Liquid crystals with multiple fluorinated bridges in the mesogenic core structure

Controllable double CF2-insertion into sp2 C–Cu bond using TMSCF3: a facile access to tetrafluoroethylene-bridged structures

“…[1][2][3][4] Among various uorinated functionalities, the tetrauoroethylene motif (-CF 2 CF 2 -) has attracted considerable attention because of its applications in agrochemicals 5 and liquid-crystalline materials. [6][7][8] Moreover, the introduction of -CF 2 CF 2group into liquid crystals oen results in highly advantageous properties such as high clearing temperature, broad nematic phase range, low rotational viscosity and high dielectric anisotropy. [6][7][8] Therefore, it is of strong demand to access tetrauoroethylene-bridged molecules.…”

Advances in the Synthesis and Application of Tetrafluoroethylene‐ and 1,1,2,2‐Tetrafluoroethyl‐Containing Compounds

“…Ten years later, they reported a detailed account on the synthesis and properties of those compounds ( 151 , Scheme ), showing that they can exhibit increased clearing temperatures (i.e., temperatures under which the compounds exist in the liquid crystalline state) by 50–70 K compared to direct analogs lacking the CF 2 CF 2 linker . At the same time, improved structure 152 (Scheme ), containing one tetrafluoroethylene and one difluorooxymethylene bridge, was found to possess even more favorable properties for the liquid crystal applications . The authors later suggested through a computational study that the beneficial effect of the fluorinated bridges stems from enhanced rigidity of the core moiety due to steric and stereoelectronic effects .…”

“…[27] At the same time, improved structure 152 (Scheme 91), containing one tetrafluoroethylene and one difluorooxymethylene bridge, was found to possess even more favorable properties for the liquid crystal applications. [234] The authors later suggested through a computational study that the beneficial effect of the fluorinated bridges stems from enhanced rigidity of the core moiety due to steric and stereoelectronic effects. [235] Other related derivatives were described in a patent.…”

Halofluorocarbons, Hydrofluorocarbons, and Related Compounds

“…If both bridge elements CF 2 CF 2 and CF 2 O are introduced at the same time in their most effective positions within the mesogenic core structure (65), the difluorooxymethylene group compensates some of the negative side effects of the tetrafluoroethylene bridge, for example, the relatively high melting point of 58 [76]. The success of this concept indicates that different structural features within a liquid crystalline structure can be used relatively independently to influence and optimize the physical characteristics of the material (Table 8.15).…”