Mesomorphic Characteristics of Thermotropic Mesogens p-p'-Disubstituted Phenyl Cinnamates 1: p-(p’ -n- Alkoxycinnamoyloxy)-Acetophenones

Abstract

p-n-alkoxycinnamoyl cholrides when treated with p- hydroxyacetophenone yield a homologous series ofmesogens. The first member is a monotropic nematogen; exhibition of enantiotropic nematic mesophase begins from the second memeber and persists up to the butyl derivative. Both smectic and nematic mesophases are exhibited by the pentyl and hexyl derivatives. The homologues rom heptyl to octadecyl exhibit smectic phase only. the usual odd-even effect is well displyed. Nematic-isotropic treansition curves for both even and odd memebers showf an initial slight slump up to the heptyl derivative; the smectic-isotropic transition curve shows a rising tendency followed by a slight downward slope towards the highest member. The homologous series is thermally very stablef and exhibits a wide mesomorphic range. The thermal stabilities and other characteristics are discussed.