Senven enantiotropically nematic fumaric ester derivatives, 1-[[(E)-3-alkoxycarbonyl)acryloyl]oxy]-4-(4-methoxyphenylazo)benzene (1), were prepared. The 1 compounds which have unbranched ester alkyl groups showed decreased phase-transition temperatures and narrowed nematic states with the increase in the length of the alkylchain, while the 1 compounds with terminal branched alkyl groups decrease drastically