Synthesis and mesomorphic properties of 1,1-difluoroalkyl-substituted biphenylthienyl and terphenyl liquid crystals. A comparative study of mesomorphic behavior relative to alkyl, alkoxy and alkanoyl analogs

A variety of biphenylthienyl and terphenyl-based liquid crystalline materials were prepared that incorporate a 1,1-difluoropentyl terminal group. The mesogenic properties of these compounds were compared and contrasted with analogs where the CF2 moiety was replaced by a -CH2-, -O- or -CO- group. The 1,1-difluoroalkyl group is unique in its behavior and tends to promote orthogonal smectic phase behavior.