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

• Published in: Molecular Crystals and Liquid Crystals Vol. 732; no. 1; pp. 64 - 75
• Main Authors: Fouad, Farid S., Khairuddean, Melati, Twieg, Robert J.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 01-06-2022; Taylor & Francis Ltd
• Subjects: 1,3,4-Oxadiazoles; Chains; Crystal structure; Crystallinity; fluorinated liquid crystals; Fluorination; lateral ring fluorination; Liquid crystals; Oxadiazoles; smectic liquid crystals; Synthesis; Thiadiazoles
• ISSN: 1542-1406; 1563-5287; 1527-1943
• DOI: 10.1080/15421406.2021.1980711

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.