Liquid Crystalline 2-[4-(2-chloroalkanoyloxy)-phenyl -5-(4-n-hexyloxyphenyl)-pyrimidines–New Ferroelectric Compounds Exhibiting Interesting Polymorphism

Abstract

Seven chiral 2-[4-(2-chloroalkanoyloxy)-phenyl -5-(4-n-hexyloxyphenyl)-pyrimidines were synthesized and their liquid crystalline as well as their ferroelectric properties investigated. The new compounds possess a rich variety of polymorphism including six different smectic phase types. On the basis of X-ray investigations and miscibility studies these smectic modifications were classified as SmA, SmC*, SmJ*, SmG*, SmH* and SmM'* whereby SmM'* denotes a smectic phase which presumably is identical to the recently discovered SmM* phase. In the second part of this paper the ferroelectric properties of the 2-[4-(2-chloroalkanoyloxy)-phenyl -5-(4-n-hexyloxyphenyl)-pyrimidines were investigated. High values of spontaneous polarization (up to about 400 nC/cm²) were established for the SmC* and SmM'* phases of these compounds as well as in one case also for the SmJ* phase.

Key Words:

• 2,5-diphenylpyrimidines
• ferroelectric liquid crystals
• X-ray
• miscibility studies
• SmM phase