Synthesis and Structural Studies of Polyphilic Mesogens with Central or Terminal Perfluoroalkyl Chains

Benzyl 4-iodoperfluorobutanoate was synthesized by partial pyrolysis of perfluoroglutaryl chloride in the presence of potassium iodide followed by esterification. This compound gives access to mesogenic molecules with alkyl chain, perfluoroalkyl central bridge, and biphenyl moieties. Segregation of these chemical fragments depends on the molecular design. The molecule with a central alkyl chain forms smectic A layers (123−145 °C) with interdigitation of aliphatic and aromatic parts. In contrast, the smectic E phase is observed between 60 and 87 °C when the perfluoroalkyl chain is in the center of the molecule. In this case, X-ray diffraction data are consistent with the presence of three sublayers differing in their chemical nature.