Synthesis and thermotropic studies of a new series of teraryl liquid crystals 2-(4'-alkoxybiphen-4-yl)-5-cyanopyridines.

A new series of teraryl 2-(4'-alkoxybiphen-4-yl)-5-cyanopyridines (nO-PPPyCN, n = 2-8) compounds, bearing a cyanopyridine terminus, were synthesized using a short 2-step reaction with overall yields between 33% and 69%. Spectral analyses were in accord with the expected structures. Thermotropic behavior of the teraryl compounds was investigated using polarised optical microscopy and differential scanning calorimetry. All compounds exhibited both enantiotropic nematic and smectic A phases, with an additional enantiotropic smectic C phase when n = 7 and 8. Polymesomorphism appears to be a common behavior in this series of linear liquid crystal compounds.