The liquid-crystalline properties of the homologous members of alkyl 4-(2-p
erfluorooctyl)ethoxy-3-R-benzoates (R = H (1), NO2 (3), Br (4)) show a new
mesomorphic behavior. The lower alkyl (methyl-pentyl) esters of 1 exhibit a
smectic A phase, and the smectic A-isotropic transition temperature tends
to decrease with increasing the carbon number of the alkyl group, where the
layer spacing of the smectic A phase tends to become short with increasing
carbon chain length. The hexyl-decyl esters are non-mesogenic, and the aft
er members again show a smectic A phase. The similar trend has been found f
or 3 and 4. Homologous members of alkyl 4-(2-perfluorodecyl)ethoxybenzoates
(2) also show a similar thermal behavior. The smectic properties are stron
gly dependent on the relative constitution of the perfluoroalkyl group to t
he alkyl one within the molecule. The molecular arrangement of the smectic
A phase is discussed.