Synthesis and liquid crystalline properties of several compounds with semi-fluorocarbon chains

Several molecules having long semi-fluoroalkyl chains have been synthesized, and their phase transition temperatures measured by texture observation in a polarizing microscope and DSC. The SmC phase is particularly favoured in this series, especially for compounds with a long semi-fluoroalkyl chain. It was found that when the terminal hydrogen atom of the semifluoroalkyl chain of one of the compounds (D) was substituted by a chlorine atom, the liquid crystalline sequence and ranges did not change; however, the clearing and melting points and T_I-SmA and T_SmA-SmC increased by nearly 10°C.