With our accumulated understanding on CF2CF2-containing organic molecules, we recently achieved synthesis of π-conjugated tricarbocycles with a CF2CF2-containing cyclohexa-1,3-diene skeleton, which was prepared in eight steps from commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene....

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Organic molecules with fluoroalkylene scaffolds, especially a tetrafluoroethylene (CF2CF2) moiety, in their molecular structures exhibit unique biological activities, or can be applied to functional materials such as liquid crystals and light‐emitting materials. Although several methods for the syntheses of CF2CF2‐containing organic molecules have been reported to date, they have been limited to methods using explosives and fluorinating agents. Therefore, there is an urgent need to develop simple and efficient approaches to synthesize CF2CF2‐containing organic molecules from readily available fluorinated substrates using carbon‐carbon bond formation reactions. This personal account summarizes the simple and efficient transformation of functional groups at both ends of 4‐bromo‐3,3,4,4‐tetrafluorobut‐1‐ene and discusses its synthetic applications to biologically active fluorinated sugars and functional materials, such as liquid crystals and light‐emitting molecules.

Tetrafluorocyclohexa-1,3-diene ring-containing tricyclic π-conjugated molecules are promising negative-dielectric-anisotropy guest species for vertical-alignment-type liquid-crystalline (LC) displays. Building on our previous work reporting the excellent photoluminescence (PL) properties of tricyclic π-conjugated molecules with central tetrafluorocyclohexa-1,3-diene rings, we herein synthesized four analogous molecules with terminal tetrafluorocyclohexa-1,3-diene rings from commercially available precursors and investigated the effects of substituent type and diene ring position on PL and LC properties using microscopic and spectroscopic methods. One of the prepared molecules exhibited a relatively planar molecular structure and formed herringbone-type aggregates via π/F and CH/π interactions instead of forming stacked aggregates via π/π stacking interactions, thus exhibiting relatively strong PL in solution and crystalline states. Moreover, the PL color of this compound depended on the electronic character of its terminal substituents along the long molecular axis. Of the four prepared species, two featured terminal ethyl groups and formed one or more LC phases. The PL properties of these phases indicated that the related phase transition induced changes in the aggregate structure, PL wavelength, and PL color. Our results expand the applicability of CF2CF2 moiety-containing tricyclic compounds as functional molecules for the fabrication of next-generation PL, LC, and PL-LC materials.