ODD-EVEN EFFECTS IN THE THERMOTROPIC AND OPTICAL-PROPERTIES OF CHIRALTRIPLET LIQUID-CRYSTALS

A series of chiral triplet liquid crystalline compounds with a central biphenyl group to which two dihydrocholesteryl groups are attached vi a two flexible alkanoate spacers has been prepared and investigated. A s a function of spacer length, these compounds show strong odd-even ef fects for the phase transition temperatures, the corresponding entropy changes and the selective reflection wavelengths associated with the chiral nematic phases. Asymmetrical compounds with one odd and one eve n number of methylene groups in their spacers have properties intermed iate between those of symmetrical compounds with two odd or two even s pacers.