Mesomorphic Heterocyclic Homologous Series: 1.7-(4'-n-Alkoxybenzoyloxy)-3-acetylcoumarins 11. 4'-Formylphenyl 7-n- alkoxycoumarin-3-carboxylates

Two homologous series of coumarin derivatives have been synthesized and mesomorphic behavior of their members has been studied. In case of Series I, mesomorphism does not begin to appear until the butyl homolog, which is monotropic nematic. The remaining members of the series exhibit both nematic and smectic or only smectic properties. In case of Series II, all the homologs, except the first seven, exhibit only a smectic phase. In both the series, plots of S-N or I transition temperatures versus the number of carbon atoms in the alkoxy chain show an ascending tendency.