TRANSIMINATION - AN EFFICACIOUS REACTION FOR THE SYNTHESIS OF MACROCYCLES

A new family of main-chain liquid crystal polymers containing azomethi ne units have been synthesized and characterized. Our attention has be en focused on their strong tendency to generate macrocyclic dimers (AB )(2) constituted with two mesogenic rods and siloxane spacers. In favo urable conditions (diluted solution, acid catalysis) macrocycles may b e rapidly formed and purely obtained by fractionation. Synthetic aspec ts and main thermotropic properties are discussed. In spite of their l arge size some macrocycles have been obtained as single crystals and t hen characterized by X-ray diffraction.