Synthesis, Physical Properties and Structural Relationships of New, End-Chain Substituted Nematic Liquid Crystals

Abstract

New nematic liquid crystalline phenylcyclohexanes with (i) a terminal side-chain vinylic group some distance from the rigid core and (ii) both polar and non-polar terminal side-chain groups, were synthesized.

Investigations of their elastic, birefringence, dielectric and rotational viscous properties have shown several new odd-even effects. These are attributed to side-chain Simultaneous odd-even effects were found for δ, δn, k ₃₃/k₁₁ and K = k ₁₁ + (k ₃₃ - 2k ₂₂)/4. Furthermore, unusually low twist elastic constants, k ₂₂ were obtained for polar 6-alkenyls as well as for compounds exhibiting groups with permanent dipole moments in even side-chain positions.

Key Words:

• nematic mesogens
• odd/even effets
• vinyl groups