Effect of Pyridine on the Mesophase of Teraryl Liquid Crystals: A New Series of Nematic Liquid Crystals Named 2-(4-Alkoxybiphen-4'-yl)-5-methylpyridines.

A new series of teraryl 2-(4-alkoxybiphen-4'-yl)-5-methylpyridines (nO-PPPyMe, n = 3-8) nematic liquid crystal compounds, bearing a biphenylene core and a picoline terminus, were synthesized using a short two-step reaction, and overall yields between 34% and 38% were obtained. Spectral analysis results were in accordance with the expected structures. The thermotropic behavior of the teraryl liquid crystal compounds was investigated through polarized optical microscopy and differential scanning calorimetry. All compounds exhibited a solely enantiotropic nematic phase at the medium-high temperature range of 162.4-234.2 °C. Furthermore, the results for the nO-PPPyMe series were analyzed relative to three other compound series, mO-PPPyCN (m = 2-8), iO-PPQMe (i = 3-8) and xO-PPyPMe (x = 1-10). Consequently, the effect of pyridine on the mesophase of teraryl liquid crystals was demonstrated.

A new series of kinked liquid crystals: 2-(6-alkoxynaphthalen-2-yl)-6-methoxyquinolines.

A new series of 2-(6-alkoxynaphthalen-2-yl)-6-methoxyquinolines (nO-NpQOMe, n = 3-8) liquid crystal compounds, a linear molecular structure with two kinks, were synthesized using a short two-step reaction with overall yields between 43% and 58%. Spectral analyses were in accord with the expected structures. Thermotropic behavior of these liquid crystal compounds were investigated using polarized optical microscopy and differential scanning calorimetry. All compounds exhibited purely enantiotropic nematic phase at the medium-high temperature range of 162.4-234.2 °C. However, short ranges of nematic phase, 20.5-16.6 °C at heating and 46.7-37.0 °C at cooling, were observed in these linear liquid-crystalline compounds with two kinks.

Synthesis and thermotropic studies of two novel series of kinked liquid crystals: 2-(4'-alkoxybiphen-4-yl)-6-methylquinolines and 2-(6-alkoxynaphthalen-2-yl)-6-methylquinolines.

Two novel homologous series of kinked (Z-shaped) liquid crystalline compounds were synthesized using a short two-step reaction. Yields of 30%-40% and 51%-57% were obtained for 2-(4'-alkoxybiphen-4-yl)-6-methylquinolines (nO-PPQMe, n = 3-8) and 2-(6-alkoxynaphthalen-2-yl)-6-methylquinolines (iO-NpQMe, i = 3-7), respectively. Spectral analyses agreed with the expected structures. The thermotropic behaviors of these compounds were investigated using polarized optical microscopy and differential scanning calorimetry. An enantiotropic nematic phase appeared to be the main mesophase in these two series of kinked liquid crystalline compounds, and an additional enantiotropic smectic C phase appeared when n = 8.

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.