopy, ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry and polarised fluorescence spectroscopy. The results indicated that the thieno[3,2-b]thiophene-based donor-acceptor-donor (D-A-D) type molecules showed the presence of a smectic A phase. Changes in the length of alkyl substituents and mesogenic cores affected the phase transitions, optical and electrochemical properties of the molecules.