A new homologous series of benzothiazole liquid crystals comprising a terminal ethoxyl substituent and imine linkage was studied. All members can be differed from the number of carbons at the alkoxy chain (CnH2n+1O-, where n = 2-10, 12, 14, 16, 18). Mesomorphic behaviours of the present compounds was characterised and studied by differential scanning calorimetry and polarizing optical microscopy. All the present molecules with 2-(benzylidenamino)benzothiazole as core system exhibited mesomorphism. Early members (n = 2-7) are pure nematogenic liquid crystals. Medium members (n = 8-10, 12, 14, 16) are polymorphic liquid crystals wherein these compounds exhibited nematic and smectic phases. However, the properties of the medium members still differ in terms of transition temperatures, phase stability (monotropic or enantiotropic) and types of smectic phase (smectic A or C). The last member with the longest alkoxy chain is pure smectogenic A liquid crystal. In addition, X-ray diffraction technique was used and it confirmed monolayer arrangement of SmA phase in n-tetradecanoyloxy derivative.
- Schiff bases
- X-ray diffraction analysis