Diphenyl-1,3,4-oxadiazoles: synthesis and influence of side chain semifluorination and lateral ring fluorination on liquid crystalline properties

We present the synthesis and liquid crystalline properties of four sets of diphenyl-1,3,4-oxadiazole based compounds (Sets 1-4). The influence of side chain and lateral fluorinations is discussed. In this study, side chain fluorination (Sets 2 and 3) induces liquid crystalline properties, while lateral fluorination (Set 4) has not induced mesogenic properties. Compounds with either one or two semifluorinated side chains are smectic mesogens (SmC and/or SmA). A comparison among the diphenyl-1,3,4-oxadiazole, biphenylyl-1,3,4-oxadiazole, diphenyl-1,3,4-thiadiazole, and the biphenylyl-1,2,4-oxadiazole cores, which we have previously reported, is discussed.