Homologous series of 4-cyanophenyl 4-(3-alkoxybenzoyloxy)benzoates, 4-(4-cyanobenzoyloxy)phenyl 3-alkoxybenzoates, and 4-(4-nitrobenzoyloxy)phenyl 3-alkoxybenzoates have been prepared. The nematic-isotropic transition temperature decreases on ascending the series. However, the smectic A phase is formed even in the higher members, while the alkoxy group at 3 position would increase the bend of the molecular structure. On the other hand, the related compounds having a long alkoxy group instead of the cyano or the nitro group are non-mesogenic. The formation of the liquid crystalline phases for the polar compounds is discussed in terms of the formation of the antiparallel dimers.