Piperidine and 3,3,4,4,5,5-hexafluoropiperidine as terminal groups: Syntheses and properties as new liquid crystals

摘要

A series of novel ester liquid crystals with piperidine or 3,3,4,4,5,5-hexafluoropiperidine as terminal group have been prepared in good yield. Some of the new compounds show broad mesomorphic phase range and good thermal stability. Their structures were modified by varying the terminal N-heterocycles, lateral fluorine substituent on the benzene ring, and the number of the cyclohexane ring in the molecules. The compounds 3/2-0F, 5/2-0F and 3/2-1F exhibited nematic phase (N), and 5/2-1F displayed smectic B phase. Compared with compound 3/2-1F (N), 5/2-1F has a longer n-pentyl substituent on the cyclohexane ring. Variation of the terminal N-heterocycles from piperidine to 3,3,4,4,5,5-hexafluoropiperidine causes the absence of mesomorphism behaviors.

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