Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• engineering; thiadiazoles; V-shaped mesogens; Introduction Most molecules forming nematic liquid crystals, the nematogens, are based on rod-shaped (calamitic), anisometric cores with peripheral flexible chains along the molecular long axis [1]. Nematic phases are the simplest liquid crystalline mesophases

• high (above 90 °C). In order to lower the latter, non-symmetric V-shaped mesogens 2 with two arms consisting of different peripheral building blocks have been prepared. The series of molecules 2a–c, 2f with a pentanoic acid ethyl ester group on one side shows a decrease in melting and clearing

• aligned area of 2c on glass at 163 °C. e) Conoscopic picture at 161 °C and f) Conoscopic picture using the circular polariser. X-ray study of nematic mesophases from V-shaped mesogens. A: Diffraction pattern of 2c at 70 °C. B: Model of the local molecular order and characteristic distances corresponding