THE FORGOTTEN LIQUID-CRYSTALS OF VORLANDER,DANIEL - A NEW LOOK AT MESOGENIC 4-PYRIDONES

Three classes of 4-pyridone (1H-pyridin-4-one) terminated liquid cryst als were synthesized and their mesogenic properties examined. These li quid crystal classes differ in the composition of the aromatic core gr oup which vary among azobenzene, stilbene or tolane groups. The synthe sis of the 4-pyridones was accomplished by aromatic nucleophilic subst itution reaction of the appropriate activated aryl fluoride with 4-hyd roxypyridine, These pyridone liquid crystals possess broad enantiotrop ic nematic and smectic A phases and may possess useful properties such as high birefringence and polarity including hydrogen bonding capabil ity. The original report of a 4-pyridone containing liquid crystal due to Vorlander has been substantiated.